Hi Beren, I caught the Northern Lights on a trip to Tromsø in Northern Norway and they were spectacular!
Here's a photo I took there:
Canon EOS 5D with 35mm f1.4L at f2.0 for 15 seconds, 400 ISO
I'd like to claim it was all my own work, but I was lucky enough to meet up with a well-known Aurora photographer called Kjetil Skogli, who also happens to be a member of this forum, under the name Neptun. Kjetil runs Aurora Guided Tours for small groups and they're a wonderful experience, especially if you're keen to take some photos. He gave me some great advice, and has some useful information at his website here:
If you're ever visiting Norway, I highly recommend it!
If it's really cold, you'll also need to watch out for your batteries and he gave some good tips in the forum in this post:
http://www.cameralabs.com/forum/viewtop ... highlight=