We still don't know for sure if there's a ninth planet in our solar system, but a new discovery could help to prove that ...

A tiny object far beyond Pluto, newly discovered by the Subaru Telescope, could reshape our understanding of the early Solar ...

A stronomers have discovered an incredibly rare non-planetary body lurking on the outer reaches of the Solar System, which ...

"It is possible that a planet once existed in the solar system but was later ejected, causing the unusual orbits we see today ...

Researchers use the Subaru Telescope in Hawaii to find a small object on the outer edge of the Solar System. Nicknamed ...

Planet Nine should appear stationary over the course of a single day but show detectable movement over months.

Planet Nine's composition is probably "most like Neptune," due to its distance from the sun, Brown said. "That would put its diameter at something like two times the width of Earth," he added.

If their calculations serve them correctly, Planet Nine would have a mass that is about 1.5 to 3 times that of Earth, at 500 times the distance between our home and the sun.

Growing up, I was taught that there were nine planets in the solar system. That all changed in 2006, when the International Astronomical Union voted to demote Pluto’s status to that of dwarf planet.

If Planet 9 is on the smaller side, dark, and really far away, he explains, "it's going to be on the edge of Vera Rubin detection, and Vera Rubin may not find it." ...

In October 2017, NASA released a statement saying that Planet Nine may be 20 times further from the Sun than Neptune is, going so far as to say "it is now harder to imagine our solar system ...