Having just watched 'March of the Penguins', one particular moment cause me to reflect on a visit I once made in the late 80's to Edmonton, Canada, and how amazing it was to see the Northern Lights. My friends Karen and Dean were working and living in Northern Canada and my visit was at a time during which these were visible, something not terribly common for their area if I recall correctly. They had me go outside with them in the evening and we stood beneath the sky as green lights danced overhead. I have photos I took that night buried in some obscure box, but they could not come close to doing the actual experience justice. Fortunately, thanks to the internet, seeing them on video is a pretty reasonable compromise, and you can do so by clicking here or on the image shown above.
The layman's summation of this 'Aurora' is that the collision of solar winds with electro magnetic fields of the earth polor regions cause a reaction resulting in this phenomenon. Again, that's a relatively ignorant laymen's generalization. There's Plenty to read about this at Wikipedia.com. However it comes to be, seeing it was breathtaking and I'd recommend making an effort to do so as well, should you ever have the opportunity.