AAO image reference UKS 19. « Previous || Next »
Top left is NE. Image width is about 4 degrees
Image and text © 1986-2010, Australian Astronomical Observatory
Photograph from UK Schmidt plates by David Malin.
To those prepared to leave their brightly lit suburbs and seek dark skies, Comet Halley was there to be enjoyed in late 1985 and the first few months of 1986, especially in the southern hemisphere. The warming action of sunlight on the tiny nucleus of the comet evaporates volatile materials from its surface which expand rapidly in the vacuum of space, producing the large coma. Solar radiation pressure sweeps back this tenuous cloud into the typical comet shape. Emerging from the coma, two distinct tails can be seen. The blue tail is highly structured and is primarily due to volatile molecules such as water, carbon dioxide and carbon monoxide dissociated by ultraviolet sunlight, fluorescing in the blue colour of the cyanogen radical, while the faint yellow streak is sunlight reflected from dust particles liberated from the nucleus along with the volatile materials.
Related images, other comets
AAT 46. Halley's Comet, December, 1985
AAT 117. Halley's Comet, April 9-10, 1986 (AAT image)
UKS 19a. Comet Halley, monochrome, showing detail in the tail
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.
B&W image Features in the dust tail of Comet Halley, 12 March, 1986
For details of object position and photographic exposure, search technical table by UKS reference number.