Mystery in the Forest: What Happened at Tunguska?

On the morning of June 30, 1908, a sudden flash brighter than the sun lit up the sky above a remote forest in Siberia, Russia. Seconds later, a tremendous shock wave ripped across the landscape near the Podkamennaya Tunguska River. The blast leveled an estimated eighty million trees across more than eight hundred square miles, flattening the pine forest in a giant, outward pattern. Yet when scientists finally reached the isolated region years later, they found a puzzling clue: there was no giant impact crater in the ground.

Today, scientists understand that the explosion was an airburst caused by a cosmic traveler. Instead of slamming directly into the soil, a stony space rock entered Earth's thick atmosphere at tens of thousands of miles per hour. As it plunged downward, the air in front of the rock compressed rapidly, generating intense friction and extreme heat. Five to six miles above the ground, the tremendous pressure overcame the rock, causing it to detonate violently in midair. This powerful atmospheric explosion explained why millions of trees fell while leaving the soil beneath unbroken by a crater.