The Earth was bombarded by charged particles from a series of huge solar eruptions at the end of October and beginning of November 2003. The first flare on 28 October and its associated plasma eruptions into space, was the largest experienced by Earth in 30 years, and knocked out two Japanese satellites, affecting telecommunications, air transport and power grids across the world.
A further flare on 4 November seems to have been even larger and saturated sensors designed to measure solar X-rays on the GOES satellite. The magnetic storms could have been much worse if they had been directed towards the Earth and their magnetic fields aligned differently.
The flares were emitted from the solar active region 10486, a group of large sunspots with an unusually com-plex magnetic field, rotating across the surface of the Sun.
Solar flares occur when twisted magnetic field lines com-ing out of the sunspots suddenly reconnect, releasing stored energy. Normal sunspots have one north pole and one south, but this one had two norths and a south.
The resulting visible light, X-rays and gamma rays, reached Earth in minutes. The flare then launched a stream of high energy protons traveling at up to 1500 km per sec-ond that eventually reached Earth and reacted with its mag-netic field to produce some spectacular auroras.
The auroral cloud was observed in many parts of the world. In Australia it was seen as far north as Wollongong and Perth.
According to NASA, despite the extreme effects, the flares were not as intense as those of 2 September 1859, which melted telegraph wires, largely because its magnetic field was not aligned exactly opposite to the Earth's. It isimpossible to tell whether this year's flares were freak events, or part of an ongoing trend, as satellite measure-ments of solar flares only began in 1976. However, polar ice cores suggest that the sun is more active today than it was 1000 years ago.
Magnetic storms can induce strong currents in power grids, build up charge on satellites and disrupt radio com-munications. For the October/November storms, satellites were shut down and voltages reduced on power grids. Airlines rerouted flights that crossed Polar regions where magnetic disruptions are strongest.
The flares came at a time when US funding to the US Space Environment Center (SEC) is in danger of being cut, thereby reducing any ability to forecast solar storms.