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Why do the outer planets have more moons than the inner planets?

Deanna Rostic, St. Catharines, Ontario, Canada
Moons
The giant planets formed in a drastically different environment from the terrestrial planets. It was much colder in the outer solar system, so water was ice, but in the region near where Earth formed, water turned to steam. Water is one of the most common chemical compounds, and its ice form accretes much more easily. This encouraged the outer planets to grow massive.

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