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2 A very short tour of the major solar system plasmas

2.1 What is a plasma?

A plasma is a gas of charged particles. As they are charged, electromagnetic fields affect their motion, and therefore the dynamics of the plasma. Also, the charged particles can carry currents creating electromagnetic fields.

    • 2.2

      Solar system plasmas

      • 2.2.1

        The sun

High temperature matter is ionized the sun is a plasma

2.2.2 The solar wind

A wind of charged particles flows out from the sun through the solar system interplanetary space is filled with a plasma

2.2.3 Ionospheres Ionizing radiation + atmosphere = ionosphere

  • UV-, gamma, and X-radiation from the sun can ionize particles in a planetary atmosphere

  • Cosmic radiation can also cause ionization

  • When ionizing the gas, the radiation is stopped by the atmosphere and to not penetrate further

down. Therefore, only the upper layer of the atmosphere is ionized plasma. This plasma is called the ionosphere.

All planets with atmospheres has an ionosphere: Venus, Earth, Jupiter, Saturn, Uranus, Neptune. In addition, comets evaporates a gas cloud (because of radiation from the sun) which is partly ionized, causing a cometary ionosphere.

2.2.4 Magnetospheres

Solar wind + planetary magnetic field = magnetosphere Thus, all magnetized planets have magnetospheres: Mercury, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

  • As the particles in the solar wind are charged, their motion is affected by magnetic field from the planets.

  • Also, the charged particles in the solar wind can carry a current that can change the magnetic fields.

  • The net result is that the solar wind is deviated by the magnetic field of a planet, and that this

magnetic field is confined to a region called the magnetosphere.


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