Most comets that reach the inner solar system comes from the Oort Cloud on the outer edge of the outer solar system, and some astronomers think that a massive planet, possibly larger than Jupiter is lurking out there unseen in the darkness of deep space.
At the American Astronomical Society meeting in Boston, a research team from NASA’s Ames Research Center presented new data suggesting that the easiest way to explain why comets enter our solar system in elliptical patterns would be if there was a large planet-sized object orbiting out there at about a quarter of a light-year distance. This object would be at a minimum the size of Jupiter, but it could be up to a few times Jupiter’s mass, putting it into brown dwarf territory.
Brown dwarfs are gas giants that are not quite large enough to light up like stars, but still big enough for their gravity to sometimes cause internal fusion. Generally this happens at about ten times the mass of Jupiter, which might be a big large for this hypothetical hidden planet, but there’s still a lot of unknowns about what its characteristics might be, and it may not even exist at all.
The idea that there’s a brown dwarf star orbiting our sun at the outer reaches isn’t a new theory, but it’s one that some astronomers keep coming back to in order to try and explain oddities in and outside the Oort Cloud. But despite decades of searching, no one’s found anything out there any bigger than some dwarf planets.