December 31, 2020: The gap from Jupiter to Saturn continues to widen. Find the planets for a short time low in the southwest after sunset before they set. Farther eastward Mars marches eastward in Pisces. The moon appears low in the east later during evening hours.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:18 a.m. CST; Sunset, 4:30 p.m. CST. Check local sources for sunrise and sunset times for your location.
The Jupiter – Saturn gap widens after the Great Conjunction that occurred 10 days ago. They are still close together in the sky, but they are 1.1° apart. That’s about 10 times larger than the close conjunction distance.
Begin looking for the planets about 45 minutes after sunset for about the next 15 minutes. The observing window continues to narrow. Jupiter sets 95 minutes after sunset.
The chart above shows the planets an hour after sunset when they are only 7° above the horizon. Find a spot with a clear horizon.
On photo above, made a little over a year ago, Jupiter was near the horizon, although not everybody has the luxury of a clear horizon. The planet was only 3° in altitude. We are not ready to make the last call to see the planets together in the evening sky, but this will occur soon.
Farther east, Mars is marching eastward in Pisces. In less than a week, it moves into Aries. The constellation’s brightest star, Hamal is identified on the chart above.
Hamal is not near the ecliptic. Mars passes the star later next month, at a separation less than 10°.
Use a binocular to spot Mars 1.0° to the lower left of Pi Piscium (π Psc on the chart) and 2.6° to the upper right of Omicron Piscium (ο Psc).
About three hours after sunset, the bright moon is low in the eastern sky.
Read about Mars during December.
One hour after sunset, Jupiter is over 7° in altitude, 1.1° to the upper left of Saturn. Jupiter is 0.9° to the lower left of σ Cap. Jupiter passes the star tomorrow. Mars is 84.6° of ecliptic longitude east of Jupiter. Tonight, the Red Planet passes 1.0° to the lower left of π Psc. Additionally, the planet is 2.6° to the upper right of ο Psc. Three hours after sunset, the moon (17.4d, 96%) – nearly 13° up in the east.
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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