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 edge of our solar system.

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 ...

In 2006, the International Astronomical Union stopped classifying Pluto as our solar system’s ninth planet and demoted its ...

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 ...

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

Discovery of a possible dwarf planet suggests our cosmic backyard holds many more secrets to uncover It is an evocative idea ...

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

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