clipped from: www.universetoday.com   
The 1908 Tunguska event has always been mysterious and intriguing because no one has been able to fully explain the explosion that leveled 830 square miles of Siberian forest.

Fallen trees from the Tunguska Event in 1908.

the latest research has concluded that the Tunguska explosion was almost certainly caused by a comet entering the Earth’s atmosphere.

Following the Tunguska Event, the night skies shone brightly for several days across Europe, particularly Great Britain — more than 3,000 miles away.
clipped from: www.astronomynow.com   

3D reconstruction of Lake Cheko based on real topographic data. The water level has been placed 40 metres below the actual level to show the main morphological features of the lake.
clipped from: www.youtube.com