100 years ago today, a small chunk of rock or possibly ice was lazily making its way across the inner solar system when a large, blue-green planet got in its way. Traveling roughly westward, it entered the Earth’s atmosphere moving at tens of thousands kilometers per hour. Compressed and battered by tremendous forces, the object got about 5 – 10 kilometers from the ground before it succumbed, exploding like a gigantic multi-megaton bomb.
The air blast flattened trees for hundreds of square kilometers. The ground shook, witnesses felt the hellish heat from kilometers away, and the shock wave circled the world. It happened over the remote Podkammenaya Tungus river, a swampy region in Russia; had it happened over Moscow a million people might have died within minutes.
Now known as the Tunguska Event, it stands today as a shocking reminder that we live in a cosmic shooting gallery, and the Earth sits in the crosshairs of many objects.