Learn how a possible ninth planet, the theoretical Planet X, could have acquired its wide orbit in the outer Solar System - a ...

There’s a new object in the distant reaches of our solar system, and it might just offer clues to a long-standing cosmic ...

For decades, our solar system was thought to have nine planets, with Pluto considered the smallest and farthest. But in 2006, ...

In the cold, dark outskirts of planetary systems far beyond the reach of the known planets, mysterious gas giants and ...

Astronomers find evidence of a possible ninth planet beyond Neptune, reigniting the debate about the formation of the Solar ...

A team of astronomers believe they may have discovered a new dwarf planet—just like Pluto—on the edge of our solar system.

Today, it’s believed that Jupiter and Saturn, the largest planets, were the first to fully form, both within a few million ...

A new dwarf planet, discovered beyond Neptune and described as Pluto's 'cousin,' could void the hypothesis of a Planet X in ...

Astronomers have just discovered a new celestial body in our solar system that could challenge major space theory. 2017 OF201 ...

Astronomers have announced the discovery of a new dwarf planet in our solar system, named 2017 OF201. Located far beyond ...

Following the much-ballyhooed “planet parade” this winter, the planets have been gradually dipping below the horizon, ...

Christopher Palma does not work for ... the first thing to form in our solar system. This happened about 4½ billion years ago. Then the planets began to emerge, as the billions of particles ...