Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously ...

There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006. Now, a group of international researchers say they may ...

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

LONDON — 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 ...

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 ...

The star system V1298 Tau reveals that many planets begin as large, low-density worlds that slowly shrink and shed their ...