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.

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

With an atmosphere, by mass, of primarily hydrogen (76 per cent) and helium (24 per cent), and by volume of 89 per cent ...

In a thrilling development that challenges long-held assumptions about the outer reaches of our solar system, astronomers ...

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