OF201 spends only 1% of its orbital time close enough to us to be detectable. The presence of this single object suggests ...

OF201 is incredibly lightweight on a cosmic scale. Scientists estimate its mass is about 20,000 times less than Earth's and ...

A potential new dwarf planet has been discovered in the outer reaches of the solar system, and its existence poses the ...

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

Scientists have discovered a colossal object approximately 435 miles wide in the frigid outer reaches of our solar system, ...

Almost 20 years after Pluto was infamously downgraded from its status as a planet, scientists now believe they have ...

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

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

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

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

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