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

A 9th planet in our solar system might be found — and no, it’s not Pluto - Is there another planet out there? Researchers say ...

Researchers have found a candidate for the hypothetical Planet Nine, which could be an undiscovered giant planet way out in ...

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

The solar system is our cosmic neighborhood ... Neptune and then the possible Planet Nine. It's a dynamic system shaped by gravity and time, and while we've learned a lot, it still holds plenty ...

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

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

A ninth planet the size of Neptune may be hidden in the far reaches of the solar system, but the evidence has left some experts skeptical.

Astronomers may have found a candidate for Planet Nine. This planet is beyond Neptune. The finding could be the first ...

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

The presence of another planet in the solar system could explain the odd movements of some of the bodies in the Kuiper Belt.