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Post by Dave on Sept 10, 2012 19:46:41 GMT -5
Earth's Inconstant Magnetic Field12.29.03www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.html Our planet's magnetic field is in a constant state of change, say researchers who are beginning to understand how it behaves and why. Every few years, scientist Larry Newitt of the Geological Survey of Canada goes hunting. He grabs his gloves, parka, a fancy compass, hops on a plane and flies out over the Canadian arctic. Not much stirs among the scattered islands and sea ice, but Newitt's prey is there--always moving, shifting, elusive. His quarry is Earth's north magnetic pole. At the moment it's located in northern Canada, about 600 km from the nearest town: Resolute Bay, population 300, where a popular T-shirt reads "Resolute Bay isn't the end of the world, but you can see it from here." Newitt stops there for snacks and supplies--and refuge when the weather gets bad. "Which is often," he says. Right: The movement of Earth's north magnetic pole across the Canadian arctic, 1831--2001. Credit: Geological Survey of Canada. Scientists have long known that the magnetic pole moves. James Ross located the pole for the first time in 1831 after an exhausting arctic journey during which his ship got stuck in the ice for four years. No one returned until the next century. In 1904, Roald Amundsen found the pole again and discovered that it had moved--at least 50 km since the days of Ross. The pole kept going during the 20th century, north at an average speed of 10 km per year, lately accelerating "to 40 km per year," says Newitt. At this rate it will exit North America and reach Siberia in a few decades. Unless the rate of change increases!Keeping track of the north magnetic pole is Newitt's job. "We usually go out and check its location once every few years," he says. "We'll have to make more trips now that it is moving so quickly." Earth's magnetic field is changing in other ways, too: Compass needles in Africa, for instance, are drifting about 1 degree per decade. And globally the magnetic field has weakened 10% since the 19th century. When this was mentioned by researchers at a recent meeting of the American Geophysical Union, many newspapers carried the story. A typical headline: "Is Earth's magnetic field collapsing?" Probably not. As remarkable as these changes sound, "they're mild compared to what Earth's magnetic field has done in the past," says University of California professor Gary Glatzmaier. Sometimes the field completely flips. The north and the south poles swap places. Such reversals, recorded in the magnetism of ancient rocks, are unpredictable. They come at irregular intervals averaging about 300,000 years; the last one was 780,000 years ago. Are we overdue for another? No one knows. Remember - disagree with the method for determining ancient dates - time is not linear!According to Glatzmaier, the ongoing 10% decline doesn't mean that a reversal is imminent. "The field is increasing or decreasing all the time," he says. "We know this from studies of the paleomagnetic record." Earth's present-day magnetic field is, in fact, much stronger than normal. The dipole moment, a measure of the intensity of the magnetic field, is now 8 x 1022 amps x m2. That's twice the million-year average of 4 x 1022 amps x m2. Attachments:
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Post by Dave on Sept 10, 2012 20:15:08 GMT -5
Magnetic stripes around mid-ocean ridges reveal the history of Earth's magnetic field for millions of years. The study of Earth's past magnetism is called paleomagnetism. Image credit: USGS. The point I will make again deals with the matter of time. Time is not linear. These changes could have happened overnight! Attachments:
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Post by Dave on Sept 10, 2012 20:19:58 GMT -5
To understand what's happening, says Glatzmaier, we have to take a trip ... to the center of the Earth where the magnetic field is produced. At the heart of our planet lies a solid iron ball, about as hot as the surface of the sun. Researchers call it "the inner core." It's really a world within a world. The inner core is 70% as wide as the moon. It spins at its own rate, as much as 0.2o of longitude per year faster than the Earth above it, and it has its own ocean: a very deep layer of liquid iron known as "the outer core." Earth's magnetic field comes from this ocean of iron, which is an electrically conducting fluid in constant motion. Sitting atop the hot inner core, the liquid outer core seethes and roils like water in a pan on a hot stove. The outer core also has "hurricanes"--whirlpools powered by the Coriolis forces of Earth's rotation. These complex motions generate our planet's magnetism through a process called the dynamo effect. Attachments:
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Post by Dave on Sept 10, 2012 20:21:18 GMT -5
Using the equations of magnetohydrodynamics, a branch of physics dealing with conducting fluids and magnetic fields, Glatzmaier and colleague Paul Roberts have created a supercomputer model of Earth's interior. Their software heats the inner core, stirs the metallic ocean above it, then calculates the resulting magnetic field. They run their code for hundreds of thousands of simulated years and watch what happens. What they see mimics the real Earth: The magnetic field waxes and wanes, poles drift and, occasionally, flip. Change is normal, they've learned. And no wonder. The source of the field, the outer core, is itself seething, swirling, turbulent. "It's chaotic down there," notes Glatzmaier. The changes we detect on our planet's surface are a sign of that inner chaos. They've also learned what happens during a magnetic flip. Reversals take a few thousand years to complete, and during that time--contrary to popular belief--the magnetic field does not vanish. "It just gets more complicated," says Glatzmaier. Magnetic lines of force near Earth's surface become twisted and tangled, and magnetic poles pop up in unaccustomed places. A south magnetic pole might emerge over Africa, for instance, or a north pole over Tahiti. Weird. But it's still a planetary magnetic field, and it still protects us from space radiation and solar storms. Supercomputer models of Earth's magnetic field. On the left is a normal dipolar magnetic field, typical of the long years between polarity reversals. On the right is the sort of complicated magnetic field Earth has during the upheaval of a reversal. Attachments:
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Post by Dave on Sept 10, 2012 21:29:47 GMT -5
Ponder this:We have all played with small magnets. The magnets leap together if aligned properly - if not they repel each other with the same force. Consider if the median line of our galactic plane may also have some type of gravimetric / electromagnetic force of it own. Like a large magnet with one end pointing to the galactic core and the opposite end pointing off into space. Every 25-30,000 years the entire solar system crosses the galactic median plane. This might have several effect on all the planets of this solar system. 1. - planetary warming, the ice caps are melting on IO and Mars, as well as Earth 2. - the sun behaves erratically - and ours has 3. - the electromagnetic fields of the planets behave erratically (reference) - pole drift and sometimes pole-flip 4. - multiple forces tug and pull at the planets until their rotational wobble increases. 5. - Rotational mechanics and Angular Momentum demand that the masses of earth redistribute to re-balance the globe - meaning volcanoes and earthquakes. 6. - any change in the orientation between earth and sun - demand a change in weather pattern The consequences for the biospheres of each planet depend on the extremes of the planetary changes. Some galactic plane crossings my happen hardly noticeable - some destroy global cultures and changes the planet - resets the planet - for a new beginning or a new age. Attachments:
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Post by Dave on Sept 10, 2012 22:53:23 GMT -5
Scientist talk of a few thousand years. Some believe that 12/21/2012 is it! When actually it is a little of both. When? Look at the graph. This change is accelerating! There is no other explanation. Things are happening at an increased rate the closer and closer we approach the galactic plane. Coincidence? Edgar Casey spoke of the earth changes beginning in a period between 1958 and 1998. 40 years in the Wilderness comes to mind! He also spoke of 3 phases of change. Ponder this: 3 phases 40 years each. Phase 1 - 58-98 - slow, but progressive increase of earth events (earthquake, etc) Phase 2 - 1998 + 40 = 2038 - Catastrophic transition period Phase 3 - 2038-2078 - slow, but progressive decrease in earth events Now consider 12/21/2012 Phase 1 - 58-98 Phase 2 - 98 +14 = 2012 Phase 2 - 2012 + 7 = 2018 -- + 7 years of TRIBULATIONS = exactly 20yrs - the middle of the whole cycle - the collapse of Governments - Armageddon - mass lose of life Phase 3 - 2018 + 20 = 2038 -- and hardly any life remains BUT DAVE your math is wrong! 2012 + 7 = 2018and I say it is close enough to make a good Ponder Consider as well - the world government are spending like there is no tomorrow. They don't even seem concerned. I wonder what they really know. Perhaps they are that concerned for the future because they already know it is all going to fall away. Attachments:
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Post by Dave on Sept 16, 2012 12:53:18 GMT -5
Magnetic polar shifts causing massive global superstormswww.sott.net/articles/show/223364-The-Beginning-of-Ice-Age-Magnetic-polar-shifts-causing-massive-global-superstorms NASA has been warning about it...scientific papers have been written about it...geologists have seen its traces in rock strata and ice core samples... Now "it" is here: an unstoppable magnetic pole shift that has sped up and is causing life-threatening havoc with the world's weather. Forget about global warming - man-made or natural - what drives planetary weather patterns is the climate and what drives the climate is the sun's magnetosphere and its electromagnetic interaction with a planet's own magnetic field. When the field shifts, when it fluctuates, when it goes into flux and begins to become unstable anything can happen. And what normally happens is that all hell breaks loose. Magnetic polar shifts have occurred many times in Earth's history. It's happening again now to every planet in the solar system including Earth.
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Post by Dave on Sept 16, 2012 13:07:31 GMT -5
Reversals: Magnetic FlipBGS – British Geological Society, Geomagnatism www.geomag.bgs.ac.uk/education/reversals.htmlWhat do we mean by a magnetic reversal or a magnetic 'flip' of the Earth? The Earth has a magnetic field, as can be seen by using a magnetic compass. It is mainly generated in the very hot molten core of the planet and has probably existed throughout most of the Earth's lifetime. The magnetic field is largely that of a dipole, by which we mean that it has one North pole and one South pole. At these places, a compass needle will point straight down, or up, respectively. It is often described as being similar in nature to the field of a bar (e.g. fridge) magnet. However there is much small-scale variation in the Earth's field, which is quite different from that of a bar magnet. In any event, we can say that there are currently two poles observed on the surface of the Earth, one in the Northern hemisphere and one in the Southern hemisphere. By magnetic reversal, or 'flip', we mean the process by which the North pole is transformed into a South pole and the South pole becomes a North pole. Interestingly, the magnetic field may sometimes only undergo an 'excursion', rather than a reversal. Here, it suffers a large decrease in its overall strength, that is, the force that moves the compass needle. During an excursion the field does not reverse, but later regenerates itself with the same polarity, that is, North remains North and South remains South. How often do reversals occur?As a matter of geological record, the Earth's magnetic field has undergone numerous reversals of polarity. We can see this in the magnetic patterns found in volcanic rocks, especially those recovered from the ocean floors. In the last 10 million years, there have been, on average, 4 or 5 reversals per million years. At other times in Earth's history, for example during the Cretaceous era, there have been much longer periods when no reversals occurred. Reversals are not predictable and are certainly not periodic in nature. Hence we can only speak about the average reversal interval. (again - I will never get hung up about time lines of millions of years - time is not linear- it is a mistake to go forward still encoding timelines of millions of year as we once did)
Is the Earth's magnetic field reversing now? How do we know? Measurements have been made of the Earth's magnetic field more or less continuously since about 1840. Some measurements even go back to the 1500s, for example at Greenwich in London. If we look at the trend in the strength of the magnetic field over this time (for example the so-called 'dipole moment' shown in the graph below) we can see a downward trend. Indeed projecting this forward in time would suggest zero dipole moment in about 1500-1600 years time. This is one reason why some people believe the field may be in the early stages of a reversal. We also know from studies of the magnetisation of minerals in ancient clay pots that the Earth's magnetic field was approximately twice as strong in Roman times as it is now. Even so, the current strength of the magnetic field is as high as it has been in the last 50,000 years, even if it is nearly 800,000 years since the last reversal. Also, bearing in mind what we said about 'excursions' above, and knowing what we do about the properties of mathematical models of the magnetic field, it is far from clear we can easily extrapolate to 1500 years hence. Back to the top. How quickly do the poles 'flip'? We have no complete record of the history of any reversal, so any claims we can make are mostly on the basis of mathematical models of the field behaviour and partly on limited evidence from rocks that retain an imprint of the ancient magnetic field present when they were formed. For example, the mathematical simulations seem to suggest that a full reversal may take about one to several thousand years to complete. This is fast by geological standards but slow on a human time scale. What happens during a reversal? What do we see at the Earth's surface?As above, we have limited evidence from geological measurements about the patterns of change in the magnetic field during a reversal. We might expect to see, based on models of the field run on supercomputers, a far more complicated field pattern at the Earth's surface, with perhaps more than one North and South pole at any given time. We might also see the poles 'wandering' with time from their current positions towards and across the equator. The overall strength of the field, anywhere on the Earth, may be no more than a tenth of its strength now. Is there any danger to life?Almost certainly not. (OK - I feel better now. Guns don't kill people , people do. Tobacco don'y kill you, it is cancer's fault. AND the global famine isn't the magnetosphere problem, it the rain's fault) The Earth's magnetic field is contained within a region of space, known as the magnetosphere, by the action of the solar wind. The magnetosphere deflects many, but not all, of the high-energy particles that flow from the Sun in the solar wind and from other sources in the galaxy. Sometimes the Sun is particularly active, for example when there are many sunspots, and it may send clouds of high-energy particles in the direction of the Earth. During such solar 'flares' and 'coronal mass ejections', astronauts in Earth orbit may need extra shelter to avoid higher doses of radiation. Therefore we know that the Earth's magnetic field offers only some, rather than complete, resistance to particle radiation from space. Indeed high-energy particles can actually be accelerated within the magnetosphere. At the Earth's surface, the atmosphere acts as an extra blanket to stop all but the most energetic of the solar and galactic radiation. In the absence of a magnetic field, the atmosphere would still stop most of the radiation. Indeed the atmosphere shields us from high-energy radiation as effectively as a concrete layer some 13 feet thick. Human beings have been on the Earth for a number of million years, during which there have been many reversals, and there is no obvious correlation between human development and reversals. Similarly, reversal patterns do not match patterns in species extinction during geological history.
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