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

The small world was found during a search for the hypothetical Planet Nine, and astronomers say the next time it will reach ...

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the ...

Some astronomers say the strange, clustered orbits of icy rocks beyond Neptune indicate that something big is out there, ...

A new dwarf planet discovery in the outer solar system is challenging the long-standing theory of a hidden giant planet ...

A US-based trio hunting this elusive world has stumbled on what appears to be a new dwarf planet in the solar system's outer ...

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

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