!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> Streamline Training & Documentation: Spring Equinox 2009

Friday, March 20, 2009

Spring Equinox 2009

The image below actually dates to March 21, 2001, the day after that year's Spring equinox. The photographer, Joe Orman, wanted to capture the sun rising exactly due east, and had to wait until "Equinox + 1" to get his shot for the reason explained below the photo.

from NASA's Picture of the Day archive: "Twice a year, at the Spring and Fall equinox, the Sun rises due east. In an emphatic demonstration of this celestial alignment, photographer Joe Orman recorded this inspiring image of the Sun rising exactly along the east-west oriented Western Canal, in Tempe, Arizona, USA. But he waited until March 21st, one day after the northern Spring equinox in 2001, to photograph the striking view. Why was the rising Sun due east one day after the equinox? At Tempe's latitude the Sun rises at an angle, arcing southward as it climbs above the horizon. Because the distant mountains hide the true horizon, the Sun shifts slightly southward by the time it clears the mountain tops. Waiting 24 hours allowed the Sun to rise just north of east and arc back to an exactly eastern alignment for the photo."