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Topic: Impact

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  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   (2338 words)

 Terrestrial Impact Craters
Impact craters are geologic structures formed when a large meteoroid, asteroid or comet smashes into a planet or a satellite.
The impact basin is buried by several hundred meters of sediment, hiding it from view.
The Manicouagan impact structure is one of the largest impact craters still preserved on the surface of the Earth.
www.solarviews.com /eng/tercrate.htm   (2496 words)

 Impact crater -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-11-07)
Although it might be assumed that a major impact on the Earth would leave behind absolutely unmistakable evidence, in fact the gradual processes that change the surface of the Earth tend to cover the effects of impacts.
Impact craters are found on nearly all solid surface planets and satellites.
The distinctive mark of an impact crater is the presence of rock that has undergone shock-metamorphic effects, such as shatter cones, melted rocks, and crystal deformations.
www.absoluteastronomy.com /encyclopedia/i/im/impact_crater.htm   (2818 words)

 Impact Craters of the Earth   (Site not responding. Last check: 2007-11-07)
The impact craters are quickly eroded from the surface and the best preservation of these is in the most stable regions on the shields and cratons (oldest, stable parts of continents).
Twenty-five impact structures are known on the Canadian Shield, 19 craters are spread in Australia, and 7 craters are situated on the Ukrainian Shield over a territory of about 250,000 km2.
The most ancient terrestrial impact craters are presented by two gigantic astroblemes: the Vredefort crater in South Africa, about 2 billion years old and 140 km in diameter, and the Sudbury astrobleme in Canada, 1.85 billion years old.
www.meteor.co.nz /aug96_2.html   (1001 words)

 Thomson ISI - The Impact Factor: Institute for Scientific Information   (Site not responding. Last check: 2007-11-07)
The impact factor is one of these; it is a measure of the frequency with which the "average article" in a journal has been cited in a particular year or period.
Thus, the impact factor of a journal is calculated by dividing the number of current year citations to the source items published in that journal during the previous two years (see Figure 1).
The impact factor should not be used without careful attention to the many phenomena that influence citation rates, as for example the average number of references cited in the average article.
www.isinet.com /isi/hot/essays/journalcitationreports/7.html   (1873 words)

 Meteor Impact Craters
Over 150 impacts have been studied on the earth, though the true number will never be known.
During impact, debris is thrown from the crater.
This peak is caused by the surface's attempt to rebound from the impact.
liftoff.msfc.nasa.gov /Academy/SPACE/SolarSystem/Meteors/Craters.html   (332 words)

 Great Impact Debate I: Benefits of Hard Bodies :: Astrobiology Magazine :: Search for Life in the Universe
Some articles in petroleum-science journals claim that impacts, like the Chicxulub impact 65 million years ago, break up subterranean rocks and provide regions where oil is likely to collect.
In the 17th century, Isaac Newton was the first to suggest that cometary impacts were essential for the preservation of the world since they "refurbished" and "replenished" the planets, the sun, and the stars.
Irrespective of the uncertainty, or lack of evidence, that impacts are associated with other mass extinctions, from what we now know it is entirely plausible that impacts could have caused most mass extinctions.
www.astrobio.net /news/article373.html   (3717 words)

 BBC News | SCI/TECH | Impact led to dino rule
The impact of an extraterrestrial object may have led to the downfall of the dinosaurs, but now it seems another, much earlier collision, could have been the factor that allowed the great beasts to rise to prominence in the first place.
He suggested that the effects of the impact killed off or reduced many competitive species, clearing the way for dinosaurs to adapt and flourish.
Many scientists now believe a massive impact off the Yucatan peninsula in Mexico 65 million years ago (the end of the Cretaceous) transformed the Earth's climate, making it impossible for the dinosaurs to continue; it was mammals on that occasion which took advantage.
news.bbc.co.uk /hi/english/sci/tech/newsid_1991000/1991444.stm   (722 words)

 Deep Impact
The Deep Impact mission was a partnership between the University of Maryland (UMD), the California Institute of Technology's Jet Propulsion Laboratory (JPL) and Ball Aerospace and Technology Corp. The scientific leadership of the mission was based at UMD.
The flyby spacecraft carried the primary imaging instruments (the HRI and MRI telescopes) and the impactor (with an ITS telescope) to the vicinity of the comet nucleus.
The energy from the impact was to excavate a crater approximately 100 m wide and 28 m deep.
www.astronautix.com /craft/deempact.htm   (1600 words)

 Athena Review 2,1: Impact craters on Venus
They are clearer examples of the same types of impact features that occur on Earth, a planet of nearly the same size and gravity as Venus but unlike it, covered with eons of the remains of biological life and terrestial weathering.
Impact craters comparable to that at Chicxulub include the Strindberg Crater on Mercury, and the the multi-ringed Klenova impact basin on Venus.
The Rochechouart impact in France, along with the Manicouagan crater in Quebec and the Saint Martin impact structure in Manitoba would have had a combined impact strength of the object which struck Chicxulub.
www.athenapub.com /venus1.htm   (1444 words)

 Cosmic Impacts: Is the Sky Falling? (Skeptical Inquirer May 1997)
Most scientists first thought about the role of impacts in Earth history in response to the now-famous paper published in Science in 1981 by Luis and Walter Alvarez and their colleagues, suggesting that an impact sixty-five million years ago produced the mass extinction that terminated the Cretaceous era.
Impacts are the ultimate environmental disasters, more important than volcanic eruptions or other more familiar events in shaping the history of life on the planet.
He was among the first to publish research on the contemporary impact hazard, and he chaired the congressionally mandated 1992 NASA study of ways to carry out a comprehensive survey of potentially threatening comets and asteroids.
www.csicop.org /si/9705/asteroid.html   (5133 words)

 Welcome to The Impact Fund
The Impact Fund is a public foundation dedicated to providing representation, technical assistance and funding for complex, public interest litigation.
The Discrimination Research Center is a leading non-profit, civil rights think tank utilizing a variety of social science research methodologies to measure discrimination in employment, public services and other aspects of daily life.
The Impact Fund is leading the charge against gender discrimination in the retail industry.
www.impactfund.org   (323 words)

 A presentation skills training, phone skills and communication skills training company.
Impact Communications is a national communication skills training and presentation skills training organization that partners with Fortune 1000 companies, large privately-held organizations and government agencies.
Impact Communications’ communication skills training, phone skills and presentation skills training programs will insure that the professionals in your organization become powerful business communicators.
Judy Filek, President of Impact Communications, Inc. has written an article that was published in the May/June 2003 issue of MX Magazine.
www.impactcommunicationsinc.com   (331 words)

 Adding up the risks of cosmic impact - Space News - MSNBC.com
He referred to an impact event in the Rio Cuarto region of northern Argentina, in which an asteroid 100 to 300 yards (or meters) in diameter apparently broke up as it zoomed through the atmosphere, leaving a trail of craters.
When compared with total deaths during the same time frame, impact-related fatalities generally worked out to far fewer than 1 in 10,000, which he said was consistent with the view that asteroids and comets were a significant but not a major cause of death.
For instance, small-scale impacts — along with increased levels of cosmic dust in the atmosphere — could have contributed to climate changes, he said.
www.msnbc.com /news/373938.asp   (1308 words)

 Asteroid or comet triggered death of most species 250 million years ago
The researchers estimate the comet or asteroid was 6 to 12 kilometers across, or about the size of the asteroid that left the huge Chicxulub crater near what is now the town of Progresso on Mexico's Yucatan Peninsula 65 million years ago.
That impact is believed responsible for the extinction of the dinosaurs.
While the findings illustrate that impact with large space bodies can be detrimental to life on Earth, Becker noted that there also is evidence they might have been key to life starting here in the first place.
www.washington.edu /newsroom/news/2001archive/02-01archive/k022201.html   (923 words)

 MIAC - Impact Craters   (Site not responding. Last check: 2007-11-07)
The impact that produced this crater occurred about 1.4 million years ago, that is just before the glaciers covered this area.
The location of this crater is 19°10'S, 127°46'E. The rim diameter is 800 m and the distance from the rim crest to the present crater floor is 60 m.
However, the huge landslides that follow most impacts, as the sides of the crater slip into the hole, have usually changed their orientation.
dsaing.uqac.uquebec.ca /~mhiggins/MIAC/impact.htm   (701 words)

 Home - Impact   (Site not responding. Last check: 2007-11-07)
Impact believe that organisations and communities can and should be brought together for mutual benefit and learning.
Impact becomes a signatory of the United Nations Global Compact...
Impact and English Cricket — The vision becomes reality...
www.impact-dtg.com   (158 words)

 Comparing the Impact of Open Access (OA) vs. Non-OA Articles in the Same Journals
The way to test the impact advantage of Open Access (OA) is not to compare the citation impact factors of OA and non-OA journals but to compare the citation counts of individual OA and non-OA articles appearing in the same (non-OA) journals.
It is certainly welcome news that there are no impact differences between the 191 OA journals and the 8509 non-OA journals indexed by ISI, equating for comparable journals as closely as possible: .
Garfield, E. (1998) The use of journal impact factors and citation analysis in the evaluation of science.
www.dlib.org /dlib/june04/harnad/06harnad.html   (1200 words)

 Impact Sockets, Power Socket Striking and Slugging Wrenches - PowerMaster
All Impact Sockets are made from high strength alloy steel.
The Freecorner profile is provided on the square drives as well as on the hexagon end of Impact Sockets 1/2" square drive and above.
Elimination of high stress concentration points increasing the impact resistance and the torque transmitting capability.
www.impactsocket.com   (211 words)

 Earth Impact Craters
Large impacts have beyond a doubt played an important role in the development and evolution of life on Earth.
The distribution of glassy secondary micrometeorites known as tektites, and ejecta debris on the North American continent eventually pinpointed a large sub-surface crater on the coast of Yucatan in Mexico.
This is a relatively recent crater (~49,000 yrs), and although it is very impressive to stand on its' edge and look across to the far rim, that rim is only 1.2 km away.
exobio.ucsd.edu /Space_Sciences/earth_impact_craters.htm   (713 words)

 Deep Impact (1998)   (Site not responding. Last check: 2007-11-07)
Deep Impact is an excellent film that tells the story of a giant comet that is heading towards earth and unless it is stopped it will destroy everything.
One of the things that I admired so much about this film was how Tea Leoni was so hell bent on uncovering a story so that she could move up in the ranks of reporting, and in the process she uncovers something bigger than any political scandal could ever be.
Deep Impact is more than just a movie, it is an experience, and one that should be had by all.
www.imdb.com /title/tt0120647   (914 words)

 Meteorites, Meteorites and Impacts
A more recent impact occurred in 1908 in a remote uninhabited region of western Siberia known as Tunguska.
Larger ones are less numerous and impacts are less frequent, but they do sometimes happen and with disastrous consequences.
The impact of a comet or asteroid about the size of Hephaistos or SL9 hitting the Earth was probably responsible for the extinction of the dinosaurs 65 million years ago.
seds.lpl.arizona.edu /nineplanets/nineplanets/meteorites.html   (1499 words)

 1908 SIBERIA EXPLOSION: Reconstructing an Asteroid Impact from Eywitness Accounts
It was caused by the impact and breakup of a large meteorite, at an altitude roughly six kilometers in the atmosphere.
A key to the phenomenon is: the larger the impact the rarer it is. An Air Force satellite in the 1990s detected a smaller explosion over the Pacific.
Thus, it seems at least plausible that large explosions of meteoritic objects were among the celestial events (together with smaller meteorite impacts, auroras, hurricanes, storms, and floods) that gave rise to belief in capricious god-like forces acting from the skies.
www.psi.edu /projects/siberia/siberia.html   (2519 words)

 Potsdam Institute for Climate Impact Research   (Site not responding. Last check: 2007-11-07)
PIK is an international and independent research institute working on questions of climate change, climate impact and sustainable development.
The 2003 European heat wave and drought had a massively negative impact on growth in European ecosystems.
This has been shown by researchers at the Potsdam Institute for Climate Impact Research in a study exploring the stability of the Indian monsoon.
www.pik-potsdam.de   (189 words)

 Lecture 23 - Impact Theory of Mass Extinction
Thus, they argued that this Ir-enriched layer was caused by the impact of a giant asteroid (~10 km) that put enough dust into the upper atmosphere to darken and hence cool the Earth for several years.
The impact structure, discovered buried beneath the shore of the Yucatan Peninsula (Chicxulub), turns out to be from 150 - 300 km in diameter, possibly the largest impact known in the world and said by some to be the largest known in the solar system.
Debate still rages by paleontologists about whether the impact was directly the cause of the extinction itself, or merely the coup de grace.
rainbow.ldeo.columbia.edu /courses/v1001/23.html   (1556 words)

 SPACE.com -- Lunar Crash of 1953: Impact Crater Identified
So tiny, in fact, it's not visible from Earth or on images taken by the Lunar Orbiter probes dispatched to the Moon in preparation for the Apollo lunar landing expeditions, she added.
Buratti and Johnson estimate that the energy of the impact event was about 0.5 megatons, resulting in the newly found feature.
The radius of the impacting body was over 65-feet (20 meters).
www.space.com /missionlaunches/lunar_impact_021214.html   (581 words)

 Urban IMPACT: Projects
Urban IMPACT develops and participates in numerous activities in the effort to achieve its goals.
IMPACT Project schedules and discussions are available in the
Urban Impact Project, The University of Tennessee at Chattanooga.
www.utc.edu /Outreach/UrbanImpact/projects/projects.html   (248 words)

 Appendix B - The K-T Event
The high temperatures generated by the impact would have caused enormous fires, and indeed soot is found in the boundary clays.
Such an impact would cause enormous tidal waves, and evidence of just such waves at about that time has been found all around the Gulf of Mexico.
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)

 Dam-Reservoir Impact & Information Archive: DRIIA; peer-reviewed, grey literature, bibliographic and other information ...   (Site not responding. Last check: 2007-11-07)
In what is no big surprise to anyone who has been studying the field of hydro impacts for more than a decade New Scientist is at long last reporting that hydroelectric generation is no more benign than coal-fired energy plants are.
Hydro impact reseachers have known this since the early 1990's, when John Rudd and his colleagues reported their groundbreaking findings on greenhouse gas emissions and Canadian hydroelectric reservoirs.
They foolishly intend to fly in the face of 30 odd years of impacts literature and the laws of physics, never mind compassion for the people their projects will oust, and intend to take their, uh, case to the International Court in the Hague, despite no scientific legs for it to stand upon.
www.sandelman.ottawa.on.ca /dams   (3699 words)

 IMPACT Trade Union
If you're an IMPACT member, this site will give you key information about your rights at work and tell you more about what the union is doing on your behalf.
If you're not an IMPACT member yet, our web pages will show you many of the benefits that more than 54,000 of our members enjoy.
Hundreds of thousands of Irish workers have discovered that membership of a trade union brings better pay and working conditions and a strong and skilful friend if problems arise at work.
www.impact.ie   (235 words)

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