History of Oceania

Why is Neptune an outer planet?

Neptune is an outer planet because it is not a terrestrial planet. Terrestrial planets, such as Earth and Mars, are rocky and have a solid surface. Outer planets, such as Neptune and Jupiter, are gas giants and do not have a solid surface. They are composed mostly of hydrogen and helium and are very large and have a lot of mass. Neptune is the farthest planet from the Sun, and is approximately 30 times farther from the Sun than Earth.