 The show takes its name from the " Firefly @-@ class " spaceship , Serenity , that the central characters call home . It resembles a firefly in general arrangement , and the tail section , analogous to a bioluminescent insectoid abdomen , lights up during acceleration . The ship was named after the Battle of Serenity Valley , where Mal and Zoe were on the losing side . It is revealed in " Bushwhacked " that the Battle of Serenity Valley is widely considered the loss which sealed the fate of the Independents . 
