 Sweeney then proceeded to the alternative target , Nagasaki . It too was obscured by cloud , and Ashworth ordered Sweeney to make a radar approach . At the last minute , the bombardier , Captain Kermit K. Beahan , found a hole in the clouds . The Fat Man was dropped and , following a 43 @-@ second duration free fall , it exploded at 11 : 02 local time , at an altitude of about 1 @,@ 650 feet ( 500 m ) . Because of poor visibility due to cloud cover , the bomb missed its intended detonation point by almost two miles , and damage was somewhat less extensive than that in Hiroshima . 
