The Magnetic Sun

“The Magnetic Sun.” Dr Alice Courvoisier was the title of the August 2008 Cambridge Astronomy Association talk. 

A diagram of the sun explained each named part of the Sun including the photosphere, chromosphere, filament, convective zone, radiative zone and prominence.

It was also explained to us that the solar material in the Sun is a plasma and so conducts electricity.

The lecture included of course sunspots, and it was interesting to find out that the actual recording of sunspots did not begin until 1610. William Herschel thought that sunspots were openings in the Suns atmosphere.

The centre of a sunspot is called an Umbra whilst the outer part is called the Penumbra. The Umbra appears darker as it’s cooler than the other parts. We were also told that sunspots appear in pairs which have opposite polarity. There is an 11 year sunspot cycle and the polarity of the sunspots also reverses after 11 years.

The talk then asked the question can we predict solar activity? This section ended by quoting “At the moment there appear to be too many uncertainties in the current solar cycle models to allow for sound predictions”, which was taken from a Nature article.

We were told that solar winds are when the Sun expels a million ton of particles which are threaded by magnetic fields.

Solar activity can also cause problems for us on the Earth, as geomagnetic storms induced by solar events can interrupt radio, satellites, cause power cuts and damage pipelines. . In March 1989, 6 million Canadians lost power for 9 hours because of the Sun’s magnetic activity.

Overall this was an interesting talk that taught me more about the Sun than I knew.

Alice first came to the UK to follow a masters course at Cambridge University in 1999. Then, after a two year break teaching physics in Madagascar, she came back to do my PhD in the Department of Applied Mathematics at Leeds University, which she completed in 2006. Alice is currently working as a post-doctoral research associate in Leeds; where her main interest is trying to understand the origin on large-scale magnetism in astrophysical bodies.

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