Two recent studies have shown that the existence of a mysterious, hypothetical Planet Nine could explain why the planets in our Solar System don’t fully line up with the Sun. Researchers have been speculating about a ninth planet since January this year, and these latest studies add more weight to the hypothesis that, at some point in time at least, there was an extra planet orbiting our Sun.
In fact, if Planet Nine does exist (or did), it would help to explain something that scientists have puzzled over for decades – why the Solar System is tilted.
What does that mean?
Well, basically, all of the prime 8 planets that orbit our Sun do so on the same plane, making the Solar System look like a disc. The problem is that the Sun spins at a different angle, with its axis roughly 6 degrees off from the rest of the planets.
In the past, researchers have attempted to explain this slant by blaming the temporal tug of passing star or interactions between the Sun’s magnetic field and the disc of the dust that formed an our planets. But none of these hypotheses have fully accounted for the misalignment.
“Using an analytic model for secular interactions between Planet Nine and the remaining giant planets, here we show that a planet with similar parameters can naturally generate the observed obliquity as well as the specific pole position of the sun’s spin axis, from a nearly aligned initial state,” the team states.
“Thus, Planet Nine offers a testable explanation for the otherwise mysterious spin-orbit misalignment of the solar system.”
In the French study, conducted by astronomers at the Côte d’Azur Observatory in Nice, the team suggests that Planet Nine’s tilt is likely to blame for this misalignment, rather than its mass.
According to the researchers, while mass is often used to explain why objects in space influence one another – and that’s what the Caltech team looked into – in this case, it would mean that Jupiter – the juggernaut of our Solar System – could have caused the tilt, which it didn’t.
Instead, their models showed that Planet Nine’s tilt could have skewed everything else – coming to the same conclusion as the Caltech researchers. Combined, the results of both the studies add a significant amount of evidence that Planet Nine exists, though not enough to actually prove it.
Instead, the studies seem to say that something influenced the early Solar System and made the mysterious 6-degree tilt – and Planet Nine fits the profile.
While Planet Nine will stay hypothetical until researchers manage to actually find it in the night sky, it’s not stopping researchers from piling up evidence of its existence. For example, revert in April, a team started devising a way to spot the planet using black-body radiation, which basically scans the sky for hotspots that could be planets cooling down.
These latest results haven’t been peer-reviewed as yet, so we need to take them with a grain of salt for now. While the debate over Planet Nine will likely continue well into the future, it’s exciting to see that it fits into models explaining why our Solar System is the way it is.