December 30, 2020: Nearly 10 evenings after their Great Conjunction, Jupiter opens a gap to Saturn that is 1.0°. Look for the two planets low in the southwest after sunset. The star Castor rises at sunset. As the sky darkens, Mars is high in the southeast in front of the stars of Pisces.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:18 a.m. CST; Sunset, 4:29 p.m. CST. Check local sources for sunrise and sunset times for your location.
Jupiter and Saturn are fading into the sun’s twilight. We’re not ready to make the “last call” to see them in the evening after sunset, although they are becoming more difficult to see because of terrestrial obstructions and their low altitude in the sky.
Begin looking for them about 45 minutes after sunset. Jupiter sets about an hour after they first become visible. The observing window lasts about 30 minutes, as the planets appear lower in the sky before they set.
This evening the star Castor – one of the Gemini Twins with Pollux – rises at sunset.
As the sky darkens further, Mars is nearly two-thirds of the way up in the sky above the southeast horizon. In continues to eastward march through Pisces as it approaches the Pisces – Aries border and a conjunction next month with Uranus.
Use a binocular to spot the starry background with Mars. The Red Planet is 1.0° to the lower right of Pi Piscium (π Psc on the chart) and 2.7° to the upper right of Omicron Piscium (ο Psc).
Two hours after sunset. the bright moon is low in the east-northeastern sky.
Read about Mars during December.
Detailed note: Castor rises at sunset. One hour after sunset, Jupiter – nearly 8° up in the southwest – is 1.0° to the upper left of Saturn. Jupiter is 1.0° to the lower left of σ Cap. Farther east, Mars is nearly 55° up in the southeast. Its eastward march, places it 1.0° to the lower right of π Psc and 2.7° to the upper right of ο Psc. Two hours after sunset, the moon (16.3d, 99%) is about 13° up in the east-northeast. It is 5.2° to the right of Pollux (β Gem, m = 1.2).
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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