10. The Tunguska Event
In 1908, a colossal explosion rocked Siberia, flattening more than 2,000 square kilometers of remote forest. The Tunguska Event is widely thought to have resulted from a meteor or comet exploding in the atmosphere, yet the absence of an impact crater leaves room for uncertainty. Some details, including eyewitness reports and the explosion’s unusual characteristics, remain unexplained. This century-old mystery still captivates scientists and the public alike. For more, visit NASA Earth Observatory.