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 ...

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

The celestial body's unusual orbit “implies that something extraordinary occurred" in the early days of the solar system—and ...

Astronomers have discovered a new member of a rare and mysterious class of solar system objects known as sednoids - a subset of extreme trans-Neptunian objects (ETNOs) with exceptionally distant, ...

“Planet Nine” is speculated to be a super-Earth—a planet about five to 15 times larger than Earth—that was first theorized in 2016.

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.

Nicknamed "Planet Nine," the real-life Planet X appears to have the mass of 10 Earths and is 20 times farther from the sun than Neptune. Skip to main content. Open menu Close menu.

Planet Nine could be responsible for the tilt of the planets in our solar system; the plane of the planet's orbit is tilted about 6 degrees compared to the Sun's equator; ...

“Planet Nine” could explain the seemingly puzzling orbits traced by two of the distant worlds, known as Sedna and 2012 VP113 (which has been nicknamed “Planet Biden” in homage to a ...

Astronomers hunting for Planet Nine have found some 50 new objects lying beyond the orbit of Neptune – including a few that may help them track down this elusive, distant world.

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 ...

If Planet Nine is real, it wouldn’t be the first planet discovered from the force it exerts on other objects. In 1846, scientists knew another world must be out there due to the anomalies found ...