2025, December 4: Earliest Sunsets, Mercury’s Best Morning Showing, and the Full Cold Moon

December 4, 2025: Mercury reaches its best morning visibility of the year while the Full Cold Moon shines near Aldebaran and Saturn remains well-placed after sunset. Jupiter dominates the night as Venus descends into brighter morning light.

2018, December 9: Mercury joins brilliant Venus during morning twilight.
Photo Caption – 2018, December 9: Mercury joins brilliant Venus during morning twilight.

by Jeffrey L. Hunt

Chicago, Illinois: Sunrise, 7:02 a.m. CST; Sunset, 4:20 p.m. CST.  Times are calculated by the US Naval Observatory’s MICA computer program. Check local sources for sunrise and sunset times.

Earliest Sunset

The earliest sunset occurs today and continues through the 14th.

Before Sunrise

Mercury, December 4, 2025
Chart Caption – 2025, December 4: During morning twilight, Mercury is low in the east-southeast.

Before sunrise, Mercury nears its largest separation from the sun, known as greatest elongation, in a few mornings. The planet seems to hug the sun, appearing low in the sky during morning twilight.

This morning, at 45 minutes before sunrise, the speedy planet is low in the east-southeast, below Zubenelgenubi and Zubeneschamali, the Scorpion’s claws. Mercury is bright, although muted by the colors of mid-twilight and the filtering effects of Earth’s atmosphere. Use a binocular for its initial identification.

Farther westward, the bright moon is low in the west-northwest after last evening’s occultation of the Pleiades.

Jupiter

Jupiter before sunrise, December 4, 2025
Chart Caption – 2025, December 4: At 45 minutes before sunrise, Jupiter is less than halfway up in the western sky near Pollux and Castor, the Gemini Twins.

At this hour, Jupiter is higher in the sky, less than halfway from the western horizon to overhead. It is to the lower left of Pollux, a Gemini Twin.

Jupiter is the brightest starlike body in the sky as Venus disappears into brighter morning light. Only the moon is brighter overnight.

Venus

Venus is about a month from superior conjunction on the sun’s far side. This morning it rises 40 minutes before the sun. Under ideal conditions — a view toward a natural horizon free of obstructions — it is visible a few degrees above the east-southeast horizon 20 minutes later. A hilltop or elevated structure is helpful. Use a binocular to locate it, then look without the optical assist.

After Sunset

Saturn, December 4, 2025
Chart Caption – 2025, December 4: After sunset, Saturn is in the south-southeast.

After sundown, Saturn is less than halfway from the south-southeast horizon to overhead. It gently moves eastward against Pisces, although its faint stars are washed out by tonight’s bright moonlight. The Ringed Wonder is in a prime position for telescopic examination during the early evening. Ask your neighborhood sky watchers to show you Saturn through their telescopes.

Evening Moon

Moon, December 4, 2025
Chart Caption – 2025, December 4: Jupiter is low in the east-southeast near Pollux at five hours after sunset.

Farther eastward, the Full (Cold) moon — occurring at 5:14 p.m. Central Time — is low in the east-northeast, 10.4° to Aldebaran’s upper left, Taurus’ brightest star.

During the night, the planets, moon, and stars appear farther westward. Jupiter rises about three hours after sunset. Two hours later, the moon is over halfway up in the east-southeast. Look for the Bull’s horns, Elnath and Zeta Tauri, to the lunar orb’s lower left. A binocular might be needed to see them.

Jupiter

Jupiter, December 4, 2025
Chart Caption – 2025, December 4: Jupiter is low in the east-southeast near Pollux at five hours after sunset.

Bright Jupiter is low in the east, about 20° above the horizon and to the moon’s lower left. The Jovian Giant slowly retrogrades in front of Gemini, 6.5° to Pollux’s lower right.

By tomorrow’s morning twilight, the moon is low in the west-northwest while Jupiter is higher in the western sky. From the moon’s eastward motion, the lunar orb is below Elnath during morning twilight.

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