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

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

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

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.

What are brown dwarfs? They’re not planets, not quite stars, but fascinating cosmic objects in their own right. Dive into the science of these “failed stars,” their role in the universe, and how they ...

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

The chance of a planet forming in the outer reaches of the solar system - a hypothetical Planet Nine - could be as high as 40 ...

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 ... .</ ...

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 ...

Researchers say they found a curious dot on infrared images taken 23 years apart that seems to be moving in a manner consistent with a large, distant planet.

It saw the discovery of dwarf planet Eris and how those very observations ... of dwarf planets and made a lot of people angry. Still, kids in school now learn that the Solar System is not just ...

In 2005, Eris was discovered. It was considered the largest known dwarf planet in the solar system until a year later when Pluto was downgraded from being a planet. In 2008, tribal violence ...