Astronomers propose a new hypothetical planet, Planet Y, beyond Neptune, based on observed orbital anomalies in the Kuiper ...

A study suggests an Earth-sized planet, dubbed Planet Y, may exist beyond Neptune, affecting the orbits of icy objects in the ...

A mysterious new world may be hiding in the outer reaches of our solar system. According to arecent study published on arXiv ...

A new study suggests the existence of Planet Y. This hidden planet may be affecting the Kuiper Belt. The gravity of Planet Y ...

A recent study hints at a previously unknown Earth-sized planet, dubbed Planet Y, potentially influencing gravitational distortions in the outer solar system.

Searching for Planet X, Y and Z Space.com: Astronomers haven't yet found the fabled Planet X, but they are increasingly confident that such a 10th planet exists — in fact, several of them.

It’s “the most planet-y of the planets in the whole solar system,” said Brown, who is famous for helping demote Pluto to a dwarf planet. Related: Exoplanet hunters made key finds in 2015 ...

"Planet X" might actually exist — and so might "Planet Y." At least two planets larger than Earth likely lurk in the dark depths of space far beyond Pluto, just waiting to be discovered, a new ...

A huge planet might be sitting at the edge of our solar system without ever being seen. The world — which could be about ten times as massive as Earth — would be large enough to become the ...

“Planet Nine” could explain the seemingly puzzling orbits traced by two of the distant worlds, known as Sedna and 2012 VP113 (which has been nicknamed “Planet Biden” in homage to a ...