December Skies

by Dick Cookman

November 30, 2022

Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, December Moon

Focus Constellations: Ursa Major, Ursa Minor, Draco, Cepheus, Cassiopeia, Perseus, Camelopardalis, Auriga, Gemini, Taurus, Aries, Pisces, Andromeda, Pegasus, Cygnus

Comet Journals

Comet C/2020 V2 (ZTF) is between Polaris and the tail of Draco and will pass Polaris before Christmas. It It is at 10th magnitude and should maintain that brightness until after it passes perihelion in May, 2023. It will be closest to Earth in September, 2023.

Comet C/2022 E3 (ZTF) is between Hercules and Bootes. It is currently at 10th magnitude, and will brighten in December. It is expected to reach naked eye visibility as a Christmas comet and achieve maximum brilliance when at perihelion on January 13 or when closest to Earth in early February.

Mars Landers

Why should we devote so much effort to study Mars? Most of the meteorites which bombard Earth are thought to come from the Asteroid Belt and some come from impacts on Mars which blast material into space. Mars is closer to the Asteroid Belt than Earth, indicating that bombardment was more thorough. Meteorites often contain abundant organic molecules including amino acids – the building blocks for proteins. In addition, some meteorites contain abundant water and carbon dioxide ice. Billions of years ago, Mars was probably the recipient of vast quantities of the above components from the nearby Asteroid Belt. Our landers and rovers have provided abundant evidence that Mars weather was much milder and that it had running water, lakes, and possibly oceans where these components may have formed the building blocks for the first life in the Solar System. Life on Earth may have even come from debris blasted off of Mars by later impactors from the Asteroid Belt!

Meteor Showers

The best December showers for the northern hemisphere are the Geminid (12/14 – 2 days before last quarter Moon) and Ursid (12/22 – waning crescent Moon). The former is one of the best showers of the year, rivaling the August Perseids. Minor showers include the Chi Orionids (12/2) and Monoceratids (12/9) which will have to contend with glare from the gibbous Moon, and Coma Berenicids (12/20) which will occur during the waning crescent Moon phase.

• December 14: Geminids. Active December 7 – 17, Radiant 7h28m +33°, ZHR 120, 35km/sec. Waning gibbous Moon. Progenitor: possibly minor planet 3200 Phaethon
• December 22: Ursids. Active December 17 – 26, Radiant 14h28m +76°, ZHR variable, up to 50, 33km/sec. Waning crescent Moon. Progenitor: Comet 8P/Tuttle.

Planet Plottings

All the planets are in the evening sky in December when Mercury (-0.5 to +1.2), Venus (-3.8), and the Sun all move through Ophiuchus and Sagittarius together. Early in the month, Mercury and Venus set about a half hour after the Sun and move higher in the western sky and set later each evening throughout the month. Mercury is at greatest eastern elongation (20°) on the 21st and is 1.4° from Venus on the 29th. A very thin waning crescent Moon passes both on the 24th.

Saturn (+0.8) is in the south-southwest in Capricornus. It sets 4 hours after Venus on the 1st. The waxing crescent Moon and Saturn set slightly less than 2 hours after Venus on the 26th. Neptune (+7.9) in Aquarius and Jupiter (-2.4 to -2.2) in Pisces are in the southwest evening sky in December and set with the waxing gibbous Moon about an hour after Midnight EST on the 1st. They set with the waxing crescent Moon an hour before Midnight on the 31st. Uranus (+5.6 to +5.7) and Mars (-1.8 to -1.2) rise in the late afternoon in Aries and Taurus on the 1st, respectively and set during dawn. On the 31st, they rise in the mid-afternoon and set after everyone is in bed. They can be found near the waxing gibbous Moon on the 5th and 8th respectively. Mars (-1.3 to -1.8) is at one of its best oppositions in years on December 1st, appearing higher above the horizon than it was during recent oppositions. After sunset, the bright reddish orange planet dominates the eastern and southeastern sky and joins brilliant Jupiter in the south.

December Moon

The New Moon of December in Sagittarius on the 23rd at 5:17AM EST follows the northern Winter Solstice which is at 4:48PM EST on December 21st (mid-summer in the southern hemisphere). The New Moon is the start of Lunation 1237 which ends 29.65 days later with January’s New Moon in Capricornus on the 21st at 8:53PM EST. The Full Moon is in Taurus on the 7th at 11:08PM EST. The December Moon is the “Moon before Yule.” It was called the “Oak Moon” in Medieval England and for Celts it was the “Cold Moon”. In China, it is the “Bitter Moon” and Colonial Americans called it “Christmas Moon”. Anishnaabe (Odawa and Ojibwe) first people recognize the 12th Moon as “Manidoo-Giizisoons” (Little Spirit Moon). Earth Haven Farm in Ontario documents the cultural teaching which explains the cycle of life and nature of the 12th Grandmother Moon of Creation as follows: “The twelfth moon of Creation is the Little Spirit Moon, a time of healing. By receiving both vision of the spirits and good health, we may walk the Red Road with purest intentions, and we can share this most positive energy with our families and friends for the good of all.”

Lunar Apogee (maximum lunar distance) in December is on the 11th at 7:28PM EST, when the Moon will be at a distance of 252,195 mi. (63.64 Earth radii). Lunar Perigee distance (minimum lunar distance) is 222,619 mi. (56.17 Earth radiil) on the 24th at 3:27AM EST. The waxing gibbous Moon appears to pass Neptune and Jupiter on the 1st, Uranus on the 5th and brilliant Mars on the 7th. The waxing crescent Moon passes Venus and Mercury on the 24th, Saturn on the 26th and Neptune on the 28th. On the 29th, it passes Jupiter.