Astronaut Matthew Dominick captured from ISS amazing pink colored aurora. Green is the most common color seen from the ground and is produced when charged particles collide with oxygen molecules at altitudes of 100-300km. Occasionally, the lower edge of an aurora will have a pink or dark red fringe, which is produced by nitrogen molecules at altitudes of around 100km. Higher in the atmosphere at altitudes of 300-400km, collisions with oxygen atoms produce red auroras.
Reference: Matthew Dominick’s Tweet
See earthview photo gallery: LiVEARTH