AAO image reference MISC 13. « Previous || Next »
Image and text © 1991-2002, Australian Astronomical Observatory, Photograph by David Malin.
As the earth spins beneath the stars they appear to move across the sky from east to west. However, if one looks in the direction of the celestial poles, the stars appear to circle a single point on the sky. This is the position of the earth's axis of rotation projected into space.
If this photograph had been made at either of the geographical poles, from the Arctic or in Antarctica, this point would directly overhead, and the axis of rotation would passing vertically through the camera. If the picture had been made from the equator, both the pivotal points would be seen 180 degrees apart, on the northern and southern horizons.
This picture was made from La Palma in the Canary Islands, off the coast of North Africa, so the pivotal point is about 30 degrees above the northern horizon, which is the geographical latitude of La Palma. In the northern sky there is also a bright star very close to the celestial pole. It is Polaris, the Pole star and is the shortest and brightest of the star trails seen here. When this picture was made, the sky over La Palma was affected by fine dust, blown from the Sahara Desert. this is why stars ner the horizon appear fainter and yellower than those higher in the sky. This same dust also reflected yellow light from sodium street lights on the island. A comparison image of the south celestial pole is here, and more information on star trail photography is here.
Related images
AAT 5. Star trails southwest of the AAT dome
AAT 6. Star trails around the south celestial pole
MISC 5. Dawn and evening twilights reflected in the AAT dome
MISC 6. Moonset into cloud over the Warrumbungle Range
MISC 7. Star trails around the AAT dome, after Pinatubo sunset
MISC 12. Orion's belt rising over the lights of Coonabarabran
MISC 14. South celestial pole star trails
MISC 15. North and South celestial poles star trails
MISC 18. The view to the north from Siding Spring
MISC 19. Sunset 'star' trail, the track of the setting sun