The curious minds at What If explore what would happen if Planet X entered our solar system.

Scientists may have discovered a dwarf planet far beyond Neptune — an unearthing that may disprove a longstanding theory about the possibility of a giant ninth planet. The dwarf planet's existence ...

Astronomers used a telescope in Hawaii to find a new object on the outer edges of our solar system, helping to fuel evidence of a long-standing theory about Planet Nine, or Planet X. For years, ...

After studying thousands of computer simulations of the solar system, researchers at Rice University and the Planetary Science Institute think there’s a 40% chance an elusive “Planet Nine” or “Planet ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it. Some astronomers ...

TUCSON, Ariz. (KVOA) - Astronomers have confirmed a new planet in one of the youngest solar systems ever found, thanks to University of Arizona technology. The system, called WISPIT 2, was first ...

TUCSON, Ariz. (KGUN) — What started as a mysterious red dot in images taken by University of Arizona astronomers has been confirmed as a huge, newly forming planet — and University of Arizona’s ...