In the above photo the large, dark crater was created by the Trinity device. Beneath it you will see a light ring with a small, dark "dot" at it's center. The small dot is the crater formed a few months earlier by a detonation of 100 tons (.1 kiloton) of high explosives used to calibrate the power of the Trinity shot.
Sixty-six years ago today, scientists at the Trinty test site in Alamagordo, NM, detonated the first nuclear weapon.
Its yield was estimated at 21 kilotons. It left a crater a half mile wide. The fused green glass created by 10,000,000 F temperatures is still radioactive today.
A year later on July 25, 1946, the second nuclear test ("Shot Baker") at the Bikini Atoll destroyed or damaged a 70 ship target flotilla. This second test was an underwater detonation that proved far more powerful than the previous Bikini Atoll aerial test ("Shot Alpha") earlier in the year. In this second Bikini test, ships of the target flotilla included the famed aircraft carrier USS Saratgoa (sunk - her bottom ripped out by the explosion) and the battleship USS Nevada (heavily damaged).