Pluto's days, though they drag on a bit at around 153 hours, are nothing compared to its years. Pluto's orbit takes 248 Earth ...

Around the bright star Fomalhaut, astronomers spotted glowing clouds of debris left behind by colossal collisions between ...

In a span of 30 years — from the first moon rockets in 1959 to the Voyager 2 flyby of Neptune in 1989 — NASA spacecraft introduced the world to close-up views of the bodies in our solar system.

For the first time since Pluto was demoted, the idea of a true ninth planet is edging from speculation toward something ...

Legend has it that somewhere beyond Neptune and Pluto, there is a ninth planet, with a mass that is five times greater than Earth's. Planet Nine, also known by its more ominous name of Planet X, is ...

(CNN) — The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have ...