A team of astronomers believes they may have spotted a serious candidate for a ninth planet in our Solar System. This object, ...

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

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

Using two infrared space telescopes and a 23-year gap, scientists may have spotted a mysterious, slow-moving object beyond ...

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

Astronomers have long speculated about an unseen planet lurking in the solar system's outer edge. This hypothetical world, ...

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.

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

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

Researchers say they found a curious dot on infrared images taken 23 years apart that seems to be moving in a manner consistent with a large, distant planet.

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