FELL TO EARTH IN SIBERIA, RUSSIA IN 1947

Sikhote-Alin is responsible for one of the largest meteorite showers in recorded history. After breaking off from its parent body 320 million years ago, the 70-metric-ton iron mass wandered through interplanetary space until it encountered the Earth. On 12 February 1947 a fireball, brighter than the Sun, exploded at an altitude of about 6 km over Eastern Siberia. Sonic booms were heard at distances up to 300 km from the impact point. On the ground, chimneys collapsed, windows shattered and trees were uprooted. A 33-km-long smoke trail persisted for several hours in the atmosphere after the meteorite struck the ground. Iron fragments were scattered over an elliptical area of 1.6 square kilometres. Many of the fragments penetrated the soil, producing impact holes as large as 26 meters; about 200 such holes have been catalogued. Polished and etched slabs of Sikhote-Alin reveal a very coarse “Widmanstätten” pattern, a product of very slow cooling in the metal core of a differentiated asteroid. A famous painting of the event by artist and eye-witness P. I. Medvedev was reproduced as a postage stamp issued by the Soviet government in 1957 to commemorate the tenth anniversary of the meteorite fall.