Red, green and blue in this aurora picture. The green is the standard aurora colour, but of course nothing is ever standard about these magnificent shows of nature!
Aurora turn red at higher altitudes as the solar winds excite atomic atoms to give off different light. It is effectively the same principle as how we create different colour neon lights. Shoutout to Don Pettit who basically invented space photography and took the time to write down tons of useful information like this to pass on to subsequent crews. The blue is from an impending sunrise on the horizon. When the sun comes, the aurora goes away, or at least is not visible anymore!

Allez ça faisait un moment, mais on ne se lasse pas du spectacle : une couche ? s’invite parfois au-dessus des flammèches des aurores australes, comme pour compléter le tableau (et le ?, ce sont les prémices d’un lever de soleil)

Credits: ESA/NASA-T. Pesquet larger image