moon rising over rocky ridge
The waxing November Moon rises over a ridge in the Wasatch Mountains, Utah. Credit: NASA/Bill Dunford

The next full Moon will be just after midnight on Friday morning, November 23, 2018, appearing "opposite" the Sun (in Earth-based longitude) at 12:39 AM EST. The Moon will appear full for about three days centered around this time, from Wednesday night through Saturday morning.

As the last full Moon of Autumn, this Moon is known as the Frost Moon or the Moon Before Yule. The Maine Farmer's Almanac first published Native American names for the full Moons in the 1930's, and according to this almanac, the tribes of what is now the northern and eastern United States named this full Moon the Frost Moon, as frosts began to occur at the end of Fall. Europeans 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.

Many writers tie these Moon names to the European months, so that the full Moon in November is the Beaver Moon, regardless of whether it is the last moon of Fall or the first moon of Winter. Most of the time the names by European month correspond with the names by season, but right now they are out of sync, and will remain so until the Spring of 2019, when we will have a season with four full Moons.

This full Moon is Kartik Purnima, celebrated by Hindus, Jains, and Sihks (each for different reasons). In Laos, this is the That Luang Festival, a celebration centered around the oldest and most highly acclaimed of all Buddhist temples in Laos. In Sri Lanka, this is the Ill (or Il) Poya (or Full Moon), commemorating the Buddha's ordination of sixty disciples as the first missionaries.

In lunisolar calendars the months change with the new Moon and full Moons fall in the middle of the lunar month. This full Moon falls near the middle of the tenth month in the Chinese calendar and Kislev in the Hebrew calendar. Hanukkah begins on the 25th of Kislev (corresponding this year to sundown on Sunday, December 2, 2018). 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-Awwal, the third month of the Islamic year.

For the Washington, DC area, on the day of the full Moon on Friday, November 23, 2018, morning twilight will begin at 5:58 AM, sunrise will be at 7:00 AM, the Sun will reach a maximum altitude of 30.7 degrees at 11:54 AM, sunset will be at 4:49 PM, and evening twilight will end at 5:51 PM EST. The length of a day (as measured for example from noon to noon on a sundial) varies through the year. Around the solstices, the length of a solar day is slightly longer than the 24 hour average. The day of the northern hemisphere winter solstice has the shortest period of daylight for the year, but is one of the longest solar days of the year. 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, the earliest sunsets will occur on the 12 days from Saturday, December 1, 2018, through Wednesday, December 12, 2018 (rounded to the minute, sunset will be at 4:46 PM EST across these dates). As a bicycle commuter, I notice when the Sun sets this early. Be sure to check your lights before your ride. By the day of the full Moon on Saturday, December 22, 2018, morning twilight will begin at 6:20 AM, sunrise will be at 7:24 AM, the Sun will reach a maximum altitude of 27.7 degrees at 12:07 AM, sunset will be at 4:50 PM, and evening twilight will end at 5:53 PM EST.

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

Mark Your Calendars

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

There are two special sky watching events coming up during this lunar month, the annual Geminid meteor shower and the close approach of comet 46P/Wirtanen.

One of the best meteor showers of the year, the annual Geminid meteor shower will be active from about December 4 to about December 17, peaking late Thursday night, December 13 into early Friday morning, December 14, 2018. The best time to look will be after midnight but before the sky begins to show any trace of dawn, when the part of the Earth you are on is headed into the stream of meteorites and the Moon will have already set. For the best viewing, you need to be far away from artificial light, with a clear view of the sky, and no haze or clouds in the sky. It can take your eyes 30 minutes or so to completely adapt to the dark, so no checking your smart phone between meteor watches. See https://leonid.arc.nasa.gov/estimator.html to develop an estimate for your area and viewing conditions. At its peak, if you have ideal conditions, a very clear sky far away from city lights, you should be able to see over 100 meteors per hour. Even from the darker suburbs of Washington DC, after midnight but before the sky starts to show any sign of dawn, you should be able to see 30 to 40 meteors per hour.

The Geminids get their name from Gemini, as they appear to radiate out from this constellation. The Geminids are relatively slow moving as they hit the Earth (at 78,000 miles per hour). The Geminids appear to be one of only two annual meteor showers associated with asteroids rather than comets (sometimes called rock comets). The Geminids appear to be dust associated with the asteroid 3200 Phaethon, which has an eccentric 1.4 year-long 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 where all the dust that causes these meteors has come from. One possibility is that this asteroid may have shot out gas and dust when it was close to the Sun in past orbits. There are other possible explanations for where the dust that causes the Geminids came from (and thanks to Bill Cooke at NASA MSFC for this information). There is another asteroid 2005 UD, that appears to be in a related orbit. It is possible that two asteroids collided with one another, producing 2005 UD, 3200 Phaethon, and the massive amounts of debris that cause the Geminids each year, or that a larger body in a similar orbit broke apart due to thermal stress, producing these two asteroids and the Geminids stream.

Although December 14 is the expected peak, the Geminids are active from December 4th through December 17th, so if you are out after 10 pm during this time and the sky is clear and dark, you just might see a shooting star.

Also in mid-December, the comet 46P/Wirtanen will pass about 30 lunar distances from the Earth, close enough to be visible with a telescope or binoculars (and possibly to the naked eye under ideal viewing conditions). Although the orbit of this comet is well known, it is hard to predict how bright a comet will appear. As the astronomer David H. Levy says, "Comets are like cats; they have tails, and they do precisely what they want." This comet makes its closest approach on Sunday morning, December 16, 2018. Rather than try to describe how this comet will appear to move across the sky for the nights around this closest approach, I suggest you search for visual guides on the web, which can provide you with information on where to look. If you want to try to see this comet with the naked eye on the morning of the closest approach, I suggest looking on Sunday morning, December 16, 2018, after moonset, when the comet will appear in the west-southwest about 55 degrees above the horizon.

As Autumn ends and Winter begins, the daily periods of sunlight are short, with the shortest on the day of the northern hemisphere winter solstice. For the Washington, DC area, on the day of the full Moon on Friday, November 23, 2018, morning twilight will begin at 5:58 AM, sunrise will be at 7:00 AM, the Sun will reach a maximum altitude of 30.7 degrees at 11:54 AM, sunset will be at 4:49 PM, and evening twilight will end at 5:51 PM EST. As mentioned above, the earliest sunsets of the year will occur on the 12 days from Saturday, December 1, 2018, through Wednesday, December 12, 2018. By the day of the full Moon on Saturday, December 22, 2018, morning twilight will begin at 6:20 AM, sunrise will be at 7:24 AM, the Sun will reach a maximum altitude of 27.7 degrees at 12:07 AM, sunset will be at 4:50 PM, and evening twilight will end at 5:53 PM EST.

On the evening of the November full Moon, as evening twilight ends, the planet Mars is the brightest planet visible, appearing in the south about 40 degrees above the horizon. Saturn will appear in the southwest about 12 degrees above the horizon. Uranus and Neptune are also in the sky, but too dim to see without a telescope. The trio of bright stars called the "Summer Triangle" will appear high in the west. Closest to overhead will be Deneb, the brightest star in the constellation Cygnus the Swan; to the west-northwest will be Vega, the brightest star in the constellation Lyra the Harp; and to the south-southwest will be Altair, the brightest star in the constellation Aquila the Eagle. If you are lucky enough to live in an area where it is dark enough to see the Milky Way, our home galaxy will appear stretched nearly overhead from west-southwest to east-northeast. Over the coming weeks Mars will remain in the south, appearing to shift higher in the sky. Saturn will appear to shift to the west and closer to and the horizon, setting earlier. By mid-December Saturn will be setting in the west-southwest as evening twilight begins. By the evening of the full Moon in December, as evening twilight ends, the bright stars of the local arm of our home galaxy, including the constellation Orion, will be rising in the east.

On the morning of the November full Moon, as morning twilight begins, the brightest of the planets, Venus, as the Morning Star, will appear in the east-southeast about 20 degrees above the horizon, near the bright star Spica. The bright stars of the local arm of our galaxy will be setting in the west-southwest. Venus will reach its greatest brilliancy (an approximation of its greatest brightness) on November 30, 2018, appearing as a crescent planet when viewed with a telescope. As the weeks progress, Venus will appear to shift higher in the sky and more towards the southeast, reaching its highest in the sky (at the time morning twilight begins) for this apparition on Tuesday morning, December 18, 2018. Around the end of November, the planet Mercury will begin to emerge from the glow of dawn in the east-southeast (having passed between the Earth and the Sun on November 27). As a thin crescent, Mercury will be difficult to see at first. By December 3, Mercury will start appearing above the horizon at the time morning twilight begins. A few days later, the planet Jupiter, appearing brighter than Mercury, will begin to emerge from the glow of dawn in the east-southeast (having passed around the far side of the Sun on November 26). By December 13, Jupiter will begin appearing above the horizon at the time morning twilight begins. By the time of the next full Moon in early January, as morning twilight begins, the bright stars of the local arm of the galaxy will have set, and Jupiter and Mercury will appear near each other about 5 degrees above the horizon in the east-southeast.

As mentioned above, the next full Moon will be early on Friday morning, November 23, 2018, at 12:39 AM EST.

On Friday evening, November 23, 2018, the bright star Aldebaran will appear to the right of the full Moon. They will appear at their closest early in the evening (when they will be rising in the east-northeast, and will appear to separate as the night progresses into Saturday morning.

On Sunday mid-day, November 25, 2018, at 12:24 PM EST (2018-Nov-25 17:24 UTC with 2 minutes uncertainty), Near Earth Object (2018 VT7), between 7 and 16 meters (24 to 54 feet) in size, will pass the Earth at between 8.2 and 8.3 lunar distances (nominally 8.2), traveling at 2.33 kilometers per second (5,207 miles per hour).

Monday morning, November 26, 2018, will be when the planet Jupiter passes on the far side of the Sun as seen from Earth, called conjunction.

Monday morning, November 26, 2018, at 7:10 AM EDT, the Moon will be at perigee, its closest to the Earth for this orbit.

Sometime around Monday, November 26, 2018 (2018-Nov-27 00:14 UTC with 2 days, 1 hour, and 2 minutes uncertainty), Near Earth Object (2008 WD14), between 70 and 156 meters (229 to 513 feet) in size, will pass the Earth at between 3.2 and 16.2 lunar distances (nominally 7.4), traveling at 9.30 kilometers per second (20,810 miles per hour).

Tuesday morning, November 27, 2018, will be when the planet Mercury passes between the Earth and the Sun, called inferior conjunction.

Late Wednesday night, November 28, into Thursday morning, November 29, 2018, the bright star below the waning gibbous Moon will be Regulus. For the Washington, DC area, the Moon will rise at 10:41 PM, Regulus will rise at 11:03 PM, the Moon will reach its highest in the sky for the night on Thursday morning at 5:46 AM, and morning twilight will begin at 6:08 AM EST.

Thursday evening, November 29, 2018, the waning Moon will appear half-full as it reaches its last quarter at 7:19 PM EST.

On Sunday morning, December 2, 2018, at 11:03 AM EST (2018-Dec-02 16:03 UTC), Near Earth Object (2018 TG6), between 9 and 21 meters (30 to 68 feet) in size, will pass the Earth at 3.9 lunar distances, traveling at 1.36 kilometers per second (3,035 miles per hour).

Hanukkah will start at sunset on Sunday, December 2, 2018.

On Monday morning, December 3, 2018, the bright planet Venus will appear below the waning crescent Moon. For the Washington, DC area, the Moon will rise in the east at 3:09 AM, Venus will rise at 3:45 AM, and they will be bright enough to remain visible well after morning twilight begins at 6:07 AM EST.

On Wednesday morning, December 5, 2018, you might be able to catch the planet Mercury appearing below the thin, waning, crescent Moon. For the Washington, DC area, the Moon will rise in the east-southeast at 5:16 AM, Mercury will rise at 5:49 AM, and morning twilight will begin at 6:09 AM EST.

Friday, December 7, 2018, at 2:20 AM EST, will be the new Moon, when the Moon passes between the Earth and the Sun and will not be visible. In the Chinese Calendar, days begin at midnight and months begin on the day of the New Moon (in China's time zone). This New Moon marks the start of the eleventh month of the Chinese Calendar. In the Hebrew Calendar, days start at sunset and months start with the New Moon. This New Moon marks the start of Tevet.

In the Islamic calendar the months start with the first sighting of the waxing crescent Moon a few days after the New Moon. Thursday evening, December 8, 2018, will mark the beginning of Rabi' al-Thani.

On Thursday evening December 8, 2018, if you have a clear view of the horizon in the west-southwest, you might be able to see the planet Saturn appearing to the upper left of the thin, waxing crescent Moon. For the Washington, DC area, evening twilight will end at 5:49 PM, the Moon will set at 6:08 PM, and Saturn will set at 6:20 PM EST.

Sometime around Sunday, December 9, 2018 (2018-Dec-09 17:06 UTC with 2 days,8 hours, 30 minutes uncertainty), Near Earth Object (2013 VX4), between 48 and 108 meters (159 to 355 feet) in size, will pass the Earth at between 2.8 and 6.4 lunar distances (nominally 4.1), traveling at 6.62 kilometers per second (14,800 miles per hour).

On Sunday evening, December 9, 2018, at 8:54 PM EST (2018-Dec-10 01:54 UTC), Near Earth Object (2001 XG1), between 58 and 130 meters (191 to 427 feet) in size, will pass the Earth at 7.8 lunar distances, traveling at 14.20 kilometers per second (31,764 miles per hour).

Wednesday, December 12, 2018, at 7:25 AM EST, the Moon will be at apogee, its farthest from the Earth for this orbit.

As mentioned above, Friday morning, December 14, 2018, is the predicted peak of the annual Geminid meteor shower, one of the best meteor showers of the year.

On Friday evening, December 14, 2018, the bright planet Mars will appear above the waxing, nearly half-full Moon. They will appear high in the south as evening twilight ends, and will set together about 30 minutes before midnight.

On Saturday morning, December 15, 2018, the planet Mercury will be at its greatest angular separation from the Sun as seen from the Earth in the morning sky, called greatest western elongation, appearing half full when viewed by telescope.

Saturday morning, December 15, 2018, the waxing Moon will appear half-full as it reaches its first quarter at 6:49 AM EST.

On Saturday morning, December 15, 2018, at 7:00 AM EST (2018-Dec-15 12:00 UTC with 1 hour, 17 minutes uncertainty), Near Earth Object (2018 VO9), between 12 and 27 meters (40 to 89 feet) in size, will pass the Earth at between 2.6 and 2.7 lunar distances (nominally 2.6), traveling at 2.87 kilometers per second (6,428 miles per hour).

On Sunday morning, December 16, 2018, at 8:05 AM EST (2018-Dec-16 13:05 UTC), Comet 46P/Wirtanen will pass the Earth at 30.1 lunar distances, traveling at 10.07 kilometers per second (22,522 miles per hour).

On Tuesday morning, December 18, 2018, the planet Venus will reach its highest in the sky at the time morning twilight begins for this apparition.

On Thursday night, December 20, into Friday morning, December 21, 2018, the bright star appearing near the waxing gibbous Moon will be Aldebaran. As evening twilight ends, Aldebaran will appear to the lower left of the Moon. The pair will appear to shift closer to each other until they are at their closest at around 3:30 AM. For the Washington, DC area, Aldebaran will set at 5:43 AM EST.

On Friday morning, December 21, 2018, the bright planets Mercury and Jupiter will appear within a degree of each other. To see them, you will need to look around the time morning twilight begins, and have a clear view of the horizon about half-way between east-southeast and southeast. For the Washington, DC area, at the time morning twilight begins (6:20 AM EST), Jupiter, the brighter of the two (apparent magnitude of -1.6) will appear about 5 degrees above the horizon, with Mercury (apparent magnitude of -0.4) appearing to the upper left of Jupiter. Shining much brighter than either Jupiter or Mercury, the planet Venus (with a apparent magnitude of -4.4) will appear high in the southeast, about 27 degrees above the horizon. The bright star to the lower right of Mercury and Jupiter will be Antares (apparent magnitude 1.1).

I don't normally mention the apparent magnitude of celestial objects, as many find it a confusing scale. This scale traces back to Greek astronomers, who divided the visible stars into six magnitudes, with 1 being the brightest and 6 the dimmest. In the mid-1800's this was formalized by defining a star with magnitude 1 as being 100 times brighter than a star with magnitude 6. This means each decrease of 1 in magnitude corresponds to an increase of about 2.512 times in brightness. The smaller the number, the brighter the object, and the brightest planets and stars have negative apparent magnitudes.

Wednesday, December 21, 2018, at 5:22 PM EST, will be the Winter Solstice, the astronomical end of Fall and start of Winter. This is the day with the shortest period of sunlight (although it is one of the longer solar days of the year, as mentioned earlier in this Moon Missive). 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.

On Friday evening, December 21, 2018, at 8:04 PM EST (2018-Dec-22 01:04 UTC), Near Earth Object 163899 (2003 SD220), between 922 and 2,061 meters (0.57 to 1.28 miles) in size, will pass the Earth at 7.4 lunar distances, traveling at 6.24 kilometers per second (13,957 miles per hour).

The full Moon after next will be on Saturday, December 22, 2018, at 12:49 PM EST.

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