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Sunday, 20 February, 2000, 18:07 GMT
'And here's today's space weather forecast...'
By BBC News Online's Damian Carrington in Washington DC
Space weather has joined earthquakes, hurricanes and gales in having official scales of severity. The worst events on the scale are accompanied by some severe impacts on human activities.
The scales have been announced just as the Sun's 11-year cycle of activity is reaching its maximum.
"When you go from a freezing spell to a heat wave, that's just 100 degrees Fahrenheit (38 Celsius) of change - when a space storm strikes, the flux of energetic particles jumps by 10,000 times." Power grid collapse His comments were made at the annual meeting of the American Association for the Advancement of Science (AAAS).
Geomagnetic storms result from the Sun's magnetic field pushing into the Earth's. The most severe of these, a G5 event, could cause power grids to collapse and transformers to be damaged. Satellite navigation systems would fail for days and aurorae could be seen at the tropics. Commercial aeroplanes Even G3 events, 50 times more common, would trigger false alarms and interrupt radio navigation signals.
Finally, a radio blackout scale has been produced. Here the extreme events would cause "complete high frequency radio blackout on the entire sunlit side of the Earth lasting for hours". Even Moderate R2 events, of which 30 are expected every year, can lead to blackouts for mariners and aviators for tens of minutes.
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18 Feb 00 | Washington 2000
18 Feb 00 | Science/Nature
07 Feb 00 | Science/Nature
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