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 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 ...

Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the distant solar system. The object, which the researchers have nicknamed Planet Nine, has a ...

"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 ...

“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 ...

With a mass likely to be 5,000 times Pluto's and a gravitational influence that dominates an enormous orbit, Brown says it's "the most planet-y of the planets in the whole Solar System." ...