A recent study introduces a potential new candidate, dubbed Planet Y, inferred from the tilted orbits of distant objects in the Kuiper Belt.

Amir Siraj and team propose Planet Y, a possible unseen planet influencing Kuiper Belt object orbits. Vera C. Rubin ...

Astronomers have found new evidence, revealing the existence of an unseen and mysterious planet that could be hidden in the ...

Astronomers have discovered fresh evidence suggesting the possible existence of an unseen planet in the far reaches of our ...

A new study suggests yet another theory for a possible extra planet in our solar system, likely of a size between Mercury and ...

In the 30 years since the discovery of 51 Pegasi b, more than 6,000 planets outside our Solar System have been catalogued.

Discover the 9 rarest moons in the solar system, from Saturn’s Titan to Neptune’s Triton. Learn about their unique phases, ...

Two recent studies used seismic data from NASA’s retired InSight mission to shed light on what lies beneath Mars’ surface and what it means for the planet’s history The spacecraft will map the ...

Space scientists look back on 30 years of exoplanet discoveries — from rows of massive ‘super-Earths‘ to worlds with ...

Our solar system is a smashing success. A new study suggests that from its earliest period—even before the last of its ...

Ariel, one of Uranus' icy moons, may once have concealed a vast ocean more than 100 miles (170 kilometers) deep beneath its ...