The earth has a magnetic field surrounding it called the "geomagnetic field". The geomagnetic field of the earth is very similar to the field of a bar magnetic and has played a major part in navigation over the centuries. By using a compass needle which aligns itself with the magnetic poles of the earth, navigators were able to determine which direction was North and which was South. The magnetic poles of the earth are however not completely aligned with the geographic north and south poles and when navigating this has to be taken into consideration. Also at the present time the north pole of the geomagnetic lies in the southern hemisphere and the south pole of the geomagnetic lies in the northern hemisphere. The poles of the geomagnetic are presently oppositely orientated compared to each hemisphere.
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The earths core is made of molten metal such as iron or nickel. Iron
and nickel are very good conductors of electricity and electric
currents can flow easily in them. As the earth rotates large electric
currents are built up and these produce the earths magnetic field.
Earths geomagnetic field reverses direction every 70,000 years ! In 70,000 years the poles of the geomagnet will flip and the northerm hemisphere will be magnetic north and the southern hemisphere magnetic south. Following another 70,000 years the poles will again flip to be as they are now. It is still a mystery why this occurs!
Do you know that some animals such as pigeons or bottle nose dolphins can naturally use the earth magnetic field to navigate. That is why a pigeons can always find its way home!
As well has helping us with navigation, the earths geomagnetic field also protects us from the high speed solar wind that comes from the sun. The magnetic field provides an invisible barrier to the charged particles that stream towards us since the magnetic fields is able to reflect the charged particles. Without the magnetic field the earth would not be a nice place to live. When astronoughts travel ouside the earths magnetic field they need to wear special clothing to keep them safe from the solar wind.
As well as the earth having a magnetic field the sun also has a magnetic field. The suns magnetic field is however much more power than the earths and is also very different from the earths. The suns magnetic field can be found in strong concentrations called sunspots.
While at most the earths magnetic field is of size 0.7G the suns magnetic field in sunspots can be as much as 3000G! The magnetic field of the sun causes many of the objects that we see in the suns atmosphere. Click here to find out more about the sun magnetic field.
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