[U-238]

Rogue Planets are not unusal in astronomy.

http://www.bbc.co.uk/news/science-environment-13416431
http://blogs.discovermagazine.com/badastronomy/2011/05/18/the-galaxy-may-swarm-with-billions-of-wandering-planets/

[jveritas]

Astronomy, the Science with a lot of BS... Not all of it but a huge part of it is just BS...