March 9, 2012 7:42 pm
It’s been a damp solar squib – but watch the Sun, it’s rising
The Sun flared up this week – and so did the terrestrial media, with warnings of satellites frying in orbit and electric grids crashing as supercharged solar particles zapped Earth’s atmosphere. Then nothing much happened. A few airlines moved intercontinental flight paths away from the poles, but no significant damage had been reported by Friday night.
Yes, it has been a damp solar squib so far. But people should not write off the episode as another scientific scare story, in a long line including the Y2K millennium bug and various deadly viruses that mercifully failed to live up to their fearsome reputation.
Because the Sun is back, ramping up activity toward a predicted peak next year. There will be solar storms more severe than this week’s, throwing out more energetic particles that interact more strongly with Earth’s atmosphere and magnetic field. Then the intense radiation and electromagnetic oscillations could harm some of the 900 or so satellites in Earth’s orbit, while interrupting radio communications, sending navigation systems awry and possibly blacking out terrestrial power supplies.
Just a short while ago, between 2008 and 2010, solar scientists were preoccupied with the Sun’s unexpected silence. According to the longstanding 11-year solar cycle, activity should already have been building up from a minimum, after the previous peak in 2001, but there were hardly any sunspots or flares – leading some to speculate the cycle might be suspended for decades.
The last time the Sun shut down like that was during the cold period from 1645 to 1715, known as the Maunder Minimum. Although the Sun gives off almost as much light and heat when quiet as when stormy, climatologists believe that solar silence tends to have a cooling effect on Earth – which might have been useful as a slight antidote to man-made global warming.
Early last year the Sun woke up and since then its activity has been increasing in a way that mirrors past upswings, though this cycle is a year or two behind the usual schedule.
Predicting what scientists call “space weather”, the impact of solar activity on Earth, lags behind weather forecasting – as this week’s anticlimax showed. The key event is a “coronal mass ejection”, a gigantic bubble of super-hot particles bursting out from the Sun at several million miles per hour. This takes 20 to 30 hours to reach Earth, giving perhaps a day or so warning before a solar storm causes trouble here. The main forecasting problem is that the effects are very sensitive to small differences in the way solar particles interact with Earth’s magnetic field, which are hard to anticipate.
Governments are making a big effort to improve forecasting, because companies such as satellite operators and electric utilities can take some precautions to protect particularly vulnerable electronics if they are given reliable warnings.
What is the worst the Sun could throw at us? Last year US and UK government scientists memorably warned of a “global Katrina” costing $2tn, if the greatest solar storm on record – which ruined the world’s newly installed telegraph networks in 1859 – were to repeat itself now. Continent-wide electrical blackouts could last for weeks.
The most serious event in modern times was the collapse of the Hydro-Quebec grid during a solar storm in 1989, which left 6m people without power for nine hours. But voltage fluctuations in power systems, caused by oscillations in the geomagnetic field, have caused many smaller blackouts.
Even an intense solar storm has no health effect on people on the ground. Above Earth’s protective atmosphere, the burst of radiation may be dangerous and the International Space Station has a protected area where astronauts can shelter, though Nasa decided that this week’s storm was not severe enough for them to use it.
The world may be more vulnerable to an electromagnetic storm than it was during the last solar maximum 12 years ago, because it depends more on electronics for everything from navigation to computing.
Alan Woodward, professor of computing at the University of Surrey, believes a severe solar storm could be catastrophic if it shut down computer networks. “Without computers life as we know it would grind to a halt,” he says. “It is therefore scary to know that these computers are remarkably susceptible to electronic interference which can bring about this situation.”
Other experts are trying to calm such fears. Professor Eelco Doornbos, an expert on space weather at Delft University of Technology, believes the bigger solar storms still to come pose no significant risk even to the most exposed electronics in satellites. “Perhaps people react more emotionally to [space weather] because it’s extraterrestrial and therefore has something mystical about it,” he says.
The most mystical manifestation of space weather is the aurora borealis, or Northern lights, the glowing curtains that appear in the night sky when charged particles from the sun hit the upper atmosphere. An intense solar storm can bring the display down from its usual polar haunts to lower latitudes. Whatever the danger of electromagnetic havoc, the upside of having an active Sun again is that more people will experience the joy of Northern lights dancing in front of the stars.
The writer is the FT’s science editor
Copyright The Financial Times Limited 2012.
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