Free Astronomy Magazine May-June 2020

15 MAY-JUNE 2020 certain organisms prevent or mitigate the harmful effects caused by the most ener- getic radiation that reaches the Earth’s sur- face. To do this, these organisms use par- ticular proteins and pigments as anti-UV screens. The task of these biological screens is to absorb UV light and to almost instantly re-emit radiation at longer wavelengths, dissipating any residual energy in the form of heat. In an aquatic environment with shallow waters, biofluorescence might also play a crucial role in keeping the planets of the red dwarfs inhabited, even if their at- mospheres have been depleted by stellar activity. Very extensive colonies of biofluo- rescent organisms could defend against UV fluxes produced by stellar flares through the production of visible radiation, thus causing a temporary increase in the bright- ness of the planetary surface. R ight, Lisa Kaltenegger and Jack T. O'Mal- ley-James, the two researchers from the Carl Sagan In- stitute who, for some years, have been considering the possibility of discovering fluo- rescent extrater- restrial life.