Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the discovery of Pluto in the 1930s. Labeled as planet X, prominent astronomers ...

For over a century, astronomers have wondered if there’s an extra planet in our Solar System that we haven’t been able to detect yet. It seems like we get another “Planet Nine” candidate — formerly ...

A leading scientist has told Newsweek about new evidence supporting the existence of a secret ninth planet lurking at the edge of our solar system. This hypothetical extra planet, often referred to as ...

It’s been nearly 2 centuries since a planet was discovered in the solar system. But now scientists think they’ve uncovered ...

Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

For over a century, researchers have been puzzled by strange gravitational forces seemingly pulling on the orbits of Neptune and Uranus in the distant reaches of our solar system. While some have ...

The apparent brightness of celestial objects, rather than their proximity, is the primary factor determining observability. Andromeda Galaxy, despite its vast distance, appears significantly brighter ...

A mysterious new world may be hiding in the outer reaches of our solar system. According to arecent study published on arXiv by Amir Siraj of Princeton University and colleagues, a previously unknown ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it. Some astronomers ...

A possible cousin of Pluto seems to be circling the far reaches of the solar system. The dwarf planet candidate 2017 OF201 travels in a superwide orbit, with the sun relatively near one end of its ...