For the first time since Pluto was demoted, the idea of a true ninth planet is edging from speculation toward something ...

Far beyond Neptune, something heavy appears to be tugging on the outer solar system, bending the paths of distant icy worlds ...

Scientists think there may be a ninth planet hiding in the distant reaches of the solar system — and a new telescope could finally prove its existence. | Credit: Nicholas Forder for Live Science Deep ...

NASA's New Horizons spacecraft captured this high-resolution enhanced color view of Pluto that is inserted beneath the Short Wave logo. The image combines blue, red and infrared images taken by the ...

Earlier this year scientists presented evidence for Planet Nine, a Neptune-mass planet in an elliptical orbit 10 times farther from our Sun than Pluto. Since then theorists have puzzled over how this ...

Planet Y is the latest in a series of hypothetical solar system planets that scientists have proposed in recent years, all with slightly different characteristics but collectively believed to be ...

There has been a lot of back and forth about the existence of a mysterious ninth planet, often referred to as "Planet Nine" or even "Planet X." Now, though, researchers say there is likely at least a ...

Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit ...

LONDON — The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper's authors have ...