Significant Nuclear Events:

• First controlled nuclear reaction, CP-1, December 2, 1942, at 3:25 p.m.
   
• First atomic explosion, Trinity, July 16, 1945, at 5:29:45 a.m.
   
• Hiroshima, August 6, 1945, at 8:15 a.m.
   
• The Gadget and Fat Man each had an explosive yield of 21 kilotons of TNT.
   
  • About 1 kg of the approximately 6.15 kg of plutonium in each of these bombs fissioned into lighter elements, totaling almost exactly one gram less, after cooling.
     
  • The heat, light and radiation carried the missing gram of mass.
   
• First thermonuclear explosion, Mike, November 1, 1952, at 7:15 a.m.
   
• Three Mile Island, March 28, 1979, at 4:00 a.m.
   
• Chernobyl, April 26, 1986, at 1:23:40 a.m.