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

Astronomers have picked up evidence of an Earth-sized world, distinct from the previously hypothesised Planet Nine and Planet ...

Recent research suggests a warp in the orbital plane of Trans-Neptunian Objects (TNOs) between 80 and 400 AU, hinting at the ...

Planet Nine was previously suggested as a possible explanation for distant orbital clustering. It was thought to be ten times Earth’s mass, orbiting far beyond Neptune.

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

The Solar System does not have a clear border. The influence of the Sun in certain domains is small enough for the Voyager ...

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 ...

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.

"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 ...