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

Discover the order of planets in the solar system. From Mercury to Neptune, explore our solar system and learn more about our cosmic home. The solar system is our cosmic neighborhood, made up of ...

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

Astronomers have detected a promising sign of a ninth planet lurking at the the farthest reaches of the Solar System.

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.

A powerful new observatory is the best hope yet for finding the elusive Planet 9, a large planet that some scientists say is ...

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