The word “planet” came from the ancient Greek words that mean “wandering star.” That makes sense, because for thousands of years, people have watched planets change position in the night sky — unlike ...

Have you ever looked up on a clear night at the stars and noticed that some of them seemed to twinkle or dance? This twinkling is due to the Earth’s atmosphere. When light reaches Earth from a star, ...

Dr Rudi Kuhn does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their ...

The ancient Greeks proved over 2,000 years ago that the Earth was round and figured out how big it was by using simple observations of the Sun. But how do people know this today? When you drop ...