of miles from the sun. It completes its revolution in its orbit in four years and four months, and is supposed to turn on its axis in twentyseven hours. Pallas is about two hundred and sixty-three millions of miles from the sun, and revolves in its orbit in four years and seven months. The time in which it turns on its axis has not yet been ascertained. Its diameter is computed at little more than seventy-nine miles; so that a human inhabitant, if it had one, could round go his world, in one of our steam-carriages, in the space of two or three hours! Its whole surface has been said to about equal the size of the kingdom of Spain. You will judge from this of the general sizes of all these lesser planets; How long is its revolution round the sun? How far is Pallas from the sun? How long is it revolving round the sun? for they are a little family by themselves, and have each a family likeness to the remainder. Ceres is at the same distance from the sun as Pallas, but revolving in another path or orbit. It revolves round the sun in nearly the same time as Pallas. In performing its revolution, it crosses the orbit of the latter. These four little planets have been discovered by astronomers but within a few years past. They are very small, and it has been imagined, by some persons, that they once formed one great planet, which was burst asunder by a terrible convulsion, and separated into small parts. I suppose you know that stones have sometimes fallen from the air upon the earth. These stones are called aërolites, or meteoric stones. Now it Describe Ceres. Is there much known of these four lesser planets? What have some persons imagined? has even been idly imagined, that these meteoric stones, which have also been fancied to come from the moon, and have thence been denominated selenites, have come down upon the earth through the bursting of the great planet out of which these lesser ones may have been formed! We shall have more to say presently, about these aërolites. CHAP. XLII. ABOUT THE FIFTH NEW PLANET, OR PLANET DISCOVERED IN ITALY, IN THE YEAR 1836, BY SIGNOR CACCIATORE. BUT newer still, than either of the four little planets of which I have just now told you, is a fifth little planet of this group, discovered only last year (1836) by the Italian astronomer Cacciatore. I have not yet heard of any name that has been given to this planet; but its existence is confirmed to us by the testimony of the wellknown and estimable astronomer and natural philosopher, M. Valz, of Nismes; who estimates its year, or period of revolution in its orbit, at three of our terrestrial years. In my representation of the planetary system, at page 176, and page 202, I have ventured to place this New Planet of Cacciatore between Mars and Vesta. CHAP. XLIII. ABOUT JUPITER. Ar an immense distance beyond Mars, and beyond these lesser planets, is Jupiter, the largest planet of the system. Its diameter is eightynine thousand miles, and it is more than a thousand times larger than the earth. It is four hundred and ninety millions of miles from the sun, and performs its revolution round it in twelve years. It turns round on its axis in less than ten hours. Its days and nights, therefore, are not half so long as ours! The degree of heat and light in Jupiter, is reckoned at twenty-five times less than on the Where is Jupiter? Which is the largest planet? What How is the diameter of Jupiter? long is its revolution round the sun? How long is it turning on its axis? What is the length of the days and nights in JupiWhat is its degree of light and heat? ter? |
