Sikhote-Alin
In 1947 an iron meteoroid shattered over the Russian Far East, raining tonnes of metal and blasting more than 100 craters.
Key facts
- Type
- Iron, IIAB (coarsest octahedrite)
- Fell or found
- Fell (witnessed)
- Year
- 1947 (12 February)
- Country
- Russia
- Mass
- about 23 tonnes recovered
- Official name
- Sikhote-Alin
On the morning of 12 February 1947, people in the Sikhote-Alin mountains of the Russian Far East saw a fireball brighter than the Sun streak across the winter sky. Loud bangs rolled across the forested hills, and a huge trail of smoke and dust hung in the sky for hours. An iron meteoroid, a solid chunk of metal from space, had broken apart in the atmosphere. Its fragments rained down on the snowy forest, creating the largest observed fall of iron meteorites in recorded history.
A painter's eyewitness record
In the town of Iman, now called Dalnerechensk, the artist P. I. Medvedev saw the fireball pass and quickly sketched it and later turned it into a painting. In 1957, for the tenth anniversary of the fall, the Soviet Union issued a postage stamp based on it, one of the few stamps ever to show a real meteorite fall.
Craters in the snow
Scientists from the Soviet Academy of Sciences, including the meteorite specialist Evgeny Krinov, soon organised expeditions to the remote site. They found a strewn field, the area where fragments landed, covering more than a square kilometre of forest, with over 100 craters and holes. The largest crater was about 26 metres across. Trees had been snapped and stripped, and metal shards were embedded in the trunks. Over several expeditions about 23 tonnes of meteorite were recovered. The largest single piece weighs about 1,745 kilograms and is displayed in Moscow. The meteoroid before it entered the atmosphere is thought to have weighed several tens of tonnes, as much was lost to the intense heating of entry.
Two kinds of fragment
Sikhote-Alin specimens come in two very different forms. Some pieces separated high in the atmosphere and flew on alone. They are called individuals, and their surfaces are covered in smooth thumbprint-like hollows called regmaglypts, sculpted as their outer layers melted and streamed away. Others smashed into the frozen ground at high speed and were torn apart into jagged, twisted shrapnel, which looks more like the remains of an explosion than a rock from space. Both kinds are widely held in museum collections. Many small individuals still carry patches of their original fusion crust, and some show fine flow lines where molten metal streamed backwards across the surface during flight.
What the metal tells us
Sikhote-Alin is an iron meteorite of the IIAB group, made of about 94 per cent iron and 6 per cent nickel, with smaller amounts of cobalt and other elements. It is classed as a 'coarsest octahedrite' because its interlocking metal crystals, revealed when a cut face is etched in the laboratory, are unusually broad. Like other irons, it probably comes from the core of an asteroid that melted early in the Solar System's history and was later shattered by collisions. The orbit worked out from eyewitness reports suggests it came from the asteroid belt between Mars and Jupiter.
Why it matters
Sikhote-Alin is a textbook example of how a large iron body behaves when it meets the atmosphere: how it breaks up, how fragments spread across a strewn field, and how pieces of different sizes carve out craters. Because the fall was witnessed and the site was studied quickly, it gave scientists a uniquely detailed picture of a modern crater-forming event. Its regmaglypted individuals are among the most recognisable meteorites anywhere, often used to show students what a freshly fallen iron should look like.
The area is now protected, and pieces circulating today were mostly recovered decades ago. If you ever handle one, notice how heavy it feels for its size, and run a finger over the thumbprints: they were melted into the metal in just a few seconds of fiery flight.
Did you know?
An artist's painting of the fireball appeared on a Soviet postage stamp in 1957, ten years after the fall.
The largest crater formed by the fall was about 26 metres across, with more than 100 craters and holes in total.
The biggest single piece weighs about 1,745 kilograms.