Our galaxy is filled with rogue planets that don't orbit around a star, according to researchers at the Kavli Institute for Particle Astrophysics and Cosmology. In fact there could be thousands, perhaps billions of "nomad planets" hurtling around the galaxy and far outnumbering the stars.

The team of astronomers raised the possibility of a galaxy teeming with rogue planets in a publication released last Thursday. The study hints that rogue planets are more numerous than astronomers previously thought. Rogue planets could outnumber the 200 to 400 billion stars in the Milky Way by 100,000 to 1.

The astronomers reached that astonishing conclusion after doing a bit of math. Astrophysicist Louis Strigari and his colleagues added the mass of all the comets, planets and stars in the galaxy and found that the mass didn't come close to the galaxy's total mass. The missing mass could only be attributed to unknown objects. According to the group's calculations there are at least 100,000 nomad planets for every main sequence star in our galaxy.

"To paraphrase Dorothy from The Wizard of Oz, if correct, this extrapolation implies that we are not in Kansas anymore, and in fact we never were in Kansas," said Alan Boss of the Carnegie Institution for Science in a Stanford press release. "The universe is riddled with unseen planetary-mass objects that we are just now able to detect."

Rogue planets can get ejected from their original host stars for a various reasons. The nomad planet could have drifted too close to the star or its parent star could have gone supernova and ejected the planet into outer space.

It would take until the next generation of telescopes to confirm the team's assertion of a galaxy filled with wandering solo planets. Work is underway to develop a terrestrial telescope that will help astronomers look for nomad planets but they aren't scheduled to go online until 2020. However the existence of these rogue planets leads to some very intriguing scenarios. Could any of these nomad planets host alien life?

"If any of these nomad planets are big enough to have a thick atmosphere, they could have trapped enough heat for bacterial life to exist," said Strigari.

The team's conclusions are published in the Monthly Notices of Britain's Royal Astronomical Society.