- His diameter is 32,000 miles.
- His day is thought to be 11 hours long.
- His year is 84 of our years long.
Neptune.—Neptune is so far away from the Sun he cannot be seen with the naked eye, but he can be easily seen with a good opera glass. He is attended by one moon. He is simply a disk of light when seen through a big telescope, as shown in [Fig. 59].
Neptune is 2,790 millions of miles from the Sun.
- His diameter is 36,000 miles.
- His day is unknown.
- His year is 165 of our years long.
The Asteroids.—The Asteroids are a group of small planets moving around the Sun in orbits between the Earth and Mars and, hence, at times these little bodies come very close to us. The group occupies a place in the sky where we should expect to find a single large planet.
Fig. 60.—Marbles on Top of Table.
But when the planets were made, Jupiter, with his great bulk pulled the soft pieces apart of which a planet would have been formed, and instead of one planet of respectable size there are hundreds of little planets ranging anywhere from 10 miles to 500 miles in diameter.
One of these small planets is called Vesta, and although she is only 240 miles in diameter she may be seen on certain occasions with the naked eye.
Positions of the Planets Round the Sun.—It was mentioned in the beginning of this chapter that all of the planets lay not far from one plane, and that the Sun’s equator is nearly in this plane. Now let us see just what this means.