Stars! Stars! Meet the Planets! The Sun is a medium-size star. All nine of the planets in our solar system orbit the Sun. The Sun has been burning for about 5 billion years. Mercury, the closest planet to the Sun, is only a little larger than the Moon. Its surface is covered with tall mountains and deep craters. Venus is a planet, but it is called the Evening Star because it is usually the first light we see shining in the evening sky. Earth, our home, is the only planet in our solar system that we know supports life. Mars, the red planet, is about half the size of Earth. Mars looks red because it is covered with rust-colored soil. Jupiter is the largest planet in our solar system. It is so big that all of the other planets could fit inside it. Saturn is not very dense and would float in water. Its rings are made of pieces of dust and ice varying from as small as a pea to as large as a car. Uranus spins on its side. The narrow ring around Uranus is made of black ice. Neptune, the blue planet, has winds that blow up to 1,500 miles per hour (2,420 km/h).
