Some of the mountains have been calculated to be about five miles in height. The Moon is supposed to have very little, if any atmosphere; and, consequently, cannot be inhabited by beings like ourselves. CHAPTER X. MARS. MARS is the fourth planet from the Sun, and is the smallest, except Mercury. It is about one seventh of the size of the Earth. The Axis of Mars is inclined towards its orbit about 30 degrees. The Seasons, therefore, of Mars, resemble those of the Earth, but are nearly twice as long. The Oblateness of Mars' figure is more than twenty times as great as that of the Earth. Mars may be distinguished from the other planets, by its red, fiery color. The Disc of Mars, when viewed with a telescope, exhibits the outlines of apparent continents and seas; the How high are the mountains in the moon? Has the moon any atmosphere? Is she inhabited? What is Mars? What is its size? What is the inclination of its axis? What seasons has it? What is said of its figure? How may it be distinguished? What does its disc exhibit when viewed with a telescope? continents appearing of a ruddy, and the seas of a greenish color. The Disc of Mars also exhibits, brilliant white spots, alternately at each of the poles. These spots are supposed to be accumulations of ice and snow; because they disappear at the pole as summer advances upon it. The ruddy color of Mars is supposed to arise from a very dense atmosphere which surrounds it. Mars is sometimes gibbous, but never horned; be cause it does not pass between us and the Sun. CHAPTER XI. JUPITER. JUPITER is the largest planet in the Solar System. The Axis of Jupiter, is nearly perpendicular to its orbit, and it has, therefore, no change of seasons. The Orbit of Jupiter, makes an angle of about one degree with the plane of the Ecliptic. Jupiter is remarkable for the Oblateness of its figure, occasioned by its rapid rotation on its axis. What does its disc also exhibit? What are these spots supposed to be? Why? What is the cause of the ruddy color of Mars? What phases does it exhibit? Why is it never horned? What is Jupiter? What seasons has it? ter remarkable? What is its size? What is the position of its axis? The Equatorial diameter of Jupiter is more than 6,000 miles greater than its Polar diameter. The Velocity of the Equatorial parts of Jupiter is about 28,000 miles an hour. The Density of Jupiter, like that of the Sun, is only one fourth that of the Earth, being but little heavier than water. The Disc of Jupiter, when viewed with a telescope, exhibits dusky belts, parallel to each other, and at right angles with its axis. The Belts of Jupiter, are supposed to be the dark body of the planet, seen between clouds in its atmosphere. Jupiter is attended by four Satellites, all of which are larger than the Moon. CHAPTER XII. SATURN. SATURN is the sixth planet from the Sun, and is the largest except Jupiter. It is 1,000 times as large as the Earth. The Axis of Saturn inclines 28 degrees towards the plane of its orbit. How much does its equatorial diameter exceed its polar? What is the velocity of its equatorial parts? What is its density? What does its disc exhibit? What are the belts supposed to be? By what is Jupiter attended? What is Saturn? What is its size? What is the inclination of its axis? Its Seasons are, therefore, similar to those of the Earth, but about thirty times as long. The figure of Saturn is remarkable for being flattened at the Equator as well as at the Poles, and presents the appearance of an irregular square. The Density of Saturn is about one tenth as great as that of the Earth, being as light as cork. Saturn is encompassed by two large Rings of solid matter. These Rings are situated in the plane of its equator. The following are their dimensions: Breadth of inner ring, 17,000 miles. Interval between this and outer ring, 1,800 miles. Distance from the planet to the inner ring, 19,000 miles. The thickness of the rings, is supposed to be 100 miles. They are proved to be opaque, by their casting a shadow on the planet, and receiving the shadow of the planet. They revolve on an axis, in the same time as the planet. The Disc of Saturn exhibits belts similar to those of Jupiter. Saturn is attended by eight Satellites. What seasons has it? How is its figure remarkable? What is its density? By what is Saturn encompassed? How are the rings situated? Recite their dimensions? What is the thickness of the rings? How are they known to be opaque? In what time do they revolve? What does the disc of Saturn exhibit? By how many satellites is Saturn attended? CHAPTER XIII. URANUS OR HERSCHEL. URANUS is the seventh planet in the Solar System. It is supposed to be attended by six Satellites; but only three of these are positively known to exist. These Satellites revolve from east to west,-differing, in this respect, from all the other planets. To an inhabitant of Uranus, the Sun appears no larger than Venus does to us,-its apparent diameter being only one minute and a half. CHAPTER XIV. NEPTUNE OR LEVERRIER. NEPTUNE is the most distant planet known in the Solar System. It was first observed, in 1846, by Dr. Galle, of Berlin. The position of this planet was very nearly ascertained by Leverrier, a French mathematician, before its What is Uranus? When, and by whom, was it discovered? What is its magnitude? In what time does it revolve on its axis? By how many satellites is it attended? How do they revolve? How large does the sun appear at Uranus? What is Neptune? When, and by whom, was it discovered? How and by whom was its position previously calculated? |