Talk:Impact event
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Great work on the merge Bryan! --mav
- Thanks. :) Bryan
Note the recently raised possibility that the Permian and Cretaceous impact objects causing extinction events may have been massive molten rocks ejected from the flood basalt events which occurred at the same times rather than asteroid impacts -- Derek Ross
- I'd need some pretty good external references before I'd consider that a plausible theory, personally. Basalt flood eruptions are relatively sedate for their size, not like explosive volcanos. And the impacts proposed for these events are huge; Chicxulub Crater is either 180 or 300 kilometers in diameter (jury's not entirely decided yet) and the Bedout is about 200 kilometers in diameter, both of which suggest impactors about 10 kilometers across. An explosion that would hurl a mass that big out of Earth's atmosphere would be about as energetic as the explosion that would result when it falls back in, and I don't think anyone's ever proposed a volcanic eruption anywhere near that violent. The basaltic flood eruptions were dramatic enough as it is without proposing continent-sized explosions accompanying them. Bryan 07:37, 23 May 2004 (UTC)
There's no doubt that it's speculation at the moment based on computer modelling of the mantle. However the modelling has shown that the titanic explosions required to launch these huge masses are possible under the right circumstances (in the model at least). And there is some physical evidence to follow up. See New Scientist (8-May-2004). I just thought that I should make everyone aware of a possible alternative to the asteroid theory, so that we don't start saying is when we should be saying is thought to be. I'm certainly not saying "Drop the asteroid theory. Here's something better". It's early days yet for the "verneshot" theory and, as you say, it involves a major rethink on flood basalt eruptions. -- Derek Ross 19:17, 23 May 2004 (UTC)
I think this is a great article, and I'd like to see it nominated for feature status. There are however a few things that appear to be in need of elaboration; in particular, there ought to be some more info on the direct consequences of a major collision (some of which is mentioned in e.g. crater but should also be covered here).
Thoughts? Fredrik 12:50, 23 May 2004 (UTC)
I think it would need a better description of the first 4.5 billion years of Earth's history than "The current traditional Biblical view of history held that the Earth was created 6,000~10,000 years ago" Astronaut 19:04, 24 July 2006 (UTC)
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[edit] This is Correct
I would have to say that, scientifically this assumption is correct. And can also be proven.
Ha! You senile liberals on the Wiki are a funny lot.
Partner, this absurd theory was debunked over the past two years. Despite all the lurid magazine covers, it was a rubbish idea and has been abandoned. The dinosaurs were not killed by an asteroid impact. Very theatrical stuff, though - unfortunately not science.
It is also unfortunate that Alvarez and Gould attacked half the scientists in the country who criticized the notion, destroyed their careers and got them dropped from tenure for daring to oppose the screamin' Alvarez brothers. What a shame. (Anonymously contributed by Anonymous User:211.27.137.236 whose contribution can also be enjoyed at Talk:Stephen Jay Gould.)
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. No, this is not a scientific assumption. Even a quick read through Wikipedia entries on Extinction events will correct this impression. I haven't removed this text, however. --Wetman 18:53, 27 Dec 2004 (UTC)
[edit] rate of earth impacts
This information is a bit out of date:
The late Eugene Shoemaker of the US 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.
[re: Tunguska] Shoemaker estimated that one of such magnitude occurs about once every 300 years.
See, for instance, Tunguska-type impacts less common than thought
The quotes below are from _The flux of small near-Earth objects colliding with the Earth_ Brown et al. Nature, Volume 420, Issue 6913, pp. 294-296. (2002)
"The Earth is struck by an object with the energy of Tunguska (assumed to be 10 MT) every 1,000 years."
"We estimate that the Earth is on average struck annually by an object of energy ~5 kton (with a possible range of 2-10 kton), and struck each month by an object with 0.3 kt of energy. Every ten years, an object of energy ~50 kton impacts Earth."
--Mu301 14:43, 2 Jan 2005 (UTC)
[edit] Impact Events in Fiction
I completely re-wrote this section in an effort to make the media references more mainstream and more centered around the books and movies which are specifically about impacts (also more consistent with other Wikipedia articles). One thing which is missing, though; I'm sure there are early sci-fi stories (in Astounding, etc.) about impact events, but I've not been able to find a specific citation. Could someone who collects 30's and 40's science fiction help out with stories of historical note? (i.e. the "first" impact story) Jberkus 18:42, 2 October 2005 (UTC)
[edit] Improvement drive
Asteroid deflection strategies has been nominated on WP:IDRIVE. Support it with your vote if you want it to be improved.--Fenice 22:45, 29 December 2005 (UTC)
[edit] War, near misses, etc.
This makes for a good story, but I doubt it is really true:
- It is very likely that a great many more near misses occur but are never detected. In addition to the danger of a strike, the possibility of war at a time of international tension due to a near miss triggering attack early warning systems, or a strike, is very real.
How would one estimate near misses that are never detected? Seems like a hard problem, and frankly I would be surprised if there are "many" near misses by hazardous asteroids (i.e. >100 m). Also, as there has never been a war by asteroid, and the things have speeds and trajectories much different than missles, I honestly think it unlikely that modern surveillance would have a "very real" risk of mistaking an asteroid for an attack to the point of creating an international incident. Please provide sources for both claims. Dragons flight 16:31, 6 March 2006 (UTC)
[edit] Attention
I have added the attention tag, particularly re the section on mass extinctions, but some concerns are of more general relevance. Most fundamentally, the article needs to directly cite assertions made in the text- including a (small) number of references at the bottom without direct links is not enough. Some of the key points made (ie the discovery of the Chicxulub crater) are at best only partially correct, and a general expansion is very much in order. The selection of material currently seems to be a little bit patchy and incomplete; it is not even approaching a holistic treatment of the subject. The article does currently read a bit like a school essay project (although to be fair I would probably give it a C+, or even a B!). Cheers, Badgerpatrol 16:02, 5 April 2006 (UTC)
- I fixed the majority of what I could based on what I think you meant was wrong with the article. I added some references, cited some, added some footnotes; I don't know if I did everything you wanted so please explain in detail if more is needed! For now, I'm going to remove the "cleanup tag" Kosmkrmr 00:01, 5 March 2007 (UTC)
[edit] point of confusion
The article states, "In the past 600 million years there have been five major mass extinctions that on average extinguished half of all species. The largest mass extinction to have affected life on Earth was in the Permian-Triassic, which ended the Permian period 250 million years ago and killed off 90% of all species. The last such mass extinction led to the demise of the dinosaurs and has been found to have coincided with a large asteroid impact; this is the Cretaceous-Tertiary (K-T) extinction event. There is no solid evidence of impacts leading to the four other major mass extinctions, though a recent report from Ohio State scientists stated that they have located a 483-km diameter impact crater beneath the East Antarctic Ice Sheet which may date back about 250 million years, based on gravity measurements, which might associate it with the Permian-Triassic extinction event."
Back in 2001, the AP reported, "The Permian-Triassic impactor, either an asteroid or comet, left behind subtle deposits of buckminsterfullerenes, or 'Buckyballs,' a form of carbon shaped like a volley ball with a hollow cage-like cavity inside" Recer, 2001). Is this research not yet deemed "solid evidence"? If it were, shouldn't this entry state that there's evidence (in additon to the Antartic crater, of course) that two out of five extinction events were caused by a large asteroid or comet?
[edit] List of doomsday scenarios
Could use votes to save this article, thanks MapleTree 22:29, 28 September 2006 (UTC)
[edit] external links
Hi. What about this site I found, which has an asteroid impact simulator, and other simulators. I know it seems a bit immature with all the "marvin the martian" stuff. Otherwise, dispite its innacuracies, it still is the only site I found providing simulations on impacts elsewhere in the solar system. It also has simulators about orbits and stars and such. Should this and other links be included? I don't think it would be spam. Thanks. AstroHurricane001(Talk+Contribs+Ubx) 20:43, 3 March 2007 (UTC)
