Another ingredient to add to the stew is this: http://www.cfa.harvard.edu/news/2012/pr201212.html There are supposedly a number of "rogue planets" greater than the number of stars, which were ejected from their systems. These scientists claim based on "simulations" that the rogues can be captured by other stellar systems, and 3-6% of stars would thus-capture a rogue. "Stars trade planets just like baseball teams trade players," said Hagai Perets of the Harvard-Smithsonian Center for Astrophysics. This (a) gives another mechanism for panspermia and (b) suggests that there could be some serious risks for Earth... assuming their claims are not crazy... I think, however, there is considerable likelihood their claims are crazy. Why? If they were correct then since the number of stars and rogues were assumed in their sim to be exactly equal, we would conclude that stellar "near miss" swingbys at distances well within the solar system, would occur for well over 3-6% of all stars. I.e. about 100%. That in turn would mean that solar systems basically could not exist. But we know many exist and they are suspected to be quite common.. How can this contradiction be resolved? The press release says their sim focused not on Joe Average Star, but rather stars in "young clusters." Oh. It did not give a link to actual paper, so one's left kind of guessing. -- Warren D. Smith http://RangeVoting.org