This day in Russian history and the History of the world.

June 30

June 30, 1908: The Tunguska Event took place.

It was powerful explosion that occurred over the so-called Southern swamp, a small morass not far from the Podkamennaya (Lower Stony) Tunguska River in what is now Krasnoyarsk Krai of Russia.

Although the cause of the explosion is the subject of debate, it is commonly believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 5-10 kilometres (3.1-6.2 mi) above the Earth's surface.

Different studies have yielded varying estimates of the object's size, with general agreement that it was a few tens of metres across.

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