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 ...

According to NASA, planets always appear in a line in the sky. The planets rotate around the sun basically in a disc-shaped ...

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 ...

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

Whenever planets are visible in the night sky, they always appear roughly along the same line. This path, known as the ...

Astrophysicists have once again enriched our knowledge of the cosmos with a new discovery: two small planets orbiting ...

Mercury is joining Venus, Mars, Jupiter, Saturn, Uranus, and Neptune for a seven-planet parade. It's a stargazer's paradise.