If the object really is Planet Nine, it would be larger than Neptune and exist 700 times further from the sun than Earth.

Scientists examined infrared space surveys to narrow down candidates for Planet 9. Planet 9 would be so far from the Sun that ...

For years, astronomers have toyed with the idea that the Sun hides an extra planet so distant and dim that even the best ...

Discovered in 1930, Pluto was long considered our Solar System's ninth planet, but was unseated in 2006 after the discovery ...

Pluto was discovered in 1930 in Arizona, but in 2006 scientists decided to cut Pluto from the planetary line up. Here is why ...

Astronomers from MIT have uncovered a dramatic celestial spectacle: a Mercury-sized exoplanet that is rapidly disintegrating ...

The planet is estimated to be 2 to 4 times the radius, and about ten times the mass of the Earth. | Credit: Mark Garlick/Science Photo Library/Getty Images The best candidate yet for the elusive ...