As it orbits the sun once every 25,000 years, the celestial body 2017 OF201 travels beyond the Kuiper Belt into a region ...

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

Learn about the recently discovered trans-Neptunian object that may eventually join Pluto as a dwarf planet, found 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.

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

Astronomers have announced the discovery of a new dwarf planet in our solar system, named 2017 OF201. Located far beyond ...

A new dwarf planet, discovered beyond Neptune and described as Pluto's 'cousin,' could void the hypothesis of a Planet X in ...

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 ...

Earth has a new neighbor that lives far, far away. Scientists from the Institute for Advanced Study's School of Natural ...