A SIKHOTE-ALIN METEORITE — PRISTINE INDIVIDUAL FROM THE ONE OF THE LARGEST METEORITE SHOWERS IN HUMAN HISTORY

After breaking off its parent asteroid 320 million years ago, a massive iron mass wandered through interplanetary space until a close encounter with Earth on February 12, 1947. A fireball brighter than the Sun was seen to explode at an altitude of about 6 kilometres over eastern Siberia. Sonic booms were heard at distances up to 300 kilometres from the point of impact. Chimneys collapsed, windows shattered and trees were uprooted. A 33-kilometre long smoke trail persisted for several hours in the atmosphere after impact. Iron fragments were scattered over a broad elliptical area. Many of the meteorites penetrated the soil, producing impact craters up to 26 meters across; about 200 such depressions have been catalogued. As evidenced by the regmaglypts (thumbprint-like indentations) blanketing this mass, this meteorite was not part of the massive low altitude explosion. Instead, this specimen broke off at a much higher altitude, providing sufficient time for frictional heating with the atmosphere to form the artifacts of atmospheric heating now seen.