Thanks. Yes people tend to think it just warms or cools a photo. Which it does off course however it does that by shifting down or up the wavelengths of light captured. In the case of auroras it is such a dramatic shift as you don't have the broad spectrum of light you normally see in the day (or almost any other white light source), but some very narrow bands of specific colors. I hope you get the chance to see it one day ; its quite a special thing to witness. Are you based in Quebec? I would love to spend some time over there.