In this topic you will learn about the planets farthest from the Sun.

The outer planets are the five planets farthest from the Sun. The fifth planet from the Sun, and the largest planet in the solar system, is the giant planet Jupiter. Jupiter's volume is 1,500 times greater than Earth's.

Jupiter is made up mostly of gases. It has a thick, cloudy atmosphere that hides its surface. The top of the atmosphere is very cold. Inside, Jupiter is hotter than the surface of the Sun. A photograph of Jupiter from space shows colorful bands of gases. One of Jupiter's special features is the Great Red Spot. Jupiter has at least 16 moons.

Saturn is the second-largest planet in the solar system. Like Jupiter, Saturn is made up mostly of gases. Saturn has 18 known moons. Saturn is known for its beautiful rings. It has thousands of them. These rings are made up of pieces of ice and rock of different sizes.

Uranus is surrounded by a bluish fog. Uranus is so far away it is difficult to see, even with a telescope. Uranus is made up mostly of gases. It has at least 17 moons. Telescopes and photographs show that Uranus has at least 10 rings.

The eighth planet from the Sun is Neptune. It has eight moons. Neptune's gases give it a blue-green color. Like Uranus, Neptune has a cold upper atmosphere and a hot center.

Pluto is the farthest planet from the Sun. It is also the smallest planet in the solar system. Pluto is made up of rocky materials and frozen gases. Little is known about Pluto because it is so far away.

Asteroids and comets are also part of the solar system. An asteroid is a small chunk of rock or metal that orbits the Sun. Asteroids come in a variety of shapes and sizes. Most asteroids are found between Mars and Jupiter. This part of space is called the asteroid belt. A comet is a body of ice and rock that moves around the Sun in long, narrow orbits. When a comet passes close to the Sun, it becomes very warm. Some of the ice changes to gases. The solar wind pushes the gases out into a long tail. When a comet passes close to Earth, you can see its tail.