Canada vulnerable to Sun's bad behaviour, especially solar storms

A tale of a solar storm

Photo: Pixabay

The Sun

The interior of the sun is threaded with huge ropes and tubes of magnetic fields, loaded with very hot plasma—gas so hot its atoms are losing their electrons.

As the sun rotates and material flows up and down inside it, loops can develop in those magnetic ropes, causing them to rise to the surface (the photosphere), where they erupt as huge loops.

This is the story of one of them.

The solar surface is dotted with patches of enhanced magnetic fields, called active regions. These contain sunspots and constantly changing patterns of magnetic activity. It is in those that most of the dramatic phenomena take place.

A new loop has emerged, erupting through the surface and rising high into the million-degree but rarefied corona, where it becomes visible to our satellites and ground-based instruments.

It is large enough to contain hundreds of planets like ours, and still growing. Its feet are firmly anchored in the photosphere, where the constant motion and the emergence, rearrangement and decay of magnetic fields push its feet to and fro.

In addition, as it grows it comes into contact with other loops and magnetic structures. The result is increasing stress in the magnetic fields holding the loop together. These stresses may be localized, at the contact points with other loops, or distributed along the loop as it becomes overly stretched, or both. These give rise to huge electrical currents, which are carried by the free electrons in the plasma.

However, there are limits. Eventually the currents become too large to be carried by the available electrons and instabilities develop. These can release the stresses in gradual ways or in huge explosions, called solar flares. As the loop gets more and more stressed, it may reach a point where the currents become too huge to handle, and the loop snaps off and catapults out into space. If a flare or some other disturbance happens in the loop or nearby, they may cause it to lift off sooner.

Regardless, the result is always the same. A huge mass of plasma impregnated with magnetic fields gets shot off into space as fast as thousands of kilometres a second. The mass of fast-moving plasma is known as a "coronal mass ejection", or less accurately, "a solar storm."

While it is close to the sun we can see it and estimate whether it is coming in our direction. Then as it moves away, it becomes invisible. Depending on its speed and precise launch direction, the coronal mass ejection (CME) will take 36 to 48 hours to reach us.

There are two things about a CME that we really need to know. Firstly, exactly when it is going to arrive, and secondly the direction of its magnetic field. This is critical, because this can determine whether its collision with the our planet's magnetosphere is fairly benign or if it is likely to cause severe magnetic storms, which in turn can cause widespread power outages, communications blackouts and other damage.

At the moment, we don't know the precise arrival time or magnetic orientation of the CME until it passes the solar monitoring satellites that are sitting 1.5 million kilometres sunward from us. That gives us about 15 minutes' notice.

That is not enough time to prepare all of our vulnerable systems for possible disruption. Therefore, in Canada and around the world, a lot of effort is going into finding ways to learn the threat potential and precise arrival time as early as possible. Due to its high magnetic latitude, large geographic extent and low population density over much of the country, Canada is especially vulnerable to the sun's bad behaviour, so we have a special interest in better monitoring and understanding it.

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Saturn lies low in the south-east and Venus low in the east before dawn. Mars is low in the west after sunset and getting hard to spot. The Moon will reach its first quarter July 2.

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