Sikhote-Alin meteorite

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Sikhote-Alin

SikhoteAlinMeteorite.jpg

Thumbprinted Sikhote-Alin sample
Type Iron
Structural classification Octahedrite, coarsest
Group IIAB
Composition 93% Fe, 5.9% Ni, 0.42% Co, 0.46% P, 0.28% S
Country Russia
Region

Sikhote-Alin Mountains, Primorsky Krai,

Far Eastern Federal District
Coordinates 46°09′36″N134°39′12″E / 46.16000°N 134.65333°E / 46.16000; 134.65333 Coordinates: 46°09′36″N134°39′12″E / 46.16000°N 134.65333°E / 46.16000; 134.65333 [1]
Observed fall Yes
Fall date February 12, 1947
TKW >28 tonnes (31 short tons) [1] (est. 70 metric tons [2] )
Strewn field Yes
Commons-logo.svg Related media on Wikimedia Commons

An iron meteorite fell on the Sikhote-Alin Mountains, in southeastern Russia, in 1947. Though large iron meteorite falls had been witnessed previously and fragments recovered, never before in recorded history had a fall of this magnitude been observed. [3] An estimated 70 tonnes (metric tons) of material survived the fiery passage through the atmosphere and reached the Earth. [2]

Iron meteorite meteorite composed of iron-nickel alloy called meteoric iron

Iron meteorites are meteorites that consist overwhelmingly of an iron–nickel alloy known as meteoric iron that usually consists of two mineral phases: kamacite and taenite. Iron meteorites originate from cores of planetesimals.

Recorded history historical narrative based on a written record or other documented communication

Recorded history or written history is a historical narrative based on a written record or other documented communication. It contrasts with other narratives of the past, such as mythological, oral or archeological traditions. For broader world history, recorded history begins with the accounts of the ancient world around the 4th millennium BC, and coincides with the invention of writing. For some geographic regions or cultures, written history is limited to a relatively recent period in human history because of the limited use of written records. Moreover, human cultures do not always record all of the information relevant to later historians, such as the full impact of natural disasters or the names of individuals; thus, recorded history for particular types of information is limited based on the types of records kept. Because of this, recorded history in different contexts may refer to different periods of time depending on the topic.

Tonne metric unit of mass

The tonne, commonly referred to as the metric ton in the United States, is a non-SI metric unit of mass equal to 1,000 kilograms; or one megagram (Mg); it is equivalent to approximately 2,204.6 pounds, 1.102 short tons (US) or 0.984 long tons (UK). Although not part of the SI, the tonne is accepted for use with SI units and prefixes by the International Committee for Weights and Measures.

Contents

Impact

The 10th anniversary stamp. It reproduces a painting by P. J. Medvedev. Sikhote-Alin stamp 1957.jpg
The 10th anniversary stamp. It reproduces a painting by P. J. Medvedev.

At around 10:30 on 12 February 1947, eyewitnesses in the Sikhote-Alin Mountains, Primorye, Soviet Union, observed a large bolide brighter than the sun that came out of the north and descended at an angle of about 41 degrees. The bright flash and the deafening sound of the fall were observed for 300 kilometres (190 mi) around the point of impact not far from Luchegorsk and approximately 440 km (270 mi) northeast of Vladivostok. A smoke trail, estimated at 32 km (20 mi) long, remained in the sky for several hours.

Primorsky Krai First-level administrative division of Russia

Primorsky Krai (Russian: Примо́рский край, tr.Primorsky kray, IPA: [prʲɪˈmorskʲɪj kraj] is a federal subject of Russia, located in the Far East region of the country and is a part of the Far Eastern Federal District. The city of Vladivostok is the administrative center of the krai, as well as the largest city in the Russian Far East. The krai has the largest economy among the federal subjects in the Russian Far East, and a population of 1,956,497 as of the 2010 Census.

Bolide extremely bright meteor that often explodes in the atmosphere

A bolide is an extremely bright meteor, especially one that explodes in the atmosphere. In astronomy, it refers to a fireball about as bright as the full moon, and it is generally considered a synonym for a fireball. In geology, a bolide is a very large impactor.

Sun Star at the centre of the Solar System

The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, or 109 times that of Earth, and its mass is about 330,000 times that of Earth. It accounts for about 99.86% of the total mass of the Solar System. Roughly three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.

As the meteor, traveling at a speed of about 14 km/s (8.7 mi/s), entered the atmosphere, it began to break apart, and the fragments fell together. At an altitude of about 5.6 km (3.5 mi), the largest mass apparently broke up in a violent explosion called an air burst.

Air burst

An air burst or airburst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor-piercing explosion. The principal military advantage of an air burst over a ground burst is that the energy from the explosion is distributed more evenly over a wider area; however, the peak energy is lower at ground zero.

On November 20, 1957 [4] the Soviet Union issued a stamp for the 10th anniversary of the Sikhote-Alin meteorite shower. It reproduces a painting by P. I. Medvedev, a Soviet artist who witnessed the fall: he was sitting in his window starting a sketch when the fireball appeared, so he immediately began drawing what he saw. [5]

Soviet Union 1922–1991 country in Europe and Asia

The Soviet Union,, officially the Union of Soviet Socialist Republics (USSR), was a socialist state in Eurasia that existed from 30 December 1922 to 26 December 1991. Nominally a union of multiple national Soviet republics, its government and economy were highly centralized. The country was a one-party state, governed by the Communist Party with Moscow as its capital in its largest republic, the Russian Soviet Federative Socialist Republic. Other major urban centres were Leningrad, Kiev, Minsk, Alma-Ata, and Novosibirsk.

Orbit

Because the meteor fell during daytime, it was observed by many eyewitnesses. Evaluation of this observational data allowed V. G. Fesenkov, then chairman of the meteorite committee of the USSR Academy of Science, to estimate the meteoroid's orbit before it encountered the Earth. This orbit was ellipse-shaped, with its point of greatest distance from the sun situated within the asteroid belt, similar to many other small bodies crossing the orbit of the Earth. Such an orbit was probably created by collisions within the asteroid belt.

Russian Academy of Sciences academy of sciences

The Russian Academy of Sciences consists of the national academy of Russia; a network of scientific research institutes from across the Russian Federation; and additional scientific and social units such as libraries, publishing units, and hospitals.

Meteoroid sand- to boulder-sized particle of debris in the Solar System

A meteoroid is a small rocky or metallic body in outer space.

Orbit gravitationally curved path of an object around a point in outer space; circular or elliptical path of one object around another object

In physics, an orbit is the gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet. Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory. To a close approximation, planets and satellites follow elliptic orbits, with the central mass being orbited at a focal point of the ellipse, as described by Kepler's laws of planetary motion.

Size

Sikhote-Alin is a massive fall with the overall size of the meteoroid estimated at approximately 90,000 kg (200,000 lb). A more recent estimate by Tsvetkov (and others) puts the mass at around 100,000 kg (220,000 lb). [6]

Krinov had estimated the post-atmospheric mass of the meteoroid at some 23,000 kg (51,000 lb).

Strewn field and craters

The strewn field for this meteorite covered an elliptical area of about 1.3 km2 (0.50 sq mi). Some of the fragments made impact craters, the largest of which was about 26 m (85 ft) across and 6 m (20 ft) deep. [7] Fragments of the meteorite were also driven into the surrounding trees.

Composition and classification

Section Sikhote alin.jpg
Section

The Sikhote-Alin meteorite is classified as an iron meteorite belonging to the meteorite group IIAB and with a coarse octahedrite structure. It is composed of approximately 93% iron, 5.9% nickel, 0.42% cobalt, 0.46% phosphorus, and 0.28% sulfur, with trace amounts of germanium and iridium. Minerals present include taenite, plessite, troilite, chromite, kamacite, and schreibersite. [8]

Specimens

Specimens of the Sikhote-Alin Meteorite are basically of two types: [6]

  1. individual, thumbprinted or regmaglypted specimens, showing fusion crust and signs of atmospheric ablation
  2. shrapnel or fragmented specimens, sharp-edged pieces of torn metal showing evidence of violent fragmentation

The first type probably broke off the main object early in the descent. These pieces are characterized by regmaglypts (cavities resembling thumb prints) in the surface of each specimen. The second type are fragments which were either torn apart during the atmospheric explosions or blasted apart upon impact on the frozen ground. Most were probably the result of the explosion at 5.6 km (3.5 mi) altitude.

A large specimen is on display in Moscow. Many other specimens are held by Russian Academy of Science and a great number of smaller specimens have made their way into the collector's market.

See also

Related Research Articles

Impact crater Circular depression on a solid astronomical body formed by a hypervelocity impact of a smaller object

An impact crater is an approximately circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Although Meteor Crater is perhaps the best-known example of a small impact crater on Earth, impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins.

Meteorite piece of solid matter from outer space that has hit the earth

A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate that energy. It then becomes a meteor and forms a fireball, also known as a shooting star or falling star; astronomers call the brightest examples "bolides". Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater.

Near-Earth object Solar System object whose orbit brings it into proximity with Earth

A near-Earth object (NEO) is any small Solar System body whose orbit brings it to proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). If a NEO's orbit crosses the Earth's and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but a small fraction are comets.

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References

  1. 1 2 Meteoritical Bulletin Database: Sikhote-Alin. Archived from the original on 2012-01-30.
  2. 1 2 Norton, O. Richard; Chitwood, Lawrence A. (2008). Field Guide to Meteors and Meteorites. London: Springer-Verlag. p. 47. ISBN   9781848001572.
  3. Norton, O. Richard (1998). Rocks From Space. Missoula, Montana: Mountain Press. p. 103. ISBN   0878423028.
  4. Burns, Philip R. "Pib". "Meteorite Stamps and Coins". Archived from the original on 2000-01-21.
  5. "Sikhote Alin". Planetarium de Montreal. Archived from the original on 2006-05-21.
  6. 1 2 Gallant, Roy (February 1996). "Sikhote-Alin Revisited". Meteorite Magazine. Arkansas Center for Space and Planetary Sciences, University of Arkansas. Archived from the original on 2010-06-12.
  7. "Sikhote-Alin". Earth Impact Database . University of New Brunswick . Retrieved 2009-08-19.[ dead link ]
  8. Buchwald, Vagn F. (1975). HANDBOOK OF IRON METEORITES Their History, Distribution, Composition and Structure. https://evols.library.manoa.hawaii.edu/handle/10524/36040: University of California Press. pp. Vol 3, Pages 1123–1130. Group lIB. 5.90% Ni, 0.42% Co, 0.46% P, 0.28% S, 52 ppm Ga, 161 ppm Ge , 0.03 ppm Jr.