Planet 9: Hypothetical or Real?
Heard about Planet 9?
Some astronomers predict a planet to orbit the sun with a period of 10,000 years, a mass 5x that of Earth on a highly elliptical and inclined orbit. They want to call it Planet 9.
What evidence supports the existence of such a strange object at the edge of our solar system?
As of September 2019, no observation of Planet Nine had been announced. However, existence of a Neptune-diameter object in the outer Solar System, is not ruled out.
Here's a latest trending video that dives into the mystery of Plane 9.
The planet 9 hypothesis helps explain clustering of orbits of distant Kuiper belt objects.