December 2020: The Next Full Moon is the Wolf Moon

The Next Full Moon is the Wolf Moon, Ice Moon, Cold Moon, the Moon after Yule, the Long Night Moon, the Datta Jayanti Moon, Unduvap Poya, and the Chang'e Moon.

The next full Moon will be Tuesday evening, December 29, 2020, appearing opposite the Sun in Earth-based longitude at 10:28 PM EST. This is close enough to midnight that the full Moon will be on the next day in Coordinated Universal Time (UTC), so many calendars will show the full Moon on December 30, 2020. The Moon will appear full for about three days around this time, from Monday evening through Thursday morning.

In the 1930's the Maine Farmer's Almanac began publishing "Indian" names for the full Moons, tying these names to the European months. I tie these Moon names to the seasons rather than months (for reasons I have explained in earlier postings), so the names I use will be off a month from other sources until the summer of 2021. By season, as the first full Moon of winter, the Algonquin tribes of what is now the northern and eastern United States named this the Wolf Moon, from the packs of wolves that howled hungrily outside the villages amid the cold and deep snows of winter. Another name is the Ice Moon. By month the full Moon in December is called the Cold Moon.

Europeans called this the Moon after Yule, a 3-day winter solstice festival in pre-christian Europe. In the 10th Century King Haakon I associated Yule with Christmas as part of the Christianization of Norway, and this association has spread throughout the countries that follow European traditions. Another English name for this Moon is the Old Moon.

As the full Moon closest to the winter solstice, this is 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 Tuesday evening, December 29, 2020, moonrise will be at 4:32 PM, sunset will be 23 minutes later at 4:55 PM, the Moon will reach its high point for the night (75.8 degrees above the horizon) just after midnight at 12:15 AM on Wednesday morning, sunrise will be at 7:26 AM, and moonset will be 33 minutes later at 7:59 AM EST. The Moon will be in the sky for a total of 15 hours 27 minutes, with 14 hours 31 minutes of this when the Sun is down, making Tuesday evening into Wednesday morning, December 29 to 30, 2020, the longest full Moon night of the year.

For Hindus, this full Moon is Datta Jayanti, commemorating the birth day of the Hindu god Dattatreya (Datta). For the Buddhists of Sri Lanka, this is Unduvap Poya. The Buddha is said to have attained Enlightenment by meditating under a Bodhi Tree in India. In the 3rd century BCE, Sangamitta Theri, the daughter of Emperor Asoka and founder of an order of Buddhist nuns in Sri Lanka, brought a branch of this tree to Sri Lanka. The sapling was planted in 288 BC by King Devanampiya Tissa in the Mahamevnāwa Park in Anuradhapura, Sri Lanka, where it still grows today, making it the oldest living human-planted tree with a known planting date.

We could also call this the Chang'e Moon, after the three Chinese lunar landers that launched this time of year in 2013, 2018, and 2020. These missions get their name from the Chinese goddess of the Moon, Chang'e, who lived on the Moon with her pet rabbit, Yutu. The Chang'e 3 lander and its companion Yutu rover launched on December 1 and landed on the Moon on December 14 2013. The Chang'e 4 lander and its companion Yutu-2 rover launched December 7, 2018 and landed January 3, 2019. The Chang'e 5 lunar sample return mission launched on November 23 (in UTC, November 24 in China's time zone) and returned its samples to the Earth on December 16, 2020, humanity's first lunar sample return since 1976.

In most 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 eleventh month of the Chinese calendar, Tevet in the Hebrew calendar, and Jumada al-awwal in the Islamic calendar.

As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Stay warm, but take advantage of these early nightfalls to get out, look up, and share the wonders of the sky!

As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Stay warm, but take advantage of these early nightfalls to get out, look up, and share the wonders of the sky!

Here is a summary of celestial events between now and the full Moon after next (with angles and times based on the location of NASA Headquarters in Washington, DC):

As winter begins in the northern hemisphere, the daily periods of sunlight will begin lengthening. Using the location of NASA Headquarters, on the day of the full Moon (Tuesday, December 29, 2020), morning twilight will begin at 6:23 AM EST, sunrise will be at 7:26 AM, solar noon will be at 12:10:25 PM when the Sun will reach its maximum altitude of 27.98 degrees, sunset will be at 4:55 PM, and evening twilight will end at 5:58 PM.

Ever since 2007 when Congress moved the start of Daylight Savings Time from the end of October to the beginning of November, the latest sunrises of the year (in DST) have been occurring in late October and early November. Around the solstices the solar days are 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 DC area, Monday and Tuesday, January 4 and 5, 2021, are tied for the latest (non-Daylight Savings Time) sunrises of the year, with sunrises at 7:26:56 AM EST.

By the day of the full Moon after next (Thursday, January 28, 2021), morning twilight will begin at 6:17 AM EST, sunrise will be at 7:17 AM, solar noon will be at 12:21:06 PM when the Sun will reach its maximum altitude of 33.14 degrees, sunset will be at 5:25 PM, and evening twilight will end at 6:26 PM.

On the evening of this full Moon (December 29, 2020), as evening twilight ends (at 5:58 PM EST), the bright planet Jupiter will appear 7.5 degrees above the horizon in the west-southwest with the planet Saturn appearing less than 1 degree to the lower right of Jupiter. The planet Mars will appear about 58 degrees above the horizon in the southeast and will be the bright object that appears closest to directly overhead. The bright stars of the Orion–Cygnus Arm of our home galaxy will appear low on the horizon in the east.

As the lunar cycle progresses, these planets and the background of stars will appear to shift towards the west. Mars will remain high and visible, having reached its closest and brightest for the year on October 13, 2020. The planet Mercury will be the exception, appearing to shift towards the east each evening. After January 4, 2021, Mercury will begin to emerge from the glow of dusk in the west-southwest about 30 minutes after sunset. Jupiter and Saturn will appear to separate and shift lower towards the horizon. After January 7, 2021, Saturn will have set by the time evening twilight ends. Between January 8 and 11, Mercury will appear to pass first Saturn and then Jupiter as it shifts away from the horizon, visible low in the west-southwest before evening twilight ends. After January 10, Jupiter will have set by the time evening twilight ends. January 13 will be the first evening that Mercury will be above the horizon at the time evening twilight ends.

By the evening of the full Moon after next on Thursday, January 28, 2021, as evening twilight ends (at 6:26 PM EST), the planet Mars will appear about 67 degrees above the horizon in the south-southwest and will be the bright object that appears closest to directly overhead. The planet Mercury will appear about 4 degrees above the horizon in the west-southwest. The bright stars of the Orion–Cygnus Arm of our home galaxy will appear in the southeastern sky.

On the morning of December 29, 2020, as morning twilight begins (at 6:23 AM EST), the bright planet Venus will appear in the east-southeast about 5 degrees above the horizon. The bright star appearing closest to overhead will be Arcturus, which will be about 63 degrees above the horizon in the southeast.

As the lunar cycle progresses, the background of stars will appear to shift towards the west each morning while the planet Venus will appear to shift slowly towards the east, dimming slightly as it moves farther away from the Earth and towards the far side of the Sun. After the morning of January 13, 2021, Venus will be below the horizon at the time morning twilight begins, but should still be visible in the glow of dawn in the east-southeast until about 30 minutes before sunrise.

By the morning of the full Moon after next on January 28, 2021, as morning twilight begins (at 6:17 AM EST), the planet Venus will not rise until about 39 minutes before sunrise, making it difficult to see in the glow of dawn in the east-southeast. The bright star appearing closest to overhead will be Arcturus, appearing about 69 degrees above the horizon in the south-southwest.

This year moonlight will interfere with viewing the annual Quadrantid meteor shower, expected to be active from December 28, 2020, through January 12, 2021, peaking on the morning of January 3, 2021. Under ideal conditions, the Quadrantids would be one of the three best meteor showers of the year, but not this year.

And here is a day-by-day listing of celestial events between now and the full Moon after next (again based on the location of NASA Headquarters in Washington, DC):

Monday evening, December 21, 2020, will be when the bright planet Jupiter and the fainter planet Saturn (the two largest planets in the Solar System) will appear nearest to each other, called a Great Conjunction. They will appear about 1/5 of the apparent diameter of the Moon (1/10 of a degree) apart. As evening twilight ends (at 5:53 PM EST) they will appear about 12 degrees above the southwestern horizon. See https://www.nasa.gov/feature/the-great-conjunction-of-jupiter-and-saturn for more information.

On Monday evening, December 21, 2020, the waxing Moon will appear half-full as it reaches its first quarter at 6:41 PM EST.

Wednesday morning, December 23, 2020, will be the morning when the bright planet Venus appears closest to the bright star Antares. To see them you will need a clear view of the horizon about halfway between east-southeast and southeast. As morning twilight begins (at 6:21 AM EST) Venus will appear about 6 degrees above the horizon with Antares appearing about 6 degrees to the lower right of Venus and about 3 degrees above the horizon.

On Wednesday evening into early Thursday morning, December 23 to 24, 2020, the bright planet Mars will appear near the waxing gibbous Moon. As evening twilight ends (at 5:54 PM EST) the Moon will appear 49 degrees above the southeastern horizon with Mars about 6 degrees above the Moon. The Moon will reach its high point for the night at 7:35 PM with Mars to the upper right. Mars will set first (to the right of the Moon on the western horizon) Thursday morning at 1:59 AM.

Thursday morning, December 24, 2020, at 11:32 AM EST, the Moon will be at apogee, its farthest from the Earth for this orbit.

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. Sometime around Christmas Eve, 2020 (2020-Dec-24 12:41 UTC with 3 days, 1 hour, 28 minutes uncertainty), Near Earth Object (2011 CL50), between 8 and 18 meters (26 to 59 feet) across, will pass the Earth at between 1.2 and 5.5 lunar distances (nominally 3.1), traveling at 3.36 kilometers per second (7,510 miles per hour).

On Christmas Eve, Thursday evening, December 24, 2020, at about 7:54 PM EST (2020-Dec-25 00:54 UTC with 2 minutes uncertainty), Near Earth Object (2020 YM1), between 3 and 7 meters (10 to 23 feet) across, will pass the Earth at between 1.6 and 1.7 lunar distances (nominally 1.7), traveling at 3.24 kilometers per second (7,250 miles per hour).

Friday evening, December 25, 2020 (the evening of Christmas Day), will be the last evening when the bright planet Jupiter and the fainter planet Saturn will appear nearer to each other than the apparent diameter of the Moon. As evening twilight ends (at 5:55 PM EST) they will appear about 9 degrees above the southwestern horizon.

Saturday evening into Sunday morning, December 26 to 27, 2020, the bright star Aldebaran will appear near the waxing gibbous Moon. They will appear more than 10 degrees apart as evening twilight ends on Saturday evening, but by about 2 AM EST Sunday morning Aldebaran will appear about 8 degrees to the upper left of the Moon. By the time the Moon sets in the west-northwest Sunday morning (at 5:04 AM) Aldebaran will appear about 6 degrees to the left of the Moon.

Sometime around Sunday, December 27, 2020 (2020-Dec-27 07:44 UTC with 1 day, 9 hours, 43 minutes uncertainty), Near Earth Object (2016 AF2), between 7 and 16 meters (23 to 51 feet) across, will pass the Earth at between 3.8 and 11.2 lunar distances (nominally 7.3), traveling at 5.35 kilometers per second (11,970 miles per hour).

By Sunday evening into Monday morning, December 27 to 28, 2020, the waxing gibbous Moon will appear to have shifted to the other side of the bright star Aldebaran. As evening twilight ends (at 5:57 PM EST) Aldebaran will appear about 5 degrees to the right of the Moon, and the pair will appear to separate as the night progresses. Aldebaran will set first in west-northwest Monday morning at 5:10 AM.

As mentioned above the next full Moon will be Tuesday evening, December 29, 2020, appearing opposite the Sun in Earth-based longitude at 10:28 PM EST.

On Wednesday evening through Thursday morning, December 30 to 31, 2020, the bright star Pollux will appear near the full Moon. As evening twilight ends (at 5:59 PM EST), Pollux will appear about 6 degrees (12 lunar diameters) to the left of the Moon about 4 degrees above the horizon in the east-northeast. The Moon will reach its high point for the night Thursday morning at 1:09 AM with Pollux appearing about 4 degrees above the Moon. Pollux will appear about 5 degrees to the upper right of the Moon in the west-northwest as morning twilight begins at 6:23 AM.

On Saturday morning, January 2, 2021, the Earth will be at perihelion, the closest the Earth gets to the Sun in our orbit. Between perihelion and 6 months later when the Earth is at its farthest from the Sun (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 its 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 (at least in Sun-centered coordinates) for your location. To view Dr. C. B. Boff's proclamation on this topic visit http://cbboff.org/Proclamations/ (dated now, as it was prepared for the new millennium).

On Saturday night into Sunday morning, January 2 to 3, 2021, the bright star Regulus will appear near the waning gibbous Moon. Regulus will rise in the east-northeast to the right of the Moon (at 8:44 PM EST). The Moon will reach its high point for the night Sunday morning (at 3:47 AM), and morning twilight will begin around 6:24 AM.

Early morning on Sunday, January 3, 2021, the annual Quadrantid meteor shower is expected to peak. This year moonlight will interfere with viewing these meteors.

On Sunday morning, January 3, 2021, at around 5 AM EST (2021-Jan-03 10:02 UTC with 19 minutes uncertainty), Near Earth Object (2020 YA1), between 12 and 27 meters (40 to 89 feet) across, will pass the Earth at between 4.0 and 4.1 lunar distances (nominally 4.0), traveling at 3.69 kilometers per second (8,260 miles per hour).

For latitudes similar to the Washington, DC area, ignoring daylight savings time, Monday and Tuesday, January 4 and 5, 2021, are tied for the latest sunrises of the year (with sunrises at 7:26:56 AM EST).

Monday evening, January 4, 2021, will be the first evening the planet Mercury will be above the horizon about 30 minutes after sunset, an approximation of when Mercury may begin to be visible against the glow of dusk in the west-southwest after sunset.

Wednesday morning, January 6, 2021, the waning Moon will appear half-full as it reaches its last quarter at 4:37 AM EST.

Thursday morning, January 7, 2021, the bright star Spica will appear to the left of the waning crescent Moon. The Moon will rise after Spica in the east at 1:15 AM EST, with Spica to the right, and the pair will appear to separate as the morning progresses, with morning twilight starting at 6:24 AM.

Thursday evening, January 7, 2021, will be the last evening the planet Saturn will be above the horizon as evening twilight ends.

Each evening over the extended weekend from Friday evening, January 8, to Monday evening, January 11, 2021, the planet Mercury will appear to pass first by Saturn and then by Jupiter as it shifts away from the horizon, visible each evening low in the west-southwest and setting before evening twilight ends.

Saturday morning, January 9, 2021, at 10:39 AM EST, the Moon will be at perigee, its closest to the Earth for this orbit.

On Sunday morning, January 10, 2021, the bright star Antares will appear about 7 degrees to the right of the thin, waning crescent Moon. The Moon will rise after Antares in the east-southeast (at 4:53 AM EST) and morning twilight will begin about 1.5 hours later (at 6:24 AM).

Sunday evening, January 10, 2021, will be the last evening the planet Jupiter will be above the horizon as evening twilight ends.

Monday morning, January 11, 2021, if you have a very clear view of the horizon in the east-southeast, you might be able to see the bright planet Venus near the thin, waning crescent Moon. Venus will rise after the Moon (at 6:16 AM EST). Morning twilight begins 8 minutes later (at 6:24 AM EST), with the Moon appearing only about 2 degrees above the horizon and Venus about 5 degrees to the lower left. They will shift higher in the sky but also become more difficult to see as the sky brightens with dawn.

At midnight between Tuesday night and Wednesday morning, January 12 to 13, 2021, will be the new Moon, when the Moon passes between the Earth and the Sun and is not visible from the Earth.

Wednesday morning, January 13, 2021, will be the last morning that the bright planet Venus will be above the horizon at the time morning twilight begins. Venus should still be visible in the glow of dawn after it rises in the east-southeast until about 30 minutes before sunrise.

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 Wednesday, January 13, 2021 (at midnight in China's time zone, which is 13 hours ahead of EST). Sundown on Wednesday also marks the start of Shevat in the Hebrew calendar. 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 the sixth month of the year, Jumada al-Thani, also known as Jumada al-Akhirah or Jumada al-Akhir, will begin at sunset on Wednesday, January 13, 2021.

Wednesday evening, January 13, 2021, before 30 minutes after sunset, you might be able to see the thin waxing crescent Moon, Saturn, Jupiter, and Mercury, low in the west-southwest. I think the Moon will be very difficult to see, as it will be setting 30 minutes after sunset (at 5:38 PM EST), but if you can see it before it sets in the west-southwest (perhaps with binoculars), you might be able to also spot Saturn, Jupiter, and Mercury in an arc above the Moon. If you use binoculars, be sure to wait until you are sure the Sun has set. Mercury will be the highest in the sky, and Wednesday evening, January 13, 2021, will be the first evening that Mercury will be above the horizon at the time evening twilight ends.

By Thursday evening, January 14, 2021, the thin, waxing crescent Moon will have shifted to form a rough line with Mercury, Jupiter, and Saturn just above the horizon in the west-southwest. For the Washington DC area, at 5:40 PM EST (30 minutes after sunset), the Moon will be to the upper left about 10 degrees above the horizon, then Mercury to the lower right at 6 degrees above the horizon, Jupiter at 3 degrees, and Saturn at 1 degree above the horizon. Saturn will set first (at 5:48 PM EST), Jupiter next (at 6:02 PM), evening twilight will end (at 6:12 PM), Mercury will set (at 6:21 PM), and the Moon will set last (at 6:47 PM).

Sometime in mid-January, 2021 (2021-Jan-16 10:49 UTC with 7 days, 5 minutes uncertainty), Near Earth Object (2013 AS76), between 56 and 124 meters (182 to 407 feet) across, will pass the Earth at between 4.7 and 183.5 lunar distances (nominally 74.0), traveling at 12.51 kilometers per second (27,980 miles per hour).

On Wednesday afternoon, January 20, 2021, the Moon will appear half-full as it reaches its first quarter at 4:02 PM EST.

On Wednesday evening into early Thursday morning, January 20 to 21, 2021, the bright planet Mars will appear above the half-full Moon. As evening twilight ends (at 6:17 PM EST), Mars will appear about 8 degrees to the upper right of the Moon. The pair will appear to shift gradually closer together until the Moon sets in the in the west-northwest on Thursday morning at 12:54 AM.

Thursday, January 21, 2021, at 8:11 AM EST, the Moon will be at apogee, its farthest from the Earth for this orbit.

By Thursday evening, January 21, 2021, the Moon will appear to have shifted to about 9 degrees to the other side of the planet Mars, and the pair will continue to separate as the evening progresses.

Saturday evening, January 23, 2021, will be when the planet Mercury reaches its greatest angular separation from the Sun as seen from the Earth for this apparition (called greatest eastern elongation), appearing half-lit through a large enough telescope. Because the angle of the line between the Sun and Mercury and the horizon changes over time, when Mercury and the Sun appear farthest apart as seen from the Earth is not the same as when Mercury appears highest above the horizon in the west-southwest as evening twilight ends. This occurs the next evening.

On Saturday evening, January 23, 2021, at 9:26 PM EST, the planet Saturn will be passing on the far side of the Sun as seen from the Earth, called conjunction. Saturn will begin emerging from the glow of the dawn on the eastern horizon around February 7, 2021 (depending upon viewing conditions).

On Saturday evening into Sunday morning, January 23 to 24, 2021, the bright star Aldebaran will appear below the waxing gibbous Moon. As evening twilight ends (at 6:21 PM EST) Aldebaran will appear about 5 degrees below the Moon. The Moon will reach its high point for the night at 8:23 PM, and Aldebaran will set first in the west-northwest on Sunday morning at 3:28 AM.

Sunday evening, January 24, 2021, will be when the planet Mercury will appear at its highest above the horizon (5 degrees) at the time evening twilight ends (at 6:22 PM EST).

Sometime in the second half of January to early February, 2021 (2021-Jan-25 10:28 UTC with 7 days, 22 hours, 6 minutes uncertainty), Near Earth Object (2018 BA3), between 15 and 33 meters (48 to 107 feet) across, will pass the Earth at between 0.7 and 9.2 lunar distances (nominally 1.5), traveling at 8.08 kilometers per second (18,080 miles per hour).

On Tuesday evening into Wednesday morning, January 26 to 27, 2021, the bright star Pollux will appear near the waxing gibbous Moon. As evening twilight ends (at 6:24 PM EST), Pollux will appear about 9 degrees to the lower left of the Moon. The Moon will reach its high point for the night at 10:59 PM with Pollux about 8 degrees to the upper left. By the time morning twilight begins Wednesday morning at 6:18 AM, Pollux will appear about 6 degrees above the Moon, which will only be about 23 minutes from setting in the west-northwest.

The full Moon after next will be on Thursday afternoon, January 28, 2021, appearing opposite the Sun at 2:16 PM EST.