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 ...

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

Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about ...

An object seen to have moved in the time between when it was imaged by the IRAS and AKARI surveys in 1983 and 2006 ...

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.

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

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

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