Astronomy Picture of the Day

Explanation: Fix your camera to a tripod and you can record graceful trails traced by the stars as planet Earth rotates on its axis. If the tripod is set up at ESO's La Silla Observatory, high in the Atacama desert of Chile, your star trails would look something like this. Spanning about 4 hours on the night of January 24, the image is actually a composite of 250 consecutive 1-minute exposures, looking toward the north. The North Celestial Pole, at the centre of the star trail arcs, is just below the horizon in this southern hemisphere perspective. In the foreground, the polished 15-metre diameter dish antenna of the Swedish-ESO Submillimetre Telescope (now decommissioned) shows star trails toward the south by reflection. Sweeping around the South Celestial Pole, the distorted arcs of those stars appear underneath the southern horizon in the focusing dish's inverted view. Right of the dish is the dome of the observatory's 3.6 metre telescope, home to the planet hunting HARPS spectrograph.