Baltimore's earliest sunset of the year arrives Friday at 4:43 p.m.

The days are still getting “shorter” as we approach the winter solstice Dec. 21, but after Friday, sunsets begin arriving later in Baltimore for the first time since late June.

The sun will set at 4:43 p.m. Friday.

Sunset is at about that same time each afternoon for the first two weeks of December. But Friday’s is the earliest by a matter of seconds.

The earliest sunset doesn’t come on the winter solstice because human timekeeping cannot align perfectly with the ever-changing solar clock.

Because the Earth’s orbit is elliptical, the length of a day is not usually 24 hours exactly.

And because its axis is tilted, the orientation of the line that divides day and night on the planet at any given moment also changes throughout the year. That means the timing of sunrises and sunsets always varies by latitude — this time of year, the farther north, the earlier the sunset.

The timing also varies by longitude, with time zones spanning hundreds of miles — the farther east, the earlier the sunset.

In Baltimore, the sun will set after 5 p.m. starting Jan. 8, after 6 p.m. by March 3, and after 7 p.m. by March 10 (because of the shift to daylight saving time).

The latest sunset of the year comes at 8:37 p.m. June 27-28.

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