Rogue 9: New simulation suggests distant origin of ‘Planet 9’

13 Jan 2017

Concept image of Planet Nine. Image: Vadim Sadovski/Shutterstock

While debate over Planet Nine’s very existence continues, a new simulation has suggested that if it does, it could be a rogue planet from a distant star system.

It has been almost a year since a team of researchers from the California Institute of Technology (Caltech) put forward considerable evidence for the existence of a giant planet – dubbed Planet Nine – at the edge of our solar system.

Unlike Pluto, which was stricken from the list of planets over a decade ago, this possible planet would have a mass 10 times that of Earth, on an orbit 20 times farther from the sun than Neptune.

This meant its origins were something of a mystery for astronomers as something of this size wouldn’t be able to form this far from a solar source.

But now, a pair of astronomers have presented results on a simulation to this year’s American Astronomical Society meeting that suggests if it does exist, it could have formed in a distant star system, but wound up in our own.

James Vesper and Paul Mason of New Mexico State University ran a number of simulations to find out what would happen if a rogue planet drifted into our solar system.

40pc chance it happened

As it turns out, 60pc of the time, such a planet would drift into our solar system and keep on travelling through space, sometimes taking a smaller planet with it.

But 40pc of the time, the rogue planet was captured in the solar system’s orbit, resulting in what previous astronomers’ calculations appeared to prove.

The simulations also suggested that if such a rogue was captured, it could orbit the sun at the speculated distance.

Yet they added that it was unlikely that a planet any bigger than Neptune has ever entered our solar system, having not been disturbed since the period that the solar system was created.

Speaking last year, Caltech’s Mike Brown – who stripped Pluto of its planetary status – said he was still holding out hope of discovering the planet.

“I would love to find it,” he said. “But I’d also be perfectly happy if someone else found it. We hope that other people are going to get inspired and start searching.”

Colm Gorey was a senior journalist with Silicon Republic