8. Magnetic field of Earth

A magnetic needle, when freely suspended at a point, comes to rest roughly along the geographical north-south direction on the Earth. The suspended magnet demonstrates that the Earth acts like a giant magnetic dipole, with its magnetic poles near the geographical poles.

 

The magnetic north (\(Nm\)) pole is located near the geographic south (\(SG\)) pole of the earth, and the magnetic south (\(Sm\)) pole is located near the geographic north (\(NG\)) pole of the earth.

 

Since unlike poles attract each other, the north pointer in the compass attracts the south magnetic (\(Sm\)) pole of the Earth. Similarly, the north pointer in the compass eventually points to the Earth's geographic north (\(NG\)) pole, as shown in the above figure. This is because the south magnetic (\(Sm\)) pole is located near the geographic north (\(NG\)) pole.

Likewise, the needle's magnetic south (\(Sm\)) pole is also attracted by the Earth's magnetic north (\(Nm\)) pole situated at the geographic south (\(SG\)).

The Earth's magnetic field strength has a magnitude of \(25\) to \(65\) \(micro\ tesla\), which is \(20\) times stronger than a fridge magnet.

A magnetic neutron star called Magnetar is situated in the Milky Way Galaxy. It is the most powerful magnet in the universe, with a diameter of \(20\ kilometres\). The mass of the Magnetar is two to three times that of the Sun.

 

A neutron star's magnetic field is so deadly that it can consume all the iron atoms in a living body's bloodstream (hemoglobin) even though it is \(1000\ kilometres\) away.

1. Pigeons have incredible navigational skills naturally. Even if the pigeons are kept somewhere they have never been before, they will be able to find their way back home. The magnetite present in their beaks allows them to detect the Earth's magnetic field.

2. Sea turtles return to their birth beach from the ocean to nest and lay eggs even several decades after their birth. It is found from the researches that the turtles can detect and remember changes in Earth's magnetic field. This recollection aids them in their journey back to their homeland.