Astronomy Picture of Day: 11 Hour Star Trails# Astronomy - 天文
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11 Hour Star Trails
Credit & Copyright: Josch Hambsch
Explanation: Fix your camera to a tripod, lock the shutter open, and you can
make an image of star trails - graceful concentric arcs traced by the stars
as planet Earth rotates on its axis. Of course, the length of the star
trails will depend on the exposure time. While exposures lasting just five
minutes produce a significant arc, in about 12 hours a given star would
trace out half a circle. But in any long exposure, the background glow from
Credit & Copyright: Josch Hambsch
Explanation: Fix your camera to a tripod, lock the shutter open, and you can
make an image of star trails - graceful concentric arcs traced by the stars
as planet Earth rotates on its axis. Of course, the length of the star
trails will depend on the exposure time. While exposures lasting just five
minutes produce a significant arc, in about 12 hours a given star would
trace out half a circle. But in any long exposure, the background glow from
