Dec 7 had the earliest sunset of the year, even though the shortest day is on Dec 21.

This is because solar noon does not occur at clock time 12:00 p.m. Because of orbital eccentricity and axis inclination, it occurs earlier or later according to the Equation of Time.

E.g., for Philadelphia –
Dec 7: Sunrise 7:09 – Sunset 4:35 (9:26h), Solar noon 11:52
Dec 21: 7:18 – 4:38 (9:20h), 6m shorter, Solar noon 11:58, shifted by 6m
Sunset Dec 21 = 4:38 = 4:35 – 0:03 + 0:06
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en.wikipedia.org/wiki/Equation…