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This is the Griffith Observatory Sky Report for the period between December 1 and December 31, 2024. Here are the events happening in the sky of southern California.
Mercury begins December too close to the sun for safe observation. On the 11th, Mercury rises in the east-southeast at 5:48 a.m., PST, and the sun rises at 6:49 a.m., PST, one hour one minute later. The planet is 10-percent illuminated and 9.4 arcseconds wide. On the 31st, Mercury rises at 5:25 a.m., PST, and the sun rises at 6:59 a.m., PST, one hour 34 minutes later. Mercury is 76 -percent illuminated and 6.0 arcseconds wide. Do not observe any planet when it comes close to the sun, for the danger to the eyes is great.
Venus sets in the west-southwest at 7:47 p.m., PST, on the 1st, and is 67-percent illuminated and 17 arcseconds wide. On the 31st, Venus sets at 8:37 p.m., PST. Venus is 56-percent illuminated and 22 arcseconds wide. A small telescope will show the disk with a magnification of 100x.
Mars is in Cancer the Crab. On the 1st, the planet rises in the east-northeast at 8:40 p.m., PST, and is 93-percent illuminated and 12 arcseconds wide. On the 31st, Mars rises at 6:18 p.m., PST, and is 99-percent illuminated and 14 arcseconds wide. From the 1st through the 7th, Mars is within two degrees of the large bright open cluster Messier 44. On the 17th, Mars is less than one degree south of the moon. Mars reaches opposition on January 16, 2025.
Jupiter is in Taurus the Bull. On the 1st, the planet rises in the east-northeast at 5:05 p.m., PST, and is 48 arcseconds wide. On the 31st, Jupiter rises at 2:52 p.m., PST, and is 47 arcseconds wide. A telescope capable of magnification 50x will show the Red Spot, and the four bright Galilean moons can be seen moving back and forth, across and behind Jupiter.
Saturn is in Aquarius the Water Bearer. On the 1st, Saturn sets in the west at 11:46 p.m., PST, and is 17 arcseconds wide. On the 31st, Saturn sets at 9:56 p.m., PST. The rings and Saturn’s largest moon, Titan, can be seen with a telescope capable of magnification 50x.
Uranus is in Taurus the Bull. On the 1st, the planet sets in the west-northwest at 5:35 a.m., PST. On the 31st, Uranus sets at 3:32 a.m., PST. On the 15th, Uranus is at Right Ascension 3h 27m 21s and declination +18° 33ʹ 26ʺ. A magnification of 150x or more is needed to see the planet’s 3.8-arcsecond disk.
Neptune is in Pisces the Fishes. On the 1st, Neptune sets in the west at 12:59 a.m., PST. On the 31st, Neptune sets at 10:58 p.m., PST. On the 15th, Neptune is at Right Ascension 23h 51m 35s and declination -2° 19ʹ 27ʺ. A magnification of 150x or more is needed to see the planet’s 2.3-arcsecond disk.
The moon is at first quarter on the 8th. Full moon is on the 15th, last quarter on the 22nd, and new moon is on the 30th.
SPECIAL EVENTS
In the major lunar standstill of 2024-2025, December’s northern extreme excursion of the moon occurs on Sunday, December 15, when the moon is full. On December 15, moonrise occurs in Los Angeles at 5:03 p.m., PST, and the moon sets on Monday morning, December 16, at 8:28 a.m., PST. The moon’s northernmost moonrise will be observed in a public event on December 15 on the grounds at Griffith Observatory, where the moon will rise over the San Gabriel Mountains just east of Occidental Peak at 5:23 p.m., PST. Griffith Observatory’s Livestream Broadcast Team will transmit the moonrise to the Internet with a program that begins at 5:03 p.m., PST. Details are available at Griffith Observatory.org. The southern extreme excursion of the moon takes place on December 30-31, but that moon is new and not visible.
The winter solstice occurs on December 21 at 1:20 a.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.
Lunar-X is visible on the 7th for a few hours, from 6:36 p.m., PST. Lunar-X is a feature on the first quarter moon just within the dark half of the moon and midway between the center point and the southern edge. It is due to the rims of two craters illuminated by the sun. A telescope with a magnification of 50x or more is needed to see it.
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 13th through the morning of the 14th. This is the one major shower that provides good activity prior to midnight, as the constellation of Gemini is well placed from 10:00 p.m., PST, onward. The Geminids are often bright and intensely colored. Due to their medium-slow velocity, persistent trains are not usually seen. The parent object is the asteroid 3200 Phaethon and not a comet, as is usual for meteor showers. On the night of the 13th, the moon will be 97-percent full and will interfere with observations.
The Ursid meteor shower is often neglected, for it peaks just before Christmas with a rate much lower than the Geminids, which peak a week before the Ursids. This year the Ursids appear from the 13th through the 24th, with the peak occurring from the night of the 21st to the morning of the 22nd. Observers normally see 5-10 Ursids per hour during the late morning hours on the date of maximum activity. There have been occasional outbursts with rates exceeding 25 per hour. The parent object is the comet 8P/Tuttle. The moon will be a 59-percent waxing gibbous and will interfere with observations until after midnight.
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