The Solar System is a vast and mysterious realm, filled with planets, moons, asteroids, and icy bodies waiting to be ...

Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the ...

Observations of the potential Planet Nine are extremely difficult, as it's so far out in the Solar System that it would reflect only the tiniest amount of sunlight. Predictions estimate that the ...

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 ...

Once the quirky underdog of our solar system, Pluto held planetary status until 2006, when it got a cosmic demotion that still stings space fans. Discovered in 1930, Pluto was the ninth planet for ...

A recent research paper suggests that a planet may exist far beyond Neptune — less than 20 years after the previous ninth planet, Pluto, was demoted. That research paper, accepted last month for ...

Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

But are these really "planets," or was Pluto merely the first discovery of an entirely new class of objects? In 2006, the International Astronomical Union, the gatekeepers of astronomical nomenclature ...

The TNO is potentially large enough to qualify as a dwarf planet, the same category as the much more well-known Pluto. The new object is one of the most distant visible objects in our solar system ...

For now, the outer reaches of our 4.6 billion-year-old solar system continue to be shrouded in mystery, with the classification of objects changing as scientists gain a new understanding of them ...