Planet Nine Planet Nine Planet Nine is a hypothetical planet in the outer region of the Solar System. Its gravity could explain the unlikely clustering of orbits for a group of extreme trans-Neptunian objects (eTNOs) that orbit beyond Neptune with average distances greater than 250 AU. These eTNOs tend to have their points of closest approach to the Sun clustered in one direction, and many of their orbits have a similar tilt. This evidence suggests that the gravity from a large undiscovered object is influencing the orbits of the most distant known Solar System objects. This undiscovered super-Earth-sized planet would have an
Max Planck Institute for Solar System Research Max Planck Institute for Solar System Research The Max Planck Institute for Solar System Research (abbreviation: MPS; ) is a research institute in astronomy and astrophysics located in Göttingen, Germany, where it relocated in February 2014 from the nearby village of Lindau. The exploration of the solar system is the central theme for research done at this institute. MPS is a part of the Max Planck Society, which operates 80 research facilities in Germany. Over the last five years, members of the Institute have each year published about 270 articles in international journals and books and given 360 conference presentations.