A team of international researchers ran simulations of the early stages of our solar system and found that a planet lying beyond our solar system may orbit our sun. But if it exists, it is much further away than early 20th-century astronomers hypothesized.
The study, which is still awaiting peer review, says any such hidden planets likely exist in the Oort Cloud, a large collection of icy objects that float on all sides of our solar system unlike planets and the Kuiper Belt, which primarily sit on the same flat disk around the sun.
For an idea of how far out the Oort Cloud is, the closest star, Proxima Centauri, sits about 268,770 AU (25.3 trillion miles) away from the sun. It is because of this vast distance, and the chaotic nature of the Oort Cloud that makes figuring out what is out there so difficult.
The study states the chances of a massive planet roaming the Oort Cloud are very slim but non-negligible. They estimate there is a 0.5% chance such a planetary body formed during the solar system’s formation, and a 7% chance that the sun’s gravitational pull stole such an object from another system.
The researchers say it is far more likely the Oort Cloud is made up of icy rocks, with the largest objects about the size of a mountain.
While it may not be the planet Lowell was looking for, and it definitely would not affect Neptune or Uranus’ orbits, Planet X may indeed be out there somewhere.