A giant planet two to four times the mass of Jupiter has been hiding in one of the most studied star systems in astronomy.

More than a 150 years ago, before Neptune was ever sighted in the night sky, French mathematician Urbain Le Verrier predicted the planet’s existence based on small deviations in the motion of Uranus.

Forbes contributors publish independent expert analyses and insights. An award-winning reporter writing about stargazing and the night sky. Is there an unseen planet — a "planet X" or "Planet Nine" — ...

Add Yahoo as a preferred source to see more of our stories on Google. An illustration showing Planet Nine, a hypothetical, undiscovered planet in our solar system. New research now suggests the ...

Far beyond Neptune, strange orbital patterns suggest the Solar System may still contain a massive unseen planet. Planet 9 ...

Add Yahoo as a preferred source to see more of our stories on Google. A newly discovered warp in the outer Solar System may have been created by a small, rocky world, much closer to the Sun than the ...

The planets are coming! The planets are coming! Only months after announcing the possibility of a 'Planet X' 10 times Earth's mass orbiting 250 times Earth's distance from the sun, a team of Spanish ...

A team of astronomers is proposing that huge spiral patterns seen around some newborn stars, merely a few million years old (about one percent our sun’s age), may be evidence for the presence of giant ...