Archive for month: January, 2021

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

Focus Constellations:  Ursa Major, Ursa Minor, Draco, Cepheus, Camelopardalis, Cassiopeia, Andromeda, Pisces, Perseus, Auriga, Taurus, Orion, Gemini, Cancer

Comet Journals

Comet  88P/Howell (2020) is at 11th magnitude in Aquarius. It was closest to the Sun when it passed through perihelion in September 2020 and is rapidly dimming as it retreats to its outer asteroid belt aphelion. 

Comet C/2020 M3 (ATLAS) is at 10th magnitude in Auriga. It passed through perihelion between the orbits of Earth and Mars in October and is dimming as it retreats to its aphelion beyond the orbit of Neptune. 

Mars Landers

Between 3 or 4 billion years ago, the surfaces of Mars and Earth were warm, wet, and shrouded in thick atmospheres. That was before Mars changed. NASA is investigating how that happened with the InSight (short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) Lander which is studying the composition of the interior of Mars, how that material is layered, and how quickly heat seeps to the surface. This information may have implications about the likelihood of past or current life on Mars. After months of drilling attempts frustrated by the Martian “duracrust,” Insights’ heat probe is finally buried and drilling deeper into the Martian surface. It is targeting a depth where it can obtain temperature data revealing the temperature gradient and rate of heat loss of the planet. The lander’s seismometer recorded 100s of small “Mars quakes” from April through June of 2020. They revealed that Mars has internal layering with a core that may be liquid and a crust thinner than that of Earth. Although the seismometer recorded abundant deep seated S and P seismic waves during the interval of seismic activity, there was a puzzling lack of surface seismic waves followed by a more puzzling cessation of quakes, possibly due to highly fractured rock layers which absorbed and subdued the waves or caused by masking of the seismic waves by winds. In any case, the puzzles indicate that much more investigation is necessary.

After collection of multiple drilling samples from the Mary Anning clay rich rock outcrop on Mt. Sharp in Gale Crater in late October, Curiosity resumed its ascent of the mountain and spent most of November and December climbing stair-steps composed of a series of almost horizontal rock layers. No drilling was attempted, but the layers were examined in detail with onboard cameras. Sedimentary structures such as cross bedding, ripple marks, and other bed-forms yielded abundant evidence that the sediments from which the layers were formed were deposited by currents of water or wind. The stairs rose to a dune field which permitted further observation of the nature of Martian eolian activity. The target of the current trek is the distant “sulfate unit” first observed by orbiting satellites.

Meteor Showers

January hosts 2 meteor showers for Northern Skies. The Quadrantids are the best unless January clouds or the Gibbous Moon intervenes. The Delta Cancrids, are a minor shower without competition from a Crescent Moon.

January 3: Quadrantids. Active Jan 1-Jan 5. Radiant 15h20m +49°, ZHR 120. 41km/sec. Waning Gibbous Moon. Progenitors: Asteroid (196256) 2003 EH1.
January 17: Delta Cancrids. Active Jan 1-Jan 24, Radiant 8h40m +20°, ZHR 4 variable, 28 km/sec. Waxing Crescent Moon. Progenitor: Asteroid 3200 Phaethon.

Planet Plotting 

January evening skies are replete with bright stars and planets. Jupiter, Saturn, and Mercury set after the Sun in the southwestern sky, and in the Southeast, look for the rising “Great Circle” of bright, first magnitude stars. Starting with Sirius (the brightest at -1.46 magnitude) in Canis Major, the circle continues clockwise with Procyon (+0.4) in Canis Minor, Pollux (+1.1) and Castor (+1.6) in Gemini, Capella (+0.1) in Auriga, Aldebaran (+0.9) in Taurus, and Rigel (+0.1) in Orion. Betelgeuse (+0.5) in Orion appears close to the center of the circle.

Jupiter (-1.8) & Saturn (+0.6) move from the evening sky to the morning sky in January as Saturn passes conjunction with the Sun on the 23rd and Jupiter follows on the 28th. After sunset on January 10, Saturn, Mercury, and Jupiter will appear within a circle with a diameter of less than 2.5° in Capricornus about 12° from the Sun.

Mercury (-0.9) and Venus (-3.8) remain evening and morning stars respectively all month. Mercury climbs out of sunset’s glow during the 1st three weeks of the month, reaching maximum eastern elongation on the 23rd when it is 18.6° from the Sun. Mercury’s closest approach to Saturn is at midnight on the 10th, and it is close to Jupiter at 2:00PM EST on the 11th. Neptune (+7.9) in Aquarius is an evening planet in the southwestern sky after sunset.

Planet	Constellation(s)	Magnitude	Planet Passages	Time	Date
Sun	Sagittarius, Capricornus	-26.8	New Moon	Midnight EST	1/13
Mercury	Sagittarius, Capricornus	-0.9 to -0.8	Saturn, 1.61°NNW Jupiter, 1.41°NNW Max. East Elongation	Midnight, EST 2:00PM EST   9:00PM EST	1/10          1/11          1/23
Venus	Ophiuchus, Sagittarius	-3.8
Mars	Pisces, Aries	-0.2 to +0.4	Uranus, 1.62°SSE	3:00PM EST	1/20
Jupiter	Sagittarius, Capricornus	-1.8	Mercury, 1.41°SSE   Solar Conjunction	Midnight, EST   9:00PM EST	1/10  1/28
Saturn	Sagittarius, Capricornus	0.6	Mercury, 1.61°SSE   Solar Conjunction	2:00PM EST 10:00PM EST	1/11 1/23
Uranus	Aries	+5.7 to +5.8	Mars, 1.62°NNW	3:00PM EST	1/20
Neptune	Aquarius	+7.9

Mars and Uranus have their own close encounter on the 20th when Mars (+0.2) appears within less than 2° from Uranus (+5.8) in Aries. Venus will slowly drop deeper into the glow of sunrise during January and February. It reaches solar conjunction in late March after which it moves into the evening sky.

Even though the December Solstice is the shortest day of the year, latest sunrise occurs on January 4 at 40°N and earliest sunset is on December 7. This is because the length of the solar day is not always 24 hours. Two factors that change the length of the solar day are (1) that the earth’s orbit is an ellipse which causes Earth to orbit faster when close to the Sun in northern hemisphere winter and slower when farthest from the Sun in summer and (2) Earth’s axis is tilted with respect to its orbit, producing variation of solar day period at different latitudes and dates.

The waning crescent Moon is within 1.5° of Venus at 4:00PM EST on the 11th and 1.0° from Mercury at 5:00AM EST on the 14th. The waxing crescent Moon is 3.2° from Saturn at 6:00PM EST and 3.3° from Jupiter at 6:00PM and 10:00PM EST respectively, on the 13th. It is 4.1° from Neptune at 5:00AM EST on the 17th. The waxing gibbous Moon is 3.1° from Uranus at 5:00AM EST on the 19th, and 4.7° from Mars at 6:00AM EST on the 21st.

January Moon 

New Moon on January 13 at Midnight EST is the start of Lunation 1213 which ends 29.58 days later with the New Moon of February on the 13th at 2:07PM EST. The Full Moon of January is on the 28th at 2:17PM EST. It is commonly known as the “Moon after Yule” or “Old” Moon. In colonial times, the January Moon was the “Winter Moon”. In Medieval England, the it was the “Wolf Moon.” The Chinese call it the “Holiday Moon” and Celts named it the “Quiet Moon” because January was the month to stay close to the hearth at home during the cold, quiet hours of darkness. It was associated with Brighid, the Celtic Fire goddess of hearth and home. Anishinaabe (Odawa and Ojibwe) people recognize it as “Manidoo-Giizis” (Great Spirit Moon).

At Lunar Perigee, on the 9th at 10:47AM EST, the Moon is 228,283 miles from Earth (57.60 Earth radii). Apogee (maximum solar distance), on January 21 at 8:00AM EST, the Moon is 251,267 miles (63.40 Earth radii).

Planet	Constellation	Magnitude	Moon Passages	Moon Phase	Moon Age
Sun	Ophiuchus	-26.8	Midnight EST, 1/13	New	0 days
Mercury	Ophiuchus	-1.0	2.28°SE, 5:00AM EST, 1/14	Waning Crescent	1.20 days
Venus	Libra	-3.8	1.5°S, 4:00PM EST, 1/11	Waning Crescent	28.20 days
Mars	Pisces	-0.5	4.7°SE, 6:00AM EST, 1/21	Waxing Gibbous	8.25 days
Jupiter	Sagittarius	-1.8	3.3°SE, 10:00PM EST. 1/13	Waxing Crescent	0.92 days
Saturn	Capricornus	0.6	3.2°SE, 6:00PM EST, 1/13	Waxing Crescent	0.75 days
Uranus	Aries	5.7	3.1°SE, 5:00AM EST, 1/19	Waxing Gibbous	6.20 days
Neptune	Aquarius	7.9	4.1°SE, 5:00AM EST, 1/17	Waxing Crescent	4.20 days