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

Pluto, which infamously lost its status as the ninth planet in 2006, is less than four billion miles away from the sun, sitting in the Kuiper Belt - a region in our solar system beyond Neptune ...

The long-theorized Planet 9, which astronomers have speculated could be a Neptune-sized planet that has been lurking on the outer edge of the solar system, could explain the unusual clustering and ...

There have been questions about a mysterious ninth planet in our solar system for nearly a decade. Pluto was unseated as number nine in 2006. Now, a group of international researchers say they may ...

The astronomers observed hot minerals just beginning to solidify – the first specks of planet-forming material, the ...

According to his models, to explain the clustering and movement of other objects in the Kuiper belt, Planet 9 would need an orbit tilted roughly 15 to 10 degrees from the plane of the solar system.