On June 30, 1908, at around 7:15 am local time, a bright streak tore across the sky over the Podkamennaya Tunguska River in Siberia. Witnesses described a fireball brighter than the Sun, followed by a flash, a thunderous roar and earth-shaking tremors. The shockwave knocked people off their feet, broke windows in distant settlements and sparked awe across the region.