Our solar system may have a ninth planet after all, following the declassification of Pluto nearly two decades ago, ...

Astronomers have detected a promising sign of a ninth planet lurking at the the farthest reaches of the Solar System.

A new look through decades-old data has unveiled some of the most compelling evidence yet of a hidden ninth planet in the far ...

The solar system consists of our star, the sun, and everything bound to it by gravity: the planets Mercury, Venus, Earth, ...

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