SC.5.E.5.2 Inner and Outer Planets

SC.5.E.5.2 Recognize the major common characteristics of all planets and compare/contrast the properties of the inner and outer planets.

What Objects Make Up the Solar System?

A solar system is made up of a star and all the objects which orbit the star. Our solar system has one star, the Sun. Stars are very large objects in space which produce energy. Some of the energy produced by stars is light. You can see the light from the star at the center of our solar system every day.

There are eight planets in our solar system. Planets are large objects in space that do not produce their own light. Planets reflect the light if the star they orbit. There are four inner planets: Mercury, Venus, Earth, and Mars. There are four outer planets: Jupiter, Saturn, Uranus, and Neptune. Between the inner planets and the outer planets is the asteroid belt. Asteroids are irregularly shaped objects made mostly of rock.

The four inner planets are much smaller than the four outer planets. The inner planets are made mostly of rock. Venus, Earth, and Mars have atmospheres of gas. The four outer planets are the gas and ice giants. Jupiter and Saturn are very large planets are made mostly of gas. Uranus and Neptune were once thought to be gas giants, but they have recently been found to be ice planets with atmospheres of gas. Uranus and Neptune are known as ice giants.

Some planets have moons. Moons are objects that are smaller than the planet they orbit. The Earth has one moon. Mars has two. Jupiter, the largest planet in the solar system, has eighty moons. Saturn, Uranus, and Neptune also have many moons.

None of the inner planets have rings. Saturn, one of the outer planets, has rings that are easily visible through a telescope. Jupiter, Uranus, and Neptune all have rings, but they are not easily seen. All the outer planets have rings.