December 2019: The Next Full Moon is the Cold Moon

The next full Moon is the Cold Moon, Oak Moon, Moon before Yule, Long Night Moon, Uduvapa Poya, the Karthikai Deepam Moon and the Chang'e Moon.

The Moon will be full just after midnight on Thursday morning, Dec. 12, 2019, appearing "opposite" the Sun (in Earth based longitude) at 12:12 AM EST. The Moon will appear full for about three days centered on this time, from Tuesday evening through Friday morning.

The Moon will appear full for about three days centered on this time, from Tuesday evening through Friday morning.

The Maine Farmer's Almanac first published Indian names for the full Moons in the 1930's. According to this almanac, the Algonquin tribes of what is now the northern and eastern United States named the full Moon in December or the last full Moon of the fall season the Cold Moon, due to the long, cold nights. An old European name for this Moon is the Oak Moon, a name that some believe ties back to ancient druid traditions of harvesting mistletoe from oak trees first recorded by the Roman historian Pliny the Elder in the 1st 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." Europeans also called this the Moon before Yule. Yule was a 3-day winter solstice festival. In the 10th Century King Haakon I associated Yule with Christmas as part of the Christianization of Norway, and this association is now common throughout Europe.

As the full Moon closest to the winter solstice, Europeans named this the Long Night Moon. The plane of the Moon's orbit around the Earth nearly matches the plane of the Earth's orbit around the Sun. When the path of the Sun appears lowest in the sky for the year, the path of the full Moon opposite the Sun appears highest in the sky. For the Washington, DC, area, on Wednesday evening, December 11, 2019, moonrise will be at 4:35 PM, sunset will be 11 minutes later at 4:46 PM, the Moon will reach its highest point of the night (72.2 degrees above the horizon) just after midnight at 12:02 AM on Thursday morning, sunrise will be at 7:17 AM, and moonset will be 16 minutes later at 7:33 AM EST. The Moon will be in the sky for a total of 14 hours 58 minutes, with 14 hours 13 minutes of this when the Sun is down, making Wednesday night into Thursday morning, December 11 to 12, 2019, the longest full Moon night of the year.

Every full Moon (Poya) is a holiday in Sri Lanka. This full Moon is Uduvapa Poya, also known as Uposatha Poya and Sanghamitta Day, celebrating the planting in 288 BCE of a sapling from the sacred Bodhi Tree in the city of Anuradhapura by Princess Sanghamitta, who help spread the teachings of Buddha in Sri Lanka. Princess Sanghamitta was the eldest daughter of the Emperor Ashoka.

Karthikai Deepam, also known as Karthikai Vilakkidu or Thrikarthika, is a festival of lights that is observed by Hindus of Tamil Nadu, Sri Lanka, and Kerala. This festival is celebrated when the nearly full Moon lines up with the Pleiades constellation (Karttikai), and will be celebrated this year on December 10, 2019.

We could also call this the Chang'e Moon, after the two Chinese lunar landers that launched in December of 2013 and 2018. The Chang'e 3 lander and Yutu rover launched on December 1 and landed on the Moon on December 14 2013. The Chang'e 4 lander and Yutu-2 rover launched on December 7, 2018 and landed on January 3, 2019. These missions are named after the Chinese goddess of the Moon, Chang'e, who lived on the Moon with her pet jade rabbit, Yutu.

In most 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 eleventh month of the Chinese calendar and Kislev in the Hebrew calendar. Hanukkah begins on the 25th of Kislev (sundown on Sunday, December 22) and ends on the 2nd of Tevet (sundown on Monday, December 30, 2019).

In the Islamic calendar the months start with the first sighting of the waxing crescent Moon a few days after the New Moon. This full Moon is near the middle of Rabi' al-Thani, the fourth month of the Islamic year.

As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon.

As for other celestial events between now and the full Moon after next:

As autumn ends and winter begins, the daily periods of sunlight reach their shortest and then begin to lengthen again. The length of a solar day varies throughout the year. Around the solstices the solar day is slightly longer than the 24 hour average that our clocks use. Because of this, the earliest sunsets of the year occur before the winter solstice and the latest sunrises of the year (ignoring Daylight Savings Time) occur after the solstice. For the Washington, DC area (and similar latitudes at least), the earliest sunset of the year will occur on Saturday, December 7, 2019, at 4:46 PM EST. Rounded to the nearest minute, sunset will be at 4:46 PM from Sunday, December 1 through Friday, December 13, 2019. On the day of the next full Moon (December 12), the period of daylight will last 9 hours, 29 minutes, 2 seconds. Morning twilight will begin at 6:14 AM, sunrise will be at 7:17 AM, the Sun will reach a maximum altitude of 28.0 degrees at 12:02 PM, sunset will be at 4:46 PM (one of the earliest sunsets of the year), and evening twilight will end at 5:50 PM. On the day of the winter solstice, December 21, 2019, the period of daylight will last 9 hours, 26 minutes, 14 seconds. Morning twilight will begin at 6:19 AM, sunrise will be at 7:23 AM, the Sun will reach a maximum altitude of 27.7 degrees at 12:06 PM (its lowest maximum for the year), sunset will be at 4:49 PM, and evening twilight will end at 5:53 PM.

After the day of the solstice, the daily periods of sunlight gradually will begin to increase again. The solar day from solar noon on December 22 to solar noon on December 23 will be the longest solar day of the year, about 30 seconds longer than 24 hours. For the Washington, DC area (and similar latitudes at least), The latest sunrise of the year (ignoring the 1-hour shift due to Daylight Savings Time) will be on January 5, 2020. By the day of the full Moon after next (January 10, 2020), the period of daylight will last 9 hours, 37 minutes, 55 seconds. Morning twilight will begin at 6:24 AM, sunrise will be at 7:27 AM, the Sun will reach a maximum altitude of 29.2 degrees at 12:16 PM, sunset will be at 5:05 PM, and evening twilight will end at 6:07 PM.

On the evening of the full Moon on December 12, 2019, as evening twilight ends, the brightest planet in the sky will be Venus, appearing as the evening star in the southwest at about 10 degrees above the horizon, with Saturn appearing to the right of Venus. Venus and Saturn will have appeared at their closest, about 2 degrees apart, the previous two evenings. Jupiter will have already set, but should be visible about 30 minutes after sunset in the west-southwest. No particularly bright star will appear nearly directly overhead. The bright star will be Deneb, one of the three stars in the Summer Triangle, will appear about 62 degrees above the northwest horizon. As the month progresses Saturn and the background of stars will appear to shift towards the west, while Venus will appear to shift the other direction, higher in the sky each night. Towards the end of December Saturn will be setting by the time evening twilight ends. By the evening of the full Moon after next, January 10, 2020, bright Venus will appear in the southwest at about 19 degrees above the horizon. The bright stars from the local arm of our home galaxy in the constellation Orion will appear rising in the east.

On the morning of the full Moon on December 12, 2019, as morning twilight begins, the planet Mercury will appear about 2 degrees above the horizon in the east-southeast, while the planet Mars will appear about 18 degrees above the southeast horizon. As the month progresses, Mars and the background of stars will appear to shift towards the west, while Mercury shifts towards the east until it is lost in the glow of dawn. By the morning of the full Moon after next on January 10, 2020, Mars will appear about 20 degrees above the horizon in the southeast with the bright star Antares appearing below Mars.

Several meteor showers will peak between now and the full Moon after next, most notably the Geminids and Quadrantids. The Geminid meteor shower will begin to show a few meteors around December 4 and will ramp up to a broad peak the morning of December 14, tapering off by December 17, 2019. This year the light of the nearly full Moon will reduce the number of meteors that will be visible, so conditions will not be good for viewing this meteor shower.

Although the Quadrantid meteor shower will begin to show a few meteors around December 28, 2019, it is expected to have a short, sharp peak the morning of January 4, 2020, then quickly taper off by January 12. This year, on the morning of the expected peak, the Moon will set just around the time the radiant (the direction from which the meteors appear to be spreading out from) is rising. The time between moonset and when the sky starts showing the first signs of dawn should be the best time to look for these meteors. Zenithal hourly rate (ZHR) is the predicted maximum number of meteors an ideal observer would see with no interference from the Moon or city lights, with perfectly clear skies (reference limiting magnitude +6.5), with the shower radiant directly overhead, and after the observer's eyes have had 30 to 45 uninterrupted minutes to adjust to the darkness (no checking your cell phone to see how long it has been). Under these ideal viewing conditions (almost impossible to get), the Quadrantids are predicted to peak at about 3:20 AM EST with a ZHR of between 60 and 200 meteors per hour (nominally 120 meteors per hour). The peak is expected to be narrow, with the ZHR about half the peak rate 2 hours before or after the peak. The Quadrantids are caused by dust hitting the Earth's atmosphere at 41 km/sec (92,000 miles per hour). The parent body for this meteor shower is thought to be 2003 EH1, which appears to be an extinct comet that may have broken off from the comet C/1490 Y1 observed in 1490 by Chinese, Japanese, and Korean astronomers.

Even though they are not usually visible, I include in these Moon missives information about Near Earth Objects (mostly asteroids) that may pass the Earth within 5 lunar distances, because I find it interesting that we have discovered so many. Most of these passes are predicted to occur early in the period covered by this Moon Missive because we are constantly finding new objects just before they pass by. On Friday morning, December 6, 2019, at 6:45 AM EST (2019-Dec-06 11:45 UTC), Near Earth Object (2019 XN), between 8 and 18 meters (26 to 59 feet) in size, will pass the Earth at 2.4 lunar distances, traveling at 9.74 kilometers per second (21,800 miles per hour).

Sometime between now and December 14, 2019 (2019-Dec-06 16:26 UTC with 7 days 22 hours 54 minutes uncertainty), Near Earth Object (2016 XA2), between 127 and 284 meters (417 to 933 feet) in size, will pass the Earth at between 0.9 and 133.1 lunar distances (nominally 66.9), traveling at 28.76 kilometers per second (64,300 miles per hour).

Sometime around Saturday, December 7, 2019 (2019-Dec-07 20:32 UTC with 10 hours 48 minutes uncertainty), Near Earth Object (2009 WY7), between 40 and 90 meters (132 to 295 feet) in size, will pass the Earth at between 2.9 and 90.2 lunar distances (nominally 37.7), traveling at 16.54 kilometers per second (37,000 miles per hour).

For the Washington, DC area (and similar latitudes at least), the earliest sunset of the year will occur on Saturday, December 7, 2019, at 4:46 PM EST.

Sometime around midnight between Sunday and Monday, December 8 to 9, 2019 (2019-Dec-09 04:54 UTC with 15 minutes uncertainty), Near Earth Object (2019 XY), between 7 and 15 meters (22 to 49 feet) in size, will pass the Earth at between 3.1 and 3.2 lunar distances (nominally 3.2), traveling at 13.07 kilometers per second (29,200 miles per hour).

On Monday afternoon, December 9, 2019, at 1:47 PM EST (2019-Dec-09 18:47 UTC with 1 minute uncertainty), Near Earth Object (2019 WO2), between 27 and 59 meters (87 to 195 feet) in size, will pass the Earth at between 4.7 and 4.8 lunar distances (nominally 4.7), traveling at 7.59 kilometers per second (16,980 miles per hour).

On the evenings of Tuesday and Wednesday, December 10 and 11, 2019, bright Venus will appear less than two degrees from Saturn. Try looking in the southwest as evening twilight ends (around 5:50 PM EST for the Washington, DC area).

On Tuesday evening into Wednesday morning, December 10 to 11, 2019, the bright star Aldebaran will appear near the full Moon. As evening twilight ends on Tuesday evening, Aldebaran will appear about 6.5 degrees below and to the left of the Moon in the east. By the time morning twilight begins on Wednesday morning, Aldebaran will appear about 2.5 degrees to the left of the setting Moon in the west-northwest.

As mentioned above, the next full Moon will be just after midnight early Thursday morning, December 12, 2019, at 12:12 AM EST.

Although the light of the nearly full Moon will interfere, the best opportunity to view the peak of the annual Geminid meteor shower should be after midnight but before the sky begins showing signs of dawn early on Saturday morning, December 14, 2019. It will be difficult to see these meteors unless you are in a very dark location far from city lights, with a clear view of a large part of the sky, and no clouds or haze.

Saturday evening, December 14, 2019, the bright star appearing about 8 degrees above the waning gibbous Moon will be Pollux, one of the twins in the constellation Gemini. For the Washington, DC area, the Moon will rise in the east-northeast at 7:20 PM EST, and the Moon and Pollux will appear to separate as they rise higher in the sky.

Monday night into Tuesday morning, December 16 to 17, 2019, the bright star appearing to the lower right of the waning gibbous Moon will be Regulus. For the Washington, DC area, the Moon will rise in the east-northeast at 9:37 PM EST and Regulus will rise about 17 minutes later. The Moon will reach its highest in the sky Tuesday morning at 4:45 AM and morning twilight will begin at 6:17 AM.

Wednesday afternoon, December 18, 2019, at 3:26 PM EST, the Moon will be at perigee, its closest to the Earth for this orbit.

Wednesday night, December 18, 2019, the waning Moon will appear half-full as it reaches its last quarter at 11:57 PM EST (right around the time the Moon is rising for the Washington, DC area).

On Saturday morning, December 21, 2019, the bright star about 8 degrees to the right of the waning crescent Moon will be Spica. For the Washington, DC area, the Moon will rise in the east at 2:15 AM EST and morning twilight will begin around 6:19 AM.

Saturday night, December 21, 2019, at 11:19 PM EST, will be the winter solstice, the astronomical end of fall and start of winter. 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. 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. The winter solstice is the day with the shortest period of sunlight (although it is one of the longer solar days of the year). Worldwide, there are number of festivals associated with the winter solstice, including Yule and the Chinese Dongzhi Festival.

The relatively minor Ursid meteor shower should peak Monday morning, December 23, 2019, expected to produce about 10 meteors per hour under ideal viewing conditions (although this shower has occasional and unpredictable outbursts up to about 50 per hour). For those of us in urban environments with interference from city lights, it is not likely we will be able to see these meteors, but if you happen to be in a dark place with clear skies, the best time to look should be after midnight but before moonrise (at 4:33 AM EST for the Washington, DC area).

Monday morning, December 23, 2019, the planet Mars will appear to the upper right of the waning crescent Moon. For the Washington, DC area, the Moon will rise in the east-southeast at 4:33 AM EST and morning twilight will begin around 6:20 AM.

Just after midnight on Thursday morning, December 26, 2019, at 12:13 AM EST, will be the new Moon, when the Moon passes between the Earth and the Sun and will not be visible from most of the Earth. For the region of the Earth from the eastern-most parts of the Arabian peninsula and Africa across Asia and the Indian Ocean to northern Australia and Papua New Guinea, the Moon will be visible by partially blocking the disk of the Sun, causing a partial eclipse and for a narrow stripe through the center of this region an annual solar eclipse.

Generally, the day of or the day after the New Moon marks the start of the new month for most lunisolar calendars. The twelfth month of the Chinese calendar starts on Thursday, December 26, 2019 (at midnight in China's time zone, which is 13 hours ahead of EST).

On Friday evening, December 27, 2019, just about the time evening twilight ends (at 5:56 PM EST for the Washington, DC area, you might be able to see the thin, waxing crescent Moon about 3 degrees above the horizon, with the planet Saturn to the lower right. To see them you will need a very clear view too low on the horizon in the west-southwest. In the Islamic calendar the months start with the first sighting of the waxing crescent Moon after the New Moon. The sighting of the crescent Moon will probably mark the beginning of Jumada al-awwal.

On Friday, December 27, 2019, the planet Jupiter will be passing on the far side of the Sun as seen from the Earth, called conjunction. Because Jupiter orbits outside of the orbit of Earth, it will be shifting from the evening sky to the morning sky and will begin emerging from the glow of dawn on the eastern horizon in January 2020.

For the Hebrew calendar, the start of each month was at one time based on the observation of the crescent Moon (as the Islamic calendar still is). The Hebrew calendar now follows a fixed pattern finalized in the 12th Century. The Hebrew month of Tevet starts at sundown on Saturday, December 28, 2019.

Saturday evening, December 28, 2019, the brightest of the planets, Venus, will appear about 2 degrees above the waxing crescent Moon. For the Washington, DC area, the Moon will appear about 12 degrees above the southwestern horizon as evening twilight ends at 5:57 PM EST and will set in the west-southwest by 7:22 PM.

On Wednesday evening, January 1, 2020, at 8:31 PM EST, the Moon will be at apogee, its farthest from the Earth for this orbit.

On Thursday morning, January 2, 2019, at around 9 AM EST (2020-Jan-02 16:08 UTC with 1 hour 16 minutes uncertainty), Near Earth Object (2019 AE3), between 10 and 22 meters (32 to 71 feet) in size, will pass the Earth at between 4.0 and 5.7 lunar distances (nominally 4.8), traveling at 8.24 kilometers per second (18,400 miles per hour).

On Thursday night, January 2, 2020, the Moon will appear half-full as it reaches its first quarter at 11:45 PM EST (shortly before it sets in the west for the Washington, DC area).

Early Thursday morning, January 5, 2020, the Earth will be at perihelion, the closest we get to the Sun in our orbit. Between perihelion and 6 months later at aphelion there is about a 6.7% difference in the intensity of the sunlight reaching the Earth, one of the reasons the seasons in the Southern hemisphere are more extreme than in the Northern Hemisphere. Perihelion is also when the Earth is moving the fastest in its orbit around the Sun, so if you run east at local midnight, you will be moving about as fast as you can (in Sun-centered coordinates) for your location.

For the Washington, DC area (and similar latitudes, at least), sunrise on Thursday, January 5, 2019, will be the latest sunrise of winter (and would be the latest sunrise of the year if not for Daylight Savings Time). If it seems hard waking up in the morning around this time, this might be why (or at least it makes a good excuse).

On Tuesday evening into Wednesday morning, January 7 to 8, 2019, the bright star appearing near the waxing gibbous Moon will be Aldebaran. For the Washington, DC area, as evening twilight ends (at 6:05 PM EST), Aldebaran will appear to the right of the Moon. The Moon will reach its highest in the sky at 9:48 PM with Aldebaran to the lower right. Aldebaran will appear below the Moon when Aldebaran sets in the west-northwest on Wednesday morning at 4:33 AM.

On Friday, January 10, 2020, the planet Mercury will be passing on the far side of the Sun as seen from the Earth, called superior conjunction. Because Mercury orbits inside of the orbit of Earth, it will be shifting from the morning sky to the evening sky and will begin emerging from the glow of dusk on the western horizon in late January 2020.

The full Moon after next will be Friday afternoon, January 10, 2020, at 2:21 PM EST. Although not visible from most of the Americas, the Moon will be in the partial shadow of the Earth. For the side of the Earth that will be able to see the Moon, the slight dimming of the Moon should be barely noticeable. The bright star near the Moon will be Pollux.