“Judging by the diameter of the crater, it was probably a 1,000 pound bomb, or a 500 kilo bomb, dropped by a medium bomber either from Java or Ambon [in Indonesia],” he said.
“Most likely on February 19  as well.”
Mr Jung says the bomb crater will become a special part of Darwin’s history.
“Often it’s the small things in history that are really important and given that this is the only one, it makes it unique. It’s a unique hole in Darwin,” he said.
Darwin was subjected to 63 bombing raids during the war, with more bombs dropped on the city than Pearl Harbour.