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Artist's impression of a major impact event. The collision between Earth and an asteroid a few kilometers in diameter may release as much energy as several million nuclear weapons detonating.
Artist's impression of a major impact event. The collision between Earth and an asteroid a few kilometers in diameter may release as much energy as several million nuclear weapons detonating.
See also: Impact crater

Impact events are caused by the collision of large meteoroids, asteroids or comets (generically: bolides) with Earth and may sometimes be followed by mass extinctions of life. In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body A collision is an isolated event in which two or more bodies (colliding bodies exert relatively strong forces on each other for a relatively short time Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 An extinction event (also known as mass extinction; extinction-level event, ELE is a sharp decrease in the number of Species in a relatively short period

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The geology of Earth-impact events

The Earth has gone through periods of abrupt and catastrophic change, some due to the impact of large asteroids and comets on the planet. A few of these impacts may have caused massive climate change and the extinction of large numbers of plant and animal species. In Biology and Ecology, extinction is the cessation of existence of a Species or group of taxa. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. The Moon is widely attributed to be the result of a huge impact early in Earth's history. Impact events even earlier in the history of Earth have been credited with creative as well as destructive events; it has been proposed that the water in the Earth's oceans was delivered by impacting comets, and some have suggested that the origins of life may have been influenced by impacting objects bringing organic chemicals or lifeforms to the Earth's surface, a theory known as exogenesis. The history of Earth covers approximately 46 billion years (4567000000 years from Earth ’s formation out of the Solar nebula to the present An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. In the Natural sciences, Abiogenesis, or origin of life, is the study of how Life on Earth emerged from Inanimate Organic

Eugene Merle Shoemaker was first to prove that meteor impacts have affected the Earth.
Eugene Merle Shoemaker was first to prove that meteor impacts have affected the Earth. Eugene Merle Shoemaker (or Gene Shoemaker ( April 28, 1928  &ndash July 18, 1997) was one of the founders of the fields of Planetary EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

These modified views of the Earth's history did not emerge until relatively recently, chiefly due to a lack of direct observations and the difficulty in recognising the signs of an Earth impact. Large-scale terrestrial impacts of the sort that produced the Barringer Crater in Arizona are rare. Meteor Crater is a Meteorite Impact crater located approximately 43 miles east of Flagstaff, near Winslow in the northern The State of Arizona ( is a state located in the southwestern region of the United States. Instead, it 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 30 miles (48 km) to the west. Plate tectonics and hotspots Divergent plate boundaries At the The San Francisco Peaks are a Volcanic Mountain range located in north central Arizona, United States, just north of Flagstaff Similarly, the craters on the surface of the Moon were ascribed to volcanism.

It was not until 1903–1905 that the Barringer Crater was correctly identified as being an impact crater, and it was not until as recently as 1963 that research by Eugene Merle Shoemaker conclusively proved this hypothesis. Eugene Merle Shoemaker (or Gene Shoemaker ( April 28, 1928  &ndash July 18, 1997) was one of the founders of the fields of Planetary 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. History First orbital flights The first successful orbital launch was of the Soviet unmanned Sputnik As literally every surveyed solid body in the Solar System was found to be cratered, there was no reason to believe that the Earth had somehow escaped bombardment from space. In 1994, the first major impact event was directly observed: the collision of the comet Shoemaker-Levy 9 with Jupiter; to date, no such events have been observed on Earth. Shoemaker-Levy redirects here For other Shoemaker-Levy comets see List of periodic comets.

Based on crater formation rates determined from 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 five kilometers or more. In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body Planetary geology, alternatively known as astrogeology or exogeology, is a Planetary science discipline concerned with the Geology of the EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The smallest of these impactors would release the equivalent of ten million megatons of TNT and leave a crater 95 kilometers across. Trinitrotoluene ( TNT) is a Chemical compound with the formula C6H2(NO23CH3 For comparison, the largest nuclear weapon ever detonated, the Tsar Bomba, had a yield of 50 megatons. A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. Tsar Bomba (ru Царь-бомба literally " King Bomb" is the Western name for the RDS-220 hydrogen bomb (codenamed "Иван" (Ivan by its

Mass extinctions and impacts

In the past 600 million years there have been five major mass extinctions that on average extinguished half of all species. An extinction event (also known as mass extinction; extinction-level event, ELE is a sharp decrease in the number of Species in a relatively short period In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. The largest mass extinction to have affected life on Earth was in the Permian-Triassic, which ended the Permian period 250 million years ago and killed off 90% of all species. The Permian–Triassic (P–Tr extinction event, informally known as the Great Dying, was an Extinction event that occurred, and 70 percent of terrestrial The Permian is a geologic period and system that extends from 299 [1] The last such mass extinction led to the demise of the dinosaurs and coincided with a large asteroid impact; this is the Cretaceous–Tertiary extinction event. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but The Cretaceous–Tertiary extinction event, which occurred approximately ( Ma) was a large-scale mass extinction of animal and plant species in a geologically There is no definitive evidence of impacts leading to the four other major mass extinctions, though a recent report from Ohio State scientists stated that they have located a 483 km diameter impact crater beneath the East Antarctic Ice Sheet which may date back about 250 million years, based on gravity measurements, which might associate it with the Permian-Triassic extinction event. An extinction event (also known as mass extinction; extinction-level event, ELE is a sharp decrease in the number of Species in a relatively short period

In 1980, physicist Luis Alvarez, his son, geologist Walter Alvarez, and nuclear chemists Frank Asaro and Helen V. Luis W Alvarez (June 13 1911 San Francisco California &ndash September 1 1988 was an American physicist and Inventor, who spent nearly For his grandfather the American doctor see Walter C Alvarez. 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. The University of California Berkeley (also referred to as Cal, Berkeley and UC Berkeley) is a major research university located in Berkeley Iridium (ɪˈrɪdiəm is a Chemical element that has the symbol Ir and Atomic number 77 In Geology and related fields a stratum (plural strata) is a layer of rock or Soil with internally consistent characteristics that distinguishes Iridium is an element that is rare on Earth but relatively abundant in many meteorites. A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface 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 10–14 kilometers must have collided with the earth. This iridium layer at the K–T boundary has been found worldwide at 100 different sites. The K-T boundary is a geological signature usually a thin band dated to 65 Multidirectionally shocked quartz (coesite), which is only known to form as the result of large impacts or atomic bomb explosions, has also been found in the same layer at more than 30 sites. Shocked quartz is a form of Quartz that has a microscopic structure that is different from normal quartz A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. Soot and ash at levels tens of thousands times normal levels were found with the above. Soot (ˈsʊt is a general term that refers to the black impure carbon particles resulting from the incomplete combustion of a hydrocarbon

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, therefore these isotopic anomalies exclude a volcanic origin which was also proposed as a cause for the iridium enrichment. Furthermore the chromium isotopic ratios measured in the K-T boundary are similar to the chromium isotopic ratios found in carbonaceous chondrites. A carbonaceous chondrite or a C-type chondrite is a type of chondritic Meteorite which contains high levels of Water and Organic compounds Thus a probable candidate for the impactor is a carbonaceous asteroid but also a comet is possible because comets are assumed to consist of material similar to carbonaceous chondrites.

Probably the most convincing evidence for a worldwide catastrophe was the discovery of the crater which has since been named Chicxulub Crater. The Chicxulub Crater (tʃikʃuˈlub is an ancient Impact crater buried underneath the Yucatán Peninsula in Mexico. This crater is centered on the Yucatán Peninsula of Mexico and was discovered by Tony Camargo and Glen Pentfield while working as geophysicists for the Mexican oil company PEMEX. The Yucatán Peninsula, in Southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico. The United Mexican States ( or commonly Mexico (ˈmɛksɪkoʊ () is a federal constitutional Republic in North America. Geophysics, a major discipline of Earth sciences, is the study of the Earth by quantitative physical methods especially by seismic, electromagnetic Petroleum ( L petroleum, from Greek πετρέλαιον, lit Petróleos Mexicanos ( PEMEX) is Mexico 's state-owned Petroleum company What they reported as a circular feature later turned out to be a crater estimated to be 180 kilometers in diameter. Other researchers would later find that the end-Cretaceous extinction event that wiped out the dinosaurs had lasted for thousands of years instead of millions of years as had previously been thought. This convinced 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).

Recently, several craters around the world have been dated to approximately the same age as Chicxulub — for example, the Silverpit crater in the United Kingdom and the Boltysh crater in Ukraine. Silverpit crater is a buried sub-sea structure under the North Sea off the coast of the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located The Boltysh Crater is an impact crater in the Kirovohrad Oblast province of Ukraine. Ukraine (Україна Ukrayina, /ukrɑˈjinɑ/ is a country in Eastern Europe. This has led to the suggestion that the Chicxulub impact was one of several that occurred almost simultaneously, perhaps due to a disrupted comet impacting the Earth in a similar manner to the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994. A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — Shoemaker-Levy redirects here For other Shoemaker-Levy comets see List of periodic comets.

It was the lack of high concentrations of iridium and shocked quartz which has prevented the acceptance of the idea that the Permian extinction (so-called mother of mass extinctions) was also caused by an impact. However, during the late Permian all the continents were combined into one supercontinent named Pangaea and all the oceans formed one superocean, Panthalassa. A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in Panthalassa ( Greek, meaning 'all seas' also known as the Panthalassic Ocean, was the vast global Ocean that surrounded the Supercontinent If an impact occurred in the ocean and not on land at all, then there would be little shocked quartz released (since oceanic crust has relatively little silica) and much less material. The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide None of this takes into account the East Antarctic Ice Sheet crater, which is a recent find.

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 impacts of the same order of magnitude that did not result in any mass extinctions, and there is no clear linkage between an impact and any other incident of mass extinction.

Nonetheless it is now widely believed that mass extinctions due to impacts are an occasional event in the history of Earth. The history of Earth covers approximately 46 billion years (4567000000 years from Earth ’s formation out of the Solar nebula to the present One such controversial hypothesis is Tollmann's hypothetical bolide, which claims that the Holocene was initiated by an impact. Alexander Tollmann's bolide, proposed by Kristen-Tollmann and Tollmann (1994 is a hypothesis presented by Austrian Geologist Dr The Holocene is a Geological epoch which began approximately 10000 years ago (about 8000 BC

Paleontologists David M. Raup and Jack Sepkoski have proposed that an extinction occurs roughly every 26 million years (though many are relatively minor). David M Raup is a University of Chicago Paleontologist. Raup studied the Fossil record and the diversity of life on Earth. J John Sepkoski Jr. ( July 26, 1948 - May 1, 1999) was a University of Chicago Paleontologist. This led physicist Richard A. Muller to suggest that these extinctions could be due to a hypothetical companion star to the sun called Nemesis periodically disrupting the orbits of comets in the Oort cloud, and leading to a large increase in the number of comets reaching the inner solar system where they might hit Earth. Richard A Muller of San Francisco California, US, is a Physicist who works at the University of California Berkeley and Lawrence Berkeley Nemesis is a hypothetical Red dwarf star or Brown dwarf, orbiting the Sun at a distance of about 50000 to 100000 AU, somewhat The Oort cloud ( ort alternatively the Öpik-Oort Cloud) is a hypothetical spherical cloud of Comets believed to lie roughly 50 000 AU,

Indeed, in 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. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 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. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. It was not until this heavy bombardment began to slacken that life appears to have begun to evolve on Earth. Life is a state that distinguishes Organisms from non-living objects such as non-life and dead organisms being manifested by growth through Metabolism EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

The leading theory of the Moon's origin is the giant impact theory, which states that Earth was once hit by a planetoid the size of Mars; if this theory holds then that impact was almost certainly the largest hit Earth ever suffered. Minor planet is a term used since the 19th century to describe objects such as Asteroids that are in Orbit around the Sun but are not Planets

Recent pre-historic impact events

In addition to the extremely large impacts that happen every few tens of millions of years, there are many smaller impacts that occur much more frequently but which leave correspondingly smaller traces behind. Due to the strong forces of erosion at work on Earth, only relatively recent examples of these smaller impacts are known. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind A few of the more famous or interesting examples are:

More recent prehistoric impacts are theorized by the Holocene Impact Working Group, including Dallas Abbott of Lamont-Doherty Earth Observatory in Palisades, N. The Wabar craters are Meteorite Impact craters found by accident by an explorer searching for the legendary city of Ubar in Arabia Y. [2] This group points to four enormous chevron sediment deposits at the southern end of Madagascar, containing deep-ocean microfossils fused with metals typically formed by cosmic impacts. The Fenambosy Chevron is one of four chevron-shaped land features on the southwest coast of Madagascar, near the tip of Madagascar 600 feet (180 m high and three All of the chevrons point toward a spot in the middle of the Indian Ocean where newly discovered Burckle crater[3], 18 miles (29 km) in diameter, lies 12,500 feet (3,800 m) below the surface. Burckle Crater is an undersea crater likely to have been formed by a very large scale Comet or Meteorite impact event. This group posits that a large asteroid or comet impact 4,500--5,000 years ago, produced a mega-tsunami at least 600 feet (180 m) high. If this and other recent impacts prove correct, the rate of asteroid impacts is much higher than currently thought.

Holocene impact events have been proposed by the dendrochronologist Mike Baillie as a possible cause of several brief (typically 5-10 year) climatic downturns recorded in ancient tree ring patterns. The Holocene is a Geological epoch which began approximately 10000 years ago (about 8000 BC Dendrochronology (from Greek grc δένδρον dendron, "tree" grc χρόνος khronos, "time" and grc -λογία In his book 'Exodus to Arthur: Catastrophic encounters with comets,' he highlights four such events and suggests that these might have been caused by the dust veils thrown up by the impact of cometary debris.

Modern impact events

In China’s Shanxi Province, 10,000 people were said to have been killed in 1490 by a hail of "falling stones" that some astronomers surmise may have been triggered by the breakup of a large asteroid. ( Postal map spelling: Shansi) is a province in the northern part of the People's Republic of China. [4]

The most significant recorded impact in recent times was the Tunguska event, which occurred in Siberia, Russia, in 1908. The Tunguska Event, or Tunguska explosion, was a powerful Explosion that occurred near the Podkamennaya (Lower Stony Tunguska River in what is now Siberia (Сиби́рь Sibir) is the name given to the vast region constituting almost all of Northern Asia and for the most part currently serving Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending This incident involved an explosion that was probably caused by the airburst of an asteroid or comet 5 to 10 kilometers (3–6 mi) above the Earth's surface, felling an estimated 80 million trees over 2,150 square kilometers (830 sq mi). Although the Tunguska event was both spectacular and unparalleled in any historical record, it no longer seems as unique and unusual as it once did.

The late Eugene Shoemaker of the U.S. Geological Survey came up with an estimate of the rate of Earth impacts, and suggested that an event about the size of the nuclear weapon that destroyed Hiroshima occurs about once a year. The United States Geological Survey ( USGS) is a scientific agency of the United States government. The Japanese city of ( is the capital of Hiroshima Prefecture, and the largest city in the Chūgoku region of western Honshū, the largest of Japan 's 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.

Some have been observed. Noteworthy examples include the Sikhote-Alin Meteorite fall in Primorye, far eastern Russia, in 1947, and the Revelstoke fireball of 1965, which occurred over the snows of British Columbia, Canada. Sikhote-Alin is an iron Meteorite fell in 1947 on the Sikhote-Alin Mountains in ( Russia) Primorye may refer to Primorye, informal name of Primorsky Krai, Russia Primorye (urban-type settlement, an urban-type settlement Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending Revelstoke ('rɛvəlstoʊk (population 7500 municipal est 2005 is a city in southeastern British Columbia, Canada. British Columbia (ˌbrɪtɨʃ kəˈlʌmbiə ( BC) ( (la Colombie-Britannique C Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page Another fireball blew up over the Australian town of Dubbo in April 1993, shaking things up but causing no harm. For a topic outline on this subject see List of basic Australia topics. Dubbo is a city in the Central West Region of New South Wales, Australia.

A small number of meteorite falls have been observed with automated cameras and recovered following calculation of the impact point. A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface The first of these was the Pribram meteorite, which fell in Czechoslovakia (now the Czech Republic) in 1959. Příbram (ˈpr̝̊iːbram Pibrans earlier Freiberg in Böhmen) is a city in the Central Bohemian Region of the Czech Republic with a population of 35147 Czechoslovakia may also refer to what is now the Czech Republic and Slovakia. The Czech Republic ( ˈt͡ʃɛskaː ˈrɛpuˌblɪka short form in Česko ˈt͡ʃɛskɔ also called Czechia, [5] 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 the Pribram 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. The Smithsonian Astrophysical Observatory (SAO is a "research institute" of the Smithsonian Institution headquartered in Cambridge Massachusetts, This program also observed a meteorite fall, the Lost City chondrite, allowing its recovery and a calculation of its orbit. [6] Another program in Canada, the Meteorite Observation and Recovery Project, ran from 1971 to 1985. It too recovered a single meteorite, Innisfree, in 1977. [7] Finally, observations by the European Fireball Network, a descendant of the original Czech program that recovered Pribram, led to the discovery and orbit calculations for the Neuschwanstein meteorite in 2002. Neuschwanstein Castle ( German: Schloss Neuschwanstein, lit New Swan Stone palace; nɔʏˈʃvaːnʃtaɪ̯n is a 19th-century Bavarian [8]

The only reported fatality from meteorite impacts is an Egyptian dog who was killed in 1911 by the Nakhla meteorite, although this report is disputed. The Nakhla meteorite, the first example of a Nakhlite type meteorite of the SNC Group type of meteorites fell to Earth from Mars on the 28th of The meteorites that struck this area were identified in the 1980s as Martian in origin.

The first known modern case of a human hit by a space rock [1] occurred on November 30, 1954 in Sylacauga, Alabama. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus Events 1700 - Battle of Narva — A Swedish army of 8500 men under Charles XII defeats Year 1954 ( MCMLIV) was a Common year starting on Friday (link will display full 1954 Gregorian calendar) Sylacauga is a city in Talladega County, Alabama, United States. There a 4 kg stone chondrite [2] crashed through a roof and hit Ann Hodges in her living room after it bounced off her radio. The Hodges Meteorite is the only documented extraterrestrial object to have struck a Human being. Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. She was badly bruised. Several persons have since claimed [3] to have been struck by 'meteorites' but no verifiable meteorites have resulted.

A particularly interesting fireball was observed moving north over the Rocky Mountains from the U. Mountain peaks of the Rocky Mountains The Rocky Mountains, often called the Rockies, are a Mountain range in western North America. S. Southwest to Canada on August 10, 1972, and was filmed by a tourist at the Grand Teton National Park in Wyoming with an 8-millimeter color movie camera [9] The object was in the range of size from a car to a house and should have ended its life in a Hiroshima-sized blast, but there was never any explosion, much less a crater. Events 612 BC - Killing of Sinsharishkun, King of Assyrian Empire Year 1972 ( MCMLXXII) was a Leap year starting on Saturday (link will display full calendar of the Gregorian calendar. Grand Teton National Park is a United States National Park located in northwestern Wyoming, south of Yellowstone National Park. The State of Wyoming ( is a sparsely populated state in the western region of the United States. Analysis of the trajectory indicated that it never came much lower than 58 kilometers off the ground, and the conclusion was that it had grazed Earth's atmosphere for about 100 seconds, then skipped back out of the atmosphere to return to its orbit around the Sun.

On the dark morning hours of January 18, 2000, a fireball exploded over the town of Whitehorse in the Canadian Yukon at an altitude of about 26 kilometers, lighting up the night like day. Events 350 - Generallus Magnentius deposes Roman Emperor Constans and proclaims himself Emperor 2000 ( MM) was a Leap year that started on Saturday of the Common Era, in accordance with the Gregorian calendar. Whitehorse (ˈʍaɪthɔrs ( 2006 population 20461 CA population 22898 (formerly White Horse until 1957 - 03-21) is the Yukon (ˈjuːkɒn is the westernmost and smallest of Canada's three territories. The meteor that produced the fireball was estimated to be about 4. 6 meters in diameter and with a weight of 180 tonnes. This blast was also featured on the The Science Channel series Killer Asteroids, with several witness reports from residents in Atlin, British Columbia. Science Channel is a cable and satellite television network produced by Discovery Communications. Atlin is a community in northwestern British Columbia, Canada, located on Atlin Lake.

A meteor was observed striking Reisadalen in Nordreisa municipality in Troms County, Norway, on June 7, 2006. Nordreisa is a municipality in the county of Troms Norway. Nordreisa was separated from Skjervøy January 1 1886 or Romsa ( Sami language) is a county in North Norway, bordering Finnmark to the northeast and Nordland in the southwest Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional Events 1099 - The First Crusade: The Siege of Jerusalem begins Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Although initial witness reports stated that the resultant fireball was equivalent to the Hiroshima nuclear explosion, scientific analysis places the force of the blast at anywhere from 100-500 tonnes TNT equivalent—at most, around 3% of Hiroshima's yield. The atomic bombings of Hiroshima and Nagasaki were nuclear attacks near the end of World War II against the Empire of Japan by the United States at This article is about the tonne or metric ton For other tons see Ton. [4]

On September 15, 2007, a chondritic meteor crashed into southeastern Peru near Lake Titicaca, leaving a water-filled hole and spewing gases across the surrounding area. Events 668 - Eastern Roman Emperor Constans II is assassinated in his bath at Syracuse Italy. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Chondrites are stony Meteorites that have not been modified due to Melting or Differentiation of the parent body The Carancas impact event occurred when the Carancas Meteorite fell on September 15, 2007. Peru (Perú Piruw Piruw officially the Republic of Peru ( reˈpuβlika del peˈɾu is a country in western South America. Lake Titicaca is a lake located on the border of Bolivia and Peru. Many residents became ill, apparently from the noxious gases shortly after the impact.

Comet Shoemaker-Levy 9's scar on Jupiter (Dark area at the above-left of the image)
Comet Shoemaker-Levy 9's scar on Jupiter (Dark area at the above-left of the image)

Many impact events occur without being observed by anyone on the ground. Shoemaker-Levy redirects here For other Shoemaker-Levy comets see List of periodic comets. Between 1975 and 1992, American missile early warning satellites picked up 136 major explosions in the upper atmosphere. In the 21-Nov-2002 edition of the journal Nature, Peter Brown of the University of Western Ontario reported on his study of US early warning satellite records for the proceeding 8 years. He identified 300 flashes caused by 1 m to 10 m sized meteors in that time period and estimated the rate of Tunguska sized events as once in 400 years [5]. The Tunguska Event, or Tunguska explosion, was a powerful Explosion that occurred near the Podkamennaya (Lower Stony Tunguska River in what is now Shoemaker estimated that one of such magnitude occurs about once every 300 years, though more recent analyses have suggested he exaggerated by an order of magnitude.

The 1994 impact of Comet Shoemaker-Levy 9 with Jupiter also served as a "wake-up call", and astronomers responded by starting programs such as Lincoln Near-Earth Asteroid Research (LINEAR), Near-Earth Asteroid Tracking (NEAT), Lowell Observatory Near-Earth Object Search (LONEOS) and several others which have drastically increased the rate of asteroid discovery. Shoemaker-Levy redirects here For other Shoemaker-Levy comets see List of periodic comets. The LI ncoln N ear- E arth A steroid R esearch ( LINEAR) project is a cooperative project between the United States Air Force Near Earth Asteroid Tracking (NEAT is a program run by NASA and Jet Propulsion Laboratory to discover Near-Earth objects The NEAT system began observations Lowell Observatory Near-Earth-Object Search (LONEOS was a project designed to discover Asteroids and Comets that orbit near the Earth Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but However, many objects undoubtedly still remain undetected.

Near misses and forecasts

On 19 May 1996 a 300–500 m asteroid, 1996 JA1, passed within 450,000 km of Earth; it had been detected a few days before. Events 1535 - French explorer Jacques Cartier sets sail on his second voyage to North America with three ships 110 men and Year 1996 ( MCMXCVI) was a Leap year starting on Monday (link will display full 1996 Gregorian calendar)

On 18 March 2004 a 30 m asteroid, 2004 FH, passed within 40,000 km of Earth only a few days after it had been detected. Events 37 - The Roman Senate annuls Tiberius ' will and proclaims Caligula emperor "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " TemplateInfobox Planet. --> 2004 FH is a Near-Earth asteroid that was discovered on March This asteroid probably would have detonated in the atmosphere and posed negligible hazard to the surface, had it been on impact course.

On 31 March 2004, a 6 m meteoroid, 2004 FU162 made the closest near miss pass ever observed with a separation of only 1. Events 307 - After divorcing his wife Minervina, Constantine marries Fausta, the daughter of the retired Roman Emperor "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " (also written 2004 FU162) is a Meteoroid which passed within about one Earth radius (~6400 km of the surface of the Earth at 1535 UTC 02 Earth radii from the surface (6,500 km). Because this object is certainly too small to pass through the atmosphere, it is classed as a meteoroid rather than an asteroid.

In 2004, a newly discovered 320 m asteroid, 99942 Apophis (previously called 2004 MN4), achieved the highest impact probability of any potentially dangerous object. TemplateInfobox Planet. --> 99942 Apophis (əˈpɒfɪs previously known by its provisional designation The probability of collision on 13 April 2029 is estimated to be as high as 1 in 17 by Steve Chesley of NASA's Jet Propulsion Laboratory, though the previously published figure was the slightly lower odds of 1 in 37, calculated in December 2004. Events 1111 - Henry V is crowned Holy Roman Emperor. 1204 - The Fourth Crusade sacks Constantinople 2029 ( MMXXIX) will be a Common year starting on Monday of the Gregorian calendar. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program Later observations showed that the asteroid will miss the earth by 25,600 km (within the orbits of communications satellites) in 2029, but its orbit will be altered unpredictably in a way which does not rule out a collision on 13 or 14 April 2036 or later in the century. Events 43 BC - Battle of Forum Gallorum: Mark Antony, besieging Julius Caesar 's assassin Decimus Junius Brutus in 2036 ( MMXXXVI) will be a Leap year starting on Tuesday of the Gregorian calendar. These possible future dates have a cumulative probability of 1 in 45,000 for an impact in the 21st century.

Asteroid 2004 VD17, of 580 m, previously was estimated to have a probability of 1 in 63,000 of striking earth on 4 May 2102 (as of July 2006), with risk 1 on the Torino scale, but further observations lowered the estimate. Events 1256 - The Augustinian monastic order is constituted at the Lecceto Monastery when Pope Alexander IV The Torino Scale is a method for categorizing the impact hazard associated with Near-Earth objects (NEOs such as Asteroids and Comets It is intended as a As of the observation on December 17, 2006, JPL assigns 2004 VD17 a Torino value of 0 and an impact probability of 1 in 41. Events 546 - Gothic War (535–554: The Ostrogoths of King Totila Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. 667 million in the next 100 years.

Asteroid (29075) 1950 DA has a potential to collide with Earth on March 16, 2880. Events 597 BC - Babylonians capture Jerusalem, replace Jehoiachin with Zedekiah as king The 29th century of the Anno Domini ( common) era will span the years 2801–2900 of the Gregorian calendar. The probability of impact is either 1 in 300 or zero, depending on which one of the two possible directions for the asteroid's spin pole is correct. This asteroid has a mean diameter of about 1. 1 km. The energy released by the collision would cause major effects on the climate and biosphere and may be devastating to human civilization. The Atlantic Ocean is predicted to be facing towards the asteroid on the day of the potential collision.

Asteroid 2007 TU24 with an estimated diameter between 300-500-m came very close to earth orbit by 1. Asteroid was discovered by the Catalina Sky Survey in Arizona on October 11, 2007. 4 ld(lunar distance) on January 29, 2008. Events 904 - Sergius III comes out of retirement to take over the papacy from the deposed Antipope Christopher. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common The orbit of the asteroid is shown on NASA's website [6].

Relatively small objects that burn up in the atmosphere can be dangerous beyond their own capabilities. In 2002, U.S. Air Force Brig. Gen. Simon P. Worden told members of a U.S. House of Representatives Science subcommittee that the U. The United States House of Representatives is one of the two chambers of the United States Congress; the other is the Senate. S. has instruments that determine if an atmospheric explosion is natural or man-made, but no other nation with nuclear weapons has that detection technology. He said there is concern that some of those countries could mistake a natural explosion for an attack, and launch nuclear retaliation. In the summer of 2001 U. S. satellites had detected over the Mediterranean an atmospheric flash of energy similar to a nuclear weapon, but determined that it was caused by an asteroid. A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion.

As of March 2008, the Near-Earth Asteroid with the highest probability of impact within the next 100 years is 2007 VK184, with a Torino scale of 1. TemplateInfobox Planet. --> 2007 VK184 is an Asteroid which is listed on the Near Earth Object Risk [10]Impact Risk, Orbital Diagram

End of civilization

An impact event is commonly seen as a scenario[11] [12] that would bring about the end of civilization. This is about the future of civilization humans and the earth In 2000, Discover Magazine published a list of 20 possible sudden doomsday scenarios with impact event listed as the number one most likely to occur. Discover is a Science magazine that publishes articles about Science for a general audience A doomsday event is a specific occurrence which has an exceptionally destructive effect on the human race [13] Until the 1980s this idea was not taken seriously, but all that changed after the discovery of the Chicxulub Crater which was further reinforced by witness to the Comet Shoemaker-Levy 9 event. The Chicxulub Crater (tʃikʃuˈlub is an ancient Impact crater buried underneath the Yucatán Peninsula in Mexico. Shoemaker-Levy redirects here For other Shoemaker-Levy comets see List of periodic comets. Since then there has been more interest from the scientific community and greater public awareness of the possibility of impact events.

Fictional impact events

The impact event has been a plot and background element in science fiction since knowledge of real impacts became established in the scientific mainstream. Interestingly, it seems, by survey, to be one of the less popular themes in apocalyptic science fiction compared to other possible catastrophes.

Numerous science fiction stories and novels center around an impact event; possibly the best selling was the novel Lucifer's Hammer by Larry Niven and Jerry Pournelle. Lucifer's Hammer is a post-apocalyptic Science fiction Novel by Larry Niven and Jerry Pournelle, first published in 1977 Laurence van Cott Niven (born April 30, 1938 Los Angeles California) is a US Science fiction author. Jerry Eugene Pournelle (born August 7, 1933) is an American Science fiction Writer, Essayist and Journalist Arthur C. Clarke's novel Rendezvous with Rama opens with a significant asteroid impact in northern Italy in the year 2077 which gives rise to the Spaceguard Project, which later discovers the Rama spacecraft. Sir Arthur Charles Clarke, CBE (16 December 1917–19 March 2008 was a British Science fiction Author, Inventor, and Rendezvous with Rama is a novel by Arthur C Clarke first published in 1972. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest In 1992 a Congressional study in the U. S. A. led to NASA being directed to undertake a 'Spaceguard Survey' (with the novel being named as the inspiration for the name[7]) to search for Earth-impacting asteroids. The term Spaceguard loosely refers to a number of efforts to discover and study Near-Earth objects (NEO This in turn inspired Clarke's 1993 novel The Hammer of God. The Hammer of God is a Science fiction Novel written by Arthur C A variation on the traditional impact story was provided by Jack McDevitt's 1999 novel Moonfall, in which a very large comet travelling at interstellar velocities collides with and partially destroys the Moon, fragments of which then collide with the Earth. Jack McDevitt (born 1935 is an award-winning American science fiction author whose novels frequently deal with attempts to make Contact with alien

Several disaster movies have also been made: When Worlds Collide (1951), deals with a planet and small sun on a collision course with Earth - the planet a "near miss," causing extensive damage and destruction, followed by a direct hit from the sun. A disaster film is a movie genre that has an impending or ongoing Disaster (such as a damaged Airliner, Fire When Worlds Collide is a 1951 Science fiction film based on the 1932 novel co-written by Philip Gordon Wylie and Edwin Balmer Meteor (1979) features small asteroid fragments and a large five-mile-wide asteroid heading for Earth. Meteor is a 1979 Disaster film in which scientists detect an Asteroid on a collision course with Earth and struggle with international Orbiting US and Soviet nuclear weapons platforms are turned away from their respective earthbound targets, and towards the incoming threat. In 1998, two films were released in the United States on the subject of attempting to stop impact events: Touchstone Pictures' Armageddon, about an asteroid; and Paramount/DreamWorks' Deep Impact, about a comet. The United States of America —commonly referred to as the Touchstone Pictures is one of several alternate Film labels of The Walt Disney Company, established in 1984 Armageddon is a 1998 disaster / sci-fi - action film about a group of blue-collar deep-core drillers who are Paramount Pictures Corporation is an American motion picture production and Distribution company, based in Hollywood California. DreamWorks LLC, also known as DreamWorks Pictures, DreamWorks SKG, or DreamWorks Studios, is a major American Film studio Deep Impact is a 1998 sci-fi - drama Disaster film released by Paramount Pictures and DreamWorks SKG in the Both involved using Space Shuttle-derivative craft to deliver large amounts of nuclear weapons to destroy their targets. NASA 's Space Shuttle, officially called the Space Transportation System ( STS) is the Spacecraft currently used by the United States A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. Also in 1998, the award-winning Canadian film Last Night described the behavior of several characters anticipating the end of the world due to some certain but unstated peril with a known due date - thus resembling a civilzation terminating impact event. Last Night is a 1998 Canadian film by Don McKellar. It was filmed in Toronto.

In 1968, a Star Trek episode entitled "The Paradise Syndrome" involved the crew of the Starship Enterprise endeavoring to alter the trajectory of a moon-sized asteroid so as to prevent a disastrous collision with a planet that lie in its path. Interestingly, the inhabitants of the doomed planet are represented by a culture indistinguishable from the pre-Columbian Indians of North America.

Also in 1968, a joint Japanese-American venture between Toei and MGM resulted in the release of The Green Slime which chronicled the exploits of a group of astronauts as they race to rendezvous with an asteroid on a collision course with Earth. () is a Japanese film and Television production and distribution Corporation. is a 1968 Science-fiction film directed by Kinji Fukasaku. It was co-produced by the Toei Company in Japan and MGM in the The astronauts touch down on the surface of the asteroid where they proceed to plant a powerful explosive device that disintegrates the object.

A small impact event in the Command & Conquer: Tiberian series of videogames caused the deadly mineral Tiberium to arrive on Earth near Italy's Tiber River, in 1995. The Command & Conquer Tiberian series is a sub-series of Real-time strategy Video games belonging to the extensive Command & Conquer franchise Tiberium is a Fictional Crystalline substance of extra-terrestrial origins featured prominently in the Tiberium story arc of the Command Other meteorites may have contributed to the spread of Tiberium.

Many Impacts occur on differing planets in the Metroid Prime series, though these meteorites were actually vessels of Phazon corruption, called Leviathans. Metroid Prime is a Video game developed by Retro Studios and published by Nintendo for the Nintendo GameCube, released in North America

The Outpost series of videogames revolves around a major impact event that annihilates Earth, and the player must rebuild on a different planet, as Earth is rendered uninhabitable.

The Nintendo DS game Advance Wars: Days of Ruin is set in a post apocalyptic world where 90% of the population has been wiped out due to a meteor shower. Advance Wars Days of Ruin (known as Advance Wars Dark Conflict in Europe and Australia and Famicom Wars DS 2 in Japan is

Notes

  1. ^ Permian Extinction
  2. ^ Ancient Crash, Epic Wave by Sandra Blakeslee, New York Times, 14 Nov 2006
  3. ^ Meteor 'misfits' find proof in sea. Retrieved on 2006-11-14. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1533 - Conquistadors from Spain under the leadership of Francisco Pizarro arrive in Cajamarca, Inca
  4. ^ Meteorite Impact Structures Student Research
  5. ^ Ceplecha, Z. (1961) Multiple fall of Pribram meteorites photographed. Bull. Astron. Inst. Czechoslovakia, 12, 21-46 NASA ADS
  6. ^ McCrosky, R. E. et al. (1971) J. Geophys. Res. 76, 4090-4108
  7. ^ Campbell-Brown, M. D. and Hildebrand, A. (2005) A new analysis of fireball data from the Meteorite Observation and Recovery Project (MORP). Earth, Moon, and Planets 95, 489 - 499
  8. ^ Oberst, J. et al. (2004) The multiple meteorite fall of Neuschwanstein: Circumstances of the event and meteorite search campaigns. Meteoritics & Planetary Science 39, 1627-1641 NASA ADS
  9. ^ Grand Teton Meteor Video
  10. ^ Current Impact Risk (NEO JPL NASA)
  11. ^ Armageddon Online. Possible end-of-civilization scenarios. (Warning: Pop-ups)
  12. ^ Exit Mundi. Possible-end-of-civilization scenarios. (Warning: Pop-ups)
  13. ^ "Twenty ways the world could end suddenly". Discover Magazine. Discover is a Science magazine that publishes articles about Science for a general audience

See also

Further reading

External links

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