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

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

A newly found icy object, Ammonite, may be a 4-billion-year-old fossil from the Solar System’s edge—and it’s casting doubt on ...

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.

For years, scientists have been scanning the icy outskirts of our Solar System for an unknown massive planet. The disturbances observed in the orbits of Kuiper belt objects suggest the presence ...

Astronomers have hoped for the existence of Planet Nine for years. Things were looking promising, but this discovery might ...

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.

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." ...

But even if it doesn't spot Planet 9 directly, the Rubin Observatory might find some more minor planets, ones whose orbits might be affected by Planet 9. And that could provide additional evidence ...