A sun-bright fireball
On February 12, 1947, at 10:38 a.m. local time, a fireball brighter than the sun tore across the sky over the Sikhote-Alin Mountains in eastern Siberia. Eyewitnesses up to 300 kilometers away saw the spectacle and heard its roar. A Soviet artist named P. J. Medvedev was looking out a window and immediately began to sketch the event; his painting was used on a 10th-anniversary commemorative stamp. The object, an iron meteoroid with an estimated pre-atmospheric mass of around 100 metric tons, entered the atmosphere at approximately 14 kilometers per second (about 31,000 miles per hour).
As it descended at a 41-degree angle, it left a smoke and dust trail 32 kilometers long that lingered in the sky for several hours. At an altitude of about 5.6 kilometers, the main body of the meteoroid violently exploded in an air burst. This low-altitude explosion sent a shower of metallic fragments raining down onto the remote, snow-covered taiga. It was the largest witnessed meteorite fall in recorded history. The meteoroid itself likely originated in the asteroid belt between Mars and Jupiter.
A forest of craters
The fragments struck the earth across an elliptical area of about 1.3 square kilometers. The impact zone was like a bombing range, with more than 120 craters and impact pits gouged into the frozen ground. The largest of these craters measured 26 meters across and 6 meters deep. Trees in the impact zone were shredded and knocked down, with many still lying in radial patterns extending from the larger craters. Jagged pieces of the meteorite, some weighing up to 45 kilograms, were found embedded in the trunks of standing trees.
The total mass of the material that reached the ground is estimated to be between 23 and 70 metric tons. Expeditions organized by the Russian Academy of Sciences between 1947 and 1950 recovered over 8,500 specimens totaling more than 23 tons of material. The largest single fragment found weighs 1,745 kilograms and is now on display in Moscow. The meteorite is classified as a IIAB coarsest octahedrite, composed of approximately 93% iron, 5.9% nickel, and smaller amounts of cobalt, phosphorus, and sulfur.