Could a solar flare wipe out life on Earth?
I was watching a movie where a super solar flare was about to enter the Earth and destroy all living things on the planet. Could this happen?
I was watching a movie on TV where a super solar flare was about to enter the Earth and destroy all living things on the planet. Could this happen?
"The short answer is no," says Dr David Neudegg, from the Australian Ionospheric Prediction Service, which monitors space weather.
"Solar flares do occur regularly but their impact on the Earth is considerably less dramatic than this movie. There is no evidence to suggest that they have ever had a destructive impact on life on Earth."
Solar flares are basically a release of energy from the Sun, and they usually happen around sunspots — which are small areas where the Sun's magnetic field is poking out of its surface in loops.
"The magnetic field loop breaks and releases light in the x-ray spectrum. This light takes eight minutes to get to the Earth where it is absorbed in the upper atmosphere or 'ionosphere' about 100 kilometres above us," says Neudegg.
"While there is a fair amount of energy being dumped on the Earth, we won't really notice it here at ground level. The only impact it may have is on shortwave radio users, who may experience some fadeouts."
What can cause more disruption to technology are coronal mass ejections (CMEs), which often accompany the larger solar flares.
"CMEs carry mass, in the form of protons and helium atoms, as well as a shock wave, while solar flares don't," says Neudegg, "they take on average 40 hours to reach here and most of them miss us as the Sun fires them out in all directions and Earth is a small target."
Those that don't miss us hit the Earth's magnetic field, which protects the upper atmosphere about 70,000 kilometres away from us.
"Quite a lot of CMEs don't do anything, but a big one can push the magnetic field in towards the Earth for a few minutes or hours."
The effect of a CME depends on the Sun's magnetic field orientation, which changes overall polarity every 22 years or so (reflected in the 11 year sunspot cycle) but varies its north-south direction near Earth every few hours.
If the Sun's magnetic field orientation aligns with the Earth's magnetic field at the time of the CME shock wave, you can get a geomagnetic storm that causes large electric currents in the upper atmosphere. These currents may cause impacts on the high voltage transformers on powerlines designed to transport electricity over long distances.
"There have been maybe three CMEs that have caused heavy damage to power grids — Quebec, Canada in 1989 being the most serious, with several days outage," says Neudegg.
Even though polar regions are more at risk, it's possible that something similar could occur in Australia, but it also depends on the underlying geology and complexity of the power grid.
Power regulatory agencies and companies are working with the IPS to predict large CME events, and to develop strategies for dealing with any disruptions.
GPS could be affected
Some forms of modern technology that rely on satellites — such as GPS or long distance communications via satellite or short wave radio — could be affected by a large CME.
"Spacecraft will suffer as they'll get a lot of particle radiation, and that can damage them," says Neudegg. "If a lot were knocked out then we might have an issue with GPS and communications that use satellites."
On the whole though, there's not much to worry about with the Sun as far as events catastrophic to life, at least not for a few more billion years.
"The Sun is a very stable, boring average star in the middle of its lifespan, which is one reason that life has survived here for so long. The event that will really damage the Earth is the death of the Sun, but that won't be for about five billion years."
Dr David Neudegg was interviewed by Kylie Andrews.
Published 23 November 2011