Photo by Sheila Holloway (thanks Sheila!)

Dear Readers, the Northern Lights appeared over East Finchley last night, and yet again I have managed to miss them (being sat on the sofa with icepacks on both legs, quite a performance). But how lovely to see all the photographs today – the one above is from Bounds Green/Muswell Hill, just up the road from me, and my Facebook feed today is full of photos from all over the southern UK. They’ll have to rename the Northern Lights to the North London Lights at this rate. I was planning on a trip to Iceland to see them at some point, but it sounds as if I could see them from the upstairs window.

But why are they appearing so far south? Normally, Auroras (Borealis in the north, Australis in the south) are seen at the poles, and in fact occur at the poles of other planets too – look at this amazing  photograph of the Aurora on Jupiter, published by Nasa and taken  by the Hubble Telescope.

Auroras are caused by the ‘solar wind’, usually defined as an emission of charged particles by the sun. When these bounce off of the gases in the Earth’s atmosphere, they release light at various wavelengths which form the colourful display. Normally these displays are limited to the poles, but the sun goes through cycles of activity which last for about eleven years. During the height of the cycle, gigantic geomagnetic storms occur on the surface of the sun, forming sunspots and causing a massive increase in the ‘solar wind’. Instead of just bouncing off the poles, the ‘wind’ forms a much broader band, bouncing off the atmosphere above a much wider range of countries. Here’s an image from the last ‘big’ aurora, in May this year, from Stirling in Scotland.

The aurora in May seen over Stirling in Scotland (Photo by Richard Sutcliffe at Aurora borealis © Richard Sutcliffe :: Geograph Britain and Ireland

And so, will this continue? The sun is currently at its peak, but there might be a few more opportunities before things return to ‘normal’. In the UK you can subscribe to Aurora Watch, which will give you a warning if an aurora is expected. I’d love to know if you’ve been able to see it! Has there been similar activity in the southern hemisphere, I wonder? Let me know in the comments!