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

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

Scientists have identified an object about 435 miles (700 km) wide inhabiting the frigid outer reaches of our solar system that might qualify as a dwarf planet, spotting it as it travels on a highly ...

Curious Kids is a series for children of all ages ... icy bodies into the Kuiper Belt , a place in the outer solar system ...

Brown’s discovery of Eris, an icy world in the Kuiper Belt beyond Pluto, led to the reclassification of Pluto as a dwarf planet. He has been dubbed the “Pluto Killer.” Pilot project launched ...

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

A small team led by Sihao Cheng, Martin A. and Helen Chooljian Member in the Institute for Advanced Study's School of Natural ...

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.

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

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected]. Are planets in the solar system that are ...

The two space surveys, conducted 23 years apart, could show how a secret planet orbits. Since the demotion of Pluto to dwarf planet, there’s been a ninth-planet-shaped hole in the hearts of many ...

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