Looks like 2012 has started rather well and we
were rewarded with two Auroras in a week (
January 16th and 22nd) visible from Southern
Coast of Australia.
The color of the aurora depends on which atom is
struck by solar wind, and the altitude of the
meeting.
Green - oxygen, up to 150 miles in altitude
Red - oxygen, above 150 miles in altitude
Blue - nitrogen, up to 60 miles in altitude
Purple/violet - nitrogen, above 60 miles in
altitude
( from