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Skywatching

The 'solar maximum' is coming

Secrets of sun spots

It has been predicted that next year will probably mark the maximum of the Sun's magnetic current activity cycle. The last one was around 2013. So, what should we expect this time round?

In the 17th Century, Galileo discovered the Sun has spots. They are areas, far larger than our Earth, where the magnetic fields are so strong they inhibit the flow of energy coming up from inside the Sun. That makes them cooler than their surroundings, so by comparison they look dark.

They are still very hot, around 3,000 C, compared with their 6,000 C surroundings. Observers found the sunspots came and went in a 10 to13-year rhythm. At times, the Sun appears completely clear of spots and then, several years later, it can be covered with hundreds of them.

The magnetic fields that generate sunspots originate deep down inside the Sun, where solar rotation, convection and other movements of very hot, highly conductive plasma act like a dynamo, generating intense electric currents and great ropes of magnetic fields.

The numbers and size of the sunspots give us a sort of stethoscope on what the "magnetic machine" inside the Sun is up to.

There are other manifestations of this magnetic activity. On occasion great loops of magnetic field emerge from the surface, get twisted, stressed and explode, releasing the energy of millions of hydrogen bombs in seconds or minutes, producing bursts of X-rays and jets of high-energy particles that can destroy our satellites and impose radiation threats on space travellers.

On occasion, a great loop, containing magnetic fields and hot plasma, snaps and catapults into space at up to thousands of kilometres a second. We call these “coronal mass ejections,” although they are often referred to as “solar storms.” If they hit the Earth's magnetic field, we get magnetic storms, power outages and problems with communications. They also give us spectacular displays of the aurora.

For much of our history, the only impact solar magnetic activity had on our ancestors was an occasional display of the aurora. However, things started to change as our lives became more and more dependent on technology. Problems began when we started connecting ourselves together with long lengths of metal—the telegraph, telephone, power networks, pipelines and railways.

Magnetic storms driven by the Sun induce electric currents in those networks, causing failures, degradation and enhanced corrosion. Radio communications are also affected by the Sun. Basically the Sun affects our connectivity.

Over the last decade, since the last solar activity maximum, we have increased our connectivity and have become more dependent on it for many aspects of our work and daily lives. The Internet is now at the core of what we do. Cloud computing and data storage involves our putting our data and programs on huge computer server farms that can be far away. The potential vulnerability is in our connection with them. Using optical fibre for communications is a help, because magnetic storms can't induce currents in glass, which makes them largely invulnerable to solar interference.

However, there is a new dimension. In order to provide Internet access anywhere on Earth networks of thousands, or tens of thousands, of satellites are being launched. How the Sun will affect those networks remains to be seen, although the high degree of redundancy will help.

As a species, our curiosity and inventiveness will continue to bring us new capabilities and new challenges, from the Sun and elsewhere.

•••

• Saturn lies in the southeast after sunset, with Jupiter in the east.

• Venus rises shortly before dawn.

• The Moon will be new on Dec.12.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.



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About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected]



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The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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