Astronomy Picture of the Day

Explanation: Sometimes, after your eyes adapt to the dark, a spectacular sky appears. In this case, a picturesque lake lies in front of you, beautiful green aurorae flap high above you, brilliant stars shine far in the distance, and a brilliant moon shines just ahead of you. This digitally fused panorama was captured earlier this month from Yellowknife, Northwest Territories, Canada, and includes the Pleiades open cluster of stars just to the upper right of the Moon. Since aurorae are ultimately started by solar activity, this current flurry of auroras is somewhat surprising, given the historic lack of sunspots and other activity on the Sun over the past two years. This time of year is known as aurora season, however, for noted average increases in auroras. The reason for the yearly increase is not known for sure, but possibly relates to the tilt of the Earth creating a more easily traversable connection between the Earth's magnetic field and the magnetic field of the Sun's changing wind streams.