Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

Add Yahoo as a preferred source to see more of our stories on Google. In our solar system, Earth is one of but eight planets – nine, if you really want to count Pluto – and the only one remotely ...

The decades since scientists confirmed the first planet around another star have been rich in discovery, but it’s rare to see ...

Astronomers typically describe the cosmos with numbers that are, well, astronomical. They measure distances within our galaxy ...

Add Yahoo as a preferred source to see more of our stories on Google. Digital art of distant planet - Dottedhippo/Getty Images On August 24, 2006, our solar system lost a planet. It wasn't by ...

Surprise, it's twins.

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 dubbed ...

Planetary scientists have long debated where the material that formed Earth comes from. Despite its location in the inner ...

Earth is the planet we have the best opportunity to understand in detail—helping us see how other rocky planets behave, even ...