There’s a great time-lapse video of auroras over Norway on the Astronomy Picture of the Day site. http://apod.nasa.gov/apod/ap110328.html
The aurora borealis, or northern lights, are caused by electrically charged particles entering the atmosphere above the North Magnetic Pole and being excited into luminosity. The colors can be green, red, yellow, blue or violet, with green being the most common. In the southern hemisphere, the effect is called the aurora australis, or southern lights.
Your best chance of seeing an aurora is to look at the night sky after a period of sun spot activity while you are in the area between 60 and 72 degrees north or south latitudes. Since I have lived in places that are farther south, I had never seen an aurora until last year. There was a massive Coronal Mass Ejection that caused auroras to be seen much farther south than usual and I was lucky enough to finally view one. It was amazing, even though my view wasn’t perfect because of some intermittent clouds. The green color was much brighter than I had expected and I hadn’t known there was so much movement.
Auroras also occur on other planets. They’ve been observed on Venus, Mars, Jupiter, Saturn, Uranus and Neptune. They’ve also been seen on some of Jupiter’s moons.
I hope everyone will get to see an aurora at some time in their lives.