Daily Guide

A detailed guide to the night sky written by a NASA expert featuring full Moon lore, asteroid flybys, stars, galaxies, constellations, and more.

Full moon rising over a forest.

December 2023

By Gordon Johnston

The next full Moon will be on Monday morning, November 27, 2023, appearing opposite the Sun (in Earth-based longitude) at 4:16 AM EST. This will be on Sunday evening from Marquesas Islands time westward to the International Date Line in the mid-Pacific. The Pleiades star cluster will appear 4 degrees to the lower right of the Moon (but may be masked by the brightness of the Moon). The Moon will appear full for about 3 days centered on this time, from Saturday night to Tuesday morning.

The phases of the Moon for December 2023.
NASA/JPL-Caltech

The Maine Farmers' Almanac began publishing "Indian" names for full Moons in the 1930s. Over time these names have become widely known and used. According to this almanac, as the full Moon in November this is the Beaver Moon, the Frost or Frosty Moon, or the Snow Moon. For the Beaver Moon, one interpretation is that mid-Fall was the time to set beaver traps before the swamps freeze to ensure a supply of warm winter furs. Another interpretation is that the name came from how active the beavers are in this season as they prepare for winter. The Frost, Frosty, or Snow Moon names come from the frosts and early snows that begin this time of year, particularly in northeastern North America.

As the full Moon before the winter solstice, an old European names for this Moon include the Moon before Yule and the Oak Moon. Yule was a 3-day winter solstice festival in pre-Christian Europe. In the tenth century King Haakon I associated Yule with Christmas as part of the Christianization of Norway, and this association spread throughout Europe. Some believe that the Oak Moon name ties back to ancient druid traditions of harvesting mistletoe from oak trees, a practice first recorded by the Roman historian Pliny the Elder in the first century CE. The term "druid" may derive from the Proto-Indo-European roots for "oak" and "to see," suggesting "druid" means "oak knower" or "oak seer."

Throughout Southeast Asia numerous related festivals are celebrated around this full Moon. This is Kartik Purnima (the full Moon of the Hindu lunar month of Kartik) and is celebrated by Hindus, Jains, and Sikhs (each for different reasons). Karthika Deepam is a festival observed by Hindus of Tamil Nadu, Sri Lanka, and Kerala when the nearly full Moon lines up with the Pleiades constellation (Krittika or Karttikai). This year it will be on Sunday, November 26, 2023. Some areas celebrate multi-day festivals that include this full Moon. In Thailand and nearby countries this full Moon is Loy Krathong, a festival that includes decorating baskets and floating them on a river. In Cambodia this full Moon corresponds with the 3-day Bon Om Touk ("Boat Racing Festival") or the Cambodian Water Festival featuring dragon boat races. In Myanmar this is the Tazaungdaing Festival, a festival that predates the introduction of Buddhism and includes the launching of hot air balloons (sometimes flaming or laden with fireworks). In Sri Lanka this is Ill (or Il) Poya, commemorating the Buddha's ordination of sixty disciples as the first Buddhist missionaries.

This is the Child Moon. Four years ago, then 7 year old Astrid Hattenbach was walking home from school with her father Henry Throop (a friend and former coworker at NASA Headquarters). When she saw the rising full Moon, she said: "You know what this Moon is called? It's called a Child Moon. Because the Moon rises at a time that the children, they can see it, because they're not in bed, and they might even be outside like we are right now." Henry told me about this and I thought it a perfect name. This year (at least for Washington, DC and similar latitudes), the earliest evenings with a full Moon in the sky will be on November 25 through 27, 2023, with sunset at 4:48 PM and evening twilight ending at 5:50 PM EST. November 28 could also be included, except that the Moon will rise just a few minutes before evening twilight ends and will be low on the horizon when the sky first darkens.

In many lunar and lunisolar calendars the months change with the new Moon and full Moons fall in the middle of the lunar month. This full Moon is the middle of the tenth month of the Chinese year of the Rabbit, Kislev in the Hebrew calendar, and Jumādā al-ʾŪlā, the fifth month of the Islamic calendar. Hanukkah begins towards the end of Kislev, and this year starting with sundown on Thursday, December 7, 2023, and ending early in the next month, Tevet, with sundown on Friday, December 15.

As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Make sure you are ready for winter and take advantage of these early sunsets to enjoy and share the wonders of the night sky. 

As for other celestial events between now and the full Moon after next (with times and angles based on the location of NASA Headquarters in Washington, DC):

As autumn ends and winter begins, the daily periods of sunlight reach their shortest at the winter solstice and then begin to lengthen again. On Monday, November 27, 2023 (the day of the full Moon), morning twilight will begin at 6:01 AM, sunrise will be at 7:03 AM, solar noon will be at 11:56 AM when the Sun will reach its maximum altitude of 30.0 degrees, sunset will be at 4:48 PM, and evening twilight will end at 5:50 PM.

Our 24-hour clock is based on the average length of the solar day. Although the day of the winter solstice is sometimes called the "shortest day of the year" (because it has the shortest period of sunlight), the solar days near the solstice are actually the longest days of the year. Because of this, the earliest sunset of the year occurs before the solstice and the latest sunrise of the year (ignoring Daylight Savings Time) occurs after the solstice. For the Washington, DC area, the earliest sunset of the year will occur on Thursday, December 7, 2023. On this day, morning twilight will begin at 6:10 AM EST, sunrise will be at 7:13 AM, solar noon will be at 11:59 AM when the Sun will reach its maximum altitude of 28.5 degrees, sunset will be at 4:45:50 PM, and evening twilight will end at 5:49 PM.

Thursday, December 21, 2023, will be the day of the Northern Hemisphere winter solstice, the astronomical end of fall and start of winter. The winter solstice is the day when the Sun at solar noon is lowest in the sky and the time from sunrise to sunset is shortest for the year. For the location of NASA Headquarters, the time from sunrise to sunset will be 9 hours, 26 minutes, 13 seconds. Solar noon will be at 12:06 PM when the Sun will reach its lowest daily high of the year, 27.7 degrees. The longest solar day of the year (measured from noon to noon on a sundial) will be from solar noon on December 21 to solar noon on December 22, 29.8 seconds longer than 24 hours.

By Tuesday, December 26 (the day of the full Moon after next), morning twilight will begin at 6:22 AM, sunrise will be at 7:25 AM, solar noon will be at 12:09 PM when the Sun will reach its maximum altitude of 27.8 degrees, sunset will be at 4:52 PM, and evening twilight will end at 5:56 PM.

Meteor Showers

One of the major meteor showers of the year, the Geminids (004 GEM), will be active from December 4 to 17, with a broad peak overnight from December 13 to 14, 2023. Under ideal conditions this meteor shower is predicted to peak at about 150 visible meteors per hour. This meteor stream gets its name because the meteors appear to radiate out from near the constellation Gemini.

For the Washington, DC area and similar latitudes, the time to start looking will likely be after 8:30 PM EST the evening of Wednesday, December 13, 2023 (about 2 hours after the radiant rises above the northeastern horizon). The radiant will reach its highest in the sky around 2 to 3 AM. After about 6 AM Thursday morning, December 14, the first hints of dawn will begin to interfere.

Ideal conditions would be when the weather cooperates by being clear with no clouds or hazes, the radiant is high in the sky, you go to a place far from any light sources or urban light pollution, and you have a clear view of a wide expanse of the sky. Be sure to give your eyes plenty of time to adapt to the dark. The rod cells in your eyes are more sensitive to low light levels but play little role in color vision. Your color-sensing cone cells are concentrated near the center of your view with more of the rod cells on the edge of your view. Since some meteors are faint, you will tend to see more meteors from the "corner of your eye" (which is why you need to view a large part of the sky). Your color vision (cone cells) will adapt to darkness in about 10 minutes, but your more sensitive night vision rod cells will continue to improve for an hour or more (with most of the improvement in the first 35 to 45 minutes). The more sensitive your eyes are, the more chance you will have of seeing meteors. Even a short exposure to light (from passing car headlights, etc.) will start the adaptation over again (so no turning on a light or your cell phone to check what time it is).

These meteors are caused by debris that enters the Earth's atmosphere at 35 kilometers per second (78,000 miles per hour). The Geminids appear to be one of the few annual meteor showers associated with asteroids rather than comets. The debris that causes the Geminids appears to come from the asteroid 3200 Phaethon, which has an eccentric 1.4 year orbit that takes it out as far as the main asteroid belt and much closer to the Sun than Mercury. The problem is that it is hard to explain why we see so many meteors since we don't see evidence of enough material coming off this asteroid now, suggesting it was more active in the past.

Several other meteor showers are expected to peak during this lunar cycle, including a possible new shower caused by debris from the comet 46P/Wirtanen, but these are expected to be much harder to see, as they either have a low peak rate, are best seen from the Southern Hemisphere, and/or peak when moonlight will interfere for most of the night.

Evening Sky Highlights

The next few months should be a great time for Jupiter and Saturn watching, especially with a backyard telescope. Saturn was at its closest and brightest for the year on August 27, 2023, and Jupiter was at its closest and brightest on November 2, (called "opposition" as this is when they are opposite from the Sun as seen from Earth). Both will appear to shift westward each night, gradually making them visible earlier in the evening sky (and friendlier for backyard stargazing, especially if you have young ones with earlier bedtimes). With clear skies and a telescope you should be able to see Jupiter's four bright moons, Ganymede, Callisto, Europa, and Io, noticeably shifting positions in the course of an evening. For Saturn, you should be able to see Saturn's rings as well as Saturn's largest moon, Titan.

On the evening of Sunday, November 26 (the evening of the night of the full Moon), as evening twilight ends (at 5:50 PM EST), the rising Moon will be 17 degrees above the east-northeastern horizon. Technically, three planets will be visible. The brightest will be Jupiter at 28 degrees above the eastern horizon. Next in brightness will be Mercury, but it will be only 1 minute from setting on the west-southwestern horizon. Saturn will be 38 degrees above the southern horizon. The bright star appearing closest to overhead will be Deneb at 73 degrees above the west-northwestern horizon. Deneb is the brightest star in the constellation Cygnus the swan and is one of the three bright stars of the "Summer Triangle" (along with Vega and Altair). Deneb is about 20 times more massive than our Sun but has used up its hydrogen, becoming a blue-white supergiant about 200 times the diameter of the Sun. If Deneb were where our Sun is, it would extend to about the orbit of the Earth. Deneb is about 2,600 light years from us and is the 19th brightest star in our night sky.

As this lunar cycle progresses, Jupiter, Saturn, and the background of stars will appear to shift westward each evening (as the Earth moves around the Sun). The planet Mercury will appear low on the west-southwestern horizon, shifting to the left until about December 4 (when it will reach its greatest angular separation from the Sun for this apparition), then start to shift towards the right. On December 7 Mercury will reach its highest above the southwestern horizon as evening twilight ends for this apparition (slightly more than 2 degrees). December 14 will be the last evening Mercury will be above the west-southwestern horizon as evening twilight ends. Mercury will pass between the Earth and the Sun on November 22. The waxing Moon will pass by Saturn on December 17, Jupiter on December 21 and 22., and the Pleiades star cluster on December 23.

By the evening of Tuesday, December 26 (the evening of the night of the full Moon after next), as evening twilight ends (at 5:56 PM EST), the rising Moon will be 15 degrees above the east-northeastern horizon. Two planets will be visible. The brightest will be Jupiter at 51 degrees above the southeastern horizon. Saturn will be 33 degrees above the south-southwestern horizon. The bright object appearing closest to overhead will still be the star Deneb at 52 degrees above the west-northwestern horizon, with Jupiter a close second.

Morning Sky Highlights

On the morning of Monday, November 27 (the morning of the full Moon after next), as morning twilight begins (at 6:01 AM EST), the setting full Moon will be 13 degrees above the west-northwestern horizon. The only visible planet will be bright Venus at 28 degrees above the southeastern horizon, with the bright star Spica 5 degrees to the lower right. The bright star appearing closest to overhead will be Regulus, the brightest star in the constellation Leo the lion, at 63 degrees above the southern horizon. Although we see Regulus as a single star, it is actually four stars (two pairs of stars orbiting each other). Regulus is about 79 light years from us.

As this lunar cycle progresses, the background of stars will appear to shift westward each evening, while Venus will gradually shift the other direction, passing left of Spica towards the southeastern horizon. The waning Moon will pass near Pollux on December 1, Regulus on December 4, Spica on December 8, and bright Venus on December 9. One of the major meteor showers of the year, the Geminids (004 GEM), is expected to peak in the early morning of December 14, with the radiant at its highest in the sky around 2 to 3 AM.

By the morning of Wednesday, December 27 (the morning of the night of the full Moon after next), as morning twilight begins (at 6:22 AM EST), the setting full Moon will be 18 degrees above the west-northwestern horizon. The only visible planet will be bright Venus at 19 degrees above the southeastern horizon. The bright object appearing closest to overhead will be the star Arcturus at 61 degrees above the southeastern horizon. Arcturus is the brightest star in the constellation Boötes the herdsman or plowman, is the 4th brightest star in our night sky, and is 36.7 light years from us. While it has about the same mass as our Sun, it is about 2.6 billion years older and has used up its core hydrogen, becoming a red giant 25 times the size and 170 times the brightness of our Sun.

Detailed Daily Guide

Here for your reference is a day-by-day listing of celestial events between now and the full Moon after next. The times and angles are based on the location of NASA Headquarters in Washington, DC, and some of these details may differ for your location (I use parentheses to indicate times specific to the DC area).

Monday morning, November 20, 2023, the Moon will appear half-full as it reaches its first quarter at 5:50 AM EST.

Monday evening, November 20, 2023, the planet Saturn will appear to the right of the half-full Moon. Saturn will be 5 degrees to the upper right as evening twilight ends (at 5:52 PM EST) and will shift downward relative to the Moon until Saturn sets first on the west-southwestern horizon (at 11:43 PM), when Saturn will be 7 degrees to the lower right.

Tuesday afternoon, November 21, 2023, at 4:03 PM EST, the Moon will be at perigee, its closest to the Earth for this orbit.

Friday evening into Saturday morning, November 24 to 25, 2023, the bright planet Jupiter (near its closest and brightest for the year) will appear near the waxing gibbous Moon. As evening twilight ends (at 5:51 PM EST), Jupiter will be 6 degrees to the lower left. When the Moon reaches its highest in the sky for the night (at 9:58 PM) Jupiter will be 4 degrees to the left of the Moon. Jupiter will shift closer to the Moon until Jupiter sets on the west-northwestern horizon (at 5 AM), when it will be 2.5 degrees to the left of the Moon.

Sunday evening, November 26, 2023, will be the first evening that the planet Mercury will be (barely) above the west-southwest horizon as evening twilight ends (at 5:50 PM EST).

Although difficult to see due to the brightness of the moonlight, Sunday night into Monday morning, November 26 to 27, 2023, the Pleiades star cluster will appear just a few degrees from the full Moon.

As mentioned above, the next full Moon will be Monday morning, November 27, 2023, at 4:16 AM EST. The Moon will appear full for 3 days around this time, from Saturday evening to Tuesday morning.

Wednesday morning, November 29, 2023, the bright planet Venus, shifting downwards towards the southeastern horizon each morning, will pass at its closest (4 degrees) to the left of the bright star Spica.

Thursday night into Friday morning, November 30 to December 1, 2023, the bright star Pollux (the brighter of the twin stars in the constellation Gemini the twins) will appear near the waning gibbous Moon. As the Moon rises above the south-southeastern horizon Thursday night (at 7:33 PM EST), Pollux will be 2 degrees to the right. Pollux will appear to shift clockwise around the Moon, appearing 3 degrees to the upper right by the time the Moon reaches its highest in the sky for the night (at 3:25 AM). Pollux will be 4 degrees to the lower right of the Moon as morning twilight begins (at 6:05 AM).

Sunday night into Monday morning, December 3 to 4, 2023, the bright star Regulus will appear to the right of the waning gibbous Moon. Regulus will be 3.5 degrees to the right of the Moon as the pair rises on the east-northeastern horizon (at 10:45 PM EST). By the time the Moon reaches its highest for the night (at 5:43 AM) Regulus will be 4.5 degrees to the lower right. Morning twilight will begin 25 minutes after that (at 6:08 AM).

Monday morning, December 4, 2023, will be when the planet Mercury reaches its greatest angular separation from the Sun as seen from the Earth for this apparition (called greatest elongation). Because the angle of the line between the Sun and Mercury and the horizon varies, when Mercury and the Sun appear farthest apart as seen from the Earth is not always the same as when Mercury appears highest above the southwestern horizon as evening twilight ends, which will occur three evenings later on December 7.

Monday afternoon, December 4, 2023, at about 1:40 PM EST, the Moon will be at apogee, its farthest from the Earth for this orbit.

Early Tuesday morning, December 5, 2023, the waning Moon will appear half-full as it reaches its last quarter at 12:49 AM EST.

Thursday evening, December 7, 2023, will be the day with the earliest sunset of the year, with sunset at 4:45:50 PM EST. This will also be the start of Hanukkah. Thursday evening will also be when the planet Mercury will appear at its highest above southwestern horizon (a little over 2 degrees) at the time evening twilight ends (at 5:49 PM EST).

Friday morning, December 8, 2023, the bright star Spica will appear below the waning crescent Moon. Spica will be 4 degrees to the lower right of the Moon as Spica rises above the east-southeastern horizon (at 3:01 AM EST), and the pair will shift closer together, appearing less than 3 degrees apart by the time morning twilight begins (at 6:11 AM).

Saturday morning, December 9, 2023, the bright planet Venus will appear about 4 degrees to the left of the waning crescent Moon. Venus will rise above the east-southeastern horizon (at 3:46 AM EST) shortly after moonrise, with morning twilight beginning 2.5 hours later (at 6:12 AM).

Tuesday evening, December 12, 2023, at 6:32 PM EST, will be the new Moon, when the Moon passes between the Earth and the Sun and will not be visible from the Earth. This will be on Wednesday from West Central Africa and Central European Time eastward across the rest of Africa, Eurasia, and Australia to the International Date Line in the central Pacific.

The day of or the day after the New Moon marks the start of the new month for most lunisolar calendars. Sundown on Tuesday, December 12, 2023, will mark the start of Tevet in the Hebrew calendar. The eleventh month of the Chinese year of the Rabbit starts on Wednesday, December 13.

In the Islamic calendar the months traditionally start with the first sighting of the waxing crescent Moon. Many Muslim communities now follow the Umm al-Qura Calendar of Saudi Arabia, which uses astronomical calculations to start months in a more predictable way. Using this calendar, sundown on Wednesday evening, December 13, will probably mark the beginning of Jumada al-Thani, also known as Jumada al-Akhirah, the sixth month of the Islamic calendar.

As mentioned above, the Geminid meteor shower will peak overnight from December 13 to 14, 2023. A good time to look will likely be after 8:30 PM EST the evening of Wednesday, December 13, until about 6 AM the morning of Thursday, December 14, when the first hints of dawn will begin to interfere. 2 to 3 AM will be when the radiant will reach its highest in the sky. Under ideal conditions this meteor shower is predicted to peak at about 150 visible meteors per hour. This meteor stream gets its name because the meteors appear to radiate out from near the constellation Gemini.

Thursday evening, December 14, 2023, will be the last evening that the planet Mercury will be above the west-southwestern horizon as evening twilight ends (at 5:50 PM EST). The thin, waxing crescent Moon will appear 4 degrees above the southwestern horizon about 11 degrees to the upper left of Mercury. Mercury may be visible before evening twilight ends for a few more evenings, but will quickly fade in brightness as it becomes a thinner crescent and will move closer to the glow of dusk on its way to pass between the Earth and the Sun on December 22.

Saturday afternoon, December 16, 2023, at 1:53 PM EST, the Moon will be at perigee, its closest to the Earth for this orbit.

Sunday evening, December 17, 2023, the planet Saturn will appear 3 degrees from the waxing crescent Moon. Saturn will be to the upper right as evening twilight ends (at 5:51 PM EST) and will swing clockwise around the Moon, setting first on the west-southwestern horizon a little more than 5 hours later (at 10:04 PM).

Tuesday afternoon, December 19, 2023, the waning Moon will appear half-full as it reaches its last quarter at 1:39 PM EST.

Thursday evening, December 21, 2023, at 10:27 PM EST, will be the winter solstice. This will be the day with the shortest period of daylight (9 hours, 26 minutes, 13 seconds long). Worldwide, there are number of festivals associated with the winter solstice, including Yule and the Chinese Dongzhi Festival.

Europeans have used two main ways to divide the year into seasons and define winter. The old Celtic calendar used in much of pre-Christian Europe considered winter to be the quarter of the year with the shortest periods of daylight and the longest periods of night, so that winter started around Halloween and ended around Groundhog Day (hence the origin of these traditions). However, since it takes time for our planet to cool off, the quarter year with the coldest average temperatures starts later than the quarter year with the shortest days. In our modern calendar we approximate this by having winter start on the winter solstice and end on the spring equinox. For the Washington, DC area at least, the quarter year with the coldest average temperatures actually starts the first week of December and ends the first week of March.

Solar noon on Thursday, December 21, to solar noon on Friday, December 22, 2023, will be the longest solar day of the year, 24 hours 29.8 seconds long. In this sense, the "shortest day of the year" is also the "longest day of the year!"

Thursday night into Friday morning, December 21 to 22, 2023, the bright planet Jupiter will appear near the waxing gibbous Moon. Jupiter will be 8 degrees to the lower left of the Moon as evening twilight ends (at 5:53 PM EST). The Moon will reach its highest in the sky for the night 2 hours later (at 7:53 PM) with Jupiter 7 degrees to the left. By the time the Moon sets on the west-northwestern horizon (at 2:50 AM) the Moon will be 4 degrees to the upper left of the Moon.

Friday afternoon, December 22, 2023, the planet Mercury will be passing between the Earth and the Sun as seen from the Earth, called inferior conjunction. Planets that orbit inside of the orbit of Earth can have two types of conjunctions with the Sun, inferior (when passing between the Earth and the Sun) and superior (when passing on the far side of the Sun as seen from the Earth). Mercury will be shifting from the evening sky to the morning sky and will begin emerging from the glow of the dawn on the east-southeastern horizon in late December (depending upon viewing conditions).

By Friday evening, December 22, 2023, the waxing gibbous Moon will have shifted to the other side of the bright planet Jupiter, with Jupiter appearing 6.5 degrees to the upper right of the Moon. Jupiter will appear to shift clockwise around the Moon, moving father away as the night progresses.

Saturday evening into Sunday morning, December 23 to 24, 2023, the Pleiades star cluster will appear near the waxing gibbous Moon. The Pleiades will be about 6 degrees to the lower left as evening twilight ends (at 5:54 PM EST) and will shift clockwise around the Moon, appearing about 4 degrees to the upper left by the time the Moon reaches its highest in the sky (at 9:34 PM). By the time the Moon sets on the west-northwestern horizon (at 5:11 AM) the Pleiades will be less than 2 degrees to the upper right of the Moon. Due to the glare of the nearly full Moon, it may be difficult to see the Pleiades without very clear, dark skies or binoculars.

The full Moon after next will be Tuesday evening, December 26, 2023, at 7:33 PM EST. This will be on Wednesday in Coordinated Universal Time (UTC) and for most of Eurasia, Africa, and Australia. Many commercial calendars are based on UTC and will show this full Moon on Wednesday. The Moon will appear full for 3 days around this time, from Monday evening to Thursday morning.