Between 1939 and 1945, World War II brought many innovations and inventions to the world. New countries, organizations, weapons, and technological advances were produced. The three that had the greatest impact on the war were the invention of the radar, the airplane, and the atomic bomb because of their effective use. The first practical radar system was invented in 1935 by Scottish physicist Robert Alexander Watson, but was later developed by the British during World War II. Radar was used to determine where a distant object was, how big it was, what shape it was, how fast it was moving, and in which direction it was going. When Germany sent 2,000 planes every night for two full months to try to gain control of the skies by destroying Britain's nuclear air force, British pilots accurately tracked the flight paths of German planes, even in the dark, thanks to radar. Radar is important because it prevents planes from colliding with each other and today it is used to manage traffic control, to detect missiles and to detect weather conditions. Aircraft had a major impact on World War II, they were the main weapon. World War II fighter planes featured all the innovations of the 1930s. Piston-engined fighters continued to be refined and developed with increasing performance and capability. Planes were used during World War II because they were fast and because they could attack both on land and at sea. Planes have had an impact on world history because they were used to attack Britain by the Germans, they were used in the attack on Pearl Harbor, and they were used to drop the atomic bomb on Hiroshima and Nagasaki. Aircraft played a significant role because they were the main attack tool used in this war. Unlike airplanes, the atomic bomb was not used as much but it created more damage than airplanes and ended the war. The explosive power of the atomic bomb originates from the splitting of the nucleus of a heavy atom. The uranium in an atomic bomb can release a million times more energy than TNT. The fission bomb impacted the world because it wiped out Hiroshima and Nagasaki, killing approximately 140,000 people and injuring thousands. These bombs created thermal radiation, which results from the extremely high temperatures created by an atomic explosion, causes severe burns on exposed parts of the body and can start fires over a wide radius.