Searching for Planet 9 and where new research fits into the overall existence of a theoretical super-Earth beyond Neptune
February 24, 2021
In large part, it is impossible to have escaped notice of a rather large debate swirling in the planetary community around a theorized super-Earth planet in the outer reaches of our solar system, the existence of which could be one possible explanation to several oddities observed in a very dynamic part of our galactic home.
So where does current research, distant solar system observations, and searches for the theoretical super-Earth, known both as Planet 9 or Planet X, reside?
To start, a brief history. The first proposals regarding the current Planet 9 candidate stemmed from a prolonged series of observations of extreme trans-Neptunian objects, or eTNOs. These are small rocky objects whose orbits are well beyond that of Neptune’s and have a semi-major axis (average orbital distance) of 150-250 AU (Astronomical Units, with 1 AU equaling approximately 149,000,000 km or the average distance from the Earth to the Sun).