Some of the planets in our Solar System are gigantic. But what if they got even bigger? Let’s go up the planetary size chart ...

Legend has it that somewhere beyond Neptune and Pluto, there is a ninth planet, with a mass that is five times greater than ...

Mike Brown is convinced that beyond Neptune, at the far reaches of our solar system, there's an unseen giant planet. "This is the 5th largest planet in our solar system, lurking out there, waiting to ...

How common are Earth-like planets in the universe? When I started working on supernova explosions, I never imagined that my ...

Earth has the perfect combination of a livable atmosphere and a protective magnetic field that prevents the Sun's harmful radiation and radioactive solar winds from damaging us, allowing us to live on ...

Skywatchers who spotted the Jupiter-Venus conjunction on Aug. 12 are in for a dazzling display in the night sky through the end of August, with a "planet parade" building in the eastern sky, with ...

A visible line of planets has for weeks been the talk of astronomers and hobbyist stargazers who have sought to catch a sight of our solar system's worlds. Online chatter and a frenzy of media ...

A powerful new observatory is the best hope yet for finding the elusive Planet 9, a large planet that some scientists say is hidden in our solar... If Planet Nine is out there, this telescope might ...