Why is the Earth Magnetized?
One theory is that the core consists largely of molten iron and that convection caused by the heat from the core causes liquid iron to move in a rotational pattern. Sir Joseph Larmor proposed that the Earth was a dynamo in 1919. In the middle of the 20th century geologists made a remarkable finding – some ancient rocks showed the earth’s magnetic field had pointed in the opposite direction. It seems likely the polarity of the earth has shifted around several times. There are predictions that the magnetic polarity of the earth may reverse again in 1,500 to 2,000 years. This is going to upset a lot of birds, fish and bumblebees, if they are still around. Findings that the magnetic fields of some other planets are not aligned similarly with rotation also bring into question the dynamo theory.
