Planet nine from outer space has yet to be found, but the theory is sound, and the hunt has begun. Since the announcement by Konstantin Batygin and Mike Brown on January 20th, astronomers have been finding ways to search for the theorized planet, using all the available data to zero in on it’s position. It’s certainly big enough to find, at roughly 10 Earth masses, but with a huge swath of space to search, everything that excludes part of the search area is a step in the right direction.
One of the ongoing goals of researchers is to carefully calculate the orbits of the planets in the solar system and the distance to them from Earth. Using data from telescopes like the Cassini spacecraft, they can pinpoint the distance to different worlds. In particular, Cassini data has constrained the Earth-Saturn distance to an uncertainty of 100 m.
The interesting thing the researchers noticed is that depending on the position of theorized planet nine, it would induce tiny orbital perturbations in Saturn. So by using Cassini data, they could figure out if their models matched the observed position of Saturn.
By comparing the Cassini data over the last 12 years to models of perturbations in Saturn’s position, due to planet nine, they were able to rule out huge angular distances in the search, saving time and effort down the road in attempting to locate the planet.
We won’t know for sure if planet nine exists until it is observed, but narrowing down the search area gives astronomers a much better chance of coming to a conclusion, whether we find it or not.