The nuclear cannon dubbed "Atomic Annie" fires a 280 millimeter nuclear artillery shell packing 15 kilotons of explosive force, in this breathtaking image from 1953's Operation Upshot-Knothole in Nevada. Check out more images from our only nuclear artillery test.

Flickr user Nevada Tumbleweed has been posting dozens of pics from the 1953 nuclear cannon test, and they're as notable for the beautifully clunky 1950s hardware as for the actual devastation of the nuclear shell, detonated just 500 feet above the ground. And I feel really bad for the soldiers crouching in the trench nearby — I don't think that trench turned out to be all that helpful. More at the link. [Nevada Test Site - Operation Upshot-Knothole - 1953 on Flickr]