Astronomers in the United States have announced the discovery of the "10th planet" to orbit our Sun. The largest object found in our Solar System since Neptune in 1846, it was first seen in 2003 - but ...

Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory ...

All eight of the solar system’s “major” planets appear in this illustration, ... Should it be discovered, whether you want to call it the ninth or 10th or 1,000th planet is up to you.

Over the past decade, researchers have been puzzling through Pluto’s mysteries. Meanwhile, the New Horizons probe heads for interstellar space.

Some may remember that Pluto was once considered our solar system’s ninth planet until it was demoted to dwarf planet in 2006, when scientists began to realize how many planetary bodies exist ...

Rare "in-sync" solar system discovered by scientists 04:12. Astronomers have discovered a rare in-sync solar system with six planets moving like a grand cosmic orchestra, untouched by outside ...

Pluto was reclassified as a dwarf planet in 2006. Our solar system may have a ninth planet after all, researchers say. The possibility that an additional planet may be hidden far into the solar ...