The Sky, November 20-26: Sun sets earlier on Thanksgiving than Christmas

Special to, November 21, 2023, 2023

Excerpts from weekly Sky&Telescope report.

First-quarter Moon passing Saturn, Nov. 19-20, 2023 MONDAY, NOVEMBER 20

■ First-quarter Moon (exact at 5:50 a.m. EST Monday morning). The Moon accompanies Saturn more closely than it did yesterday, as shown.

■ The tiny black shadow of Io crosses Jupiter’s face from 9:16 to 11:26 p.m. EST, moving across Jupiter from east to west. The side of Jupiter without the Great Red Spot will be facing us.


■ Algol should be at minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:55 p.m. EST; 7:55 p.m. PST. Algol takes several additional hours to fade and to rebrighten.


■ The east (left) side of the Great Square of Pegasus points down to the Moon this evening.

■ And the Moon itself forms a bigger, wide rectangle with (counting clockwise) Saturn three fists to its right, Fomalhaut below Saturn, and Beta Ceti left of Fomalhaut.


■ Does the Sun already seem to be setting about as early as it ever will? Correct. We’re still a month from the winter solstice — but the Sun sets its earliest around December 7th if you’re near latitude 40° north, and already the Sun sets within only about 2 minutes of that time.

A surprising result of this: The Sun actually sets a trace earlier on Thanksgiving than on Christmas — even though Christmas is famously close to solstice time!

This offset of earliest sunset from the solstice date is balanced out by the opposite happening at sunrise: The Sun doesn’t rise its latest until January 4th. Blame the tilt of Earth’s axis and the eccentricity of Earth’s orbit.


■ The Moon has moved on to the next giant planet, shining near Jupiter this evening and tomorrow evening as shown below.

Bright Moon passing Jupiter, Nov. 24-25, 2023

The bright waxing gibbous Moon passes Jupiter.


■ As the stars come out, the Cassiopeia W stands on end (its fainter end) high in the northeast. Watch Cas turn around to become a flattened M, even higher in the north, by late evening.


■ The Moon is full both this evening and tomorrow evening (because it’s exactly full at 4:16 a.m. Monday morning EST). This evening, the glary Moon is just 1° or 2° from the Pleiades for North America.

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