Razor's Edge, Best of Cross Country Trip 800x600

The timing of sunset varies with the time of year and the latitude of the location from which it is viewed. The precise local time of sunset also depends upon each location's precise longitude within a given time zone. Small daily changes and noticable semi-annual changes in timing of sunset are driven by the axial tilt of Earth, the spherical shape of the Earth, and the planet's movement in its annual orbit around the sun. Some apparent anomalies exist however, the main one caused by the Earth's axial tilt and the Earth's elliptical orbit. In the Northern Hemisphere, the earliest sunset does not fall on the winter solstice around December 21, but instead it occurs earlier in December. Likewise, the latest sunset does not fall on the summer solstice around June 21, but instead it happens later in June or in early July, depending on one's latitude. The same phenomenon exists in the Southern Hemisphere except with the respective dates being some time before June 21 in winter and some time after December 21 in summer, possibly in January of the following year. For one or two weeks surrounding both solstices, both sunrise and sunset get slightly later or earlier each day. Even on the equator, sunrise and sunset shift several minutes back and forth through the year, along with solar noon. This effect is plotted by an analemma.

 
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