The tail of Comet Halley on 9 December, 1985
AAO image reference UKS 39.    « Previous || Next »

The tail of Comet Halley on 9 December, 1985
Top left is NE. Image width is about 3 degrees.
© 2010, Australian Astronomical Observatory. Photograph by David Malin from UK Schmidt Telescope plates.

Almost all the colour pictures in these pages have been made by combining three black and white photographs taken in red, blue and green light. At the time, this offered many advantages over colour film, one of them the ability to copy the original glass negatives to high contrast using a photographic amplification technique to reveal faint features. However, nowadays, such images are made using solid state detectors such as CCDs.

Most objects are very distant and plates taken years apart show little change; however Halley's Comet moved rapidly through the solar system towards the sun and as the telescope followed its motion the background stars were recorded as coloured streaks, their length corresponding to the exposure times, (25, 25 and 30 minutes). The diffuse coma is tinged blue by the action of sunlight on gases evaporated from the icy nucleus, leaving behind tiny dust grains as a faint yellow tail shining by reflected sunlight. This is better seen on the photograph made on the same night, using the Anglo-Australian Telescope (AAT 46).

Related images, other comets
AAT 46.    Halley's Comet, December, 1985
AAT 117.  Halley's Comet, April 9-10, 1986 (AAT image)
UKS 19.   Halley's Comet on 12 March, 1986
UKS 19a  Features in the dust tail of Comet Halley, 12 March, 1986
UKS 33.   Comet Hyukatake, March, 1996
UKS 34.   Halley's Comet on April 9-10, 1986
MISC 20. Comet Halley hanging in the Milky Way in 1986.

For details of object position and photographic exposure, search technical table by UKS reference number.

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Updated by David Malin, 2010, July 25