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This is the Griffith Observatory Sky Report for the period between December 1 and December 31, 2023. Here are the events happening in the sky of southern California.

Mercury, on the 1^st, sets in the southwest at 6:00 p.m., PST, and the sun sets at 4:44 p.m., PST, one hour 16 minutes later. On the 22^nd, the planet is too close to the sun and is unobservable. On the 31^st, Mercury rises in the southeast at 5:37 a.m., PST, and the sun rises 6:59 a.m., PST, one hour 22 minutes later. Do not observe any planet when it comes close to the sun, for the danger to the eyes is great.

Venus rises in the southeast at 3:13 a.m., PST, on the 1^st, and the sun rises at 6:41 a.m., PST. The planet is 68-percent illuminated and 17 arcseconds wide. On the 31^st, Venus rises at 4:06 a.m., PST, and is 78-percent illuminated and 14 arcseconds wide.  Venus remains in the morning sky until February.

Mars moves behind the sun and so is unobservable. Later, when the planet is visible again, the disk of Mars will remain small until a few months before January, 2025, the time of the planet’s next opposition.

Jupiter is in Aries the Ram. On the 1^st, Jupiter sets in the west at 4:11 a.m., PST, and is 48 arcseconds wide. On the 31^st, Jupiter sets at 2:07 a.m., PST, and the planet is 44 arcseconds wide. A magnification of 50x will show the Red Spot, and the four bright Galilean moons may be seen moving back and forth, roughly in a line centered on Jupiter.

Saturn is in Aquarius the Water Bearer. On the 1^st, the planet sets in the west-southwest at 10:53 p.m., PST, and is 17 arcseconds wide. On the 31^st, Saturn sets at 9:05 p.m., PST. A magnification of 50x is needed to see the rings and Saturn’s largest moon Titan.

Uranus is in Aries the Ram. On the 1^st, Uranus sets in the west-northwest at 5:17 a.m., PST, and at 3:15 a.m., PST, on the 31^st.  On the 15^th, Uranus is at Right Ascension 3^h 9^m 59^s and declination +17° 24ʹ 3ʺ. The planet continues its retrograde motion as it moves east to west among the stars. A magnification of 200x is needed to see its 3.8-arcsecond-wide disk.

Neptune is in Pisces the Fishes. On the 1^st, the planet sets in the west-southwest at 12:51 a.m., PST. On the 31^st, Neptune sets at 10:50 p.m., PST. On the 15^th, Neptune is at Right Ascension 23^h 43^m 17^s and declination -3° 10ʹ 3ʺ.  Neptune ends its retrograde motion on the 6^th. A magnification of 200x is needed to see its 2.4-arcsecond-wide disk.

Last quarter occurs on the 4^th, new moon on the 12^th, first quarter on the 19^th, and full moon on the 26^th.

SPECIAL EVENTS

The winter solstice occurs on December 21 at 7:27 p.m., PST. The sun reaches its southernmost point on the ecliptic, reverses its movement south, and heads north.  This marks the longest night and the shortest day of the year. The sun rises at 6:55 a.m., PST, and sets at 4:48 p.m., PST.  The day is 9 hours 53 minutes long.

The Geminid meteor shower is usually the strongest meteor shower of the year. The shower is active from November 19 through December 24, and peaks from the evening of the 13^th through the morning of the 14^th. The Geminids are often bright and intensely colored. On the night of the 13^th, the moon will be a one-percent waxing crescent. The Geminids can reach rates of 150 meteors per hour when Gemini is highest.

The Ursid meteor shower appears from the 13^th through the 24^th, with the peak occurring from the night of the 21^st to the morning of the 22^nd. Observers will normally see 5-10 Ursids per hour during the late morning hours on the date of maximum activity. There have been occasional outbursts when rates have exceeded 25 per hour. The parent object is the comet 8P/Tuttle. The moon will be a 74-percent waxing gibbous.

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