Waterfall and Circumpolar Stars

May 29, 2011

Photographer: Ralph O. ClementsRalph's website
Summary Author: Ralph O. Clements; Jim Foster

The long exposure image above shows an unnamed waterfall on Falling Branch, in southwestern Virginia, illuminated by the full Moon. It was taken on the night of March 19, 2011 when the Moon was at perigee -- its apparent size was as big as it's been in about the last 20 years. Falling Branch is a three mile (5 km) long stream that falls roughly 600 ft (183 m) over its course -- it eventually drains into the South Fork of the Roanoke River. The waterfall seen here is about 20 ft (6 m) high. My camera is facing north. Both the waterfall and circumpolar stars of the Northern Hemisphere are shown on this 30 second exposure. Polaris (North Star) is the bright spot (actually a very tight circle) near the center of the star trails. It's offset 0.8 degrees from the true celestial pole. An airplane can be seen passing through the lower edge of the star field (dotted line). To see a short time lapse video showing moonlight spreading over this scene click here.

Photo details: Image is a composite of 117 images, each a 30 second exposure; Canon T1i DSLR camera in manual mode; taken at F5.6 with a 35-70mm zoom lens set on 35 mm. I chose a high ISO equivalent of 3200 to try and capture the stars, though they're somewhat overwhelmed by the very bright moonlight.