Saturn has 83 known moons, the most of any planet in our Solar System. This size comparison video from MetaBallStudios lines them all up, with London as the background. The same YouTuber recently ...

Gareth Dorrian 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 ...

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights. The size of the solar system is defined by the volume ...

Is there another planet at the edge of our solar system? (Getty Images/Nasa) A huge planet that has never been seen by astronomers could be lurking, almost invisibly, at the dark edges of our solar ...

CAPE CANAVERAL, Fla. — Astronomers have discovered a rare in-sync solar system with six planets moving like a grand cosmic orchestra, untouched by outside forces since their birth billions of years ...