Magnetic field of the Earth

Earth's magnetic field is slightly tilted with respect to the planet's spin axis; there is currently a difference of about 11° between the two. Earth's magnetic field extends thousands of kilometers (miles) outward into space. The field forms a gigantic magnetic "bubble" in space around Earth. This magnetic bubble is called the magnetosphere.In addition to sources in Earth’s core, the magnetic field observable at the planet’s surface has sources in the crust and in the ionosphere and magnetosphere.Today the north magnetic pole is located about 700 miles(1,200 km) south-southeast of the north (spin) pole of the Earth (see red star on globe to left). Many times in the history of the Earth the core’s electrical currents have reversed direction, causing the north and south magnetic poles to switch positions!

The strength of the field at the Earth's surface ranges from less than 30 microteslas (0.3 gauss) in an area including most of South America and South Africa to over 60 microteslas (0.6 gauss) around the magnetic poles in northern Canada and south of Australia, and in part of Siberia.The field is similar to that of a bar magnet, but this similarity is superficial. The magnetic field of a bar magnet, or any other type of permanent magnet, is created by the coordinated spins of electrons and nuclei within iron atoms. The Earth's core, however, is hotter than 1043 K, the Curie point temperature at which the orientations of spins within iron become randomized. Such randomization causes the substance to lose its magnetic field. Therefore the Earth's magnetic field is caused not by magnetized iron deposits, but mostly by electric currents in the liquid outer core.