When you think of a planet, you probably think of one of the planets in our own solar system, like Earth, Jupiter, or Mars. Most of the exoplanets we’ve discovered have been like those in our solar ...

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

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

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

A passing star has been discovered that could cause chaos in the Solar System, sending Earth flying out of orbit.

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

While astronomers continue to search for the mysterious "ninth planet”, a possible giant hidden in the extremities of the ...

A recent study found that Jupiter was once twice the size that it is now, making it big enough to swallow up 2,000 Earths.

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 ...

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

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 ...