New discoveries of objects in the Kuiper Belt have also presented challenges for the Planet Nine theory. The latest is known ...

The Oort Cloud is a vast, icy shell that surrounds the solar system, marking the farthest reaches of our cosmic neighborhood. Though we have yet to directly observe its objects, the Oort Cloud is ...

A curious, icy and distant object has just been discovered far beyond Pluto. Nicknamed Ammonite, it intrigues astronomers ...

Just the third-ever confirmed interstellar object has been detected in our solar system. Here's what we know. (Spoiler: It's ...

The celestial body's unusual orbit “implies that something extraordinary occurred" in the early days of the solar system—and ...

Astronomers have discovered a "fossil" world lying in the outskirts of the solar system, according to new research.

The largest interstellar comet discovered could be an alien technology. The newly found Manhattan-sized object, named ...

In the dark, icy outskirts of our solar system—far beyond Neptune's orbit—astronomers have discovered a cosmic oddball that ...

A mysterious object the size of Manhattan is blazing through our solar system, and its origins remain a puzzle to the world's ...