On the morning of June 30, 1908, people throughout the world were minding their own business. Then, a great fireball streaked across the sky over a remote part of Asia. Soon after a titanic explosion rocked Siberia. The explosion was heard for great distances, and it was even detected by its overpressure at sites around the world as the pressure wave circled the globe more than once. Debris in the atmosphere turned days and nights into twilight across the northern hemisphere for weeks...