San Diego Observatory, September 1, 1854.
Lectures on AstronomyPart I
CHAPTER I
The term Astronomy is derived from two Latin words,Astra, a star, and onomy, a science; and literally means the science of the stars. "It is a science," to quote our friend Dick (who was no relation at all of Big Dick, though the latter occasionally caused individuals to see stars), "which has, in all ages, engaged the attention of the poet, the philosopher, and the divine, and been the subject of their study and admiration."
By the wondrous discoveries of the improved telescopes of modern times, we ascertain that upward of several hundred millions of stars exist, that are invisible to the naked eyethe nearest of which is millions of millions of miles from the Earth; and as we have every reason to suppose that every one of this inconceivable number of worlds is peopled like our own, a consideration of this factand that we are undoubtedly as superior to these beings as we are to the rest of mankindis calculated to fill the mind of the American with a due sense of his own importance in the scale of animated creation.
It is supposed that each of the stars we see in the Heavens in a cloudless night is a sun shining upon its own curvilinear, with light of its own manufacture; and as it would be absurd to suppose its light and heat were made to be diffused for nothing, it is presumed farther, that each sun, like an old hen, is provided with a parcel of little chickens, in the way of planets, which, shining but feebly by its reflected light, are to us invisible. To this opinion we are led, also, by reasoning from analogy, on considering our own Solar System.
The Solar System is so called, not because we believe it to be the sole system of the kind in existence, but from its principal body, the Sun, the Latin name of which is Sol. (Thus we read of Sol Smith, literally meaning the son of Old Smith.) On a close examination of the Heavens we perceive numerous brilliant stars which shine with a steady light (differing from those which surround them, which are always twinkling like a dewdrop on a cucumber-vine), and which, moreover, do not preserve constantly the same relative distance from the stars near which they are first discovered. These are the planets of the Solar System, which have no light of their ownof which the Earth, on which we reside, is onewhich shine by light reflected from the Sunand which regularly move around that body at different intervals of time and through different ranges in space. Up to the time of a gentleman named Copernicus, who flourished about the middle of the Fifteenth Century, it was supposed by our stupid ancestors that the Earth was the center of all creation, being a large, flat body resting on a rock which rested on another rock, and so on "all the way down"; and that the Sun, planets and immovable stars all revolved about it once in twenty-four hours.
This reminds us of the simplicity of a child we once saw in a railroad-car, who fancied itself perfectly stationary, and thought the fences, houses and fields were tearing past it at the rate of thirty miles an hour;and poking out its head, to see where on earth they went to, had its hata very nice one with pink ribbonsknocked off and irrecoverably lost. But Copernicus (who was a son of Daniel Pernicus, of the firm of Pernicus & Co., wool-dealers, and who was named Co. Pernicus, out of respect to his father's partners) soon set this matter to rights, and started the idea of the present Solar System, which, greatly improved since his day, is occasionally called the Copernican system. By this system we learn that the Sun is stationed at one focus (not hocus, as it is rendered, without authority by the philosopher Partington) of an ellipse, where it slowly grinds on for ever about its own axis, while the planets, turning about their axes, revolve in elliptical orbits of various dimensions and different planes of inclination around it.
The demonstration of this system in all its perfection was left to Isaac Newton, an English Philosopher, who, seeing an apple tumble down from a tree, was led to think thereon with such gravity, that he finally discovered the attraction of gravitation, which proved to be the great law of Nature that keeps everything in its place. Thus we see that as an apple originally brought sin and ignorance into the world, the same fruit proved thereafter the cause of vast knowledge and enlightenment;and indeed we may doubt whether any other fruit but an apple, and a sour one at that, would have produced these great results;for, had the fallen fruit been a pear, an orange, or a peach, there is little doubt that Newton would have eaten it up and thought no more on the subject.
As in this world you will hardly ever find a man so small but that he has someone else smaller than he, to look up to and revolve around him, so in the Solar System we find that the majority of the planets have one or more smaller planets revolving about them. These small bodies are termed secondaries, moons or satellitesthe planets themselves being called primaries.
We know at present of eighteen primaries, viz.: Mercury, Venus, the Earth, Mars, Flora, Vesta, Iris, Metis, Hebe, Astrea, Juno, Ceres, Pallas, Hygeia, Jupiter, Saturn, Herschel, Neptune, and another, yet unnamed. There are distributed among these, nineteen secondaries, all of which, except our Moon, are invisible to the naked eye.
We shall now proceed to consider, separately, the different bodies composing the Solar System, and to make known what little information, comparatively speaking, science has collected regarding them. And, first in order, as in place, we come to
THE SUNThis glorious orb may be seen almost any clear day, by looking intently in its direction, through a piece of smoked glass. Through this medium it appears about the size of a large orange, and of much the same color. It is, however, somewhat larger, being in fact 887,000 miles in diameter, and containing a volume of matter equal to fourteen hundred thousand globes of the size of the Earth, which is certainly a matter of no small importance. Through the telescope it appears like an enormous globe of fire, with many spots upon its surface, which, unlike those of the leopard, are continually changing. These spots were first discovered by a gentleman named Galileo, in the year 1611. Though the Sun is usually termed and considered the luminary of day, it may not be uninteresting to our readers to know that it certainly has been seen in the night. A scientific friend of ours from New England (Mr. R.W. Emerson) while traveling through the northern part of Norway, with a cargo of tinware, on the 21st of June, 1836, distinctly saw the Sun in all its majesty, shining at midnight!in fact, shining all night! Emerson is not what you would call a superstitious man, by any meansbut, he left! Since that time many persons have observed its nocturnal appearance in that part of the country, at the same time of the year. This phenomenon has never been witnessed in the latitude of San Diego, however, and it is very improbable that it ever will be. Sacred history informs us that a distinguished military man, named Joshua, once caused the Sun to "stand still"; how he did it, is not mentioned. There can, of course, be no doubt of the fact, that he arrested its progress, and possibly caused it to "stand still";but translators are not always perfectly accurate, and we are inclined to the opinion that it might have wiggled a very little, when Joshua was not looking directly at it. The statement, however, does not appear so very incredible, when we reflect that seafaring men are in the habit of actually bringing the Sun down to the horizon every day at 12 Meridian. This they effect by means of a tool made of brass, glass, and silver, called a sextant. The composition of the Sun has long been a matter of dispute.