Astronomers have spent more than a century searching for a hidden world beyond Neptune, first called Planet X and now often ...

What is Planet Nine, and where is it? The question has fascinated astronomers for years. Scientists believe a massive ...

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" — ...

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 ...

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 ...

A bright ring of dust circling a young star can look calm from far away. In reality, it may mark one of the messiest moments ...

One of the longest stellar dimming events ever observed was likely caused by the gigantic saucer-like rings of either an unseen brown dwarf or "super-Jupiter" blocking its host star's light, ...

A team of astronomers has achieved a breakthrough in observing planetary formation by directly tracking the rotation of a ...

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 ...