Earth’s Magnetism

Earth’s Magnetism

Earth has been assumed or imagined by the scientists as a huge magnetic dipole. However, the position of the Earth’s magnetic poles is not South Geographic Pole North Magnetic Pole well defined in the Earth. The south pole of the imaginary magnet inside the Earth is located near the geographic north pole and the north pole of the earth’s magnet is located near the geographic south pole. The line joining these magnetic poles is called the magnetic axis.

The magnetic axis intersects the geographic north pole at a point called the north geomagnetic pole or northern magnetic pole. It intersects the geographic south pole at a point called the south geomagnetic pole or southern magnetic pole.

The most powerful magnet in the universe is actually a neutron star called magnetar (magnetic neutron star) located in the Milky Way Galaxy. The diameter of the magnetar is 20 kilometer and its mass is 2 to 3 times that of the Sun. Its magnetic field is so enormous and lethal that it is capable of absorbing all the iron atoms from the bloodstream (hemoglobin) of a living body even if it is positioned at a distance of 1000 km from it.

The magnetic axis and the geographical axis (axis of rotation) do not coincide with each other. The magnetic axis of the Earth is inclined at an angle of about 10° to 15° with the geographical axis.

The exact cause of the Earth’s magnetism is not known even today. However, some important factors, which may be the cause of the Earth’s magnetism, are as follows.

* Masses of magnetic substances in the Earth

* Radiations from the Sun

* Action of the Moon

However, it is believed that the Earth’s magnetic field is due to the molten charged metallic fluid inside the Earth’s surface with a core of radius of about 3500 km compared to the Earth’s radius of 6400 km.

Pigeons have extraordinary navigational abilities. It enables them to find their way back home even if you take them to a place where they have never been before. The presence of magnetite in their beaks enables them to sense the magnetic field of the Earth. Such a magnetic sense is called magneto-reception.

Earth’s Magnetic Field

A freely suspended magnetic needle at a point on the Earth comes to rest approximately along the geographical north south direction. This shows that the Earth behaves like a huge magnetic dipole with its magnetic poles located near its geographical poles. The north pole of a magnetic needle approximately points towards the geographic north (NG). Thus, it is appropriate to say that the magnetic north pole of the needle is attracted by the magnetic south pole of the Earth (Sm), which is located at the geographic north (NG). Also, the magnetic south pole of the needle is attracted by the magnetic north pole of the Earth (Nm), which is located at the geographic south (SG). The magnitude of the magnetic field strength at the Earth’s surface ranges from 25 to 65 micro tesla.

Earth’s magnet is 20 times more powerful than a fridge magnet.