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
Outer Planet Flagship Mission Outer Planet Flagship Mission The Outer Planet Flagship Mission is a type of NASA program to research larger size missions to the outer solar system, and some examples of this type of mission are Galileo or Cassini-Huygens. In 2013 after encounter some technical issues and funding in the early 2010s, development was paused although overall research continued. One issue is the other big NASA missions such as in astrophysics and another is availability of RTG's One proposal was a joint mission between NASA and ESA to send a probe to study the icy satellites of the outer Solar System. There