Tiny organisms embedded in rocks expelled from other planets that then smashed into Earth could have brought life to the planet, according to researchers presenting computer simulated evidence of such occurrences at the European Planetary Sciences Congress in September. The researchers report that the solar system and its nearest planetary neighbors could have swapped rocks via asteroids or meteors at least 100 trillion times well before the Sun struck out from its native star cluster. Furthermore, existing rock evidence shows that basic life forms could indeed date from the Sun's birth -- and have been hardy enough to survive an interstellar journey and eventual impact.
