Updated: Tue, Apr 3, 2001, 5:39 PM ET (2139 GMT)
Originally Posted: Tue, Apr 3, 2001, 11:06 AM ET (1506 GMT)
The most powerful solar flare ever recorded was detected late Monday, but astronomers said that it should not pose a major threat to the Earth. The flare, originally classified as an X17 but later upgraded to X20, was detected at 5:51 pm EDT (2151 GMT) Monday by ground- and space-based instruments and linked to a large, active sunspot region that has been generating flares and coronal mass ejections for several days. The previously record holder was another X20 flare in August 1989. The flare is considerably more powerful than a March 1989 flare, classified X15, that knocked out portions of the electrical grid in Quebec for several hours. However, this flare is not directed towards the Earth, so solar scientists are not anticipating effects as severe. The flare may create geomagnetic activity like storms last week that generated aurorae visible in the northern hemisphere as far south as southern California, Arizona, and Houston, and as far north in the southern hemisphere as Canberra, Australia. The shock from this flare is expected to arrive in the vicinity of Earth between 6 pm EDT (2200 GMT) Tuesday and 6 am EDT (1000 GMT) Wednesday.

Related Links:

•  SOHO information about X17 flare
•  SpaceWeather.com
•  NASA press relase