Panspermia is a Greek word that translates literally as "seeds everywhere". The panspermia hypothesis states that the "seeds" of life exist all over the Universe and can be propagated through space from one location to another. Some believe that life on Earth may have originated through these "seeds".
Mechanisms for panspermia include the deflection of interstellar dust by solar radiation pressure and extremophile microorganisms traveling through space within an asteroid, meteorite or comet.
Three popular variations of the panspermia hypothesis are:
- Lithopanspermia (interstellar panspermia) - impact-expelled rocks from a planet's surface serve as transfer vehicles for spreading biological material from one solar system to another.
- Ballistic panspermia (interplanetary panspermia) - impact-expelled rocks from a planet's surface serve as transfer vehicles for spreading biological material from one planet to another within the same solar system
- Directed panspermia - the intentional spreading of the seeds of life to other planets by an advanced extraterrestrial civilization, or the intentional spreading of the seeds of life from Earth to other planets by humans
Panspermia does not provide an explanation for evolution or attempt pinpoint the origin of life in the Universe, but it does attempt to solve the mysteries of the origin of life on Earth and the transfer of life throughout the Universe.