Astronomy Picture of the Day

Explanation: It was one of the most memorable auroras of the season. There was green light, red light, and sometimes a mixture of the two. There were multiple rays, distinct curtains, and even an auroral corona. It took up so much of the sky. In the background were stars too numerous to count, in the foreground a friend trying to image the same sight. The scene was captured with a fisheye lens around and above Tromsø, Norway, last month. With the Sun becoming more active, next year might bring even more spectacular aurora.