Terrestrial Impact Craters caused by Asteroids
Meteorites and Cometary Debris
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Kara-Kul crater, Tajikistan, Central Asia
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Barringer's Meteor crater, Arizona, USA
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Wolfe Creek crater, Australia
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Comets & Asteroids Skywatching Calendar 2008
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Impact Craters throughout the Solar System Earth
Africa
Vredefort Crater -
Morokweng Crater -
Oasis Crater -
Gweni-Fada Crater -
Aorounga Crater -
FULL LIST OF
Asia
Popigai Crater -
Kara Crater -
Kara-Kul Crater -
Elgygytgyn Lake Crater -
Zhamanshin Crater -
FULL LIST OF
Australasia
Acraman Crater -
Woodleigh Crater -
Tookoonooka Crater -
Yarrabubba Crater -
Gosses Bluff Crater -
FULL LIST OF
Europe
Lake Siljan Crater -
Keurusselkä Crater -
Kamensk Crater -
Lake Lappajärvi Crater -
Boltysh Crater -
FULL LIST OF
North America
Sudbury Basin Crater -
Lake Manicouagan Crater -
Chesapeake Bay Crater -
Charlevoix Crater -
Montagnais Crater -
FULL LIST OF
South America
Chicxulub Crater -
Pantasma Crater -
Araguainha Crater -
Iturralde Crater -
Vargeão Dome Crater -
FULL LIST OF Earth's Moon
FULL LIST OF Mercury
FULL LIST OF Venus
FULL LIST OF Mars
Martian crater in Mamers Valles
FULL LIST OF Links to other sites The Largest Impact Crater in the Solar System Interactive Asteroid Impact Sites Map Chronological List of Terrestrial Impact Craters Do the building blocks of life travel throughout the universe on comets and on asteroids? Below is a small selection of books suggesting that it probably does
"Life in the Universe: A Beginner's Guide To Astrobiology" "An excellent introduction into the newly emerging and exciting field of astrobiology. An essential, enjoyable and highly readable insight into life in its cosmic context."
"Planets and Life: The Emerging Science of Astrobiology" "Astrobiology involves the study of the origin and history of life on Earth, planets and moons where life may have arisen, and the search for extraterrestrial life. It combines the sciences of biology, chemistry, palaeontology, geology, planetary physics and astronomy. This textbook brings together world experts in each of these disciplines to provide the most comprehensive coverage of the field currently available."
"Complete Course in Astrobiology" "This up-to-date resource is based on lectures developed by experts in the relevant fields and carefully edited by the leading astrobiologists within the European community. Aimed at graduate students in physics, astronomy and biology and their lecturers, the text begins with a general introduction to astrobiology, followed by sections on basic prebiotic chemistry, extremophiles, and habitability in our solar system and beyond."
"Astrochemistry: From Astronomy "The dynamic field of astrochemistry brings together ideas of physics, astrophysics, biology and chemistry to the study of molecules between stars, around stars and on planets. Astrochemistry: from Astronomy to Astrobiology provides a clear and concise introduction to this rapidly evolving multidisciplinary subject. Starting with the Molecular Universe, the text covers the formation of the elements, simple models of stars and their classification. It then moves on to draw on the theme of the Origins of Life to study interstellar chemistry, meteorite and comet chemistry as well as the chemistry of planets."
"Fitness of the Cosmos for Life: Biochemistry and Fine-Tuning" "This highly interdisciplinary book highlights many of the ways in which chemistry plays a crucial role in making life an evolutionary possibility in the universe. Cosmologists and particle physicists have often explored how the observed laws and constants of nature lie within a narrow range that allows complexity and life to evolve and adapt. Here, these anthropic considerations are diversified in a host of new ways to identify the most sensitive features of biochemistry and astrobiology. Celebrating the classic 1913 work of Lawrence J. Henderson, The Fitness of the Environment for Life, this book looks at the delicate balance between chemistry and the ambient conditions in the universe that permit complex chemical networks and structures to exist."
"Astrobiology: A Multi-disciplinary Approach" "Astrobiology: A Multidisciplinary Approach is the most comprehensive textbook available for emerging upper-level courses in astrobiology. Internationally renowned authority Jonathan Lunine gives students with a variety of backgrounds a solid foundation in the essential concepts of physics, chemistry, biology, and other relevant sciences to help them achieve a well-rounded understanding of the fascinating study of the origin of life, planetary evolution, and life in the cosmos."
"National Geographic Video
DVD Region 1 "Asteroids and comets: Every year, millions of these "stray bullets" streak through the skies, and tons of small meteorites strike our planet! Some 65 million years ago, dinosaurs were wiped off the face of the earth - in what many believe was the aftermath of a massive cosmic collision. Could something like this happen again? Scientists believe that the impact of an asteroid only a mile wide would be globally catastrophic."
"Comets II" "Comet science is a field that has seen tremendous advances in recent years, far surpassing the knowledge reflected in the original Comets volume published as part of the Space Science Series in 1982. This new volume, with more than seventy contributing authors, contains the most extensive collection of knowledge yet assembled in the field. It will enable scientists involved in their study to make connections across disciplinary boundaries and will set the stage for discovery and new understanding in the coming years."
"Cometary Science after Hale-Bopp, Volume I" "Comet Hale-Bopp defines a milestone event for cometary science: it is the first "really big" comet observed with modern equipment on the ground and from space and due to that; it is considered the new reference object in cometary sciences. At the beginning of a new era in spacecraft exploration of comets and five years after Hale-Bopp's perihelion passage these proceedings of invited and contributed papers for IAU Colloquium 186 "Cometary Science after Hale-Bopp" review the state-of-the-art knowledge on comets, the icy, dusty and most primordial left-overs of the formation disk of our own solar system." |
For many years academics in the historical sciences were content in their belief that terrestrial impacts by solid bodies from space was something that only happened in the very early history of our planet, whilst the average person had never heard the word 'asteroid'. Then in 1980 the Nobel prizewinning physicist, Luis Alvarez, and his colleagues published their famous paper in "Science" which argued that a cosmic impact had led to the extinction of the dinosaurs. He showed that large amounts of the element iridium present in geological layers dating from about 65 million BP had a cosmic origin, and proposed a radical theory that it was a massive 'asteroid impact' 65 million years ago which finally wiped out the dinosaurs. Over the following decade interest began to rise in the idea of 'terrestrial impacts', and by 1990 most scientists at least accepted that the craters on our Moon were caused by impacts of cometary debris and asteroids of varying sizes, and not the volcanoes they had previously thought responsible. As space exploration continued, the images sent back to Earth (by the Voyager spacecraft especially) allowed astronomers to build a picture of the sort of dynamic solar system first suggested by Victor Clube and Bill Napier in their groundbreaking books "Cosmic Serpent" (published 1982) and "Cosmic Winter" (published 1990). This was a new model of the solar system. One where regular influxes of comets from the various areas of space transitted by our solar system in its orbit through the galaxy suggested inevitable, and multiple, collisions with all the planetary bodies and their respective moons. Technologicl advances in space imaging have since shown a multitude of impact craters on all the inner planets and their moons. But some 12 years after the theories about the cosmic impact which led to the extinction of the dinosaurs were first proposed, the possibility of cometary bombardments still seemed something that belonged way back in the very early history of our solar system - even to most scientists. It was on March 24 1993 that astronomers, husband and wife team Carolyn S. and Eugene M. Shoemaker, and David H. Levy, discovered a new comet in our solar system. Observations over the next few months determined that the comet was "at least temporarily" in orbit around Jupiter, and that on July 7 1992 the tidal forces of the largest planet in our solar system had caused the comet, by then named P/Shoemaker-Levy 9, to disintegrate. Over the next year or so astronomers on Earth observed the fragments proceed around the Sun and head back on a collision course directly for Jupiter. From July 16 to 22nd 1994 they watched with awe as the 21 fragments bombarded the visible surface of Jupiter causing 'fireballs 50 times the size of Earth' and leaving huge scars on Jupiter's southern hemisphere. This was a wake-up call even for those who understood what was going on, and resulted in more funding being requested by astronomers to research into the frequency of impacts throughout the solar system, but also to search for any evidence of past impacts on Earth. Following the abrupt realisation that 'if it can happen to Jupiter now, it can happen to Earth in the future', the search began in earnest to identify the orbital paths of all Earth-crossing objects. If anyone is in any doubt as to exactly how dangerous a place our planet occupies in the solar system they should simply look at our Moon. There for all to see, with the naked eye, and in even greater detail using a pair of good binocular or a small telescope, are impact craters galore. There doesn't appear to be one square mile of the lunar surface that is not pockmarked with impact craters, and while some are undoubtedly very ancient they also contain within their crater rims a myriad newer craters from much more recent impacts. The reason why there are so many visible craters on the Moon form ancient impacts was summed up well by astronomer, Duncan Steel, in his 1995 book, "Rogue Asteroids and Doomsday Comets": "Craters are relatively swiftly eroded on Earth by rain, snow, and wind, whereas on the Moon they remain for eons until a new projectile happens to erase the scar left by some cousin countless millennia before." So this explains, partially, why there are so few visible craters on Earth. But raises the obvious question as to why we can't see more given that, if our Moon is is so cratered, surely our planet must be an even bigger target in the same area of the solar system? The answer is at once simple and also very complex. Firstly, there is approximately 71% of the surface area of the Earth covered with oceans - leaving just 29% dry land surface area. This gives a 3 to 1 chance that any incoming impactor will, if it doesn't explode a few miles up like whatever happenned at Tunguska in 1908, impact one of the oceans and leave no easily visible trace. Secondly, any crater on dry land would be at the mercy of the elements, and should there have been collisions with cometary debris, or asteroids, in the Amazon Basin, say, then vegetation would without doubt obscure them in a very short time indeed. But these are not the only factors, as Duncan Steel explained: "The length of time that a crater will survive depends not only on the regions in which it is formed, but also on it's size. Obviously a crater 50 kilometers across will last longer than a comparatibe pipsqueak just 100 meters in diameter. For example, in Australia there are 19 known craters - probably there are dozens more awaiting discovery - and of those, four are less than about 6,000 years old. Those are the four smallest however, all being less than 200 meters in diameter." At the time that Duncan Steel was writing "Rogue Asteroids and Doomsday Comets" in 1994/1995, there were then only about 140 known terrestrial impact craters. But in the 9/10 years since then, spurred on by a new-found sense of urgency following the events on Jupiter in July 1994, the search picked up steam, and many more have been discovered. The current tally is in the region of 180 , and there is an interactive map of all the terrestrial impact craters accessible at the University of Arizona website. This is an excellent resource for anyone wishing to see just how many have so far been discovered on just the 29% of the surface area of our planet that is currenly dry land. Another good resource for information about terrestrial impact craters which also has an interactive map is accessible at the University of New Brunswick Canadian website. The first paragraph or so of their introduction to the subject is worth quoting from here, as it puts the dynamic history of the solar system into a proper perspective: "Until recently, impacts by extraterrestrial bodies were regarded as an interesting but, perhaps, not an important phenomenon in the spectrum of geological process affecting the Earth. Our concept of the importance of impact processes, however, has been changed radically through planetary exploration, which has shown that virtually all planetary surfaces are cratered from the impact of interplanetary bodies. It is now clear from planetary bodies that have retained portions of their earliest surfaces that impact was a dominant geologic process throughout the early solar system. For example, the oldest lunar surfaces are literally saturated with impact craters, produced by an intense bombardment which lasted from 4.6 to approximately 3.9 billion years ago, at least a 100 times higher than the present impact flux. The Earth, as part of the solar system, experienced the same bombardment as the other planetary bodies." On this page we have tried to compile a photographic collection of impact craters on Earth to demonstrate just how many there actually are. Asteroids vary in their composition. Some are composed purely of stoney materials, some are composed of nickel & iron, while others have varying combinations of both. It should be understood that many of the asteroids which are made up of stoney materials do not survive the journey through our atmosphere. They explode in the upper atmosphere as the white-hot matter caused by friction upon entry hits the freezing cold air. This has happened as recently as 1908 over the Tunguska region of Siberia, where the 'air-burst' caused an explosion the equivalent of many hundreds of nuclear bombs. Because the asteroid, or fragment of cometary debris, detonated in the upper atmosphere there was no impact crater to show what had happened, but many thousands of square miles of forest lands were completely flattened all around the detonation area. The Tunguska airburst, Siberia - June 1908
How many times has this happened before? And how soon will it be before an something like this happens again? ...
100 Years Since The Tunguska Event
It has now been 100 years since the events of June 30, 1908, when a bolide of some description exploded over the Tunguska River region of Siberia. A conference to mark the anniversary is currently underway in Moscow, Russia. TUNGUSKA 2008 INTERNATIONAL CONFERENCE
"Tunguska: 100 years of wondering" One hundred years ago, an explosion bigger than an atomic bomb blasted Tunguska, Siberia. We still don't know what caused it, but there are plenty of theories!
In 1991, Italian scientists still found evidence of fallen trees near the blast site
Early on the morning of June 30, 1908, a massive explosion rocked the Siberian wilderness flattening more than 2,000 square kilometres of forest. Villagers 100 kilometres away from the Podkamennaya Tunguska river basin reported seeing a fireball in the sky, feeling intense heat, hearing loud thumps and being thrown off their feet. 'The split in the sky grew larger, and the entire Northern side was covered with fire. At that moment I became so hot that I couldn't bear it, as if my shirt was on fire; from the northern side, where the fire was, came strong heat.' 'I wanted to tear off my shirt and throw it down, but then the sky shut closed, and a strong thump sounded, and I was thrown a few yards', reported one villager. The explosion lit up the sky as far away as London for several days. Nearly two decades later, the first expedition into the area led by Russian meteorite specialist Leonid Kulik found a region of scorched trees 50 km in diameter, but no crater. It's now believed that the Tunguska event — as it's now known — was hundreds of times more powerful than the atomic bomb dropped on Hiroshima Tunguska has long fascinated scientists, enthusiasts and sci-fi fans. Over the years, the mystery of the event has prompted a number of theories with varying degrees of scientific plausibility. These have ranged from a meteorite to the crash of an alien spacecraft; an explosion of methane or the result of Nikola Tesla's experiments with electricity near New York." [Full Story]
Geographic Distribution of Known Impact Structures
Terrestrial Impact Craters
"Lake Janisjarvi Impact Crater
"Lake Jänisjärvi is a roughly oval-shaped lake, some 13 by 17 kilometers (8 by 11 miles) across, in northwestern Russia, near the Finnish border. The basin for this lake was formed hundreds of millions of years ago by a meteorite impact. On September 5, 1999, NASA’s Landsat-7 satellite captured this image of Lake Jänisjärvi and its surroundings. This late-summer shot shows a lush green landscape free of snow and ice. Land around the lake appears in varying shades of green, interrupted by tan and pink swaths of cleared (probably agricultural) land, particularly in the east. The lake itself is deep blue, dotted with diminutive islands. A close look at the lake’s ragged contours indicates that the this water body is connected to many others in the area. The tiny tributary exiting this lake’s southern edge meanders toward Lake Ladoga to the south." [Full Story]
"Spider Crater, Western Australia
"The craters discovered recently near Dukhan, 90km west of Doha, are of unusual shape, according to Qatari astronomical observer and active member of Qatar Scientific Club Sheikh Salman bin Jabor Al Thani. Images of these craters, believed to have been formed following meteor impact nearly seven decades ago, were presented by Sheik Salman at Doha Scientific Club on Sunday. The craters discovered have an upward curve rather than a depression as in normal craters. The soft nature of the sand in the site can be accounted for this shape. Pillar like structures of sand have been found in the crater. The studies on the sand structures have found that they were formed very fast rather than over time. The high temperature during the impact, which might have led to the boiling of the water salt and sand, can explain the formation of these structures. 'The area was marshy when the meteorite hit. There had been stories of camels being sucked into the earth from this place long back. Now due to industrialization, the water content of the area has decreased; most have dried up and become deserts', Sheikh Salman said. The studies have shown that there is a high density in salt content in the area even today." [Full Story]
"Discovery with deep impact on Scots coast" "It is a mystery which has puzzled generations of geologists – the origins of a layer of stratified rock trapped in the sediments which now form part of the coastline of north-west Scotland. Scientists suspected for years that the curious seam could have been formed by volcanic activity millions of years ago. But it was revealed yesterday that the 40-mile long rock layer was formed when the biggest meteorite ever to strike what is now the British Isles hit the Earth close to present-day Ullapool with the force of a 145,000 megaton bomb. Geologists at Aberdeen and Oxford universities, who made the discovery, believe that the rock was formed by ejecta – material which was forced out of the Earth – by the meteorite, it hit 1.2 billion years ago. The meteorite, which is thought to have measured up to 1km across, would have formed an impact crater up to 10km in diameter, but the material ejected by the impact spread out for at least 50km.
Ken Amor, one of the leaders of the team of geologists involved in the discovery, said: 'This is the most spectacular evidence for a meteorite impact within the British Isles to date, and what we have discovered about this meteorite strike could help us understand the ancient impacts that shaped the surface of other planets, such as Mars.'"
"UK's biggest meteorite impact "It's lucky for the good burghers of Ullapool in Scotland that they weren't around 1.2 billion years ago, because it was around then that the biggest meteorite ever to hit the British Isles would have made a bit of a dent in local house prices. That's according to the combined forces of the University of Oxford and the University of Aberdeen, who say that 'unusual rock formations' previously thought to have volcanic origins are actually the debris ejected from a meteorite strike which threw material over an area 50km across. The volcanic theory has always had geologists scratching their heads, since there are 'no volcanic vents or other volcanic sediments nearby'. The researchers moved in for the kill by taking rock samples in 2006, and have now published their revelations in the journal Geology. Ken Amor of Oxford Uni’s Department of Earth Sciences, explained: 'Chemical testing of the rocks found the characteristic signature of meteoritic material, which has high levels of the key element iridium, normally only found in low concentrations in surface rocks on Earth. We found more evidence when we examined the rocks under a microscope; tell-tale microscopic parallel fractures that also imply a meteorite strike.'" [Full Story]
"Craters found near Dukhan
"The craters discovered recently near Dukhan, 90km west of Doha, are of unusual shape, according to Qatari astronomical observer and active member of Qatar Scientific Club Sheikh Salman bin Jabor Al Thani. Images of these craters, believed to have been formed following meteor impact nearly seven decades ago, were presented by Sheik Salman at Doha Scientific Club on Sunday. The craters discovered have an upward curve rather than a depression as in normal craters. The soft nature of the sand in the site can be accounted for this shape. Pillar like structures of sand have been found in the crater. The studies on the sand structures have found that they were formed very fast rather than over time. The high temperature during the impact, which might have led to the boiling of the water salt and sand, can explain the formation of these structures. 'The area was marshy when the meteorite hit. There had been stories of camels being sucked into the earth from this place long back. Now due to industrialization, the water content of the area has decreased; most have dried up and become deserts', Sheikh Salman said. The studies have shown that there is a high density in salt content in the area even today." [Full Story]
"Satellite image reveals new crater"
"Next time you’re virtually roaming Google Earth, make sure you take a close look at any unusual landforms. Geologist Arthur Hickman did just that, and is now the proud parent of the Hickman Crater, a meteorite crater in the Hamersley Ranges. Dr Hickman, from the Geological Survey of Western Australia, was using Google Earth to look for iron ore when he noticed an unusually circular structure. He sent a Google Earth picture of the structure to his colleague Dr Andrew Glickson at the Australian National University, who later visited the area and confirmed that Dr Hickman had found a particularly well preserved meteorite crater. The crater is 270m across (around the size of the MCG) and is just 35km north of Newman, but hadn’t been previously discovered." [Full Story]
"Meteorite Crater in Puno, Peru Declared
"The area where a meteorite landed in Puno, approximately 800 miles from Lima, has been declared a National Cultural and Natural Heritage Site by the Regional Government of Puno, Peru, said the region's president, Pablo Hernán Fuentes Guzmán. The regional president explained that the meteorite crater was being declared a part of Peru's heritage to preserve it and keep it safe from locals and foreigners that "want to get their hands on it". The meteorite, which was found to be a chondrite, landed in the town of Carancas near the Peru-Bolivia border on September 15, leaving a crater approximately forty feet in diameter." [Full Story]
"Ancient crater discovered under the Delta" A meteorite the size of four Wal-Mart Supercenters likely plunged into what we now know as the Delta millions of years ago, according to a geologist and his teenage son. The duo recently found what they believe to be a 3.4-mile-wide crater buried far beneath the asparagus fields of Victoria Island, about 15 miles west of Stockton. The discovery was entirely by accident. Geologist Bennett Spevack of San Diego works for a firm that was drilling in search of oil; while poring over data, he found a circular depression. [Full Story]
"Ancient killer crater found
Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs - an impact that they believe caused the biggest mass extinction in Earth's history. The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years - the time of the Permian-Triassic extinction, when almost all animal life on Earth died out. Its size and location - in the Wilkes Land region of East Antarctica, south of Australia -- also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward. [Full Story]
"Largest crater in the great Sahara discovered Researchers from Boston University have discovered the remnants of the largest crater of the Great Sahara of North Africa, which may have been formed by a meteorite impact tens of millions of years ago. Dr. Farouk El-Baz made the discovery while studying satellite images of the Western Desert of Egypt with his colleague, Dr. Eman Ghoneim, at BU’s Center for Remote Sensing. The double-ringed crater – which has an outer rim surrounding an inner ring – is approximately 31 kilometers in diameter. Prior to the latest finding, the Sahara’s biggest known crater, in Chad, measured just over 12 kilometers. According to El-Baz, the Center’s director, the crater’s vast area suggests the location may have been hit by a meteorite the entire size of the famous Meteor (Barringer) Crater in Arizona which is 1.2 kilometers wide. [Full Story]
a few of the previously known
Barringer's Meteor Crater
The Barringer's Meteor Crater which is near Winslow, Arizona, is one the worlds best known craters. It is estimated to have been created at least 50,000 years ago. The crater is named after 'Daniel Monroe Barringer' because he was the first to theorize that the depression was created by a meteor. He based his conclusion on the observation of the many minerals surrounding the impact. Nearly a mile wide, and 570 feet deep, it was originally thought to have been caused by an explosion of super heated steam resulting from volcanic activity that might have occurred far below the surface. But this was wrong. The absence of any volcanic rocks in the area, coupled with the discovery of 'meteoritic iron' in the crater rim, and finely pulverised silica, convinced Barringer it was an impact crater.
Aorounga Crater
A team of scientists believes they have discovered a chain of impact craters in the Central African country of Chad that suggests ancient Earth may have been hit by an asteroid or fragmented comet similar to the cometary fragments from Shoemaker-Levy 9 that slammed into Jupiter in 1994. Discovered using Spaceborne Radar images, scientists believe that this apparent string of impact craters date back about 360 million years, to a time when the Earth was undergoing a period of mass biological extinction. The most prominent of the craters, is called Aorounga South. It has been observed in (Landsat) satellite-based images and has been verified by ground work in 1992. The other two craters, Aorounga Central and Aorounga North, have not yet been scientifically confirmed through similar fieldwork.
Manicougan Crater
The Manicougan crater in Quebec, Canada, is believed to have been caused by an impact around 200 to 300 million years ago. At roughly 60 miles across, the Manicougan crater ranks as joint 5th largest crater in the world, along with the Popigai crater in Russia, which is about the same size. It has been thought previously that the impact which caused this crater was responsible for the Triassic-Jurassic extinction event, but scientists have pointed out that, at approx 214 million years old, this impact occurred well before what has become known as 'the TJ event'.
Kara-Kul Crater
Partially filled with the waters of the Kara-Kul Lake, this impact crater is estimated to be less than 10 million years old. It is located in the 'Pamir Mountain Range' of Tajikistan, close to the border with Afghanistan in central Asia. The crater is 28 miles in diameter, and the lake is 16 miles across. NASA's Johnson Space Center in Houston, Texas, has made available a collection of photographs of the Karakul crater taken by astronauts. You can access these at the website of the Astronaut Photography of Earth - Display Record. At around 20,000 feet above sea-level it is one of the highest impact craters in the world, and only recently has impact-shock features been found in local 'breccias' and 'cataclastic rocks'. As the country opens up to co-operation with Western scientists, more data will become available.
Clearwater Lakes Crater
The Clearwater Lakes craters are the only examples on Earth of a pair of impact craters that were formed simultaneously by two separate meteorite impacts. This shows that in the past our planet has suffered from at least one major 'multiple bombardment' of cometary debris from space. It has been estimated that these twin craters were formed some 290 million years ago and research scientist at the Geological Survey of Canada began studying craters 25 years ago on the Apollo program. Many more impact craters all over Canada have come to light since that time. Clearwater Lake East (left) has a raised central area covered with impact melts, and these form the circle of islands. The lake to the right is also fomred by an impact crater, but this one has a central peak that is submerged.
Bosumtwi Crater
The Bosumtwi crater in Ghana, West Africa, shown here partly obscured by clouds, has a rim diameter of 6.5 miles. It is estimated to be around 1.3 million years old, and is filled almost entirely by Lake Bosumtwi. Beginning January 2000, researchers from the University of Syracuse started to explore the 'crater lake' to gather data that would help them assess the changes that occur after a major impact by a meteorite or asteroid. Led by Professor Christopher Scholz, the expedition had one major objective, as explained by Prof. Scholtz: "Our data should provide information about what happens when an impact hits hard, pre-Cambrian, crystalline rocks that are a billion years old"
Mistastin Lake Crater
The view of this crater lake to the left was taken by astronauts aboard the Space Shuttle. The crater has been heavily eroded over time, especially by the eastward-moving glaciers, which have reduced the rim exposing the crater floor. The breccias have almost disappeared as a result. At the centre of the crater lake is 'Horseshoe Island', which is formed by the central uplift of the crater floor. This winter view shows the crater-lake, and the island at its centre, starkly contrasted against the snow. Scientists estimate the crater to be around 38 million years old, and the rim diameter is a little under 17.5 miles. Just beyond the margins of the lake are vestiges of the impact melt sheet that contains evidence of meteoritic features in quartz, feldspar and diaplectic glasses.
Wolfe Creek Crater
Discovered during an aerial survey in 1947, Wolfe Creek meteorite crater is just over half a mile wide - rim to rim. The crater is now thought to have been formed by a meteorite or asteroid impact around 300,000 years ago. It has been known by Aboriginal peoples as 'Kandimalal' for countless centuries, and Aboriginal Dreamtime lore tells of: " ... two rainbow snakes who formed the nearby Sturt and Wolfe Creeks as they crossed the desert. The crater is believed to be the place where one snake emerged from the ground." Now a protected reserve, Wolfe Creek was named in 1889 after Robert Wolfe, chairman of the Kimberley Goldfields Roads Board, a prospector and storekeeper of Halls Creek.
Tunguska airburst
Some incoming asteroids and cometary debris are of a mainly stoney composition. At 7:14 a.m. on 30 June 1908 a 'fireball' exploded about 5 miles above the Tunguska River valley in Siberia. For thousands of square miles around the area of the 'airburst' the trees were flattened. The force of the blast was equivalent to 1000 Hiroshima bombs. The heat incinerated herds of reindeer and burned tens of thousands of evergreen trees across eastern Siberia. For several days the sky was bright with an eerie orange glow that was seen for thousands of miles around. It was widely reported that as far away as western Europe people were able to read newspapers and books 'in the middle of the night' without using a lamp or candle. |
Below are some images of asteroids. Click on the images to go to the websites of orgin Asteroid Eros
"Several spacecraft have orbited or landed on asteroids and sent pictures of these bodies back to Earth. The NEAR Shoemaker mission, launched in 1996, was the first spacecraft to land on an asteroid, touching down on Eros on February 12, 2001."
Asteroid 253 Mathilde
On June 27, the NEAR (for Near Earth Asteroid Rendezvous) spacecraft, traveling some 36,000 kilometers per hour, streaked past an asteroid named Mathilde far beyond the orbit of Mars. It was just a brief encounter along a long journey to a different asteroid, Eros.
Asteroid Ida
"Liquid water, carbon-based molecules and a relatively stable environment are critical elements for life. Comets and asteroids can bring water and the chemicals on which life is based, but can also bring widespread destruction. If future impacts are inevitable, what should we do?"
Books About Asteroids, Comets, Meteor Storms, Impact Craters & Ancient Cosmic Catastrophes
New Books March 2008
"A Sumerian Observation of the Kofels' Impact Event" "Around 700 BC an Assyrian scribe in the Royal Place at Nineveh made a copy of one of the most important documents in the royal collection. Two and a half thousand years later it was found by Henry Layard in the remains of the palace library. It ended up in the British Museum's cuneiform clay tablet collection as catalogue No. K8538 (also called "the Planisphere"), where it has puzzled scholars for over a hundred and fifty years. In this monograph Bond and Hempsell provide the first comprehensive translation of the tablet, showing it to be a contemporary Sumerian observation of an Aten asteroid over a kilometre in diameter that impacted Kofels in Austria in the early morning of 29th June 3123 BC."
"The Chesapeake Bay Crater: "This volume synthesizes 16 years of geological and geophysical studies which document an 85-km-wide impact crater buried 500 m beneath Chesapeake Bay in south eastern Virginia, USA. The authors integrate extensive seismic reflection profiling and deep core drilling to analyze the structure, morphology, gravimetrics, sedimentology, petrology, geochemistry, and paleontology of this submarine structure. Of special interest are a detailed comparison with other terrestrial and extraterrestrial craters, as well as a conceptual model and computer simulation of the impact. The extensive illustrations encompass more than 150 line drawings and core photographs. An accompanying CD-ROM includes selected seismic profiles, scaled cross sections, detailed maps, and downhole geophysical logs."
"Bombarded Britain: A Search for British Impact Structures" "Describes a search for geological evidence of meteorite impact structures in Britain. The statistics of impact structures indicate that Britain should have Phanerozoic impact structures up to tens of kilometres in diameter. A constant theme is the importance of atmospheric break-up of small asteroids and comets. These fragmenting bodies produce anomalously shallow craters with low rims and central peaks; three British structures of this type are identified. Analysis of fireball statistics implies that damaging fireball explosions occur over the British Isles on a time-scale of decades. On a time-scale of millennia, however, more damage is done by Atlantic impact tsunami."
"The Big Splat, or How Our Moon Came to Be: A Violent "Mackenzie prefaces his absorbing account of the new "giant impact" theory of the moon's origin with the fascinating story of humanity's long relationship with Earth's only natural satellite. Evidence of that relationship begins with what is very probably a lunar calendar among the famous Lascaux cave paintings, and continues in early civilizations' timekeeping uses of the moon and classical Greek ideas about the moon's composition. In the fifth century B.C.E., Anaxagoras correctly realized that the moon was made of rock. Later, Aristotle didn't agree, and his view held sway for centuries."
"Impact Tectonics" "This volume is the 8th in a series of impact books resulting from the activities of the scientific program "Response of the Earth System to Impact Processes" (IMPACT), by the European Science Foundation. The book resulted from an international meeting at Mora, Sweden, which was held as part of the IMPACT program. The papers cover various structural geologic, geochemical, and geophysical topics on research of asteroid impact structures on Earth and Mars."
"The Cambridge Encyclopedia "In recent years, meteorites have caught the imagination of scientist and collector alike. An army of people are now actively searching for them in the hot and cold deserts of Earth. Fascinating extraterrestrial rocks in meteorites are our only contact with materials from beyond the Earth-Moon system."
"The Celtic Gods: "The Celtic myths, involving heroic warriors such as Finn and CuChulinn, can be read as simple primitive stories, but closer examination reveals strange descriptions and relationships. The authors of this ground-breaking book argue that all the principal characters are aspects of the one Celtic sky god, Lugh, who was a comet. Against the background of a comet scenario this re-interpretation of about ten key Celtic myths shows how many of the descriptions in the myths fit the appearance of comets. The fact that these comets on occasions produced abrupt environmental changes, that can be traced in the tree-ring and ice-core chronologies, pins the stories to a central reality. With a novel twist this original book confirms the widespread belief that these stories must contain a 'core of truth'."
"Rogue Asteroids and "Could both Stonehenge and the pyramids of Egypt have been constructed to observe and commemorate a period of phenomenal meteor storms and asteroid detonations produced by a burst of activity in the Taurid Complex 4,500 to 5,000 years ago? Author Duncan Steel examines the evidence indicating rogue asteroids and doomsday comets may have been behind these and other ancient phenomena."
"The End of the Dinosaurs: "The End of the Dinosaurs gives a detaile |
