The field strength varies in an 11-year cycle. The next peak will occur in 2000. The eruption of gas and plasma from the Sun's surface creates a wind of electrons, helium and hydrogen atoms and ions, and other charged and uncharged particles. There are high and low speed types of solar wind. The high speed wind originates from predominantly open magnetic field areas in coronal holes, and the low speed wind from the predominantly closed field lines near the equator.
Shock fronts emitted from coronal mass ejections can accelerate particles to high energies.
Image of the Sun in ultraviolet, showing a large prominence at the limb. Courtesy Space Physics Group, Oulu, Finland. The Earth's magnetosphere is where the Earth's magnetic field disturbs the Solar wind. Once perceived as an invisible shield protecting the Earth, scientists now see the magnetosphere as a leaky windsock filled with solar wind and the Earth's atmosphere. At the magnetic poles, the magnetic field lines are vertical, forming cusps or holes.