December 21, 2025: Sun reaches its solstice point, a thin lunar crescent returns, and Jupiter and Saturn shine during the long nights. Mercury retreats into bright twilight.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:15 a.m. CST; Sunset, 4:23 p.m. CST. Times are calculated by the US Naval Observatory’s MICA computer program. Check local sources for sunrise and sunset times.
Solar System Almanac for Sun, Moon, and Planets
Sun: The central star reaches celestial longitude 270° at 3:03 p.m. Central Time, marking the beginning of astronomical winter in the northern hemisphere. The season’s duration is 88 days, 23 hours, and 43 minutes, with its mid-point on February 3rd at 8:55 p.m.
At Chicago’s latitude, daylight spans 9 hours, 8 minutes. In Miami, the sun shines for 10 hours, 32 minutes, while Anchorage experiences only 5 hours, 27 minutes. In comparison, on this first day of astronomical summer at Sydney, Australia’s latitude, the sun is in the sky for 14 hours, 25 minutes.
Moon: The lunar orb is 1.9 days into the new lunation, with an illumination of 3%. It sets 80 minutes after sunset. Sky watchers with an unobstructed southwestern horizon and some diligence can find the thin crescent through a binocular, over 5° above the southwest horizon at 30 minutes after sundown. Tomorrow evening, the waxing crescent is easier to see after nightfall.
Inner Planets
Mercury: The innermost planet retreats into brighter morning twilight after its best morning appearance of the year. With a clear southeastern horizon, find Mercury less than 5° above the horizon at 45 minutes before sunrise. It reaches superior conjunction on the sun’s far side on January 21st.
Venus: Like Mercury, the Morning Star is veiled by bright morning twilight, rising only 15 minutes before sunrise. It reaches superior conjunction on January 6th. By late February, Venus appears low in the western sky with Mercury and Saturn.
Bright Outer Planets
Mars: The Red Planet is immersed in bright evening twilight, setting only 16 minutes after the sun. It reaches solar conjunction on January 9th and does not emerge from morning twilight until late spring.
Jupiter: With Venus out of view, the Jovian Giant outshines all other stars in the sky. Nearing its opposition with the sun, when Earth is between the planet and the sun, Jupiter is in the sky nearly all night. It rises in the east-northeast less than two hours after sundown. It is high in the south after midnight and about 30° up in the west during morning twilight. Through a telescope, the planet’s four large moons are easily visible, along with cloud bands that stretch parallel to the equator. Depending on the time, the Great Red Spot might be visible.
Jupiter gently retrogrades in front of Gemini, 6.5° from Pollux, one of the Twins. It passes Castor, the other Twin, on January 5th. Retrograde is the illusion when a planet moves westward compared to the distant star field. This occurs as Earth overtakes an outer planet near the time of opposition.
Saturn: The Ringed Wonder is in a prime location for telescopic examination after darkness falls, nearly halfway from the southern horizon to overhead. The rings are seen nearly edge-on — a view that occurs every 15 years. Depending on the telescope’s properties, several of its moons may be visible. Saturn sets before midnight.
Faint Outer Planets
Uranus: The Tilted World is in the same binocular field with the Pleiades star cluster, which resembles a miniature dipper. Aquamarine Uranus is near the stars 13 and 14 Tauri (Tau). Look for Taurus and the Pleiades in the eastern sky during the early evening.
Neptune: The solar system’s most-distant planet is in the same binocular field as Saturn, although it is over three times farther away. They are in the southern sky after evening twilight ends. Through a binocular, use averted (peripheral) vision to identify bluish Neptune appearing as a dim star.
As the new season begins, look for Jupiter and Saturn during the nighttime hours. Use a binocular to find Uranus and Neptune.
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