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Scientists have studied the way that Earth's magnetic field is generated deep within its core by conducting theoretical investigations, and advanced supercomputer modeling. The conclusion is that all objects that create their magnetic fields by flowing currents of matter deep inside, a process called the Dynamo Mechanism, will fall victim to these reversals over time.
In this activity, students will plot the changes in Earth's magnetic field during the last 800,000 years, and investigate the answers to some important questions about past magnetic variations and future magnetic reversals. This is a plot of the change in the main field strength of Earth for the last 800,000 years. Students will use tabulated data based on the figure above, and re-plot a version of the above graph. The data are based on the accumulated measurements by geologists from a variety of geological deposits, strata, and ocean sediment samples. The Magnetic Field Of Earth's Moon Used To Be Much Stronger, Researchers Are Baffled You are using an outdated browser. Benjamin Weiss, the co-author of the new study, says, “Earth’s magnetic field is currently 50 microteslas in strength. Grain bins much like these modern ones, photographed in southern Africa, were ritually burned down during Africa's Iron Age. Patches of ground where huts were burned down in southern Africa contain a key mineral that recorded the magnetic field at the time of each ritual burning. This depicts the lower strength of the Earth's protective magnetic field over the Southern Atlantic Anomaly, overlaid with the hot, dense mantle rock of an underlying feature deep below. Modern magnetic records only stretch back for the past 150 years or so, and within that time frame, researchers have seen the Earth's magnetic field rapidly decrease in intensity. Throughout that time, the inhabitants of ancient African villages would burn down the huts and grain bins in their villages on a regular basis, giving scientists key, consistent data throughout that time period. At the very least, it cleansed the ground: The burning villages would reach temperatures of over 1,800 degrees Fahrenheit (1,000 degrees Celsius), which would melt the magnetic compounds like magnetite in the clay floors.
Researchers had obtained very little historical data in the southern hemisphere, and none in southern Africa before these findings.
That feature is a section of particularly hot and dense mantle rock just above the Earth's outer core. During a reversal, the main field weakens, almost vanishes, then reappears with opposite polarity. A reversal could knock out power grids, hurt astronauts and satellites, widen atmospheric ozone holes, send polar auroras flashing to the equator and confuse birds, fish and migratory animals that rely on the steadiness of the magnetic field as a navigation aid. Although a total flip may be hundreds or thousands of years away, the rapid decline in magnetic strength is already damaging satellites. Last month, the European Space Agency approved the world's largest effort at tracking the field's shifts. The discipline is one of a number -- like high-energy physics and aspects of space science -- where Europeans have recently come from behind to seize the initiative, dismaying some American experts. Deep inside the Earth, the magnetic field arises as the fluid core oozes with hot currents of molten iron and this mechanical energy gets converted into electromagnetism. No one knows precisely why the field periodically reverses, but scientists say the responsibility probably lies with changes in the turbulent flows of molten iron, which they envision as similar to the churning gases that make up the clouds of Jupiter. In theory, a reversal could have major effects because over the ages many aspects of nature and society have come to rely on the field's steadiness. When baby loggerhead turtles embark on an 8,000-mile trek around the Atlantic, they use invisible magnetic clues to check their bearings.
On a planetary scale, the magnetic field helps shield the Earth from solar winds and storms of deadly particles. Among other things, the field's collapse, scientists say, could let in bursts of radiation, causing a variety of disruptions. Ultraviolet radiation, the short, invisible rays from the sun, can harm some life forms, depress crop yields and raise cancer rates, causing skin cancer and cataracts in humans. Like many of the Earth's invisible rhythms, the field reversals are typically slow, taking anywhere from 5,000 to 7,000 years to complete. Strong evidence of their reality first emerged in the 1950's and 1960's when scientists towing magnetic sensors behind ships found that the rocky seabed exhibited odd stripes of magnetization.
It turned out that continuous flows of seabed lava became alternately magnetized over the ages as the polarities of the Earth's field switched one way, then the other. Paleomagnetic studies showed that the Earth's field reversed every half million years or so, but in a fairly random way and with early patterns more chaotic. As scientists began to understand the importance of reversals in the planet's history, they examined the fossil record for evidence of damage to life. But no consensus ever formed on how the flips might have doomed some creatures and spared others, and some experts faulted the correlations as statistically insignificant.
Meanwhile, starting in the late 1970's, scientists began to find wide evidence that many animals relied on the Earth's magnetic field for navigation.
Investigators looking into the origin of the reversals got new clues in 1995 when scientists at the Los Alamos National Laboratory and the University of California at Los Angeles succeeded in making the first computer simulation of the geodynamo in action, including field reversals. The current collapse drew wide scientific attention on April 11, 2002, when Nature, the British journal, published a major paper that detailed its growing weakness. They found it by comparing readings made in 1979 and 1980 by the American Magsat satellite with measurements by the Danish Oersted satellite, launched in 1999 and still operating. The finding drew wide attention because the magnetic anomalies seemed consistent with what the computer simulations identified as the possible beginnings of a flip.
In an interview, he said that the field's southern spot was 30 percent weaker than elsewhere and that some satellites passing over it had already suffered electronic malfunctions when highly charged particles from the sun were able to penetrate the weakened magnetic shield. In March 2003, The Core, a Hollywood film, gave a wildly exaggerated portrayal of what would happen if the field vanished.
The consensus among biologists seems to be that the reversals are slow enough, and the Earth's creatures resilient enough, that most would learn to adapt.
To better understand the current collapse, the European Space Agency plans to launch three satellites in 2009. Does an Italian village filled with cigarette smoking centenarians hide the secret to long life? I am only a child playing on the beach, while vast oceans of truth lie undiscovered before me.

Convection currents flowing in the Earth's molten outer core due to ongoing radioactive decay generate a magnetic field. The Eartha€™s magnetic field showing field direction at both poles and either side of the magnetic equator.
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Use the form below to delete this Alberta Energy Exploring For Minerals image from our index. Use the form below to delete this Withlacoochee River Watershed Ground Water Pollution Potential To The image from our index. The Earth's magnetic field protects life on Earth, shielding it from damaging radiation and moderating our climate.
Gizmodo UK is part of Future plc, an international media group and leading digital publisher. The span of time between these reversal episodes depends on how fast the body is spinning, how large the body is, whether the body is solid or gaseous, and how electrically-conducting the material happens to be. The Brunhes-Matuyama Reversal ended 980,000 years ago when the polarity of the field actually did 'flip'.
They will then answer specific questions about the changes in Earth's magnetic field during the last 800,000 years. This data point is not included in the table below, but should be included in the student plots. The 'Time' columns indicate how many thousands of years before the present time the field was at the indicated strength.
The early moon may have had a magnetic field that was bigger, maybe up to more than 70 microteslas.”Weiss and Sonia Tikoo, who had their study published in Journal Sciences, suggest that the magnetic field of the moon can be the result of the molten liquid core that our satellite had taken for research. Those mineral records teach researchers more about a weird, weak patch of Earth's magnetic field called the South Atlantic Anomaly and point the way toward a possible mechanism for sudden reversals of the field. It may be the most dangerous place in the Earth's sphere for satellites and spacecraft to traverse, because anything electronic traveling through it is vulnerable to strong radiation from space and tends to malfunction. John Tarduno and other researchers think the irregularity below may cause the weakened field above. Such anomalies, in weakening the magnetic field, may bring the Earth closer to a magnetic reversal — when the magnetic north and south poles on Earth switch places, rearranging the magnetic field over the course of 1,000 to 10,000 years (although it can happen faster). But the researchers used the Iron Age remnants of African villages to extend their view even further back, from A.D. The magnetite would become remagnetized by the Earth's magnetic field at the precise instant it cooled, ready to be analyzed centuries later. The section is 1,860 miles (3,000 km) below southern Africa and the Atlantic, and it's about as wide as the distance between New York and Paris.
Her work has been featured by Scientific American, IEEE Spectrum, Quanta Magazine, Wired, The Scientist, Science Friday and WGBH's Inside NOVA. Afterward, compass needles that normally point north would point south, and during the thousands of years of transition, much in the heavens and Earth would go askew. But experts said the repercussions would fall short of catastrophic, despite a few proclamations of doom and sketchy evidence of past links between field reversals and species extinctions. A trio of new satellites, called Swarm, are to monitor the collapsing field with far greater precision than before and help scientists forecast its prospective state. Tarduno put the odds of an impending flip at more likely than not, adding that some of his colleagues were placing informal bets on the possibility but realized they would probably be long gone by the time the picture clarified. So do salmon and whales, honeybees and homing pigeons, frogs and Zambian mole rats, scientists have found. Its so-called magnetosphere extends out 37,000 miles from Earth's sunlit side and much farther behind the planet, forming a comet-like tail.
The seabed acted like a huge tape recorder, and the same proved true of the layered deposits of old volcanoes on land. Molten lava proved to hold tiny mineral grains that acted like innumerable compasses, or miniature magnets, freely aligning themselves with the contemporary field. Tarduno said that practical effects on things like satellites and the ozone layer would be the same no matter whether the field reversed or simply weakened and bounced back.

They note the lack of correlations in the fossil record between flips and mass extinctions. The spacecraft, flying in polar orbits a few hundred miles up, are to map its intricacies until perhaps 2015. Hulot said scientists would combine the satellite data with computer simulations to make not only distant forecasts but possible warnings of current hazards.
As this is only motion apparent from earth the observer is really saying the earth has altered motion! The poles of this magnetic field do not coincide with true North and South poles that coincide with the axis of rotation of the Earth.
So the idea that it could completely flip around, or collapse altogether, should cause us to worry, right? Since that time, the polarity of Earth's field has remained the same as what we measure today with the Northern Hemisphere Arctic Region containing a 'South-Type' magnetic polarity, and the Antarctic Region containing a 'North-type' polarity.
They postulate that planets  and other bodies move electrically conducting fluids around themselves, thus generating magnetic fields through a process which they compared to a dynamo. The process generally happens every 200,000 to 300,000 years, after the magnetic field weakens enough, but the last magnetic-field reversal occurred 780,000 years ago. The effect did not appear to be continuous, but rather seemed to be a recurring event in that part of the globe, whose weakening power comes and goes over time. During solar storms, objects passing through the anomaly are much more strongly affected by damaging cosmic rays.
Sarah has an MA from NYU's Science, Health and Environmental Reporting Program and an AB in mathematics from Brown University. The last one took place 780,000 years ago, when Homo erectus was still learning how to make stone tools. Jackman, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., has worked with European colleagues on a computer model that mimics the repercussions. Jackman said that the ozone damage from any one solar storm could heal naturally in two to three years but that the protective layer would stay vulnerable to new bursts of radiation as long as the Earth's magnetic field remained weak. But as the lava cooled, the tiny compasses froze in place, immobile even if the field shifted. Glatzmaier, who was one of the Los Alamos scientists, said it showed that the Earth's solid inner core resisted the flipping because the field there could not change as rapidly as it did in the fluid outer core.
Hulot and colleagues at the Institut de Physique du Globe de Paris, where he works, as well as the Danish Space Research Institute, called the large drop remarkable.
Hulot and his team discovered a north polar region and a spot below South Africa where the magnetism is growing extremely weak.
A major collapse of the Earth's magnetic shield, he added, could let speeding particles penetrate deeper into the atmosphere to widely knock out power grids, as solar storms do occasionally. Lohmann, a biologist at the University of North Carolina who has pioneered magnetic navigation studies in loggerhead turtles, said if the field became weak enough ''there would be problems for the turtles.'' His research suggests they use it not only for a general sense of direction but as a precise map of their location.
The solar magnetic field reverses with every sunspot cycle (11-years) while the solid Earth takes much longer (300,000 years or more). You will note that the last reversal ended when the magnetic intensity reached near-zero levels.
They note that earlier scientists did not understand whether the moon generated the magnetic filed itself or if it was due to the outside forces.The group of researchers spent the last six years using new and advanced search methods in order to find strong signals that the moon might have had a magnetic core of its own. 1,850 — and the record reveals that the South Atlantic Anomaly was going strong at that time, too.
When not writing, reading or thinking about space, Sarah enjoys musical theatre and mathematical papercraft. The field's strength has waned 10 to 15 percent, and the deterioration has accelerated of late, increasing debate over whether it portends a reversal of the lines of magnetic force that normally envelop the Earth. A weak field, they reported in December, could let solar storms pummel the atmosphere with enough radiation to destroy significant amounts of the ozone that protects the Earth from harmful ultraviolet light. Experts called it paleomagnetism and found that the tiny compasses were often made of magnetite, a naturally magnetic mineral. Hays of the Lamont-Doherty Earth Observatory of Columbia University noted a strong correlation between recent flips and species extinctions of tiny marine creatures known as radiolarians. Kirschvink of the California Institute of Technology discovered such reliance in bees, pigeons, bacteria, salmon, whales and newts, among other animals.
They believe that if the moon had a similar internal dynamo, it would allow them to better understand its inner structure and solve a problem scientists have grappled with for years.After several conducting studies, they could not say why the moon actually stopped producing the magnetic field. The magnetic sense, he found, usually relies on tiny crystals of magnetite -- the same mineral that gets immobilized in cooling lava. The Centre of the Earth The very heart of our planet is a solid inner core of mostly iron that is about the size of the moon.
Scientists do not know just how low our field has to fall in intensity before a reversal is triggered, but the threshold seems to be below 2.0 units on the scale of the above 'VADM' plot.
During samples collected from the Apollo missions, researchers claimed that the moon featured a magnetic field as strong as strong as 70 microteslas. Surrounding this solid inner core is a second layer made primarily of an iron-nickel alloy.
Electrical Currents The disparity in temperature between the inner core and the mantle causes the Earth to become a giant magnet.
As was recently explained: There needs to be a 2,700-degree F (1,500C) difference between the inner core and the mantle to spur "thermal movements" that a€“ along with Earth's spin a€“ create the magnetic field. As a stream of molten iron passes through the existing magnetic field [of the Sun], an electric current is generateda€¦ The newly created electric field will in turn create a magnetic fielda€¦   The Magnetic Field in Flux Given the fluidity of the system, it stands to reason that the magnetic field is not an immovable constant, but changes in its strength, orientation and polarity. To subscribe to Today I Found Out's "Daily Knowledge" newsletter,click here or like them on Facebook here.

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