Planet 9

Planet 9 is a hypothetical object in the far outskirts of the outer solar system. It is said to be around five to ten Earth masses. It is possibly a super-Earth, if so in similar composition to Pluto, if it is a super-Earth, it will be the largest terrestrial planet, surpassing earth in size. It could also be a mini-Neptune, or small ice giant meaning it would be similar to Uranus and Neptune, but smaller, if this is the case it will be the smallest gas planet in our solar system. It could also be a primordial black hole around the size of a grapefruit, formed around the start of the universe, in this is the case, at some point the timeline of our solar system, it was caught by the sun's gravitational force. Whatever Planet 9 is, it has a strong chance to be real due to highly elliptical orbits of distant TNOs, or Trans Neptunian Objects, such as Sedna, which at it's closest approach to the sun is 76 AU or 76 times farther from the sun than earth, but the farthest being 937 AU or 937 times farther from the sun than earth. The James Web Space Telescope and LSST or Large Synoptic Survey Telescope could greatly help discover Planet 9.

Hopefully Planet 9 will be discovered soon.