December 20, 2025: Mercury disappears into brighter morning twilight as daylight reaches its minimum. See the planet low in the southeast before sunrise along with nearby Scorpius stars.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:14 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.
At Chicago’s latitude, daylight is at its shortest interval, 9 hours, 8 minutes. This continues through December 23rd.
Mercury Retreats into Morning Twilight
During this period of minimum daylight, Mercury disappears into brighter morning twilight — a circumstance that does not occur every year. After greatest elongation on December 7th — the point when the planet appears farthest from the sun for this apparition — the speedy planet rises this morning 82 minutes before sunrise. Nearly 40 minutes later, Mercury is over 5° above the southeast horizon.
Find an unobstructed horizon looking in Mercury’s direction. It is bright, although its visibility is muted by the colors of morning twilight and the filtering effects of the atmosphere near the horizon that dims and blurs celestial bodies. A binocular helps with the initial identification.
Mercury is in front of Ophiuchus as it passes the Scorpion, making its first morning appearance of the year. Through the binocular, find Graffias and Dschubba at the Scorpion’s head, over 8° to Mercury’s upper right and outside the field of view that contains Mercury. Find Mercury, then move the binocular slightly to the upper right to see the stars.
Antares, the Scorpion’s heart in celestial artwork, is nearing its first morning appearance or heliacal rising. It becomes visible in several mornings. Because of its reddish color, the reddish hues near the horizon mute it more than bluer stars. With that ideal horizon, this star is 5.5° to Mercury’s lower right.
Mercury aficionados can chase the planet into brighter twilight. For us today, we say, “Goodbye, Mercury.”
Venus and Mercury, February 2026
Mercury reaches superior conjunction on the sun’s far side on January 21st. During late February, Venus and Mercury are near each other during evening twilight.
Take a last look for Mercury for this morning appearance, the best of 2025.
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