December 8, 2011
What is the year's earliest sunset time for the Chicago area?
—Barbara Linskey, Mt. Prospect
The city is currently in its period of earliest sunsets. According to calculations from the U.S. Naval Observatory, Chicago's earliest sunset is 4:20 p.m. from Dec. 2-15. Beyond that date, sunsets slowly increase to 4:29 p.m. by Dec. 31. Despite the later sunsets, the city's least amount of daylight occurs around the Dec. 22 winter solstice because of later sunrises. In fact, city sunrises will be at their latest time of 7:18 a.m. from Dec. 28 to Jan. 10. According to astronomer Dan Joyce from Triton College's Cernan Space Center, these discrepancies are related to the eccentricity of the Earth's orbit around the sun and the proximity of the solstice to the Jan. 4 perihelion, the point when the Earth is closest to the sun.
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