December 20, 2022: The waning lunar crescent is to the lower left of Zubenelgenubi before sunrise. After sunset, look for the five bright planets from the southwest to the east-northeast.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:14 a.m. CST; Sunset, 4:22 p.m. CST. Check local sources for sunrise and sunset times for your location.
Daylight has reached the shortest time interval for the year, nine hours, eight minutes. Latest sunrise time (7:18 a.m. CST) begins on the 28th and lasts through January 10th.
Jupiter’s Great Red Spot’s transit times, when it is in the center of the planet in the southern hemisphere: 0:20 UT, 10:16 UT, 20:11 UT. Convert the time to your time zone. In the US, subtract five hours for EST, six hours for CST, and so on. Use a telescope to see the spot. Times are from Sky & Telescope magazine.
Summaries of Current Sky Events
Here is today’s planet forecast:
Morning Sky
No bright planet is in the sky this morning before sunrise. At one hour before sunup, the crescent moon, 11% illuminated, is less than 20° up in the southeast, 4.3° to the lower left of Zubenelgenubi – meaning “the southern claw of the scorpion.”
The moon is showing earthshine again this morning, an effect from sunlight reflected from Earth that gently illuminates the lunar night. From the moon, Earth is nearly at its full phase, shining brightly.
Zubenelgenubi and the northern claw, Zubeneschamali, are part of today’s Libra. Older maps show one constellation with the creature’s long pincers now reaching across the southeast horizon. The forehead, Dschubba, is nearly 10° up in the southeast.
Tomorrow morning the crescent is above Antares, meaning “the rival of Mars,” that is making its first morning or heliacal rising after its solar conjunction earlier this month. Try to look for the reddish star with a binocular above the horizon. During the next day or two it is visible to the unaided eye.
Evening Sky
Look for the five-planet display after sundown. In order of brightness the planets are: Venus, Jupiter, Mars, Mercury, and Saturn. During brighter twilight, the challenging view is Saturn. Jupiter and Mars are farther eastward and away from the brighter sky in the west.
Find a location with a clear view of the entire sky from the southwest to the south and back to the east-northeast, but especially toward where the sun sets.
At thirty-five minutes after sunset, brilliant Venus is less the 5° above the southwest horizon. It is about one binocular field to the right of the southwest point. The planet is bright enough to be seen without that optical assist.
Mercury is 5.6° to the upper left of Venus. Both are in the same binocular field. Place Venus toward the lower right portion of the field of view. Mercury is then to the upper left. Can you see Mercury without the binocular?
Saturn, about one-third of the way up in the south-southwest, is over 30° to the upper left of Mercury. Can you see Saturn? It may be necessary to look for it with the binocular before you can see it without the optical help.
Jupiter is over halfway up in the south-southeast and Mars is in the east-northeast.
As the sky darkens further, Saturn may come into view before Venus sets.
By 45 minutes after sundown, Venus is a few degrees above the horizon, theoretically visible, but likely blocked by distant terrestrial features, or atmospheric effects. Mercury is to the upper left.
Tomorrow (9:31 a.m. CST), when Mercury is the sky during the daytime to the east of the sun, it reaches its greatest angular separation from the sun. It still gains another two minutes of setting time, but its brightness begins to fade during the next week.
The crescent moon enters the southwestern sky on the 24th. By then Venus gains another six minutes of setting time, allowing the sky to darken further before it sets. On the 26th, the moon is near Saturn, making its identification easier.
This evening Jupiter is in the south-southeast at 45 minutes after sundown and it is easily identified. Saturn is also visible.
Mars is about 20° above the east-northeast horizon. Aldebaran is to the planet’s lower right and Capella is to the upper left. Mars is brighter than the stars.
As the evening progresses, Mercury and Venus disappear below the western horizon, as Saturn, Jupiter, and Saturn seem to move farther westward, marking the ecliptic, the plane of the solar system.
Tomorrow morning the crescent moon is near Antares, marking its heliacal rising.
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