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Earth, a giant magnet

Our planet creates its own magnetic field in the same way a dynamo does. The difference in the rotation rate between Earth and the fluid (molten metals) in its core generates this magnetic field. Earth’s magnetic field extends thousands of kilometers outward into space forming a gigantic “magnetic bubble” known as the magnetosphere.

The magnetosphere shields Earth from most particle radiation originating from the Sun as well as most cosmic radiation. The Sun is not only a source of light, it also sends out a continuous stream of electrically charged particles into space. These particles constitute the solar wind. They reach out into the farthest corners of our Solar System.

Magnetosphere protects earth

The Earth is protected against this corpuscular radiation by its intrinsic magnetic field. The solar wind – magnetosphere interaction leads to various phenomena:

  • auroral displays
  • deviations of the compass
  • radiation risks for air traffic and for space travel

All of this is accompanied by effects in different regions of the magnetosphere, but also with an impact on the upper atmosphere.

The magnetosphere is the region of space pervaded by the terrestrial magnetic field. It is a very complicated and dynamic region filled with plasma, with a rich variety of phenomena that occur as a result of the interplay between the Earth's field and upper atmosphere and the variable solar wind.

Magnetosphere, shape of a teardrop with a long tail

Shaped more like a teardrop, the magnetosphere is not actually a sphere, but has a long “tail” extending away from the Sun. The magnetosphere extends about 70,000 kilometers in the direction of the Sun and on the opposite side the magnetosphere’s tail stretches out many millions of kilometers.

The magnetosphere, however, is a dynamically active region. Under the influence of the solar wind, which is neither homogeneous nor stationary, the shape of the magnetosphere constantly varies. In extreme cases this environment can interfere with human activities, for example causing unwanted effects on spacecraft situated in this region of near-Earth space (Space Weather).

Interplanetary space, up to hundreds of thousands of kilometers from the Earth, where there is no more atmosphere, but where the magnetic field of our planet is still present. Copyright: SOHO/LASCO/EIT (ESA & NASA). Credit: Steele Hill, NASA.