104 years ago today, June 30th 1908 at 7:14 a.m., an enormous explosion took place near the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia. It is believed to have been caused by the air burst of a large meteoroid or comet fragment several kilometers above the Earth’s surface. The object is roughly estimated to have been about 100 meters in diameter, making it the largest impact in recorded history, and the only large impact in the modern era with firsthand eyewitness accounts. It is known as the Tunguska Event.