The Sun, even during its calmest periods, emits more energy per second than the entire human race could produce in several trillion years. As solar activity develops over its 11-year cycle, the Sun becomes increasingly violent, notably in areas of sunspots. Solar flares become more frequent, and the solar wind, the constant stream of charged particles emanating from the solar surface, increases in volume. Occasionally the Sun blows huge clouds of charged plasma – an ionised gas – into space, in a process known as a coronal mass ejection (CME). These events are collectively referred to as solar storms, or space weather storms.
It has only been in recent decades, with the advent of the Space Age and increasing reliance on technology, that humans have really felt the effects of the Sun’s activity. The majority of solar storms do not affect the planet, as the Earth is protected by a powerful magnetic field which deflects most of the radiation and charged particles that come its way. During a CME, however, ejected plasma, carrying with it the Sun’s magnetic field, may collide and interact with the Earth’s magnetic field, causing a geomagnetic storm in the magnetosphere above our atmosphere.
If enough charged particles then make it into Earth’s atmosphere, as well as causing the magnificent aurorae in the polar regions, they can severely disrupt communications satellites, radio transmissions and even power grids. Global positioning systems can be affected by geomagnetic storms, as can mobile phone and some TV networks which rely on satellites to broadcast information.
The effects of solar activity go beyond communications and power disruption. Oil and gas pipelines can become corroded because of currents induced by storms. Magnetic compasses can veer off course, and even homing pigeons can become confused! Astronauts are vulnerable to the effects of radioactivity from solar outbursts while they are outside Earth’s atmosphere, but so too are the passengers on some high-altitude jet planes.
A major event occurred just recently, in February this year: a series of flares, one a huge ‘X-class’ flare with associated CME, the largest in over four years. Despite the size of these events, there was little disruption on Earth because the relative orientation of the magnetic fields meant that the effect was dampened. Reports of beautiful aurorae came in on Valentine’s Day, however, from observers as far south as Northern Ireland in the UK.
Previous solar outbursts have not been so kind. In 1859 a particularly violent solar storm caused telegraph wires to short out in the US and Europe, resulting in widespread fires. A similar event today could be catastrophic. Modern power grids are highly interconnected, and a failure in one system could potentially cause a cascade of failures, with consequences similar to those of earth-based disasters like earthquakes: loss of water, heating, refrigeration, phone, transportation etc. Moreover, mobile phones might also be out of action because of damage to satellites.
Events within living memory include a ferocious solar storm in 1989, during which the Canadian city of Quebec lost all its power. The storm induced currents in its power grid, causing the transformers to melt. And in 2003, during two weeks of violent solar activity, several satellites were knocked out of action. Scientists predict further large-scale storms sometime in 2012-2013, the next high point in the Sun’s 11-year cycle. The recent flare may have just been for starters.
Space weather expert Professor Daniel Baker assures the public, however, that with an increased understanding of space weather and the progress made by scientists and engineers, humans should be able to build systems that will counteract the worst effects of solar violence. As he says, “it will be interesting to see how well our technological systems will withstand the rigors of space weather as the sun gets back to higher activity levels”. It’s worth hoping that they hold out.