Are planets in the solar system that are closer to the Sun older than the ones further away? – Gavriel, age 10, Paducah, Kentucky A cloud of collapsing gas created our Sun, the first thing to form in ...

The Sun's formation caused temperature differences in the surrounding disk of gas and dust. Inner, hotter regions formed rocky planets from less volatile elements. Outer, colder regions allowed ...

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The giant planets weren't always where we find them today. Jupiter, Saturn, Uranus and Neptune formed in a more compact ...