Astronomers have discovered four planets that are just a fraction of the mass of Earth orbiting Barnard’s Star, which is 6 ...

The reasoning was that it didn't satisfy one of three newly defined criteria to be a planet. They were: The body must orbit its host star, just as Earth and Jupiter orbit the sun. It is large ...

A very rare treat is about to grace Earth's night skies.

After Friday's spectacle, a "planet parade" of this size won't appear in the night sky for several years, experts say.

Some interpretations of the phrase include the planets lining up on the same side of the sun all right next to each other. The planets can never fully line up exactly like you see in pictures ...