Number Of Starless Planets Greater Than Previously Thought

Wandering planets may be much more common than we previously. A study recently published puts the estimated number of these nomad planets in the Milky Way alone in the quadrillions, shedding new light on the way we scour the skies for signs of life-supporting planets.

The study, titled "Nomads of the Galaxy," suggests that there might be up to 100,000 nomad planets per star. Our Milky Way galaxy contains somewhere between 200 to 400 billion stars. If you do the math, the possible number of nomad planets ends up in the quadrillions.

"In the 20th century, many eminent scientists have entertained the speculation that life propagated either in a directed, random or malicious way throughout the galaxy," said Roger D. Blandford, co-author of the study and director of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and the SLAC National Accelerator Laboratory.

"One thing that I think modern astronomy might add to that is clear evidence that many galaxies collide and spray material out into intergalactic space. So life can propagate between galaxies too, in principle."

When looking for life, modern astronomy tends to look towards planets that are within a suitable distance from a star. This would indicate factors such as temperature and atmosphere which might give rise to water. If there is liquid water, there might be a chance that biological life as we know it, could have formed. This is why there is such an intense probing of Mars to find liquid H₂0. 

"Water is probably the best solvent in the universe," Jeffrey Bada, a planetary scientist at the Scripps Institution of Oceanography in La Jolla, California told NOVA. "Everything is soluble in water to some degree." 

Other techniques involve scanning the airwaves for any radio signals that might have emanated from intelligent life.

In any case, there is now evidence that there are an incredible amount of planetary bodies not circling stars - and while the odds of finding life on them are still infinitesimal, they are certainly higher than before.