Northern lights in Tromsø, displaying the collisions between electrically charged particles from the sun which penetrate the earth’s magnetic shield and strike atoms and molecules in our atmosphere. Collisions excite the atoms causing electrons to move to higher-energy orbits, further away from the nucleus. When electrons move back to lower-energy orbits, they release particles of light called photons which form the aurora. The green color is produced by collisions with oxygen, purple colors are produced by collisions with nitrogen.
Description by Rita Nogherotto, as it first appeared on imaggeo.egu.eu.
Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.
