Initial commit of ebook 78112 filesHEADmain

6 files changed, 5017 insertions, 0 deletions

diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..6833f05
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,3 @@
+* text=auto
+*.txt text
+*.md text
diff --git a/78112-0.txt b/78112-0.txt
new file mode 100644
index 0000000..1a5eac9
--- /dev/null
+++ b/78112-0.txt
@@ -0,0 +1,1844 @@
+*** START OF THE PROJECT GUTENBERG EBOOK 78112 ***
+
+
+
+
+  LITTLE BLUE BOOK NO. 895
+  Edited by E. Haldeman-Julius
+
+  Astronomy for
+  Beginners
+
+  Hereward Carrington, Ph.D.
+
+  Author of the following Little Blue Books: No.
+  679, “Chemistry for Beginners;” No. 491, “Psychology
+  for Beginners;” No. 419, “Life: Its
+  Origin and Nature;” No. 524, “Death and
+  Its Problems;” No. 493, “New Discoveries
+  in Science;” No. 409, “Great
+  Men of Science;” etc., etc....
+
+  HALDEMAN-JULIUS COMPANY
+  GIRARD, KANSAS
+
+
+
+
+  Copyright, 1925,
+  Haldeman-Julius Company
+
+
+  PRINTED IN THE UNITED STATES OF AMERICA
+
+
+
+
+CONTENTS.
+
+
+                                                     Page
+
+  Introductory                                          5
+
+  Astrology                                             7
+
+  The Solar System                                      8
+
+  The Sun                                               9
+
+  Mercury                                              11
+
+  Venus                                                12
+
+  The Earth                                            13
+
+  Mars                                                 13
+
+  Jupiter                                              16
+
+  Saturn                                               17
+
+  Uranus                                               18
+
+  Neptune                                              18
+
+  The Minor Planets                                    19
+
+  Are There Other Planets?                             20
+
+  The Moon                                             20
+
+  The Origin of the Solar System                       24
+
+  Constellations                                       27
+
+  Meteors: “Shooting Stars”                            28
+
+  Meteorites                                           29
+
+  Comets                                               30
+
+  Nebulae                                              32
+
+  The Milky Way                                        33
+
+  The Number of Stars                                  33
+
+  The Position of Our Solar System                     35
+
+  The Movement of Our Solar System                     36
+
+  Distances of the Stars                               36
+
+  Temperature of the Stars                             37
+
+  Fixed Stars                                          37
+
+  Double Stars                                         38
+
+  Colored Stars                                        38
+
+  Variable Stars                                       39
+
+  Temporary Stars                                      40
+
+  Star Groups--Clusters                                40
+
+  Eclipses                                             41
+
+  Telescopes                                           43
+
+  The Spectroscope: Spectrum Analysis                  43
+
+  Photography                                          46
+
+  The Tides                                            47
+
+  Gravitation                                          48
+
+  The Ether                                            49
+
+  Atomic Analogies                                     49
+
+  Thunder and Lightning                                50
+
+  Fireballs                                            50
+
+  Atmospheric Electricity                              50
+
+  The Earth’s Magnetism                                51
+
+  The Aurora Borealis                                  51
+
+  Time: Measurement of                                 52
+
+  Space: Measurement of                                52
+
+  The International Day Line                           54
+
+  Calendars, etc.                                      54
+
+  Curved Space                                         55
+
+  The Temperature of Space                             55
+
+  Light in Space                                       55
+
+  Life in Space                                        56
+
+  The Causes of an Ice Age                             56
+
+  Why Do Stars “Twinkle”?                              56
+
+  Why Does the Moon Sometimes Appear Larger?           57
+
+  Are the Planets Inhabited?                           57
+
+  A Few Definitions                                    58
+
+
+
+
+INTRODUCTORY
+
+
+Astronomy is one of the oldest of the sciences--as it is one of the
+most fascinating! The early Egyptians, Assyrians, Babylonians and
+Chaldeans were, as we know, great astronomers, and, considering that
+they were compelled to make their observations without the aid of
+telescopes, some of their conclusions are truly remarkable in their
+accuracy. Men must always have gazed at the stars, and wondered at
+their number and their beauty; yet it is only within the past three or
+four centuries that accurate ideas as to the nature, size and structure
+of our Universe have come into being. No subject is so calculated to
+impress upon man his own relative insignificance as astronomy--to show
+him that the speck of matter upon which he dwells is so small that it
+cannot even be seen, from a relatively short distance in space! How
+puny and absurdly trifling seem his bickerings and his disputes, his
+wars and his hates, his jealousies and his failures, when viewed from
+the standpoint of infinite time and infinite space; mere struggles
+upon an ant hill, which, a few million years from now, will be
+uninhabitable, while the sublime immensity of Nature will proceed as if
+nothing had happened!
+
+Yes, astronomy is a fascinating and romantic study, and the following
+little book is an attempt to summarize, very briefly, the most
+important findings of modern astronomical science upon this question.
+I have endeavored to make the subject as simple as possible, and to
+avoid all terms of a technical character, unless these are fully
+explained. It is my hope that the reader may be enabled to gain a
+fairly clear and accurate idea as to the nature and constitution of our
+Universe by a perusal of this little book.
+
+
+
+
+ASTRONOMY FOR BEGINNERS
+
+
+
+
+ASTROLOGY
+
+
+Those who have not studied this subject will often ask the question:
+“What is the difference between Astronomy and Astrology?” It is merely
+this: Astronomy studies the heavenly bodies, and their movements, etc.,
+by all available scientific means; while astrology, also utilizing
+this material, further asserts that the particular relative positions
+which the sun, moon, planets and other heavenly bodies occupy at the
+moment of birth _influence the individual_ born at that moment, and
+continue to influence him all through life. In other words, astrology
+is undoubtedly an exact science in so far as its astronomical _data_
+are concerned; but its further inference, as applied to the living
+human being, is not; it depends upon historic beliefs and traditions
+which have been handed-down for centuries. So far as astronomers have
+been enabled to ascertain, there is not the slightest scientific basis
+for any belief in astrology; assuredly it is a curious and interesting
+occult study, but it must be understood to lie within that realm,
+rather than in that of exact astronomical science.
+
+
+
+
+THE SOLAR SYSTEM
+
+
+When we speak of the “solar system,” we mean our central Sun, and the
+various planets which revolve around it. The planets, beginning with
+the one nearest the Sun, and proceeding outwards into space, are:
+Mercury, Venus, The Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Most
+of these planets have in turn, circling round them, smaller bodies
+of satellites; the Earth has but one--the Moon. Other planets have
+more than one. The planets vary greatly in size, as well as in their
+relative distances from the Sun. The following may help the reader to
+form a mental picture of their relative distances and sizes:
+
+Imagine a large open common; on it place a globe 2 feet in diameter,
+by way of representing the Sun; Mercury will then be represented by a
+mustard seed at a distance of 82 feet; Venus by a pea at a distance of
+142 feet; the Earth also by a pea, at a distance of 215 feet; Mars will
+be a small pepper corn, at a distance of 327 feet; the Minor Planets
+by grains of sand at distances varying from 500 to 600 feet; then a
+moderate sized orange ¼ of a mile distant from the central point will
+represent Jupiter; a small orange ⅖ths of a mile, Saturn; a full-sized
+cherry, ¾ths of a mile, Uranus; and lastly a plum, at 1¼ miles,
+Neptune,--the most distant planet yet known,--though some astronomers
+suspect there may exist another planet still further off, and hope one
+day to find it. (On the same scale, the _nearest_ “fixed” star would be
+7,500 miles distant).
+
+
+
+
+THE SUN
+
+
+The Sun is the center of our solar (sun) system; it is the great giver
+of light and heat, without which life upon our planet would soon become
+extinct. It is an immense body, more than a million times the size
+of our earth. In fact, its _radius_ is nearly twice the distance of
+the moon from the earth! The mass of the Sun is 332,000 times that of
+the earth. It gives 600,000 times as much light as the full moon. The
+energy radiated per square yard from the Sun is equivalent to 140,000
+horse power. The heat radiated by the sun would melt a layer of ice
+4,000 feet thick every hour, all over its surface. Various estimates
+of the amount of heat upon the surface have been made, but these do
+not agree,--figures all the way from 10,000° F. to 180,000° F. having
+been given. Certain it is that its internal heat is terrific, and there
+is every indication that this heat has been more or less constant for
+millions of years in the past. No purely physical theories of its heat
+are at all satisfactory. The ultimate nature and source of the sun’s
+heat are unknown--though various theories have been advanced by way of
+explanation. I have discussed this question at some length, however in
+my little book in the present series, “New Discoveries in Science,” to
+which the reader is referred. (“What Keeps the Sun Hot?”)
+
+The nature and constitution of the sun have, of course, been studied
+intensively for many years by astronomers. The apparent surface of the
+sun is called the “photosphere” (light surface). It is the part that
+gives forth most of the light and heat. Above the photosphere lies
+a sheet of gas, probably from 500 to 1,000 miles thick, called the
+“reversing layer,” which is cooler than the photosphere. Outside the
+photosphere is another layer of gas, from 5,000 to 10,000 miles deep,
+called the “chromosphere” (cooler sphere). The outermost portion of the
+Sun is the “corona” (crown). It is a halo of pearly light surrounding
+the sun, but it cannot be seen except during a total eclipse. It is of
+irregular form, and gradually fades out into the blackness of space
+at a distance of from 1,000,000 to 3,000,000 miles. This must not be
+confounded with the so-called “prominences,” which are vast eruptions
+of flame, spurting out from the sun’s surface, and extending into space
+for enormous distances--perhaps half a million miles! These also travel
+with enormous velocity--five or six hundred miles per second. The earth
+would appear an insignificant speck of dust, in this vast, roaring
+furnace of flame!
+
+Of late years, the question of the so-called “sun spots” has aroused
+a great deal of interest, partly by reason of the fact that they
+apparently affect electrical and magnetic conditions upon the earth.
+These “spots” seem to reappear at stated intervals, and about every
+eleven years reach their maximum intensity, (The period of the
+revolution of the sun on its own axis has been estimated by their
+study.)
+
+Although the sun-spots were studied before the eighteenth century,
+it is only within the past few years that the significance of these
+enormous spots has become known. For long it was thought that they were
+merely the great volcanoes of the sun; centers of great heat, generated
+by the glowing, fiery gases of the sun. In 1908, however, Prof. Hale
+demonstrated that the sun-spots acted as attraction centers, which drew
+towards them the hydrogen of the solar atmosphere. “Subsequently, it
+was found that these spots are the seats of great cyclones, in which
+cool hydrogen gas is set whirling and is sucked down in the great
+mælstrom of the Sun, rushing into the center of the spot at the rate of
+60 miles a second. Consequently the spots are the center of great solar
+disturbances, which are of an electromagnetic nature.” From this it was
+concluded (1) that the spots are cooler than the surrounding area; (2)
+they are centers of violent cyclones; and (3) they are magnetic fields
+of great intensity. The connection of sun-spots with our weather, and
+the relation of one to the other, have also been studied within the
+past few years.
+
+
+
+
+MERCURY
+
+
+This is the smallest of the planets in our solar system, being only
+about 3,000 miles in diameter. It revolves round the sun in almost
+exactly 88 days, at a distance of approximately 36,000,000 miles,
+varying between 28½ million to 43½ million miles. Owing to its
+smallness, it is often difficult to see this planet, and a powerful
+telescope must be employed to study it effectually. It is thought
+that Mercury possesses mountains, but it is practically devoid of
+atmosphere. Dark, irregular spots have been observed upon the planet,
+and its surface is thought, by some astronomers, to resemble that of
+Mars, to a great extent. The solar heat on Mercury is about seven
+times that on us, owing to its proximity to the Sun. Schiaparelli,
+and others, have contended that the period of rotation of Mercury is
+exactly equal to its period of revolution round the Sun. If that be
+true, one side of the planet is always turned to the Sun, and the other
+side away from it. One side of the planet would thus be intensely hot,
+while the other side would be icy cold. Comparatively little is known
+concerning this small planet, though much study has been devoted to it.
+
+
+
+
+VENUS
+
+
+This is one of the brightest and most beautiful “stars” in the sky,
+and has for long been the theme of poets. It is practically the same
+size as our earth, its diameter being approximately 7,500 miles. It
+travels round the Sun in 224 days, at a mean distance of 67,000,000
+miles. It revolves on its own axis in about 23½ hours, so that its days
+are nearly the same as ours. It is thought that Venus has a fairly
+dense atmosphere, and also water-vapor, which proves the existence
+of water upon its surface. Dense layers of cloud exist in the upper
+regions of its atmosphere, making direct observations of its surface
+very difficult. For this reason, comparatively little is known as to
+the conditions on the surface of Venus. Every eighth year Venus passes
+through a period of great brilliance, being then so bright as to cast
+a shadow, like the Moon. Venus must have a higher temperature than
+our earth; its sky is always overcast; thunder and lightning must be
+never-ending. Some controversy has existed as to the habitability of
+Venus; but the consensus of opinion is that life would be practically
+impossible upon its surface.
+
+
+
+
+THE EARTH
+
+
+The earth on which we dwell was thought by the ancients to be the
+center of the entire Universe--the Sun, stars and the vast host of
+Heaven were thought to revolve around it. This was the so-called
+“geocentric” theory. It was later on displaced by the so-called
+“heliocentric” theory, when it was found that the Sun, and not the
+Earth, was the center of our system. It only remains to be said
+that our Earth is the third of the planets which revolve round the
+Sun--Mercury and Venus being nearer the Sun than we are, and the others
+still further removed in space. We are thus but one of a number of
+similar bodies moving through space, all revolving round the central
+Sun.
+
+
+
+
+MARS
+
+
+This now-famous planet is somewhat smaller than our earth, being about
+5,000 miles in diameter. It travels round the Sun in 686 days, at a
+mean distance of 140,000,000 miles. The eccentricity of its orbit is
+considerable. Mars appears to us reddish in color, owing to the vast
+stretches of arid soil (desert) which exist upon its surface. Water
+exists, but it is relatively scarce; it is gradually drying-up, as it
+does in the case of all bodies of the kind--the water on our own earth
+is very gradually becoming less and less, as the centuries pass.
+
+Mars has been drawn particularly to the public’s attention, of late
+years, by reason of the dispute (still raging) as to its habitability,
+and the character of its so-called “canals”--the more or less regular
+markings, like long, dark lines which have been seen to exist upon its
+surface. Its surface has accordingly been studied minutely for many
+years, but it may be said that no unanimity of opinion exists as to its
+being an inhabited planet. Says Kæmpffert, in his “Astronomy,” (pp.
+183-84):
+
+“The mapping of Mars is no recent matter, for even in 1659 a rough
+sketch of the surface of the planet was made by Huygens, in which
+the V-shaped markings at the equator, pointing to the north, can be
+identified as the _Syrtis Major_. This was followed by rough sketches
+from time to time down to 1840, when Maedler first began a systematic
+charting of the planet. His map was followed in 1864 by Kaiser’s, by
+Flammarion’s in 1876, and Greene’s in 1877. Drawings of various parts
+of the planet were made during these intervals, but were not combined
+into good charts.”
+
+“Observations made by Prof. Lowell and his staff at the Observatory,
+at Flagstaff, Arizona, have had a study of this planet especially in
+view.... The surface of Mars as seen in the telescope, is composed of
+two white polar caps, which wane with the approach of summer; orange
+areas, which are supposed by Lowell to be deserts, and blue-green
+areas, which change their hue to orange during the Martian autumn and
+winter, and resume their verdant tint in spring. The planet is covered
+with a network of fine lines, first discovered by Schiaparelli, in
+1877; and called by him ‘canals’--a designation by which they are still
+known. These canals connect the polar caps with the temperate and
+equatorial zones. According to Prof. Lowell, they may be regarded as
+planetary irrigation ditches, which serve the purpose of leading the
+melting water of the poles to those desert regions which would still
+blossom, if properly watered. The canals disappear with the approach of
+winter, and creep down from the poles towards the equator in summer--a
+phenomenon which long puzzled astronomers, until Pickering ingeniously
+suggested that we see, not the canals themselves (for they are much too
+narrow) but the vegetation which fringes their banks--which withers as
+the cold of winter descends, and which flourishes with the melting of
+the snows.”
+
+It may be said that this theory of the canals on Mars is not
+universally accepted by astronomers, but is warmly disputed in some
+quarters. The _markings_ are undoubted; but some astronomers are
+inclined to think they are due solely to vegetal growth, and are not
+the result of human hands. The controversy still continues. Meanwhile,
+two satellites of Mars were discovered in 1877.
+
+
+
+
+JUPITER
+
+
+Jupiter is the largest of all the planets, having a diameter of about
+88,000 miles; it is only about 1,000 times smaller than the sun--that
+is, about 1,000 times larger than our earth. In volume, it is 1,300
+times larger than our globe. Gravitation must be enormous on its
+surface. Its density is however relatively low--being only about
+one-quarter that of the earth. It is thought to be a world of water and
+more or less dense gas. It is constantly covered by a thick blanket
+of clouds and vapors, making direct observation very difficult--as we
+saw was the case with some other planets. Immense as this planet is
+in size, it revolves at a tremendous speed--approximately 10 hours.
+Owing to its immense bulk, it cools more slowly than a body such as our
+earth. Consequently it will take tens of millions of years for it to
+cool sufficiently to permit life to become manifest upon its surface.
+Yet it may at that time! In a sense, Jupiter may be said to be a planet
+of the future; when our earth is cold and dead, Jupiter may be teeming
+with animate existence.
+
+Jupiter has 8 satellites, and a number of dark bands cross its surface
+from east to west. A certain dark spot upon its surface has caused
+great interest among astronomers, who are unable to determine its exact
+nature. This planet revolves round the Sun in rather more than 11¾
+years, at a mean distance of 483,000,000 miles.
+
+
+
+
+SATURN
+
+
+Saturn revolves round the Sun in 29½ years, at a mean distance of
+886,000,000 miles, in an orbit slightly eccentric. According to
+Barnard, its equatorial diameter is 76,470 miles, and its polar
+diameter 69,770, which figures imply a polar compression of 1/11. This
+planet is famous for the celebrated “ring” which surrounds it. As a
+matter-of-fact, when observed by means of high-powered telescopes, this
+famous “ring” is found to consist of a number of rings--three being
+clearly distinguishable. For long it was thought that these rings were
+vaporous; then that they were solid; but the present view is that they
+are composed of myriads of discrete particles of matter, so closely
+compacted together that to our remote eyes they appear as a solid mass.
+These rings are fairly broad, but relatively thin in diameter; they
+resemble a sort of huge disk. Perhaps 100 miles would be the thickness
+of these rings. Their diameter, however, is tens of thousands of miles
+in breadth. Owing to these rings, Saturn is one of the most beautiful
+of all the planets, when viewed through a high-powered telescope.
+
+Saturn doubtless has certain features in common with Jupiter, as to its
+physical appearance. The general hue of the planet is yellowish-white;
+it probably has no atmosphere, or at most a very tenuous one. It is
+attended by ten satellites, the largest of which is known as Titan,
+thought to be about 2,700 miles in diameter.
+
+
+
+
+URANUS
+
+
+This is the next to the last planet in our solar system. It is a large
+planet, having a diameter of about 31,000 miles. Uranus revolves
+round the Sun in rather more than 84 years, at a mean distance of
+1,781,000,000 miles. It is attended by four (or five) satellites. Belts
+and spots have been seen upon its surface, but relatively little is
+known concerning its physical conditions, owing to its great distance
+from us, and its relative smallness. This planet was discovered, as
+is well known, by Herschel, and was named after him, but its name was
+subsequently changed. (It is still mentioned as Herschel, in certain
+books upon Astrology.) It is probable that the temperature of Uranus
+is relatively low, owing to the small percentage of the sun’s rays
+which reach its surface. It has been calculated that its theoretical
+temperature is about 330° F.
+
+
+
+
+NEPTUNE
+
+
+The past century was remarkable for the discovery of this new planet:
+Neptune. How it was accomplished is a matter of great interest. In
+1820, it was found that Uranus was not following its computed path.
+Adams, of Cambridge, and Leverrier, of Paris, each independently took
+up this question, and, assuming that this perturbation was due to the
+presence of a planet still more remote from the sun (which had been
+hinted at in 1830 by Bessel) they set to work to calculate its position
+in the heavens. They finished this at about the same time, arriving at
+practically the same conclusions. Adams’ results were first submitted
+to the Astronomer Royal, who set them aside without consideration until
+too late. Leverrier sent his conclusions to a German astronomer, Galle,
+who found the planet the first evening he looked for it, September 23,
+1846.
+
+Neptune is the furthest known planet of our solar system; it is a very
+large body, having a diameter of about 37,000 miles. It revolves round
+the sun in an immense orbit which it takes 164 years to complete. Its
+mean distance from the Sun is nearly 2,800,000,000 miles--a majestic
+sweep through the heavens! Relatively little is known as to the
+physical conditions of Neptune, owing to its immense distance, and its
+relatively small size. At least one satellite is known to exist. The
+temperature on Neptune must be extremely low, owing to its distance
+from the sun, whose rays would be exceedingly feeble at that great
+distance.
+
+
+
+
+THE MINOR PLANETS
+
+
+Between Mars and Jupiter, a number of small bodies are known to exist,
+which have sometimes been dignified by the name of “minor planets.”
+They have also been called “Planetoids” and “Asteroids.” Special names
+have been given these individual small bodies--Eros, Ceres, Pallas,
+Vesta, Juno, etc. Eros passes, upon occasions, very close to our
+earth; again passing beyond the orbit of Mars. Several hundreds of
+these smaller planets are now known to exist--as though they were the
+remnants of some shattered world. These bodies are very small: Ceres,
+_e.g._, being about 250 miles in diameter; Pallas, 304 miles; Vesta,
+211 miles; while a number of the others are thought to be from 5 to 15
+miles in diameter.
+
+
+
+
+ARE THERE OTHER PLANETS?
+
+
+Inasmuch as some of the planets known to us have only been discovered
+so lately (relatively) the question has naturally been asked: “Why may
+there not be _other_ planets, beyond Neptune, still undiscovered?” It
+is a perfectly legitimate question, and no definite answer to this
+query can be given. It seems rather improbable that another planet
+will be discovered. However, it is a conceivable possibility, and M.
+Flammarion has stated that, in his estimation, such a planet probably
+exists--gravitating at a distance 48 times as great as the distance
+between the earth and the sun--that is to say, 7,500 million miles, in
+an immense orbit which it takes at least 330 years to accomplish. Proof
+as to the existence of such a planet has not, however, as yet been
+forthcoming.
+
+
+
+
+THE MOON
+
+
+The Moon is the Earth’s only satellite, and by far the nearest body in
+space to our Earth. Many astronomers are inclined to think that the
+Moon at one time formed a part of the Earth, but was wrenched away from
+it, leaving a huge cavity, which is now occupied by the Pacific Ocean.
+The Moon is a cold body, emitting no light or heat of its own; all the
+light which it seems to shed is entirely _reflected_ light--reflecting
+the sun’s rays, much as a mirror might reflect them; hence its
+beautiful silver color.
+
+In round numbers, the Moon is approximately 240,000 miles distant
+from us in space--the distance varying from 221,600 miles to 252,970
+miles--causing a corresponding variation in its apparent diameter and
+parallax.[A] The circumference of the Moon’s orbit is a little more
+than a million-and-a-half miles, and it travels through space with the
+velocity of 2,288.6 miles per hour, or 3,357 feet per second.
+
+[Footnote A: See page 58 for a definition of this term.]
+
+Our satellite always keeps the same face turned towards the Earth, so
+that we only see one side of it; the other side is forever hidden from
+the sight of man. However, the axis of the Moon tilts, in relation to
+the earth, and permits us to glimpse a little more of the surface both
+north and south, so that about five-eighths of the surface has actually
+been observed.
+
+The surface of the Moon has been subjected to intensive study, and its
+“geography” is now as well known as that of our own earth. Vast “seas”
+(i. e.) sea bottoms, mountain ranges, solitary mountain peaks, enormous
+craters, are readily observed, and modern telescopes have now brought
+the moon so close to us that it has been said that any body as high as
+the Woolworth Building, in New York, would cast a shadow which could be
+observed and noted.
+
+The fact that the same face of the Moon is always seen by man does not
+mean that this body remains stationary; it revolves on its own axis,
+from west to east, but this revolution occupies exactly one siderial
+month. The result is that the days and nights on the Moon, are many
+times the length of our days and nights. The surface exposed to the
+sun’s rays must get extremely hot, and, when deprived of these rays,
+extremely cold. It has been estimated that the mean temperature of the
+moon’s surface must approximate 200° F., during the “day” time, and
+approach the intense cold of inter-stellar space during the “night”
+(perhaps -250° C.). This would render life or vegetation of any kind
+very unlikely. However, Professor Pickering has lately asserted that
+vegetation _does_ apparently spring into being with extreme rapidity
+during the moon’s day time--evidently remaining latent during the
+intense cold of the “night.” (Some interesting material on this topic
+may be found in Shipley’s “Is the Moon a Dead World?” No. 557 of the
+present series.)
+
+The volume of the Moon is about one-fiftieth that of the earth, but
+its mass is only about one-eightieth that of our planet. The Moon
+is practically devoid of atmosphere, which is another reason why it
+cannot support “life,” in our sense of the word. Two theories have
+been advanced as to the absence of the moon’s atmosphere: (1) that it
+gradually combined, chemically, with the materials on its surface;
+and (2) that it gradually escaped into space, because of the low
+gravitational pull of the moon. There is no water on our satellite,
+which means that there is no ice and no snow. The moon being so much
+smaller than our earth, the pull of gravity is of course much less also.
+
+Yet it is well known that the tides, on the earth, are greatly
+influenced by the moon. Every atom composing our satellite must exert
+some subtle pull upon every atom of our oceans, in order thus to affect
+them. What is the nature of this attraction? Here we encounter the
+mystery of gravitation! This question must accordingly be postponed
+until we come to our discussion of that subject.
+
+One of the most remarkable and distinguishing characteristics of the
+moon consists in the so-called “lunar craters,” which appear to be
+immense, extinct volcanoes. More than 30,000 of these have now been
+mapped, varying in size from small hills to immense basins 50, 60, 100
+miles in diameter. Ptolemy is 115 miles across, while Theophilus is 64
+miles in diameter and 19,000 feet deep. The curious thing about these
+lunar craters is that they are unlike the hilly volcanoes known to us
+on our earth. They are rather huge circular pits, often square miles in
+extent, surrounded by a circular wall, and almost invariably having a
+single mountainous cone in the center.
+
+Various theories have been advanced by way of explanation of these
+craters. The most important of these are (1) that they represent
+extinct volcanoes; (2) that they indicate spots where masses of matter
+have dashed into the moon, from surrounding space; and (3) that
+they represent the surface of the moon, when it was a hot, seething
+mass--their resemblance to the “bubbles” formed at the surface of
+boiling glue, mud, etc., being pointed to as analogous. Unanimity of
+view does not exist even yet as to their origin.
+
+The ever-changing “phases” of the moon have been observed by
+generations of lovers. Thus, the new moon, full moon, etc., are
+commonplace sights. These apparent changes are, of course, due entirely
+to the relative position of the sun at the time. If the sun illumines
+the whole face of the moon, as viewed from our earth, we have full
+moon; if only a small portion of it, we see the first quarter, etc.
+The whole disk of the moon may always be seen, however, by careful
+observation. It is hardly necessary to say that the so-called “Man in
+the Moon” is a mind’s eye picture, created by the configuration of the
+various mountains, seas, etc., upon its surface.
+
+
+
+
+THE ORIGIN OF THE SOLAR SYSTEM
+
+
+Men in every age have speculated as to the constitution and origin
+of our world, and of the Universe in general. The first really
+detailed and scientific attempt was made, however, little more than a
+hundred years ago by Laplace--and subsequently known as the Laplacian
+hypothesis (1796).
+
+Concurrent with the establishment of new facts, there was a tendency,
+throughout the past century, to find some philosophic interpretation
+of the Universe and its structure; to ascertain, if possible, the
+“beginnings of things,” and explain them in some satisfactory manner.
+This has been considered as epoch-making in astronomical research as
+Darwin’s great theory of the Origin of Species was in biology. The
+history of the two theories has been similar also. Both have served a
+useful purpose; have helped to direct scientific thought for years; and
+both are now largely outgrown. Both were, however, of great value and
+of daring originality.
+
+Laplace assumed the primal existence of a glowing ball of gas rapidly
+revolving about an imaginary axis running through its center of
+gravity. During the process of cooling, this mass would contract, and a
+disk of gas would be thrown off in this manner; and hence a number of
+gaseous rings be formed, which would ultimately cool down and assume a
+spherical form. Laplace conceived that this process might be interfered
+with by internal accident and by comets from without.
+
+The first modifications of the theory were suggested by Sir Norman
+Lockyer, who proposed what is known as the meteoritic hypothesis in
+its place. The central idea of the theory was that--“All self-luminous
+bodies in celestial space are composed either of swarms of meteorites
+or of masses of meteoric vapor produced by heat.” The theory was based
+on spectroscopic analysis. It said that the original nebulæ were
+composed, not of gases, but of meteoric material and cosmic dust. This
+theory was never fully accepted in place of that of Laplace, however;
+but it paved the way for a more recent theory, which may be said to
+be satisfactory and more or less inclusive. This is known as _the
+planetesimal hypothesis_, and was advanced within the past few years
+by F. R. Moulton and T. C. Chamberlin, of the University of Chicago.
+At the present time, it may be said to be the accepted theory, so far
+as any such theories are accepted, since it accords with all the facts
+in a remarkable manner, and has been experimentally demonstrated. In
+outline, the theory is as follows.
+
+If examination of the nebulæ in the sky be made, out of 120,000 of
+them, nearly every one of them is found to be in the spiral form.
+So common and universal is this, indeed, that it was concluded that
+this must represent “some prevalent process in celestial dynamics.”
+This process is, according to Chamberlin, the actual formation of a
+solar system. As this spiral revolves, it accretes to itself various
+smaller bodies, with their gases, atmospheres, etc., and these become
+consolidated with the original body. As time went on, this spiral
+gradually tended to decrease its speed, but at the same time, continued
+to accrete bodies which came into contact with it in its flight
+through space. Thus, we have to imagine our world, not as an expanded
+molten mass which has continuously cooled and contracted, but, on the
+contrary, as a small lump of cold and solid fragments that, moving
+about in accordance with its attractions, continuously fed upon its
+surrounding assemblage of “smaller fry,” and thus grew to its present
+size. About the young earth so engaged it is possible to read, on the
+basis of the hypothesis, something of its early history.
+
+Thus we see that the old theory of Laplace has been reversed; and that,
+instead of a great central mass of moving, white-hot gas, we have a
+number of smaller bodies, all busily engaged in building up themselves,
+at the expense of the surrounding masses of still smaller matter--much
+as a crystal accretes to itself minute specks of crystalline matter
+from the solution in which it is immersed. This is the newest of the
+cosmological theories. According to it, all the planets might have been
+formed at the same time. This view of the formation of the universe
+opens up still wider problems, which are now the subject of keen debate.
+
+
+
+
+CONSTELLATIONS
+
+
+The ancients, when studying the heavens, saw all kinds of imaginary
+animals in the various star-groups, and named them accordingly. A
+constellation is really a group of stars, which seems to constitute a
+sort of system of its own. Thus, we find reference to the Great Bear,
+the Little Bear, the Bull, etc. It is difficult for the uninitiated
+to see the resemblances which the ancients did, in these various
+star-groups, and astronomical science has re-named them, as well as
+adding a large number of new constellations to those already known.
+
+Stars of the first six magnitudes (roughly) are visible to the
+unaided eye; those of lesser magnitude must be detected by the aid
+of telescopes. About 5,000 are thus visible; the number is increased
+according to the magnifying power of the telescope used, and it is
+estimated that there are more than 100,000,000 within the range of
+visual and photographic instruments!
+
+The names of a few of the best known constellations are as follows:
+Ursa Major (The Great Bear); Cassiopeia; Hercules; Scorpio (the
+Scorpion); Corona Borealis (The Northern Crown); Boötes (The Hunter);
+Leo (the Lion); Andromeda; Perseus; Auriga (The Charioteer); Taurus
+(the Bull); Orion; Canis Major (The Great Dog); Canis Minor (The
+Smaller Dog); Gemini (the Twins), etc.
+
+In these various constellations, certain noted stars are to be found.
+Thus, in Gemini, its two principal stars are Castor and Pollux. In
+Canis Major is Sirius. In Orion may be found Aldebaran and Betelgeuse.
+The Pleiades and Hyades groups are in Taurus. In Perseus is Algol. In
+Lyra is the first-magnitude star Vega. And so on.
+
+The “Big Dipper,” so-called, is part of the Constellation Ursa Major;
+and it is almost universally known that the Pole Star (Polaris) may
+readily be found by its means. The constellations must be traced and
+learned, one by one; but this the student must accomplish for himself!
+
+
+
+
+METEORS: “SHOOTING STARS”
+
+
+What are popularly known as “shooting stars” are not stars at all; they
+are really meteors which appear at altitudes of from 60 to 100 miles,
+as a rule, from the earth, and move over paths of 40 or 50 miles at a
+rate of from 10 to 50 miles per second.
+
+The light given out by meteors is due to their being heated by friction
+with the atmosphere. Falling from space, they become attracted by the
+earth’s gravitation, and fall towards it. Here they encounter the
+earth’s atmosphere, and their rapid passage through it creates terrific
+heat, which tends to consume them before they reach the face of the
+earth, turning them into gases, or causing them to fall gently as dust.
+This sudden flash is the “shooting star” in question.
+
+The number of such meteors is very great. It has been computed that
+between ten and twenty million strike the earth’s atmosphere daily.
+Occasionally, a large number of meteors fall together; and then we have
+a “meteoric shower.”
+
+
+
+
+METEORITES
+
+
+Occasionally, however, some of these bodies _do_ reach our earth,
+despite the friction and opposition of the earth’s atmosphere. Such
+bodies are called meteorites, siderites, or aerolites. Only a few of
+these are seen to strike the earth yearly, and it is a remarkable fact
+that, so far as we have any record, not one of them has ever struck a
+town or killed an individual. The outside of the meteorite during its
+passage through the air is subject to intense and sudden heating, and
+the rapid expansion of its surface-layers often breaks it into many
+fragments. The surface is fused and, on striking, cools rapidly. The
+result is that it has a black, glossy structure, usually with many
+small pits where the less refractive material has been melted out. Such
+meteorites may be seen in most large museums.
+
+
+
+
+COMETS
+
+
+During the past century, many of these “tramps of the solar system”
+have been discovered and their orbits computed. The “head” may range
+from ten thousand to a million miles, or more, while its “tail” may
+stream across the heavens for millions of miles. These comets’ tails
+always point away from the sun; and for long the reason for this was
+not known. It is now believed that this is due to light-pressure; the
+energy of the sun’s rays press this delicate matter outwards into
+space. (This theory has been elaborated at considerable length by the
+Swedish astronomer and chemist, Arrhenius.)
+
+Many readers of this little book will remember the excitement caused
+by Halley’s comet, which came relatively close to the earth in 1910,
+so that many persons thought there would be a collision, and were
+terrified accordingly! As a matter of fact, the tails of comets are
+usually of almost inconceivable tenuosity. Halley first observed this
+comet, computed its orbit and predicted the date of its return.
+
+Some comets have tails: others do not. Not much is known concerning
+the origin and destination of comets; where they originated, or how.
+They travel at tremendous speed over many millions of miles of space,
+returning after a few years, or after a lapse of several centuries.
+They are very striking looking, even when observed by the naked eye. A
+number of comets have been noted. The following are a few of the more
+remarkable comets which were observed during the past century:
+
+The Comet of 1811. This was visible for nearly a year and a half, and
+was carefully studied by William Herschel. Its tail was said to be
+nearly a hundred million miles long, and fifteen million miles broad.
+
+Encke’s Comet (1819). This comet is of extreme interest because of
+its change of volume. Moulton says: “On October 28, 1828, it was
+135,000,000 miles from the sun, and had a diameter of 312,000 miles.
+On December 24, its distance was 50,000,000 miles and its diameter was
+14,000 miles; while at its perihelion passage of December 17, 1838, at
+a distance of 32,000,000 miles, its diameter was only 3,000 miles.”
+
+Beila’s Comet (1826). This comet has a most interesting history. In
+1846 it was again seen; and a month later it had divided into two
+parts. They traveled along parallel orbits, some 160,000 miles apart.
+In 1852, they were seen to be 1,500,000 miles apart. Since then they
+have never been seen. They have, apparently, vanished from the face of
+creation!
+
+Donati’s Comet (1858). This comet was visible for more than nine
+months. Its tail was estimated as 54,000,000 miles long. Its period of
+revolution was more than 2,000 years.
+
+The Great Comets of 1880 and 1882. The latter of these passed through
+some hundreds of thousands of miles of the sun’s corona. Its orbit was
+not appreciably changed, but, after emerging, it was seen to possess at
+least five nuclei--showing the effect upon the comet of the disruptive
+forces through which it had passed.
+
+
+
+
+NEBULAE
+
+
+These are of especial interest, for the reason that they have played
+so large a part in forming cosmic theories--the Laplacian, the
+Planetestimal, etc. Nebulæ are of various kinds--“Annular Nebulæ,”
+resembling a flat, oval, solid ring, having a dark hole in the center.
+Then there are “Elliptic Nebulæ,” of varying degrees of eccentricity;
+the Great Nebula in Andromeda being a good example. (Numbers of
+isolated stars may be found within its limits.) “Spiral Nebulæ” are,
+perhaps, the best known of all, and their name accurately describes
+their appearance. There are also the so-called “Planetary Nebulæ,” as
+well as Nebulous Stars, Irregular Nebulæ, etc. Of late years, much
+interest has been centered upon the so-called “Dark Nebulæ.” Herschel
+had long before described various “holes in the heavens,” wherein no
+stars could be discerned. It is now believed that such spots do not
+represent “holes,” as much as dark masses of matter, which seem to
+blot out the bright stars behind them. The interested reader may refer
+to Hale’s “The Depths of the Universe” for additional information
+upon this topic, which is relatively new to astronomy. It is also
+interesting to note that the spectra of Nebulæ contain the bright
+lines in the green of a substance called “nebulium,” because it is not
+found except in nebulæ.
+
+
+
+
+THE MILKY WAY
+
+
+This is, in a sense, one vast nebula running right round the heavens
+in the form of a belt, or ring; its familiar resemblance to spilt milk
+being the origin of its popular name. To the naked eye, it appears
+merely a hazy band of light, but the telescope shows that it is made
+up of an enormous number of stars, millions of miles apart, but which
+can only be distinguished from one another by telescopic aid. It
+constitutes the so-called “Galaxy.” It seems to be spread out in the
+form of a vast disk, whose diameter is many times its thickness. Our
+solar system appears to be near the center of this vast system, and, as
+we penetrate further and further into space, it becomes apparent that
+fewer and fewer stars, and fewer and fewer nebulæ, seem to exist. Hence
+the limitation of the material Universe. The Milky Way is made up of
+thousands of millions of suns; yet their enormous distances make them
+appear to constitute one vast, luminous belt encircling our globe!
+
+
+
+
+THE NUMBER OF STARS
+
+
+When the heavens are viewed with the naked eye, a few hundred stars may
+perhaps be seen--some bright, some faint. Viewed through opera glasses,
+many more stars may been seen; while their number is again greatly
+increased by the use of a telescope. The larger and more powerful the
+telescope employed, the greater the number of stars thus discovered in
+the depths of space. The interesting question thus arises: What is the
+total number of stars in the entire firmament? Can they be estimated?
+And if so, what would their approximate number be?
+
+What we call “stars” are, of course, in practically all cases
+_suns_--often vastly larger and hotter than our own. These stars
+differ from one another in order of brilliance; some are brighter than
+others. They are accordingly classified according to their order of
+brilliance, and known as stars of the “First Magnitude,” of the “Second
+Magnitude,” etc., up to about the Seventeenth Magnitude. Any star of a
+given magnitude is, roughly, about two-and-a-half times as brilliant as
+one of the next lower order, and this variation holds throughout--each
+magnitude being that much greater in brilliance.
+
+The “magnitude” of the stars varies according to their light-giving
+power, and also their distance from us. One of the methods adapted to
+measure the magnitude is to compare its brightness with an artificial
+star, gradually cutting-off its light by means of neutral, tinted glass
+until the two are equal. The color of the star must be taken into
+account, in such measurements, the eye being more sensitive to some
+colors than to others.
+
+Now, it is an interesting and significant fact that the number of the
+stars decreases as their magnitude decreases; that is to say, the
+greatest number of stars are found of the first magnitude; a lesser
+number of the second; still less of the third, and so on (broadly
+speaking). After reaching the ninth magnitude, the number very rapidly
+diminishes. It has been calculated that there are about 120,000,000
+stars in the first 16 or 17 magnitudes. If the proportion were
+maintained throughout, however, there would be more than ten times that
+number. Some authorities have asserted that there are, roughly, half a
+billion stars of varying magnitudes in the heavens.
+
+
+
+
+THE POSITION OF OUR SOLAR SYSTEM
+
+
+It has been maintained that our solar system is at, or very near,
+the center of the whole Universe. Certain it is that the further we
+proceed into space, the less the number of stars encountered, which has
+given rise to the suspicion that their number is actually _limited_,
+and that the whole Universe consists of a sort of sphere, in which is
+enclosed all the stars that exist, and that, beyond this sphere, no
+stars whatever remain. No matter exists beyond this point! Such a view
+fits in rather well with Einstein’s conception of “curved space,” and a
+finite universe of infinite proportions! Of course, it is conceivable
+that, outside this vast system, another similar system may exist, and
+another and still another; but of such systems we know nothing, and it
+seems improbable that proof of their existence could ever be obtained
+by man. So far as we can tell, the universe is _One_, and the matter
+and energy of that one are limited.
+
+
+
+
+THE MOVEMENT OF OUR SOLAR SYSTEM
+
+
+It has been shown that our whole solar system is sweeping through space
+at the speed of about ten miles a second towards the stars in the
+constellation Hercules, and particularly towards Vega, one of its suns.
+However, Vega is likewise moving through space, so that by the time our
+sun reaches the spot now occupied by Vega (half a million years or so)
+Vega will no longer occupy that position, and no “collision” will take
+place in consequence! We shall not, in fact, pass very near that star.
+
+
+
+
+DISTANCES OF THE STARS
+
+
+Astronomical distances are so vast that they can only be measured in
+the mind relatively. The distances between the planets in our own
+solar system seem big enough; yet they shrink into insignificance when
+compared to the distances which separate our whole solar system from
+even the nearest of the stars. _Alpha Centauri_ is the nearest star,
+and it is separated from us by a distance 276,000 times as great as
+that which separates us from our sun. It is approximately 25 billion
+miles away. Traveling with the speed of an express train flung into
+space, at 40 miles an hour, towards the nearest star, without any
+stoppage or any slowing down, we should not arrive at our destination
+until after an interrupted flight of 75 million years. Yet this is
+our nearest neighbour! Only a _very few_ of the stars are within
+400,000,000,000,000 miles of the sun. The great majority of them are
+many times this distance from us.
+
+So vast are these distances that some simple means of expressing them
+on paper was sought. A “light Year” was finally decided upon as the
+_unit_ of measurement--that is, the distance which light would travel
+in one year, speeding at the rate of 186,000 miles a second. It has
+been estimated that many stars are one, two, three and perhaps five
+hundred thousand light-years distant from us in space. The interested
+reader may figure-out the number of miles this represents for himself!
+
+
+
+
+TEMPERATURE OF THE STARS
+
+
+Measurements which have been undertaken prove that the surface
+temperature of our Sun is between 5,000°C. and 7,000°C. It is
+thought that many stars are considerably hotter than this. We can
+form no adequate conception of such intense heat; all matter would
+be vaporized; yet, under the enormous pressures which must prevail,
+these vapors would in turn be converted into thick, semi-fluid
+substances--especially in the interior.
+
+
+
+
+FIXED STARS
+
+
+The so-called “fixed” stars are those which do not appear to change
+their positions in the heavens for long periods of time together. There
+are, of course, no “fixed” stars at all since every celestial body is
+moving with greater or lesser rapidity through space; but these stars
+are so far distant from us that such movements are inappreciable,
+even after long periods of time, and in spite of the most careful
+observations. In comparison with the more rapidly moving heavenly
+bodies, they do not appear to “move,” and have been denominated “fixed
+stars” in consequence.
+
+
+
+
+DOUBLE STARS
+
+
+A large number of stars appear single, when viewed by the naked
+eye, but when seen through a powerful telescope, are seen to be, in
+reality, two stars which revolve round one another. Many thousands of
+such double stars are now known to exist; indeed, apparently single
+stars have been found, upon closer examination, to be composed of
+a group of four or five or more stars--so that the name “multiple
+stars” has been given to such groups. They are near one another in the
+astronomical use of that word--though they may actually be hundreds
+of thousands, or millions of miles apart. Many of these double stars
+seem to be quite separate from one another. Others appear to have some
+physical connection. Those which are known to form systems are known as
+_binaries_.
+
+
+
+
+COLORED STARS
+
+
+Many of the double stars exhibit curious and beautiful phenomena
+of complementary colors. In such cases, the larger star is usually
+more or less reddish or orange, and the smaller one bluish-green or
+greenish-blue. Many of the double stars, on the contrary, are of the
+same color. There are white, red, blue, orange, green and yellow
+stars. The planets also vary greatly in color--Venus, e.g., being
+white, Mars reddish, etc. Inasmuch as the planets only reflect light,
+however, this is due to quite different causes; the other colored stars
+are self-luminous suns which emit light of their own.
+
+
+
+
+VARIABLE STARS
+
+
+In addition to variations in the color of stars, they also vary greatly
+in brilliance, and certain stars are much brighter at times than at
+others. In some cases these changes in brilliance are regular; in
+others, irregular. “Omicron,” for example, which, Bayer recorded in
+his Atlas in 1603, is a regular variable; its period of change is 331
+days, 8 hours; in other words, it reaches its greatest brightness about
+12 times in 11 years, when it sometimes attains the brilliancy of a
+star of the 2nd magnitude, at which brilliancy it remains stationary
+for about a fortnight. It then diminishes during about three months,
+until it sinks down to a star of magnitude 9½, or even becomes totally
+invisible. It remains in this condition for about 5 months, and then
+gradually recovers--during the next following 3 months--its maximum
+brilliancy. In other words, its brilliancy is absolutely periodic.
+Other variables are by no means regular, however, but “come and go” at
+different intervals.
+
+Various theories have been advanced by way of explanation--one of
+the simplest being that such stars are in reality double, one being
+luminous and the other not; and that, during their revolutions, the
+non-luminous star partially or totally eclipses the bright one, at
+stated intervals. The whole subject, however, is difficult, and much
+yet remains to be learned concerning these variable stars.
+
+
+
+
+TEMPORARY STARS
+
+
+From time to time, stars have suddenly appeared in the heavens, where
+no star existed before! Such stars have usually become increasingly
+brilliant for a short period of time, and then as suddenly died
+away again, leaving no trace of their existence behind them. These
+“new stars” for long puzzled astronomers. The theory often advanced
+to explain them is that some distant star has “exploded,” and the
+increasing brilliance which we see is the result. If such were the
+case, its sudden dimming-down and disappearance would be quite
+intelligible--as would be its sudden appearance. A large number of
+such stars have now been recorded, and their existence is no longer in
+doubt. In some cases, they have remained visible for weeks or months
+before their final disappearance.
+
+
+
+
+STAR GROUPS--CLUSTERS
+
+
+Here and there throughout the sky are places where the brighter stars
+seem to be clustered. These families of stars are of such magnificent
+proportions as to stagger the imagination. Among the best known are the
+Pleiades, the Hyades, Coma Berenices and Orion. Although they appear to
+us very close together, they are not really so, being usually several
+hundreds of thousands of miles apart. Many of these star-groups
+are irregular; but numbers of them constitute clusters, which are
+of various sizes and shapes. Perhaps the most interesting are the
+so-called “globular clusters,” because they present the appearance of
+stars having been massed together as globes. Some of them contain five
+or six thousand stars. Although they appear to us so close together,
+it has been calculated that, in a cluster containing 5,000 stars the
+average distance of the stars from one another would be 30,000 times
+the distance of the sun from the earth! The vast distances of space
+considered in astronomy may perhaps be realized by this fact--when
+it is considered that such a cluster appears to us as a single star,
+only capable of being separated into its component parts by means of
+high-powered telescopes!
+
+
+
+
+ECLIPSES
+
+
+The total eclipse of the Sun, January 24, 1925, brought the subject of
+eclipses to the public attention as never before, and many thousands
+of persons watched that beautiful and impressive sight through smoked
+glasses or strips of film.
+
+When we speak of eclipses, we usually mean an eclipse of either the Sun
+or the Moon. How are such eclipses caused?
+
+A total or partial eclipse of the sun is caused by the moon passing
+between the earth and the sun, the three celestial bodies forming, as
+it were, a straight line. The sun is then shut-off from the vision
+of the inhabitants of our globe over a certain, limited area of its
+surface. The shadow cast by the moon falls across the earth.
+
+But how is the moon eclipsed? Certainly the sun does not pass between
+the moon and the earth, on such occasions! What causes the moon to be
+eclipsed?
+
+The answer is as follows: Inasmuch as both the earth and the moon are
+illuminated by the sun, they both cast long shadows into space, as any
+solid body does, when held in front of a strong light. The earth’s
+shadow trails away for thousands of miles into space. Into this shadow
+the moon enters, and when it does so, it becomes eclipsed--totally or
+partially, as the case may be. Total eclipses are instances when the
+whole surface of the celestial body is apparently covered; partial
+eclipses are those in which only a portion of the body is dark--the
+remainder being still visible.
+
+In addition to eclipses, two other astronomical phenomena of interest
+should here be mentioned: _Transits_, and _Occultations_. By “transit”
+is meant the passage of some other heavenly body between ourselves and
+the sun. Thus, Mercury and Venus, both lying nearer the sun than the
+earth, occasionally pass in front of it. We then have a transit of
+Venus, or a transit of Mercury, as the case may be.
+
+By “Occultation” is meant the hiding of one heavenly body by
+another--as when the moon hides some other planet or star, or one
+planet hides another planet or star. The three bodies are then “in
+line” as before. Of course, all eclipses represent instances of
+Occultation.
+
+
+
+
+TELESCOPES
+
+
+Telescopes are of relatively recent origin; the ancients were forced
+to make their observations without them, which makes some of their
+conclusions all the more remarkable. There is considerable evidence
+that the builders of the Great Pyramid employed the “Grand Gallery” for
+astronomical observations (see “The Great Pyramid of Egypt,” in the
+present series), and other devices were employed. But no telescopes of
+any great power of magnification existed before the last century, while
+our present marvelous instruments of precision are the evolution of the
+present century.
+
+Telescopes are of two kinds: refracting and reflecting. Any small
+telescope exemplifies the former; the incoming light-rays are focussed
+by a series of lenses, and directly observed by the eye. In the
+employment of reflecting telescopes, however, another principle is
+employed: the incoming light-rays are caught and reflected by means
+of a curved mirror, and focussed on a lens, which in turn is inserted
+in an elaborate eye-piece, in which the light-rays are magnified and
+measured. Some of the modern instruments have a forty or more inch
+aperture, and are capable of enormous powers of magnification.
+
+
+
+
+THE SPECTROSCOPE: SPECTRUM ANALYSIS
+
+
+For more than two thousand years, astronomy remained a purely
+mechanical and mathematical science, being limited to observations and
+deductions therefrom; but in 1860 the method of spectrum-analysis was
+discovered. This was a most revolutionary discovery, inaugurating, as
+it did, the whole science of astro-physics; and enabling us to know as
+much of the physics and chemistry of distant stars and nebulæ--their
+nature, constitution, and temperature--as we know of the planets of our
+own system! Even the existence of otherwise invisible stars has been
+demonstrated in this manner--their orbits, rate of motion, and mass.
+The science of astro-physics is now one of the most exact in the whole
+realm of science; and has only been rendered possible by the invention
+of the spectroscope. As this instrument plays such an important part
+in all astronomical research, a brief explanation of the instrument
+becomes necessary.
+
+If a ray of sunlight be passed through a glass prism, the ray is split
+up into its primary colors; so that, instead of a single spot of white
+light being visible a narrow band of brilliant colors is seen--ranging
+from red to violet. But this is not the most important part of the
+discovery. When this spectrum was closely examined, it was found to
+be crossed by numerous black bands of various thicknesses. Sometimes
+these occurred in groups, sometimes singly. By enlarging the spectrum
+by passing it through several prisms, as many as 3,000 of these bands
+could be counted. The nature and explanation of these strange bands
+of blackness remained long uninterpreted, however. It remained for
+Kirchoff, in 1860, to discover their uses and significance.
+
+Briefly, it is this. The chemical elements, when heated to a state
+of incandescence, present each one its own characteristic spectrum;
+each one has its own peculiar markings, or band of lines. No two
+elements are exactly like in their bands, as shown in the spectrum.
+Hence, whenever that particular marking is observed, it becomes certain
+that that element, and none other, is present. These spectra are very
+varied; iron, for example, has more than 2,000 such bands, while lead
+and potassium have but one each.
+
+In this way--all the chemical elements having been studied, and their
+characteristic bands known--it became possible to explore the stars,
+planets and suns, and discover their chemical composition. For, no
+matter where an element was discovered--on this earth or on the
+remotest star--it would always cast its particular spectrum, when thus
+examined. The effect of all this upon astronomy can be perceived at
+once. Not only the heavenly bodies known to us, but those which have
+never been seen by human eye--even when aided by the most powerful
+telescopes--can be studied and their chemical composition and structure
+accurately determined. Here is progress indeed!
+
+All this becomes the more remarkable when we stop to consider the
+immense distances of space, and how widely separated the heavenly
+bodies are from one another. This may, perhaps, be shown by one or two
+illustrations. We are, roughly, about 93,000,000 miles from our own
+sun. Now, the majority of the stars we see are suns, like ours. The sun
+next removed from us in space is about 275,000 times as far from us as
+we are from our sun. The orbit of Halley’s comet, of which so much has
+been written lately, is some 3,280,000,000 miles in length; and this
+sporadic body, coursing through space at a speed 50 times greater than
+a rifle bullet, takes 75 years to complete its circuit. The nearest
+star has been calculated to be nearly 25 trillion miles away; while
+some of the stars are 40 times as far from us as that!
+
+
+
+
+PHOTOGRAPHY
+
+
+The second great engine of astronomical research, that has been added
+during the past century, is _photography_. By this means exact maps
+may be taken of the heavens at any hour of the night, and the precise
+position of thousands of stars determined with the utmost exactitude.
+A chart of the heavens, made in this manner, is not only more complete
+but more accurate than the combined observations of any number of men
+could possibly be. Moreover, the photographic plate will record the
+existence of stars which cannot be seen even with the aid of the most
+powerful telescopes. This is due to the fact that the plate gradually
+collects light, and its _cumulative_ effect is noticeable, when its
+_immediate_ effect cannot be perceived. This power of photographic
+plates is most valuable, and cannot be duplicated in any other manner.
+We are assured on good authority that “an ordinary good portrait camera
+with a lens three or four inches in diameter, if properly mounted so
+that an exposure of several hours can be made, will show stars so
+minute that they are invisible even in the great Lick telescope.” An
+international photographic chart of the heavens is now under way,
+which, when finished, will represent an accurate catalog of every
+visible sun, star, and planet, in the sky. After this, any unusual body
+should be quickly discovered.
+
+But photography is employed not only for mapping out the heavens, but
+for reaching the farthest stars. The moon and the sun have both been
+photographed repeatedly, and with most instructive results. The first
+good pictures of the moon were made by Dr. John W. Draper of New York
+City, in March, 1840. His son, Dr. Henry Draper, succeeded him in this
+work, and his photographs were considered the best until Rutherfurd
+began his remarkable work in 1865. After this, much important work
+was done in the Lick observatory, and elsewhere. The first picture of
+the sun was taken in 1845, by Fizeau and Foucault, on a daguerreotype
+plate. Sun spots, total eclipses, etc., are now studied in great detail
+by this means.
+
+
+
+
+THE TIDES
+
+
+Every particle of matter attracts every other particle of matter
+throughout the entire Universe. The Sun and the Moon both exert a
+definite pull upon the earth; the moon particularly, being the earth’s
+satellite, is (so to say) held in place by the earth. The moon,
+exerting this definite pull, naturally influences the water of the
+earth most of all, because water is a fluid, mobile body. A heaping-up
+of the water then occurs--“high tide.” But the moon also attracts the
+earth to some extent; and the consequence of this is that the water
+on the opposite side of the globe is, as it were, left behind, which
+causes a heaping-up of the water there also. Hence, there are two high
+tides daily, with an interval of 12 hours between them, on opposite
+sides of the globe.
+
+When the sun and moon pull together, we have the highest tides--“spring
+tides.” When they do not pull together (being in different parts of the
+heavens) we have only the surplus pull of the moon over the sun, and
+the tides are consequently not so high. These are the “neap tides.” All
+tides act as a sort of check or brake upon the rotation of the earth on
+its axis--tending to slow down its speed to some extent. “Tidal waves”
+are due to a combination of special causes.
+
+
+
+
+GRAVITATION
+
+
+The mysterious influence or “pull” which various celestial bodies
+exert upon one another is known as gravity or gravitation. We know
+that masses of matter attract one another according to their size;
+the larger the body, the greater the force exerted, etc. Further, the
+influence decreases according to a definite law--according to the
+square of the distance between the two bodies. The innermost nature
+of gravitation is still largely a mystery--though various ingenious
+theories have been advanced in order to explain it. (See my article
+in “The Monist,” for July, 1913, and pp. 44-46 of “New Discoveries
+in Science” in the present series.) Gravitation is supposed to act
+throughout the whole Universe, so that all celestial bodies mutually
+influence one another, to some extent. Its speed, mode or action, etc.,
+as well as its essence or true nature are, however, unknown even yet;
+they are still unsolved mysteries!
+
+
+
+
+THE ETHER
+
+
+At all events, gravitation is thought to act through, or by means of,
+the Ether--the nature of which is still another mystery! Lodge, in his
+“Ether of Space,” has given some interesting figures as to the enormous
+strain which the ether must be supposed to transmit or carry. Lack
+of space, however, prevents a further discussion of this interesting
+question; a brief summary may be found on pp. 53-55 of my book on
+“Chemistry for Beginners,” in the series of Blue Books. For our present
+purposes, it need only be said that the ether is the only hypothetical
+connecting-link between celestial bodies--since there is no air or
+atmosphere in interstellar space. And it is across or by means of this
+ether that gravitation must be exerted.
+
+
+
+
+ATOMIC ANALOGIES
+
+
+Recent investigations of the innermost structure of the atom have
+shown us that it is probably constituted on very much the same plan
+as our solar system--a central “sun” or proton, round which revolve
+the negative planets or “electrons.” This question I have treated more
+fully in my “Chemistry for Beginners,” pp. 42-44, to which the reader
+is referred.
+
+
+
+
+THUNDER AND LIGHTNING
+
+
+The lightning flash is merely a huge electric spark, such as may
+be seen between the terminals of any electric machine. In cases of
+flashes, or forked lightning, this “spark” is seen directly. Sheet
+lightning is observed when the original flash is hidden behind clouds,
+and only its reflection or effects are seen. The rumbling of thunder is
+due to the reverberations and echoes of the original “peal.” The peal
+is thought to be due to the sudden rushing together of the molecules of
+the upper atmosphere, which have been rent asunder by the flash--a sort
+of vacuum created. Camille Flammarion has written an interesting book
+on “Thunder and Lightning,” which may be consulted for further details.
+
+
+
+
+FIREBALLS
+
+
+These are virtually the same as “shooting stars” (_q.v._,) and no
+essential difference can be pointed to, as to their origin or nature.
+They are not mere “blobs” of lightning, but solid bodies which
+sometimes burst, with a great noise--though they are usually noiseless.
+Many of them appear to be pear-shaped, but they may be seen to change
+their size and shape during the period of visibility. Fireballs are
+often accompanied by a train of sparks.
+
+
+
+
+ATMOSPHERIC ELECTRICITY
+
+
+The surface of the earth is constantly charged with negative
+electricity of a static character. The upper atmosphere is usually
+charged positively, though, this may vary according to circumstances.
+The earth and upper air thus resemble two sheets of tin-foil, with
+the air an imperfect dialectric between them. This may be broken
+down, especially in wet or damp weather. The effects upon the mental
+and physical health are often very noticeable (see Dexter: “Weather
+Influences,” etc.)
+
+
+
+
+THE EARTH’S MAGNETISM
+
+
+It has long been known that the magnetic pole does not coincide with
+the North Pole (or South Pole). The compass points to the magnetic
+north pole, and not to the true north pole. Lines of magnetic force
+seem to envelop the earth, terminating at the north and south poles,
+respectively. Although this is purely a terrestrial phenomenon, it is
+necessary to mention it here, since it has enabled us to explain, very
+largely, the remarkable manifestation known as
+
+
+
+
+THE AURORA BOREALIS
+
+
+This is usually seen in northern climes, and the reason for this is
+now clear. We know that the corpuscles discharged from a Crookes tube
+are deflected by a magnet. These corpuscles are discharged in immense
+numbers by the sun, and rain upon our earth. Now, the earth is a
+magnet, and these corpuscles are caught by the lines of force girdling
+our earth, and carried towards the poles, where they find themselves
+in an atmosphere comparable with high vacua. They then begin to give
+out the shifting and darting lights characteristic of the cathode rays,
+causing a certain luminosity. These darting and shifting lights would,
+on this theory, account for the Aurora Borealis--which is also known to
+vary with the number of sun-spots.
+
+
+
+
+TIME: MEASUREMENT OF:
+
+
+Our divisions of time are purely arbitrary, and are all based upon
+the revolution of our earth upon its axis, which thus constitutes
+a gigantic clock. All other clocks, watches, etc., are adjusted
+accordingly. This is really our only way of measuring time; subjective
+feelings are very illusory, and have to be checked-up by other means.
+The solar day is the basis of all our calculations--a month, a year,
+etc., being only so many days in length. Our earth, therefore, is the
+clock by which we measure the time of the Universe!
+
+
+
+
+SPACE: MEASUREMENT OF:
+
+
+The measurement of space is always a difficult problem, even for
+near-by objects (see my “Psychology for Beginners”). When applied to
+celestial bodies, it becomes immensely complicated, and the only wonder
+is that such apparently accurate measurements have in fact been made!
+Such measurements cannot, of course, ever be made _directly_, but must
+depend upon trigonometry and abstruse mathematical calculations. Most
+of them are based upon the following principles: If we observe a
+distant object from two different points-of-view, at a known distance
+apart, the angle formed by imaginary lines running from the object to
+one position, and to the other, can readily be calculated. Knowing
+this angle, much can be ascertained as to the size, distance, etc., of
+the distant body. If a distant star be viewed from opposite sides of
+the earth, we have here a known base-line of slightly more than 8,000
+miles. But this is altogether too small for astronomical distances! A
+much longer base-line must be sought. Accordingly, observations are
+made of a distant star when the earth is (so to say) “north” of the
+sun, and further observations of the same star when the earth is (so
+to say) “south” of it--six months later, when the earth has traveled
+half-way through its orbit round the sun. The diameter of the earth’s
+orbit being known (186,000,000 miles, almost) we have here a base-line
+of this size for use in our measurement of the angle and subsequent
+calculations. Immense as this base-line is, however, it is too small
+for our purposes, for so immense are astronomical distances, that _no
+change whatever_ can be observed in the relative positions of certain
+fixed stars--even when studied from such different positions in space!
+In other words, the star is so far distant that, when viewed from two
+positions in space, distant from one another nearly one hundred and
+eighty-six million miles, it appears to occupy the same position! But a
+mere summary of this question, and its details would involve an entire
+volume in itself!
+
+
+
+
+THE INTERNATIONAL DAY LINE
+
+
+Inasmuch as our earth revolves on its axis, a new day is beginning
+at some different moment all round the world. This being the case,
+how are we to fix some definite and official “starting point” for our
+day--since the day officially begins at midnight, and not at sunrise?
+To determine this, an arbitrary International Day Line has been drawn,
+on the 180th meridian--just half way round the globe from Greenwich.
+Fortunately, this falls in the Pacific Ocean, where there is almost
+no land. When the sun crosses this line, a new day begins. I have
+explained this more fully in my book “New Discoveries in Science” in
+the present series (pp. 40-42).
+
+
+
+
+CALENDARS, ETC.
+
+
+Our year is a little more than 365 days in length--in fact, nearly
+365¼. Because of this fact, an extra day accumulates every four years;
+and to include this we add this extra day to February every “leap
+year.” In this way, our celestial bookkeeping is kept fairly accurate.
+Twelve months of 30 days each would give 360 days, with five days over.
+It was, however, found that five days was not enough, while five and a
+quarter was too much. It is interesting to note that Hipparchus, who
+flourished in the 2nd century B. C., worked on this problem, and fixed
+5 days and 55 m., as the time required--a truly remarkable achievement,
+since it has since been found to be accurate to within less than six
+minutes.
+
+
+
+
+CURVED SPACE
+
+
+This, and various other problems connected with the Einstein theories
+may be found treated in No. 408 of the present series, “An Introduction
+to Einstein,” by William F. Hudgings.
+
+
+
+
+THE TEMPERATURE OF SPACE
+
+
+The Earth is warmed by the sun’s rays, some of which are absorbed,
+while some are reflected. But these rays themselves possess no
+“heat”; they are merely minute vibrations in the ether. Heat is only
+present when they strike some solid body. Consequently the vast
+inter-stellar spaces are tremendously cold--probably at or about
+absolute zero (-273.10°C). Our earth is not heated directly, as a man
+is heated by standing in front of a blazing fire; but only by means
+of electro-magnetic undulations, which traverse millions of miles of
+space, colder than death, without heating them!
+
+
+
+
+LIGHT IN SPACE
+
+
+Space is also intensely dark; no light exists there save the faint
+twinklings of distant stars. The sun illumines our earth, because its
+rays are reflected from its surface; but space itself is intensely
+black, just as it is intensely cold It is a “cold world” indeed, once
+we have stepped off the little planet on which we dwell!
+
+
+
+
+LIFE IN SPACE
+
+
+All this being so, life in any form cannot very well exist in
+space--since the conditions for its existence are altogether absent.
+Arrhenius has, however, suggested, that the “germs of life” might
+possibly be carried across millions of miles of space on dust
+particles, propelled by the energy of light. This, however, is a pure
+theory, which has so far received no official proof.
+
+
+
+
+THE CAUSES OF AN ICE AGE
+
+
+We know that our Earth has passed through several ice ages, in the
+past, and various astronomical theories have been advanced in order to
+explain this fact. Perhaps the most ingenious of these is that advanced
+by Sir Robert Ball (see his “The Cause of An Ice Age”). Very briefly,
+it is that the eccentricity of the earth’s orbit and the tilting of
+the polar axis causes an ice age, or the reverse. If the northern axis
+is tilted towards the sun, when nearest to it (so to say), then the
+northern hemisphere will enjoy a genial climate, and if the southern
+axis be thus tilted, the reverse conditions will prevail. This, and
+various other theories have, however, been discussed by Finger in his
+book on “The Ice Age,” in the present series, No. 327.
+
+
+
+
+WHY DO STARS “TWINKLE”?
+
+
+When we look at a star near the horizon, we at once notice that it
+twinkles, or “scintillates,” especially in the winter time. The
+phenomenon is purely atmospheric, and is due to waves of air of unequal
+density sweeping across the line of sight. When viewed through a
+telescope, this is sometimes magnified into actual dancing.
+
+
+
+
+WHY DOES THE MOON SOMETIMES APPEAR LARGER?
+
+
+It is well known that the moon often appears larger when rising or
+setting--i. e., near the horizon, than when it is overhead. The same
+is true of the Sun. It is hardly necessary to say that these celestial
+bodies have not _actually_ increased or decreased in size! Why, then,
+should we perceive them larger at some times than at others?
+
+The reason for this is two-fold; psychological and optical. In the
+first place, the Heavens do not appear to us quite round, but somewhat
+flattened out, like a watch-glass. Hence the moon appears to be much
+further away when it rises than it does when it is overhead, with
+nothing between. The moon near the horizon is apparently larger because
+it seems further away. The second reason is that the refraction of the
+earth’s atmosphere gives this illusion of increased size.
+
+
+
+
+ARE THE PLANETS INHABITED?
+
+
+This is a much-disputed point! Various astronomers (Schiaparelli,
+Lowell, etc.) have contended that they have almost indubitable evidence
+that Mars is inhabited by living beings like ourselves; other
+equally competent astronomers assert the contrary. Certainly, none
+of the planets of our own solar system, with the possible exceptions
+of Mars and Venus, could possibly be inhabited. That is universally
+granted. And we have no _direct_ evidence of any other inhabited
+worlds throughout space. Analogy, however, forces us to believe that,
+of the millions of suns blazing in the heavens, many of them must be
+attended by a planetary system such as ours; and if such be the case,
+there is no reason why life should not originate and thrive thereon as
+well as upon our own planet. We have, however, no means of proving or
+disproving this directly.
+
+In our own system, Venus and particularly Mars offer possibilities.
+Venus probably always turns one face towards the sun, so that this
+side would be tremendously hot, while the other side would be frozen
+in perpetual ice. Mars is a possibility; and, as we know, great
+controversy has raged regarding the habitability of this planet, and
+as to its “Canals.” The interested reader may refer to Lowell’s “Mars
+as the Abode of Life,” and “Mars and Its Canals” for the affirmative,
+and to Maunder’s “Are the Planets Inhabited?” for the negative, side of
+this question.
+
+
+
+
+A FEW DEFINITIONS
+
+
+What “Parallax” means. Since the earth revolves round the sun, the
+stars are apparently in slightly different directions from it at
+different times of the year. The difference in direction of a star as
+seen from two points on the earth’s orbit which are separated by the
+mean distance to the sun is the _parallax_ of the star. In other words,
+the parallax of a star is the angle subtended by the major semi-axis of
+the earth’s orbit, as seen from the star.
+
+The “Orbit” of a moving body is its more or less circular passage
+through space, usually around another larger body, as our earth
+revolves round the sun. The “eccentricity” of the orbit consists in the
+fluctuations or variations from its exact path.
+
+The “Ecliptic” System. If we could see the stars near the sun, we
+should find that the Sun apparently moves eastward among them,
+completing one revolution in a year. Tracing such a path, it will be
+found that it more or less coincides with the celestial equator. The
+equator and the ecliptic intersect at two points; these points are the
+“equinoxes” the _vernal_ equinox being the one at which the sun crosses
+the equator from south to north, and the _autumnal_ equinox the other
+one.
+
+“Satellites.” These are smaller bodies which revolve round large ones,
+and, so to say, attend them. All except two of the planets are known
+to have satellites revolving round them, just as they revolve round
+the sun. Mercury and Venus have none; the earth has the moon; Mars has
+two little moons, only a few miles in diameter; Jupiter has four large
+satellites and four small ones; Saturn has ten, one of which is larger
+than Mercury; Uranus has four satellites, and Neptune one.
+
+The “Planetoids.” Between Mars and Jupiter a number of small bodies
+have been discovered, moving in a regular orbit; these have been
+called planetoids. If some planet has once occupied this mid-way
+position, and subsequently exploded, the fragments would occupy the
+position occupied by the planetoids. Whether or not this is their
+origin is a disputed point, which it would take us too far afield to
+consider here. They suggest the possibility.
+
+“Planets.” These are the bodies revolving round a central sun. Aside
+from those constituting our own solar system, we see no planets in
+space; we see suns, or stars; but if the latter have planets attendant
+upon them, we cannot see them.
+
+The point of the moon’s orbit nearest the earth is called the
+_perigee_; the furthest point, the _apogee_.
+
+
+
+
+TRANSCRIBER’S NOTES
+
+
+Author’s spelling of “dialectric” has been retained.
+
+Inconsistencies in hyphenation have been left unchanged.
+
+Typos corrected:
+
+Title page: missing opening quote in “Psychology for Beginners”
+
+Page 13: “concenses” to “consensus”
+
+Page 17: “equitorial” to “equatorial”, "Myriads" to "myriads"
+(lowercase)
+
+Page 49: “on my book” to “of my book”
+
+Page 54: “litle” to “little”
+
+Page 59: “Unanus” to “Uranus”
+
+*** END OF THE PROJECT GUTENBERG EBOOK 78112 ***
diff --git a/78112-h/78112-h.htm b/78112-h/78112-h.htm
new file mode 100644
index 0000000..4ad8940
--- /dev/null
+++ b/78112-h/78112-h.htm
@@ -0,0 +1,3157 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <meta name="format-detection" content="telephone=no,date=no,address=no,email=no,url=no">
+    <title>
+      Astronomy for Beginners | Project Gutenberg
+    </title>
+    <link rel="icon" href="images/cover.jpg" type="image/x-cover">
+    <style>
+
+body {
+    margin-left: 10%;
+    margin-right: 10%;
+}
+
+h1,h2,h3,h4,h5,h6 {
+    text-align: center; /* all headings centered */
+    clear: both;
+}
+
+p {
+    margin-top: .5em;
+    text-align: justify;
+    margin-bottom: .5em;
+}
+
+.p6       {margin-top: 6em;}
+
+hr {
+    width: 33%;
+    margin-top: 2em;
+    margin-bottom: 2em;
+    margin-left: 33.5%;
+    margin-right: 33.5%;
+    clear: both;
+}
+
+hr.chap {width: 65%; margin-left: 17.5%; margin-right: 17.5%;}
+@media print { hr.chap {display: none; visibility: hidden;} }
+
+div.chapter {page-break-before: always;}
+h2.nobreak  {page-break-before: avoid;}
+
+table {
+    margin-left: auto;
+    margin-right: auto;
+}
+table.autotable    { border-collapse: collapse; }
+table.autotable td,
+table.autotable th { padding: 0.25em; font-weight: normal; }
+
+.tdl      {text-align: left;}
+.tdr      {text-align: right;}
+
+.pagenum {
+    position: absolute;
+    left: 92%;
+    font-size: small;
+    text-align: right;
+    font-style: normal;
+    font-weight: normal;
+    font-variant: normal;
+    text-indent: 0;
+} /* page numbers */
+
+blockquote {
+    margin-top: 0;
+    margin-bottom: 0;
+    margin-left: 5%;
+    margin-right: 10%;
+}
+
+.center   {text-align: center; text-indent: 0;}
+
+/* Footnotes */
+
+.footnote         {margin-left: 10%; margin-right: 10%; font-size: 0.9em;}
+
+.footnote .label  {position: absolute; right: 84%; text-align: right;}
+
+.fnanchor {
+    vertical-align: super;
+    font-size: .8em;
+    text-decoration:
+    none;
+}
+
+/* Transcriber's notes */
+.transnote {background-color: #E6E6FA;
+    color: black;
+    font-size:small;
+    padding:0.5em;
+    margin-bottom:5em;
+    font-family:sans-serif, serif;
+}
+
+.ph1 {
+    text-align: center;
+    font-size: xx-large;
+    font-weight: bold;
+}
+.ph2 {
+    text-align: center;
+    font-size: x-large;
+    font-weight: bold;
+}
+.transnote {
+    margin-left:17.5%;
+    margin-right:17.5%;
+}
+
+.x-ebookmaker .ep6 {margin-top: 6em;}
+
+li { margin-top: 0.25em; margin-bottom:0; line-height: 1.2em; }
+    </style>
+</head>
+<body>
+<div style='text-align:center'>*** START OF THE PROJECT GUTENBERG EBOOK 78112 ***</div>
+
+
+<p><span class="pagenum" id="Page_1">[Pg 1]</span></p>
+
+
+<p class="center">
+  <span style="display:inline-block;">LITTLE BLUE BOOK NO.<br>
+  <small>Edited by E. Haldeman-Julius</small></span>
+  <span style="display:inline-block; margin-left:0.5em; vertical-align:top; font-size:1.8em">895</span>
+</p>
+
+<h1>
+Astronomy for<br>
+Beginners
+</h1>
+
+
+<p class="ph2">Hereward Carrington, Ph.D.</p>
+
+<p class="center">Author of the following Little Blue Books: No.
+679, “Chemistry for Beginners;” No. 491, “Psychology
+for Beginners;” No. 419, “Life: Its
+Origin and Nature;” No. 524, “Death and
+Its Problems;” No. 493, “New Discoveries
+in Science;” No. 409, “Great
+Men of Science;” etc., etc....</p>
+
+<p class="center p6">HALDEMAN-JULIUS COMPANY
+GIRARD, KANSAS</p>
+
+
+<p><span class="pagenum" id="Page_2">[Pg 2]</span></p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p class="center ep6">
+Copyright, 1925,<br>
+Haldeman-Julius Company
+</p>
+
+<p class="center p6">
+PRINTED IN THE UNITED STATES OF AMERICA
+</p>
+</div>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_3">[Pg 3]</span></p>
+
+
+  <h2 class="nobreak" id="CONTENTS">
+    CONTENTS.
+  </h2>
+</div>
+
+<table class="autotable">
+<tr>
+<th class="tdl">
+</th>
+<th class="tdr">
+Page
+</th>
+</tr>
+<tr>
+<td class="tdl">
+Introductory
+</td>
+<td class="tdr">
+<a href="#INTRODUCTORY">5</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Astrology
+</td>
+<td class="tdr">
+<a href="#ASTROLOGY">7</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Solar System
+</td>
+<td class="tdr">
+<a href="#THE_SOLAR_SYSTEM">8</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Sun
+</td>
+<td class="tdr">
+<a href="#THE_SUN">9</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Mercury
+</td>
+<td class="tdr">
+<a href="#MERCURY">11</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Venus
+</td>
+<td class="tdr">
+<a href="#VENUS">12</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Earth
+</td>
+<td class="tdr">
+<a href="#THE_EARTH">13</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Mars
+</td>
+<td class="tdr">
+<a href="#MARS">13</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Jupiter
+</td>
+<td class="tdr">
+<a href="#JUPITER">16</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Saturn
+</td>
+<td class="tdr">
+<a href="#SATURN">17</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Uranus
+</td>
+<td class="tdr">
+<a href="#URANUS">18</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Neptune
+</td>
+<td class="tdr">
+<a href="#NEPTUNE">18</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Minor Planets
+</td>
+<td class="tdr">
+<a href="#THE_MINOR_PLANETS">19</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Are There Other Planets?
+</td>
+<td class="tdr">
+<a href="#ARE_THERE_OTHER_PLANETS">20</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Moon
+</td>
+<td class="tdr">
+<a href="#THE_MOON">20</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Origin of the Solar System
+</td>
+<td class="tdr">
+<a href="#THE_ORIGIN_OF_THE_SOLAR_SYSTEM">24</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Constellations
+</td>
+<td class="tdr">
+<a href="#CONSTELLATIONS">27</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Meteors: “Shooting Stars”
+</td>
+<td class="tdr">
+<a href="#METEORS_SHOOTING_STARS">28</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Meteorites
+</td>
+<td class="tdr">
+<a href="#METEORITES">29</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Comets
+</td>
+<td class="tdr">
+<a href="#COMETS">30</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Nebulae
+</td>
+<td class="tdr">
+<a href="#NEBULAE">32</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Milky Way
+</td>
+<td class="tdr">
+<a href="#THE_MILKY_WAY">33</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Number of Stars
+</td>
+<td class="tdr">
+<a href="#THE_NUMBER_OF_STARS">33</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Position of Our Solar System
+</td>
+<td class="tdr">
+<a href="#THE_POSITION_OF_OUR_SOLAR_SYSTEM">35</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Movement of Our Solar System
+</td>
+<td class="tdr">
+<a href="#THE_MOVEMENT_OF_OUR_SOLAR_SYSTEM">36</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Distances of the Stars
+</td>
+<td class="tdr">
+<a href="#DISTANCES_OF_THE_STARS">36</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Temperature of the Stars
+</td>
+<td class="tdr">
+<a href="#TEMPERATURE_OF_THE_STARS">37</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Fixed Stars
+</td>
+<td class="tdr">
+<a href="#FIXED_STARS">37</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Double Stars
+</td>
+<td class="tdr">
+<a href="#DOUBLE_STARS">38</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Colored Stars
+</td>
+<td class="tdr">
+<a href="#COLORED_STARS">38</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Variable Stars
+</td>
+<td class="tdr">
+<a href="#VARIABLE_STARS">39</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+<span class="pagenum" id="Page_4">[Pg 4]</span>Temporary Stars
+</td>
+<td class="tdr">
+<a href="#TEMPORARY_STARS">40</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Star Groups—Clusters
+</td>
+<td class="tdr">
+<a href="#STAR_GROUPS-CLUSTERS">40</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Eclipses
+</td>
+<td class="tdr">
+<a href="#ECLIPSES">41</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Telescopes
+</td>
+<td class="tdr">
+<a href="#TELESCOPES">43</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Spectroscope: Spectrum Analysis
+</td>
+<td class="tdr">
+<a href="#THE_SPECTROSCOPE_SPECTRUM_ANALYSIS">43</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Photography
+</td>
+<td class="tdr">
+<a href="#PHOTOGRAPHY">46</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Tides
+</td>
+<td class="tdr">
+<a href="#THE_TIDES">47</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Gravitation
+</td>
+<td class="tdr">
+<a href="#GRAVITATION">48</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Ether
+</td>
+<td class="tdr">
+<a href="#THE_ETHER">49</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Atomic Analogies
+</td>
+<td class="tdr">
+<a href="#ATOMIC_ANALOGIES">49</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Thunder and Lightning
+</td>
+<td class="tdr">
+<a href="#THUNDER_AND_LIGHTNING">50</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Fireballs
+</td>
+<td class="tdr">
+<a href="#FIREBALLS">50</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Atmospheric Electricity
+</td>
+<td class="tdr">
+<a href="#ATMOSPHERIC_ELECTRICITY">50</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Earth’s Magnetism
+</td>
+<td class="tdr">
+<a href="#THE_EARTHS_MAGNETISM">51</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Aurora Borealis
+</td>
+<td class="tdr">
+<a href="#THE_AURORA_BOREALIS">51</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Time: Measurement of
+</td>
+<td class="tdr">
+<a href="#TIME_MEASUREMENT_OF">52</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Space: Measurement of
+</td>
+<td class="tdr">
+<a href="#SPACE_MEASUREMENT_OF">52</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The International Day Line
+</td>
+<td class="tdr">
+<a href="#THE_INTERNATIONAL_DAY_LINE">54</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Calendars, etc.
+</td>
+<td class="tdr">
+<a href="#CALENDARS_ETC">54</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Curved Space
+</td>
+<td class="tdr">
+<a href="#CURVED_SPACE">55</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Temperature of Space
+</td>
+<td class="tdr">
+<a href="#THE_TEMPERATURE_OF_SPACE">55</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Light in Space
+</td>
+<td class="tdr">
+<a href="#LIGHT_IN_SPACE">55</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Life in Space
+</td>
+<td class="tdr">
+<a href="#LIFE_IN_SPACE">56</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+The Causes of an Ice Age
+</td>
+<td class="tdr">
+<a href="#THE_CAUSES_OF_AN_ICE_AGE">56</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Why Do Stars “Twinkle”?
+</td>
+<td class="tdr">
+<a href="#WHY_DO_STARS_TWINKLE">56</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Why Does the Moon Sometimes Appear Larger?
+</td>
+<td class="tdr">
+<a href="#WHY_DOES_THE_MOON_SOMETIMES_APPEAR">57</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+Are the Planets Inhabited?
+</td>
+<td class="tdr">
+<a href="#ARE_THE_PLANETS_INHABITED">57</a>
+</td>
+</tr>
+<tr>
+<td class="tdl">
+A Few Definitions
+</td>
+<td class="tdr">
+<a href="#A_FEW_DEFINITIONS">58</a>
+</td>
+</tr>
+</table>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_5">[Pg 5]</span></p>
+
+
+  <h2 class="nobreak" id="INTRODUCTORY">
+    INTRODUCTORY
+  </h2>
+</div>
+
+
+<p>Astronomy is one of the oldest of the sciences—as
+it is one of the most fascinating! The
+early Egyptians, Assyrians, Babylonians and
+Chaldeans were, as we know, great astronomers,
+and, considering that they were compelled to
+make their observations without the aid of telescopes,
+some of their conclusions are truly remarkable
+in their accuracy. Men must always
+have gazed at the stars, and wondered at their
+number and their beauty; yet it is only within
+the past three or four centuries that accurate
+ideas as to the nature, size and structure of our
+Universe have come into being. No subject is
+so calculated to impress upon man his own
+relative insignificance as astronomy—to show
+him that the speck of matter upon which he
+dwells is so small that it cannot even be seen,
+from a relatively short distance in space! How
+puny and absurdly trifling seem his bickerings
+and his disputes, his wars and his hates, his
+jealousies and his failures, when viewed from
+the standpoint of infinite time and infinite
+space; mere struggles upon an ant hill, which,
+a few million years from now, will be uninhabitable,
+while the sublime immensity of
+Nature will proceed as if nothing had happened!</p>
+
+<p>Yes, astronomy is a fascinating and romantic
+study, and the following little book is an attempt
+to summarize, very briefly, the most important
+findings of modern astronomical science
+<span class="pagenum" id="Page_6">[Pg 6]</span>upon this question. I have endeavored to make
+the subject as simple as possible, and to avoid
+all terms of a technical character, unless these
+are fully explained. It is my hope that the
+reader may be enabled to gain a fairly clear
+and accurate idea as to the nature and constitution
+of our Universe by a perusal of this
+little book.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_7">[Pg 7]</span></p>
+
+
+  <p class="ph1">
+    ASTRONOMY FOR BEGINNERS
+  </p>
+  <h2 class="nobreak" id="ASTROLOGY">
+    ASTROLOGY
+  </h2>
+</div>
+
+
+<p>Those who have not studied this subject will
+often ask the question: “What is the difference
+between Astronomy and Astrology?” It is
+merely this: Astronomy studies the heavenly
+bodies, and their movements, etc., by all available
+scientific means; while astrology, also
+utilizing this material, further asserts that the
+particular relative positions which the sun,
+moon, planets and other heavenly bodies occupy
+at the moment of birth <i>influence the individual</i>
+born at that moment, and continue to influence
+him all through life. In other words, astrology
+is undoubtedly an exact science in so far
+as its astronomical <i>data</i> are concerned; but its
+further inference, as applied to the living human
+being, is not; it depends upon historic
+beliefs and traditions which have been handed-down
+for centuries. So far as astronomers
+have been enabled to ascertain, there is not
+the slightest scientific basis for any belief in
+astrology; assuredly it is a curious and interesting
+occult study, but it must be understood
+to lie within that realm, rather than in that
+of exact astronomical science.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_8">[Pg 8]</span></p>
+
+
+  <h2 class="nobreak" id="THE_SOLAR_SYSTEM">
+    THE SOLAR SYSTEM
+  </h2>
+</div>
+
+
+<p>When we speak of the “solar system,” we
+mean our central Sun, and the various planets
+which revolve around it. The planets, beginning
+with the one nearest the Sun, and proceeding
+outwards into space, are: Mercury, Venus,
+The Earth, Mars, Jupiter, Saturn, Uranus,
+Neptune. Most of these planets have in turn,
+circling round them, smaller bodies of satellites;
+the Earth has but one—the Moon. Other
+planets have more than one. The planets vary
+greatly in size, as well as in their relative
+distances from the Sun. The following may
+help the reader to form a mental picture of
+their relative distances and sizes:</p>
+
+<p>Imagine a large open common; on it place
+a globe 2 feet in diameter, by way of representing
+the Sun; Mercury will then be represented
+by a mustard seed at a distance of 82
+feet; Venus by a pea at a distance of 142 feet;
+the Earth also by a pea, at a distance of 215
+feet; Mars will be a small pepper corn, at a distance
+of 327 feet; the Minor Planets by grains
+of sand at distances varying from 500 to 600
+feet; then a moderate sized orange ¼ of a
+mile distant from the central point will represent
+Jupiter; a small orange ⅖ths of a mile,
+Saturn; a full-sized cherry, ¾ths of a mile,
+Uranus; and lastly a plum, at 1¼ miles, Neptune,—the
+most distant planet yet known,—though
+some astronomers suspect there may
+exist another planet still further off, and hope
+<span class="pagenum" id="Page_9">[Pg 9]</span>one day to find it. (On the same scale, the
+<i>nearest</i> “fixed” star would be 7,500 miles distant).</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_SUN">
+    THE SUN
+  </h2>
+</div>
+
+
+<p>The Sun is the center of our solar (sun)
+system; it is the great giver of light and heat,
+without which life upon our planet would soon
+become extinct. It is an immense body, more
+than a million times the size of our earth. In
+fact, its <i>radius</i> is nearly twice the distance of
+the moon from the earth! The mass of the
+Sun is 332,000 times that of the earth. It gives
+600,000 times as much light as the full moon.
+The energy radiated per square yard from the
+Sun is equivalent to 140,000 horse power. The
+heat radiated by the sun would melt a layer
+of ice 4,000 feet thick every hour, all over its
+surface. Various estimates of the amount of
+heat upon the surface have been made, but
+these do not agree,—figures all the way from
+10,000° F. to 180,000° F. having been given.
+Certain it is that its internal heat is terrific,
+and there is every indication that this heat
+has been more or less constant for millions of
+years in the past. No purely physical theories
+of its heat are at all satisfactory. The ultimate
+nature and source of the sun’s heat are
+unknown—though various theories have been
+advanced by way of explanation. I have discussed
+this question at some length, however
+in my little book in the present series, “New
+Discoveries in Science,” to which the reader
+is referred. (“What Keeps the Sun Hot?”)</p>
+
+<p><span class="pagenum" id="Page_10">[Pg 10]</span></p>
+
+<p>The nature and constitution of the sun have,
+of course, been studied intensively for many
+years by astronomers. The apparent surface
+of the sun is called the “photosphere” (light
+surface). It is the part that gives forth most
+of the light and heat. Above the photosphere
+lies a sheet of gas, probably from 500 to 1,000
+miles thick, called the “reversing layer,” which
+is cooler than the photosphere. Outside the
+photosphere is another layer of gas, from 5,000
+to 10,000 miles deep, called the “chromosphere”
+(cooler sphere). The outermost portion of the
+Sun is the “corona” (crown). It is a halo of
+pearly light surrounding the sun, but it cannot
+be seen except during a total eclipse. It is of
+irregular form, and gradually fades out into
+the blackness of space at a distance of from
+1,000,000 to 3,000,000 miles. This must not be
+confounded with the so-called “prominences,”
+which are vast eruptions of flame, spurting
+out from the sun’s surface, and extending into
+space for enormous distances—perhaps half a
+million miles! These also travel with enormous
+velocity—five or six hundred miles per
+second. The earth would appear an insignificant
+speck of dust, in this vast, roaring furnace
+of flame!</p>
+
+<p>Of late years, the question of the so-called
+“sun spots” has aroused a great deal of interest,
+partly by reason of the fact that they
+apparently affect electrical and magnetic conditions
+upon the earth. These “spots” seem to reappear
+at stated intervals, and about every
+eleven years reach their maximum intensity,
+<span class="pagenum" id="Page_11">[Pg 11]</span>(The period of the revolution of the sun on its
+own axis has been estimated by their study.)</p>
+
+<p>Although the sun-spots were studied before
+the eighteenth century, it is only within the
+past few years that the significance of these
+enormous spots has become known. For long it
+was thought that they were merely the great
+volcanoes of the sun; centers of great heat,
+generated by the glowing, fiery gases of the
+sun. In 1908, however, Prof. Hale demonstrated
+that the sun-spots acted as attraction
+centers, which drew towards them the hydrogen
+of the solar atmosphere. “Subsequently, it was
+found that these spots are the seats of great
+cyclones, in which cool hydrogen gas is set
+whirling and is sucked down in the great
+mælstrom of the Sun, rushing into the center
+of the spot at the rate of 60 miles a second.
+Consequently the spots are the center of great
+solar disturbances, which are of an electromagnetic
+nature.” From this it was concluded
+(1) that the spots are cooler than the surrounding
+area; (2) they are centers of violent
+cyclones; and (3) they are magnetic fields of
+great intensity. The connection of sun-spots
+with our weather, and the relation of one to the
+other, have also been studied within the past
+few years.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="MERCURY">
+    MERCURY
+  </h2>
+</div>
+
+
+<p>This is the smallest of the planets in our
+solar system, being only about 3,000 miles in
+diameter. It revolves round the sun in almost
+exactly 88 days, at a distance of approximately
+36,000,000 miles, varying between 28½ million
+<span class="pagenum" id="Page_12">[Pg 12]</span>to 43½ million miles. Owing to its smallness,
+it is often difficult to see this planet, and a
+powerful telescope must be employed to study
+it effectually. It is thought that Mercury possesses
+mountains, but it is practically devoid
+of atmosphere. Dark, irregular spots have
+been observed upon the planet, and its surface
+is thought, by some astronomers, to resemble
+that of Mars, to a great extent. The
+solar heat on Mercury is about seven times
+that on us, owing to its proximity to the Sun.
+Schiaparelli, and others, have contended that
+the period of rotation of Mercury is exactly
+equal to its period of revolution round the Sun.
+If that be true, one side of the planet is always
+turned to the Sun, and the other side away
+from it. One side of the planet would thus be
+intensely hot, while the other side would be icy
+cold. Comparatively little is known concerning
+this small planet, though much study has been
+devoted to it.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="VENUS">
+    VENUS
+  </h2>
+</div>
+
+
+<p>This is one of the brightest and most beautiful
+“stars” in the sky, and has for long been
+the theme of poets. It is practically the same
+size as our earth, its diameter being approximately
+7,500 miles. It travels round the Sun
+in 224 days, at a mean distance of 67,000,000
+miles. It revolves on its own axis in about 23½
+hours, so that its days are nearly the same as
+ours. It is thought that Venus has a fairly
+dense atmosphere, and also water-vapor, which
+proves the existence of water upon its surface.
+Dense layers of cloud exist in the upper regions
+<span class="pagenum" id="Page_13">[Pg 13]</span>of its atmosphere, making direct observations
+of its surface very difficult. For this reason,
+comparatively little is known as to the conditions
+on the surface of Venus. Every eighth
+year Venus passes through a period of great
+brilliance, being then so bright as to cast a
+shadow, like the Moon. Venus must have a
+higher temperature than our earth; its sky is
+always overcast; thunder and lightning must be
+never-ending. Some controversy has existed
+as to the habitability of Venus; but the consensus
+of opinion is that life would be practically
+impossible upon its surface.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_EARTH">
+    THE EARTH
+  </h2>
+</div>
+
+
+<p>The earth on which we dwell was thought by
+the ancients to be the center of the entire Universe—the
+Sun, stars and the vast host of
+Heaven were thought to revolve around it. This
+was the so-called “geocentric” theory. It was
+later on displaced by the so-called “heliocentric”
+theory, when it was found that the Sun, and not
+the Earth, was the center of our system. It
+only remains to be said that our Earth is the
+third of the planets which revolve round the
+Sun—Mercury and Venus being nearer the Sun
+than we are, and the others still further removed
+in space. We are thus but one of a
+number of similar bodies moving through space,
+all revolving round the central Sun.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="MARS">
+    MARS
+  </h2>
+</div>
+
+
+<p>This now-famous planet is somewhat smaller
+than our earth, being about 5,000 miles in
+diameter. It travels round the Sun in 686 days,
+<span class="pagenum" id="Page_14">[Pg 14]</span>at a mean distance of 140,000,000 miles. The
+eccentricity of its orbit is considerable. Mars
+appears to us reddish in color, owing to the
+vast stretches of arid soil (desert) which exist
+upon its surface. Water exists, but it is
+relatively scarce; it is gradually drying-up, as
+it does in the case of all bodies of the kind—the
+water on our own earth is very gradually becoming
+less and less, as the centuries pass.</p>
+
+<p>Mars has been drawn particularly to the
+public’s attention, of late years, by reason of
+the dispute (still raging) as to its habitability,
+and the character of its so-called “canals”—the
+more or less regular markings, like long, dark
+lines which have been seen to exist upon its
+surface. Its surface has accordingly been
+studied minutely for many years, but it may be
+said that no unanimity of opinion exists as to
+its being an inhabited planet. Says Kæmpffert,
+in his “Astronomy,” (pp. 183-84):</p>
+
+<p>“The mapping of Mars is no recent matter,
+for even in 1659 a rough sketch of the surface
+of the planet was made by Huygens, in which
+the V-shaped markings at the equator, pointing
+to the north, can be identified as the <i>Syrtis
+Major</i>. This was followed by rough sketches
+from time to time down to 1840, when Maedler
+first began a systematic charting of the planet.
+His map was followed in 1864 by Kaiser’s, by
+Flammarion’s in 1876, and Greene’s in 1877.
+Drawings of various parts of the planet were
+made during these intervals, but were not
+combined into good charts.”</p>
+
+<p>“Observations made by Prof. Lowell and his
+staff at the Observatory, at Flagstaff, Arizona,
+<span class="pagenum" id="Page_15">[Pg 15]</span>have had a study of this planet especially in
+view.... The surface of Mars as seen in the
+telescope, is composed of two white polar caps,
+which wane with the approach of summer;
+orange areas, which are supposed by Lowell to
+be deserts, and blue-green areas, which change
+their hue to orange during the Martian autumn
+and winter, and resume their verdant tint in
+spring. The planet is covered with a network
+of fine lines, first discovered by Schiaparelli,
+in 1877; and called by him ‘canals’—a designation
+by which they are still known. These
+canals connect the polar caps with the temperate
+and equatorial zones. According to Prof.
+Lowell, they may be regarded as planetary irrigation
+ditches, which serve the purpose of
+leading the melting water of the poles to those
+desert regions which would still blossom, if
+properly watered. The canals disappear with
+the approach of winter, and creep down from
+the poles towards the equator in summer—a
+phenomenon which long puzzled astronomers,
+until Pickering ingeniously suggested that we
+see, not the canals themselves (for they are
+much too narrow) but the vegetation which
+fringes their banks—which withers as the cold
+of winter descends, and which flourishes with
+the melting of the snows.”</p>
+
+<p>It may be said that this theory of the canals
+on Mars is not universally accepted by astronomers,
+but is warmly disputed in some
+quarters. The <i>markings</i> are undoubted; but
+some astronomers are inclined to think they
+are due solely to vegetal growth, and are not
+the result of human hands. The controversy
+<span class="pagenum" id="Page_16">[Pg 16]</span>still continues. Meanwhile, two satellites of
+Mars were discovered in 1877.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="JUPITER">
+    JUPITER
+  </h2>
+</div>
+
+
+<p>Jupiter is the largest of all the planets, having
+a diameter of about 88,000 miles; it is only
+about 1,000 times smaller than the sun—that is,
+about 1,000 times larger than our earth. In
+volume, it is 1,300 times larger than our globe.
+Gravitation must be enormous on its surface.
+Its density is however relatively low—being
+only about one-quarter that of the earth. It is
+thought to be a world of water and more or less
+dense gas. It is constantly covered by a thick
+blanket of clouds and vapors, making direct
+observation very difficult—as we saw was the
+case with some other planets. Immense as this
+planet is in size, it revolves at a tremendous
+speed—approximately 10 hours. Owing to its
+immense bulk, it cools more slowly than a body
+such as our earth. Consequently it will take
+tens of millions of years for it to cool sufficiently
+to permit life to become manifest upon
+its surface. Yet it may at that time! In a
+sense, Jupiter may be said to be a planet of
+the future; when our earth is cold and dead,
+Jupiter may be teeming with animate existence.</p>
+
+<p>Jupiter has 8 satellites, and a number of dark
+bands cross its surface from east to west. A
+certain dark spot upon its surface has caused
+great interest among astronomers, who are unable
+to determine its exact nature. This planet
+revolves round the Sun in rather more than
+11¾ years, at a mean distance of 483,000,000
+miles.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_17">[Pg 17]</span></p>
+
+
+  <h2 class="nobreak" id="SATURN">
+    SATURN
+  </h2>
+</div>
+
+
+<p>Saturn revolves round the Sun in 29½ years,
+at a mean distance of 886,000,000 miles, in an
+orbit slightly eccentric. According to Barnard,
+its equatorial diameter is 76,470 miles, and its
+polar diameter 69,770, which figures imply a
+polar compression of 1/11. This planet is
+famous for the celebrated “ring” which surrounds
+it. As a matter-of-fact, when observed
+by means of high-powered telescopes, this
+famous “ring” is found to consist of a number
+of rings—three being clearly distinguishable.
+For long it was thought that these rings were
+vaporous; then that they were solid; but the
+present view is that they are composed of
+myriads of discrete particles of matter, so closely
+compacted together that to our remote eyes
+they appear as a solid mass. These rings are
+fairly broad, but relatively thin in diameter;
+they resemble a sort of huge disk. Perhaps
+100 miles would be the thickness of these rings.
+Their diameter, however, is tens of thousands
+of miles in breadth. Owing to these rings,
+Saturn is one of the most beautiful of all the
+planets, when viewed through a high-powered
+telescope.</p>
+
+<p>Saturn doubtless has certain features in common
+with Jupiter, as to its physical appearance.
+The general hue of the planet is yellowish-white;
+it probably has no atmosphere, or at
+most a very tenuous one. It is attended by ten
+satellites, the largest of which is known as
+Titan, thought to be about 2,700 miles in
+diameter.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_18">[Pg 18]</span></p>
+
+
+  <h2 class="nobreak" id="URANUS">
+    URANUS
+  </h2>
+</div>
+
+
+<p>This is the next to the last planet in our
+solar system. It is a large planet, having a
+diameter of about 31,000 miles. Uranus revolves
+round the Sun in rather more than 84
+years, at a mean distance of 1,781,000,000 miles.
+It is attended by four (or five) satellites. Belts
+and spots have been seen upon its surface, but
+relatively little is known concerning its
+physical conditions, owing to its great distance
+from us, and its relative smallness. This planet
+was discovered, as is well known, by Herschel,
+and was named after him, but its name was
+subsequently changed. (It is still mentioned as
+Herschel, in certain books upon Astrology.) It
+is probable that the temperature of Uranus is
+relatively low, owing to the small percentage
+of the sun’s rays which reach its surface. It
+has been calculated that its theoretical temperature
+is about 330° F.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="NEPTUNE">
+    NEPTUNE
+  </h2>
+</div>
+
+
+<p>The past century was remarkable for the discovery
+of this new planet: Neptune. How it
+was accomplished is a matter of great interest.
+In 1820, it was found that Uranus was not following
+its computed path. Adams, of Cambridge,
+and Leverrier, of Paris, each independently
+took up this question, and, assuming
+that this perturbation was due to the presence
+of a planet still more remote from the sun
+(which had been hinted at in 1830 by Bessel)
+they set to work to calculate its position in the
+<span class="pagenum" id="Page_19">[Pg 19]</span>heavens. They finished this at about the same
+time, arriving at practically the same conclusions.
+Adams’ results were first submitted to
+the Astronomer Royal, who set them aside without
+consideration until too late. Leverrier sent
+his conclusions to a German astronomer, Galle,
+who found the planet the first evening he
+looked for it, September 23, 1846.</p>
+
+<p>Neptune is the furthest known planet of our
+solar system; it is a very large body, having a
+diameter of about 37,000 miles. It revolves
+round the sun in an immense orbit which it
+takes 164 years to complete. Its mean distance
+from the Sun is nearly 2,800,000,000 miles—a
+majestic sweep through the heavens! Relatively
+little is known as to the physical conditions
+of Neptune, owing to its immense distance,
+and its relatively small size. At least
+one satellite is known to exist. The temperature
+on Neptune must be extremely low, owing
+to its distance from the sun, whose rays would
+be exceedingly feeble at that great distance.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_MINOR_PLANETS">
+    THE MINOR PLANETS
+  </h2>
+</div>
+
+
+<p>Between Mars and Jupiter, a number of small
+bodies are known to exist, which have sometimes
+been dignified by the name of “minor
+planets.” They have also been called “Planetoids”
+and “Asteroids.” Special names have
+been given these individual small bodies—Eros,
+Ceres, Pallas, Vesta, Juno, etc. Eros passes,
+upon occasions, very close to our earth; again
+passing beyond the orbit of Mars. Several hundreds
+of these smaller planets are now known
+to exist—as though they were the remnants of
+<span class="pagenum" id="Page_20">[Pg 20]</span>some shattered world. These bodies are very
+small: Ceres, <i>e.g.</i>, being about 250 miles in
+diameter; Pallas, 304 miles; Vesta, 211 miles;
+while a number of the others are thought to
+be from 5 to 15 miles in diameter.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="ARE_THERE_OTHER_PLANETS">
+    ARE THERE OTHER PLANETS?
+  </h2>
+</div>
+
+
+<p>Inasmuch as some of the planets known to
+us have only been discovered so lately (relatively)
+the question has naturally been asked:
+“Why may there not be <i>other</i> planets, beyond
+Neptune, still undiscovered?” It is a perfectly
+legitimate question, and no definite answer to
+this query can be given. It seems rather
+improbable that another planet will be discovered.
+However, it is a conceivable possibility,
+and M. Flammarion has stated that, in his estimation,
+such a planet probably exists—gravitating
+at a distance 48 times as great as the distance
+between the earth and the sun—that is
+to say, 7,500 million miles, in an immense orbit
+which it takes at least 330 years to accomplish.
+Proof as to the existence of such a planet has
+not, however, as yet been forthcoming.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_MOON">
+    THE MOON
+  </h2>
+</div>
+
+
+<p>The Moon is the Earth’s only satellite, and
+by far the nearest body in space to our Earth.
+Many astronomers are inclined to think that
+the Moon at one time formed a part of the
+Earth, but was wrenched away from it, leaving
+a huge cavity, which is now occupied by the
+Pacific Ocean. The Moon is a cold body, emitting
+no light or heat of its own; all the light
+<span class="pagenum" id="Page_21">[Pg 21]</span>which it seems to shed is entirely <i>reflected</i>
+light—reflecting the sun’s rays, much as a
+mirror might reflect them; hence its beautiful
+silver color.</p>
+
+<p>In round numbers, the Moon is approximately
+240,000 miles distant from us in space—the distance
+varying from 221,600 miles to 252,970
+miles—causing a corresponding variation in its
+apparent diameter and parallax.&#x2060;<a id="FNanchor_A_1" href="#Footnote_A_1" class="fnanchor">[A]</a> The circumference
+of the Moon’s orbit is a little more than
+a million-and-a-half miles, and it travels
+through space with the velocity of 2,288.6 miles
+per hour, or 3,357 feet per second.</p>
+
+<div class="footnote"><p><a id="Footnote_A_1" href="#FNanchor_A_1" class="label">[A]</a> See <a href="#Page_58">page 58</a> for a definition of this term.</p></div>
+
+<p>Our satellite always keeps the same face
+turned towards the Earth, so that we only see
+one side of it; the other side is forever hidden
+from the sight of man. However, the axis of
+the Moon tilts, in relation to the earth, and
+permits us to glimpse a little more of the surface
+both north and south, so that about five-eighths
+of the surface has actually been observed.</p>
+
+<p>The surface of the Moon has been subjected
+to intensive study, and its “geography” is now
+as well known as that of our own earth. Vast
+“seas” (i. e.) sea bottoms, mountain ranges,
+solitary mountain peaks, enormous craters, are
+readily observed, and modern telescopes have
+now brought the moon so close to us that it
+has been said that any body as high as the
+Woolworth Building, in New York, would cast
+a shadow which could be observed and noted.</p>
+
+<p><span class="pagenum" id="Page_22">[Pg 22]</span></p>
+
+<p>The fact that the same face of the Moon is
+always seen by man does not mean that this
+body remains stationary; it revolves on its own
+axis, from west to east, but this revolution occupies
+exactly one siderial month. The result
+is that the days and nights on the Moon, are
+many times the length of our days and nights.
+The surface exposed to the sun’s rays must get
+extremely hot, and, when deprived of these
+rays, extremely cold. It has been estimated
+that the mean temperature of the moon’s surface
+must approximate 200° F., during the
+“day” time, and approach the intense cold of
+inter-stellar space during the “night” (perhaps
+-250° C.). This would render life or vegetation
+of any kind very unlikely. However, Professor
+Pickering has lately asserted that vegetation
+<i>does</i> apparently spring into being with extreme
+rapidity during the moon’s day time—evidently
+remaining latent during the intense
+cold of the “night.” (Some interesting material
+on this topic may be found in Shipley’s
+“Is the Moon a Dead World?” No. 557 of the
+present series.)</p>
+
+<p>The volume of the Moon is about one-fiftieth
+that of the earth, but its mass is only about
+one-eightieth that of our planet. The Moon is
+practically devoid of atmosphere, which is another
+reason why it cannot support “life,” in
+our sense of the word. Two theories have been
+advanced as to the absence of the moon’s atmosphere:
+(1) that it gradually combined, chemically,
+with the materials on its surface; and
+<span class="pagenum" id="Page_23">[Pg 23]</span>(2) that it gradually escaped into space, because
+of the low gravitational pull of the moon.
+There is no water on our satellite, which means
+that there is no ice and no snow. The moon
+being so much smaller than our earth, the pull
+of gravity is of course much less also.</p>
+
+<p>Yet it is well known that the tides, on the
+earth, are greatly influenced by the moon.
+Every atom composing our satellite must exert
+some subtle pull upon every atom of our oceans,
+in order thus to affect them. What is the nature
+of this attraction? Here we encounter the
+mystery of gravitation! This question must
+accordingly be postponed until we come to our
+discussion of that subject.</p>
+
+<p>One of the most remarkable and distinguishing
+characteristics of the moon consists in the
+so-called “lunar craters,” which appear to be
+immense, extinct volcanoes. More than 30,000
+of these have now been mapped, varying in size
+from small hills to immense basins 50, 60,
+100 miles in diameter. Ptolemy is 115 miles
+across, while Theophilus is 64 miles in diameter
+and 19,000 feet deep. The curious thing about
+these lunar craters is that they are unlike the
+hilly volcanoes known to us on our earth. They
+are rather huge circular pits, often square miles
+in extent, surrounded by a circular wall, and
+almost invariably having a single mountainous
+cone in the center.</p>
+
+<p>Various theories have been advanced by way
+of explanation of these craters. The most important
+of these are (1) that they represent extinct
+volcanoes; (2) that they indicate spots
+where masses of matter have dashed into the
+<span class="pagenum" id="Page_24">[Pg 24]</span>moon, from surrounding space; and (3) that
+they represent the surface of the moon, when
+it was a hot, seething mass—their resemblance
+to the “bubbles” formed at the surface of boiling
+glue, mud, etc., being pointed to as analogous.
+Unanimity of view does not exist even
+yet as to their origin.</p>
+
+<p>The ever-changing “phases” of the moon have
+been observed by generations of lovers. Thus,
+the new moon, full moon, etc., are commonplace
+sights. These apparent changes are, of course,
+due entirely to the relative position of the sun
+at the time. If the sun illumines the whole
+face of the moon, as viewed from our earth, we
+have full moon; if only a small portion of it,
+we see the first quarter, etc. The whole disk
+of the moon may always be seen, however, by
+careful observation. It is hardly necessary to
+say that the so-called “Man in the Moon” is a
+mind’s eye picture, created by the configuration
+of the various mountains, seas, etc., upon
+its surface.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_ORIGIN_OF_THE_SOLAR_SYSTEM">
+    THE ORIGIN OF THE SOLAR SYSTEM
+  </h2>
+</div>
+
+
+<p>Men in every age have speculated as to the
+constitution and origin of our world, and of
+the Universe in general. The first really detailed
+and scientific attempt was made, however,
+little more than a hundred years ago by
+Laplace—and subsequently known as the Laplacian
+hypothesis (1796).</p>
+
+<p>Concurrent with the establishment of new
+facts, there was a tendency, throughout the past
+century, to find some philosophic interpretation
+of the Universe and its structure; to ascertain,
+<span class="pagenum" id="Page_25">[Pg 25]</span>if possible, the “beginnings of things,” and explain
+them in some satisfactory manner. This
+has been considered as epoch-making in astronomical
+research as Darwin’s great theory of
+the Origin of Species was in biology. The history
+of the two theories has been similar also.
+Both have served a useful purpose; have helped
+to direct scientific thought for years; and both
+are now largely outgrown. Both were, however,
+of great value and of daring originality.</p>
+
+<p>Laplace assumed the primal existence of a
+glowing ball of gas rapidly revolving about an
+imaginary axis running through its center of
+gravity. During the process of cooling, this
+mass would contract, and a disk of gas would
+be thrown off in this manner; and hence a
+number of gaseous rings be formed, which
+would ultimately cool down and assume a
+spherical form. Laplace conceived that this
+process might be interfered with by internal
+accident and by comets from without.</p>
+
+<p>The first modifications of the theory were
+suggested by Sir Norman Lockyer, who proposed
+what is known as the meteoritic hypothesis
+in its place. The central idea of the
+theory was that—“All self-luminous bodies in
+celestial space are composed either of swarms
+of meteorites or of masses of meteoric vapor
+produced by heat.” The theory was based on
+spectroscopic analysis. It said that the original
+nebulæ were composed, not of gases, but of
+meteoric material and cosmic dust. This theory
+was never fully accepted in place of that of
+Laplace, however; but it paved the way for a
+more recent theory, which may be said to be
+<span class="pagenum" id="Page_26">[Pg 26]</span>satisfactory and more or less inclusive. This
+is known as <i>the planetesimal hypothesis</i>, and
+was advanced within the past few years by F. R.
+Moulton and T. C. Chamberlin, of the University
+of Chicago. At the present time, it may
+be said to be the accepted theory, so far as any
+such theories are accepted, since it accords with
+all the facts in a remarkable manner, and has
+been experimentally demonstrated. In outline,
+the theory is as follows.</p>
+
+<p>If examination of the nebulæ in the sky be
+made, out of 120,000 of them, nearly every one
+of them is found to be in the spiral form. So
+common and universal is this, indeed, that it
+was concluded that this must represent “some
+prevalent process in celestial dynamics.” This
+process is, according to Chamberlin, the actual
+formation of a solar system. As this spiral
+revolves, it accretes to itself various smaller
+bodies, with their gases, atmospheres, etc., and
+these become consolidated with the original
+body. As time went on, this spiral gradually
+tended to decrease its speed, but at the same
+time, continued to accrete bodies which came
+into contact with it in its flight through space.
+Thus, we have to imagine our world, not as
+an expanded molten mass which has continuously
+cooled and contracted, but, on the contrary,
+as a small lump of cold and solid fragments
+that, moving about in accordance with
+its attractions, continuously fed upon its surrounding
+assemblage of “smaller fry,” and thus
+grew to its present size. About the young
+earth so engaged it is possible to read, on the
+basis of the hypothesis, something of its early
+history.</p>
+
+<p><span class="pagenum" id="Page_27">[Pg 27]</span></p>
+
+<p>Thus we see that the old theory of Laplace
+has been reversed; and that, instead of a great
+central mass of moving, white-hot gas, we have
+a number of smaller bodies, all busily engaged
+in building up themselves, at the expense of the
+surrounding masses of still smaller matter—much
+as a crystal accretes to itself minute
+specks of crystalline matter from the solution
+in which it is immersed. This is the newest
+of the cosmological theories. According to it,
+all the planets might have been formed at the
+same time. This view of the formation of the
+universe opens up still wider problems, which
+are now the subject of keen debate.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="CONSTELLATIONS">
+    CONSTELLATIONS
+  </h2>
+</div>
+
+
+<p>The ancients, when studying the heavens,
+saw all kinds of imaginary animals in the various
+star-groups, and named them accordingly.
+A constellation is really a group of stars, which
+seems to constitute a sort of system of its own.
+Thus, we find reference to the Great Bear, the
+Little Bear, the Bull, etc. It is difficult for the
+uninitiated to see the resemblances which the
+ancients did, in these various star-groups, and
+astronomical science has re-named them, as
+well as adding a large number of new constellations
+to those already known.</p>
+
+<p>Stars of the first six magnitudes (roughly)
+are visible to the unaided eye; those of lesser
+magnitude must be detected by the aid of telescopes.
+About 5,000 are thus visible; the number
+is increased according to the magnifying
+power of the telescope used, and it is estimated
+that there are more than 100,000,000 within
+<span class="pagenum" id="Page_28">[Pg 28]</span>the range of visual and photographic instruments!</p>
+
+<p>The names of a few of the best known constellations
+are as follows: Ursa Major (The
+Great Bear); Cassiopeia; Hercules; Scorpio
+(the Scorpion); Corona Borealis (The Northern
+Crown); Boötes (The Hunter); Leo (the
+Lion); Andromeda; Perseus; Auriga (The
+Charioteer); Taurus (the Bull); Orion; Canis
+Major (The Great Dog); Canis Minor (The
+Smaller Dog); Gemini (the Twins), etc.</p>
+
+<p>In these various constellations, certain noted
+stars are to be found. Thus, in Gemini, its two
+principal stars are Castor and Pollux. In Canis
+Major is Sirius. In Orion may be found Aldebaran
+and Betelgeuse. The Pleiades and Hyades
+groups are in Taurus. In Perseus is Algol. In
+Lyra is the first-magnitude star Vega. And
+so on.</p>
+
+<p>The “Big Dipper,” so-called, is part of the
+Constellation Ursa Major; and it is almost universally
+known that the Pole Star (Polaris)
+may readily be found by its means. The constellations
+must be traced and learned, one by
+one; but this the student must accomplish for
+himself!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="METEORS_SHOOTING_STARS">
+    METEORS: “SHOOTING STARS”
+  </h2>
+</div>
+
+
+<p>What are popularly known as “shooting
+stars” are not stars at all; they are really
+meteors which appear at altitudes of from 60
+to 100 miles, as a rule, from the earth, and
+move over paths of 40 or 50 miles at a rate of
+from 10 to 50 miles per second.</p>
+
+<p><span class="pagenum" id="Page_29">[Pg 29]</span></p>
+
+<p>The light given out by meteors is due to their
+being heated by friction with the atmosphere.
+Falling from space, they become attracted by
+the earth’s gravitation, and fall towards it.
+Here they encounter the earth’s atmosphere,
+and their rapid passage through it creates terrific
+heat, which tends to consume them before
+they reach the face of the earth, turning them
+into gases, or causing them to fall gently as
+dust. This sudden flash is the “shooting star”
+in question.</p>
+
+<p>The number of such meteors is very great.
+It has been computed that between ten and
+twenty million strike the earth’s atmosphere
+daily. Occasionally, a large number of meteors
+fall together; and then we have a “meteoric
+shower.”</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="METEORITES">
+    METEORITES
+  </h2>
+</div>
+
+
+<p>Occasionally, however, some of these bodies
+<i>do</i> reach our earth, despite the friction and
+opposition of the earth’s atmosphere. Such
+bodies are called meteorites, siderites, or aerolites.
+Only a few of these are seen to strike
+the earth yearly, and it is a remarkable fact
+that, so far as we have any record, not one
+of them has ever struck a town or killed an
+individual. The outside of the meteorite during
+its passage through the air is subject to
+intense and sudden heating, and the rapid expansion
+of its surface-layers often breaks it into
+many fragments. The surface is fused and,
+on striking, cools rapidly. The result is that
+it has a black, glossy structure, usually with
+<span class="pagenum" id="Page_30">[Pg 30]</span>many small pits where the less refractive material
+has been melted out. Such meteorites
+may be seen in most large museums.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="COMETS">
+    COMETS
+  </h2>
+</div>
+
+
+<p>During the past century, many of these
+“tramps of the solar system” have been discovered
+and their orbits computed. The “head”
+may range from ten thousand to a million
+miles, or more, while its “tail” may stream
+across the heavens for millions of miles. These
+comets’ tails always point away from the sun;
+and for long the reason for this was not known.
+It is now believed that this is due to light-pressure;
+the energy of the sun’s rays press
+this delicate matter outwards into space. (This
+theory has been elaborated at considerable
+length by the Swedish astronomer and chemist,
+Arrhenius.)</p>
+
+<p>Many readers of this little book will remember
+the excitement caused by Halley’s comet,
+which came relatively close to the earth in
+1910, so that many persons thought there would
+be a collision, and were terrified accordingly!
+As a matter of fact, the tails of comets are
+usually of almost inconceivable tenuosity.
+Halley first observed this comet, computed its
+orbit and predicted the date of its return.</p>
+
+<p>Some comets have tails: others do not. Not
+much is known concerning the origin and destination
+of comets; where they originated, or
+how. They travel at tremendous speed over
+many millions of miles of space, returning after
+a few years, or after a lapse of several centuries.
+<span class="pagenum" id="Page_31">[Pg 31]</span>They are very striking looking, even
+when observed by the naked eye. A number
+of comets have been noted. The following are
+a few of the more remarkable comets which
+were observed during the past century:</p>
+
+<p>The Comet of 1811. This was visible for
+nearly a year and a half, and was carefully
+studied by William Herschel. Its tail was said
+to be nearly a hundred million miles long, and
+fifteen million miles broad.</p>
+
+<p>Encke’s Comet (1819). This comet is of
+extreme interest because of its change of volume.
+Moulton says: “On October 28, 1828, it
+was 135,000,000 miles from the sun, and had
+a diameter of 312,000 miles. On December 24,
+its distance was 50,000,000 miles and its diameter
+was 14,000 miles; while at its perihelion
+passage of December 17, 1838, at a distance of
+32,000,000 miles, its diameter was only 3,000
+miles.”</p>
+
+<p>Beila’s Comet (1826). This comet has a
+most interesting history. In 1846 it was again
+seen; and a month later it had divided into
+two parts. They traveled along parallel orbits,
+some 160,000 miles apart. In 1852, they were
+seen to be 1,500,000 miles apart. Since then
+they have never been seen. They have, apparently,
+vanished from the face of creation!</p>
+
+<p>Donati’s Comet (1858). This comet was visible
+for more than nine months. Its tail was
+estimated as 54,000,000 miles long. Its period
+of revolution was more than 2,000 years.</p>
+
+<p>The Great Comets of 1880 and 1882. The
+latter of these passed through some hundreds
+<span class="pagenum" id="Page_32">[Pg 32]</span>of thousands of miles of the sun’s corona. Its
+orbit was not appreciably changed, but, after
+emerging, it was seen to possess at least five
+nuclei—showing the effect upon the comet of
+the disruptive forces through which it had
+passed.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="NEBULAE">
+    NEBULAE
+  </h2>
+</div>
+
+
+<p>These are of especial interest, for the reason
+that they have played so large a part in forming
+cosmic theories—the Laplacian, the Planetestimal,
+etc. Nebulæ are of various kinds—“Annular
+Nebulæ,” resembling a flat, oval, solid
+ring, having a dark hole in the center. Then
+there are “Elliptic Nebulæ,” of varying degrees
+of eccentricity; the Great Nebula in Andromeda
+being a good example. (Numbers of isolated
+stars may be found within its limits.) “Spiral
+Nebulæ” are, perhaps, the best known of all,
+and their name accurately describes their appearance.
+There are also the so-called “Planetary
+Nebulæ,” as well as Nebulous Stars, Irregular
+Nebulæ, etc. Of late years, much interest
+has been centered upon the so-called
+“Dark Nebulæ.” Herschel had long before described
+various “holes in the heavens,” wherein
+no stars could be discerned. It is now believed
+that such spots do not represent “holes,”
+as much as dark masses of matter, which seem
+to blot out the bright stars behind them. The
+interested reader may refer to Hale’s “The
+Depths of the Universe” for additional information
+upon this topic, which is relatively new
+to astronomy. It is also interesting to note
+that the spectra of Nebulæ contain the bright
+<span class="pagenum" id="Page_33">[Pg 33]</span>lines in the green of a substance called “nebulium,”
+because it is not found except in
+nebulæ.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_MILKY_WAY">
+    THE MILKY WAY
+  </h2>
+</div>
+
+
+<p>This is, in a sense, one vast nebula running
+right round the heavens in the form of a belt,
+or ring; its familiar resemblance to spilt milk
+being the origin of its popular name. To the
+naked eye, it appears merely a hazy band of
+light, but the telescope shows that it is made
+up of an enormous number of stars, millions
+of miles apart, but which can only be distinguished
+from one another by telescopic aid.
+It constitutes the so-called “Galaxy.” It seems
+to be spread out in the form of a vast disk,
+whose diameter is many times its thickness.
+Our solar system appears to be near the center
+of this vast system, and, as we penetrate
+further and further into space, it becomes
+apparent that fewer and fewer stars, and fewer
+and fewer nebulæ, seem to exist. Hence
+the limitation of the material Universe. The
+Milky Way is made up of thousands of millions
+of suns; yet their enormous distances make
+them appear to constitute one vast, luminous
+belt encircling our globe!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_NUMBER_OF_STARS">
+    THE NUMBER OF STARS
+  </h2>
+</div>
+
+
+<p>When the heavens are viewed with the naked
+eye, a few hundred stars may perhaps be seen—some
+bright, some faint. Viewed through opera
+glasses, many more stars may been seen; while
+their number is again greatly increased by the
+<span class="pagenum" id="Page_34">[Pg 34]</span>use of a telescope. The larger and more powerful
+the telescope employed, the greater the
+number of stars thus discovered in the depths
+of space. The interesting question thus arises:
+What is the total number of stars in the entire
+firmament? Can they be estimated? And if
+so, what would their approximate number be?</p>
+
+<p>What we call “stars” are, of course, in practically
+all cases <i>suns</i>—often vastly larger and
+hotter than our own. These stars differ from
+one another in order of brilliance; some are
+brighter than others. They are accordingly
+classified according to their order of brilliance,
+and known as stars of the “First Magnitude,”
+of the “Second Magnitude,” etc., up to about
+the Seventeenth Magnitude. Any star of a
+given magnitude is, roughly, about two-and-a-half
+times as brilliant as one of the next lower
+order, and this variation holds throughout—each
+magnitude being that much greater in
+brilliance.</p>
+
+<p>The “magnitude” of the stars varies according
+to their light-giving power, and also their
+distance from us. One of the methods adapted
+to measure the magnitude is to compare its
+brightness with an artificial star, gradually
+cutting-off its light by means of neutral, tinted
+glass until the two are equal. The color of
+the star must be taken into account, in such
+measurements, the eye being more sensitive to
+some colors than to others.</p>
+
+<p>Now, it is an interesting and significant fact
+that the number of the stars decreases as their
+magnitude decreases; that is to say, the greatest
+number of stars are found of the first magnitude;
+<span class="pagenum" id="Page_35">[Pg 35]</span>a lesser number of the second; still
+less of the third, and so on (broadly speaking).
+After reaching the ninth magnitude, the number
+very rapidly diminishes. It has been calculated
+that there are about 120,000,000 stars
+in the first 16 or 17 magnitudes. If the proportion
+were maintained throughout, however,
+there would be more than ten times that number.
+Some authorities have asserted that there
+are, roughly, half a billion stars of varying
+magnitudes in the heavens.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_POSITION_OF_OUR_SOLAR_SYSTEM">
+    THE POSITION OF OUR SOLAR SYSTEM
+  </h2>
+</div>
+
+
+<p>It has been maintained that our solar system
+is at, or very near, the center of the whole
+Universe. Certain it is that the further we
+proceed into space, the less the number of
+stars encountered, which has given rise to the
+suspicion that their number is actually <i>limited</i>,
+and that the whole Universe consists of a sort
+of sphere, in which is enclosed all the stars
+that exist, and that, beyond this sphere, no
+stars whatever remain. No matter exists beyond
+this point! Such a view fits in rather
+well with Einstein’s conception of “curved
+space,” and a finite universe of infinite proportions!
+Of course, it is conceivable that,
+outside this vast system, another similar system
+may exist, and another and still another;
+but of such systems we know nothing, and it
+seems improbable that proof of their existence
+could ever be obtained by man. So far as we
+can tell, the universe is <i>One</i>, and the matter
+and energy of that one are limited.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_36">[Pg 36]</span></p>
+
+
+  <h2 class="nobreak" id="THE_MOVEMENT_OF_OUR_SOLAR_SYSTEM">
+    THE MOVEMENT OF OUR SOLAR SYSTEM
+  </h2>
+</div>
+
+
+<p>It has been shown that our whole solar
+system is sweeping through space at the speed
+of about ten miles a second towards the stars
+in the constellation Hercules, and particularly
+towards Vega, one of its suns. However, Vega
+is likewise moving through space, so that by
+the time our sun reaches the spot now occupied
+by Vega (half a million years or so) Vega
+will no longer occupy that position, and no
+“collision” will take place in consequence! We
+shall not, in fact, pass very near that star.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="DISTANCES_OF_THE_STARS">
+    DISTANCES OF THE STARS
+  </h2>
+</div>
+
+
+<p>Astronomical distances are so vast that they
+can only be measured in the mind relatively.
+The distances between the planets in our own
+solar system seem big enough; yet they shrink
+into insignificance when compared to the distances
+which separate our whole solar system
+from even the nearest of the stars. <i>Alpha
+Centauri</i> is the nearest star, and it is separated
+from us by a distance 276,000 times as great
+as that which separates us from our sun. It
+is approximately 25 billion miles away. Traveling
+with the speed of an express train flung
+into space, at 40 miles an hour, towards the
+nearest star, without any stoppage or any slowing down,
+we should not arrive at our destination
+until after an interrupted flight of 75
+million years. Yet this is our nearest neighbour!
+Only a <i>very few</i> of the stars are within
+400,000,000,000,000 miles of the sun. The great
+<span class="pagenum" id="Page_37">[Pg 37]</span>majority of them are many times this distance
+from us.</p>
+
+<p>So vast are these distances that some simple
+means of expressing them on paper was
+sought. A “light Year” was finally decided
+upon as the <i>unit</i> of measurement—that is, the
+distance which light would travel in one year,
+speeding at the rate of 186,000 miles a second.
+It has been estimated that many stars are one,
+two, three and perhaps five hundred thousand
+light-years distant from us in space. The interested
+reader may figure-out the number of
+miles this represents for himself!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="TEMPERATURE_OF_THE_STARS">
+    TEMPERATURE OF THE STARS
+  </h2>
+</div>
+
+
+<p>Measurements which have been undertaken
+prove that the surface temperature of our Sun
+is between 5,000°C. and 7,000°C. It is thought
+that many stars are considerably hotter than
+this. We can form no adequate conception of
+such intense heat; all matter would be vaporized;
+yet, under the enormous pressures which
+must prevail, these vapors would in turn be
+converted into thick, semi-fluid substances—especially
+in the interior.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="FIXED_STARS">
+    FIXED STARS
+  </h2>
+</div>
+
+
+<p>The so-called “fixed” stars are those which
+do not appear to change their positions in the
+heavens for long periods of time together.
+There are, of course, no “fixed” stars at all
+since every celestial body is moving with
+greater or lesser rapidity through space; but
+these stars are so far distant from us that
+<span class="pagenum" id="Page_38">[Pg 38]</span>such movements are inappreciable, even after
+long periods of time, and in spite of the most
+careful observations. In comparison with the
+more rapidly moving heavenly bodies, they do
+not appear to “move,” and have been denominated
+“fixed stars” in consequence.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="DOUBLE_STARS">
+    DOUBLE STARS
+  </h2>
+</div>
+
+
+<p>A large number of stars appear single, when
+viewed by the naked eye, but when seen
+through a powerful telescope, are seen to be,
+in reality, two stars which revolve round one
+another. Many thousands of such double stars
+are now known to exist; indeed, apparently
+single stars have been found, upon closer
+examination, to be composed of a group of
+four or five or more stars—so that the name
+“multiple stars” has been given to such groups.
+They are near one another in the astronomical
+use of that word—though they may actually
+be hundreds of thousands, or millions of miles
+apart. Many of these double stars seem to be
+quite separate from one another. Others appear
+to have some physical connection. Those
+which are known to form systems are known
+as <i>binaries</i>.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="COLORED_STARS">
+    COLORED STARS
+  </h2>
+</div>
+
+
+<p>Many of the double stars exhibit curious and
+beautiful phenomena of complementary colors.
+In such cases, the larger star is usually more
+or less reddish or orange, and the smaller one
+bluish-green or greenish-blue. Many of the
+double stars, on the contrary, are of the same
+color. There are white, red, blue, orange,
+<span class="pagenum" id="Page_39">[Pg 39]</span>green and yellow stars. The planets also vary
+greatly in color—Venus, e.g., being white, Mars
+reddish, etc. Inasmuch as the planets only
+reflect light, however, this is due to quite different
+causes; the other colored stars are self-luminous
+suns which emit light of their own.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="VARIABLE_STARS">
+    VARIABLE STARS
+  </h2>
+</div>
+
+
+<p>In addition to variations in the color of
+stars, they also vary greatly in brilliance, and
+certain stars are much brighter at times than
+at others. In some cases these changes in
+brilliance are regular; in others, irregular.
+“Omicron,” for example, which, Bayer recorded
+in his Atlas in 1603, is a regular variable;
+its period of change is 331 days, 8 hours; in
+other words, it reaches its greatest brightness
+about 12 times in 11 years, when it sometimes
+attains the brilliancy of a star of the 2nd magnitude,
+at which brilliancy it remains stationary
+for about a fortnight. It then diminishes
+during about three months, until it sinks down
+to a star of magnitude 9½, or even becomes
+totally invisible. It remains in this condition
+for about 5 months, and then gradually recovers—during
+the next following 3 months—its
+maximum brilliancy. In other words, its
+brilliancy is absolutely periodic. Other variables
+are by no means regular, however, but
+“come and go” at different intervals.</p>
+
+<p>Various theories have been advanced by
+way of explanation—one of the simplest being
+that such stars are in reality double, one being
+luminous and the other not; and that, during
+their revolutions, the non-luminous star
+<span class="pagenum" id="Page_40">[Pg 40]</span>partially or totally eclipses the bright one, at
+stated intervals. The whole subject, however,
+is difficult, and much yet remains to be
+learned concerning these variable stars.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="TEMPORARY_STARS">
+    TEMPORARY STARS
+  </h2>
+</div>
+
+
+<p>From time to time, stars have suddenly appeared
+in the heavens, where no star existed
+before! Such stars have usually become increasingly
+brilliant for a short period of time,
+and then as suddenly died away again, leaving
+no trace of their existence behind them. These
+“new stars” for long puzzled astronomers.
+The theory often advanced to explain them is
+that some distant star has “exploded,” and the
+increasing brilliance which we see is the result.
+If such were the case, its sudden dimming-down
+and disappearance would be quite
+intelligible—as would be its sudden appearance.
+A large number of such stars have now
+been recorded, and their existence is no longer
+in doubt. In some cases, they have remained
+visible for weeks or months before
+their final disappearance.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="STAR_GROUPS-CLUSTERS">
+    STAR GROUPS—CLUSTERS
+  </h2>
+</div>
+
+
+<p>Here and there throughout the sky are places
+where the brighter stars seem to be clustered.
+These families of stars are of such magnificent
+proportions as to stagger the imagination.
+Among the best known are the Pleiades, the
+Hyades, Coma Berenices and Orion. Although
+they appear to us very close together, they
+are not really so, being usually several hundreds
+of thousands of miles apart. Many of
+<span class="pagenum" id="Page_41">[Pg 41]</span>these star-groups are irregular; but numbers
+of them constitute clusters, which are of various
+sizes and shapes. Perhaps the most interesting
+are the so-called “globular clusters,” because
+they present the appearance of stars
+having been massed together as globes. Some
+of them contain five or six thousand stars.
+Although they appear to us so close together,
+it has been calculated that, in a cluster containing
+5,000 stars the average distance of the
+stars from one another would be 30,000 times
+the distance of the sun from the earth! The
+vast distances of space considered in astronomy
+may perhaps be realized by this fact—when
+it is considered that such a cluster appears
+to us as a single star, only capable of
+being separated into its component parts by
+means of high-powered telescopes!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="ECLIPSES">
+    ECLIPSES
+  </h2>
+</div>
+
+
+<p>The total eclipse of the Sun, January 24,
+1925, brought the subject of eclipses to the public
+attention as never before, and many thousands
+of persons watched that beautiful and
+impressive sight through smoked glasses or
+strips of film.</p>
+
+<p>When we speak of eclipses, we usually mean
+an eclipse of either the Sun or the Moon.
+How are such eclipses caused?</p>
+
+<p>A total or partial eclipse of the sun is caused
+by the moon passing between the earth and
+the sun, the three celestial bodies forming, as
+it were, a straight line. The sun is then shut-off
+from the vision of the inhabitants of our
+globe over a certain, limited area of its surface.
+<span class="pagenum" id="Page_42">[Pg 42]</span>The shadow cast by the moon falls
+across the earth.</p>
+
+<p>But how is the moon eclipsed? Certainly
+the sun does not pass between the moon and
+the earth, on such occasions! What causes the
+moon to be eclipsed?</p>
+
+<p>The answer is as follows: Inasmuch as both
+the earth and the moon are illuminated by the
+sun, they both cast long shadows into space,
+as any solid body does, when held in front of
+a strong light. The earth’s shadow trails away
+for thousands of miles into space. Into this
+shadow the moon enters, and when it does so,
+it becomes eclipsed—totally or partially, as the
+case may be. Total eclipses are instances when
+the whole surface of the celestial body is apparently
+covered; partial eclipses are those in
+which only a portion of the body is dark—the
+remainder being still visible.</p>
+
+<p>In addition to eclipses, two other astronomical
+phenomena of interest should here be mentioned:
+<i>Transits</i>, and <i>Occultations</i>. By “transit”
+is meant the passage of some other heavenly
+body between ourselves and the sun. Thus,
+Mercury and Venus, both lying nearer the sun
+than the earth, occasionally pass in front of
+it. We then have a transit of Venus, or a
+transit of Mercury, as the case may be.</p>
+
+<p>By “Occultation” is meant the hiding of one
+heavenly body by another—as when the moon
+hides some other planet or star, or one planet
+hides another planet or star. The three bodies
+are then “in line” as before. Of course, all
+eclipses represent instances of Occultation.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_43">[Pg 43]</span></p>
+
+
+  <h2 class="nobreak" id="TELESCOPES">
+    TELESCOPES
+  </h2>
+</div>
+
+
+<p>Telescopes are of relatively recent origin;
+the ancients were forced to make their observations
+without them, which makes some of
+their conclusions all the more remarkable.
+There is considerable evidence that the builders
+of the Great Pyramid employed the “Grand
+Gallery” for astronomical observations (see
+“The Great Pyramid of Egypt,” in the present
+series), and other devices were employed. But
+no telescopes of any great power of magnification
+existed before the last century, while our
+present marvelous instruments of precision are
+the evolution of the present century.</p>
+
+<p>Telescopes are of two kinds: refracting and
+reflecting. Any small telescope exemplifies
+the former; the incoming light-rays are
+focussed by a series of lenses, and directly observed
+by the eye. In the employment of reflecting
+telescopes, however, another principle
+is employed: the incoming light-rays are caught
+and reflected by means of a curved mirror, and
+focussed on a lens, which in turn is inserted in
+an elaborate eye-piece, in which the light-rays
+are magnified and measured. Some of the
+modern instruments have a forty or more inch
+aperture, and are capable of enormous powers
+of magnification.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_SPECTROSCOPE_SPECTRUM_ANALYSIS">
+    THE SPECTROSCOPE: SPECTRUM ANALYSIS
+  </h2>
+</div>
+
+
+<p>For more than two thousand years, astronomy
+remained a purely mechanical and mathematical
+science, being limited to observations
+<span class="pagenum" id="Page_44">[Pg 44]</span>and deductions therefrom; but in 1860 the
+method of spectrum-analysis was discovered.
+This was a most revolutionary discovery, inaugurating,
+as it did, the whole science of astro-physics;
+and enabling us to know as much of
+the physics and chemistry of distant stars and
+nebulæ—their nature, constitution, and temperature—as
+we know of the planets of our own
+system! Even the existence of otherwise invisible
+stars has been demonstrated in this manner—their
+orbits, rate of motion, and mass.
+The science of astro-physics is now one of the
+most exact in the whole realm of science; and
+has only been rendered possible by the invention
+of the spectroscope. As this instrument
+plays such an important part in all astronomical
+research, a brief explanation of the instrument
+becomes necessary.</p>
+
+<p>If a ray of sunlight be passed through a glass
+prism, the ray is split up into its primary
+colors; so that, instead of a single spot of white
+light being visible a narrow band of brilliant
+colors is seen—ranging from red to violet. But
+this is not the most important part of the discovery.
+When this spectrum was closely examined,
+it was found to be crossed by numerous
+black bands of various thicknesses. Sometimes
+these occurred in groups, sometimes singly. By
+enlarging the spectrum by passing it through
+several prisms, as many as 3,000 of these bands
+could be counted. The nature and explanation
+of these strange bands of blackness remained
+long uninterpreted, however. It remained for
+Kirchoff, in 1860, to discover their uses and
+significance.</p>
+
+<p>Briefly, it is this. The chemical elements,
+<span class="pagenum" id="Page_45">[Pg 45]</span>when heated to a state of incandescence, present
+each one its own characteristic spectrum;
+each one has its own peculiar markings, or
+band of lines. No two elements are exactly like
+in their bands, as shown in the spectrum.
+Hence, whenever that particular marking is observed,
+it becomes certain that that element,
+and none other, is present. These spectra are
+very varied; iron, for example, has more than
+2,000 such bands, while lead and potassium have
+but one each.</p>
+
+<p>In this way—all the chemical elements having
+been studied, and their characteristic bands
+known—it became possible to explore the
+stars, planets and suns, and discover their
+chemical composition. For, no matter where an
+element was discovered—on this earth or on
+the remotest star—it would always cast its
+particular spectrum, when thus examined. The
+effect of all this upon astronomy can be perceived
+at once. Not only the heavenly bodies
+known to us, but those which have never been
+seen by human eye—even when aided by the
+most powerful telescopes—can be studied and
+their chemical composition and structure accurately
+determined. Here is progress indeed!</p>
+
+<p>All this becomes the more remarkable when
+we stop to consider the immense distances of
+space, and how widely separated the heavenly
+bodies are from one another. This may, perhaps,
+be shown by one or two illustrations.
+We are, roughly, about 93,000,000 miles from
+our own sun. Now, the majority of the stars
+we see are suns, like ours. The sun next removed
+from us in space is about 275,000 times
+as far from us as we are from our sun. The
+<span class="pagenum" id="Page_46">[Pg 46]</span>orbit of Halley’s comet, of which so much has
+been written lately, is some 3,280,000,000 miles
+in length; and this sporadic body, coursing
+through space at a speed 50 times greater than
+a rifle bullet, takes 75 years to complete its circuit.
+The nearest star has been calculated to
+be nearly 25 trillion miles away; while some
+of the stars are 40 times as far from us as
+that!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="PHOTOGRAPHY">
+    PHOTOGRAPHY
+  </h2>
+</div>
+
+
+<p>The second great engine of astronomical research,
+that has been added during the past
+century, is <i>photography</i>. By this means exact
+maps may be taken of the heavens at any hour
+of the night, and the precise position of thousands
+of stars determined with the utmost exactitude.
+A chart of the heavens, made in this
+manner, is not only more complete but more
+accurate than the combined observations of any
+number of men could possibly be. Moreover,
+the photographic plate will record the existence
+of stars which cannot be seen even with
+the aid of the most powerful telescopes. This
+is due to the fact that the plate gradually collects
+light, and its <i>cumulative</i> effect is noticeable,
+when its <i>immediate</i> effect cannot be perceived.
+This power of photographic plates is
+most valuable, and cannot be duplicated in any
+other manner. We are assured on good authority
+that “an ordinary good portrait camera
+with a lens three or four inches in diameter,
+if properly mounted so that an exposure of several
+hours can be made, will show stars so minute
+that they are invisible even in the great
+Lick telescope.” An international photographic
+<span class="pagenum" id="Page_47">[Pg 47]</span>chart of the heavens is now under way,
+which, when finished, will represent an accurate
+catalog of every visible sun, star, and
+planet, in the sky. After this, any unusual
+body should be quickly discovered.</p>
+
+<p>But photography is employed not only for
+mapping out the heavens, but for reaching the
+farthest stars. The moon and the sun have
+both been photographed repeatedly, and with
+most instructive results. The first good pictures
+of the moon were made by Dr. John W.
+Draper of New York City, in March, 1840. His
+son, Dr. Henry Draper, succeeded him in this
+work, and his photographs were considered the
+best until Rutherfurd began his remarkable
+work in 1865. After this, much important work
+was done in the Lick observatory, and elsewhere.
+The first picture of the sun was taken
+in 1845, by Fizeau and Foucault, on a daguerreotype
+plate. Sun spots, total eclipses, etc., are
+now studied in great detail by this means.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_TIDES">
+    THE TIDES
+  </h2>
+</div>
+
+
+<p>Every particle of matter attracts every other
+particle of matter throughout the entire Universe.
+The Sun and the Moon both exert a
+definite pull upon the earth; the moon particularly,
+being the earth’s satellite, is (so to say)
+held in place by the earth. The moon, exerting
+this definite pull, naturally influences the water
+of the earth most of all, because water is a
+fluid, mobile body. A heaping-up of the water
+then occurs—“high tide.” But the moon also
+attracts the earth to some extent; and the consequence
+of this is that the water on the opposite
+<span class="pagenum" id="Page_48">[Pg 48]</span>side of the globe is, as it were, left behind,
+which causes a heaping-up of the water
+there also. Hence, there are two high tides
+daily, with an interval of 12 hours between
+them, on opposite sides of the globe.</p>
+
+<p>When the sun and moon pull together, we
+have the highest tides—“spring tides.” When
+they do not pull together (being in different
+parts of the heavens) we have only the surplus
+pull of the moon over the sun, and the tides
+are consequently not so high. These are the
+“neap tides.” All tides act as a sort of check
+or brake upon the rotation of the earth on its
+axis—tending to slow down its speed to some
+extent. “Tidal waves” are due to a combination
+of special causes.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="GRAVITATION">
+    GRAVITATION
+  </h2>
+</div>
+
+
+<p>The mysterious influence or “pull” which
+various celestial bodies exert upon one another
+is known as gravity or gravitation. We know
+that masses of matter attract one another according
+to their size; the larger the body, the
+greater the force exerted, etc. Further, the
+influence decreases according to a definite law—according
+to the square of the distance between
+the two bodies. The innermost nature
+of gravitation is still largely a mystery—though
+various ingenious theories have been
+advanced in order to explain it. (See my article
+in “The Monist,” for July, 1913, and pp.
+44-46 of “New Discoveries in Science” in the
+present series.) Gravitation is supposed to act
+throughout the whole Universe, so that all
+<span class="pagenum" id="Page_49">[Pg 49]</span>celestial bodies mutually influence one another,
+to some extent. Its speed, mode or action, etc.,
+as well as its essence or true nature are, however,
+unknown even yet; they are still unsolved
+mysteries!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_ETHER">
+    THE ETHER
+  </h2>
+</div>
+
+
+<p>At all events, gravitation is thought to act
+through, or by means of, the Ether—the nature
+of which is still another mystery! Lodge, in
+his “Ether of Space,” has given some interesting
+figures as to the enormous strain which the
+ether must be supposed to transmit or carry.
+Lack of space, however, prevents a further discussion
+of this interesting question; a brief
+summary may be found on pp. 53-55 of my book
+on “Chemistry for Beginners,” in the series of
+Blue Books. For our present purposes, it need
+only be said that the ether is the only hypothetical
+connecting-link between celestial bodies—since
+there is no air or atmosphere in interstellar
+space. And it is across or by means of
+this ether that gravitation must be exerted.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="ATOMIC_ANALOGIES">
+    ATOMIC ANALOGIES
+  </h2>
+</div>
+
+
+<p>Recent investigations of the innermost structure
+of the atom have shown us that it is
+probably constituted on very much the same
+plan as our solar system—a central “sun” or
+proton, round which revolve the negative planets
+or “electrons.” This question I have treated
+more fully in my “Chemistry for Beginners,”
+pp. 42-44, to which the reader is referred.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_50">[Pg 50]</span></p>
+
+
+  <h2 class="nobreak" id="THUNDER_AND_LIGHTNING">
+    THUNDER AND LIGHTNING
+  </h2>
+</div>
+
+
+<p>The lightning flash is merely a huge electric
+spark, such as may be seen between the terminals
+of any electric machine. In cases of
+flashes, or forked lightning, this “spark” is seen
+directly. Sheet lightning is observed when the
+original flash is hidden behind clouds, and
+only its reflection or effects are seen. The
+rumbling of thunder is due to the reverberations
+and echoes of the original “peal.” The
+peal is thought to be due to the sudden rushing
+together of the molecules of the upper atmosphere,
+which have been rent asunder by the
+flash—a sort of vacuum created. Camille
+Flammarion has written an interesting book on
+“Thunder and Lightning,” which may be consulted
+for further details.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="FIREBALLS">
+    FIREBALLS
+  </h2>
+</div>
+
+
+<p>These are virtually the same as “shooting
+stars” (<i>q.v.</i>,) and no essential difference can be
+pointed to, as to their origin or nature. They
+are not mere “blobs” of lightning, but solid
+bodies which sometimes burst, with a great
+noise—though they are usually noiseless. Many
+of them appear to be pear-shaped, but they may
+be seen to change their size and shape during
+the period of visibility. Fireballs are often
+accompanied by a train of sparks.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="ATMOSPHERIC_ELECTRICITY">
+    ATMOSPHERIC ELECTRICITY
+  </h2>
+</div>
+
+
+<p>The surface of the earth is constantly
+charged with negative electricity of a static
+<span class="pagenum" id="Page_51">[Pg 51]</span>character. The upper atmosphere is usually
+charged positively, though, this may vary according
+to circumstances. The earth and upper
+air thus resemble two sheets of tin-foil, with
+the air an imperfect dialectric between them.
+This may be broken down, especially in wet or
+damp weather. The effects upon the mental
+and physical health are often very noticeable
+(see Dexter: “Weather Influences,” etc.)</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_EARTHS_MAGNETISM">
+    THE EARTH’S MAGNETISM
+  </h2>
+</div>
+
+
+<p>It has long been known that the magnetic
+pole does not coincide with the North Pole
+(or South Pole). The compass points to the
+magnetic north pole, and not to the true north
+pole. Lines of magnetic force seem to envelop
+the earth, terminating at the north and south
+poles, respectively. Although this is purely a
+terrestrial phenomenon, it is necessary to mention
+it here, since it has enabled us to explain,
+very largely, the remarkable manifestation
+known as</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_AURORA_BOREALIS">
+    THE AURORA BOREALIS
+  </h2>
+</div>
+
+
+<p>This is usually seen in northern climes, and
+the reason for this is now clear. We know that
+the corpuscles discharged from a Crookes tube
+are deflected by a magnet. These corpuscles
+are discharged in immense numbers by the sun,
+and rain upon our earth. Now, the earth is a
+magnet, and these corpuscles are caught by the
+lines of force girdling our earth, and carried
+towards the poles, where they find themselves
+in an atmosphere comparable with high vacua.
+<span class="pagenum" id="Page_52">[Pg 52]</span>They then begin to give out the shifting and
+darting lights characteristic of the cathode
+rays, causing a certain luminosity. These darting
+and shifting lights would, on this theory,
+account for the Aurora Borealis—which is also
+known to vary with the number of sun-spots.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="TIME_MEASUREMENT_OF">
+    TIME: MEASUREMENT OF:
+  </h2>
+</div>
+
+
+<p>Our divisions of time are purely arbitrary,
+and are all based upon the revolution of our
+earth upon its axis, which thus constitutes a
+gigantic clock. All other clocks, watches, etc.,
+are adjusted accordingly. This is really our
+only way of measuring time; subjective feelings
+are very illusory, and have to be checked-up
+by other means. The solar day is the basis
+of all our calculations—a month, a year, etc.,
+being only so many days in length. Our earth,
+therefore, is the clock by which we measure the
+time of the Universe!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="SPACE_MEASUREMENT_OF">
+    SPACE: MEASUREMENT OF:
+  </h2>
+</div>
+
+
+<p>The measurement of space is always a difficult
+problem, even for near-by objects (see
+my “Psychology for Beginners”). When applied
+to celestial bodies, it becomes immensely
+complicated, and the only wonder is that such
+apparently accurate measurements have in
+fact been made! Such measurements cannot,
+of course, ever be made <i>directly</i>, but must
+depend upon trigonometry and abstruse mathematical
+calculations. Most of them are based
+upon the following principles: If we observe
+<span class="pagenum" id="Page_53">[Pg 53]</span>a distant object from two different points-of-view,
+at a known distance apart, the angle
+formed by imaginary lines running from the
+object to one position, and to the other, can
+readily be calculated. Knowing this angle,
+much can be ascertained as to the size, distance,
+etc., of the distant body. If a distant
+star be viewed from opposite sides of the
+earth, we have here a known base-line of
+slightly more than 8,000 miles. But this is
+altogether too small for astronomical distances!
+A much longer base-line must be
+sought. Accordingly, observations are made
+of a distant star when the earth is (so to say)
+“north” of the sun, and further observations
+of the same star when the earth is (so to say)
+“south” of it—six months later, when the
+earth has traveled half-way through its orbit
+round the sun. The diameter of the earth’s
+orbit being known (186,000,000 miles, almost)
+we have here a base-line of this size for use
+in our measurement of the angle and subsequent
+calculations. Immense as this base-line
+is, however, it is too small for our purposes,
+for so immense are astronomical distances,
+that <i>no change whatever</i> can be observed in
+the relative positions of certain fixed stars—even
+when studied from such different positions
+in space! In other words, the star is so
+far distant that, when viewed from two positions
+in space, distant from one another nearly
+one hundred and eighty-six million miles, it
+appears to occupy the same position! But a
+mere summary of this question, and its details
+would involve an entire volume in itself!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_54">[Pg 54]</span></p>
+
+
+  <h2 class="nobreak" id="THE_INTERNATIONAL_DAY_LINE">
+    THE INTERNATIONAL DAY LINE
+  </h2>
+</div>
+
+
+<p>Inasmuch as our earth revolves on its axis,
+a new day is beginning at some different
+moment all round the world. This being the
+case, how are we to fix some definite and official
+“starting point” for our day—since the
+day officially begins at midnight, and not at
+sunrise? To determine this, an arbitrary International
+Day Line has been drawn, on the
+180th meridian—just half way round the globe
+from Greenwich. Fortunately, this falls in the
+Pacific Ocean, where there is almost no land.
+When the sun crosses this line, a new day
+begins. I have explained this more fully in
+my book “New Discoveries in Science” in the
+present series (pp. 40-42).</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="CALENDARS_ETC">
+    CALENDARS, ETC.
+  </h2>
+</div>
+
+
+<p>Our year is a little more than 365 days in
+length—in fact, nearly 365¼. Because of this
+fact, an extra day accumulates every four
+years; and to include this we add this extra
+day to February every “leap year.” In this
+way, our celestial bookkeeping is kept fairly
+accurate. Twelve months of 30 days each
+would give 360 days, with five days over. It
+was, however, found that five days was not
+enough, while five and a quarter was too
+much. It is interesting to note that Hipparchus,
+who flourished in the 2nd century B.&nbsp;C.,
+worked on this problem, and fixed 5 days and
+55 m., as the time required—a truly remarkable
+achievement, since it has since been
+<span class="pagenum" id="Page_55">[Pg 55]</span>found to be accurate to within less than six
+minutes.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="CURVED_SPACE">
+    CURVED SPACE
+  </h2>
+</div>
+
+
+<p>This, and various other problems connected
+with the Einstein theories may be found
+treated in No. 408 of the present series, “An
+Introduction to Einstein,” by William F. Hudgings.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_TEMPERATURE_OF_SPACE">
+    THE TEMPERATURE OF SPACE
+  </h2>
+</div>
+
+
+<p>The Earth is warmed by the sun’s rays, some
+of which are absorbed, while some are reflected.
+But these rays themselves possess no
+“heat”; they are merely minute vibrations in
+the ether. Heat is only present when they
+strike some solid body. Consequently the
+vast inter-stellar spaces are tremendously cold—probably
+at or about absolute zero (-273.10°C).
+Our earth is not heated directly, as a
+man is heated by standing in front of a blazing
+fire; but only by means of electro-magnetic
+undulations, which traverse millions of miles
+of space, colder than death, without heating
+them!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="LIGHT_IN_SPACE">
+    LIGHT IN SPACE
+  </h2>
+</div>
+
+
+<p>Space is also intensely dark; no light exists
+there save the faint twinklings of distant stars.
+The sun illumines our earth, because its rays
+are reflected from its surface; but space itself
+is intensely black, just as it is intensely cold
+It is a “cold world” indeed, once we have stepped
+off the little planet on which we dwell!</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+
+<p><span class="pagenum" id="Page_56">[Pg 56]</span></p>
+
+
+  <h2 class="nobreak" id="LIFE_IN_SPACE">
+    LIFE IN SPACE
+  </h2>
+</div>
+
+
+<p>All this being so, life in any form cannot
+very well exist in space—since the conditions
+for its existence are altogether absent. Arrhenius
+has, however, suggested, that the
+“germs of life” might possibly be carried across
+millions of miles of space on dust particles,
+propelled by the energy of light. This, however,
+is a pure theory, which has so far received
+no official proof.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="THE_CAUSES_OF_AN_ICE_AGE">
+    THE CAUSES OF AN ICE AGE
+  </h2>
+</div>
+
+
+<p>We know that our Earth has passed through
+several ice ages, in the past, and various astronomical
+theories have been advanced in order
+to explain this fact. Perhaps the most ingenious
+of these is that advanced by Sir Robert
+Ball (see his “The Cause of An Ice Age”).
+Very briefly, it is that the eccentricity of the
+earth’s orbit and the tilting of the polar axis
+causes an ice age, or the reverse. If the northern
+axis is tilted towards the sun, when nearest
+to it (so to say), then the northern hemisphere
+will enjoy a genial climate, and if the
+southern axis be thus tilted, the reverse conditions
+will prevail. This, and various other
+theories have, however, been discussed by Finger
+in his book on “The Ice Age,” in the present
+series, No. 327.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="WHY_DO_STARS_TWINKLE">
+    WHY DO STARS “TWINKLE”?
+  </h2>
+</div>
+
+
+<p>When we look at a star near the horizon,
+we at once notice that it twinkles, or “scintillates,”
+<span class="pagenum" id="Page_57">[Pg 57]</span>especially in the winter time. The
+phenomenon is purely atmospheric, and is due
+to waves of air of unequal density sweeping
+across the line of sight. When viewed through
+a telescope, this is sometimes magnified into
+actual dancing.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="WHY_DOES_THE_MOON_SOMETIMES_APPEAR">
+    WHY DOES THE MOON SOMETIMES APPEAR
+    LARGER?
+  </h2>
+</div>
+
+
+<p>It is well known that the moon often appears
+larger when rising or setting—i. e., near
+the horizon, than when it is overhead. The
+same is true of the Sun. It is hardly necessary
+to say that these celestial bodies have not
+<i>actually</i> increased or decreased in size! Why,
+then, should we perceive them larger at some
+times than at others?</p>
+
+<p>The reason for this is two-fold; psychological
+and optical. In the first place, the Heavens
+do not appear to us quite round, but somewhat
+flattened out, like a watch-glass. Hence the
+moon appears to be much further away when
+it rises than it does when it is overhead, with
+nothing between. The moon near the horizon
+is apparently larger because it seems further
+away. The second reason is that the refraction
+of the earth’s atmosphere gives this illusion of
+increased size.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="ARE_THE_PLANETS_INHABITED">
+    ARE THE PLANETS INHABITED?
+  </h2>
+</div>
+
+
+<p>This is a much-disputed point! Various astronomers
+(Schiaparelli, Lowell, etc.) have
+contended that they have almost indubitable
+evidence that Mars is inhabited by living beings
+<span class="pagenum" id="Page_58">[Pg 58]</span>like ourselves; other equally competent astronomers
+assert the contrary. Certainly, none
+of the planets of our own solar system, with
+the possible exceptions of Mars and Venus,
+could possibly be inhabited. That is universally
+granted. And we have no <i>direct</i> evidence of
+any other inhabited worlds throughout space.
+Analogy, however, forces us to believe that, of
+the millions of suns blazing in the heavens,
+many of them must be attended by a planetary
+system such as ours; and if such be the case,
+there is no reason why life should not originate
+and thrive thereon as well as upon our own
+planet. We have, however, no means of proving
+or disproving this directly.</p>
+
+<p>In our own system, Venus and particularly
+Mars offer possibilities. Venus probably always
+turns one face towards the sun, so that this
+side would be tremendously hot, while the
+other side would be frozen in perpetual ice.
+Mars is a possibility; and, as we know, great
+controversy has raged regarding the habitability
+of this planet, and as to its “Canals.” The
+interested reader may refer to Lowell’s “Mars
+as the Abode of Life,” and “Mars and Its
+Canals” for the affirmative, and to Maunder’s
+“Are the Planets Inhabited?” for the negative,
+side of this question.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+  <h2 class="nobreak" id="A_FEW_DEFINITIONS">
+    A FEW DEFINITIONS
+  </h2>
+</div>
+
+
+<p>What “Parallax” means. Since the earth revolves
+round the sun, the stars are apparently
+in slightly different directions from it at different
+times of the year. The difference in
+direction of a star as seen from two points on
+<span class="pagenum" id="Page_59">[Pg 59]</span>the earth’s orbit which are separated by the
+mean distance to the sun is the <i>parallax</i> of the
+star. In other words, the parallax of a star is
+the angle subtended by the major semi-axis of
+the earth’s orbit, as seen from the star.</p>
+
+<p>The “Orbit” of a moving body is its more or
+less circular passage through space, usually
+around another larger body, as our earth revolves
+round the sun. The “eccentricity” of the
+orbit consists in the fluctuations or variations
+from its exact path.</p>
+
+<p>The “Ecliptic” System. If we could see the
+stars near the sun, we should find that the Sun
+apparently moves eastward among them, completing
+one revolution in a year. Tracing such
+a path, it will be found that it more or less
+coincides with the celestial equator. The
+equator and the ecliptic intersect at two points;
+these points are the “equinoxes” the <i>vernal</i>
+equinox being the one at which the sun crosses
+the equator from south to north, and the
+<i>autumnal</i> equinox the other one.</p>
+
+<p>“Satellites.” These are smaller bodies which
+revolve round large ones, and, so to say, attend
+them. All except two of the planets are known
+to have satellites revolving round them, just
+as they revolve round the sun. Mercury and
+Venus have none; the earth has the moon;
+Mars has two little moons, only a few miles
+in diameter; Jupiter has four large satellites
+and four small ones; Saturn has ten, one of
+which is larger than Mercury; Uranus has
+four satellites, and Neptune one.</p>
+
+<p>The “Planetoids.” Between Mars and Jupiter
+a number of small bodies have been discovered,
+<span class="pagenum" id="Page_60">[Pg 60]</span>moving in a regular orbit; these have been
+called planetoids. If some planet has once occupied
+this mid-way position, and subsequently
+exploded, the fragments would occupy the position
+occupied by the planetoids. Whether or
+not this is their origin is a disputed point, which
+it would take us too far afield to consider
+here. They suggest the possibility.</p>
+
+<p>“Planets.” These are the bodies revolving
+round a central sun. Aside from those constituting
+our own solar system, we see no planets
+in space; we see suns, or stars; but if the
+latter have planets attendant upon them, we
+cannot see them.</p>
+
+<p>The point of the moon’s orbit nearest the
+earth is called the <i>perigee</i>; the furthest point,
+the <i>apogee</i>.</p>
+
+
+<hr class="chap x-ebookmaker-drop">
+<div class="chapter">
+<div class="transnote">
+  <p class="ph2" id="TRANSCRIBERS_NOTES">
+    TRANSCRIBER’S NOTES
+  </p>
+
+
+<p>Author’s spelling of “dialectric” has been retained.</p>
+
+<p>Inconsistencies in hyphenation have been left unchanged.</p>
+
+<p>Typos corrected:</p>
+
+<ul>
+<li><a href="#Page_1">Title page</a>: missing opening quote in “Psychology for Beginners”</li>
+
+<li><a href="#Page_13">Page 13</a>: “concenses” to “consensus”</li>
+
+<li><a href="#Page_17">Page 17</a>: “equitorial” to “equatorial”, "Myriads" to
+"myriads" (lowercase)</li>
+
+<li><a href="#Page_49">Page 49</a>: “on my book” to “of my book”</li>
+
+<li><a href="#Page_54">Page 54</a>: “litle” to “little”</li>
+
+<li><a href="#Page_59">Page 59</a>: “Unanus” to “Uranus”</li>
+</ul>
+</div>
+</div>
+
+<div style='text-align:center'>*** END OF THE PROJECT GUTENBERG EBOOK 78112 ***</div>
+</body>
+</html>
diff --git a/78112-h/images/cover.jpg b/78112-h/images/cover.jpg
new file mode 100644
index 0000000..434127a
--- /dev/null
+++ b/78112-h/images/cover.jpg
diff --git a/LICENSE.txt b/LICENSE.txt
new file mode 100644
index 0000000..6c72794
--- /dev/null
+++ b/LICENSE.txt
@@ -0,0 +1,11 @@
+This book, including all associated images, markup, improvements,
+metadata, and any other content or labor, has been confirmed to be
+in the PUBLIC DOMAIN IN THE UNITED STATES.
+
+Procedures for determining public domain status are described in
+the "Copyright How-To" at https://www.gutenberg.org.
+
+No investigation has been made concerning possible copyrights in
+jurisdictions other than the United States. Anyone seeking to utilize
+this eBook outside of the United States should confirm copyright
+status under the laws that apply to them.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e6ae545
--- /dev/null
+++ b/README.md
@@ -0,0 +1,2 @@
+Project Gutenberg (https://www.gutenberg.org) public repository for eBook #78112
+(https://www.gutenberg.org/ebooks/78112)