The second massive sunspot to be spotted in less than a week could leave airline navigation and satellite communication systems vulnerable to disruptions for even longer than was previously predicted. Spectacular aurora at both poles are also forecast.
The US National Oceanic and Atmosphere Administration (NOAA) issued its first warning on 22 October. It said unusual solar activity associated with a giant sunspot could cause increased geomagnetic disturbances and radio frequency blackouts in the days that followed.
The sunspot was 10 times bigger than the Earth. That is roughly 10 times larger than normal, according to Larry Combs, a space weather forecaster at NOAA's Space Environment Center in Boulder, Colorado.
Giant sunspots are not uncommon, but they normally only occur at the peak of the 11-year solar season, which was in 2000. Combs says seeing them now is like getting a hurricane outside the hurricane season. The appearance of two together may be unprecedented.
Such turbulent solar activity can produce massive bursts of electromagnetic radiation across a broad range of frequencies. The most notable in terms of their effect on Earth are X-rays, which can cause havoc with radio frequency communications.
On top of this, large sunspots can also cause huge eruptions of the solar surface, known as coronal mass ejections (CME). When this happens billions of tonnes of plasma is kicked out into space and occasionally towards Earth, says Louise Harra, head of solar physics at the Mullard Space Science Laboratory in Surrey, UK. Two such events occurred on Sunday.
If the magnetic field of these eruptions opposes the Earth's magnetic field they can disrupt to satellites and communication systems, she says. The X-ray bursts take only minutes to reach Earth, while the electrons and protons that compose CMEs can take two or three days.
In the past, CMEs have caused problems with satellites and in 1989 one even took out an electricity grid system in Quebec, Canada. This time around, however there have only been unconfirmed reports of satellite phone systems being affected.
And some experts are sceptical that they pose a real threat to modern space equipment. "Spacecraft tend to be designed to be a little bit more robust than they were 10 or 15 years ago," says Mike McKay, director of the European Space Agency's Mars Express and Smart 1 missions, at the European Space Operations Centre in Darmstadt, Germany.
So far the solar disturbances have had no effect on ESA's spacecraft, with one exception. The X-ray Multi Mirror (XMM) space observatory has temporarily had its X-ray sensors turned off, says McKay, just to be on the safe side.
All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.
If you are having a technical problem posting a comment, please contact technical support.
20:00 03 July 2008
