Eyewitness Report by O.R Frisch
“I watched the explosion from a point said to be about 20 (or 25) miles away and about north of it, together with the members of the coordinating council. Fearing to be dazzled and burned by ultraviolet rays, I stood with my back to the gadget and behind the radio truck. I looked at the hills, visible in the first faint light of dawn (0530 M.W. Time). Suddenly and without any sound, the hills were bathed in brilliant sunshine, as if somebody had turned the sun on with a switch. It is hard to say whether the light was less or more intelligent than full sunlight since my eyes were pretty well dark-adapted. The hills appeared flat and colorless, like a scenery seen by the light of a photographic flash, indicating presumably that the retina was stimulated beyond the point where intensity discrimination is adequate. The light remained constant for about one or two seconds (probably for the same reason) and gradually diminished. After that, I turned around and tried to look at the light source but found it still too bright to keep my eyes on it. A few short glances gave me the impression of a small, very brilliant core much more minor in appearance than the sun, surrounded by decreasing and reddening brightness with no definite boundary, but not more significant than the sun. After some seconds, I could keep my eye on the thing, and it now looked like a pretty perfect red ball, about as big as the sun, and connected to the ground by a short gray stem. The ball rose slowly, lengthening its stem and getting gradually darker and slightly larger. A structure of darker and lighter irregularities became visible, making the ball look like a raspberry. Then its motion slowed down and flattened out but remained connected to the ground by its stem, looking more than ever like an elephant’s trunk. Then a hump grew out of its top surface, and a second mushroom grew out of the top of the first one, slowly penetrating the highest cloud layers. As the red glow died out, it became apparent that the whole structure, particularly the top mushroom, was surrounded by a purplish blue light. A minute or so later, the ultimate mushroom appeared to glow feebly in this color, but this was no longer easy to see in the increasing light of dawn.
A very striking phenomenon was the sudden appearance of a white patch on the underside of the cloud layer just above the explosion; the patch spread very rapidly, like a pool of spilled milk, and a second or two later, a similar patch appeared and lay on another cloud layer higher up. They marked no doubt the impact of the blast wave on the cloud layers. They seemed, I believe, before the red ball foul started to flatten out.
When I thought it was soon time for the blast to arrive, I sat on the ground, still facing the explosion, and put my fingers in my ears. Despite that, the report was quite respectable and was followed by a long rumbling, not quite like thunder but more regular, like massive noisy wagons running around in the hills.”
Source: Foreign Relations of the United States, Potsdam, vol. 2 (Washington: USGPO, 1960), p. 1371. Reprinted in Philip L. Cantelon, Richard G. Hewlett, and Robert C. Williams, The American Atom: A Documentary History of Nuclear Policies from the Discovery of Fission to the Present, 2nd ed. (Philadelphia: University of Pennsylvania Press, 1991).