Mysterious Planet Nine May Have Tilted the Entire Solar System

A team of scientists from the California Institute of Technology in Pasadena claims that they have found evidence suggesting that the so-called "Planet Nine" might have tilted the entire solar system except the sun.

Their findings, presented at a joint meeting of the American Astronomical Society's Division for Planetary Sciences and European Planetary Science Congress in Pasadena, California, showed that existence of a 10 Earth mass planet could help explain why the orbit of the eight major planets are tilted by about six degrees compared to the sun's equator.

"The Sun is staying put in its fixed reference frame and it's the planetary orbits that are being tilted by Planet Nine. So Planet Nine has tilted the entire disk of the solar system by 6 degrees and because we live on that disc ... to us it looks like the Sun is tilted, but it's actually the other way around," explained Konstantin Batygin, a theoretical astrophysicist at Caltech and co-author of the study, in an interview with Astronomy.

Using computer simulations, the researchers showed that the tilt of the eight major planets were influenced by the gravitational pull of an undiscovered ninth planet over the 4.5 billion years lifetime of the solar system.

The researchers are attributing the ability of the Planet Nine to influence the entire solar system to its long orbit. Due to its huge orbits, Planet Nine can assert quite a bit of torque on the inner planets without applying much force. Furthermore, the large orbit of Planet Nine gives it as much angular momentum as the entire solar system combines, explained Batygin.

There are other possibilities that can explain the tilt of the solar system. However, the researchers noted that these other explanations are really hard to test and invoke processes that were possibly present early in the solar system.

"Planet Nine is the first thing that has been proposed to tilt the solar system that doesn't depend on early conditions, so if we find Planet Nine, we will be able to see if it's the only thing responsible for the tilt, or if anything else may have played a role," said Elizabeth Bailey, an astrophysicist and planetary scientist at Caltech and lead author of the study, in a report from Space.