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| By-NASA |
A large number of sunspots,hidden beneath the white flashes in this ultraviolet image (left) captured by the SOHO satellite in January, indicates that the sun is at or near the height of its 11-year cycle of activity. The sunspots, signs of powerful shifts in our star's magnetic field, intensify the heating of the sun's corona, increasing the amount of radiation emitted by the sun. At solar maximum the sun can blast a billion tons of matter into the solar system at speeds of more than a million miles an hour. Such bursts trigger geomagnetic storms that, if strong enough, may increase the size and geographic range of auroras and disrupt the operation of communications satellite and electrical power systems on earth.