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... Science Frontiers ONLINE No. 49: Jan-Feb 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Geomagnetic Reversals From Impacts On The Earth R.A . Muller and D.E . Morris review the evidence tying geomagnetic reversals to the impacts of large bodies with the earth: the tektites and microtektites; the climate changes; the biological extinctions, etc. Then they propose a physical mechanism for geomagnetic reversals: "The impact of a large extraterrestrial object on the Earth can produce a geomagnetic reversal through the following mechanism: dust from the impact crater and soot from fires trigger a climate change and the beginning of a little ice age. The redistribution of water near the equator to ice at high latitudes alters the rotation rate of the crust ... Science Frontiers ONLINE No. 49: Jan-Feb 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Geomagnetic Reversals From Impacts On The Earth R.A . Muller and D.E . Morris review the evidence tying geomagnetic reversals to the impacts of large bodies with the earth: the tektites and microtektites; the climate changes; the biological extinctions, etc. Then they propose a physical mechanism for geomagnetic reversals: "The impact of a large extraterrestrial object on the Earth can produce a geomagnetic reversal through the following mechanism: dust from the impact crater and soot from fires trigger a climate change and the beginning of a little ice age. The redistribution of water near the equator to ice at high latitudes alters the rotation rate of the crust ...
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... Science Frontiers ONLINE No. 85: Jan-Feb 1993 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Heavy traffic in near-earth space That region of outer space near the earth carries a heavier load of flotsam and jetsam than scientists expected. The devastation of the 1908 Tunguska impact in Siberia warns us that this space debris -- meteors, comets, asteroids -- is an active threat. A recent spate of articles paints an ominous future. The earth's retinue of mini-asteroids. "Asteroids as big as houses pass near the Earth 100 times more often than anyone suspected. On an average day, about 50 asteroids measuring at least 10 metres across come closer to the Earth than the Moon, and each year about ... such objects may hit the planet." (Second reference below.) These startling data come from D. Rabinowitz and coworkers at the University of Arizona, who have been scanning nearby space with a telescope fitted with supersensitive charge-coupled devices (CCDs). They have picked up astronomical objects that have escaped conventional instruments. Several sources have been suggested for this unexpected, threateningly large population of small asteroids: (1 ) debris hurled earthward from collisions within the asteroid belt located between Mars and Jupiter; (2 ) the breakup of a large object formerly in orbit about the earth; and (3 ) fragments blasted off the moon by impacts of large asteroids there. (Kerr, Richard A.; "Earth Gains a Retinue of Mini-Asteroids," Science, 258: ...
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... Science Frontiers ONLINE No. 110: Mar-Apr 1997 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects A METEOR IMPACT OR EARTH SLUMP?November 22, 1996. The Honduras-Guate mala border. About 10:10 PM, the residents of this area observed a red-andyellow fireball moving east-to-west. The bolide's passing was marked by a loud detonation. From this information, one would bet heavily that this was simply a routine meteor detonation caused by the heat generated during entry into the atmosphere. The next morning, however, people discovered a landslide covering several acres on the slopes of Cerro Negro, a mountain 14 kilometers from San Luis. Did the meteor slam into the mountain overnight? So far ... Science Frontiers ONLINE No. 110: Mar-Apr 1997 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects A METEOR IMPACT OR EARTH SLUMP?November 22, 1996. The Honduras-Guate mala border. About 10:10 PM, the residents of this area observed a red-andyellow fireball moving east-to-west. The bolide's passing was marked by a loud detonation. From this information, one would bet heavily that this was simply a routine meteor detonation caused by the heat generated during entry into the atmosphere. The next morning, however, people discovered a landslide covering several acres on the slopes of Cerro Negro, a mountain 14 kilometers from San Luis. Did the meteor slam into the mountain overnight? So far ...
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... The back side of the comet and most of the separated particles are much lower in temperature than the impacting side, and in an impact of a smaller comet (which would look much the same), organic material at the rear of the comet would survive intact. Figure provided by Paul Thomas. "New simulations suggest that large amounts of the organic molecules needed to form the first life on Earth could have been brought by comets that bombarded the planet early in its history. The models show that comets of moderate size would have slowed down enough during entry into the Earth's atmosphere for their organic component to survive the impact intact. .. .. . "The idea that comets supplied the Earth with the organic material needed to create life has been around for more than 20 ... Science Frontiers ONLINE No. 63: May-Jun 1989 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Comets And Life A comet impact: Cross-sectional view 0.637s after impact of a comet into a 3km-deep ocean (light dots) underlain by basaltic crust (darker grid) in the smoothed particle hydrodynamic model of Thomas et al. Small vertical ticks are 1 km apart, small horizontal ticks 1.25 km apart. The comet in this figure has a radius of 1 kilometer and an impact velocity of 15 km/s and is shown by dark dots in the ocean. The initial spherical comet has become flattened, and parts of it have separated from the main body. The back side of the comet and ...
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... " is a term now in vogue. And, believe it or not, the rains of tektites discussed below may have been the forerunners of climatic catastrophes similar to the postulated nuclear winters. We shall call them "meteor-impact winters. First, a tad of background: Great meteor impacts and tektite events seem to have occurred nearly simultaneously with deep-cutting biological extinctions and reversals of the earth's magnetic field. Ever since this apparent synchrony was recognized a few decades ago, theorists have been vying in generating scientific scenarios, especially some mechanism that would reverse the earth's magnetic field. New entrants in the lists are R. Muller and D. Morris, two Berkeley physicists. Here is how they see it: "A sufficiently large asteroid or cometary nucleus hitting the ... Science Frontiers ONLINE No. 53: Sep-Oct 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Meteor-impact winters, magnetic field reversals and tektites "Nuclear winter" is a term now in vogue. And, believe it or not, the rains of tektites discussed below may have been the forerunners of climatic catastrophes similar to the postulated nuclear winters. We shall call them "meteor-impact winters. First, a tad of background: Great meteor impacts and tektite events seem to have occurred nearly simultaneously with deep-cutting biological extinctions and reversals of the earth's magnetic field. Ever since this apparent synchrony was recognized a few decades ago, theorists have been vying in generating scientific scenarios, especially some mechanism that would reverse ...
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... More confusion at the k-t boundary Just a few years ago, many scientists, especially physicists and astronomers, considered the Book of Science to be closed in the matter of what happened at the Cretaceous-Tertiary (K -T ) boundary, 65 million years ago, and why the dinosaurs met their end. It was declared, rather imperiously, that a large asteroid had impacted the earth, causing much physical and biological devastation. Many scientific papers are still being written on this singular period in the earth's history, and the situation is no longer so clear-cut. We select for brief review four papers, each with a different perspective. Occurrence of stishovite. Stishovite, a dense phase of silica, is widely accepted as an indicator of terrestrial impact events. ... Sourcebook Subjects More confusion at the k-t boundary Just a few years ago, many scientists, especially physicists and astronomers, considered the Book of Science to be closed in the matter of what happened at the Cretaceous-Tertiary (K -T ) boundary, 65 million years ago, and why the dinosaurs met their end. It was declared, rather imperiously, that a large asteroid had impacted the earth, causing much physical and biological devastation. Many scientific papers are still being written on this singular period in the earth's history, and the situation is no longer so clear-cut. We select for brief review four papers, each with a different perspective. Occurrence of stishovite. Stishovite, a dense phase of silica, is widely accepted as an indicator of terrestrial impact ...
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... Science Frontiers ONLINE No. 36: Nov-Dec 1984 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The Case Against Impact Extinctions The neocatastrophists seem to be getting overly smug with their iridium-rich deposits at the Cretaceous-Tertiary boundary. Is there really incontrovertible evidence that a large asteroid or comet hit the earth at this point in history, causing widespread biological extinctions? To add some perspective, Leigh M. Van Valen has tossed 15 arguments against impact extinctions on the scales. Ten of these are reproduced below, as taken from Nature. More de-tails may be found in Paleobiology, 10: 121, 1984. Freshwater life was unaffected; In Montana and its vicinity, the last occurrence of dinosaurs was detectably below the crucial ... Science Frontiers ONLINE No. 36: Nov-Dec 1984 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The Case Against Impact Extinctions The neocatastrophists seem to be getting overly smug with their iridium-rich deposits at the Cretaceous-Tertiary boundary. Is there really incontrovertible evidence that a large asteroid or comet hit the earth at this point in history, causing widespread biological extinctions? To add some perspective, Leigh M. Van Valen has tossed 15 arguments against impact extinctions on the scales. Ten of these are reproduced below, as taken from Nature. More de-tails may be found in Paleobiology, 10: 121, 1984. Freshwater life was unaffected; In Montana and its vicinity, the last occurrence of dinosaurs was detectably below the crucial ...
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... Science Frontiers ONLINE No. 42: Nov-Dec 1985 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Origin Of The Moon Debated In October of 1984, the Conference on the Origin of the Moon convenved in Kona, HI. The clear favorite among the four contending hypotheses was the earth-impact scenario, which may be stated as follows: "Near the end of the Earth's accretion, after its core had formed and while the growing planet was still molten, an object at least the size of Mars smashed into it at an oblique angle. The cataclysm put large quantities of vaporized or partially vaporized impactor and Earth into orbit. The primitive Moon formed from that material." Conferees turned thumbs down on the theory that the ... was captured by the earth. Still not ruled out are the double-planet hypothesis (earth and moon accreted in their present configuration) and the fission-from-earth theory. (Taylor, G. Jeffrey; "Lunar Origin Meeting Favors Impact Theory," Geotimes, 30:16, April 1985.) Reference. See SF#37 for more details on all four theories mentioned above. From Science Frontiers #42, NOV-DEC 1985 . 1985-2000 William R. Corliss ...
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... Coming Revolution In Planetology "Current ideas about the moon appear to be mistaken on two fundamental points. First, at least within certain large classes of lunar craters, internal origin (i .e ., some form of volcanism) predominates over impact; this result raises questions about the reality of the 'era of violent bombardment.'Second, the origin of tektites by meteoric impact on the earth cannot be reconciled with physical principles and is to be abandoned. The only viable alternative is origin by lunar volcanism, which implies the following: continuance of (rare) explosive lunar volcanism to the present time; existence of silicic lunar volcanism and of small patches of silicic rock at the lunar surface; a body of rock in the lunar interior, probably at great depth, which is closely ... Science Frontiers ONLINE No. 39: May-Jun 1985 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The Coming Revolution In Planetology "Current ideas about the moon appear to be mistaken on two fundamental points. First, at least within certain large classes of lunar craters, internal origin (i .e ., some form of volcanism) predominates over impact; this result raises questions about the reality of the 'era of violent bombardment.'Second, the origin of tektites by meteoric impact on the earth cannot be reconciled with physical principles and is to be abandoned. The only viable alternative is origin by lunar volcanism, which implies the following: continuance of (rare) explosive lunar volcanism to the present time; existence of silicic lunar volcanism ...
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... grains of shocked quartz. The other two could be volcanic say the skeptics. It will take an expedition to Chad to clarify things. (Kerr, Richard A.; "Impact Craters All in a Row?" Science, 272:33, 1996) A final comment -- at last! All impactcrater chains are relevant to the claim of H.R . Shaw that even the earth's largest impact structures are found in swathes (chains). In his wonderfully heretical book Craters, Cosmos, and Chronicles: A New Theory of the Earth, Shaw mentions several such swathes. One of his chains includes Chicxulub (beneath Yucatan), Manson (Iowa), Avak (Alaska), and three more in Russia. These are giant craters stretched out over much of ... Science Frontiers ONLINE No. 106: Jul-Aug 1996 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Impact craters: the party line revised and re-revised 100 years ago. Back in 1900, a geologist risked his reputation by suggesting that Arizona's Meteor Crater was an impact structure. It had to be volcanic or perhaps due to a steam explosion! 50 years ago. In 1950, a geologist risked his reputation by suggesting that large impact structures existed; that is, bigger than 10 kilometers in diameter. 0 years ago. Today, geologists converse blithely about 100-kilometer structures buried beneath the Yucatan and Chesapeake Bay. They are, however, exceedingly chary about long chains of impact structures. Those eight craters in a ...
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... Science Frontiers ONLINE No. 53: Sep-Oct 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Tektite-like objects at lonar crater, india Arguments about the origin of tektites persist in the scientific literature. A strong consensus has these small, drop like glassy bodies originating when meteors smash into the earth, liquifying themselves and some of the surface rocks. The resulting liquid droplets solidify in flight and when they descend form "strewn fields" hundreds, even thousands, of miles in extent. The main argument has been over whether the actual impact craters giving rise to the tektites might actually be on the moon instead of the earth. Looking over the literature, one sees that this debate has been characterized by much invective and scientific infighting ... Today, most scientists concur that some tektite strewn fields are definitely associated with specific, although distant, meteor craters on the earth's surface. Unfortunately, the large separations of craters and strewn fields add a circumstantial flavor to the evidence. However, some tektite-like objects are to be found in the immediate vicinities of terrestrial craters, but not in far-flung strewn fields; viz., the Aouelloul Crater in Mauritania, and the Zhamashin Crater in the USSR. Another example has now come to light: the Lonar Lake Crater, a 50,000-year-old impact crater, in the Deccan flood basalts in India. From the paper's abstract: "Homogenous, dense glass bodies (both irregular and splash form) with high silica contents ( 67% ...
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... No. 98: Mar-Apr 1995 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects A Unified Theory Of Geophysics It takes a lot of nerve to propose a theory that can unite such a fragmented field as geophysics. H.R . Shaw makes a try in his new book: Craters, Cosmos, and Chronicles: A New Theory of the Earth . Shaw's ideas have recently been reviewed in Science News and our item is based on that article. Shaw contends that cosmic projectiles -- asteroids and comets -- have controlled almost all features of the earth's evolution. For example: Impacts have determined the positions of the continents. They have controlled the geomagnetic field. They have created volcanoes and massive basalt flows. They ... caused mass extinctions. Of course, for two centuries, other catastrophists have proposed similar dire consequences of giant impacts. But Shaw does introduce three ideas that are worth recording here. Large impact craters occur in swaths. Although this has been suggested before, Shaw has mapped out several swaths where large craters of about the same age are located. His "K -T swath" includes the Chicxulub crater (Yucatan), the Manson crater (Iowa), the Avak crater (Alaska), and three more in Russia -- all of which were gouged out about the time of the Cretaceous-Tertiary (K -T ) boundary. Shaw has plotted several other swaths of different ages. The application of chaos theory to solar system debris. Shaw hypothesizes that nonlinear gravitational effects channel asteroids ...
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... the spike no longer seems so sharp. In fact, it is spread through about 3 meters of sediments at the boundary. Said sediments apparently took 500,000 years to accumulate! This broad smear of iridium no longer seems indicative of a single extraterrestrial impact. (Rocchia, R., et al; "The CretaceousTertiary Boundary at Gubbio Revisited: Vertical Extent of the Ir Anomaly," Earth and Planetary Science Letters , 99:206, 1990.) Comment. Is it even indicative of multiple impacts? Recall that no one has yet (1990) found a single crater that everyone will accept as evidence. Reference. Iridium spikes and the supposed Cretaceous-Tertiary impact are to be found in ESB1 in our catalog: Anomalies in Geology. For more on this volume, see ... Science Frontiers ONLINE No. 73: Jan-Feb 1991 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Asteroid impact or volcanos?The debate over the real cause of the terrestrial catastrophism that occurred at the Cretaceous-Tertiary boundary, some 65 million years ago, grinds on. Some physical scientists claim rather imperiously that the dinosaurs and many other species were done in by the impact of a huge asteroid/meteorite. The worldwide iridium spike is conclusive, they say. Many paleontologists and geologists, however, remain unconvinced and prefer widespread volcanism. We have already covered the various arguments in past issues of Science Frontiers; here, we want to advise our readers that a pair of excellent articles by principals in this debate have appeared in Scientific American ...
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... Sourcebook Subjects The Stealth Catastrophe Recently, as geologists reckon time -- only 800,000 years ago -- Australia, Southeast Asia, and the eastern Indian Ocean were bombarded by untold numbers of small, oddly shaped stones called "tektites." New finds of tektites have expanded the strewn field of these Australasian tektites to include part of China. It now appears that about 30% of the earth's area was subjected to this stony bombardment. It is inescapable that the Australasian-tektite fall was a major event in the earth's history. But where are other signs of this great catastrophe? The present consensus holds that the Australasian tektites originated when a large celestial body slammed into our planet somewhere in Southeast Asia. The energy of the impact splashed droplets of molten rock into ... atmosphere, where they were shaped aerodynamically and then fell as tektites. The extent of the immense Australasian-tektite strewn field implies a hard-to-miss crater about 100 kilometers in diameter. Yet, despite the geological recency of the event and despite much geological surveying, no convincing crater has been discovered. (SF#115) So, we have abundant evidence of a terrestrial event encompassing much of the planet but no "smoking crater"! The mystery deepens when one realizes that whatever cataclysm sent the Australian tektites aloft may have been comparable in magnitude to the impact that extinguished the dinosaurs (and other fauna) some 65 million years ago. This much older event has its craterburied below the Yucatan and is further marked by widespread biological extinctions. In contrast, the Australasian-tektite ...
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... some 2-3 .5 billion years ago these plains were covered with oceans. These ancient seas, perhaps as much as 700 meters deep, protected the plains from direct impacts. Further, crater density counts for Chryse and the Martian highlands imply that Mars possessed a fairly dense atmosphere until about 1.5 billion years ago. In his Abstract Helfer speculates as follows: "With both early Earth and early Mars having similar atmospheric compositions and not too dissimilar atmospheric structures, it is reasonable to suppose that the warm Martian oceans, like the ancient oceans of Earth, would develop anerobic and aerobic photosynthesizing prokaryotes and structures like stromatolites. Their development might have changed the Martian atmosphere. Their fossils might be found along the fringes of the old oceans, the northern lowland plains." (Helfer ... Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Gaia on mars?H.L . Helfer, University of Rochester, noting the absence of extensive cratering on the northern plains of Mars, suggests that some 2-3 .5 billion years ago these plains were covered with oceans. These ancient seas, perhaps as much as 700 meters deep, protected the plains from direct impacts. Further, crater density counts for Chryse and the Martian highlands imply that Mars possessed a fairly dense atmosphere until about 1.5 billion years ago. In his Abstract Helfer speculates as follows: "With both early Earth and early Mars having similar atmospheric compositions and not too dissimilar atmospheric structures, it is reasonable to suppose that the warm Martian oceans, like the ancient oceans of Earth, ...
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... Science Frontiers ONLINE No. 58: Jul-Aug 1988 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Is the earth seeding the rest of the solar system?We begin with the lead paragraph from a recent letter to Nature from H.J . Melosh; "Recent evidence that the SNC meteorites originated on Mars raises the question of whether large impacts on Earth may eject rocks that could fall on Mars (or other planets in the Solar System) and, if so whether they might contain spores or some sort of viable microorganisms that would have the opportunity to colonize Mars." After some computations Melosh concludes: "It seems likely that the impacts that produced craters on Earth that are greater than 100 km in diameter would each have ejected ... of tons of near-surface rocks carrying viable microorganisms into interplanetary space, much in the form of boulders large enough to shield those organisms from ultraviolet radiation, low-energy cosmic rays, and even galactic cosmic rays. Under such circumstances spores might remain viable for long periods of time." (Melosh, H.J .; "The Rocky Road to Panspermia," Nature, 332:687, 1988.) Comment. Next we need a reasonable mechanism that spreads life through interstellar space. Light pressure, that's it; and the idea is over a century old! Incidentally, SNC is short for Shergottites, Nakhalites, Chassignites; all rare classes of meteorites. From Science Frontiers #58, JUL-AUG 1988 . 1988-2000 William R. Corliss ...
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... Science Frontiers ONLINE No. 68: Mar-Apr 1990 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Impact Delivery Of Early Oceans Where did the earth's oceans come from? For decades the stock answer has been: from the condensation of vapors escaping from the planet's cooling crust; that is, "outgassing." The possibility that some terrestrial water might have ar rived from extraterrestrial sources after the earth's formation has been discounted. The major reason behind this neglect was the expectation that the erosive effects of large-scale impacts of water-carrying comets and asteroids would preclude any net accumulation of volatiles, and could even reduce any existing inventories of surface water. C.F . Chyba has recently reexamined this question ... Science Frontiers ONLINE No. 68: Mar-Apr 1990 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Impact Delivery Of Early Oceans Where did the earth's oceans come from? For decades the stock answer has been: from the condensation of vapors escaping from the planet's cooling crust; that is, "outgassing." The possibility that some terrestrial water might have ar rived from extraterrestrial sources after the earth's formation has been discounted. The major reason behind this neglect was the expectation that the erosive effects of large-scale impacts of water-carrying comets and asteroids would preclude any net accumulation of volatiles, and could even reduce any existing inventories of surface water. C.F . Chyba has recently reexamined this question ...
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... Science Frontiers ONLINE No. 52: Jul-Aug 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Small Icy Comets And Cosmic Gaia L.A . Frank and his associates at the University of Iowa have speculated that the earth is continuously and copiously bombarded by small, icy comets. Not just a few now and then, but a steady rain so intense that over geological time some major geological consequences must ensue. (See SF#44.) Some observers commented that surely these scientists have thrown away their careers by suggesting something so ridiculous. But the data are there -- in the form of dark spots on satellite images of the earth's dayglow -- and late results continue to support this far-out interpretation, ... estimated at about 108 gm each, and the total flux is about 107 small comets per year. If this flux is representative of the average flux over geologic time, then the water influx is sufficient to fill the Earth's oceans. The fluxes of these objects are also large for all the planets outside the orbit of Earth. Considerations of thermal stability imply that the fluxes of comets that impact Venus are considerably less. The outer giant planets may be significantly heated relative to solar insolation by the small-comet impacts. For example, the total energy input due both to solar insolation and comet impacts may be similar for Uranus and Neptune. Thus it is possible that the temperatures of these two planets are similar, even though Neptune is farther from the Sun." (Frank, ...
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... be exogenous; that is, derived from extraterrestrial materials. Once again, comets seem to be the culprits. C.F . Chyba has examined the lunar impact record and derived an estimate of the total mass of objects impacting the moon during the (hypothetical) period of heavy bombardment 3.8 to 4.5 billion years ago. This allowed him to calculate the mass influx for the earth during this period. His conclusion: if only about 10% of the incoming mass consisted of comets (mostly ice), the earth would have acquired all its ocean water. (Chyba, Christopher F.; "The Cometary Contribution to the Oceans of Primitive Earth," Nature, 330:632, 1987.) Comment. Frank claims that the earth today is continually bombarded by ... No. 56: Mar-Apr 1988 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Oceans From Space In keeping with the foregoing extraterrestrial flavor, we are happy to report that our oceans may be exogenous; that is, derived from extraterrestrial materials. Once again, comets seem to be the culprits. C.F . Chyba has examined the lunar impact record and derived an estimate of the total mass of objects impacting the moon during the (hypothetical) period of heavy bombardment 3.8 to 4.5 billion years ago. This allowed him to calculate the mass influx for the earth during this period. His conclusion: if only about 10% of the incoming mass consisted of comets (mostly ice), the earth would have acquired ...
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... Science Frontiers ONLINE No. 47: Sep-Oct 1986 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Oceans from outer space?Back in SF#44, we related how L.A . Frank, at the University of Iowa, had detected dark spots on satellite images of the earth's dayglow. Frank thought that the spots might be due to clouds of water vapor released as small, icy comets hit the atmosphere. P. Huyghe has recently written more about Frank's discovery, his theory, and its reception by the scientific community. "These comets are not occasional visitors, he [Frank] says, like the one that comes by every 76 years and -- lucky for us -- never actually drops ... . No, these are very small, cometlike objects that enter our atmosphere at a rate of 20 per minute, he says. These comets, which he believes must contain about 100 tons of water apiece, vaporize on impact with the atmosphere and fall as rain or snow. Now that may seem like one sizeable cold shower, but on a yearly basis he says it's actually only a tiny fraction of the annual preciptation. Then again, over a span of 4.5 billion years, which is about how old the earth is, that's enough water, he says -- trumpets blaring -- to create the oceans." Naturally, such a theory is very disturbing because it runs counter to the widely accepted idea that the oceans were created by the outgassing ...
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... the antipodal point. It drives the compressed mag netic field into the surface, permanently magnetizing the rocks at the antipodal point. Voila! Magcons. (Hood, L.L ., and Huang, Z.; "Formation of Magnetic Anomalies Antipodal to Lunar Impact Basins: Two-Dimensional Model Calculations," Journal of Geophysical Research, 96:9837, 1991.) Comment. The earth also sports scars from the impacts of large meteoroids. Are there magnetic anomalies opposite these craters? Even more interesting to check out would be the holes blasted in the earth's biosphere by the converging masses of hot gases at the an tipodal points. Wouldn't there be extinctions seen in the fossil record at these antipodal points? Reference. Magcons are cataloged as ALZ1 in The Moon ... Science Frontiers ONLINE No. 78: Nov-Dec 1991 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Meteoroid impacts: the other side of the story Astronomers have long puzzled over the origin of localized magnetic anomalies on the moon. These magnetic concentrations (called "magcons") are located precisely on the opposite side of the moon from the larger lunar basins. How could an impact on the moon magnetize the antipodal region? The impact of a large silicate meteoroid at speeds of 10 kilometers/second would not only blast out a big crater but it would also create a huge cloud of hot, partially ionized gas. This hot gas or plasma will conduct electricity and interact with lunar magnetic fields. As the plasma cloud spreads away from the ...
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... Crater in Arizona, just might be of meteoric origin; then, more and bigger craters (astroblemes) were recognized; and, recently, the discovery of the iridium-rich layer at the Cretaceious-Tertiary boundary has made the subject very popular, as evidenced by the following three items: A long, very thorough and scientific review of geological and biological changes caused by meteor strikes throughout the earth's history. (McLaren, Digby J.; "Bolides and Biostratigraphy," Geological Society of America, Bulletin, 94:313, 1983.) A shorter, popular version of the above. (McLaren, Digby; "Impacts That Changed the Course of Evolution," New Scientist, 100:588, 1983.) Evidence is growing that the collision of planetary material ... the Earth can profoundly affect local geology, and that impacts of very large meteorites may have influenced the evolution of the Earth and the life that exists upon it. This quotation is from the lead-in to the article references below, which also has a nice world map of major impact sites over 1 km in diameter. (Grieve, Richard; "Impact Craters Shape Planet Surfaces," New Scientist, 100:516, 1983.) Reference. Terrestrial cratering phenomena are cataloged in Chapter ETC in Carolina Bays, Mima Mounds. For details about this book, go to: here . From Science Frontiers #31, JAN-FEB 1984 . 1984-2000 William R. Corliss ...
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... . One might say that planetary scientists have just about thrown in the towel on the three major theories of lunar origin. Two recent articles attest to this discouraging situation. A Sky and Telescope article provides an excellent review of all three theories, indicating the reasons why each fails to convince a majority of scientists. The theories and the primary reasons for their rejection are: (1 ) Fission from earth . Lack of sufficient angular momentum in the earthmoon system and the fact that the moon does not orbit in the plane of the earth's equator. (2 ) Gravitational capture . The capture of such a large object in a nearly circular orbit is considered too improbable. (3 ) Earth-moon accretion as a double planet . The compositions of the earth and moon are too different ... we might call the Big Splash Theory. The idea is that a Mars-sized object (1 /10 the earth's mass) made a grazing collision with the earth when the solar system was more heavily populated with debris. This collision vaporized the projectile's rocky mantle as well as a similar quantity from the earth. This material was flung into orbit by the force of the impact and the expanding hot gases. Beyond the Roche Limit, the expelled debris coalesced into the moon. This fourth theory is now seriously considered by planetary scientists who -- so far -- have found no serious defects. (Kerr, Richard A.; "Making the Moon from a Big Splash," Science, 226:1060, 1984.) From Science Frontiers #37, ...
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... Science Frontiers ONLINE No. 107: Sep-Oct 1996 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects "NOT WITH A BANG BUT A WHIMPER"Poet T.S . Eliot speculated that life on earth might not after all be terminated catastrophically, as in the impact of a large asteroid (today's popular doomsday machine). Rather, we might depart slowly, quietly, and mournfully. Of course, Eliot was not thinking of asteroids -- no one foresaw impact havoc in his day. But, his use of the word "whimper" can be attached to another, much slower astronomical agent of planetary death: cosmic dust and gas. Here's the current situation: "For the most part of the past ... million years, the Solar System has been moving through a rather empty region of interstellar space between the spiral arms of the Milky Way. But a few thousand years ago, it entered a diffuse shell of material expanding outward from an active star-forming region called the Scorpius-Centaurus Association. Such 'super-bubble' shells of gas and dust result from the formation of massive stars, or the explosion of those stars as they become supernovas, and contain gas and dust clouds of varying densities." The density of matter in this solarsystem-engulfing shell could well shroud our planetary system with dust and gas a million times more dense than that we now encounter. If this happens, the sun's rays would slowly dim and life forms dependent on photosynthesis would expire. P ...
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... Science Frontiers ONLINE No. 23: Sep-Oct 1982 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The cretaceous-tertiary extinction bolide The recently discovered worldwide iridium-rich layer is taken by many scientists as evidence of the collision of an asteroid or comet with the earth about 65 million years ago. This cataclysmic event is also blamed (by some, at least) for the apparent sudden biological extinctions recorded on these pages of the fossil record. In this setting, the authors of this paper calculate the effects on the earth of a 10-kilometer-diameter object impacting at about 20/km/sec. Do the theoretical results jibe with the geological and paleontological data? Very definitely. Crater ejecta rich in extraterrestrial material would be ... to an altitude of 10 km, where winds would insure global distribution. In terms of biological stress, the 10-km projectile would transfer 40-50% of its kinetic energy to the atmosphere, creating a heat pulse that could raise global temperatures 30 C (50 F) for several days. Many large animals might well succumb to such a temperature transient. In addition, the protective ozone layer might be blown away by shock waves and not reform for a decade. (O 'Keefe, John D., and Ahrens, Thomas J.; "Impact Mechanics of the Cretaceous-Tertiary Extinction Bolide," Nature, 298,123, 1982.) Reference. We catalog biological extinctions at ESB1 in Anomalies in Geology. To order this book, visit: here . ...
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... Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Life Currents In Space A few of the hundreds of meteorites picked up in the Antarctic wastes have chemical properties consistent with a Martian origin. Calculations, too, support the notion that a large meteoric impact could propel bits of the Martian surface into space where, statistically speaking, a tiny fraction would be captured by the earth's gravitational field. Some of these would fall to earth; others would remain in orbit. Now, the reverse scenario has been investigated numerically. S.A . Phinney and colleagues at the University of Arizona have calculated what would happen to small chunks of the earth's crust if a large meteor impact excavated a 60milewide crater. "Phinney's group used a computer to ... Science Frontiers ONLINE No. 63: May-Jun 1989 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Life Currents In Space A few of the hundreds of meteorites picked up in the Antarctic wastes have chemical properties consistent with a Martian origin. Calculations, too, support the notion that a large meteoric impact could propel bits of the Martian surface into space where, statistically speaking, a tiny fraction would be captured by the earth's gravitational field. Some of these would fall to earth; others would remain in orbit. Now, the reverse scenario has been investigated numerically. S.A . Phinney and colleagues at the University of Arizona have calculated what would happen to small chunks of the earth's crust if a large meteor impact ...
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... Science Frontiers ONLINE No. 123: May-Jun 1999 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Moonstone In Orbit?A chunk of "something" about 50 meters across plays tag with the earth as it circles the sun. Discovered February 10, 1999 by an automated, asteroid-hunting telescope in New Mexico, the object's official name is 1999 CG9. Its orbit is nearly circular and 9 million kilometers farther away from the sun than the earth. Its year is 1.09 earth years. "The object's orbit is extremely unusual. Comets and asteroids that cross the earth's orbit normally have eccentric orbits. There is only one asteroid-like object, called 1991 VG, that has an similar ... to that of earth. When it was discovered eight years ago, astronomers thought it might be a spacecraft that had escaped the earth's gravity." However, newly discovered 1999 CG9 is much too large to be a wayward piece of space hardware. The best guess is that it is a piece of the moon that was knocked off by an impacting asteroid. (Hecht, Jeff; "Chip off the Moon," New Scientist, p. 13, February 27, 1999.) Comment. Might it not be a chip off the earth itself? Or perhaps space hardware from somewhere else?! From Science Frontiers #123, MAY-JUN 1999 . 1999-2000 William R. Corliss ...
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... " Who is speaking within the single quotes above? S.J . Gould, a proponent of the punctuated equilibrium view of the evolutionary scenario. He added: "' The history of life is enormously more quirky than we imagined.'" In fact, the geological record shows so many quirk-inducing impacts that there is little room left for slow, plodding, uniformitarian evolution of the earth itself, life-in-general, and humanity. Mammals, for example, may not have survived the postulated (but now assumed factual) Cretaceous-Tertiary impact event simply because they were small in size - not smarter. (Kerr, Richard A.; "Huge Impact is Favored K-T Boundary Killer," Science, 242:865, 1988.) Comment. ... Science Frontiers ONLINE No. 61: Jan-Feb 1989 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Celestial Crucible "Catastrophic extinctions caused by impacts would change the rules governing who is most fit, who becomes extinct, and who survives. 'If much of the patterning of life's history is not set by Darwin's slow biotic mechanisms, then I think Darwin is in trouble. Is catastrophic mass extinction a major agent of patterning?' If so, 'impacts are a quirky aspect' of the process." Who is speaking within the single quotes above? S.J . Gould, a proponent of the punctuated equilibrium view of the evolutionary scenario. He added: "' The history of life is enormously more ...
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... Science Frontiers ONLINE No. 48: Nov-Dec 1986 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Geophysiology The concept of the earth-as-an-organism -- the so-called Gaia hypothesis -- keeps popping up. We now have an excellent progress report on current Gaia research; e.g ., the Daisyworld model; by J.E . Lovelock. He defines Gaia in an early paragraph: "In the early 1970s, Lynn Margulis and I introduced the Gaia hypothesis. It postulated the earth to be a self-regulating system comprising the biota and their environment, with the capacity to maintain the climate and the chemical composition at a steady state favorable for life." L. Margulis is an author ... if Gaia as a closed terrestrial system (see diagram), is not too limited. If Hoyle and Wickramasinghe are correct, the diagram should have a box labelled "outer space," with an inwardly directed arrow carrying life-forms (Hoyle's space viruses and bacteria), meteorites, icy comets, etc. Likewise, the earth can contribute life-forms to the cosmos via impact and volcanic ejecta. Where does geocorrosion fit in? Life-as-a -whole could control terrestrial magnetic field reversals geochemically. This sounds more and more like science fiction, but life-as-a -whole must "want" to evolve to make itself more adaptable and capable of controlling and exploring the cosmos. (These are anthropomorphic desires we assign to life-as- ...
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... impact on the moon that gouged out the crater named Giordano Bruno, 20 kilometers in diameter. June 30, 1908. Siberia. "On the morning of June 30, 1908, a tremendous explosion deep in the Siberian taiga near the Tunguska river caused trees over an area of 40 km in diameter to be flattened in a radial pattern and produced a pressure wave in the atmosphere which circled the Earth." June 17-27, 1975. On the moon. ". .. an unusual meteoroid 'storm' was detected by the array of seismometers placed on the moon during the Apollo missions. The peak impact rate on the moon of 0.5 -to-50-kg objects was about 10 times the normal background during this interval. Such a high rate was not ... Hartung to warn us that June is a dangerous month for earthlings. June 18, 1178. On the moon. ". .. just after sunset, it was reported by at least five men that the 'upper horn of a new moon split and from the division point fire, hot coals, and sparks spewed out.'" These observations have been interpreted as eyewitness accounts of the impact on the moon that gouged out the crater named Giordano Bruno, 20 kilometers in diameter. June 30, 1908. Siberia. "On the morning of June 30, 1908, a tremendous explosion deep in the Siberian taiga near the Tunguska river caused trees over an area of 40 km in diameter to be flattened in a radial pattern and produced a pressure wave in the atmosphere which circled the ...
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... droplets, buttons, even dumbbells. By general agreement, tekites are attributed to meteoric or cometary impacts that melt terrestrial rocks and splash liquid droplets into the atmosphere. There they are shaped by aerodynamic forces and solidify. This scenario is all very reasonable, but some nagging problems remain. Where-o -where is that crater? 770,000 years ago, a huge meteor hit somewhere on earth and strewed an immense batch of tektites and microtektites over fully 10% of our planet's surface (about 5 x 107 square kilometers). This is called the "Australasian strewn field." Such a recent cataclysm must have left a large and inescapable crater somewhere. The problem is that no one has yet found it. (Ref. 1) Many lines of evidence suggest that ... Science Frontiers ONLINE No. 115: Jan-Feb 1998 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Tektite Mysteries Tektites are small glassy bodies found strewn on and near the surface in several regions of the world. They come in various shapes: droplets, buttons, even dumbbells. By general agreement, tekites are attributed to meteoric or cometary impacts that melt terrestrial rocks and splash liquid droplets into the atmosphere. There they are shaped by aerodynamic forces and solidify. This scenario is all very reasonable, but some nagging problems remain. Where-o -where is that crater? 770,000 years ago, a huge meteor hit somewhere on earth and strewed an immense batch of tektites and microtektites over fully 10% of our planet's ...
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... extinctions are correlated with the 2.3 -million-year date, but there appears to have been a major deterioration of climate at about this time. There was a shift in the marine oxygen isotope records and, more obvious, the creation of the huge loess (sandy) deposits in China. What the impact may have done is to vaporize enough water into the atmosphere to increase the earth's albedo, reflecting sunlight back into space, lowering the average temperature, and thus triggering the Ice Ages. (Kyte, Frant T., et al; "New Evidence on the Size and Possible Effects of a Late Pliocene Oceanic Asteroid Impact," Science, 241:63, 1988.) Comment. Aficionados of the Ice Age problems will have to add this theory to ... Science Frontiers ONLINE No. 59: Sep-Oct 1988 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Did an asteroid impact trigger the ice ages?Asteroids and comets are being blamed these days for more and more of our planet's catastrophism -- biological, meteorological, and geological. What a turnabout in scientific thinking in just a decade. F.T . Kyte et al have now provided additional details on meteoritic debris they first described in 1981. On the floor of the southeast Pacific, about 1400 kilometers west of Cape Horn, about 5 kilometers down, they found high concentrations of iridium in Upper Pliocene sediments about 2.3 million years old. Since the proposed projectile hit in very deep water, no crater was dug ...
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... Science Frontiers ONLINE No. 65: Sep-Oct 1989 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Chemical surprises at the k-t boundary The presence of high iridium concentrations at the Cretaceous-Tertiary (K -T ) boundary, some 65 million years ago, has led to the widely accepted notion that an extraterrestrial projectile slammed into the earth at that time, wreaking geological and biological havoc. But the K-T boundary is anything but simple chemically and paleontologically. To illustrate, J.L . Bada and M. Zhao have found unusual amino acids in sediments laid down before and after this geological time marker. "They find that Danish sediments spanning the narrow boundary layer contain two amino acids, alpha-aminoisobutyric acid and ... , that are relatively uncommon in biological materials but abundant in the organicrich meteorites. They suggest that the body which collided with Earth 65 million years ago and left the telltale iridium residue may have been organic-rich, perhaps like a C-type asteroid or a comet. Such a possibility has interesting implications for the extinction and related atmospheric effects, and supports the idea that impact events could have supplied the Earth during a much earlier period with the raw materials for organic chemical evolution." Actually, the above quotation is pretty much in line with present mainstream thinking. Perhaps so, but Bada and Zhao identified two troubling anomalies. First, the amounts of amino acids found were surprisingly high. How could these complex molecules survive the searing temperatures engendered by high-velocity impact? Second, ...
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... Science Frontiers ONLINE No. 105: May-Jun 1996 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Eight Little Craters All In A Row The recent impact upon Jupiter of a procession of chunks from Comet Shoemaker-Levy 9 has encouraged geologists to look for crater chains here on earth. Such have been spotted on the moon, and it is unlikely the earth escaped such bar rages. Of course, older terrestrial craters are harder to identify due to the ceaseless geological activity here on earth. In the first 1996 number of Geophysical Research Letters, M.R . Rampino and T. Volk describe a possible swath of meteoric devastation across the North American Midwest. "Eight circular geologic structures ranging from about 3 to 17 km in diameter, ... Science Frontiers ONLINE No. 105: May-Jun 1996 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Eight Little Craters All In A Row The recent impact upon Jupiter of a procession of chunks from Comet Shoemaker-Levy 9 has encouraged geologists to look for crater chains here on earth. Such have been spotted on the moon, and it is unlikely the earth escaped such bar rages. Of course, older terrestrial craters are harder to identify due to the ceaseless geological activity here on earth. In the first 1996 number of Geophysical Research Letters, M.R . Rampino and T. Volk describe a possible swath of meteoric devastation across the North American Midwest. "Eight circular geologic structures ranging from about 3 to 17 km in diameter, ...
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... latter insisted on their 700,000-year figure; the former said "maybe so" but the tektites are still found only in very young, superficial sediments. The point here is that time-of-solidification may not be the same as time-of-fall. At stake is the prevailing theory, now dogmatically proclaimed, that tektites are created when a large asteroid impacts the earth, ejecting molten droplets of rock which shower back to earth as solidified tektites. No one has ever found a suitably large crater ( 200 miles in diameter) assignable to the Australasian tektite strewn field. Nevertheless, the impact model prevails; and the young geological age of the tektites is dismissed as erroneous. A Soviet scientist, E.P . Izokh, has recently proposed a radically different ... . The latter insisted on their 700,000-year figure; the former said "maybe so" but the tektites are still found only in very young, superficial sediments. The point here is that time-of-solidification may not be the same as time-of-fall. At stake is the prevailing theory, now dogmatically proclaimed, that tektites are created when a large asteroid impacts the earth, ejecting molten droplets of rock which shower back to earth as solidified tektites. No one has ever found a suitably large crater ( 200 miles in diameter) assignable to the Australasian tektite strewn field. Nevertheless, the impact model prevails; and the young geological age of the tektites is dismissed as erroneous. A Soviet scientist, E.P . Izokh, has recently proposed a ...
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... scenarios. C. Chyba and C. Sagan, in a major review article in Nature, see a two-fold problem: (1 ) identifying the source of the raw materials; and (2 ) identifying the source(s ) of energy required for the synthesis of complex organic chemicals. First, they point to the steady drizzle of tiny, organic-rich particles drifting down to earth from cometary debris. These particles, which even carry spacesynthesized amino acids down to the earth's surface, seem likely chemical precursors of life. However, the atmosphere is also a potential source of prebiotic chemicals -- providing energy sources are available. Chyba and Sagan suggest as sources: lightning, ultraviolet radiation, and the shock energy derived from meteorite/asteroid/comet impacts. Together ... energy sources, especially ultraviolet light, might synthesize thousands of tons of complex organic compounds each year. (Chyba, Christopher, and Sagan, Carl; "Endogenous Production, Exogenous Delivery and Impact-Shock Synthesis of Organic Molecules: An Inventory for the Origins of Life," Nature, 355:125, 1992. Also: Henbest, Nigel; "Organic Molecules from Space Rained Down on Early Earth," New Scientist, 2. 27, January 25, 1992.) Comment. Little is said in either of the above articles about the nature of and impetus for that final elusive step from organic chemicals to the simplest life forms. Everyone assumes that it happened, but did it? One can always imagine a universe in which matter, energy, and life have always existed ...
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... Science Frontiers ONLINE No. 101: Sep-Oct 1995 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Ironclad proof of the moon's origin? Did earth and moon "coaccrete" at the same time? That is, did two clouds of debris simultaneously collect and coalesce into two rough spheres, which then began orbiting about a common center of gravity? Or, perhaps the earth and moon were once a single mass that ultimately fissioned due to the gravitational tugging of a passing massive object. If either of these scenarios were correct, earth and moon would have similar bulk compositions. This, however, does not seem to be the case. The abundance and distribution of iron on the moon's surface, as measured by the ... probe Clementine , indicates that the moon is richer than the earth in refractory (high meltingpoint) compounds. The moon, therefore, almost certainly originated elsewhere, contrary to what most astronomers have longbelieved. Given the constraints of celestial mechanics, the most likely hypothesis postulates a colossal impact involving protoearth and the interloping protomoon. After considerable havoc, the two battered spheres settled down into their present configuration. Thus expire the two most popular theories of the moon's origin. (Lucey, Paul G., et al; "Abundance and Distribution of Iron on the Moon," Science, 268:1150, 1995) From Science Frontiers #101 Sep-Oct 1995 . 1995-2000 William R. Corliss ...
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... Science Frontiers ONLINE No. 99: May-Jun 1995 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Ballistic Panspermia Scientists are already convinced that cratering events on the moon and Mars have propelled rocky debris in the direction of the earth, and that some of these fragments have landed here in the guise of meteorites. A logical question is: Can life forms and/or chemical precursors of life be transported thus across the far reaches of the solar system? Can one planet infect another ballistically? An analysis by M.K . Wallis and N.C . Wickramasinghe is rather warm towards this idea: "The mass of escaping ejecta from the presumed 10-km comet that caused the 180-km Chicxulub crater, with a radius of ... 10 km and 1 m deep, amounted to ~300 Mm3 , of which one third may have been rock and 10% higher-speed ejecta that could have transited directly to Mars. It may have taken 10 Ma to impact Mars but...the probability is not exceedingly low but 0.1 -1 %. "The survival and replication of microorganisms once they are released at destination would depend on the local conditions that prevail. Although viability on the present-day Martian surface is problematical, Earth-to-Mars transfers of life were feasible during an earlier 'wet' phase of the planet, prior to 3.5 Ga ago. The Martian atmosphere was also denser at that epoch, with several bars of CO2 , thus serving to decelerate meteorites, as on ...
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... 1982 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Gravity Anomaly Ripples Centered In Canada When scientists recently examined gravity anomaly data for North America, strange circular ripples appeared to surround a point near Hudson Bay. These ripples seem to have spread out like those from a pebble dropped into a pond, but here the ripples are actually ancient density variations in the earth's crust, now covered over by thick sediments. One hypothesis is that a 60-90 kilometer meteorite smashed into the earth some 4 billion years ago, wrinkling the young surface for several thousand kilometers in all directions around a colossal crater. Magma welling up in the crater solidified creating the nucleus of the North American continent. It is quite possible that the other continents began their existences ... this way -- meteor impact. The gravity data that led to this hypothesis have been available for some time but apparently no one ever looked at them with continental patterns in mind. (Simon, C.; "Deep Crust Hints at Meteoric Impact," Science News, 121:69, 1982.) Comment 1: John Saul has discovered surface indications of immense ring structures in the American southwest. See ETC2 in our Catalog: Carolina Bays, Mima Mounds, which is described more fully here . Comment 2: If all our continents were initiated by meteor impacts, and if they were once clustered together in a supercontinent, as postulated by Continental Drift, then the incoming meteorites would have to have been focussed on a restricted portion of the earth's surface; that is ...
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... 1986 Other pages Home Page Science Frontiers Online All Issues Last Issue Next Issue Sourcebook Project Sourcebook Subjects Contents Archaeology Explaining the Nazca Lines Humans in the Americas 32,000 Years Ago? Astronomy Lumps, Clumps, and Jumps Clump of Antimatter 1986: "Tired Light" Revived Again Biology Something Big Down There! Brain Architecture: Beyond Genes Heretical Evolutionary Theory The Chromosome Gap How the Cheetah Lost its Stotts Earth's Womb Geology Oil & Gas From the Earth's Core Oceans From Outer Space? Continental Graveyard? Two Points of Great Impact Geophysics A True Fish Story Booming Dunes Another Luminous Aerial Bubble Psychology Magnetic Theory of Dowsing Chemistry & Physics Unpredictable Things ...
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... Science Frontiers ONLINE No. 87: May-Jun 1993 Other pages Home Page Science Frontiers Online All Issues Last Issue Next Issue Sourcebook Project Sourcebook Subjects Contents Archaeology The 50,000-year-old americans of pedra furada The zuni enigma The american discovery of europe! Astronomy The earth: a doubly charmed planet Cosmic soot and organic asteroids Biology Fossil feathers fly Is caddy a mammal? The uniqueness of human adolescence Animals attack human technological infrastructure Late survival of mammoths Geology Whence the earth's pulse? Giant impact-wave deposit along u.s . east coast Geophysics The vent glow and "blind" shrimp Amazons in the sky The bottle-green icebergs of antarctica Psychology Alien abuctions: were they, are they real? Calculating prodigies, gnats, and smart weapons ...
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... Science Frontiers ONLINE No. 120: Nov-Dec 1998 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Gaia as a super-superorganism The Gaia hypothesis states that the earth's environment is maintained suitable for life by life itself. Our climate, atmospheric oxygen level, ocean composition, and similar vital conditions are kept livable by life's waste products, such as the oxygen emissions of plants. That something like Gaia is required is seen in the extreme disequilibrium of the earth's atmosphere compared to the near-equilibrium of the atmospheres of apparently lifeless Venus and Mars. For example, our atmosphere's 21% oxygen, a highly reactive gas, is many orders of magnitude higher than one would expect on a lifeless planet ... Furthermore, life-friendly conditions have been maintained for billions of years despite large changes in the sun's output and the traumas of asteroid impacts. T.M . Lenton, writing in Nature, asks a salient question: How has planetary self-regulation (Gaia) been established and maintained by evolution and natural selection which operate on the level of individuals? In other words, evolution tells us that organisms should evolve so as to leave the most progeny not so as to regulate the atmosphere. Lenton answers that there must be feedback loops from the planetary environment that steer the evolution of individuals in the "proper" direction. Lenton goes on to explore some of these many feedback mechanisms; one obscure loop involves the production of dimethyl sulfide by marine phytoplankton. Truly, it is ...
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... All Issues Last Issue Next Issue Sourcebook Project Sourcebook Subjects Contents Archaeology Two Remarkable Inscribed Stones Astronomy Thou Canst Not Stir A Flower, Without Troubling of A Star Natural Laser Beacons A Mysterious Object Biology Subtle is the Virus An Ocean Full of Viruses An Even Larger Ocean of Life Spores Still Viable After 7,000 Years Animals As Nutrient Carriers Geology Terranes Continue to Pile Up Grand Canyon Shamed Again When the Earth Shifted Gears The Oklo Phenomenon and Evolution Earth's Magnetic Field Jerks Osmium Isotopes Support Meteoric Impact Geophysics Incredible Phosphorescent Display on the China Sea Ball Lightning Splits and Recombines Inside Soviet Airliner Booms Startle Arkansas Psychology Mental Deflection of Cascading Spheres What Makes A Calculating Prodigy? False Pregnancies in Males Unclassified The 'Great Silence'; Or Why Aren't Aliens Landing on the White House Lawn? ...
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... have ignited it almost immediately if it was concentrated enough. A colossal firestorm might have then enveloped the entire planet. The whole atmosphere could have been afire. This, according to B. Hurdle and colleagues at the Naval Research Laboratory, who speculate that the dinosaur hegemony may ended suddenly in flames rather than in a long, drawn-out whimper. (Day, Michael; "Hell on Earth," New Scientist, p. 5, November 20, 1999) 55 million years ago. Ten million years after the dinosaurs may have roasted in a global firestorm, another methane burp may have erupted from the oceans. This burp was slower and did not ignite but was just as lethal. It filled with atmosphere with a highly effective green-house: methane. The result was ... Science Frontiers ONLINE No. 128: MAR-APR 2000 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Burps of Death Not only did the poor dinosaurs have to contend with an asteroid impact and a lurch of the poles, but also with the possible ignition of voluminous methane burps. 65-million years ago. This was the time of the well-publicized, but still hypothetical, asteroid impact. It is said to have wreaked havoc on our wounded planet and, especially, the dinosaurs. Volcanos spewed out vast lava fields and filled the air with greenhouse gases and dust. It was a bad time for many life forms. Actually, It may have been far worse than generally advertised. In addition to the volcanic activity and climate ...
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... Science Frontiers ONLINE No. 34: Jul-Aug 1984 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Behind magnetic flip-flops The earth's magnetic field frequently reverses its polarity. Such flips can of-ten be correlated with climate changes, global ice volumes, sea-floor spreading rates, and deposition of black shales, tektite falls, biological extinctions, etc. The frustrating thing is the lack of clear-cut cause and effect; that is, how these phenomena are linked physically to the geomagnetic field. Part of the problem is that we can only guess at how the geomagnetic field is generated. Let us assume that the earth's magnetic field is created by dynamo action in the planet's fluid core. ... due to fluctuations in core turbulence caused by two competing energy sources: heat loss at the mantle-core boundary and progressive growth of the inner core. In concept, the heat lost at the core-mantle boundary might be linked to climate changes and sea-floor spreading. Taking a different tack, D. Gubbins has investigated the possibility that field reversals are triggered by ice ages and meteorite impacts (tektite falls). The physical mechanism here would be the increase in pressure upon the core, which affects the rate of freezing in the outer core, and thus the power available to the core dynamo. Gubbins found that these externally caused pressure changes were too small to explain the polarity changes. However, the parameters involved are not well-known, and external triggers cannot yet be ...
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... Science Frontiers ONLINE No. 42: Nov-Dec 1985 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Can spores survive in interstellar space?There is good evidence that life appeared on earth just 200-400 million years after the crust had cooled (assuming conventional methods of measuring age). Two hundred million years seems a bit on the short side for the spontaneous generation of life, although no one really knows just how long this process should take (forever?). The apparent rapidity of the onset of terrestrial life has led to a reexamination of the old panspermia hypothesis, in which spores, bacteria, or even nonliving "templates" of life descended on the lifeless but fertile earth from interstellar space. P. Weber and J ... of tens or hundreds of million years are indicated by the experiments. Under such conditions, the interstellar transportation of life is possible. But perhaps the injection and capture phases of panspermia might be lethal to spores. Weber and Greenberg think not -- under certain conditions. The collision of a large comet or meteorite could inject spores from a life-endowed planet into space safely, particularly if the impacting object glanced off into space pulling ejecta after it. The terminal phase, the capture of spores from a passing molecular cloud by the solar system and then the earth, would be nonlethal if the spores were somehow coated with a thin veneer of ultraviolet absorbing material. In sum, the experiments place limits on panspermia, but do not rule it out by any means. (Weber, Peter ...
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... m in diameter." There are ten gouges in all, strung out along 50 kilometers. The scars are young, perhaps only a few thousand years old, well within the time of human habitation. Schultz and Lianza also found pieces of meteoritic rock and glassy fragments of impact melt. (Schultz, Peter H., and Lianza, Ruben E.; "Recent Grazing Impacts on the Earth Recorded in the Rio Cuarto Crater Field, Argentina," Nature, 355:234, 1992. Also: Monastersky, R.; "Meteorite Hopscotched across Argentina," Science News, 141:55, 1992.) Comments. Note the similarities to the much more numerous Carolina Bays. See ETB1 in our catalog: Carolina Bays, Mima Mounds, Submarine Canyons. For ordering information ... the Argentine pampas near Rio Cuarto. "During routine flights two years ago .. ., one of us (R .E .L .) noticed an anomalous alignment of oblong rimmed depressions (4 km x 1 km) on the otherwise featureless farmland of the Pampas of Argentina. We argue here, from sample analysis and by analogy with laboratory experiments, that these structures resulted from lowangle impact and ricochet of a chondritic body originally 150-300 m in diameter." There are ten gouges in all, strung out along 50 kilometers. The scars are young, perhaps only a few thousand years old, well within the time of human habitation. Schultz and Lianza also found pieces of meteoritic rock and glassy fragments of impact melt. (Schultz, Peter H., and Lianza ...
Terms matched: 2 - Score: 221 - 15 May 2017 - URL: /sf080/sf080g11.htm
... "dust-veil" event of 536 AD was blamed on a huge volcanic eruption. Work by M.G .L . Baillie now casts doubt upon interpretation. "Now tree-ring data, published by Professor Mike Baillie of Queens University of Belfast, has brought catastrophes almost into modern times. The tree rings show that in the mid 530s -- just about the time civilisation on Earth suffered a sharp setback -- there was a sudden decline in the rate of tree growth which lasted about 15 years. Clearly, something dramatic had happened. "There are two possibilities: a huge volcanic eruption or a collision between the Earth and a solid object: an asteroid or comet. Ice-cores drilled from Greenland show no evidence of large-scale volcanic activity at that time ... so Professor Baillie and others now believe a cosmic impact is more likely. The result would have been to throw up a huge veil of dust and debris, cooling the Earth and producing widespread crop failures." (Anonymous; "Raining Death and Dark Ages," London Times, July 27, 1994. Cr. A. Rothovius) In the scientific literature, Baillie has elaborated on the cosmic-projectile theme, adding that the dust veil could also have been created when the solar system passed through a cloud of cosmic dust. (Baillie, M.G .L .; "Dendrochronology Raises Questions about the Nature of the AD 536 Dust-Veil Event," The Holocene , 4:212, 1994. Cr. L. Ellenberger) Comment. The scientific literature hints ...
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... clays from five sites in Europe and New Zealand are 102 -104 -fold enriched in elemental C (mainly soot), which is isotopically uniform and apparently comes from a single global fire. The soot layer coincides with the Ir layer, suggesting that the fire was triggered by meteorite impact and began before the ejecta had settled." The composition of the hydrocarbons in the sediments points to the earth's biomass (mainly surface vegetation) as the source of the soot. The total quantity of K-T soot is equivalent to that which would be produced by burning 10% of all present terrestrial plant material. (Wolbach, Wendy S., et al; "Global Fire at the Cretaceous-Tertiary Boundary," Nature, 334:665, 1988.) Comment. ... S . Wolbach et al. Here is their Abstract: "Cretaceous-Tertiary (K -T ) boundary clays from five sites in Europe and New Zealand are 102 -104 -fold enriched in elemental C (mainly soot), which is isotopically uniform and apparently comes from a single global fire. The soot layer coincides with the Ir layer, suggesting that the fire was triggered by meteorite impact and began before the ejecta had settled." The composition of the hydrocarbons in the sediments points to the earth's biomass (mainly surface vegetation) as the source of the soot. The total quantity of K-T soot is equivalent to that which would be produced by burning 10% of all present terrestrial plant material. (Wolbach, Wendy S., et al; " ...
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... ice sheet carries these meteorites conveyor-belt fashion out towards the encircling seas. But where Antarctic mountains get in the way, the rocky cargo tends to get concentrated. Several thousand meteorites have already been picked up at these favored spots. In just a few brief summers of searching, these massive finds have posed unexpected questions. Here is a sampling. The terrestrial ages (times since arrival on earth) measure between 1,000 and 700,000 years, implying that the Antarctic ice sheet may be at least 700,000 years old. This is unfortunate for several proposed scenarios of recent catastrophism, which envision an iceless Antarctica. At least 20 amino acids appear in the more than 40 carbonaceous chondrites picked up with sterile equipment. These meteorites are dated as 4.5 billion years ... , or 1 billion years older than the earliest terrestrial life found in the rocks. These finds highlight the old question: Did meteorites seed life on earth? The much-publicized "lunar" meteorite, supposedly blasted out of the moon's crust by asteroid impact, thence falling to earth, shows little evidence of mechanical shock. If this meteorite, with a composition so similar to the Apollo samples is not from the moon, where did it come from? (Marvin, Ursula B.; "Extraterrestrials Have Landed on Antarctica," New Scientist, 97:710, 1983.) From Science Frontiers #27, MAY-JUN 1983 . 1983-2000 William R. Corliss ...
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