The TNO orbits in a plane that’s tilted 110 degrees to the plane of the solar system. What’s more, it swings around the sun backwards unlike most of the other objects in the solar system. With this in mind, the team that discovered the TNO nicknamed it “Niku” after the Chinese adjective for rebellious.
To grasp how truly rebellious it is, remember that a flat plane is the signature of a planetary system, as a star-forming gas cloud creates a flat disk of dust and gas around it. “Angular momentum forces everything to have that one spin direction all the same way,” says Bannister. “It’s the same thing with a spinning top, every particle is spinning the same direction.”
That means anything that doesn’t orbit within the plane of the solar system or spins in the opposite direction must have been knocked off course by something else. “It suggests that there’s more going on in the outer solar system than we’re fully aware of,” saysMatthew Holmanat the Harvard-Smithsonian Center for Astrophysics, part of the team that discovered Niku using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS 1) on Haleakala, Maui.
And it’s the unknown that excites astronomers. “Whenever you have some feature that you can’t explain in the outer solar system, it’s immensely exciting because it’s in some sense foreshadowing a new development,” saysKonstantin Batyginat the California Institute of Technology.