It is one of the most uninhabitable places in the world.

The Russian area of Tunguska consists of enormous bogs and thick forests. The mosquitoes are vicious and the temperatures can drop well below freezing in the winter and soar to near 100 degrees in the summer. There are very few villages in the area, and nomadic reindeer herders move slowly along the landscape.

One wouldn't really expect something extraordinary to happen here, but on the morning of June 30, 1908, the world changed in a remarkable way.

A…