On 30 June 1908, shortly after 7 a.m., residents of the hills northwest of Lake Baikal in Siberia saw a light in the sky, nearly as bright as the sun. This was followed by a flash of light, a sound like artillery fire, and a shockwave that knocked people off their feet and shattered windows. Something had exploded in the forest near the Podkamennaya Tunguska River, with energy equivalent to 10-15 megatons of TNT (However, some recent experiments indicate that the blast may have actually been smaller, at "only" 3-5 megatons). Sub-Trope of Historical In-Joke. Compare Roswell That Ends Well.