Panspermia theory
Panspermia is the hypothesis that life exists throughout the Universe, distributed by meteoroids,
asteroids and planetoids.
Panspermia is the theory that life on the earth originated from microorganisms or chemical precursors of life present in outer space and able to initiate life on reaching a suitable environment.
One hypothesis, panspermia states that at least some organic compounds reached early Earth from space. The notion of panspermia rests on the idea that life can travel through interstellar space (the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays ), driven by radiation pressure from the stars in the form of spores that occasionally come to rest on a planet where replication and evolution can occur. This sounds like great science fiction, but it is not as far fetched an idea as one might think.
For example, organic compounds have been isolated from modern meteorites. However, this still doesn't explain how life itself can arise from non–living materials. A more accepted scenario involves a type of chemical evolution in which non–living substances became organized into organic molecules that were eventually capable of self–replication.