The Orkney International Science Festival

THE SCIENCE OF THE SUN, Orkney Theatre, KGS, Kirkwall, September 9th

By Eamonn Keyes

The Sun’s heat and light is vital for life on Earth – but it also generates ‘space weather’ that can damage satellites and endanger astronauts. Dr Karen Meyer of Dundee University describes the huge temperatures of the Sun’s atmosphere and the massive eruptions of energy that sometimes burst from it; and how mathematics can shed light on some of its mysteries.

In Orkney the Sun has the status of the average rowdy tourist -showing up only during the short summer, not staying for very long and making sure few people get any meaningful sleep at night during that period that it’s around.

However, this year’s Science Festival has highlighted it via The SUN installation in St Magnus Cathedral and several events, both directly and indirectly.

The Sun is important to us for several reasons.

Firstly, without it we wouldn’t be here at all, as it is responsible for Earth’s creation and ongoing development, which includes us as temporary tenants, and one day in the far future it will likely be responsible for the destruction of the Solar System when it runs out of hydrogen, becomes a red giant which will likely swallow us up before collapsing inward, exploding and throwing the remaining planets into space after roasting them and drenching them with huge amounts of radiation that even Factor 5 million sunscreen and a duffle coat wouldn’t stop.  But, seeing as that’s probably in around 5 billion years’ time, I wouldn’t go cancelling Netflix just yet.

It’s important to realise just what the Sun actually is, and what it does. It’s just not there for nice days out and a memorable holiday tan.

It’s actually a star, merely the closest one to us, and not a particularly memorable one in the pantheon of stars at that. However, what it is good at is producing energy, huge amounts of it, in conditions we cannot even begin to imagine.

Dr Karen Meyer of Dundee University is not an astronomer but a mathematician, and she has used the field of Applied Mathematics in solar studies, such as in the simulation and observation of the Sun’s magnetic field, particularly modelling the decay of solar active regions, modelling coronal jets and tracking sunspots.

This has become more important as science has realised that the weather on the Sun can have huge implications on what we experience on Earth, leading to the birth of Spaceweather.

Go see for yourself at Spaceweather.com which covers what’s happening on the Sun as well an information on the aurora, satellites, meteors, asteroids etc.

Solar outbursts can lead to effects on telecommunications, increasing drag on orbiting satellites and exposing astronauts to dangerous radiation.

In 1989 a solar flare and coronal mass ejection (CME) of solar material equivalent to many thousands of nuclear bombs hit Earth, plunging the entire province of Quebec, Canada, into an electrical blackout that lasted 12 hours, as it burned out several transformers.

Karen took us on a journey through the vast variation in temperatures on the sun, from 15 million degrees Celsius at the core to 6,100 degrees Celsius at the surface (photosphere) which is the bit we see, and eventually to the 1 million degrees Celsius of the corona, the sun’s atmosphere we see shining during eclipses.

We learned of the Solar cycle of 11 years, indicated by sunspot activity, with many sunspots being bigger than Earth. Falls in sunspot activity for prolonged periods indicate reduced solar activity, and can lead to colder periods on Earth, such as mini-ice ages.

The seething weather of the Sun is driven by the nuclear fusion of its core, where hydrogen is fused into helium, and the huge magnetic field it possesses. This produces the loops and eventually the CMEs that drive the Solar Wind, blasting outwards throughout the solar system. In turn, it is only the Earth’s magnetic field that protects us from it, taking the deadly charged particles down to the North and South Poles where they produce the Aurora as they collide with Earth’s atmosphere in a glorious display. If not for our magnetic field, produced by the Earth’s iron core, there would be no life on our planet.

Due to the Sun’s distance from the Earth, 150,000 km or 93 million miles in old money, the light from it takes 8 minutes to reach us. To show this in real terms, if you set off in your car at 70 mph all the way it’d take you 150 years to reach it, even if you stopped for fuel and a comfort break at Venus and Mercury.

However, due to the activity of the Sun, the photon that we’d see arriving 8 minutes after it left the Sun has also taken over 100,000 years to get from the Sun’s core to its surface because of collisions on the way. The Sun is a very busy place.

This was a very entertaining Public Astronomy event, supplemented by an opportunity to view the Sun via a special solar telescope outside St. Magnus Cathedral, but unfortunately by mid-afternoon the Sun had decided to go back among the clouds.

Karen answered the many audience questions as best she could, given the complexity of some, and ended the event by making available a large haul of free posters, hand-outs and images of the Sun, all of which were very useful as well as being very striking.

I hope some are now adorning the walls of children and firing up their imagination with their wonderful imagery, as that is one of the main points of these events, to inspire our future scientists in every field. I’ve even dug out my own small solar telescope.