Patterned Frost on Lens Cover

June 07, 2008

060708 copy

Provided and copyright by: Larry McNish, Royal Astronomical Society of Canada (Calgary)
Summary author: Larry McNish 

High humidity, fog and dew often plague observers using telescopic equipment and cameras to view the night sky. On the night of August 28, 2007, we observed the total lunar eclipse from 2:00 a.m. to 7:00 a.m. local time at the University of Calgary's Rothney Astrophysical Observatory, near Calgary, Alberta, Canada. By sunrise, the eclipse was over and the cold, wet telescopes were being dried off and packed away. The picture above is of a 14 inch (35 cm) diameter, black metal cover for one of the telescope's objective lens. It had lain undisturbed for several hours outdoors on a table, and the dew that collected on it froze as the temperature dropped to the freezing point, just before dawn. The floral pattern of the ice crystals was created naturally during this process.