The Earth's magnetosphere

The Earth

. The Earth’s magnetic field carves out a hollow in the solar wind, creating a protective cavity called the magnetosphere. The Earth, its auroras, atmosphere and ionosphere, and the two Van Allen radiation belts all lie within this magnetic cocoon. Similar magnetospheres are found around other magnetized planets. A bow shock forms at about ten Earth radii on the sunlit side of our planet. Its location is highly variable since it is pushed in and out by the gusty solar wind. The magnetopause marks the outer boundary of the magnetosphere, at the place where the solar wind takes control of the motions of charged particles. The solar wind is deflected around the Earth, pulling the terrestrial magnetic field into a long magnetotail on the night side. Electrons and protons in the solar wind are deflected at the bow shock (left), and flow along the magnetopause into the magnetic tail (right). Electrified particles can be injected back toward the Earth and Sun within the plasma sheet (center).

Copyright 2010, Professor Kenneth R. Lang, Tufts University