2020, December 17: Jupiter, Saturn, and Crescent Moon

December 17, 2020: Jupiter and Saturn appear again with the crescent moon although the moon’s spacing is larger than last night.  Jupiter continues to close in on Saturn.  Great Conjunction Countdown: 4 days!

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:13 a.m. CST; Sunset, 4:21 p.m. CST.  Check local sources for sunrise and sunset times for your location.

Jupiter slowly closes the gap to Saturn.  Find them in the southwest, beginning about 45 minutes after sunset.  Jupiter is the bright “star” low in the sky.  Saturn is to the upper left of its brighter companion. 

The planets are closer in the sky than the moon’s apparent size.  Extend a pinky finger to arm’s length.  The tip of your finger covers both planets.  It’s not often that two planets appear this close in the sky.

Great Conjunction Countdown: 4 days!

This evening the crescent moon, that is 13% illuminated, is to the upper left of Jupiter and Saturn.

Farther east, Mars marches eastward in front of the stars of Pisces.  It is moving away from Zeta Piscium (ζ Psc on the chart) and Epsilon Piscium (ε Psc).

The Red Planet is over halfway up in the southeast as night falls.  The planet is south about three hours after sunset.  It sets in the west a few hours after midnight and over five hours before sunrise.

Read about Mars during December.

Detailed note: Forty-five minutes after sunset, Jupiter is nearly 16° up in the southwest, 0.4° to the lower right of Saturn. Great Conjunction Countdown: 4 days. The lunar crescent (3.3d, 13%) is over 10° to the upper left of Jupiter. As the sky darkens further, Mars is over 47° up in the southeast, 1.8° to the upper left of ζ Psc and 4.0° 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.