Hi! I wonder what makes the Aurora colors. This is what I naively believe I know: Charged particles are ejected from the Sun and hits our protective magnetic field eight minutes later. At the poles, the magnetic flux density, B, is the greatest. Particles coming from the Sun are intercepted by B and gyrates around the lines of force. Close to the poles B is the greatest, which means a higher radial frequency of the particles. This excites the elements of our air (mainly Nitrogen and Oxygen). The ejected particles excites them in such a way that when they first hit them, they are excited but later on they lose this excited energy and sends out the difference according to hf (=hc/λ) which is the Aurora light we see. The Aurora is however not uniform in color. And gasous vacuum tubes, where air has leaked inside, glows pink. I therefore wonder two things: 1) Are the diffent colors (red and green, as far as I understand) due to Nitrogen and Oxygen excitation accordig to above? 2) How come the colors are separated in the sky (and not pink or some mixture)? This obviously means that there is some kind of gradient or separate distribution in the sky while ordinary air seems to be quite homogenous. On the other hand I have heard something about an ionsphere up there too... Best regards, Roger PS Please give me a physical explanation and not too much of a layman explanation.