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

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

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

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 ...

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.

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

Discover the mystery of Planet Nine, the elusive celestial body beyond Neptune. Explore the latest astronomical evidence and ...

The 950-foot hunk of primordial matter is classified as a "potentially hazardous asteroid," but that doesn't mean it has a ...

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

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.