Tunguska Event: The 1908 Siberian Blast That Left No Crater

In 1908 an explosion over Siberia flattened some 80 million trees across 2,000 square kilometers and left no crater.

On June 30, 1908, an explosion in the air over Siberia's Podkamennaya Tunguska River flattened about 80 million trees. Most scientists think a stony asteroid or comet fragment exploded several kilometers up.

On the morning of June 30, 1908, a massive explosion occurred in the air over the Podkamennaya Tunguska River in central Siberia. Witnesses saw a bluish-white column of light moving across the sky, followed by a flash and a shock wave. At the trading post of Vanavara, about 65 kilometers away, a man named Semenov later said he was thrown from his porch and felt heat as if his shirt were on fire.

The blast flattened an estimated 80 million trees over about 2,150 square kilometers, laying them out in a radial pattern pointing away from the center. At ground zero, trees were left standing but stripped of branches. Seismographs across Eurasia recorded the shock, and for several nights afterward the skies over Europe and Asia glowed so brightly that people could read outdoors at midnight.

Because the area was remote, the first scientific expedition, led by Leonid Kulik, did not reach it until 1927. To his surprise, there was no crater. Most scientists now think a stony asteroid or a comet fragment tens of meters across exploded at an altitude of roughly 5 to 10 kilometers, releasing energy estimated at several megatons of TNT.

The lack of a crater and meteorite fragments invited wild theories, from a crashed alien spacecraft to antimatter and a mini black hole. Tunguska is now a key case study for planetary defense, and a useful reference point for reading ancient reports of fire from the sky. Its energy is often compared to hundreds of Hiroshima bombs.