Astronomy Picture of the Day

Explanation: Sometimes, after your eyes adapt to the dark, a spectacular sky appears. Such was the case earlier this month when one of the largest auroral displays in recent years appeared over northern locations like the border between Norway and Russia. Pictured in the above time-lapse movie, aurorae flow over snow covered landscapes, trees, clouds, mountains and lakes found near Kirkenes, Norway. Many times the aurorae are green, as high energy particles strike the Earth's atmosphere, causing the air to glow as electrons recombine with their oxygen hosts. Other colours are occasionally noticeable as atmospheric nitrogen also becomes affected. In later sequences the Moon and rising stars are also visible. With the Sun expected to become ever more active over the next few years, there may be many opportunities to see similarly spectacular aurorae personally, even from areas much closer to the equator.