Far beyond the bright planets, in the dim outskirts of the Solar System, astronomers keep stumbling on objects that refuse to ...

Astronomers used a telescope in Hawaii to find a new object on the outer edges of our solar system, helping to fuel evidence of a long-standing theory about Planet Nine, or Planet X. For years, ...

Planets smaller than Neptune but larger than Earth, with atmospheres saturated with water vapor due to extreme temperatures, are puzzling astronomers. Scientists have developed an improved model to ...