The origin of life is one of the greatest mysteries of science. So far, life has only been known from our home planet, Earth. And while on other celestial bodies, some of which are quite life-friendly, there has apparently been a yawning emptiness for billions of years, life on Earth appeared quite soon after its formation: after our planet cooled down more than four billion years ago and liquid water covered its surface for the first time, it no longer took a few hundred million years before the first living creatures appeared.
