Guest blog: Sarah Reay, British Geological Survey

Many people in the UK were treated to a fine display of the northern lights (aurora borealis) on Sunday night. This was seen widely throughout Scotland and the north of England. There is a chance for further auroral displays tonight or tomorrow night if we are lucky.

The Northern Lights are a result of a geomagnetic storm. These storms are short-lived periods of high geomagnetic activity where the Earth’s magnetic field changes very quickly and strong electric currents flow high in the atmosphere.

The geomagnetic storm is a consequence of activity on the surface of the Sun. Occasionally there are large explosions on the Sun, and huge amounts of charged particles are thrown out into space. These particles sometimes travel towards Earth where they are captured by the Earth’s magnetic field and guided towards the geomagnetic polar regions. On their way down these particles are slowed down by Earth’s atmosphere, which acts as a shield. These charged particles collide with gas molecules in the atmosphere. The energy released in these collisions is given off as light.

Geomagnetic storms follow the 11-year solar cycle. As we are heading towards the next solar maximum, due in 2013, the chance of big magnetic storms is on the increase. On average you might expect to see aurora in the far north of Scotland every few months, but less often as you travel further south.

To view the Northern Lights you are best finding a dark place away from street lights. You will need a cloud-free sky. In general, look to the north although it could be overhead or elsewhere. For your best chance of sighting an aurora, try to look during the hours around local midnight (22:00-02:00). However geomagnetic activity can happen at any time!

You can sign-up to receive alerts from the British Geological Survey when there is a chance for aurora activity. Unfortunately cloud is predicted for most of the UK tonight, but there is a much better chance for Wednesday night onwards. Keep an eye on the Met Office forecasts for the latest information.

* Many thanks to Sarah Reay of the British Geological Survey for the above guest blog. As a side note, people may be interested to know that solar storms can have other impacts on our planet – such as affecting telecommunication systems. The Met Office is developing a space weather forecasting system to give early warnings of events. As part of this, we are working in collaboration with the US’s National Oceanic and Atmospheric Administration (NOAA) to develop the service.