For years, astronomers have searched for evidence of a hidden giant planet at the edge of our solar system. New data suggests Planet 9 may be closer to discovery than ever.

Astronomers continue the search for a massive unseen planet that could reshape our understanding of the solar system.

U.S. astronomers hunting for "Planet Nine" have instead stumbled on what appears to be a new dwarf planet in the solar system's outer reaches.

Planet Nine was estimated to have a temperature range between 53 and 28 K. Only requiring AKARI detection can expand the search to five times fainter objects than a previous survey.

Some experts believe that the solar system's hypothetical ninth planet could be just a few years away from being discovered. If this is the case, how long would it take for humans to send probes ...

New discoveries of objects in the Kuiper Belt have also presented challenges for the Planet Nine theory. The latest is known ...

Now, a team led by astronomer Terry Long Phan of the National Tsing Hua University in Taiwan has delved into the archives of two far-infrared all-sky surveys in search of Planet Nine — and ...

Science Search for 'Planet Nine' Yields Unexpected Discovery Less than 1% of this dwarf planet candidate's orbit is close enough to detect, which means astronomers are lucky to have caught it at all.

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 system.

Some scientists are convinced that beyond Neptune, there's a planet they've yet to see. This so-called "Planet 9" is so far away, it would be a faint object. The stretch of sky researchers would ...

Almost a decade after astronomers proposed the existence of Planet 9, an unseen extra planet in the distant reaches of the solar system, they still haven’t all agreed whether it’s real or not.