Thumbprinted Sikhote-Alin sample
|Structural classification||Octahedrite, coarsest|
|Composition||93% Fe, 5.9% Ni, 0.42% Co, 0.46% P, 0.28% S|
|Region||Far Eastern Federal District|
|Fall date||February 12, 1947|
|TKW||>28 tonnes (31 short tons) (est. 70 metric tons )|
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.An estimated 70 tonnes (metric tons) of material survived the fiery passage through the atmosphere and reached the Earth.
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 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.
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.
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 (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.
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.
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.
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, 1957the 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.
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.
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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.
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.
A meteoroid is a small rocky or metallic body in outer space.
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.
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).
Krinov had estimated the post-atmospheric mass of the meteoroid at some 23,000 kg (51,000 lb).
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. Fragments of the meteorite were also driven into the surrounding trees.
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.
Specimens of the Sikhote-Alin Meteorite are basically of two types:
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.
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.
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.
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.
The Tunguska event was a large explosion that occurred near the Stony Tunguska River in Yeniseysk Governorate, Russia, on the morning of 30 June 1908 (NS). The explosion over the sparsely populated Eastern Siberian Taiga flattened 2,000 square kilometres of forest, yet caused no known human casualties. The explosion is generally attributed to the air burst of a meteor. It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres rather than to have hit the surface of the Earth.
An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, though atmospheres mitigate many surface impacts through atmospheric entry. Impact craters and structures are dominant landforms on many of the Solar System's solid objects and present the strongest empirical evidence for their frequency and scale.
The Campo del Cielo refers to a group of iron meteorites or to the area where they were found. This area is situated on the border between the provinces of Chaco and Santiago del Estero, 1,000 kilometers (620 mi) northwest of Buenos Aires, Argentina. The crater field covers an area of 3 by 18.5 kilometres and contains at least 26 craters, the largest being 115 by 91 metres.
The pallasites are a class of stony–iron meteorite.
Pultusk is an H5 ordinary chondrite meteorite which fell on 30 January 1868 in Poland. The event has been known as the stony meteorite shower with the largest number of pieces yet recorded in history. Made up of rocky debris, it consists of pyroxene or olivine chondrules deployed in mass plagioclase, there being also kamacite.
Seymchan is a pallasite meteorite found in the dry bed of the river Hekandue, a left tributary of river Jasačnaja in the Magadan district, Russia, near the settlement of Seymchan, in June 1967.
Buzzard Coulee is the collective name of the meteorites fallen on November 20, 2008 over Saskatchewan, Canada.
Neuschwanstein was an enstatite chondrite meteorite that fell to Earth on 6 April 2002 at 22:20:18 GMT near Neuschwanstein Castle, Bavaria, at the Germany–Austria border.
The Muonionalusta is a meteorite classified as fine octahedrite, type IVA (Of) which impacted in northern Scandinavia, west of the border between Sweden and Finland, about one million years BCE.
The Sutter's Mill meteorite is a carbonaceous chondrite which entered the Earth's atmosphere and broke up at about 07:51 Pacific time on April 22, 2012, with fragments landing in the United States. The name comes from the Sutter's Mill, a California Gold Rush site, near which some pieces were recovered. This was the largest meteoroid impact over land since asteroid 2008 TC3. Meteor astronomer Peter Jenniskens assigned SM numbers to each meteorite, with the documented find location preserving information about where a given meteorite was located in the impacting meteoroid. As of May 2014, 79 fragments had been publicly documented with a find location. The largest (SM53) weighs 205 grams (7.2 oz), and the second largest (SM50) weighs 42 grams (1.5 oz).
IIAB meteorites are a group of iron meteorites. Their structural classification ranges from hexahedrites to octahedrites. IIABs have the lowest concentration of nickel of all iron meteorite groups. All iron meteorites are derived from the metallic planetary cores of their respective parent bodies, but in the case of the IIABs the metallic magma separated to form not only this meteorite group but also the IIG group.
The Chelyabinsk meteor was a superbolide caused by an approximately 20 m (66 ft) near-Earth asteroid that entered Earth's atmosphere over Russia on 15 February 2013 at about 09:20 YEKT, with a speed of 19.16 ± 0.15 kilometres per second. It quickly became a brilliant superbolide meteor over the southern Ural region. The light from the meteor was brighter than the Sun, visible up to 100 km (62 mi) away. It was observed over a wide area of the region and in neighbouring republics. Some eyewitnesses also felt intense heat from the fireball.
The Chelyabinsk meteorite is the fragmented remains of the large Chelyabinsk meteor of 15 February 2013 which reached the ground after the meteor's passage through the atmosphere. The descent of the meteor, visible as a brilliant superbolide in the morning sky, caused a series of shock waves that shattered windows, damaged approximately 7,200 buildings and left 1,500 people injured. The resulting fragments were scattered over a wide area.
2018 LA, also known as ZLAF9B2, was a small Apollo near-Earth asteroid approximately 2.6–3.8 m (9–12 ft) in diameter that impacted Earth at roughly 16:44 UTC on 2 June 2018 near the border of Botswana and South Africa. It was discovered only 8 hours prior by the Mount Lemmon Survey, and based on an hour and a half of observations, it was calculated to have a roughly 85% chance of impacting Earth, likely somewhere between Australia and Madagascar. Hours later, a report arrived to the American Meteor Society that an observer from Botswana had seen a bright fireball. After the impact, the Asteroid Terrestrial-impact Last Alert System (ATLAS) released observations roughly 2 hours after the other reported observations which confirmed that the asteroid had indeed impacted Earth on a grazing path and near the location of the fireball. A preliminary analysis of the pre-impact evolution of this meteoroid suggests that it may be part of a dynamical grouping.
Group lIB. 5.90% Ni, 0.42% Co, 0.46% P, 0.28% S, 52 ppm Ga, 161 ppm Ge , 0.03 ppm Jr.
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