16 July 1945
First Quarter, 42% lit
The Trinity test
The first nuclear device was detonated before dawn in the New Mexico desert, with a half moon in the sky.
Fermi dropped scraps of paper as the blast wave passed and estimated the yield from how far they blew. His off-the-cuff figure was within a factor of two of the instrumented answer.
- Date
- 16 July 1945
- Moon computed for
- 05:00 local time, UTC−6
- Phase
- First Quarter
- Illuminated
- 42%
Source: Los Alamos National Laboratory historical record