The family celestial

Dedication

In particular, to the bright boys and girls who were pupils in the Monetta High School during the scholastic years 1908-09 and 1909-10, and who manifested such a lively interest in and evinced such a desire for a knowledge of astronomy ; and, in general, to the boys and girls of the commonwealth and of the world who may never be able to take a course in astronomy, but who desire to know at least some of the fundamentals and phenomena of this most comprehensive science.

Ye stars! which are the poetry of Heaven!

If in your bright leaves we would read the fate Of men and empires — 'tis to be forgiven,

Contents

PAGE

I. Our Great Luminary 15

II. Our Satellite 26

Preface

Statistics show that only a very small percentage of our boys and girls ever take a college course ; and many of those who do complete their course never study Astronomy at all. Their time and effort are spent on something else in this great commercial age, and they are not led to comprehend the beauty of Astronomy. If once they were brought to a knowledge of its glory and splendor, in a great many cases they would pursue a study of the science for the sake of culture alone.

Astronomy is one of the most beautiful sciences which it is our pleasure and privilege to study. Nothing else, unless it be Geology alone, touches so many sides of life and so many phases of nature; it is extremely comprehensive — it is a study of the Universe.

The writer of this little volume, when a teacher in the public schools, observed how intensely interested not only the boys and girls in the high-school department, but also those in the lower grades, became when the glory of the heavens was unfolded to them; and this intense interest on their part has led the author to decide to publish the set of short essays which he outlined in talking to his pupils on this subject.

These are for the most part things known for a long time, and expressed again and again; but the writer trusts that the mode of expression used may commend itself to those who read, and that every boy and girl may, therefore, be prompted to learn the story of the Celestial Family. We know of nothing more pleasant to the possessor than having his mind stored with a knowledge of wonderful facts and suitable expressions in which to clothe them. He is thus marvelously aided in conversation, and also in the production of themes in the school room. His outlook on life is changed, and he gazes upon nature and her marvels with eyes of rapture and of gladness.

This little work consists of fifteen short chapters — one on the Sun, Moon, and each of the Planets; one on the Solar System ; one on Gravitation, on the Comets, the Shooting Stars ; and one on the Suns in Space. The plan follows the general outline of writers on this subject, beginning with the Sun — the center of the system — and proceeding outward, taking up the planets in their regular order with respect to distance from the sun. The chapter on Gravitation is essential to a true understanding of the many intricate problems relating to the actions of the planets, comets, and meteors, and so it is worked in also.

Much study and reading have been given to the preparation of this little work. Every course taken and every book read had something to commend itself to the writer, who is indebted to it for the part given and the thought suggested ; but he is most of all under obligation to the works of Sir Robert Ball, and he would recommend to all who may read this little volume that they follow it up with a study of the great Englishman's works for lay readers. Many expressions and illustrations in this little Book are derived from the works of our eminent contemporary above referred to, and to him the writer tenders his gratitude.

The author is under obligation to the Yerkes Observatory for permission to use their photographs, and he thanks them for the courtesy.

It is the wish of the author that this little volume may find its way into the life of thousands of boys and girls and older people as well, and, cherishing this fond hope, he sends it forth on its mission among the school children of the land.

M. A. S.

Kingstree, S. C.

September 21, 19 12.

Yerkes Observatory. (Exterior View.)

OUR GREAT LUMINARY

The spacious firmament on high,

With all the blue ethereal sky, And spangled heavens, a shining frame,

Their great Original proclaim: Th' unwearied sun, from day to day,

Does his Creator's power display, And publishes to every land

The work of an Almighty hand.

Nothing better reveals to us the mighty majesty and power of God than a contemplation of the heavens. The great ideas of time, and space, and magnitude, and velocity, and number, and motion, and power claim our attention and elevate us in the scale of being. By contemplating the marvelous glories of the universe, we gain a clearer insight into the will of the Creator, and find exemplified more fully than in any other way the nothingness of man and the superior majesty of God.

Again, when these noble thoughts invest the attention of our minds, we are diverted from the petty feuds and factions of mankind and are made to realize that there is more in life than is indicated by the ripplings on its surface. The deeper current of life's meaning flows as an undertow, reverting and rebounding from every individual and reaching throughout the universe of creation; for no one can live to himself alone. As a mutual attraction is prevalent from one heavenly body to another, so does a mighty force pervade the entire social universe, acting and reacting upon every member of its system.

We can gain no better idea of the bountiful plenitude of nature than from a consideration of the sun himself — our great and glorious luminary, dispensing light and heat to the encircling worlds and making possible life in some of its multifarious forms. Many people go through life without knowing anything whatever about the distance, relative size, force of gravity, etc., of the sun and his attendant planets and satellites. Of course, nothing is far or near, great or small, heavy or light, dense or rare, unless compared with something else varying from itself in these essential qualities and characteristics. A cat is small when compared with a lion, but large when compared with a mouse. Likewise, the earth is large when compared with the moon, but dwindles into insignificance when contrasted with the enormous volume of the sun.

If we chose a football to represent the sun, we should have to take a grain of sand or a very small shot to show the relative size of the earth. One hundred of these grains placed side by side would extend across the diameter of the football; and the number cubed would give one million, thus indicating that the sun is one million times the size of the earth. In other words, if one million globes the size of the earth were melted down and poured into one, its volume would not equal that of the sun, for in reality the sun is somewhat more than a million times the size of the earth. The moon is about 239,000 miles from the earth, and the

The Sun's Disk.

di; of the sun is about 866,000 miles ; now, if the

sur .\ : placed where the earth is, his volume would extent jre than 190,000 miles beyond the orbit of the moon; or, to reverse the position, if the sun were placed where the moon is, his volume would extend more than 190,000 miles on the opposite side of the earth. If a railroad track were laid around the earth, an express train traveling at the rate of sixty miles per hour would pass around the earth in a little more than seventeen days ; but at the same rate of speed the train would require five years to engirdle the enormous volume of the sun. These are contemplations which cause us to wonder and to look with increasing interest upon the magnitude of the universe and the majesty of the orbs which revolve in the immensity of space.

The mean distance of the sun from the earth is approximately 93,000,000 miles. This number is so vast that it is impossible for the finite mind to grasp its tremendous magnitude. It can be made more intelligible, however, by an effort to count the number of miles. By allowing the clock to do the work for us, we find that in one hour the clock will make 3,600 ticks, and in twenty-four hours it will make 86.400 ticks. If we divide the number which the clock counts in one day into 93,000,000, we obtain as a result 1,076 days, or a little less than three years for the clock to perform the stupendous task.

If a railway ran from the earth to the sun, we might calculate the period of time that a train, running at the rate of sixty miles per hour, would take to traverse the mighty journey. In one day the train would travel 1,440 miles, and in one year it would cover the tremendous distance of 526,000 miles. This number divided into 93,000,000 gives as a result nearly 177 years. Truly a long period of time! A man traveling on this great journey could never hope to reach his destination. His great-great grandchildren might live to view the marvelous glories of our splendid luminary. Had the train left the earth when the "Father of his Country" first saw the light, it would just now be ending its stupendous journey. Now, we may ask ourselves the question : How do astronomers measure these vast distances? Since we are considering the sun, we may make an effort to explain how his distance is measured. Two astronomers station themselves as far from each other as possible, which we know is about 8,000 miles (the diameter of the earth), and take observation on the sun. Thus the number of degrees in the angle at each observer as he gazes at the sun is found; from which, knowing the distance between them, they are able to compute the distance of the sun. Eclipses, the transit of Venus across the face of the sun, and other celestial phenomena also, aid in computing the exact distance of the sun; and, as all these methods concur in producing approximate results, the distance from the earth to the sun is a well ascertained quantity.

Some seemingly well informed folk say that astronomy is all guesswork and conjecture, and that they do not credit the so-called wonderful discoveries of the astronomers. To these the scientists may well say that it matters little whether they believe them or not, since it does not make these claims any the less meritorious and true for them to doubt the veracity of the statements made by the observers of the heavens. Astronomy is an exact science: the distances of the heavenly bodies are more accurately known than the distances between our great cities. If it were not an exact science, the recurrence of certain celestial phenomena could not be predicted with such unerring mathematical accuracy. Every claim and every statement is proved by mathematical analysis and mathematical exactitude. The recurrence of eclipses, the approach of invisible comets, the prediction of planetary transits, and a multitude of other wonderful phenomena, are wrought out with marvelous skill and exactness. It is indeed wonderful that the mind of man is capable of making such profound calculations and speculations with respect to the great and limitless universe of space lying out beyond the confines of our earth, this "mould of hopes and fears" upon which we spend the moment of time allotted us for the preparation of a nobler existence.

All of us are familiar with the heat of the sun. We know that the beauties of the earth are made possible by the engendering rays of the sun, as they flash across the gulf of space which separates us from that body, and that every spring-tide is made welcome by the resurrection called into existence by this generous heat ; then we come to the conclusion that the sun must be so intensely hot that on earth it would be utterly impossible for us in our chemical laboratories or metallurgical establishments to produce heat approximating his in the slightest degree.

Solar prominences dash away from the luminary with a terrific speed, often attaining the elevation of 20,000 miles, while it is recorded that one of these great tongues of flame extended more than one-third of the sun's diameter from his surface — a distance of 350,000 miles. We must not get the idea that the sun concentrates all of his heat and light upon the earth for our benefit, for our little planet intercepts but the 2,ooo,ooo,oooth part of his generous rays. All of the heat and light intercepted by the planets and satellites falls as far short of exhausting the supply emitted by the sun as the inhalation of a wren from utilizing the tremendous envelope of atmosphere which surrounds the earth.

There are different ways by which we may perceive the heat of the sun. A common sun-glass, by refracting and concentrating the rays of light and heat, may be used to ignite substances, which is a direct proof of the sun's wonderful heat. Some man of ingenuity and skill has so arranged a sun-glass above the touch-hole of a cannon that, at the moment when the sun reaches the highest point in his daily journey — the meridian of any given place — the heat concentrating through the glass ignites the powder placed in the touch-hole and causes the cannon to be fired. Thus we see that the sun himself, though millions of miles distant, is made to announce the midday hour. By using a peculiar glass globe, which focuses the light and heat, we can construct a tell-tale for the sun. A piece of paper is so arranged that, when the rays of the rising sun passing through the globe strike it, a black streak is burned across the paper. When a cloud intervenes and intercepts the rays, the paper is left unscorched, thus providing the means by which the number of hours of sunshine and of shadow may be determined.

It would be very inconvenient, tiresome, and monotonous to us if we had day or night all the while. What a beautiful and benign provision of nature that gives us alternate hours of light and darkness ! If we had day all the time, it would become exceedingly wearisome on account of its unbroken uniformity; for we should then have to arrange our work according to some ill-conditioned schedule. And, on the other hand, if the shades of darkness continued for long and indefinite periods, it would become extremely oppresive and burdensome to us. We should probably find ourselves in a precarious position somewhat like a certain cock in the Arctic regions. After crossing the Arctic Circle, since the sun did not descend' below the horizon, but continued to shine with unabated vigor for several months together, the cock, hitherto very punctual in announcing the hour of dawn, knew not when to crow. At times he would take to violent fits of crowing, and later, since his former efforts availed nothing, he would sulk in his gloom and sadness, like Achilles of old, until in sheer desperation he threw himself into the frozen waters of the Northern Ocean.

To account for the recurrence of day and night the ancients made many conjectures. Not knowing that the earth rotates on her axis, as a consequence of which day and night are respectively produced as one side of the earth is brought into the sun's light leaving the other in shadow, some of the ancients said that the sun was an archer god borne in a flaming chariot across the concave of the heavens. Others gave it as their opinion that Vulcan, the god of fire, spent a long period of time in forging a flaming firebrand capable of illuminating the terrestrial regions, and that every morning he would throw the sun across the sky and then, with all of his wonderful speed, he would sail around the frozen north to catch in his boat the sun as it fell into the waters of the west. This was a very pretty story ; but it was very tiresome work for poor old Vulcan. But how did the ancients account for the difference in the length of the days in summer and in winter? They said that, as the fire-god in summer threw the sun with such terrific force that he would have to struggle with all of his might to get back to the east in time for the next day to begin, these efforts so weakened and exhausted Vulcan that in winter he could throw the sun only a short distance across the heavens. These outbursts of energy on the part of the fire-god accounted for day and night and for the difference in their length in summer and winter.

This was a beautiful theory, but it was altogether inadequate to satisfy the inquiring mind of philosphers and scientists ; and we need not be surprised to learn that years and years later the solar system was comprehended in its true significance, with the sun as the central luminary and the earth as an attendant planet This wonderful discovery on the part of the astronomers changed the whole theory of the universe. Instead of the sun, moon, and stars revolving around the earth as a common center, the stars are suns, and the planets and satellites are simply attendants. If our little sun and his retinue of followers were instantly blotted out of existence, it would make no material difference in the vast universe, and only a little point of light would cease to glow.

The Corona.

Of all the celestial bodies, we owe most, yea everything, to the sun. Were it not for the sun, our little earth would be cold and dark and dreary, an unfit habitation for such beings as the members of the human race. His light and heat make possible the growth of every bud and blossom; the corn develops under the magic touch of his benign influence; the cotton whitens beneath the blue skies as a result of his fostering rays, and the fruits are struck through with juicy ripeness as he causes the breath of summer to pass over the land. The sun's heat raises water from the ocean in the form of vapor, and then precipitates that vapor as rain to refresh the earth and cheer the flowers, to fill our rivers and waft our mighty ships to the sea. The sun's rays beating on the broad expanses of land give existence to the breezes and winds which turn our wind-mills, sail our air-ships, and waft our vessels across the mighty deep. Of course, the atmosphere belongs to the earth, but the heat of the sun sets it in motion and causes it to serve us in turning our machinery and in bearing vapor to the otherwise parching lands.

In prehistoric ages when the earth, as a result of the sun's rays and her own inherent heat, was far more intensely heated than at present, the mighty vegetation of the coal period was produced ; and now, while we enjoy the many comforts and conveniences made possible by the numberless uses to which coal is put, we are but enjoying the sunbeams which shone on the earth countless millenniums ago. In the form of coal that heat has slumbered for ages, till we in this later day summon its activities to our service. Plants and trees in growing appropriate heat, and then give off this heat according to certain chemical agencies and conditions. A piece of wood, wlren consumed by fire, gives forth perceptive heat; but the same wood, if allowed to decay, emits an identical amount of heat, although given off during such a long interval of time that we are not able to perceive it.

It is the power of the sun stored up in coal and wood that runs our steam engines, turns our factories and cotton mills, and drives our locomotives over the land and our steamers and battleships across the sea. It is the light of the sun stored up in material products that beams from the lights in our cities, making them places of industry and of thrift. Every industry and enterprise on the earth is in some way connected with the potent influence of the sun. And yet the greatest amount of the sun's engery that we are able to appropriate falls as far short of exhausting the boundless supple emitted by that glorious body as the sip of a bird fails to exhaust the volume of some mighty river as it meanders to the sea.

The governments of the earth — and they are to be commended for it — are endeavoring to reserve their forest supply, that future generations may not be deprived of and made to suffer from a loss of the conveniences which result from the bounties of nature; but, so long as the sun continues to shine and supply the earth with light and heat, we shall be cared for; for scientists will so arrange glass mirrors or some other device as to reflect, concentrate, and store up sufficient heating and illuminating energy to operate and manipulate every industrial enterprise existing on the earth. A few square feet of surface contain sufficient energy in the form of solar heat to propel an engine of colossal proportions. The tides, engendered by the influence of the moon and sun, may also be used as a source of power, greatly increasing the facilities of the human race. The future shall witness the utilization of this hitherto unemployed energy, by which the teeming millions of the earth shall prosper. As great and important as is the sun, he has many rivals in the infinitude of stars which stud the universe ; but these countless suns have very little effect, if any, on the earth and our existence, since they are so far from us that they are not capable of contributing to our necessities. Our own immediate sun, dispensing to us light and heat and supplying our needs and making the earth a place of beauty and of I^appiness, is the controller of our destinies. To him we look for sustenance, and in him we find our plenitude for the future development which the coming centuries shall witness on this earth. Yet the poet tells us ;

"The sun is but a spark of fire, A transient meteor in the sky;

The soul, immortal as its Sire, Shall never die"

OUR SATELLITE.

Soon as the evening shades prevail, The moon takes up the wondrous tale,

And, nightly, to the listening earth, Repeats the story of her birth;

While all the stars that round her burn, And all the planets in their turn,

Confirm the tidings as they roll, And spread the news from pole to pole.

Our satellite is about 239,000 miles from the earth, being only the one three hundred and eighty-ninth part of the sun's distance. In comparing the earth and the sun, we found the sun to be many times larger than the earth; but, when we compare the earth and the moon, we find the moon to be many times smaller. If the moon were drawn nearer and nearer to us, however, she would after a while exhibit the appearance of a vast continent stretching out above the earth. We might, figuratively speaking, call the planets sons and daughters of the sun, and the satellites we might name his grand-children. The moon, then, is the earth's daughter and the sun's granddaughter.

At this point it might be well for us to give the beautiful nebular theory, which has been propounded by the astronomers for the purpose of accounting for the singularities and the origin of the solar system. It is believed that in ages vastly remote the planets and their satellites were united with the sun in a nebulous mass. This mass was diffused throughout a certain portion of space, and parts of it on becoming semi-solid were detached from the main body, the outermost planets being the first formed. As these masses varied in volume, all being far smaller than the sun, the larger ones were attracted by him and began to swing in their orbits at their relative distances from the central luminary ; while the smaller bodies near by were attracted by the larger, and began to whirl around them as satellites. Perhaps millions of these small bodies — fragments — were so far from any of those which we know as planets, that the sun exerted more magnetic force upon them than did the planets; and, therefore, they began to swing in an orbit around the sun, thus failing to become satellites for the attendant planets. For aught we know, these small bodies pursue courses around the sun as true as the mightiest globe in our system. They are too small, many of these planetoids, to intercept and reflect sufficient sunlight to enable us to see them ; but some of the Asteroids, minor planets, may be seen through powerful telescopes.

The planetesimal theory of the formation of the solar system, and of every system in the universe, is based upon the hypothesis that a great nebulous mass was affected with a spiral motion which caused nuclei to form, and about each of these gathered more or less material which solidified in time into a planetary body. It is barely possible that the entire mass may have, by this spiral motion, formed one vast body, and, by contracting and cooling outwardly for ages, the formation of internal gases might have been the result. After being pent up for ages, the gases might have caused a tremendous explosion which sent the nebulous matter in all directions, and this later congealed through the process of cooling into more or less solid forms.

We cannot say for a certainty that the solar system was formed as above described in the so-called nebular and planetesimal theories. Suffice it to say, however, that the system exists in harmonious accord and beauty, controlled by the universal laws of nature and of nature's God. The solemnity of this thought is such that we are led further on in our contemplation of the heavens; and the more we think about the solar system in the present form of its existence, the more are we impressed with its significant beauty and development throughout the ages of the past.

All of these masses emitted from the main body, if either of these theories be correct, were of the same temperature as the sun himself when they began their movements of rotation and revolution; but, since smaller bodies when heated cool much more rapidly

£8 than larger ones, some of these masses have become so cool that they have now ceased to glow from their own inherent heat and shine only by reason of the reflected light from the sun. We can readily illustrate to our mind the difference of time that objects take in cooling, or radiating their heat, if we place a wire and a rod of iron in a furnace and heat them to incandescence: the wire will become cool enough to handle long before the iron ceases to glow.

Just so is it in the case of the planets and satellites with reference to the sun, and to one another also according to their relative magnitudes. These have radiated so much of their heat that they would be invisible if it were not for the light of the sun which they intercept and reflect, thus making it possible for them to shine and be seen. There may be bodies invisible swinging within the confines of the solar system, which we are not able to see because they are so cold that no inherent heat emits light from them, and also because they are so far away that what little sunlight is intercepted by them is so excessively feeble that we are not able to perceive it even with a powerful telescope; but such bodies must be so small that they can exert no appreciable influence upon the visible members of the system. Indeed, the outermost planet yet discovered — Neptune — is invisible to the unaided vision, and his presence was known by mathematical analysis before he was detected by the telescope. If large bodies, other than those known, existed in the solor system in comparatively close proximity to the familiar planets, they could and would be detected and discovered because of their attractive influence on the various members of our system in causing them to be dilatory or deviatory in their respective movements. Very small meteoric objects are not capable of exerting a perceptive force in this direction; and, therefore, it is impossible for us to tell their whereabouts until they dash into our atmosphere.

In studying the sun, we had occasion to say that he is more than a million times the size of the earth; but, when we begin considering the moon, we find her somewhat less in size than the fiftieth part of the earth and weighing about one-eightieth as much, since her materials are of lighter proportions or are not so compactly held together. The sun, since he has such a tremendous volume, being, as above set forth, over fifty million times that of the moon, is so large that he glows with wonderful heat ; but the moon, on the other hand, is so small, comparatively speaking, that she has long since become cold and lifeless. Our little experiment with the wire and rod of iron is thus exemplified on a marvelous scale.