Known as Planet Nine or Planet X, it is a hypothetical planet that has long been rumoured to exist in the outer solar system. Although "several claims to have found an extra planet have been made ...

"This type of survey is going to allow us to try and put a limit for how bright we think Planet Nine might be." The survey will map the sky in the Southern Hemisphere for 10 years, and because it ...

For the first time, scientists have developed a 3D map of an atmosphere belonging to a planet outside our solar system. Attached to a particularly mysterious alien world, the newly charted ...

After Friday's spectacle, a "planet parade" of this size won't appear in the night sky for several years, experts say.