Shape of the Setting Sun

December 06, 2013


Photographer: Hans Juergen Heyen 
Summary Authors: Hans Juergen Heyen; Jim Foster

The photo sequence above shows the Sun setting over the Wadden Sea, Germany, on September 5, 2013. Flattening of the solar disk (and lunar disk too) at sunset and sunrise occurs as a result of atmospheric refraction. The solar disk is big enough so that light from its lower portion passes through somewhat more of the atmosphere than does the upper portion. Therefore, the bottom is refracted upwards by a slightly greater amount than is the case for the top, leading to the squished appearance. On the bottom left photo, note the small horse-drawn cart in the mid-ground – used to transport tourists at low tide from Neuwerk Island to the mainland town of Cuxhaven. Photos taken from the window of my hotel in Cuxhaven on September 5, 2013.

Photo details: Camera Model: Canon EOS 600D; Lens: EF300mm f/4L IS USM; Focal Length: 300mm & 420mm; Aperture: f/5.0 & f/9.0; Exposure Time: 0.0025 s (1/400) & 0.0016 s (1/640).