This disadvantage is offset by the fact that when he rises at sunset he can be seen during the whole night, so that you will not only have plenty of time in which to find him, but to observe him as well. Again, Saturn may be seen any clear night during the winter months until the year 1920. Like the Earth, Saturn is believed to have a more or less solid core, but hotter and with layers of gas around him. It is the sixth planet from the Sun, and with his beautiful rings, which are formed of millions of little pieces—each a moon in itself—and with his ten large moons, when seen through a telescope he is far and away the mightiest sight in the whole sky at night. He and his wonderful rings are shown in Fig. 57. Saturn is 886 millions of miles from the Sun. His diameter is 73,000 miles. His day is 10 of our hours long. His year is 29 of our years long. =Seeing Uranus.=—If you have sharp eyes and will look for _Uranus_ in the spring and summer months, you should be able to see him. He has a pale green color, and on a clear moonless night is visible to a good eye. [Illustration: FIG. 58.—URANUS.] [Illustration: FIG. 59.—NEPTUNE.] Uranus is the planet star from the Sun and before Herschel discovered him with his homemade telescope astronomers frequently mistook him for a fixed star. As seen through a large telescope Uranus shows some indistinct markings. Uranus is 1,780 millions of miles from the Sun. 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. [Illustration: 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. [Illustration: FIG. 61.—TOP VIEW OF SOLAR SYSTEM.]