If the object really is Planet Nine, it would be larger than Neptune and exist 700 times further from the sun than Earth.

Astronomers have detected a promising sign of a ninth planet lurking at the the farthest reaches of the Solar System.

"It's like trying to spot a fish by looking for ripples in a pond, rather than trying to see the fish itself." ...

The solar system consists of our star, the sun, and everything bound to it by gravity: the planets Mercury, Venus, Earth, ...

Mar. 17, 2025 — A combination of cosmic processes shapes the formation of one of the most common types of planets outside of our solar system, according to a new ... Webb Telescope Captures Its ...

An international team including astronomers from the Center for Astrophysics | Harvard & Smithsonian (CfA) has announced the ...