Science

by Katy Steinmetz / San Francisco

by Ainissa Ramirez and Salima Koroma

by TIME Photo

by Justin Worland

by Julia Zorthian

by Nolan Feeney

by Joanna Plucinska

by Maya Rhodan

by Justin Worland

by Tessa Berenson Rogers

by John Anderson

by Justin Worland

by Jeffrey Kluger

by Jeffrey Kluger and Heather Jones

by TIME Photo