Solar activity



Perhaps the most newsworthy item of recent times concerning solar activity is its unprecedented strength during the rising phase of its current 11-year cycle. Examples of its potency include a major, well-observed solar flare in March 1989 that launched an unusually powerful blast wave that, hitting Earth, caused spectacular low-latitude auroras and induced currents that disabled the Quebec power system for 9 hours (6 million customers). From August through October 1989, solar flares emitted the most intense levels of solar cosmic rays measured since the beginning of the Space Age; one flare produced more cosmic rays than the previous solar cycle in total. Radiation damage to the Magellan spacecraft, en route to Venus on a radar mapping mission, permanently reduced its solar-cell output by 10%. Excessive heating caused the Earth's upper atmosphere to rise, prematurely downing the one spacecraft capable of monitoring solar activity from orbit, the Solar Maximum Mission. Implications for the manned and unmanned space program of record-breaking solar activity are still being assessed.