For decades, our solar system was thought to have nine planets, with Pluto considered the smallest and farthest. But in 2006, Pluto was officially reclassified as a dwarf planet by the International ...

A powerful new observatory is the best hope yet for finding the elusive Planet 9, a large planet that some scientists say is hidden in our solar... If Planet Nine is out there, this telescope might ...

Astronomers used a telescope in Hawaii to find a new object on the outer edges of our solar system, helping to fuel evidence of a long-standing theory about Planet Nine, or Planet X. For years, ...

For nearly a decade, scientists have been on the hunt for Planet Nine – a hypothetical celestial object on the edge of our Solar System. Now, astronomers claim to have discovered this ninth planet ...

What just happened? A newly identified object spotted in two infrared sky surveys may be the most substantial evidence for the elusive Planet Nine – a potential Neptune-sized world orbiting hundreds ...

When I was a kid, there were nine planets. Now we know of thousands! But that includes exoplanets, alien worlds that orbit alien suns. Only eight planets call our solar system home. Or there might ...

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, waiting to ...