4 November

2003: On 4 November 2003, sunspot region 10486 released a massive solar flare, bigger than anything yet seen in recorded observational history.

The flare saturated the X-ray detectors on several monitoring satellites. It was estimated as an X25 intensity flare, a level never seen before by ESA's SOHO spacecraft.

The associated coronal mass ejection (CME) came out of the Sun's surface at about 2300 kilometres per second (8.2 million km/h).