In the Appalachian firefly Photinus carolinus, flying males flash in synchrony with their neighbors, creating a symphony in light. Photo by Radim Schreiber.

Sara Lewis studies fireflies. And it turns out they’re not just a pretty flashing light on a summer night. She explains how a firefly glows — and how humans are harnessing that glow for health and medical research (and even to make our food safer).

Ocean explorer Edith Widder shares the astoundingly sophisticated language of bioluminescent creatures, which can light up the depths of the seas like a “snow storm.”