Lichens and algae could be the first life forms we find on Earth-like exoplanets, by looking for their light signatures in a planet's distinctive colouring.
Astronomers have found several rocky worlds in the habitable zone, the region around a star where liquid water can exist on a planet's surface, and many more are thought to exist. As telescopes get more sensitive, we should be able to collect light reflected off such planets and look for clues to their surface conditions.
Seen from space, Earth gives off a large amount of near-infrared light, which is reflecting off the chlorophyll in plants. We might see a similar "red edge" on distant exoplanets if they also host green vegetation.
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