Astronomy Picture of the Day

Explanation: The snow capped Teide volcano is reflected in a pool of water in this nearly symmetric night sky view from the Canary Island Tenerife. Bright north star Polaris stands above the peak in an exposure that also captures the brilliant trail of a polar orbiting Iridium satellite. Of course, with the camera fixed to a tripod, the stars themselves produce concentric trails in long exposures, a reflection of the Earth's rotation around its axis. In fact, you can add about 4.5 hours of exposure time to this image by just sliding your cursor over the picture. Large astronomical observatories also take advantage of the calm Canary Island sky.