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 ...

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights. Maggie Lieu, Research Fellow, School of Physics and ...

This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated. NEW ORLEANS (WGNO) — Mercury, Venus, Mars, ...