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Planetary Science

Why are inner planets more dense than the outer planets?

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May 15, 2012 11:38AM

Early on in the solar systems formation, rock and metals condensed out at the higher temperatures closer to the sun, forming the terrestrial or rocky inner planets, while gas and water tended to condense further out, forming the gas giant planets.

Although the gas giants are larger than the inner planets, they are mainly made of Helium and Hydrogen gas, while the inner planets are mainly made from more dense materials such as rock.