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 ...

While Mercury is the innermost planet in the Solar System, on average it spends more time closer to Earth than Venus does.

(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.) Curious Kids is a series for children of all ages. If you have a question you’d like ...