Just before dawn on July 16, 1945, U.S. scientists conducted a test that would change the world forever. They stood in awe as a bright flash of light exploded into a ball of fire, illuminating the New Mexico desert and destroying all life within a mile of the blast. This successful test of the first atomic bomb ushered the world into the nuclear age. The United States used this new bomb to destroy the Japanese cities of Hiroshima and Nagasaki to end World War II. Today other countries have developed their own atomic bombs, and the bombs' fearsome power continues to shape our world.