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 ...

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 ...

Seven planets are aligning in the night sky and will be visible Friday, February 28. The alignment, also called a "planet parade," happens when planets' orbits around the sun cause them to appear ...