The upper atmosphere suddenly lit up like a Christmas tree under infra-red radiation at the beginning of March. A violent solar storm was to blame, spewing out a huge cloud of charged solar particles that swept past the earth at high speed.
This solar storm heated up the upper atmosphere with a huge blast of energy of 26 billion kilowatt hours, according to NASA. This was sufficient energy to power the homes of a city like New York for two years.
“This was the biggest dose of heat we've received from a solar storm since 2005,” according to solar researcher Martin Mlynczak of Nasa's Langley Research Centre. “It was a big event and shows how solar activity can directly affect our planet.” Luckily in this case the effects were primarily spectacular polar lights, but these geomagnetic storms generated by the interaction between the electrically-charged solar particles and the earth's own magnetic field could have more serious consequences.
They are able to overload electricity supply networks and cause breakdowns, cause communications and navigation satellites to fail, and endanger astronauts and people in aircraft.
Geomagnetic storms are a serious hazard to a highly technological society in the view of British space weather researcher Mike Hapgood, writing in the journal Nature .
In the view of the professor at the Rutherford Appleton Laboratory, we are ill prepared for this threat and need to be able to assess better the probability of severe space weather disruptions and their effects. There have always been solar storms, but our increasingly technology-dependent civilisation is becoming more susceptible. There is evidence of damage caused by solar eruptions since the time electricity first began to be harnessed. An exceptionally powerful solar storm knocked out the newly introduced telegraph cables in early September 1859, causing fires in telegraph stations and also generating polar lights that were visible as far south as Rome and Havana.
The effects today could be much worse.
A study by the British electricity and gas supplier, UK National Grid, indicated that an event of this kind could cut electrical supplies to certain regions for months.
A solar storm in mid-March 1989 did in fact disrupt power supplies to millions of Canadians for several hours and cut contact with around 1,600 satellites.
Since then many electricity networks have improved their equipment, but preparations need to be made, not only for events similar to those in the past, but also for the extreme events that might arise only once in a thousand years.
The first need is to assess the risks better. This would be possible with the aid of numerous historical records, although these are largely not yet available in electronic form.
In addition solar weather forecasting needs to improve, Hapgood says. Nasa's “STEREO” solar satellites indicate that reliable warning of at least six hours to an accuracy of one hour is possible.
US aviation authorities are currently calling for international standards for space weather briefings for aviation.
Passenger flights may need to avoid severe solar storms under certain conditions, particularly on polar routes.
Solar storms occur when the sun hurls large clouds of electrically charged particles into space and these strike the earth. The solar cycle takes around 11 years to complete.
“We are currently emerging from a deep solar minimum,” says James Russell, a colleague of Mlynczak's at Hampton University.
He predicts the cycle will rise in strength to a peak in 2013. In addition the sun is in a big maximum phase that has occurred 24 times over the past 9,300 years and is currently approaching its end.
This “solar climate change” does not necessarily mean a calmer period in space weather, as Luke Barnard of Reading University in Britain has deduced.
According to his analysis, the chance of isolated extreme space weather events in the next 40 years has risen by around a half, as Barnard reported at a recent gathering of British astronomers.
There is a precedent for this. The big solar storm of 1859 took place outside a large solar maximum.
