Skip to comments.The Hazard of Near-Earth Asteroid Impacts on Earth
Posted on 12/02/2004 10:51:16 AM PST by SunkenCiv
The actual damage that a NEA impact might cause on Earth was concretely described by Baldwin, a leading advocate for the impact origin of lunar craters. Later, Opik... proposed that NEA impacts might account for mass extinctions in the Earth's paleontological record. Around the same time, Shoemaker firmly established the impact origin of Meteor Crater in Arizona... [I]t was not only a cultural but a scientific shock when Mariner 4's first photographs of the Martian surface revealed it to be covered by craters; a decade later, Mariner 10 found the same on Mercury... In 1979 and 1980, the Voyagers first encountered Jupiter and Saturn, demonstrating that cratered surfaces extended from Mercury at least out through the giant planets' satellite systems... Even after discovery of the Chicxulub impact structure in Mexico and its temporal simultaneity with the Cretaceous Tertiary (K T) boundary and mass extinctions, it has taken some earth scientists a while to recognize and accept the statistical inevitability that Earth is struck by asteroids and comets. Each impact, occurring on timescales of tens to hundreds of Myr, liberates tens of millions to billions of megatons (Mt, TNT-equivalent) of energy into the fragile ecosphere, which must have had dramatic consequences every time. A few researchers still consider the Chicxulub impact to be only one of several contributing factors to the K T extinctions... Some geoscientists still think of asteroid impacts as ad hoc explanations for paleontological changes and they resist the logic that earlier, even greater impact catastrophes surely occurred. If the great mass extinctions are not attributed to impacts (e. g., explained instead by episodes of volcanism or sea regressions), one must ask how the huge impacts that must have occurred failed to leave dramatic evidence in the fossil record.
(Excerpt) Read more at boulder.swri.edu ...
FR Lexicon·Posting Guidelines·Excerpt, or Link only?·Ultimate Sidebar Management·Headlines
PDF to HTML translation·Translation page·Wayback Machine·My Links·FreeMail Me
Gods, Graves, Glyphs topic·and group·Books, Magazines, Movies, Music
Please FREEPMAIL me if you want on, off, or alter the "Gods, Graves, Glyphs" PING list --
Archaeology/Anthropology/Ancient Cultures/Artifacts/Antiquities, etc.
The GGG Digest -- Gods, Graves, Glyphs (alpha order)
If the great mass extinctions are not attributed to impacts (e. g., explained instead by episodes of volcanism or sea regressions), one must ask how the huge impacts that must have occurred failed to leave dramatic evidence in the fossil record.I love that particular point. The only answer that satisfies all the available data is, "delusional belief system". :') If experience is any guide, the delusional parade is going to begin, and I won't have to save my spot along the route for very long. :')
It's a small point but isn't a "near Earth impact" actually a "miss" ? And wouldn't the impact from a miss be zero?
Heh... good point... but he refers to impacts by Near-Earth objects.
I read a REALLY BAD sci fi novel about a near impact once. In the novel an asteroid or comet passed close over the north pole. Some strange gravatational effect caused a large part of our atmosphere to be draw up over the north pole in some kind of freak super high pressure system.
Long story short. The atmosphere suddenly snapped back causing thousand+ MPH winds across the planet wiping out mankind.
And because of the cool cover:
You think that's bad?
Some yoyo wrote (and sold) a novel where there is a massive nuclear explosion near Antarctica, and the resulting radioactive water races over the world's oceans at 700 miles per hour...
Yeah I think some sci fi writers are the same people coming up with conspiracy theories for the democrats. A good sci fi writer uses good hard science or at least good theoretical science.
The most risible section of Velikovsky's book was where he admitted his ideas to be incompatible with Newtonian physics: and then recommended that Newtonian physics be reconstructed so as to conform to his theories!
You mean Venus didn't really get ejected from the Great Red Spot on Jupiter?
Sounds like the UN general assembly on a typical day ...
The Chicxulub impact event caused the dinos to go extinct.The Day the World BurnedThe cataclysm went far beyond the regular insults from which living things must recover. The asteroid or comet flashed through the sky more than 40 times as fast as the speed of sound. It was so large that when its leading edge made contact with ground, its trailing edge was at least as high as the cruising altitude of a commercial airliner. It produced an explosion equivalent to 100 trillion tons of TNT, a greater release of energy than any event on our planet in the 65 million years since then... The crater, called Chicxulub after modern Maya villages in the area, is approximately 180 kilometers in diameter and is surrounded by a circular fault 240 kilometers across, apparently produced when the crust reverberated with the shock of the impact...
by David A. Kring
and Daniel D. Durda
November 27, 2003
FR Lexicon:Posting Guidelines:Excerpt, or Link only?:Ultimate Sidebar Management:Headlines
PDF to HTML translation:Translation page:Wayback Machine:My Links:FreeMail Me
Gods, Graves, Glyphs topic:and group:Books, Magazines, Movies, Music
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.