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 ...

A newly identified dwarf planet, named 2017 OF201, has been discovered in the distant outer reaches of the solar system.

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

Our moon is a particularly unusual example of moons when it comes to planetary bodies. Though many other planets in the solar ...

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, ...

Their telescopes, on the ground and in space, tend to focus on planets much larger than Earth, in part because they're easier ...

The lone planet confirmed to be in the system is squeezed in between the two, orbiting at a distance similar to Earth's ...

An international team of astronomers claim to have discovered a 'super-Earth' that's bigger than our own blue planet but smaller than Neptune. A new paper, published in the journal, Science has ...

Astronomers have discovered that the Jupiter, the largest planet in our Solar System, was once so big that it could have held ...