The ancients worshipped her. The Japanese still venerate her. As patriarchy developed, she became he; Helios and Apollo to the Greeks, and Ra, the supreme god, in Egypt.
Yet we are only now starting to understand the sun and its various moods; moods that have led a worried insurance consortium to contact Andrew Coates, at the Mullard Space Science Laboratory, part of University College London.
The sun is a rather insignificant star among its 100 billion siblings in our galaxy. But as our nearest star it is sovereign of our sky: the hub of our solar system and provider of heat and light. Earth would fit 109 times across the sun's disc; the sun's interior could hold more than 1.3 million earths. A gaseous ball, the sun's core is an immense nuclear furnace, fusing hydrogen into helium and generating the energy that is heat and light.
The solar wind is a result of the immense heat. Gases continuously boil off the sun's surface and their particles speed towards earth at more than 500km per second. Normally the earth's magnetic field helps buffer us from these particles, but when the wind turns into a gale they can penetrate our magnetic shield. For the billion-dollar satellite industry that circles out sky, the results can be catastrophic.
"Each lost satellite can be a $200m loss", says Dr Coates, "and the insurance industry is worried because it is losing money." This week he began investigating how the sun causes satellites to fail.
Just like a hormonal teenager, the sun goes through a phase every 11 years, known as the solar maximum, when it is spotty and bad-tempered. The greater the number of sunspots - dark patches where the solar magnetic field is exceptionally strong -the more violent is the sun's activity and magnetic eruptions, known as coronal mass ejections, become more common and intense. These huge bubbles of boiling gas threaded with magnetic field lines explode with the power of one billion hydrogen bombs, according to Nasa, and spray their particles into space.
"Normally the solar wind is a fairly constant flow of 1 million tons per second. When a coronal mass ejection occurs, 10 billion tons of particles erupt and some are addressed to earth," says Coates. At solar maximum, four such eruptions can happen per day.
"If the solar wind did not exist, the earth's magnetic field would be like that of a bar magnet in space," says Coates. "But like pushing on an invisible balloon, the solar wind compresses the field on the front [day] side and the night side moves away from the earth like a comet's tail."
Coronal mass ejections push the magnetic field in even further, from 60,000 km in front of the earth to around only 36,000 km. This is within the geostationary ring where satellites are positioned and can cause problems. However, the danger of solar maximum is not just one of compression.
"When the solar magnetic field is opposite to that of the earth, magnetic reconnection occurs and all hell breaks loose," says Coates. The result is an explosive process over a small volume that rips the earth's magnetic shield. Solar particles fly through the fissure. Once inside the Earth's magnetic field, they are accelerated.
Once all we knew of such geomagnetic storms were beautiful auroras, the dancing curtains of light seen at the poles. In a technological age, chaos can ensue: in the last solar maximum in 1989, the entire Quebec power system went down due to such a huge current of particles. However, as we become more dependent upon satellite communication, the danger will increase.
"To supply the mobile phone and internet demand, hundreds of satellites are being planned that will orbit the earth in the heart of the radiation belt," says Dr Coates. "Satellites have failed in the past and we need to know why."
His project is to build the communication satellite prototype of the aeroplane black box. Only this is a box that will never be retrieved. Instead, it will continuously send information about energetic particle conditions to earth. At the same time he will look at satellite losses from the past and use the information to help predict future losses.
The black box won't be built in time for the next solar maximum, only a few months away. However, the maximum effects will last for another two years and the black box will be ready during this time. So, as Coates puts it, all we can do for now is to hold our breath.
