ارتطام (فلك)

الإرتطام أو الصدم impact مصطلح يشير الى لحظة ارتطام حجر نيزكي بسطح الكرة الأرضية فاذا كانت سرعة حركة الحجر النيزكي شديدة فالفوهة الناتجة عن قوة الإرتطام ستكون كبيرة وواسعة. الجدير بالذكر أن معظم الفوهات المنتشرة على سطوح القمر وعطارد والمريخ هى ذات أصل نيزكي ضربتها أحجار نيزكية كبيرة قادمة من أماكن محددة من النظام الشمسي وخاصة حزام الكويكبات .

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, one after another.

Eugene Merle Shoemaker was first to prove that meteor impacts have affected the Earth.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

 حوادث ارتطام قريبة قبل التاريخ

Aerial view of Barringer Crater in Arizona

• Barringer Crater in the USA, the first crater to be proven the result of an impact
• the Rio Cuarto craters in Argentina, produced by an asteroid striking Earth at a very low angle around 10,000 years ago
• the Henbury crater in Australia, and Kaali crater in Estonia, apparently produced by objects which broke up before impact. Both are estimated to be 4000-5000 years old.
• the Wabar craters in Arabia, which may have been created sometime during the past few hundred years

 حوادث الارتطام الحديثة

Trees knocked over by the Tunguska blast.

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

 الاقترابات الشديدة والتوقعات

انظر أيضاً: كويكب قرب الأرض and جرم قرب الأرض

On May 19, 1996 a 300-500 m asteroid, 1996 JA1, passed within 450,000 km of Earth; it had been detected a few days before.

 انظر أيضا

• فوهة
• حزام الكويكبات
• كويكب
• Asteroid deflection strategies
• B612 Foundation
• Earth Impact Database
• Extinction event
• Hypothetical future disasters
• Impact crater
• Impact gardening
• Near-Earth asteroids
• Near-Earth objects
• Pan-STARRS
• Potentially hazardous asteroid
• Spaceguard
• Torino scale

 المصادر

• مؤمن, عبد الأمير (2006). قاموس دار العلم الفلكي. بيروت، لبنان: دار العلم للملايين. {{cite book}}: Cite has empty unknown parameter: |طبعة أولى coauthors= (help)

 للاستزادة

• Alvarez L.W, Alvarez W., Asaro F., Michel H.V. (1980) Extraterrestral Cause for the Cretaceous-Tertiary Extinction, Science 208, 1095-1108.
• Blakeslee, Sandra (2006) Ancient Crash, Epic Wave, New York Times, November 14, 2006.
• Shukolyukov A., Lugmair G.W. (1998) Isotopic Evidence for the Cretaceous-Tertiary Impactor and Its Type, Science 282, 927-929.
• Smit J., Hertogen J. (1980) An extraterrestrial event at the Cretaceous-Tertiary boundary, Nature 285, 198-200.
• Stone R.:'" Target earth" National Geographic Magazine August 2008
• Michael J. Benton, When Life Nearly Died: The Greatest Mass Extinction of All Time, Thames and Hudson, 2003.

 وصلات خارجية

• EARTH IMPACTS from Greg Goebel's IN THE PUBLIC DOMAIN
• Earth Impact Database
• Earth Impact Effects Program
• Nature journal video discussing historical impact event on Mars
• Aerial Explorations of Terrestrial Meteorite Craters
• All 172 confirmed meteor impact sites on earth, viewable in Google Earth (Largest, Most recent, Per continent, Including size indicator)
• Reorienting Western Society to Battle Impact Events Jagiellonian University, Poland
• A comet or asteroid impact with the earth - How real is the threat? Bob Hawkes
• arguing for a globally cooperative Earth Defense Initiative (EDI)
• Traces of Catastrophe
• GEOSIM - Information on impact processes and effects; 3-D-simulation
• Down 2 Earth Impact Calculator Interactive simulator showing size of craters on Google Maps
• Impact Site Map Interactive map, with simple html drilldowns to Google satellite maps of impact sites.