[ Back to EurekAlert! ] Public release date: 7-Nov-2003
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Contact: Monica Talevi
monica.talevi@esa.int
31-071-565-3223
European Space Agency

The biggest solar X-ray flare ever is classified as X28

On Tuesday, 4 November 2003, this flare saturated the X-ray detectors on several monitoring satellites. The associated coronal mass ejection (CME) came out of the Sun's surface at about 2300 kilometres per second (8.2 million km/h). Only part of the CME is directed towards Earth, so we expect the Earth will receive only a glancing blow, since the source region is pointing away from us on the right on the limb of the Sun as seen from Earth.

How we classify solar flares

Scientists classify solar flares according to their brightness in the x-ray wavelengths. There are three categories: X-class flares are big; they are major events that can trigger radio blackouts around the whole world and long-lasting radiation storms in the upper atmosphere.

M-class flares are medium-sized; they generally cause brief radio blackouts that affect Earth's polar regions. Minor radiation storms sometimes follow an M-class flare.

Compared to X- and M-class events, C-class flares are small with few noticeable consequences here on Earth.

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