It was long a well known truth that our solar system had nine planets, until scientists realized that Pluto was, in fact, a dwarf planet. Dwarf planets are planetoids which meet two of the criteria for a planet — being an object large enough to crush itself into a sphere, but not large enough to cause thermonuclear fission — but has failed to clear its domain of space debris. For a few years after our conception of the solar system was shocked, all was well and stable, but then astronomers started noticing a strange attribute of five objects in the far reaches of our universe: they all had strangely eccentric — meaning elliptical instead of circular — orbits which aligned into a plane, and they all orbited in the same direction.
Mike Brown, an astronomer at the California Institute of Technology and the leader of the team who discovered these objects, came to the conclusion that there was less than a one percent chance that all five orbits would align without some outside force influencing them. To solve the mystery, he enlisted the help of Theoretical Astrophysicist Konstantin Batygin.
The answer they came up with was that there must be some massive object in the solar system that affects their orbits. The thing is, when they started to look at possible orbital paths that would allow them to interact and cause that pattern, they realized that this hypothetical Planet Nine would only be close enough to these five objects every 50,000 years or so. If this is the case, then Planet Nine would have to be truly huge — at least ten times the size of Earth.
While the scientific community has generally been skeptical about claims to have found a new planet in the solar system, for obvious reasons, it seems like this time is different. This time, the math actually checks out, and it points astronomers to the supposed location of this new planet. As of now, the two scientists are using a telescope named Subaru to scan swathes of the sky, but it could still take over five years for them to scan all of the potential ninth planet’s expected location. Keep an eye on your favorite source of science news, and wait to see if this pans out!