STARGAZING: A magnetic star

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton.

In early September, 1859, telegraph operators all over Europe and North America started to encounter serious problems.

The trouble started with an increasing number of transmission irregularities and failures. Some operators started getting electric shocks from their equipment. The Trans-Atlantic telegraph cable was really badly affected. In some cases the equipment caught fire.

It seemed as though an unknown source of electricity had been connected to the network. In some cases it was possible to disconnect the power supplies from the lines and run on this mysterious, free electricity that was being fed into the system. It was not immediately realized at the time, but the cause of the problems was the Sun. During the preceding month, observers had seen large numbers of spots on the Sun, indicating that our star was experiencing intense magnetic activity. There were also lots of displays of aurora, however, at the time the connection between the Sun and auroral displays was not fully accepted.

When we look at the Sun – WITH APPROPRIATE EYE PROTECTION – we see a yellow sphere in the sky. That is the way it has looked to us for as long as we have been around on the Earth, so we have not really considered that as being odd.

Books tell us that the Sun is a huge ball of very hot gas with a nuclear fusion reactor in the middle. However, if that were all the Sun is, it and all the other stars would be big fuzzy blobs. They’re not, so there has to be an additional ingredient or two. There are – magnetic fields. Just as when we heat a pan of water or cooking oil – the process is easier to see with the oil — hot material from deep in the Sun rises upwards towards the surface, where it cools and flows back down, setting up a continuous circulation known as convection. Making things more complicated, the Sun is rotating. All these flows of extremely hot gas generate electrical currents, which in turn generate magnetic fields. These magnetic fields change everything. They turn the hot gas into an elastic, stretchy material, able to form loops, streamers and giving the Sun a definite surface.

One property of elastic we are all familiar with is that we can store energy in it.  We have all stretched elastic bands and had them snap, releasing all that stored energy very quickly. All that churning motion in the Sun twists, stretches or compresses magnetic fields, storing energy. Most of the time the energy can be slowly released as the structures relax. However,  in some cases the stresses become too big, instabilities develop, the magnetic fields snap and all that stored energy, equivalent to millions or billions of hydrogen bombs, is released in a few seconds. This can result in a mass of solar material being catapaulted off into space at thousands of kilometres a second. These things, known as coronal mass ejections, reach the Earth in between one or two days and collide with the Earth’s magnetic field, triggering a magnetic storm. This is what caused all that trouble in 1859, and again, less intensely in March, 1989, causing a massive power outage in Quebec and problems around the world.

We live more complex lives today than we did in 1859, with a greater dependence upon communication, especially via the Internet. If that 1859 event were to be repeated today, the impact could cost us up to 2.6 trillion dollars. Because transformers and other power distribution hardware is extremely expensive, only small stocks of spares are kept, which could result it taking several months to repair the damage.

After sunset Jupiter is high in the southwest, and Mars and Saturn lie in the southeast. Mars is the bright one; Saturn is fainter and to Mars’ left. The Moon will reach First Quarter on the 12th.

Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory, Penticton.

 

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