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

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

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

At the very edge of our solar system, beyond the grasp of Neptune and even past the icy sprawl of Pluto’s domain, a new ...

In the cold, distant reaches of the Solar System, far beyond Pluto, astronomers have just identified what could be a new ...