On This Day (June 30)

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In 1908, A massive explosion occurred near the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia, knocking over 80 million trees over 2,150 square kilometres (830 sq mi).

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 (3–6 miles) 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.