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

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

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

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

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

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

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 ...

“ Ooh. The “most planet-y” object in the solar system! And how do they infer its existence? With sciencey stuff like this: Well, I’ll believe it when I see it.

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.