Mike Brown is convinced that beyond Neptune, at the far reaches of our solar system, there's an unseen giant planet. "This is the 5th largest planet in our solar system, lurking out there ...

They theorized that a potential planet’s long orbit would enable them to see it move across the sky. They found 13 pairs of dots that could be explained by a moving planet that resembled Planet ...

A team of astronomers says it has identified a single, slow-moving infrared object that checks all the right boxes for it being the long-theorized ninth planet lurking beyond Neptune. The hunt for ...

The planet "splashed down" into the star, sending a giant plume of gas into space that gave the star a ring. The James Webb Space Telescope (JWST) has been studying the scene of a dramatic ...

With Pluto having been classed as the ninth planet for many years, the hunt was on for Planet X. With the demotion of Pluto in 2006, the idea of Planet Nine was first proposed in 2016 by ...

Astronomers announced Thursday that they had detected the most promising "hints" of potential life on a planet beyond our solar system, though other scientists expressed skepticism. There has been ...

HANDOUT/University of Cambridge/AFP via Getty Scientists believe they might have discovered evidence of life on a planet 700 trillion miles away from Earth. K2-18b, a planet more than double the ...

Discovered in 1930, Pluto was the ninth planet for over 75 years, orbiting at the chilly fringes of our solar neighborhood. But then scientists at the International Astronomical Union decided ...