December 16, 2020: The crescent moon joins Jupiter and Saturn as a prelude to the Great Conjunction in 5 evenings. The moon is visible below the planets. Mars is in the southeast after sunset.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:12 a.m. CST; Sunset, 4:21 p.m. CST. Check local sources for sunrise and sunset times for your location.
Just five days before the Great Conjunction of Jupiter and Saturn, the moon makes a dramatic appearance with the converging planets. From about 45 minutes after sunset to about 90 minutes after the sun’s nightly disappearance, the moon can be seen below the planet pair.
Not until March 17, 2080, does the moon appear near a very close grouping of Jupiter and Saturn. The moon passes Jupiter and Saturn every month, but the two planets are near each other every 19.6 years. Other Great Conjunctions occur in 2040 and 2060, but the conjunction distance is over 1°.
Jupiter sets at about 7 p.m. CST in Chicago, Illinois, about 2.5 hours after sunset for other locations.
The crescent moon is only 7% illuminated and over 5° below the bright planet Jupiter. Saturn is 0.5° to the upper left of the Jovian Giant. The separation of the two planets is about the same as the moon’s width in the sky.
The Great Conjunction occurs in 5 evenings! Jupiter continues to slowly close the gap to Saturn for this once-in-a-generation meeting of the two planets.
Photographers can capture the trio together with time exposures ranging from a few seconds to about 10 seconds on a tripod-mounted camera. The longer exposures will capture earthshine, the glow of reflected sunlight from Earth’s features that gently illuminates the lunar night.
Farther east, bright Mars is about halfway up in the east. It is marching eastward in front of the starry background of Pisces. In the starfield, the Red Planet is 1.5° to the upper left of Zeta Piscium (ζ Psc on the chart) and 3.7° to the lower left of Epsilon Piscium (ε Psc).
The Red Planet is in the south about three hours after sunset. It sets in the west over 5 hours before sunrise.
Read about Mars during December.
Detailed note: Jupiter is 16° up in the southwest, 0.5° to the lower right of Saturn. Great Conjunction Countdown: 5 days. One after sunset, the crescent moon (2.3d, 7%) is 5.4° below Jupiter. Farther east, Mars (m = −0.6) is over 45° up in the southeast. In the starfield, the Red Planet is 1.5° to the upper left of ζ Psc and 3.7° to the lower left of ε Psc.
For more about the Great Conjunction, read our feature article. This is the closest Jupiter – Saturn conjunction since 1623.
Read more about the planets during December.
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