The dark obelisk on the left side of the photo indicates the exact location where at 5:29:45 a.m. on July 16, 1945 Mountain War Time (MWT) the first nuclear device, referred to as 'Gadget'. was exploded. The device used a Plutonium-239 ball surrounded by conventional explosives. The force of the conventional explosives when set off would be directed inward to set off a chain reaction. This device was the more complicated of the two devices designed for a nuclear bomb, and was also used in 'Fat Man' which was dropped on Nagasaki on August 9, 1945. 'Gadget' was mounted on a 100-ft tall steel tower. The site is located in the remote Jornado del Muerto within the White Sands Missile Range . Three observation points were established at 10,000 yards from ground zero. These wooden shelters were protected by concrete and earth and one of these was used to trigger the automatic firing device. Many scientists and support personnel, including Maj. Gen. Leslie Groves, head of the Manhattan Project, watched the explosion from base camp which was ten miles southwest of ground zero. Most visiting VIPs, like Edward Teller, watched from Compania Hill, 20 miles northwest of ground zero. The explosion made a shallow, 4-ft deep depression 200-ft in diameter and the blast vaporized the 100-ft high steel tower and melted the desert sand and turned it into a green glassy radioactive substance, called Trinitite. The shock wave from the explosion broke windows 120 miles away and was felt by many at least 160 miles away. The army explained this as an explosion of a large munitions storage area. Today, the site is open to the public twice a year, the first Saturdays of April and October. This picture was taken on 7 October 2017, Sig...