Since the time of Trinity -- the first nuclear explosion in 1945 -- nearly 2,000 nuclear tests have been performed, with the majority taking place during the 1960s and 1970s. When the technology was new, tests were frequent and often spectacular, and led to the development of newer, more deadly weapons. But starting in the 1990s, there have been efforts to limit the future testing of nuclear weapons, including a U.S. moratorium and a U.N. comprehensive test ban treaty. As a result, testing has slowed -- though not halted -- and there are questions about the future. Who will take over for those experienced engineers who are now near retirement, and should we act as stewards with our enormous stockpiles of nuclear weapons? Gathered here are images from the first 30 years of nuclear testing. See also "Can We Unlearn the Bomb?" and "Atomic Weapons on Film."

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© US DODA fireball begins to rise, and the world's first atomic mushroom cloud begins to form, nine seconds after Trinity detonated on July 16, 1945.

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© US DODThe expanding fireball and shockwave of the Trinity explosion, seen .025 seconds after detonation on July 16, 1945.
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© US DODA longer-exposure photograph of the Trinity explosion seconds after detonation on July 16, 1945.
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© US DODJumbo, a 200-ton steel canister designed to recover the plutonium used in the Trinity test in the event that the explosives used were unable to trigger a chain reaction. In the end, Jumbo wasn't used for recovery, but was placed near ground zero to help gauge the effects of the blast. It survived intact, but its support tower did not.
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© US DODLos Alamos director J. Robert Oppenheimer is seen in silhouette as he oversees final assembly of The Gadget at the Trinity test site in July of 1945.
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© US DODExposed wiring of The Gadget, the nuclear device which exploded as part of Trinity, the first nuclear weapons test of an atomic bomb. At the time of this photo, the device was being prepared for its detonation, which took place on July 16, 1945.
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© US DODU.S. military observers watch the explosion during Operation Crossroads Baker, a nuclear test conducted on Bikini Atoll on July 25, 1946. This was the fifth nuclear explosion ever, after two other tests and the two bombs dropped on Hiroshima and Nagasaki.
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© APA massive column of water rises from the sea as the U.S. detonate an atom bomb at Bikini Atoll in the Pacific in the first underwater test of the device, July 25, 1946.
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© APA huge mushroom cloud rises above Bikini atoll in the Marshall Islands on July 25, 1946 following an atomic test blast, part of the U.S. military's Operation Crossroads. The dark spots in foreground are ships that were placed near the blast site to test what an atom bomb would do to a fleet of warships.
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© US DODOperation Greenhouse took place in the spring of 1951, consisting of four explosions at the Pacific Proving Grounds in the Pacific Ocean. This photo is from the third test, George, on May 9, 1951, the first thermonuclear bomb test, yielding 225 kilotons.
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© US DOD"Rope tricks" are seen in this image of a nuclear explosion taken less than one millisecond after detonation. During operation Tumbler-Snapper in 1952, this nuclear test device was suspended 300 feet above the Nevada desert floor, and anchored by mooring cables. As the ball of plasma expanded, the radiating energy superheated and vaporized the cables just ahead of the fireball, resulting in the "spike" effects.
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© US DODThis "Survival Town" house, photographed recently, was built some 7,500 feet from a 29-kiloton nuclear detonation -- it remained essentially intact. Survival Town consisted of houses, office buildings, fallout shelters, power systems, communications equipment, radio broadcasting station, and trailer homes. The test, called Apple II, was fired on May 5, 1955.
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© US DODUpshot-Knothole Grable, a test carried out by the U.S. military in Nevada on May 25, 1953. A 280mm nuclear shell was fired 10km into the desert by the M65 Atomic Cannon, detonating in the air, about 500 feet above the ground, with a resulting 15 kiloton explosion.
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© AP PhotoThe test explosion of a hydrogen bomb during Operation Redwing over the Bikini Atoll on May 20, 1956.
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© National Nuclear Security Administration / Nevada Site OfficeIonization glow surrounds the cooling fireball of the Diablo shot, fired in Yucca Flat at 4:30 a.m. Monday, July 15, 1957.
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© National Nuclear Security Administration / Nevada Site OfficeThe fireball of the Priscilla shot, fired on June 24, 1957, as a part of the Operation Plumbbob series.
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© National Nuclear Security Administration / Nevada Site OfficeNATO observers watch the detonation of Operation Plumbbob Boltzmann on May 28, 1957.
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© National Nuclear Security Administration / Nevada Site OfficeThe tail section of a U.S. Navy Blimp is shown with the Stokes cloud in background at the Nevada test Site on August 7, 1957. The blimp was in temporary free flight in excess of five miles from ground zero when it was collapsed by the shock wave from the blast. The airship was unmanned and was used in a military effects experiment.
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© National Nuclear Security Administration / Nevada Site OfficeObservers view atmospheric testing during operation Hardtack I -- a thermonuclear detonation during the Pacific tests in 1958.
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© US DODExpanding rings surround a mushroom cloud, during the Yeso test explosion, part of Operation Dominic, a series of over 100 nuclear test explosions in Nevada and the Pacific in 1962.
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© US DODShot during Fishbowl Bluegill, this is an image of an explosion of a 400 kiloton nuclear bomb taking place in the atmosphere, 30 miles above the Pacific, as viewed from above, in October 1962.
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© National Nuclear Security Administration / Nevada Site OfficeSedan Crater was formed when a 100 kiloton explosive buried under 635 feet of desert alluvium was fired at the NTS on July 6, 1962, displacing 12 million tons of earth. The crater is 320 feet deep and 1,280 feet in diameter.
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© US DODA view of the Arkansas test, part of Operation Dominic, a series of over 100 nuclear test explosions in Nevada and the Pacific in 1962.
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© US DODThe rising fireball of the Aztec test, part of Operation Dominic, a series of over 100 nuclear test explosions in Nevada and the Pacific in 1962.
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© APA 1971 photo of a nuclear bomb detonated by the French government at the Mururoa atoll, French Polynesia.
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© Pierre J. / CC BY NC SAA photo of a nuclear bomb detonated by the French government at the Mururoa atoll, French Polynesia.