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Topic: Impact event


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  Impact Cratering on Earth
For impact events on Earth that form craters larger than approximately 1 km across, the pressures and temperatures produced upon impact are sufficient to completely melt and even vaporize the impacting body and some of the target rocks, though a small fraction of the impactor can locally be preserved for even the largest impacts.
The tendency to discount impact processes as a factor in the Earth's more recent geologic history was severely challenged by the interpretation in 1980 that Cretaceous-Tertiary (K-T) boundary sediments world-wide were due to a major impact event and that impact was the causal agent for a mass extinction event.
The Tunguska event in 1908 was due to the atmospheric explosion of a relatively small, approximately few tens of metres, body at an altitude of 10 km.
www.unb.ca /passc/ImpactDatabase/essay.html   (2144 words)

  
 Terrestrial Impact Craters Slide Set
Impact cratering research has gained attention throughout the world following the suggestion that a large impact event caused the extinction of about 50% of all living species, including the dinosaurs, approximately 65 million years ago.
Based on apparent correspondences between periodicities observed in the marine extinction record and in the terrestrial impact record, some scientists have suggested that large meteorite impacts might be the metronome that sets the cadence of biological evolution on Earth —; an unproved but intriguing hypothesis.
Impact craters are formed when a large meteoroid (asteroid or comet) crashes into a larger planetary body that has a solid surface.
www.lpi.usra.edu /publications/slidesets/craters/index.shtml   (1908 words)

  
 Impact event - Wikipedia, the free encyclopedia
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.
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.
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.
en.wikipedia.org /wiki/Impact_event   (3110 words)

  
 Geological Society of America - GSA Today - v. 10, no. 8, August 2000   (Site not responding. Last check: 2007-10-11)
The biologic consequences of impact cratering depend on many factors, including the energy of the impact event, the type of target materials, the type of projectile, and the ambient conditions on Earth at the time of impact.
Impact cratering is a very energetic geologic process that has the capability of disrupting or redirecting the biologic evolution of a planet.
In the case of the Chicxulub impact event 65 Ma, a large number of regional and global environmental effects were generated that were likely the cause of the mass extinction that marks the K-T boundary.
www.geosociety.org /pubs/gsatoday/gsat0008.htm   (4104 words)

  
 PSR Discoveries: Hot Idea: Damage by Impact at Meteor Crater
Winds in excess of 1000 km/hour scoured the land within 3 to 5 km of the point of impact and led to swift devastation of the local population of plants and animals.
Since no one has ever observed the production of an impact crater on any rocky planet, we must use the size and shape of the craters, the presence of excavated bedrock, the shape and extent of the ejecta, and over-turned rock layers in the crater rims to understand the cratering process.
Researchers are gaining more understanding of the interplay between impact energy, target rock strength and structure, presence or absence of volatiles, and gravity from their studies of impact craters throughout the Solar System.
www.psrd.hawaii.edu /Dec97/impactBlast.html   (2150 words)

  
 Armageddon Online - Asteroid Impacts & Meteor Impacts - Impact Events
There is no solid evidence of impacts leading to the four other major mass extinctions, though many scientists assume that they are at least related to impacts.
This would be the final piece of evidence that convinced the vast majority of scientists that this extinction resulted from a point event that is most probably an extra-terrestrial impact and not from increased volcanism and climate change (which would spread its main effect over a much longer time period).
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.
www.armageddononline.org /impact_event.php   (1760 words)

  
 PSRD Hot Idea: Impact at the end of the Permian
This led Becker and her colleagues to conclude that impact of a 9-kilometer asteroid deposited the buckyballs.
This led Alvarez to propose that the enrichment is due to an asteroid or comet impact.
Studies of the ages of impact craters on Earth and the number of asteroids in orbits that cross Earth's orbit indicate that impactors 10 kilometers or larger hit the Earth once every 100 million years.
www.psrd.hawaii.edu /Feb01/permianImpact.html   (1833 words)

  
 How Dangerous are Earth-Crossing Objects?
Asteroid/Comet Earth Impacts by David A. Rideout calculates the approximate kinetic energy of an asteroid and a comet released on impact with the Earth.
Tectonic Interpretation Of The 1908 Tunguska Event by Andrei Yu Ol'khovatov suggests that the Tunguska event was entirely seismic in nature and not the result of an impact event.
Tunguska Meteorite Paradox (1908-1998) by A. Zlobin suggests the Tunguska event was caused by significant magnetohydrodynamic effects from the destruction of a comet fragment in the atmosphere.
www.pibburns.com /catastro/impacts.htm   (6417 words)

  
 IMPACT Muang Thong Thani - IMPACT Arena, Exhibition & Convention Center
IMPACT Muang Thong Thani comprises of the 4,000-square-meter flat floored IMPACT Arena; the 47,000-square-meter IMPACT Exhibition Center; and the 30,000-square-meter IMPACT Convention Center.
IMPACT Muang Thong Thani was established in 1998 when Bangkok Land Public Company Limited built the Muang Thong Thani Stadium as one of the three official sport stadiums to host the 13 th Asian Games.
IMPACT Convention Center was built in 2000 to cope with the increasing demand for convention and conference space.
www.impact.co.th /history.php   (659 words)

  
 Terrestrial Impact Cratering and Its Environmental Effects
Impact events have even affected the atmospheres of the giant gaseous planets, as exemplified by the impact of comet Shoemaker-Levy 9 with Jupiter in 1994, which produced Earth-size blotches in the atmosphere.
Perhaps the most infamous of these impact craters is the ~180 km diameter Chicxulub impact crater on the Yucatan Peninsula of Mexico.
Studies of the Chicxulub impact event and the mass extinction event that occurred on Earth 65 million years ago have demonsrated that impact cratering can affect the biologic evolution of a planet as well as the geologic evolution of a planet.
www.lpl.arizona.edu /SIC/impact_cratering/intro   (384 words)

  
 Armageddon Online - Asteroid Impacts & Meteor Impacts with Earth
This event threw huge amounts of matter into the atmosphere in addition to this, it caused 2000 foot waves that may have all but completely emptied the Gulf of Mexico.
This event created months of darkness (which interfered with photosynthesis) and much cooler temperatures globally, and the resulting harsh conditions which in turn led to the extinction of many species, including the last of the dinosaurs.
It is an estimate that impacts of asteroids as large as the one thought responsible for the K-T extinction occur about once every hundred million years.
www.armageddononline.org /asteroid.php   (1352 words)

  
 The Chiemgau-Impact
That impact struck the south-east of Bavaria/Germany at some time during the Celtic period and left an extended crater-strewnfield of about 100 craters.
Bones and teeth from the impact layer (ejecta, Bunte breccia) at Lake Tüttensee (Chiemgau impact event).
It is left to assumptions whether the animals perished on impact or whether the skeletons existed already and were smashed and intermixed in the impact breccia.
www.chiemgau-impact.com   (709 words)

  
 The KT-boundary Impact
Debris from the explosion was thrown into the atmosphere, severely altering the climate, and leading to the extinction of roughly 3/4 of species that existed at that time, including the dinosaurs.
During the impact, the kinetic energy in the asteroid (or energy of motion) is converted to explosive energy, blowing debris of dust, soil, and rocks not only into the atmosphere, but out into space, where it fell back into the top of the atmosphere.
Impacts big enough to wipe out many species occur only every 100 My or so, so it is unlikely that we or even our great-great-grandchildren will see one.
www.psi.edu /projects/ktimpact/ktimpact.html   (2145 words)

  
 Ignition Threshold For Impact-Generated Fires
Their research indicates that impacts resulting in craters at least 85 kilometers wide can produce continental-scale fires, while impact craters more than 135 kilometers wide are needed to cause global-scale fires.
To calculate the threshold size impact required for global ignition of various types of vegetation, Durda and Kring used two separate, but linked, numerical codes to calculate the global distribution of debris reentering the atmosphere and the kinetic energy deposited in the atmosphere by the material.
The distribution of fires depends on projectile trajectories, the position of the impact relative to the geographic distribution of forested continents and the mass of crater and projectile debris ejected into the atmosphere.
www.spacedaily.com /news/deepimpact-04m.html   (680 words)

  
 News Article: Evidence for a Large Impact at the Permian-Triassic Boundary   (Site not responding. Last check: 2007-10-11)
Both the KT and the PT event have been associated with large volcanic eruptions, although the time scale for volcanism is millions of years, not the thousands of years (or less) that account for the great dying.
He noted that while the evidence for an impact at the PT has been growing over the past couple of years, he would still not be able to say that an impact was more likely than a volcanic explanation, or perhaps some other cause.
Seismic imaging, gravity data and the identification of melt rocks and impact breccias from drill cores located on top of Bedout are consistent with the presence of a buried impact crater.
nai.arc.nasa.gov /impact/news_detail.cfm?ID=142   (2056 words)

  
 impact event concept from the Astronomy knowledge base   (Site not responding. Last check: 2007-10-11)
extinction level event (3 facts) - impact event which can cause the extinction of many species on a planet
The term "fireball" is sometimes used for a meteor approaching the brightness of Venus; the term "bolide" for one approaching the brightness of the full Moon.
meteor event (7 kinds, 28 facts) - The event in a sequence of the events during the passage of a meteor.
www.site.uottawa.ca:4321 /astronomy/impactevent.html   (259 words)

  
 ESA Portal - Preparing for impact
Although dramatic images of the impact may be sent to Earth in near-real time by the Deep Impact spacecraft and its impactor, the spacecraft themselves have limited remote sensing capability.
The parent spacecraft will observe the impact from 500 kilometres distance, and then turn to look at the other side of the nucleus, but most of the observations of the event will be carried out by other spacecraft and from Earth.
It is essential to have a good set of observations before the impact to unambiguously distinguish the effects of the impact from the natural activity of the comet.
www.esa.int /esaCP/SEM8PE0DU8E_index_0.html   (580 words)

  
 Tunguska event - Wikipedia, the free encyclopedia
In recent history, the Tunguska event stands out as one of the rare large-scale demonstrations that a full doomsday event is a real possibility for the human race.
In 1965, Cowan, Atluri, and Libby suggested that the Tunguska event was caused by the annihilation of a chunk of antimatter falling from space.
Russian mineralogist Leonid Kulik identified the place of impact in a forest near the Podkamennaja River (coordinates 60° 53' 40" N latitude and 101° 53' 40" E longitude.) Between 1921 and 1938 Kulik organized 5 expeditions to the area, but neither a crater nor other evidence of the impact was found.
en.wikipedia.org /wiki/Tunguska_event   (4230 words)

  
 Ernstson Claudin impact structures
A comprehensive report on the Rubielos de la Cérida impact basin and crater chain (Spain) including 170 new images (outcrops, impact breccia samples, impact melt rocks, photomicrographs of shock metamorphism) tables and diagrams.
Amazingly similar: Regmaglypts on the surface of the Tabor meteorite and on a limestone clast from the Puerto Mínguez impact ejecta.
The university of Zaragoza denies the existence of the impact of a meteorite.
www.impact-structures.com   (506 words)

  
 United Methodist Women's Legislative Event | Texas Impact
The Texas United Methodist Women’s Legislative Event is a national model educational program that brings together women of all ages and backgrounds to learn more about how their state government works and how they can be active, informed citizens.
Texas Impact works with UMW year round to produce Legislative Event and ensure up-to-the-minute Texas public policy information in the context of United Methodist Social Principles.
Special guests at the event included Bishop Joel Martinez of the Southwest Texas Annual Conference UMC, Reverend George Joehnk of Methodist Healthcare Ministries of South Texas, Huston-Tillotson University vice-president Dr. Vicki Minor, Texas Impact president Reverend Mel Caraway, and Texas Impact past president and former executive director Lin Team.
texasimpact.org /drupal/umw   (868 words)

  
 impact event Comparison Table   (Site not responding. Last check: 2007-10-11)
impact event which can cause the extinction of many species on a planet
A "shooting star" - the streak of light in the sky produced by the transit of a meteoroid through the Earth's atmosphere; also the glowing meteoroid itself.
The event in a sequence of the events during the passage of a meteor.
www.site.uottawa.ca:4321 /astronomy/impactevent_table.html   (137 words)

  
 Appendix B - The K-T Event
Then in 1980, Alvarez, Alvarez, Asaro, and Michel reported their discovery that the peculiar sedimentary clay layer that was laid down at the time of the extinction showed an enormous amount of the rare element iridium.
The high temperatures generated by the impact would have caused enormous fires, and indeed soot is found in the boundary clays.
The impact of a 10-kilometer (6 mile) asteroid would most certainly have been an enormous insult to life on Earth.
www.solarviews.com /eng/comet/appendb.htm   (565 words)

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