The status of Pluto not withstanding, our solar system has 8 planets, but one astronomer believes we used to have a ninth that was eaten by the sun.

The solar system lost its ninth planet back when Pluto was demoted to a dwarf planet, but research might indicate that there ...

Planet 9 is the hypothetical ninth planet in our Solar System. Has it finally been found using IRAS and AKARI mission data?

Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the discovery of Pluto in the 1930s. Labeled as planet X, prominent astronomers ...

Add Yahoo as a preferred source to see more of our stories on Google. Digital art of distant planet - Dottedhippo/Getty Images On August 24, 2006, our solar system lost a planet. It wasn't by ...

Is there a massive undiscovered planet on the outer reaches of the Solar System? The idea has been around since before the discovery of Pluto in the 1930s. Labelled as planet X, prominent astronomers ...