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 ...

Our solar system’s origin story spans billions of years and involves clouds of gas, cosmic collisions, and planetary ...

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

Scientists hunting for the hypothetical Planet Nine have discovered a potential new dwarf planet, 2017 OF201, in the outer ...

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 ...

Learn about the recently discovered trans-Neptunian object that may eventually join Pluto as a dwarf planet, found at the ...

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 ...