December 18, 2025: The sun nears its solstice point as daylight shortens. See the waning crescent moon, Mercury sinking into morning twilight, and bright Jupiter and Saturn.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:13 a.m. CST; Sunset, 4:22 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 appears near its southernmost point along the horizon as the shortest daylight period approaches for the northern hemisphere. At Chicago’s latitude, daylight lasts 9 hours, 8 minutes. From Miami, sunshine spans 10 hours, 32 minutes, while from Anchorage the daylight interval is only 5 hours, 28 minutes. At noon the sun stands overhead at the Tropic of Capricorn.
Moon: The lunar orb is nearing the end of lunation 1273 – the count of lunar cycles that began over a century ago. This morning, moonrise occurs less than an hour before sunrise. The next lunation begins with New Moon tomorrow at 7:43 p.m. Central Time. The waxing crescent returns to the western sky on the 22nd.
Inner Planets
Mercury: The innermost planet recedes into brighter morning twilight while brightening as it heads toward superior conjunction behind the sun on January 21st. This morning, Mercury rises less than 90 minutes before sunrise. Forty-five minutes later, it is 6° above the southeast horizon and 5.2° to Graffias’ lower left, part of Scorpius. The pair fits tightly into the same binocular field. Find a clear horizon toward Mercury’s direction, preferably across open water or farm fields, or view from a hilltop or elevated structure. See Mercury before it disappears into brighter light.
Venus: After its pretty display for most of the year, the Morning Star moves toward superior conjunction on January 6th. Afterward, it becomes the Evening Star, reappearing low in the western sky with Mercury during late February.
Bright Outer Planets
Mars: The Red Planet is still east of the sun, setting only 20 minutes after sundown. It reaches solar conjunction on January 9th. Mars first becomes visible before sunrise during late spring.
Jupiter: The Jovian Giant approaches opposition on January 10th, when Earth is between the sun and the planet. In the sky nearly all night and brighter than any star, Jupiter rises in the east-northeast less than two hours after sunset. It is high in the south after midnight. During morning twilight, it is about 30° up in the western sky. Jupiter retrogrades in front of Gemini, 6.7° from Pollux. Watch it open a gap, passing Castor in a wide conjunction on January 5th.
Saturn: The Ringed Wonder continues in a prime location for telescopic inspection after sunset. As darkness falls, Saturn is about halfway from the southern horizon to overhead. It remains in the southern sky for several hours, appearing farther westward, and sets around midnight. Through a telescope, the rings appear nearly edge-on – a view that occurs every 15 years – and because they reflect light away from Earth, several of Saturn’s larger moons can be visible depending on the telescope.
Distant Outer Planets
Uranus: Until the moon brightens the evening sky, the Tilted World is easy to locate in the same binocular field as the Pleiades star cluster, the miniature dipper high in the southeastern sky. Aquamarine Uranus is about the same brightness as 13 and 14 Tauri.
Neptune: The solar system’s most distant planet remains a challenge through a telescope. Over three times farther away than Saturn, Neptune is visible with averted vision, appearing as a faint bluish star in the upper-left portion of the field when the center is held in focus. Attempt to see it each clear evening until moonlight interferes.
Catch Mercury before it disappears into brighter twilight, while Jupiter and Saturn remain easily visible during nighttime hours.
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