door sen... » di 26 apr 2005, 20:27
Wat voor gevolgend heeft het voor de wereldbevolking als een komeet met een diameter van 1km op de aarde botst?
Op
deze site veel informatie over het in kaart brengen van, en onderzoek naar Near Earth Asteroids en hun impact hazard.
NEAs Smaller than 1 km. While NEAs <1 km diameter probably cannot threaten a global catastrophe, those between 200 m and 1 km in diameter also pose a significant threat. One could cause a tsunami of size and destructive power perhaps unprecedented in historical times, threatening everything near the coast of whatever ocean happens to be struck. Moreover, such objects are much more numerous than the larger ones and hence they strike Earth perhaps tens of times more frequently than the civilization-threatening asteroids. That means that there is a much higher chance (perhaps 1%) that we or our grandchildren will actually have to deal with such a disaster during this century.
While smaller NEAs are being found in great numbers (roughly twice as many have been found as those >1 km diameter), it would be very challenging to undertake a nearly-complete census of them, as is being done for the larger NEAs by Spaceguard. 200 m NEAs are 3 magnitudes fainter than 1 km asteroids. Suitable, dedicated groundbased telescopes (large [roughly 5 m] aperture, sensitive detectors) would have to be constructed in appropriate numbers. A recent recommendation by the American astronomical community (National Research Council 2001) is for construction of a single 8.4 m telescope, the Large-aperture Synoptic Survey Telescope (LSST), which would have as one of its major objectives, cataloging 90% of NEAs > 300 m diameter in one decade. There are difficulties in searching for small asteroids, such as problems with background objects (stars and galaxies) and the night sky background; infrared techniques could address some of the problems. The required astrometric follow-up programs would have to be developed as a separate, professional effort since the vast majority of these NEAs would be beyond the capabilities of the volunteers currently following up brighter discoveries. Physical characterization of small NEAs is, of course, correspondingly more difficult than for the larger ones.
Table 1 describes some of the more common immediate environmental consequences from impacts by NEAs in three size ranges:
"Table 1" vind je onderaan de pagina.
[quote]Wat voor gevolgend heeft het voor de wereldbevolking als een komeet met een diameter van 1km op de aarde botst?[/quote]
Op [url=http://www.boulder.swri.edu/clark/neowp.html]deze site[/url] veel informatie over het in kaart brengen van, en onderzoek naar Near Earth Asteroids en hun impact hazard.
[quote]NEAs Smaller than 1 km. While NEAs <1 km diameter probably cannot threaten a global catastrophe, those between 200 m and 1 km in diameter also pose a significant threat. One could cause a tsunami of size and destructive power perhaps unprecedented in historical times, threatening everything near the coast of whatever ocean happens to be struck. Moreover, such objects are much more numerous than the larger ones and hence they strike Earth perhaps tens of times more frequently than the civilization-threatening asteroids. That means that there is a much higher chance (perhaps 1%) that we or our grandchildren will actually have to deal with such a disaster during this century.[/quote]
[quote]While smaller NEAs are being found in great numbers (roughly twice as many have been found as those >1 km diameter), it would be very challenging to undertake a nearly-complete census of them, as is being done for the larger NEAs by Spaceguard. 200 m NEAs are 3 magnitudes fainter than 1 km asteroids. Suitable, dedicated groundbased telescopes (large [roughly 5 m] aperture, sensitive detectors) would have to be constructed in appropriate numbers. A recent recommendation by the American astronomical community (National Research Council 2001) is for construction of a single 8.4 m telescope, the Large-aperture Synoptic Survey Telescope (LSST), which would have as one of its major objectives, cataloging 90% of NEAs > 300 m diameter in one decade. There are difficulties in searching for small asteroids, such as problems with background objects (stars and galaxies) and the night sky background; infrared techniques could address some of the problems. The required astrometric follow-up programs would have to be developed as a separate, professional effort since the vast majority of these NEAs would be beyond the capabilities of the volunteers currently following up brighter discoveries. Physical characterization of small NEAs is, of course, correspondingly more difficult than for the larger ones.[/quote]
[quote]Table 1 describes some of the more common immediate environmental consequences from impacts by NEAs in three size ranges:[/quote]
"Table 1" vind je onderaan de pagina.
