Astronomy Picture of the Day

Explanation: Have you ever seen an aurora? Aurorae are occurring again with increasing frequency. With the Sun peaking at its eleven year maximum in aurora-triggering activity, it is exhibiting a greater abundance of sunspots, flares, and coronal mass ejections. Solar activity like this typically expels charged particles into the Solar System, some of which impact Earth's magnetosphere and trigger Earthly aurorae. In late 2010, the above timelapse displays of picturesque aurorae were captured above Tromsø, Norway. Curtains of auroral light, usually green, flow, shimmer and dance as energetic particles fall toward the Earth and excite atoms of air high up in the Earth's atmosphere. There may even be opportunities to see aurorae tonight, as recent solar explosions have triggered numerous aurora sightings over the past few days.