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How we dodged a solar doomsday

The Sun put on an impressive display recently with the transit of the biggest sunspot in nearly 20 years. It had the potential to cause massive disruption but, as Megan Toomey reports, the event was benign and gave scientists plenty of material to study.

The Earth dodged massive disruption of its communications systems recently when AR12192, the largest sunspot seen in well over two decades, did not wreak the technological havoc that similar events have in the past.

Sunspots are active regions on the Sun made up of intensely complex tangles of magnetic fields – so intense, in fact, that light and heat cannot cross them, which makes them appear dark (although many of the images here, inlcuding the video above, show ultraviolet imaging that makes the sunspots appear bright).

During its rotation across the side of the Sun that faces Earth in late October, the sunspot fired off 10 big solar flares – large energy releases including X-rays and UV radiation. These solar flares are usually accompanied by coronal mass ejections, or CMEs – eruptions of plasma so big they burst into space.

Yet there was not a single significant CME from AR12192.

Solar flares aren’t always accompanied by CMEs, or vice versa. But the big ones usually are. And with so many sizable solar flares coming out of AR12192 – a sunspot almost as big as the planet Jupiter – scientists were left somewhat surprised.

AR12192, a sunspot almost as big as the planet Jupiter, erupted with a solar flare on 27 October 2014 during its first rotation. This image shows Earth to scale with the flare. – NASA/GSFC/SDO

So when the sunspot returned for a second rotation on 13 November, we expected to see plenty of action. As sunspots get older they become more likely to produce CMEs that could potentially cause some kind of shake-up to our technological systems. Scientists also thought that AR12192 would be even bigger than it was just two weeks before thanks to an imaging technique created to “see” the far side of the Sun by two scientists from North West Research Associates.

Still, nothing happened – nothing major, that is.

On 17 November NASA’s Solar Dynamics Observatory reported that the sunspot’s reappearing act had considerably less pizzazz this time around, AR12192 was only about a third of its previous size.

NASA’s team at the Goddard Space Flight Center knows that there is still a lot to learn about sunspots and the forces at work in them. So the ability to study so many flares from the sunspot – and how that sunspot evolves – will help them understand how solar flares are created, and when they will impact Earth.

Coronal loops are also found around sunspots and in active regions. They are associated with the closed magnetic field lines that connect magnetic regions on the Sun’s surface. Many last for days or weeks, but most change quite rapidly. – Solar Dynamics Observatory/NASA

Solar storms can bring down a range of electronics, from satellite communications to GPS navigation and power grids, causing mass power blackouts. It has happened many times in the past. One of the most recent events occurred in Quebec, Canada. On 13 March 1989, a geomagnetic storm caused the collapse of the Hydro-Québec power grid leading to a nine-hour blackout that affected six million people and resulted in damages and revenue losses of hundreds of millions of dollars.

These images of the Sun (7 December 2011) were taken at almost the same time, in various wavelengths in various temperatures and layers of the Sun. Active regions appear lighter. In addition, an illustration of the Sun's magnetic field lines was superimposed (on the right). – Solar Dynamics Observatory/NASA

But even that storm was trivial in comparison to the one in 1859, the most massive geomagnetic storm in recorded history. Within hours of this storm, known as the Carrington event, people in the United States and Europe saw the wires of their new telegraph services spontaneously spark, causing fires across the continents. At the same time, the phenomenon lit up the skies with aurorae – which usually appear huddled around the poles – as far south as Rome, Havana and Hawaii, and as far north as Queensland, Australia.

A pair of dynamic active regions that rotated into view as NASA’s Solar Dynamics Observatory caught the activity just over two days (15-17 August 2011). At left, plasma near the surface is shown at 60,000 degrees in extreme ultraviolet light. The middle portion with many looping arcs, also in extreme UV light, shows plasma heated to about a million degrees. The right portion shows the magnetically intense sunspots themselves that are the sources of all the activity. – Solar Dynamics Observatory/NASA

Scientists believe that a solar storm of this magnitude could happen again, at an intensity far worse than the storm in 1859. The effects of a geomagnetic storm can last days, or even weeks – and this could potentially spell doom for modern society, which relies so heavily on technology.

This filtered light image (Oct. 18-22, 2014) shows this substantial active region is 125,000 km wide, almost as big as the planet Jupiter, and many times the size of Earth. The region appears to have the kind of unstable magnetic field that suggests it might well produce more solar storms. – Solar Dynamics Observatory/NASA

Fortunately NASA has been working to give us an edge on predicting solar storms. Several spacecraft are already hard at work collecting data on solar flares and sunspots, and NASA is getting ready to launch four Magnetospheric Multiscale (MMS) observatories that will help us better understand Earth’s magnetic fields, which protect us from the worst of the CMEs.

Megan Toomey is a freelance journalist based in Melbourne.
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