On June 30, 1908, a giant fireball exploded in the Siberian sky with a force a thousand times greater than the Hiroshima bomb, decimating 1,000 square miles of forest. What caused the apocalyptic fire in the sky?On June 30, 1908, a giant fireball exploded in the Siberian sky with a force a thousand times greater than the Hiroshima bomb, decimating 1,000 square miles of forest. What caused the apocalyptic fire in the sky?