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

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.

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

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

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

The Kosmos 482 probe crashed to Earth today (May 10) after circling our planet for more than five decades. Reentry occurred ...

For nearly a decade, scientists have been on the hunt for Planet Nine – a hypothetical celestial object on the edge of our Solar System. Now, astronomers claim to have discovered this ninth ...

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