Atomic power is energy that is released from the splitting of atoms in a process called nuclear fission. In the early 20th century, scientists discovered that by splitting the atoms of certain kinds of matter such as uranium, huge amounts of energy are released. By 1939, American scientists understood the possibility of adapting this technology to create an atomic bomb. Physicist Albert Einstein warned President Roosevelt of the danger of atomic science in German hands. In 1942, as Germany and other nations worked on their own atomic devices, Roosevelt established the Manhattan Project to research and develop atomic weapons. Led by physicist Robert Oppenheimer, U.S. scientists exploded their first atomic bomb in July 1945 at Alamogordo, New Mexico. In August, after President Truman approved the use of atomic weapons against Japan, U.S. planes bombed the cities of Hiroshima and Nagasaki.
