Information

The Earth has a comparatively strong magnetic field that is formed in its interior. The outer boundary is called the magnetopause. The strength and direction (the magnetic poles are not identical to the geographical poles) of the magnetic field are subject to temporal variations, which can be observed through a marked annual migration of the magnetic poles. This is also responsible for the magnetic variations of a compass. The magnetic field is distorted at some distance from the Earth by the Interplanetary Magnetic Field. On the sunward side it is compressed and on the side facing away from the sun there is an elongated magnetic tail. Charged particles ejected from the Sun (solar wind) collide with the magnetic field. Some of the particles circulate near the Earth in the Van Allen radiation belt occasionally entering the Earth's atmosphere at the poles, which results in the polar lights, also known as auroras. The majority of the particles though is deflected far out into space along the magnetic field lines on the dark side of the planet.
A. Schulz, E. Astor; Ü: J. Moar, M. Dahl