December 21, 2023: Winter begins in the northern hemisphere. Jupiter and Saturn are visible in the evening sky three years after their Great Conjunction.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 7:15 a.m. CST; Sunset, 4:23 p.m. CST. Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.
Winter Solstice
The sun’s apparent motion in the sky is from Earth’s daily rotation, tilt, and annual revolution around the sun. The central star reaches its most southerly distance from the celestial equator – a circle in the sky above Earth’s equator – at 9:27 p.m. CST. This event signals the start of astronomical winter in the northern hemisphere and summer south of the equator. The season lasts eighty-eight days, twenty-three hours, and thirty-nine minutes until the sun appears to cross the celestial equator on March 19, 2024 at 10:06 p.m. CDT. The season’s midpoint occurs February 4th at 9:16 a.m. CST.
Great Conjunction
Three years ago, Jupiter passed Saturn in a close conjunction. Nearly every twenty years, Jupiter overtakes and passes the Ringed Wonder, known as a great conjunction. The next conjunction of the largest outer planets occurs November 5, 2040.
Since the Great Conjunction in 2020, Jupiter has moved eastward faster than Saturn. The Jovian Giant has moved nearly 85° eastward against the starfield, while the Ringed Wonder is nearly 22° east of the conjunction point, with a gap between them of over 63°.
The gap between the planets continues to widen until November 19, 2030, when the two planets are at opposition and 180° apart in the sky. When one rises the other sets. After the planet-to-planet opposition, Jupiter begins to overtake Saturn, closing the gap until the 2040 Great Conjunction.
Summaries of Current Sky Events
Summary for Venus as a Morning Star, 2023-24
Here is today’s planet forecast:
Morning Sky
Venus
An hour before sunrise, brilliant Venus stands over 20° above the southeast horizon. This morning, the Morning Star passes 6.3° to the lower right of Zubeneschamali, the Scorpion’s northern claw. The planet is 4.9° to the lower left of Zubenelgenubi, the southern claw.
Venus is stepping toward the Scorpion’s head, Dschubba, less than 14° to the planet’s lower left and nearly 10° above the horizon. The planet passes 0.9° to the upper left of Graffias on New Year’s Day.
Antares, representing the Scorpion’s heart, is nearing its heliacal rising, or first morning appearance. These events have theoretical dates, but they are affected by local weather and sky clarity on the day of the predicted first appearance. The actual appearance could be early depending on the weather or late for the same reason. Use a binocular to find it about 4° above the horizon at forty-five minutes before the sun rises.
Mars continues its slow climb into the morning sky. It is not, yet, visible, rising forty-one minutes before the sun.
Evening Sky
Bright Jupiter, Saturn
Mercury races toward inferior conjunction, between Earth and Sun, tomorrow. Then it moves into the morning sky appearing about 11° to the lower left of Venus during mid-January.
An hour after sundown, Jupiter and Saturn span over 60°. The bright moon, 74% illuminated, is over halfway up in the southeast and 7.6° to the upper right of bright Jupiter.
The bright moonlight washes out the dimmer stars in the sky and illuminates the ground. Shadows on the ground are easy to see from the bright light.
The star Hamal, Aries’ brightest star, is 11.4° to the upper left of Jupiter.
Saturn, distinctly dimmer than Jupiter, but brighter than most stars in the sky tonight, is over 30° above the south-southwest horizon. The planet is slowly moving eastward in front of Aquarius, but the stars are awash in moonlight.
The star Fomalhaut, slightly dimmer than Saturn, is over 20° to the lower left of the planet.
During the night the sky seems to shift westward, Saturn sets in the west-southwest, nearly five hours after sundown and long before midnight. Jupiter and the moon are south about an hour before Saturn sets. As Jupiter and the moon approach the western horizon at six hours before sunrise tomorrow morning, the gap between them is 4.4°.
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