But ... we may well get visitors in teeny tiny forms . We may well have done for aeons,  but in small ways , such as has been suggested with comets.

They have watery and/or icy tails, Plus they can travel vast elliptical distances throughout space and time and  for vast and lengthy periods.

 It seems the most likely way to hitchhike through the galaxy to me. To even be  deposited or dispursed through out space and planets generally. I imagine microbes could be carried on the back of debris ,that in turn fall away from the comet as it passes planets with gravity pulling in little aliens!

Last Edited By: samson Apr 27 12 12:18 AM. Edited 1 times.