The theory of panspermia holds that life is spread through the cosmos via asteroids, comets, and other objects. When the building blocks of life emerge on one planet, impacts can eject surface material into space, which then carries these seeds to other worlds. For decades, scientists have debated w hether this could have occurred between Earth and Mars (in both directions). However, the recent controversy over the possible existence of microbial life in Venus's dense clouds has sparked discussions of interplanetary transfers between Venus, Earth, and Mars. ...read more read less