Quick Look at Solar Wind Properties

ParameterMean Value5-95% Range
Speed (km/s)468320 - 710
density (protons/cc)8.73.2 - 20
Alfvenic Mach No.10.74.4 - 20
Sonic Mach No.7.75.6 - 10
|B| (nano-Tesla)6.62.2 - 9.9
Proton Temperature (K)120,00010,000 - 300,000
Electron Temperature (K)140,00090,000 - 200,000
Alfven Speed (km/s)5030 - 100
Sound Speed (km/s)6341 - 91

Other interesting facts about the solar wind:

  • Consists dominantly of protons and electrons in equal numbers with a small (~5%) amount of ionized Helium and an even smaller percentage of heavier ions.
  • The average solar wind takes about 4 days to travel between the corona and the Earth.
  • Most of the energy transported by the solar wind is in the form of kinetic energy. The solar wind carries 1.7E27 ergs/s of kinetic energy on the average through a sphere at 1 au. (Compare this to 0.05E27 ergs/s of thermal energy and 0.025E27 ergs/s of magnetic energy.)

Send feedback to Linda Johnson, lejohnso@engin.umich.edu.
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