The Earth's magnetic field

The earth’s magnetic field

The earth’s magnetic field is the magnetic field that surrounds the earth. It is often called the geomagnetic field.

The Earth’s magnetic field is created by the rotation of the Earth and earth's core. It shields the Earth against harmful particles in space. The field is unstable and has changed often in the history of the Earth. These field flips has scientist long suspected that happened more resent. The magnetic field creates magnetic poles that are near the geographical poles. A compass uses the geomagnetic field to find directions. Many migratory animals also use the field when they travel long distances each spring and fall. The magnetic poles will trade places during a magnetic reversal.

The North Magnetic Pole is the point on the surface of Earth's northern hemisphere where the planet's magnetic field points vertically downwards. There is only one place where this occurs, near to (but distinct from) the Geographic North Pole. The Earth’s magnetic field is attributing to dynamo effect, of circular electric current. However, it is not just constant in one direction. Scientist tests rocks to see that in a same place but different age show that they have different of permanent magnetization.

Its southern hemisphere counterpart is the South Magnetic Pole. Since the Earth's magnetic field is not exactly symmetrical, a line drawn from one to the other does not pass through the geometric centre of the Earth.

The Earth's North and South Magnetic Poles are also known as Magnetic Dip Poles, referring to the vertical "dip" of the magnetic field lines at those points.

References:

https://en.wikipedia.org/wiki/Earth%27s_magnetic_field - 19.10.2015

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magearth.html - 19.10.2015 http://www.uio.no/studier/emner/matnat/fys/FYS3610/h04/undervisningsmateriale/Chapter%202_2708.pdf