Astronomy Picture of the Day

Explanation: The Sun's surface keeps changing. The above movie shows how the Sun's surface oozes during a single hour. The Sun's photosphere has thousands of bumps called granules and usually a few dark depressions called sunspots. The above time-lapse movie centered on Sunspot 875 was taken in 2006 by the Vacuum Tower Telescope in the Canary Islands of Spain using adaptive optics to resolve details below 500 kilometers across. Each of the numerous granules is the size of an Earth continent, but much shorter lived. A granule slowly changes its shape over an hour, and can even completely disappear. Hot hydrogen gas rises in the bright center of a granule, and falls back into the Sun along a dark granule edge. The above movie and similar movies allows students and solar scientists to study how granules and sunspots evolve as well as how magnetic sunspot regions produce powerful solar flares. A few days ago, the largest sunspot group in recent years rotated into view.