Fireflies produce a 'cold light' without infrared or ultraviolet frequencies using special organs in their abdomen where the enzyme luciferase binds to luciferin in the presence of oxygen, magnesium ions, and ATP.
in honor of firefly's drip marketing finally dropping, i would like for all of us to revisit her conversation with acheron (as sam)... such a poignant character moment that gets lost in the meat of the 2.1 tb mission!