In this book Clive Ruggles is the first to approach the subject from the perspectives of both disciplines. He analyzes the history and lessons of previous debates, the most current research, and new agendas for future research. Get This Book From: Amazon. During fieldwork and research from to , Freeman found striking similarities between the surface geometry of the two sites. These similarities push back the boundaries of written history and have far-reaching implications for North American and European history. Passion and science blend in this remarkable, readable book, as Freeman takes us along on his patient and exciting discovery of a year-old Temple in the plains of Alberta.
What he finds at the Majorville Medicine Wheel in turn informs his convincing account of Stonehenge archaeoastronomy". Theories that many ancient megalithic sites began life as some form of observatories acting as 'early-warning systems' for imminent impacts of cosmic debris from the break up of a giant comet are only just beginning October to get a wider hearing. Such theories, if proven, could help not only to date these monuments, but illustrate how well their builders were oriented in time and space.
The simple appreciation that the Earth orbited the Sun and periodically passes through trails or streams of cosmic debris suggests that some ancient peoples could well have been far more aware of the position of the Earth in the solar system, and the dynamics of the solar system, than has previously been suspected. Should this prove to be the case, then it would seem that ancient peoples were far more aware of this than are most peoples today.
Duncan Steel , then of Spaceguard Australia , presented a paper to the Society for Inter-Disciplinary Studies conference at Fitzwilliam College, Cambridge, in July of , in which he gave details of his research suggesting that the earlier 'henge circle' which preceded the stone circles at Stonehenge, could have been deliberately constructed to function as a 'cosmic impact early warning system'.
The Cambridge conference itself focussed on the effects of natural catastrophes resulting from the impacts of cometary debris as being the main reasons for the sudden destruction of various Bronze Age civilisations. The Sunday Times of London reported on December 14th.
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The newspaper also gave an outline of the extensive work done by Oxford University astrophysicist, Victor Clube, who has been researching a meteor cluster in orbit around Jupiter, which he says:. Both Steel and Clube agree about the cosmic origins of the cataclysms that happened around BC, and The Sunday Times article explained that the meteor which exploded over Siberia in June had:.
In the 's and 's, Immanuel Velikovsky wrote of cosmic impacts in his books "Worlds in Collision" and "Earth in Upheaval".
Indeed he is credited with setting many modern skywatchers off on a path that has seen a rapid increase in travellers in the past thirty years or so, and though many of his ideas are treated with derision by the academic community, the seminal influence of his pioneering theories are undeniable - his books began a prehistory debate which is still 'very hot', and getting hotter still at the start of the 21st century. The study of Near Earth Objects NEOs is becoming one of the most exciting areas of modern astronomy, and as the science progresses, historical writings and the myths and legends of prehistoric times are being looked at again in a new light.
The current focus on re-interpreting ancient myths about battles between 'sky gods', 'dragons breathing fire', and 'thunderbolts from heaven', as containing the accurate observations of ancient skywatchers, is much in the same vein as the pioneering work of Owen Morien Morgan, who decoded the druidic folklore of the South Wales valleys, revealing the druidic oral traditions that symbolically depicted the constant interplay between the Sun, Moon, Earth and planets throughout course of the natural year.
It is becoming evident October that ancient peoples have, throughout the past several thousands of years, migrated away from areas devastated by periodic bombardments of cometary debris. These hurried migrations of refugee survivors were likely due not only to the destruction of centres of civilisation, but also as a result of the "Cosmic Winter" caused by the cometary dust-loading of the upper atmosphere which gave rise to abrupt climatic changes - rapid drops in temperature that undermined the agricultural base sustaining those societies. The BSCC that has emerged over the past twenty years is being taken ever more seriously by the military, by various governments , and by other scientists.
The Rome-based International Spaceguard Foundation is the leading body in the study of planetary defence against impacts of NEOs, but there are other organisations such as the Spaceguard Australia, Spaceguard Canada, as well as NASA, the European Space Agency, and the many universities that also have rapidly growing 'spacewatch' projects. They produce a newsletter, "Impact", containing up to date news about the threat of collisions with Near Earth Objects such as meteors, asteroids and comets, and focusses on efforts to set up an international system of 'planetary defence'.
Observed from an appropriate place in that locality, these simple structures could have served as accurate 'early warning systems' for ancient peoples who were seeing a much more active sky in terms of meteor showers and storms than we see today. Only the 'back-sight' needs to be located for this, and aerial photographs and fieldwork could identify them - should they exist. If found they could enhance our understanding of the practical usage of these pairs of standing stones in ancient times.
Of course there are many more astronomical events that ancient peoples may well have wanted to observe, but life-critical advance warning of imminent bombardments by cometary debris would be hard to top in any list of priorities by any people in any age. Some ancient megalithic monuments have been referred to as burial chambers because evidence of burials have been discovered in many of these types of monuments. Some of these burials have not been of humans, but of animals, specifically bulls and less frequently of cows.
Others have been shown to have the remains of human skeletons in their chambers, but these burials could well have occurred at a much later date than their construction, and it is now believed that one of their primary purposes may well have been as observatories for particular celestial events. The burial of bulls may also have been of a relatively late date compared to the dates of the construction of these stone chambers, which would have acted as 'telescope-type' chambers inasmuch as they would allow for the fainter stars to be observed at night.
And, more importantly, they would have allowed for accurate observation of the 'heliacal rising' of specific stars in the final half- hour or so before actual sunrise. As the major meteor storms of the Bronze Age and before were those that appeared to emanate from the constellation of Taurus the Bull , then it must be considered that the 'bull burials' which have been found in various ancient structures all over the world could well have been the result of an apparent widespread practice of 'sacrifices' to appease the anger of various 'gods'.
In ancient oral traditions, this 'anger' was almost always shown by the sending of 'thunderbolts' and the like, which are recorded in the mythologies and oral traditions of almost every ancient culture in all corners of the globe. Could these sacrifces have been of bulls because of the Taurid Meteors Storms that had caused such widespread death and destruction throughout antiquity? And, how far back did this go? It must also be remembered that the stars of the constellation of Taurus were observed in much more ancient times as well, and there are many depictions of bulls and 'bulls heads' found in caves once used by ancient peoples for both basic shelter from the elements as well as for a wide variety of 'ritual' purposes.
Did the'elements' from which ancient peoples sheltered in archaic times also include regular periods of 'bombardment' of cometary debris resulting from the break up of a giant comet, encounters with the fragments of which have caused chaos on our fragile planet for countless millennia throughout antiquity? Then as now, the rising of the constellation Taurus was preceded by the group of stars known as 'The Pleiades', which would have acted as'marker stars' for the imminent appearance above the horizon of the point, or 'radiant', from which the universally-dreaded Taurid meteors would have seemed to originate.
There are two annual episodes of Taurid Meteor Showers still 'observable' today, though over the preceeding millennia they have been greatly depleted, and what we see today is a just a pale reflection of some of the 'meteor storms' produced by this complex of cometary debris in ancient times. Our planet encounters the beta Taurid Complex between June 24 and July 6 each year, and it takes the Earth about 12 days to pass through these streams.
The second annual encounter is generally between November 3rd and the 15th each year, when they can be seen with the naked eye as 'shooting-stars' in the night sky appearing to emanate from the areas of the constellations of Taurus and Aries.
With the stars of the constellation of Taurus in the background behind the Sun in May and June, the meteors appear to come directly out of the Sun. They would not actually be 'seen until larger meteoroids particles of cometary debris came right through the upper atmosphere and impacted the Earth, or burst in the atmosphere a few miles above the ground, as did the widely reported 'fireball' of the Tunguska air-burst on June 30th This event is believed to have been the result of a large, stoney chunk of cometary debris from the Taurid Complex exploding with the force of Hiroshima bombs about 5 miles above the Tunguska River valley.
How often had this happened in the past? Was there much more debris up there in denser concentrations in the past? Or does our planet simply encounter the denser debris clouds in periods of approx. Having pondered on this question for several years, once one stops thinking in terms of modern scientific solutions the simple answer becomes as clear as daylight - controlled daylight that is. From inside the ancient stone chambers looking out, it would have been possible to see the stars, planets and any other celestial phenomena that passed within the 'window' provided by the chambers' entrances.
Even citizen scientists can participate in sample return missions. Most meteorites are chunks of asteroids that fall to Earth. In fact, several thousand tons of these space rocks and dust fall to our planet every day. Most burn up harmlessly in the atmosphere, but some make it to the ground without being vaporized. Scientists collect meteorites to study their structure and chemical composition.
From such studies we have learned a great deal about the different kinds of asteroids — for instance, there are three main types. Some asteroids are mostly metal, consisting of nickel and iron, like Earth's core. Others are a combination of these metals and rocky minerals, like magnesium and silicon. A third type of asteroid, the most common by far, is very dark and rich in carbon and has about the same composition as the Sun, minus hydrogen, helium and other easily evaporated chemicals.
This composition of this meteorite suggests it is a fragment of the asteroid Vesta, blasted off that small world by an impact long ago. Credit: R. Kempton New England Meteoritical Services.
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By determining the composition of Vesta from the way it reflects sunlight, scientist know it is the only large asteroid whose 'light signature' matches the basaltic rock of HED meteorites, those composed of the howardites, eucrites and diogenites. These basaltic meteorites from Mars were found in California's Mojave Desert. A 1-cm cube is shown for size comparison. Credit: Ron Baalke. Not all meteorites come from asteroids, however. Some are actually pieces of the Moon and Mars that were blasted off those worlds by powerful impacts.
Wherever they are from, meteorites are amazing — they give us actual samples of other worlds to study. And the best part is that they come to us! This iron meteorite was found in Antarctica. This sample is made of mainly iron and nickel and is probably a small piece from the core of a large asteroid that broke apart.
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It is easiest to spot meteorites in sandy desert regions, like Namibia in Africa, or permanently snow-covered places in Antarctica. In these areas, dark rocks stand out against the light-colored sand or white snow. Scientists look for meteorites in Antarctica, where the dark rocks from space are easy to see against the icy ground. People may someday visit asteroids and comets themselves, to perform detailed scientific studies or to look for natural resources. By then, he said, new spacecraft designed for long journeys could allow us to begin the first ever crewed missions beyond the Moon into deep space.
When humans finally travel to these primitive bodies, they will rely on the large body of knowledge collected by all the other types of exploration that paved the way. Exciting missions to explore these places begin with our desire to know about how the solar system formed, how it is still evolving today and how the story of life on Earth fits into that picture. The small worlds tell us about the conditions that prevailed when the Sun and planets were still forming. Call them "original members" of the solar system. Comets are the leftover building blocks of the outer planets, while asteroids are the remnants of the process that built the inner planets.
Both likely played important roles in the development of life on Earth as well. So if we are to understand the story of our origins, we must explore these primitive small bodies. And since a comet or asteroid impact could still pose a threat to our civilization, it is prudent for us to learn more about them. The groundbreaking missions of NASA's Discovery Program provide an excellent way for us to reach out to the small worlds, getting up close and getting to know them as real places. Each innovative new exploration has a unique focus, doing something that's never been done before.
Every mission adds more pieces of knowledge to help solve the expanding cosmic puzzle, while raising exciting new questions that beckon future explorers to venture out into the solar system. These missions teach us there are always surprises, changes to long-held beliefs, and new wonders to behold. Where are these missions going and what are we learning from them? The NEAR spacecraft was the first to perform a comprehensive study of an asteroid, spending one year in orbit around asteroid Eros. The mission had three main scientific goals: determine the physical and geological properties of a near-Earth asteroid; clarify relationships between asteroids, comets and meteorites; and further our understanding of how and under what conditions the planets formed and evolved.
NEAR produced our first detailed, global map of an asteroid. The mission revealed bizarre and surprising. These four images show the boulder-strewn surface of Eros at increasing resolution, just days before landing. The top images are from 8. The top scenes are about 1, feet across.
The bottom images were taken from 3 miles above the surface, showing feet across. Scientists were puzzled by the lack of small craters and the profound number of boulders they saw. Later analysis showed that most of the boulders were produced by the impact that created the asteroid's largest impact crater.
NEAR also showed that the composition of Eros is very similar to the meteorites called chondrites, but there was a discrepancy. The abundance of the element sulfur was less than in chondrites. However, NEAR's data tell us only about the thin, uppermost layer of the surface. A future mission to sample the asteroid could tell if the sulfur is depleted from only a thin surface layer or throughout the asteroid.
The NEAR team devised a spectacular finish to the yearlong orbit at Eros — the first-ever spacecraft landing on an asteroid. On February 12, , NEAR made a gentle landing on the tips of two solar panels and the bottom edge of its body. Then, to much amazement, the craft continued to operate and send signals back to Earth. For two weeks the team gathered the first scientific readings from an asteroid's surface, adding to the legacy of a mission that collected 10 times more data than planned and advanced the field of asteroid studies tremendously.
Dawn will orbit the large asteroid Vesta and the dwarf planet Ceres, two very different objects. Vesta is dry, differentiated, and shows signs of resurfacing. It resembles the rocky bodies of the inner solar system. Ceres has a primitive surface containing water-bearing minerals and has many similarities to the large icy moons of the outer solar system. By observing them both with the same set of instruments, Dawn can compare their different evolutionary paths.
Dawn will arrive at Vesta in and Ceres in Dawn is the first spacecraft to orbit an object, study it, and then re-embark under powered flight to a second target. All previous multi-target missions were planetary flybys. Dawn's ion propulsion engines make its unique journey possible. Dawn has the potential for making many paradigm-shifting discoveries. Ceres could have active processes leading to seasonal polar caps of water frost.
Vesta may have rocks more strongly magnetized than on Mars, altering our ideas of how and when magnetic fields arise on planets, and with important lessons for Mars, Earth and Mercury. Ceres might have a thin, permanent atmosphere distinguishing it from the other minor planets. The three big scientific drivers for the mission are first that it captures the earliest time in the origin of the solar system, enabling us to understand the conditions under which these objects formed.
Second, Dawn determines the nature of the building blocks from which the inner, terrestrial planets formed, improving our understanding of this formation. Finally, it contrasts the formation and evolution of two small worlds that followed very different evolutionary paths — helping us understand what controls that evolution. What we learn from Dawn will tell us volumes about not just these small worlds, but also about our own planet and its origins.
The Stardust spacecraft flew through the cloud of dust that surrounds the nucleus of comet Wild 2 in January The particles of cometary material and interstellar dust gathered were returned to Earth aboard a sample return capsule which landed in the Utah desert in January In the still-healthy spacecraft was retargeted to head for comet Tempel 1 on a new mission called Stardust-NExT. One of the most exciting findings from Stardust was the presence of organic materials — chemicals that are important to living things on Earth — in the comet dust.
Scientists found simple hydrocarbons, as well as the amino acid glycine, in samples from Wild 2. Hydrocarbons are used for energy by life on Earth, and amino acids are used to build proteins. These discoveries support the idea that the fundamental building blocks of life are common in space, meaning life may not be a rarity.
A surprising finding from the Stardust samples was the presence of minerals that came from the inner part of the young solar system, which has temperatures much warmer than the icy region where comets form. Many scientists expected that a lot of the dust in comets would be of interstellar origin, meaning it formed around other stars.
But most of the dust Stardust collected from Wild 2 contains minerals that formed in the presence of high heat, meaning they had to have condensed in the inner solar system close to the Sun and been blown out to the cold comet forming region beyond Pluto to be incorporated in the icy matrix of the comet. So it turns out that, rather than containing a nearly pristine record of the primitive interstellar material that originally formed our Sun and its planets, Wild 2 is a time capsule containing a diverse mixture of materials from locations all over the young solar system.
One of the big mysteries of Wild 2 is why it looks so dramatically different than the four other comets that have been imaged by a spacecraft. Most of the others are relatively smooth, but this one is dramatic with its really deep impressions, vertical cliffs, and spires sticking up into space. It has no impact craters which indicates its original surface has been lost and replaced by an incredibly rugged, intriguing surface.
It has depressions that look like the material has just collapsed, as a result of a very weak structure. It has no surface ices. Wild 2 showed us that the cometary nuclei are quite different from one another. This sequence of images depicts the development of the ejecta plume after impact.
The red arrows highlight shadows due to opacity of the ejecta. Deep Impact provided the first look at what is inside a comet. In July of , the spacecraft released a small, pound copper impactor directly into the path of comet Tempel 1. With a closing speed of about 22, miles per hour, the resulting collision produced an impact crater on the surface of the comet's nucleus. The impact and the 10, tons of material thrown out of the forming crater were observed in detail by the flyby spacecraft. The bright plume contained far more dust than scientists expected — one of the many surprises that makes science so exciting.
Analysis of the comet's outbursts of gas and dust revealed that the outbursts are not random events; instead, they are caused by active regions rotating into sunlight. Deep Impact showed that there is very little compositional variation with depth in the nucleus. Scientists found there is a tremendous amount of layering, some of which is thought to be primordial. Integrating the results from the mission, Principal Investigator Mike A'Hearn developed a new theory of cometary formation whereby low velocity impacts early in the history of the solar system produced "cometessimals" in the Kuiper belt that grew into comets by building up layer upon layer.
At low velocities, the material "splats" upon impact. A'Hearn calls the layers talps "splat" spelled backwards. This photo of Hartley 2 shows the carbon dioxide, dust, and ice apparently coming from the same area on the nucleus. The water vapor has a different distribution, implying a different source region and process. The EPOXI mission recycles the already in flight Deep Impact spacecraft for a new mission comprised of two projects with different scientific objectives.
EPO Ch, or Extrasolar Planet Observation and Characterization, observed stars with known transiting giant planets to characterize those planets and to search for others. One goal of the mission is to compare a small active comet with the larger inactive comets previous seen up close by spacecraft to get a better understanding of what features are due to evolution and which are a result of recent processing.
In , EPOCh observed seven stars with "transiting extrasolar planets" and also searched for evidence of rings and moons associated with the known giant planets of the targeted stars. In addition, the spacecraft paved the way for future observations of Earth-size extrasolar planets by taking a special set of observations of our own planet. The results of this work reveal how an image in which a planet fills only a single pixel could be used to infer the presence of oceans and continents like those on our home world.
The DIXI flyby of comet Hartley 2 captured spectacular images of this small, peanut-shaped active comet. The images show bright plumes of material spewing from the surface and are clear enough for scientists to link jets of dust and gas with specific surface features. The photos reveal a cometary snow storm created by carbon dioxide jets spewing out tons of golf-ball to basketball-sized fluffy ice particles from the comet's rocky ends. Stereo images reveal snowballs in front of and behind the nucleus, making it look like a scene from a snow globe.
At the same time, a different process caused water vapor to escape from the comet's smooth mid-section. The smooth area of comet Hartley 2 looks and behaves like most of the surface of comet Tempel 1, with water evaporating below the surface and percolating out through the dust. Carbon dioxide appears to be a key to understanding Hartley 2. This information sheds new light on the nature of comets and even planets, showing that Hartley 2 acts differently than the four other comet nuclei that have been imaged by spacecraft. The finding that carbon dioxide is powering the many jets could only have been made by traveling to a comet, because ground based telescopes can't detect CO2 and current space telescopes aren't tuned to look for this gas.
This image from the Deep Impact mission shows layering on Tempel 1, which provides clues to accretion during its formation or subsequent processing. The Stardust-NExT spacecraft will obtain new measurements of the comets features.
In February the Stardust spacecraft will take a new look at Tempel 1, adding much more to the wealth of discoveries scientists made from the Deep Impact experiment. Tempel 1 has completed a trip around the Sun since Deep Impact visited in , and this close pass through the inner solar system could have caused changes on the comet's surface. The Stardust-NExT mission will capture up-to-date images of the comet's surface, revealing what's new since Many hope it will finally give us a view of the crater that was created by Deep Impact but not visible at the time because of all the dust that was stirred up.
This will be the first time a comet has been visited by two different spacecraft, giving us a much deeper understanding of processes that affect the formation and evolution of these ancient building blocks of the solar system. Mike is a professor of astronomy at the University of Maryland. His distinguished career includes many contributions to the field of cometary science, including developing observational techniques to study their structure and composition. Previously, she was a research professor at the University of Maryland.
Small Worlds Big Questions. Getting to Know the Neighborhood. Why We Explore. Keys to the Past The small worlds of our solar system conceal answers to some of the most pressing questions about our own origins. Resources for the Future We also explore small worlds to understand the hazards and resources in the solar system that will affect human expansion in space. Protection from Potential Impacts Impacts are a process in the solar system that are capable of ending life as well as advancing it.
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How We Explore. Getting Up Close With Spacecraft Many spacecraft have visited comets and asteroids, and our capabilities to explore these bodies continue to increase. Some missions fly past small bodies on their way to other destinations, allowing us an exciting, quick glimpse of a comet or asteroid. From simple flybys we have progressed to orbiting these objects over a period of time, touching down on their surfaces, collecting samples to return to Earth, and even punching craters into them to examine what's inside.
Spacecraft allow us to carefully choose a set of tools with which to examine the small bodies of our solar system. As technology continues to improve, we can fly missions to answer specific questions about these intriguing little worlds. The Stardust mission collected tiny particles from the halo of dust and ice that surrounds comet Wild 2 and returned them to Earth where scientists are analyzing them and making amazing new discoveries.