The Outer Planets
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A Star Is Born Stars form in cold, dense regions of space called molecular clouds. When the force of gravity pulling in on the cloud is greater than the strength of internal pressure pushing out, the cloud collapses into a protostar. Learn More ->
Sections:

Where do stars form?
Why do stars form?
What slows the cloud collapse?
Nuclear Fusion
Masses of Newborn Stars
How Planets Form The terrestrial planets formed close to the Sun where temperatures were well suited for rock and metal to condense. The jovian planets formed outside what is called the frost line, where temperatures were low enough for ice condensation. Learn more ->
Sections:

Overview
Terrestrial planet formation
Jovian planet formation