Comet Holmes changes in color and size
In late October I observed Comet Holmes through the 20cm
refractor. It was brightening and showed a beautiful golden-yellow coma.
The central condensation was glowing as white as snow and a perfectly stellar
nucleus was vividly seen near the middle of the condensation. The 20'-wide
coma was enveloped by very faint, extensive purplish gas. Photos by the
60cm reflector also showed a vivid golden color.
About two weeks later the comet was brighter and its coma
grew to nearly 30' in diameter, almost as large as a full moon. The colors
of the coma changed, too, perhaps due to temperature changes during the
brightening, from gold to bright blue. Visually it looks white but greenish
blue in photographs resembling a traffic light. These changes have occurred
over a short period of about 10 days. In the next diary entry I will describe
the appearance of the comet which has began showing a tail.
17P/Holmes
5-minute exposure from 20:00, October 29, 2007
60cm f/3.5 reflector, ISO 800 film
17P/Holmes
5-minute exposure from 2:00, November 11, 2007
60cm f/3.5 reflector, ISO 800 film