Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory about the possibility of a giant ninth planet. The dwarf planet's existence ...

Add Yahoo as a preferred source to see more of our stories on Google. (Ianm35/iStock/Getty Images Plus) The Solar System is one of the comforting constants of human existence. No matter what else we ...

The number of confirmed planets outside of our solar system—known as exoplanets—has risen to 6,000, NASA has said. There is huge variety across these distant worlds, the space agency says, with ...

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 ...

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 ...