Eclecticus

cwnl:

Celestial Footprints: Star trails around the south celestial pole

By pointing a camera towards the south (or to the north in the northern hemisphere) at night, we can record the paths of stars which never set. They appear to circle the apparent position of the Earth’s axis of rotation projected on the sky. The elevation of this position above the local horizon indicates our local geographical latitude, about 30 degrees south at Siding Spring. The angle swept out by the arcs is an indication of the exposure time, which in this case was about 10.5 hours on 400 ISO colour film, using a Hasselblad camera which has a square format, seen in full here. This kind of long exposure is only possible from an extremely dark site such as Siding Spring Observatory, which is the location of the Anglo-Australian Telescope, whose building dominates the foreground.

Credit: AAO