Planet 9
Scientists Are Angry About 'Planet 9' Because of Pluto
Some researchers think that a hypothetical ninth planet exists in the furthest reaches of the Solar System.
Scientists Offer New Idea on Outer Solar System Puzzle
The collective gravity of lots of little objects might add up to a powerful force.
Will This Giant Planet Really Destroy Earth?
The apocalypse, it seems, is upon us again.
NASA Hasn’t Confirmed Existence of Planet 9
But scientists are honing in on its location.
Planet 9 Is Not a Stolen Exoplanet—So What Is It?
Scientists say the possibility a giant hypothetical planet was commandeered by the sun is “almost zero.”
A Mars-Sized Planet at the Edge of the Solar System?
Scientists say an object about the size of Mars is disrupting the orbits of Kuiper Belt objects.