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

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

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system ...

As a result of the International Astronomical Union’s 2006 demotion of Pluto from planet to dwarf planet, our solar system ...

The TNO, which are described as minor planets that orbit the sun at a greater distance than Neptune, were found on the edge ...

For the unversed, "Planet Nine" is a hypothetical planet which is reportedly larger than Earth that is thought to orbit ...

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

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

Scientists' hunt for a mysterious planet at the edge of our solar system might have turned up results. A US-trio appears to ...

The object is about 700 kilometres wide and lies nearly three times farther from Earth than Neptune. Its highly elongated ...

Some astronomers say the strange, clustered orbits of icy rocks beyond Neptune indicate that something big is out there, ...