It looks like some kind of sci-fi blob from outer space, but it’s actually a high-speed photograph of a nuclear explosion. It was captured less than 1 millisecond after the detonation using a rapatronic camera, which is capable of exposure times as brief as 10 nanoseconds (one nanosecond is one billionth of a second). The photograph was shot from roughly 7 miles away during the Tumbler-Snapper tests in Nevada (1952). The fireball is roughly 20 meters in diameter, and three times hotter than the surface of the sun. The spikes at the bottom of the fireball are known as the rope trick effect.
Colorized photograph: http://i.imgur.com/D24uT.jpg