Aurorae Australis
AAO image reference MISC 8.     « Previous || Next »

Aurorae Australis
Image and text © 1989-2002, Australian Astronomical Observatory, Photograph by David Malin.

The Sun has a cycle of activity that builds to a maximum about every eleven years. For a year or so around solar maximum the number and size of sunspots increases and energetic, electrically charged particles are ejected from the surface of the sun in much greater numbers than at other times. They take several days to travel as far as the earth and when they arrive, the earth's magnetic field channels them to high latitudes around the north and south poles. There they enter the upper atmosphere and produce the beautiful aurorae seen in both hemispheres, usually about 30 degrees from the poles, the Aurora Australis in the south, Aurora Borealis in the north.

Only at times of extreme solar activity are aurorae seen at lower latitudes such as Siding Spring Observatory, which is about 60 degrees from the pole (30 degrees south latitude). However one such occasion occured when the sun was particularly active in October 1989, when this picture was taken. The southern half of the sky turned a uniform bright red for most of one night and a little of the next. This picture was taken looking due south where the aurora was most intense. In the foreground is a V-shaped support for a telescope designed to point to the south celestial pole, around which the stars seem to rotate.

More star-trail images
AAT 5.     Star trails southwest of the AAT dome
AAT 6.     Star trails around the south celestial pole
MISC 7.   Pinatubo sunset and star trails around the AAT dome
MISC 11. Orion star colours, step-focus technique
MISC 12. Orion's belt rising over the lights of Coonabarabran
MISC 13. North celestial pole star trails
MISC 14. South celestial pole star trails
MISC 15. North and South celestial poles star trails
MISC 16. Southern Cross and Pointers, star colours - step-focus technique, long trails
MISC 17. Pinatubo dust colours the twilight
MISC 18. The view to the north from Siding Spring
MISC 19. Sunset 'star' trail, the track of the setting sun
MISC 22  The AAT dome from the Director's Cottage.
MISC 23  Southern Cross and Pointers, star colours - step-focus technique, short trails

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Updated by David Malin, 2012, March 17