An alternate explanation that fits the evidence is that Vesta was once part of a planet – but which planet that might been ...

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

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 ...

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

Astronomer Eliza Kempton said that she had waited her "entire career" to peer into an atmosphere from this mysterious class of planets.

Earth has four seasons, but do other planets in our solar system also have hot summer days and cold winter nights?

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

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

Pluto was discovered in 1930 in Arizona, but in 2006 scientists decided to cut Pluto from the planetary line up. Here is why ...

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