Astronomy Picture of the Day

Explanation: One of the largest sunspot groups in recent years is now crossing the Sun. Labelled Active Region 2192, it has already thrown a powerful solar flare and has the potential to produce more. The featured video shows a time lapse sequence of the Sun in visible and ultraviolet light taken yesterday and incorporating the previous 48 hours. AR 2192, rotating in from the left, rivals Jupiter in size and is literally crackling with magnetic energy. The active Sun has caused some spectacular auroras in recent days, and energetic particles originating from AR 2192 may help continue them over the next week. Tomorrow, the Sun will appear unusual for even another reason: a partial solar eclipse will be visible before sunset from much of North America.