Planet Nine is a hypothetical large planet in the far outer Solar System, the gravitational effects of which would explain the improbable orbital configuration of a group of trans-Neptunian objects (TNOs) that orbit mostly beyond the Kuiper belt.

The search for Planet Nine yields an important realization: the planet is responsible for the tilt of our sun!

Professor Mike Brown, assistant professor Konstantin Batygin, and graduate student Elizabeth Bailey take questions on their work during the 48th meeting of American Astronomical Society’s Division for Planetary Sciences annual meeting in Pasadena on October 18, 2016.