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126-637: Wolfe Creek Crater is a well-preserved meteorite impact crater ( astrobleme ) in Western Australia . It is accessed via the Tanami Road 150 km (93 mi) south of the town of Halls Creek . The crater is central to the Wolfe Creek Meteorite Crater National Park . The crater averages about 875 metres (2,871 ft) in diameter, 60 metres (200 ft) from rim to present crater floor. It

252-633: A 1 km (0.62 mi) diameter strike Earth every 500,000 years on average. Large collisions – with 5 km (3 mi) objects – happen approximately once every twenty million years. The last known impact of an object of 10 km (6 mi) or more in diameter was at the Cretaceous–Paleogene extinction event 66 million years ago. The energy released by an impactor depends on diameter, density, velocity, and angle. The diameter of most near-Earth asteroids that have not been studied by radar or infrared can generally only be estimated within about

378-573: A 61-kilogram (135 lb) iron meteorite was found in a Sinagua (c. 1100–1200 AD) burial cyst near Camp Verde, Arizona , respectfully wrapped in a feather cloth. A small pallasite was found in a pottery jar in an old burial found at Pojoaque Pueblo , New Mexico. Nininger reports several other such instances, in the Southwest US and elsewhere, such as the discovery of Native American beads of meteoric iron found in Hopewell burial mounds , and

504-493: A Nemesis-style periodicity. An impact event is commonly seen as a scenario that would bring about the end of civilization . In 2000, Discover magazine published a list of 20 possible sudden doomsday scenarios with an impact event listed as the most likely to occur. A joint Pew Research Center / Smithsonian survey from April 21 to 26, 2010 found that 31 percent of Americans believed that an asteroid will collide with Earth by 2050. A majority (61 percent) disagreed. In

630-672: A blend of rock and metal, the stony-iron meteorites . Modern classification of meteorites is complex. The review paper of Krot et al. (2007) summarizes modern meteorite taxonomy. About 86% of the meteorites are chondrites, which are named for the small, round particles they contain. These particles, or chondrules , are composed mostly of silicate minerals that appear to have been melted while they were free-floating objects in space. Certain types of chondrites also contain small amounts of organic matter , including amino acids , and presolar grains . Chondrites are typically about 4.55 billion years old and are thought to represent material from

756-535: A devastating asteroid], but we're not 100 percent certain when." Also in 2018, physicist Stephen Hawking considered in his final book Brief Answers to the Big Questions that an asteroid collision was the biggest threat to the planet. In June 2018, the US National Science and Technology Council warned that America is unprepared for an asteroid impact event, and has developed and released

882-519: A diameter of 20 m (66 ft), and which strike Earth approximately twice every century, produce more powerful airbursts. The 2013 Chelyabinsk meteor was estimated to be about 20 m in diameter with an airburst of around 500 kilotons, an explosion 30 times the Hiroshima bomb impact. Much larger objects may impact the solid earth and create a crater. Objects with a diameter less than 1 m (3.3 ft) are called meteoroids and seldom make it to

1008-444: A diameter of 4 meters (13 ft) enter Earth's atmosphere about once a year. Asteroids with a diameter of 7 meters enter the atmosphere about every 5 years with as much kinetic energy as the atomic bomb dropped on Hiroshima (approximately 16 kilotons of TNT), but the air burst is reduced to just 5 kilotons. These ordinarily explode in the upper atmosphere and most or all of the solids are vaporized . However, asteroids with

1134-530: A factor of two, by basing it on the asteroid's brightness. The density is generally assumed, because the diameter and mass, from which density can be calculated, are also generally estimated. Due to Earth's escape velocity , the minimum impact velocity is 11 km/s with asteroid impacts averaging around 17 km/s on the Earth. The most probable impact angle is 45 degrees. Impact conditions such as asteroid size and speed, but also density and impact angle determine

1260-458: A few centimeters in size that were formed—according to most scientists—by the impacts of large meteorites on Earth's surface. A few researchers have favored tektites originating from the Moon as volcanic ejecta, but this theory has lost much of its support over the last few decades. The diameter of the largest impactor to hit Earth on any given day is likely to be about 40 centimeters (16 inches), in

1386-798: A flat, desert plain about 100 kilometres (62 mi) southeast of Dirj (Daraj), Libya . A few years later, a desert enthusiast saw photographs of meteorites being recovered by scientists in Antarctica, and thought that he had seen similar occurrences in northern Africa . In 1989, he recovered about 100 meteorites from several distinct locations in Libya and Algeria. Over the next several years, he and others who followed found at least 400 more meteorites. The find locations were generally in regions known as regs or hamadas : flat, featureless areas covered only by small pebbles and minor amounts of sand. Dark-colored meteorites can be easily spotted in these places. In

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1512-435: A given year about four metres (13 ft), and in a given century about 20 m (66 ft). These statistics are obtained by the following: Over at least the range from five centimeters (2.0 inches) to roughly 300 meters (980 feet), the rate at which Earth receives meteors obeys a power-law distribution as follows: where N (> D ) is the expected number of objects larger than a diameter of D meters to hit Earth in

1638-628: A group of iron meteorites were found, estimated as dating to 4,000–5,000 years ago. It first came to attention of Spanish authorities in 1576; in 2015, police arrested four alleged smugglers trying to steal more than a ton of protected meteorites. The Henbury craters in Australia (~5,000 years old) and Kaali craters in Estonia (~2,700 years old) were apparently produced by objects that broke up before impact. Whitecourt crater in Alberta, Canada

1764-580: A hypothetical companion star to the Sun called Nemesis periodically disrupting the orbits of comets in the Oort cloud , leading to a large increase in the number of comets reaching the inner Solar System where they might hit Earth. Physicist Adrian Melott and paleontologist Richard Bambach have more recently verified the Raup and Sepkoski finding, but argue that it is not consistent with the characteristics expected of

1890-401: A meteorite shower falls is known as its strewn field . Strewn fields are commonly elliptical in shape, with the major axis parallel to the direction of flight. In most cases, the largest meteorites in a shower are found farthest down-range in the strewn field. Most meteorites are stony meteorites, classed as chondrites and achondrites . Only about 6% of meteorites are iron meteorites or

2016-504: A meteorite that was understood by contemporaries to have fallen to the earth from Jupiter , the principal Roman deity. There are reports that a sacred stone was enshrined at the temple that may have been a meteorite. The Black Stone set into the wall of the Kaaba has often been presumed to be a meteorite, but the little available evidence for this is inconclusive. Some Native Americans treated meteorites as ceremonial objects. In 1915,

2142-512: A radius of a hundred or more kilometers. Whistling and hissing sounds are also sometimes heard but are poorly understood. Following the passage of the fireball, it is not unusual for a dust trail to linger in the atmosphere for several minutes. As meteoroids are heated during atmospheric entry , their surfaces melt and experience ablation . They can be sculpted into various shapes during this process, sometimes resulting in shallow thumbprint-like indentations on their surfaces called regmaglypts . If

2268-554: A rapid rise in commercial collection of meteorites. This process was accelerated when, in 1997, meteorites coming from both the Moon and Mars were found in Libya. By the late 1990s, private meteorite-collecting expeditions had been launched throughout the Sahara. Specimens of the meteorites recovered in this way are still deposited in research collections, but most of the material is sold to private collectors. These expeditions have now brought

2394-1055: A shooting star; astronomers call the brightest examples " bolides ". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater . Meteorites that are recovered after being observed as they transit the atmosphere and impact the Earth are called meteorite falls . All others are known as meteorite finds . Meteorites have traditionally been divided into three broad categories: stony meteorites that are rocks, mainly composed of silicate minerals ; iron meteorites that are largely composed of ferronickel ; and stony-iron meteorites that contain large amounts of both metallic and rocky material. Modern classification schemes divide meteorites into groups according to their structure, chemical and isotopic composition and mineralogy. "Meteorites" less than ~1 mm in diameter are classified as micrometeorites , however micrometeorites differ from meteorites in that they typically melt completely in

2520-568: A significant role in the evolution of the Solar System since its formation. Major impact events have significantly shaped Earth's history , and have been implicated in the formation of the Earth–Moon system . Impact events also appear to have played a significant role in the evolutionary history of life . Impacts may have helped deliver the building blocks for life (the panspermia theory relies on this premise). Impacts have been suggested as

2646-428: A single person, Ivan Wilson. In total, nearly 140 meteorites were found in the region since 1967. In the area of the finds, the ground was originally covered by a shallow, loose soil sitting atop a hardpan layer. During the dustbowl era, the loose soil was blown off, leaving any rocks and meteorites that were present stranded on the exposed surface. Beginning in the mid-1960s, amateur meteorite hunters began scouring

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2772-414: A space craft crashed there. Meteorite A meteorite is a rock that originated in outer space and has fallen to the surface of a planet or moon . When the original object enters the atmosphere, various factors such as friction , pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a fireball , also known as

2898-479: A volcanic origin, which has also been proposed as a cause for the iridium enrichment. Further, the chromium isotopic ratios measured in the K-T boundary are similar to the chromium isotopic ratios found in carbonaceous chondrites . Thus a probable candidate for the impactor is a carbonaceous asteroid, but a comet is also possible because comets are assumed to consist of material similar to carbonaceous chondrites. Probably

3024-458: A year. Such events would seem to be spectacularly obvious, but they generally go unnoticed for a number of reasons: the majority of the Earth's surface is covered by water; a good portion of the land surface is uninhabited; and the explosions generally occur at relatively high altitude, resulting in a huge flash and thunderclap but no real damage. Although no human is known to have been killed directly by an impact , over 1000 people were injured by

3150-608: A year. This is based on observations of bright meteors seen from the ground and space, combined with surveys of near-Earth asteroids . Above 300 m (980 ft) in diameter, the predicted rate is somewhat higher, with a 2 km (1.2 mi) asteroid (one teraton TNT equivalent ) every couple of million years – about 10 times as often as the power-law extrapolation would predict. In 2015, NASA scientists reported that complex organic compounds found in DNA and RNA , including uracil , cytosine , and thymine , have been formed in

3276-456: Is 0.4%. Stony-iron meteorites constitute the remaining 1%. They are a mixture of iron-nickel metal and silicate minerals. One type, called pallasites , is thought to have originated in the boundary zone above the core regions where iron meteorites originated. The other major type of stony-iron meteorites is the mesosiderites . Tektites (from Greek tektos , molten) are not themselves meteorites, but are rather natural glass objects up to

3402-516: Is a meteorite collected after its arrival was observed by people or automated devices. Any other meteorite is called a "meteorite find". There are more than 1,100 documented falls listed in widely used databases, most of which have specimens in modern collections. As of January 2019 , the Meteoritical Bulletin Database had 1,180 confirmed falls. Most meteorite falls are collected on the basis of eyewitness accounts of

3528-627: Is also coincidental to some of the earliest evidence of life on Earth, fossilized Stromatolites . Evidence for at least 4 impact events have been found in spherule layers (dubbed S1 through S8) from the Barberton Greenstone Belt in South Africa, spanning around 3.5-3.2 billion years ago. The sites of the impacts are thought to have been distant from the location of the belt. The impactors that generated these events are thought to have been much larger than those that created

3654-413: Is currently prohibited by national law, but a number of international hunters continue to remove specimens now deemed national treasures. This new law provoked a small international incident , as its implementation preceded any public notification of such a law, resulting in the prolonged imprisonment of a large group of meteorite hunters, primarily from Russia, but whose party also consisted of members from

3780-410: Is estimated that the meteorite that formed it was about 15 metres (49 ft) in diameter and had a mass of about 14,000 tonnes. For many years it was thought to have been created around 300,000 years ago, but in 2019, following investigations by researchers from Portsmouth University together with Australian and US researchers, it is now estimated to be less than 120,000 years old, placing the event in

3906-520: Is estimated to be between 1,080 and 1,130 years old. The crater is approximately 36 m (118 ft) in diameter and 9 m (30 ft) deep, is heavily forested and was discovered in 2007 when a metal detector revealed fragments of meteoric iron scattered around the area. A Chinese record states that 10,000 people were killed in the 1490 Qingyang event with the deaths caused by a hail of "falling stones"; some astronomers hypothesize that this may describe an actual meteorite fall, although they find

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4032-459: Is no definitive evidence of impacts leading to the three other major mass extinctions. In 1980, physicist Luis Alvarez ; his son, geologist Walter Alvarez ; and nuclear chemists Frank Asaro and Helen V. Michael from the University of California, Berkeley discovered unusually high concentrations of iridium in a specific layer of rock strata in the Earth's crust. Iridium is an element that

4158-499: Is normally associated with large impact events or atomic bomb explosions, has also been found in the same layer at more than 30 sites. Soot and ash at levels tens of thousands times normal levels were found with the above. Anomalies in chromium isotopic ratios found within the K-T boundary layer strongly support the impact theory. Chromium isotopic ratios are homogeneous within the earth, and therefore these isotopic anomalies exclude

4284-518: Is now Western Australia ), dated at more than 2.2 billion years ago with the impactor estimated to be around 7 kilometres (4.3 mi) wide. It is believed that, at this time, the Earth was mostly or completely frozen, commonly called the Huronian glaciation . The Vredefort impact event , which occurred around 2 billion years ago in Kaapvaal Craton (what is now South Africa ), caused

4410-551: Is rare on Earth but relatively abundant in many meteorites. From the amount and distribution of iridium present in the 65-million-year-old "iridium layer", the Alvarez team later estimated that an asteroid of 10 to 14 km (6 to 9 mi) must have collided with Earth. This iridium layer at the Cretaceous–Paleogene boundary has been found worldwide at 100 different sites. Multidirectionally shocked quartz (coesite), which

4536-410: The Cretaceous–Paleogene extinction event . Small objects frequently collide with Earth. There is an inverse relationship between the size of the object and the frequency of such events. The lunar cratering record shows that the frequency of impacts decreases as approximately the cube of the resulting crater's diameter, which is on average proportional to the diameter of the impactor. Asteroids with

4662-475: The Deccan Traps . While numerous impact craters have been confirmed on land or in the shallow seas over continental shelves , no impact craters in the deep ocean have been widely accepted by the scientific community. Impacts of projectiles as large as one km in diameter are generally thought to explode before reaching the sea floor, but it is unknown what would happen if a much larger impactor struck

4788-613: The Dhofar and Al Wusta regions of Oman, south of the sandy deserts of the Rub' al Khali , had yielded about 5,000 meteorites as of mid-2009. Included among these are a large number of lunar and Martian meteorites, making Oman a particularly important area both for scientists and collectors. Early expeditions to Oman were mainly done by commercial meteorite dealers, however, international teams of Omani and European scientists have also now collected specimens. The recovery of meteorites from Oman

4914-507: The Late Pleistocene . Small numbers of iron meteorites have been found in the vicinity of the crater, as well as larger so-called 'shale-balls', rounded objects made of iron oxide, some weighing as much as 250 kilograms (550 lb). It was brought to the attention of scientists after being spotted during an aerial survey in 1947, investigated on the ground two months later, and reported in publication in 1949. The European name for

5040-709: The Lonar crater lake in India, approximately 52,000 years old (though a study published in 2010 gives a much greater age), which now has a flourishing semi-tropical jungle around it. The Rio Cuarto craters in Argentina were produced approximately 10,000 years ago, at the beginning of the Holocene. If proved to be impact craters, they would be the first impact of the Holocene. The Campo del Cielo ("Field of Heaven") refers to an area bordering Argentina's Chaco Province where

5166-699: The asteroid belt that never coalesced into large bodies. Like comets , chondritic asteroids are some of the oldest and most primitive materials in the Solar System . Chondrites are often considered to be "the building blocks of the planets". About 8% of the meteorites are achondrites (meaning they do not contain chondrules), some of which are similar to terrestrial igneous rocks . Most achondrites are also ancient rocks, and are thought to represent crustal material of differentiated planetesimals. One large family of achondrites (the HED meteorites ) may have originated on

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5292-412: The dynamo mechanism at a planet's core responsible for maintaining the magnetic field of the planet , and may have contributed to Mars' lack of current magnetic field. An impact event may cause a mantle plume ( volcanism ) at the antipodal point of the impact. The Chicxulub impact may have increased volcanism at mid-ocean ridges and has been proposed to have triggered flood basalt volcanism at

5418-422: The genetic code of all life on Earth. These compounds have also occurred spontaneously in laboratory settings emulating conditions in outer space. Until recently, the source of only about 6% of meteorites had been traced to their sources: the Moon, Mars, and asteroid Vesta. Approximately 70% of meteorites found on Earth now appear to originate from break-ups of three asteroids. Most meteorites date from

5544-610: The origin of water on Earth . They have also been implicated in several mass extinctions . The prehistoric Chicxulub impact , 66 million years ago, is believed to not only be the cause of the Cretaceous–Paleogene extinction event but acceleration of the evolution of mammals , leading to their dominance and, in turn, setting in place conditions for the eventual rise of humans . Throughout recorded history, hundreds of Earth impacts (and exploding bolides ) have been reported, with some occurrences causing deaths, injuries, property damage, or other significant localised consequences. One of

5670-416: The same source , a collision that occurred somewhere between Jupiter and Mars. One of these fossil meteorites, dubbed Österplana 065 , appears to represent a distinct type of meteorite that is "extinct" in the sense that it is no longer falling to Earth, the parent body having already been completely depleted from the reservoir of near-Earth objects . A "meteorite fall", also called an "observed fall",

5796-616: The "National Near-Earth Object Preparedness Strategy Action Plan" to better prepare. According to expert testimony in the United States Congress in 2013, NASA would require at least five years of preparation before a mission to intercept an asteroid could be launched. On 26 September 2022, the Double Asteroid Redirection Test demonstrated the deflection of an asteroid. It was the first such experiment to be carried out by humankind and

5922-530: The 10th Japanese Antarctic Research Expedition found nine meteorites on a blue ice field near the Yamato Mountains . With this discovery, came the realization that movement of ice sheets might act to concentrate meteorites in certain areas. After a dozen other specimens were found in the same place in 1973, a Japanese expedition was launched in 1974 dedicated to the search for meteorites. This team recovered nearly 700 meteorites. Shortly thereafter,

6048-737: The American Southwest have been submitted with false find locations, as many finders think it is unwise to publicly share that information for fear of confiscation by the federal government and competition with other hunters at published find sites. Several of the meteorites found recently are currently on display in the Griffith Observatory in Los Angeles, and at UCLA 's Meteorite Gallery. A few meteorites were found in Antarctica between 1912 and 1964. In 1969,

6174-489: The Chelyabinsk meteor airburst event over Russia in 2013. In 2005 it was estimated that the chance of a single person born today dying due to an impact is around 1 in 200,000. The two to four-meter-sized asteroids 2008 TC 3 , 2014 AA , 2018 LA , 2019 MO , 2022 EB5 , and the suspected artificial satellite WT1190F are the only known objects to be detected before impacting the Earth. Impacts have had, during

6300-509: The Cretaceous–Paleogene extinction event, scientists believe that the impactor was a metallic asteroid with a diameter in the order of 1.5 kilometres (0.9 mi). The impact would have had global effects. Artifacts recovered with tektites from the 803,000-year-old Australasian strewnfield event in Asia link a Homo erectus population to a significant meteorite impact and its aftermath. Significant examples of Pleistocene impacts include

6426-452: The Earth are caused by iron meteoroids, which are most easily able to transit the atmosphere intact. Examples of craters caused by iron meteoroids include Barringer Meteor Crater , Odessa Meteor Crater , Wabar craters , and Wolfe Creek crater ; iron meteorites are found in association with all of these craters. In contrast, even relatively large stony or icy bodies such as small comets or asteroids , up to millions of tons, are disrupted in

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6552-612: The Earth in the Sikhote-Alin Mountains , Primorye , Soviet Union. It was during daytime hours and was witnessed by many people, which 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. Sikhote-Alin is a massive fall with the overall size of the meteoroid estimated at 90,000 kg (200,000 lb). A more recent estimate by Tsvetkov (and others) puts

6678-539: The Earth's closest celestial partner, the Moon, astrogeologists have determined that during the last 600 million years, the Earth has been struck by 60 objects of a diameter of 5 km (3 mi) or more. The smallest of these impactors would leave a crater almost 100 km (60 mi) across. Only three confirmed craters from that time period with that size or greater have been found: Chicxulub , Popigai , and Manicouagan , and all three have been suspected of being linked to extinction events though only Chicxulub,

6804-497: The Earth's crust pose significant challenges to conclusively identifying impacts from this period. Only two pieces of pristine lithosphere are believed to remain from this era: Kaapvaal Craton (in contemporary South Africa) and Pilbara Craton (in contemporary Western Australia) to search within which may potentially reveal evidence in the form of physical craters. Other methods may be used to identify impacts from this period, for example, indirect gravitational or magnetic analysis of

6930-511: The Earth's surface, a theory known as exogenesis . These modified views of Earth's history did not emerge until relatively recently, chiefly due to a lack of direct observations and the difficulty in recognizing the signs of an Earth impact because of erosion and weathering. Large-scale terrestrial impacts of the sort that produced the Barringer Crater , locally known as Meteor Crater , east of Flagstaff, Arizona, are rare. Instead, it

7056-624: The Meteorite Observation and Recovery Project, ran from 1971 to 1985. It too recovered a single meteorite, Innisfree , in 1977. Finally, observations by the European Fireball Network , a descendant of the original Czech program that recovered Příbram, led to the discovery and orbit calculations for the Neuschwanstein meteorite in 2002. NASA has an automated system that detects meteors and calculates

7182-688: The Moon's origin is the giant impact theory, which postulates that Earth was once hit by a planetoid the size of Mars; such a theory is able to explain the size and composition of the Moon, something not done by other theories of lunar formation. According to the theory of the Late Heavy Bombardment , there should have been 22,000 or more impact craters with diameters >20 km (12 mi), about 40 impact basins with diameters about 1,000 km (620 mi), and several impact basins with diameters about 5,000 km (3,100 mi). However, hundreds of millions of years of deformation at

7308-644: The Permian-Triassic extinction is still a matter of debate; the age and origin of proposed impact craters, i.e. the Bedout High structure, hypothesized to be associated with it are still controversial. The last such mass extinction led to the demise of the non-avian dinosaurs and coincided with a large meteorite impact; this is the Cretaceous–Paleogene extinction event (also known as the K–T or K–Pg extinction event), which occurred 66 million years ago. There

7434-721: The Příbram fall, other nations established automated observing programs aimed at studying infalling meteorites. One of these was the Prairie Network , operated by the Smithsonian Astrophysical Observatory from 1963 to 1975 in the midwestern US . This program also observed a meteorite fall, the Lost City chondrite, allowing its recovery and a calculation of its orbit. Another program in Canada,

7560-437: The Solar System was found to be cratered, and there was no reason to believe that the Earth had somehow escaped bombardment from space. In the last few decades of the 20th century, a large number of highly modified impact craters began to be identified. The first direct observation of a major impact event occurred in 1994: the collision of the comet Shoemaker-Levy 9 with Jupiter . Based on crater formation rates determined from

7686-656: The Stan Australia streaming service original television series with the same name . It was the setting for Arthur Upfield 's 1962 novel The Will of the Tribe . The Wolfe Creek crater has considerable claim to be the second most 'obvious' (i.e. relatively undeformed by erosion) meteorite crater known on Earth, after the famous Barringer Crater in Arizona . The crater is mentioned in the 2010 children's science fiction book Alienology that says (in its universe) that

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7812-469: The US as well as several other European countries. Meteorites have figured into human culture since their earliest discovery as ceremonial or religious objects, as the subject of writing about events occurring in the sky and as a source of peril. The oldest known iron artifacts are nine small beads hammered from meteoritic iron. They were found in northern Egypt and have been securely dated to 3200 BC. Although

7938-931: The United States began its own program to search for Antarctic meteorites, operating along the Transantarctic Mountains on the other side of the continent: the Antarctic Search for Meteorites ( ANSMET ) program. European teams, starting with a consortium called "EUROMET" in the 1990/91 season, and continuing with a program by the Italian Programma Nazionale di Ricerche in Antartide have also conducted systematic searches for Antarctic meteorites. The Antarctic Scientific Exploration of China has conducted successful meteorite searches since 2000. A Korean program (KOREAMET)

8064-754: The arid areas of the southwestern United States. To date, thousands of meteorites have been recovered from the Mojave , Sonoran , Great Basin , and Chihuahuan Deserts , with many being recovered on dry lake beds. Significant finds include the three-tonne Old Woman meteorite , currently on display at the Desert Discovery Center in Barstow, California , and the Franconia and Gold Basin meteorite strewn fields; hundreds of kilograms of meteorites have been recovered from each. A number of finds from

8190-406: The atmosphere and fall to Earth as quenched droplets. Extraterrestrial meteorites have been found on the Moon and on Mars. Most meteoroids disintegrate when entering the Earth's atmosphere. Usually, five to ten a year are observed to fall and are subsequently recovered and made known to scientists. Few meteorites are large enough to create large impact craters . Instead, they typically arrive at

8316-516: The atmosphere can appear to be very bright, rivaling the sun in intensity, although most are far dimmer and may not even be noticed during the daytime. Various colors have been reported, including yellow, green, and red. Flashes and bursts of light can occur as the object breaks up. Explosions, detonations, and rumblings are often heard during meteorite falls, which can be caused by sonic booms as well as shock waves resulting from major fragmentation events. These sounds can be heard over wide areas, with

8442-433: The atmosphere, and do not make impact craters. Although such disruption events are uncommon, they can cause a considerable concussion to occur; the famed Tunguska event probably resulted from such an incident. Very large stony objects, hundreds of meters in diameter or more, weighing tens of millions of tons or more, can reach the surface and cause large craters but are very rare. Such events are generally so energetic that

8568-634: The best-known recorded events in modern times was the Tunguska event , which occurred in Siberia , Russia, in 1908. The 2013 Chelyabinsk meteor event is the only known such incident in modern times to result in numerous injuries. Its meteor is the largest recorded object to have encountered the Earth since the Tunguska event. The Comet Shoemaker–Levy 9 impact provided the first direct observation of an extraterrestrial collision of Solar System objects, when

8694-417: The best-known recorded impacts in modern times was the Tunguska event, which occurred in Siberia , Russia, in 1908. This incident involved an explosion that was probably caused by the airburst of an asteroid or comet 5 to 10 km (3.1 to 6.2 mi) above the Earth's surface, felling an estimated 80 million trees over 2,150 km (830 sq mi). In February 1947, another large bolide impacted

8820-652: The biosphere has been the subject of scientific debate. Several theories of impact-related mass extinction have been developed. In the past 500 million years there have been five generally accepted major mass extinctions that on average extinguished half of all species . One of the largest mass extinctions to have affected life on Earth was the Permian-Triassic , which ended the Permian period 250 million years ago and killed off 90 percent of all species; life on Earth took 30 million years to recover. The cause of

8946-780: The case of several meteorite fields, such as Dar al Gani , Dhofar, and others, favorable light-colored geology consisting of basic rocks (clays, dolomites , and limestones ) makes meteorites particularly easy to identify. Although meteorites had been sold commercially and collected by hobbyists for many decades, up to the time of the Saharan finds of the late 1980s and early 1990s, most meteorites were deposited in or purchased by museums and similar institutions where they were exhibited and made available for scientific research . The sudden availability of large numbers of meteorites that could be found with relative ease in places that were readily accessible (especially compared to Antarctica), led to

9072-567: The comet broke apart and collided with Jupiter in July 1994. An extrasolar impact was observed in 2013, when a massive terrestrial planet impact was detected around the star ID8 in the star cluster NGC 2547 by NASA's Spitzer Space Telescope and confirmed by ground observations. Impact events have been a plot and background element in science fiction . In April 2018, the B612 Foundation reported: "It's 100 percent certain we'll be hit [by

9198-399: The course of clearing a field. The result was the discovery of more than 200 new meteorites, mostly stony types. In the late 1960s, Roosevelt County, New Mexico was found to be a particularly good place to find meteorites. After the discovery of a few meteorites in 1967, a public awareness campaign resulted in the finding of nearly 100 new specimens in the next few years, with many being by

9324-404: The crater comes from a nearby creek, which was in turn named after Robert Wolfe (early reports misspell the name as Wolf Creek), a prospector and storekeeper during the gold rush that established the town of Halls Creek. The local Djaru (Jaru) Aboriginal people refer to the crater as Kandimalal . There are multiple Dreaming stories about the formation of the crater. One such story describes

9450-408: The crater's round shape being formed by the passage of a rainbow snake out of the earth, while another snake formed the nearby Sturt Creek. Another story, as told by an Elder, is that one day the crescent moon and the evening star passed very close to each other. The evening star became so hot that it fell to the ground, causing an enormous explosion and flash, followed by a dust cloud. This frightened

9576-583: The deep ocean. The lack of a crater, however, does not mean that an ocean impact would not have dangerous implications for humanity. Some scholars have argued that an impact event in an ocean or sea may create a megatsunami , which can cause destruction both at sea and on land along the coast, but this is disputed. The Eltanin impact into the Pacific Ocean 2.5 Mya is thought to involve an object about 1 to 4 kilometres (0.62 to 2.49 mi) across but remains craterless. The effect of impact events on

9702-533: The discovery of the Winona meteorite in a Native American stone-walled crypt. In medieval China during the Song dynasty , a meteorite strike event was recorded by Shen Kuo in 1064 AD near Changzhou . He reported "a loud noise that sounded like a thunder was heard in the sky; a giant star, almost like the moon, appeared in the southeast" and later finding the crater and the still-hot meteorite within, nearby. Two of

9828-534: The early Solar System and are by far the oldest extant material on Earth. Analysis of terrestrial weathering due to water, salt, oxygen, etc. is used to quantify the degree of alteration that a meteorite has experienced. Several qualitative weathering indices have been applied to Antarctic and desertic samples. The most commonly employed weathering scale, used for ordinary chondrites , ranges from W0 (pristine state) to W6 (heavy alteration). "Fossil" meteorites are sometimes discovered by geologists. They represent

9954-469: The early history of the Earth (about four billion years ago), bolide impacts were almost certainly common since the Solar System contained far more discrete bodies than at present. Such impacts could have included strikes by asteroids hundreds of kilometers in diameter, with explosions so powerful that they vaporized all the Earth's oceans. It was not until this heavy bombardment slackened that life appears to have begun to evolve on Earth. The leading theory of

10080-450: The extremely arid climate, there has been relatively little weathering or sedimentation on the surface for tens of thousands of years, allowing meteorites to accumulate without being buried or destroyed. The dark-colored meteorites can then be recognized among the very different looking limestone pebbles and rocks. In 1986–87, a German team installing a network of seismic stations while prospecting for oil discovered about 65 meteorites on

10206-424: The fireball or the impact of the object on the ground, or both. Therefore, despite the fact that meteorites fall with virtually equal probability everywhere on Earth, verified meteorite falls tend to be concentrated in areas with higher human population densities such as Europe, Japan, and northern India. A small number of meteorite falls have been observed with automated cameras and recovered following calculation of

10332-526: The fireball. The images were used both to determine the location of the stones on the ground and, more significantly, to calculate for the first time an accurate orbit for a recovered meteorite. Following the Příbram fall, other nations established automated observing programs aimed at studying infalling meteorites. One of these was the Prairie Meteorite Network , operated by the Smithsonian Astrophysical Observatory from 1963 to 1975 in

10458-457: The first time, including ribose , suggesting that chemical processes on asteroids can produce some organic compounds fundamental to life, and supporting the notion of an RNA world prior to a DNA-based origin of life on Earth. In 2022, a Japanese group reported that they had found adenine (A), thymine (T), guanine (G), cytosine (C) and uracil (U) inside carbon-rich meteorites. These compounds are building blocks of DNA and RNA ,

10584-625: The globe. Two 10-kilometre sized asteroids are now believed to have struck Australia between 360 and 300 million years ago at the Western Warburton and East Warburton Basins , creating a 400-kilometre impact zone. According to evidence found in 2015, it is the largest ever recorded. A third, possible impact was also identified in 2015 to the north, on the upper Diamantina River , also believed to have been caused by an asteroid 10 km across about 300 million years ago, but further studies are needed to establish that this crustal anomaly

10710-449: The ground to become meteorites. An estimated 500 meteorites reach the surface each year, but only 5 or 6 of these typically create a weather radar signature with a strewn field large enough to be recovered and be made known to scientists. The late Eugene Shoemaker of the U.S. Geological Survey estimated the rate of Earth impacts, concluding that an event about the size of the nuclear weapon that destroyed Hiroshima occurs about once

10836-552: The highly weathered remains of meteorites that fell to Earth in the remote past and were preserved in sedimentary deposits sufficiently well that they can be recognized through mineralogical and geochemical studies. The Thorsberg limestone quarry in Sweden has produced an anomalously large number – exceeding one hundred – fossil meteorites from the Ordovician , nearly all of which are highly weathered L-chondrites that still resemble

10962-495: The history of the Earth, a significant geological and climatic influence. The Moon 's existence is widely attributed to a huge impact early in Earth's history . Impact events earlier in the history of Earth have been credited with creative as well as destructive events; it has been proposed that impacting comets delivered the Earth's water, and some have suggested that the origins of life may have been influenced by impacting objects by bringing organic chemicals or lifeforms to

11088-456: The hot deserts of Australia . Several dozen meteorites had already been found in the Nullarbor region of Western and South Australia . Systematic searches between about 1971 and the present recovered more than 500 others, ~300 of which are currently well characterized. The meteorites can be found in this region because the land presents a flat, featureless, plain covered by limestone . In

11214-586: The impact point. The first of these was the Příbram meteorite , which fell in Czechoslovakia (now the Czech Republic) in 1959. In this case, two cameras used to photograph meteors captured images of the fireball. The images were used both to determine the location of the stones on the ground and, more significantly, to calculate for the first time an accurate orbit for a recovered meteorite. Following

11340-507: The impactor is completely destroyed, leaving no meteorites. (The first example of a stony meteorite found in association with a large impact crater, the Morokweng impact structure in South Africa, was reported in May 2006.) Several phenomena are well documented during witnessed meteorite falls too small to produce hypervelocity craters. The fireball that occurs as the meteoroid passes through

11466-599: The kinetic energy released in an impact event. The more energy is released, the more damage is likely to occur on the ground due to the environmental effects triggered by the impact. Such effects can be shock waves, heat radiation, the formation of craters with associated earthquakes, and tsunamis if bodies of water are hit. Human populations are vulnerable to these effects if they live within the affected zone. Large seiche waves arising from earthquakes and large-scale deposit of debris can also occur within minutes of impact, thousands of kilometres from impact. Stony asteroids with

11592-549: The laboratory under outer space conditions, using starting chemicals, such as pyrimidine , found in meteorites. Pyrimidine and polycyclic aromatic hydrocarbons (PAHs) may have been formed in red giants or in interstellar dust and gas clouds, according to the scientists. In 2018, researchers found that 4.5 billion-year-old meteorites found on Earth contained liquid water along with prebiotic complex organic substances that may be ingredients for life. In 2019, scientists reported detecting sugar molecules in meteorites for

11718-465: The largest known still existing craters/impact structures on Earth, with the impactors having estimated diameters of ~20–50 kilometres (12–31 mi), with the craters generated by these impacts having an estimated diameter of 400–1,000 kilometres (250–620 mi). The largest impacts like those represented by the S2 layer are likely to have had far-reaching effects, such as the boiling of the surface layer of

11844-404: The largest of the three, has been consistently considered. The impact that caused Mistastin crater generated temperatures exceeding 2,370 °C, the highest known to have occurred on the surface of the Earth. Besides the direct effect of asteroid impacts on a planet's surface topography, global climate and life, recent studies have shown that several consecutive impacts might have an effect on

11970-479: The largest verified crater, a multi-ringed structure 160–300 km (100–200 mi) across, forming from an impactor approximately 10–15 km (6.2–9.3 mi) in diameter. The Sudbury impact event occurred on the Nuna supercontinent (now Canada ) from a bolide approximately 10–15 km (6.2–9.3 mi) in diameter approximately 1.849 billion years ago Debris from the event would have been scattered across

12096-427: The mantle, but may prove inconclusive. In 2021, evidence for a probable impact 3.46 billion-years ago at Pilbara Craton has been found in the form of a 150 kilometres (93 mi) crater created by the impact of a 10 kilometres (6.2 mi) asteroid (named "The Apex Asteroid") into the sea at a depth of 2.5 kilometres (1.6 mi) (near the site of Marble Bar, Western Australia ). The event caused global tsunamis. It

12222-533: The mass at around 100,000 kg (220,000 lb). It was an iron meteorite belonging to the chemical group IIAB and with a coarse octahedrite structure. More than 70 tonnes ( metric tons ) of material survived the collision. A case of a human injured by a space rock occurred on November 30, 1954, in Sylacauga, Alabama . There a 4 kg (8.8 lb) stone chondrite crashed through a roof and hit Ann Hodges in her living room after it bounced off her radio. She

12348-463: The meteoroid maintains a fixed orientation for some time, without tumbling, it may develop a conical "nose cone" or "heat shield" shape. As it decelerates, eventually the molten surface layer solidifies into a thin fusion crust, which on most meteorites is black (on some achondrites , the fusion crust may be very light-colored). On stony meteorites, the heat-affected zone is at most a few mm deep; in iron meteorites, which are more thermally conductive,

12474-513: The midwestern U.S. This program also observed a meteorite fall, the "Lost City" chondrite, allowing its recovery and a calculation of its orbit. Another program in Canada, the Meteorite Observation and Recovery Project, ran from 1971 to 1985. It too recovered a single meteorite, "Innisfree", in 1977. Finally, observations by the European Fireball Network, a descendant of the original Czech program that recovered Příbram, led to

12600-437: The more notable meteorites recovered include Tissint and Northwest Africa 7034 . Tissint was the first witnessed Martian meteorite fall in more than fifty years; NWA 7034 is the oldest meteorite known to come from Mars, and is a unique water-bearing regolith breccia. In 1999, meteorite hunters discovered that the desert in southern and central Oman were also favorable for the collection of many specimens. The gravel plains in

12726-584: The most convincing evidence for a worldwide catastrophe was the discovery of the crater which has since been named Chicxulub Crater . This crater is centered on the Yucatán Peninsula of Mexico and was discovered by Tony Camargo and Glen Penfield while working as geophysicists for the Mexican oil company PEMEX . What they reported as a circular feature later turned out to be a crater estimated to be 180 km (110 mi) in diameter. This convinced

12852-521: The number of deaths implausible. Kamil Crater , discovered from Google Earth image review in Egypt , 45 m (148 ft) in diameter and 10 m (33 ft) deep, is thought to have been formed less than 3,500 years ago in a then-unpopulated region of western Egypt. It was found February 19, 2009 by V. de Michelle on a Google Earth image of the East Uweinat Desert, Egypt. One of

12978-675: The oceans. The Maniitsoq structure , dated to around 3 billion years old (3 Ga), was once thought to be the result of an impact; however, follow-up studies have not confirmed its nature as an impact structure. The Maniitsoq structure is not recognised as an impact structure by the Earth Impact Database . In 2020, scientists discovered the world's oldest confirmed impact crater, the Yarrabubba crater , caused by an impact that occurred in Yilgarn Craton (what

13104-808: The oldest recorded meteorite falls in Europe are the Elbogen (1400) and Ensisheim (1492) meteorites. The German physicist, Ernst Florens Chladni , was the first to publish (in 1794) the idea that meteorites might be rocks that originated not from Earth, but from space. His booklet was "On the Origin of the Iron Masses Found by Pallas and Others Similar to it, and on Some Associated Natural Phenomena" . In this he compiled all available data on several meteorite finds and falls concluded that they must have their origins in outer space. The scientific community of

13230-406: The only materials from other planets ever recovered by humans. About 5% of meteorites that have been seen to fall are iron meteorites composed of iron- nickel alloys , such as kamacite and/or taenite . Most iron meteorites are thought to come from the cores of planetesimals that were once molten. As with the Earth, the denser metal separated from silicate material and sank toward the center of

13356-502: The orbit, magnitude, ground track , and other parameters over the southeast USA, which often detects a number of events each night. Until the twentieth century, only a few hundred meteorite finds had ever been discovered. More than 80% of these were iron and stony-iron meteorites, which are easily distinguished from local rocks. To this day, few stony meteorites are reported each year that can be considered to be "accidental" finds. The reason there are now more than 30,000 meteorite finds in

13482-595: The original meteorite under a petrographic microscope , but which have had their original material almost entirely replaced by terrestrial secondary mineralization. The extraterrestrial provenance was demonstrated in part through isotopic analysis of relict spinel grains, a mineral that is common in meteorites, is insoluble in water, and is able to persist chemically unchanged in the terrestrial weathering environment. Scientists believe that these meteorites, which have all also been found in Russia and China, all originated from

13608-487: The parent body of the Vesta Family , although this claim is disputed. Others derive from unidentified asteroids. Two small groups of achondrites are special, as they are younger and do not appear to come from the asteroid belt. One of these groups comes from the Moon, and includes rocks similar to those brought back to Earth by Apollo and Luna programs. The other group is almost certainly from Mars and constitutes

13734-442: The people and a long time passed before they ventured near the crater to see what had happened. When they finally went there, they realised that this was the site where the evening star had fallen to the Earth. The Djaru people named the place "Kandimalal" and it is prominent in art from the region. The crater was featured in the 2005 Australian horror film Wolf Creek , and the sequel in 2013, Wolf Creek 2 . It also features in

13860-569: The planetesimal, forming its core. After the planetesimal solidified, it broke up in a collision with another planetesimal. Due to the low abundance of iron meteorites in collection areas such as Antarctica, where most of the meteoric material that has fallen can be recovered, it is possible that the percentage of iron-meteorite falls is lower than 5%. This would be explained by a recovery bias; laypeople are more likely to notice and recover solid masses of metal than most other meteorite types. The abundance of iron meteorites relative to total Antarctic finds

13986-455: The result of impact events on solid objects and, as the dominant landforms on many of the System's solid objects, present the most solid evidence of prehistoric events. Notable impact events include the hypothesized Late Heavy Bombardment , which would have occurred early in the history of the Earth–Moon system, and the confirmed Chicxulub impact 66 million years ago, believed to be the cause of

14112-495: The size of the Chicxulub crater, which did not result in any mass extinctions, and there is no clear linkage between an impact and any other incident of mass extinction. Paleontologists David M. Raup and Jack Sepkoski have proposed that an excess of extinction events occurs roughly every 26 million years (though many are relatively minor). This led physicist Richard A. Muller to suggest that these extinctions could be due to

14238-535: The so-called "Northwest Africa" meteorites. When they get classified, they are named "Northwest Africa" (abbreviated NWA) followed by a number. It is generally accepted that NWA meteorites originate in Morocco, Algeria, Western Sahara, Mali, and possibly even further afield. Nearly all of these meteorites leave Africa through Morocco. Scores of important meteorites, including Lunar and Martian ones, have been discovered and made available to science via this route. A few of

14364-455: The structure of the metal may be affected by heat up to 1 centimetre (0.39 in) below the surface. Reports vary; some meteorites are reported to be "burning hot to the touch" upon landing, while others are alleged to have been cold enough to condense water and form a frost. Meteoroids that disintegrate in the atmosphere may fall as meteorite showers, which can range from only a few up to thousands of separate individuals. The area over which

14490-495: The surface at their terminal velocity and, at most, create a small pit. Large meteoroids may strike the earth with a significant fraction of their escape velocity (second cosmic velocity), leaving behind a hypervelocity impact crater. The kind of crater will depend on the size, composition, degree of fragmentation, and incoming angle of the impactor. The force of such collisions has the potential to cause widespread destruction. The most frequent hypervelocity cratering events on

14616-647: The time responded with resistance and mockery. It took nearly ten years before a general acceptance of the origin of meteorites was achieved through the work of the French scientist Jean-Baptiste Biot and the British chemist, Edward Howard . Biot's study, initiated by the French Academy of Sciences , was compelled by a fall of thousands of meteorites on 26 April 1803 from the skies of L'Aigle, France. Impact event Impact events appear to have played

14742-645: The total number of well-described meteorites found in Algeria and Libya to more than 500. Meteorite markets came into existence in the late 1990s, especially in Morocco . This trade was driven by Western commercialization and an increasing number of collectors. The meteorites were supplied by nomads and local people who combed the deserts looking for specimens to sell. Many thousands of meteorites have been distributed in this way, most of which lack any information about how, when, or where they were discovered. These are

14868-607: The use of the metal found in meteorites is also recorded in myths of many countries and cultures where the celestial source was often acknowledged, scientific documentation only began in the last few centuries. Meteorite falls may have been the source of cultish worship . The cult in the Temple of Artemis at Ephesus, one of the Seven Wonders of the Ancient World , possibly originated with the observation and recovery of

14994-541: The vast majority of scientists that this extinction resulted from a point event that is most probably an extraterrestrial impact and not from increased volcanism and climate change (which would spread its main effect over a much longer time period). Although there is now general agreement that there was a huge impact at the end of the Cretaceous that led to the iridium enrichment of the K-T boundary layer, remnants have been found of other, smaller impacts, some nearing half

15120-588: The world's collections started with the discovery by Harvey H. Nininger that meteorites are much more common on the surface of the Earth than was previously thought. Nininger's strategy was to search for meteorites in the Great Plains of the United States, where the land was largely cultivated and the soil contained few rocks. Between the late 1920s and the 1950s, he traveled across the region, educating local people about what meteorites looked like and what to do if they thought they had found one, for example, in

15246-464: Was badly bruised by the fragments . Several persons have since claimed to have been struck by "meteorites" but no verifiable meteorites have resulted. A small number of meteorite falls have been observed with automated cameras and recovered following calculation of the impact point. The first was the Příbram meteorite , which fell in Czechoslovakia (now the Czech Republic) in 1959. In this case, two cameras used to photograph meteors captured images of

15372-427: Was considered to be highly successful. The orbital period of the target body was changed by 32 minutes. The criterion for success was a change of more than 73 seconds. Major impact events have significantly shaped Earth's history , having been implicated in the formation of the Earth–Moon system , the evolutionary history of life , the origin of water on Earth , and several mass extinctions . Impact structures are

15498-422: Was correctly identified as an impact crater, and it was not until as recently as 1963 that research by Eugene Merle Shoemaker conclusively proved this hypothesis. The findings of late 20th-century space exploration and the work of scientists such as Shoemaker demonstrated that impact cratering was by far the most widespread geological process at work on the Solar System's solid bodies. Every surveyed solid body in

15624-482: Was indeed the result of an impact event. The prehistoric Chicxulub impact , 66 million years ago, believed to be the cause of the Cretaceous–Paleogene extinction event, was caused by an asteroid estimated to be about 10 kilometres (6.2 mi) wide. Analysis of the Hiawatha Glacier reveals the presence of a 31 km wide impact crater dated at 58 million years of age, less than 10 million years after

15750-466: Was launched in 2007 and has collected a few meteorites. The combined efforts of all of these expeditions have produced more than 23,000 classified meteorite specimens since 1974, with thousands more that have not yet been classified. For more information see the article by Harvey (2003). At about the same time as meteorite concentrations were being discovered in the cold desert of Antarctica, collectors discovered that many meteorites could also be found in

15876-477: Was widely thought that cratering was the result of volcanism : the Barringer Crater, for example, was ascribed to a prehistoric volcanic explosion (not an unreasonable hypothesis, given that the volcanic San Francisco Peaks stand only 48 km or 30 mi to the west). Similarly, the craters on the surface of the Moon were ascribed to volcanism. It was not until 1903–1905 that the Barringer Crater

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