Free Astronomy Magazine May-June 2020

MAY-JUNE 2020 of the two Cornell researchers becomes even more relevant. We already know that lifeforms would be able to survive and per- haps proliferate in a hostile environment, such as that on Mars (where UV rays con- tinuously hit the surface), simply by shelter- ing under rocks or within the ravines along the surface. That said, such lifeforms are not remotely detectable. What Kaltenegger and O’Malley-James pro- pose is something different − something vis- ible from Earth. Let’s suppose that, in the habitable zones of some nearby red dwarfs, there are plan- ets that have managed to maintain a suffi- ciently thick atmosphere (observations go in this direction) to prevent possible surface oceans from evaporating completely. In this case, there could be aquatic lifeforms that defend themselves from UV rays just by re- maining immersed and reacting through biofluorescence to that part of the incom- ing radiation not shielded by the water. Biofluorescence is a mechanism by which I n this illustra- tion, flares from a red dwarf acti- vate the biofluo- rescence of life- forms that cover the shallow ocean floors of a planet, elevating the planet-star con- trast. [adapted from NASA image]