Nomad Planets

Here's something that I completely ignored, the existence of nomad planets, which may contain bacterial life. Let me explain, this planets do not orbit a star, but that roam in space, and it seems that these planets are 100,000 times more than the Milky Way stars, this according to a recent study by researchers of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) a joint institute of Stanford University and the SLAC National Accelerator Laboratory.
If it would be confirmed, all of this will affect the current theories of planet formation, as well as all knowledge of the origin of life.  Louis Strigari, leader of the team that reported the result, said “ 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”. This heat is generated by the tectonic activity, and internal radioactive decay, since they don't exploit the heat of any star.

Illustration courtesy Caltech/NASA for NatGeo

If you want to know more about the subject can read the rest of the article here:http://news.stanford.edu/news/2012/february/slac-nomad-planets-022312.html

Or here: http://news.nationalgeographic.com/news/2012/02/120224-rogue-nomad-planets-stars-black-holes-space-science/