solar wind

Stream of atomic particles, mostly protons and electrons, from the Sun's corona, flowing outwards at speeds of between 300 kps/200 mps and 1,000 kps/600 mps.

The fastest streams come from ‘holes’ in the Sun's corona that lie over areas where no surface activity occurs. The solar wind pushes the gas of comets' tails away from the Sun, and ‘gusts’ in the solar wind cause geomagnetic disturbances and auroras on Earth. Other planets are also affected: the European Space Agency's probe Mars Express (to be launched in 2003) will investigate how the solar wind affects that planet's atmosphere.