The Northern Lights – also called Aurora Borealis – are one of the most spectacular shows on earth and can frequently be seen in Iceland from September through April on clear and crisp nights. The Northern Lights occur high above the surface of the earth where the atmosphere has become extremely thin, in an altitude of 100-250 km. The Northern Lights exist in the outmost layer of the atmosphere. They are created by electrically charged particles that make the thin air shine, not unlike a fluorescent light. They can be seen in aurora belts that forms 20-25 degrees around the geomagnetic poles, both the north and the south.
If you are lucky, you might be able to see the northern lights from your bedroom window, but to increase your odds, many tour operators offer help to find the best location for viewing the northern lights.