April 05, 2001
On Monday April 2, 2001, sunspot region 9393 (see yesterdays EPOD) unleashed a major solar flare. It appears to be the biggest flare on record, and definitely more powerful that the famous March 6, 1989 flare which was related to the disruption of the power grids in Canada. The big explosion, which took place near the Sun's northwest limb, hurled a coronal mass ejection (CME) into space at a speed of roughly 7.2 million km/h - but fortunately not directly towards Earth.
Solar ejections are often associated with flares and sometimes occur shortly after the flare explosion. CMEs are clouds of electrified, magnetic gas weighing billions of tons ejected from the Sun and hurled into space with speeds ranging from 12 to 1,250 miles per second. Depending on the orientation of the magnetic fields carried by the ejection cloud, Earth-directed CMEs cause magnetic storms by interacting with the Earth's magnetic field, distorting its shape and accelerating electrically charged particles (electrons and atomic nuclei) trapped within. Severe solar weather is often heralded by dramatic auroral displays, northern and southern lights, and magnetic storms that occasionally affect satellites, radio communications and power systems. This flare and solar ejection also generated a storm of high-velocity particles, and the number of particles with ten million electron-volts of energy in the space near Earth was now 10,000 times greater than normal following the flare.