Planet 9, a hypothetical, as-yet undetected planet, is believed to have been captured by our solar system at some point over its 4.6 billion year history.
Now, Harvard University astronomers have raised the possibility that orbital evidence for Planet 9 could actually be the result of a hypothetical primordial black hole (PBH).
Planet 9 or primordial black hole?
In a paper published in The Astrophysical Journal Letters, the researchers argue that clusters of objects on the fringes of our solar system suggest there could be a massive super-earth type body lying beyond Pluto.
The authors propose that a wide-field survey telescope, which is now being constructed in Chile, the Large Synoptic Survey Telescope (LSST), may allow us to verify their hypothesis, and see whether Planet 9 is a PBH instead of an ordinary planet.
"Planet Nine could be a grapefruit-sized black hole with a mass of five to ten times that of the Earth," Amir Siraj, a Harvard undergraduate student involved in the study, said in a press release.
Understanding dark matter
If PBH's do exist they might help us to solve the mystery of the universe's dark matter and would require new physics to be formulated in order to account for their existence, Forbes explains.
According to the scientists behind the paper, if Planet 9 is a black hole, then comets passing through the 'Oort Cloud' on the fringes of our solar system would visibly flare when impacting the space object.
For comets of a large enough size, this flare of light would be detectable by the LSST’s 8.4-meter optical telescope.
If 'Planet 9' is a black hole, Avi Loeb, Chair of Harvard University’s Dept told Forbes, that means there should be fifty quadrillions like it in the Milky Way alone.