The second system is the polar magnetic pole, which is a pair of points on the surface of the planet where the lines of force magnetic field goes into or out of the body in a position perpendicular to the planet's average surface (magnetic inclination 90). The point where the lines of magnetic force into the body of the planet is the magnetic north pole, opposite the point where the magnetic lines of force out of the body is the planet's south pole magnetically. However this nomenclature is not fully implemented, because in practice the magnetic poles of the name refers to the name of the geographic poles adjacent. Both magnetic poles can be likened to a pair of different ends of a giant bar magnet embedded in the body of the planet, although this assumption is not entirely correct. Magnetic poles is only concerned with the magnetic properties of celestial bodies, is not the nature of the rotation.
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| Figure 1. Overview geomagnetic lines of force and the axis magnetisnya. Notice the difference with the axis of rotation of the Earth and the existence of the geographic poles. Sources: NASA, 2009. |
position
On Earth, the magnetic north pole is located on the shores of the Arctic Ocean while the south magnetic pole is located at the edge of the Antarctic mainland. The position of the magnetic north pole not coincide with the geographic north pole is the case with a magnetic south pole geographic south pole. Ketakberimpitan makes compass needles (which always leads to the magnetic north pole) always form a certain angle to the direction of true north. This angle is known as magnetic declination, whose value varies for each point on the face of the Earth. When explored further, geomagnetic axis (ie, a straight line connecting the north-south magnetic pole in the body of the Earth) does not coincide with the axis of rotation of the Earth, but rather at an angle of 11.5 degrees. On the other hand, the geomagnetic axis itself was not symmetric, so that the position of the south magnetic pole is not exactly in the projection of a point-to magnetisnya north pole, but odds distances up to 2,700 km.
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| Figure 2. The position of the south magnetic pole of the Earth compared to the actual projection (point-opponent) magnetic north pole, which appears to be coincident. Ketidakberimpitan shows asymmetry in geomagnetic. |
Ketidakberimpitan and asymmetry of this kind is reasonable in our solar system, the Earth is not only experienced alone. Jupiter's magnetic axis is also at an angle to the axis of rotation, which is equal to 10 degrees. Even in Uranus and Neptune the situation is quite spectacular because magnetisnya each axis forming an angle of 59 degrees and 47 degrees to the axis of rotation. Instead Saturn magnetic axis almost coincides with the rotational axis where the angle between them is less than 0.5 degrees.
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| Figure 3. Comparison of Earth's axis of rotation and magnetic (left) with the axis of rotation and magnetic Uranus (right). Note that neither the magnetic axis coincides with the axis of rotation. Sources: NASA, 1986. |
generator
Why is this so? On Earth, the Earth's magnetic field (geomagnetic) generated by the convective flow of ions iron and other metals in the liquid outer core that are very thick. The convective flow is powered by internal heat of the Earth as a result of radioactive decay of heavy nuclei (uranium and thorium) and the rest of Earth's ancient heat of formation under the influence of Earth's rotation. Ion flow is essentially a stream of electrically charged particles, so that the equivalent electricity. Then Berlakulah combination circuit law Ampere, Faraday's law and the Lorentz force in the form of a dynamo mechanism with the end product is very large geomagnetic the structure. Not berimpitnya magnetic axis and the axis of rotation of the Earth is due to the internal dynamics of the Earth's core that lead to differences in rotational speed between the surface of the Earth's core.
A similar mechanism was also established another planet's magnetic field. It's just on Uranus and Neptune, the ions flow in the outer core is light ions (water, ammonia and methane) with the thickness of the convective layer that is thinner so that the axis of the magnetic field can form an extreme angle to the axis of rotation.
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| Figure 4. Shift in the position of the magnetic north pole point (left) and south (right) from year to year. Sources: NOAA, 2012. |
Internal dynamics of the Earth's core causes geomagnetic has amazing dynamics. One is the phenomenon of reversal of magnetic poles (magnetic reversal). Known magnetic poles do not occupy the same location for a long time, but always shifted at a certain speed. Since it was first identified two centuries ago, the north magnetic pole has shifted so far over 600 km with an average speed of 40 km / year. So that the magnetic north pole is reaching the geographic North Pole, although they would not coincide. The mathematical model shows the position of the magnetic north pole in the Arctic Ocean is now part of Canada would be shifted in such a way that in the next century will be entered Siberia (Russia).
Reversal and Destruction
In the long run, shifting magnetic poles will cause the exchange of positions which are now the magnetic north pole shifted such that someday occupy the location of the south magnetic pole and vice versa. The phenomenon of magnetic reversal of the poles is relatively frequent. Throughout the last 5 million years of Earth's magnetic pole reversals occur on average every 0.2 to 0.3 million years. But throughout the last half billion years, variations in Earth's magnetic pole reversal periodicity has a span of 5,000 years by 50 million years. Each magnetic reversal lasted for thousands of years so it is not a sudden event in the blink of an eye. Magnetic reversal can also take place due to external causes, for example due to hit the asteroid / comet giant to Earth.
Earth's magnetic pole reversal events of the latter, which is called the Brunhes-Matuyama event, occurred at 0.78 million years ago. At the present time, although the magnetic poles continue to shift, there are no signs of going to the next Earth magnetic pole reversal.
Despite the reversal of the magnetic poles, the lines of force of geomagnetic not disappear. Similarly, the deepest layer of the magnetosphere and its known as the van Allen radiation belts. So different from the common perception, in the event of reversal of the magnetic poles of Earth, the planet is still magnetosfernya protected from external threats in the form of galactic cosmic rays and solar particle radiation. This protection is so effective that when we refer to an abundance of living creatures along the curve half-billion last year, none of Earth's magnetic pole reversal events that coincided with the mass extinction (reduction of populations of living things suddenly and significantly) both major and minor, except by reason externally in such a collision the asteroid / comet.
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| Figure 5. Reversal dynamics of solar magnetic poles during the last 30 years (until mid 2012) following the solar activity cycle. It appears how the geographic north pole (latitude 90N) are alternated occupied by the magnetic north pole (Nm) and the magnetic south pole (Sm) Sun. Even though the geographic south pole. Sources: NASA, 2012. |
sun
Magnetic pole reversal is not a typical event Earth, but also occur in celestial bodies in the solar system other. Planets have magnetic fields also indicated experience. Even the sun too. Satellite observations Mataharis ecara observers consistently since the early 1980s from Uhuru, Solar Max to SOHO shows a magnetic pole reversal takes place more frequently with the Sun following the pattern of the solar activity cycle, ie an average of once every 11 years. And every time the sun magnetic reversal occurs, followed by activities outside the normal with the exception of an increase in the potential of solar storms are still quite reasonable.
So the rumors of the Earth magnetic pole reversal will occur and trigger the Apocalypse 2012 heralded long as this is going to collide with three scientific facts. First, so far no symptoms would be the occurrence of the event Earth's magnetic pole reversal. Second, the Earth's magnetic pole reversal activity is not a spontaneous event that occurred in the blink of an eye, but it took thousands of years. Third, take the analogy activity and solar magnetic pole reversal and data genocide, in the past the Earth magnetic pole reversal events are normal events that often occur and are not accompanied by devastating disasters that make reducing drastically reduced populations of living things.
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