Batygin and Brown’s models suggest that Planet Nine may have a mass about 10 times that of Earth and be similar in size to Uranus or Neptune. The predicted orbit is about 20 times farther from our Sun on average than Neptune, taking between 10,000 and 20,000 years to orbit the Sun. Neptune, by comparison, completes an orbit roughly every 165 years.
Has Planet Nine been found yet?
Although the theorized ninth planet has not yet been directly observed, the search continues.
Batygin and Brown’s team, along with other researchers, have used computer simulations to refine their search. By simulating objects in the outer Solar System, plugging in varying parameters for a potential Planet Nine, and then letting simulated gravity run its course over billions of years, the team can see whether that particular Planet Nine would affect those objects in a way that matches how ETNOs’ orbits have been perturbed. These simulations have ruled out about 78 percent of the sections of space Planet Nine might have been lurking.
Planet Nine hunters are now combing through observational data from advanced telescopes to look for signs of a large planet in the remaining search area, including NASA’s Transiting Exoplanet Survey Satellite. Brown and Batygin also plan to use data from the upcoming Legacy Survey of Space and Time sky survey from the Vera C. Rubin Observatory in Chile.
Who gets to name a new planet?
If a ninth planet is someday discovered, the person who discovers it will get to choose its name, as long as that name is approved by the International Astronomical Union. Planets have traditionally been named after mythological Roman gods.
The possibilities for naming features on its surface, like mountains, craters, and even individual rocks, could be much more creative. For example, mountains on Saturn’s moon Titan are named after mountains from Middle-earth, the fictional setting of J.R.R. Tolkien’s Lord of the Rings novels, and craters on Mercury are named after influential artists, authors, and musicians.
Alternative explanations
The existence of an undiscovered planet isn’t the only possible explanation for the movements of ETNOs. Gravitational effects could be caused by clusters of objects rather than one big one, or by a very distant small black hole. We might also just not know enough about ETNOs to really know what’s happening with them. This was the case with Uranus and Neptune back in the early days of Planet X speculation.
Whatever the case may be, we’ll only find out whether Planet X/Planet Nine exists by studying space.