Some scientists believe alien life was transported to Earth on a comet - a theory known as panspermia.
But if alien life can travel between planets, the opposite may also be true, and parts of Earth could be 'seeding' life elsewhere in the solar system.
The theory has gained traction over the past few years, with scientists claiming that the asteroid that wiped out the dinosaurs took Earth-life to Mars and the moons of Jupiter.
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