Planet nine

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.[1][4][5]

In a 2014 letter to the journal Nature, astronomers Chad Trujillo and Scott S. Sheppard inferred the possible existence of a massive trans-Neptunian planet from similarities in the orbits of the distant trans-Neptunian objects Sedna and 2012 VP113.[4]On 20 January 2016, researchers Konstantin Batygin and Michael E. Brown at Caltech explained how a massive outer planet would be the likeliest explanation for the similarities in orbits of six distant objects, and they proposed specific orbital parameters.[1] The predicted planet could be a super-Earth, with an estimated mass of 10 Earths (approximately 5,000 times the mass of Pluto), a diameter two to four times that of Earth, and a highly elliptical orbit with an orbital period of approximately 15,000 years.[6]

On the basis of models of planet formation that might include planetary migration from the inner Solar System, such as the five-planet Nice model, Batygin and Brown suggest that it may be a primordial giant planet core that was ejected from its original orbit during the nebular epoch of the Solar System's evolution.[1] Others have proposed that it was captured from another star,[7] or that it formed on a very distant circular orbit and was perturbed onto its current eccentric orbit during a distant encounter with another star.[8][9]

Planet Nine does not have an official name, and it will not receive one unless its existence is confirmed, typically through optical imaging. Once confirmed, the IAU will certify a name, with priority typically given to a name proposed by its discoverers.[10] It will likely be a name chosen from Roman or Greek mythology.[11] work cited:https://en.wikipedia.org/wiki/Planet_Nine