FINAL IMPACT

Wallpaper Description:

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.
The most significant recorded impact in recent 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 kilometers (3–6 mi) above the Earth's surface, felling an estimated 80 million trees over 2,150 square kilometers (830 sq mi). But 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. 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. Another fireball blew up over the Australian town of Dubbo in April 1993, shaking things up but causing no harm.
A small number of meteorite falls have been observed with automated cameras and recovered following calculation of the impact point. The first of these was the Pribram 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 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. 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 Pribram, led to the discovery and orbit calculations for the Neuschwanstein meteorite in 2002.

The only reported fatality from meteorite impacts is an Egyptian dog who was killed in 1911, although this report is disputed. The meteorites that struck this area were identified in the 1980s as Martian in origin.

ramyadevims Uploaded by ramyadevims on Jul 17, 2009. FINAL IMPACT - Desktop Nexus Abstract Download free wallpapers and background images: FINAL IMPACT. Desktop Nexus Abstract background ID 133887. 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.
The most significant recorded impact in recent 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 kilometers (3–6 mi) above the Earth's surface, felling an estimated 80 million trees over 2,150 square kilometers (830 sq mi). But 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. 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. Another fireball blew up over the Australian town of Dubbo in April 1993, shaking things up but causing no harm.
A small number of meteorite falls have been observed with automated cameras and recovered following calculation of the impact point. The first of these was the Pribram 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 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. 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 Pribram, led to the discovery and orbit calculations for the Neuschwanstein meteorite in 2002.

The only reported fatality from meteorite impacts is an Egyptian dog who was killed in 1911, although this report is disputed. The meteorites that struck this area were identified in the 1980s as Martian in origin.
Rating: 4.2