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

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

There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as ...

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

At a frigid -125 degrees Fahrenheit (-87 degrees Celsius), WD 1856+534 b is the coldest planet ever directly observed, surpassing the previous record-holder, Epsilon Indi Ab, which stands at around 35 ...

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

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

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

Astronomers searching for a ninth planet in our solar system say they've found a "good" candidate far beyond Neptune, ...

Earth" planet was discovered by researchers. It is not believed these planets are more common than previously thought.