The Skies of October 2020 by Dick Cookman

The Skies of October 2020

Written by Dick Cookman

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

Focus Constellations:  Ursa Major, Ursa Minor, Draco, Hercules, Lyra, Cygnus, Aquila, Pegasus, Andromeda, Cepheus, Cassiopeia, Perseus, Camelopardalis

Comet Journals

Comet  88P/Howell (2020) is in Scorpius and will move into Sagittarius in late October. It is at 8th magnitude and passed through perihelion in Scorpius on September 26th. It is a short period comet with an aphelion slightly inside the orbit of Jupiter and a perihelion inside the orbit of Mars. 

Comet C/2020 P1 (NEOWISE) is another Neowise comet discovered in August. It is in southern hemisphere skies in Centaurus and will move through Hydra and into Virgo by mid – October. It is below the plane of the solar system and will pass through it between Earth and the orbit of Mercury at perihelion on October 20 when it will reach 9th magnitude. It is a long period comet from the Oort Belt.

Comet C/2020 M3 (ATLAS), at 10th magnitude in southern hemisphere skies in Eridanus, will reach perihelion on October 25 and will move into northern skies in November when it may reach 9th magnitude when it is closest to Earth on November 14. 

Mars Landers

Since landing on Mars in November 2018 the InSight probe has measured weather conditions, detected Marsquakes, determined depths to the boundaries between the internal layering of Mars and collected preliminary information about the composition of the deep layers. It has had difficulties drilling through the unusually thick “duracrust” to position its heat probe at a desired depth between 10 and 16 feet below ground level where internal heat can be measured. After months of unsuccessful drilling, mission scientists developed techniques which allowed limited success in June and July. On August 28, NASA reported “another short test has my self-hammering mole making gradual progress. Pressing down on the (surrounding) soil above has helped it dig a little further. We’ll do another of these moves soon with NASAJPL and @DLR_en keeping a close eye.” 

For the last five years, Curiosity has analyzed samples of Martian air in Gale Crater with its Sample Analysis at Mars (SAM) chemistry lab to determine seasonal changes. The air is 95% carbon dioxide with nitrogen, argon, oxygen, and carbon monoxide comprising most of the remaining 5%. In the winter, carbon dioxide freezes at the polar caps and decreases atmospheric pressure. Nitrogen and argon percentages rise in winter and decrease in summer when polar carbon dioxide ice melts and atmospheric carbon dioxide increases. Oxygen and small amounts of methane behave in a more puzzling manner. They both spike in the summer for reasons not currently understood. The puzzle is further complicated because oxygen and methane levels don’t always rise and fall together.

On Earth, oxygen and methane levels vary mostly due to life activity, but life is everywhere and overwhelms changes due to strictly physical/chemical processes unrelated to life. Can the changes on Mars be explained by such physical/chemical activity? Scientists have not yet developed viable explanations for this. The jury is still out, leaving a tantalizing opening for creative biological explanations.

Meteor Showers

The best meteor showers in October are the Orionids unless the Draconids storm. 

October 8 & 9: Draconids. Active October 6-October 10. Radiant 17h28m +54°, ZHR 0 to storm. 20 km/sec. Waning Gibbous Moon. Progenitor: Comet 21P/Giacobini-Zinner.

October 18: Epsilon Geminids. Active October 14-October 27, Radiant 6h48m +27°, ZHR 2, 70 km/sec. Waxing Crescent Moon. Progenitor: Comet C/1964 N1 (Ikeya). 

October 21: Orionids. Active October 2-November 7, Radiant 06h20m +16°, ZHR 20, 66 km/sec. Waxing Crescent Moon. Progenitor: Comet 1P/Halley.

Planet Plotting 

A brilliant morning star, Venus (-4.0 to -3.9) in Leo and Virgo, dims slightly in October as it orbits away from Earth and toward the Sun’s other side. It rises about 4:00AM EDT near Regulus in Leo. Uranus (+5.7) in Aries doesn’t set until after dawn during most of the month. It is in the western predawn sky while Venus dominates the eastern sky. The frequently mispronounced planet (use your Latin vowel pronunciation) is best viewed when at Opposition on the 31st. 

Mars (-2.5 to -2.6 to -2.2) in Pisces also sets after dawn but is also visible in the latter part of the evening before Opposition on the 13th when Mars and the Sun are on opposite sides of Earth. Mars takes twice as long as Earth to orbit the Sun so we only get to see it up close every two years. The red planet is unusually close during the 2020 opposition and will not again be this close (38+ million miles) until 2035. It was slightly closer in 2018 but was not as high in the sky as it will be this year when it is well above the horizon where views of celestial objects are distorted by dense, turbulent air near Earth’s surface. Mars is currently brighter than any other planet except Venus and the two are best compared when on opposite sides of the predawn sky. Mars will be slightly brighter on the 6th than during Opposition on the 13th because it will be nearer to Earth. 2020 and 2018 are the best years to view Mars in the interval between 2003 to 2035. Mars will start dimming after its Opposition, but viewing will remain favorable into November as Mars moves higher in the sky early in the evening.

Planet	Constellation(s)	Magnitude	Planet Passages	Time	Date
Sun	Virgo	-26.8	New Moon	3:31PM EDT	10/16
Mercury	Virgo	+0.1 to +1.7	Max East Elongation          Inferior Conjunction	Noon, EDT 2:00PM EDT	10/1 10/25
Venus	Leo, Virgo	-4.0 to -3.9
Mars	Pisces	-2.5 to -2.6 to -2.2	Closest approach to Earth Opposition	10:00AM EDT 7:00PM EDT	10/6 10/13
Jupiter	Sagittarius	-2.2 to -2.0
Saturn	Sagittarius	+0.5 to +0.6
Uranus	Aries	+5.7	Opposition	Noon EDT	10/31
Neptune	Aquarius	+7.8

Neptune (+7.8), in Aquarius, Saturn (+0.5 to +0.6) and Jupiter (-2.2 to -2.0) in Sagittarius, and Mercury (+0.1 to +1.7) in Virgo are evening planets in October. Mercury is at maximum Eastern Elongation on the 1st but is low in the sky because its orbit is close to the horizon in the western sky in October. As it approaches Inferior Conjunction with the Sun on the 25th, it will dive deeper into the glow of sunset and disappear. Jupiter and Saturn dominate the southern evening sky and set around midnight. Neptune rises before sunset and sets well after midnight.

The waning gibbous Moon is within 0.7° of Mars at 11:00PM EDT on the 2nd, and 3.0° from Uranus at 5:00AM EDT on the 4th. The waning crescent Moon is 4.0° from Venus at 8:00AM EDT on the 13th and the waxing crescent Moon is 7.0° from Mercury on the 17th.  On the 22nd, the waxing crescent Moon is 3.0° from Saturn at Midnight EDT and 2.0° from Jupiter at 5:00AM EDT. The waxing Gibbous Moon is 4.0° from Neptune at 2:00AM EDT on October 27, 3.0° from Mars on the 29th, and 3.0° from Uranus on the 31st.

October Moon 

The New Moon on October 16 at 3:31PM EDT is the beginning of Lunation 1210 which ends 29.35 days later with the New Moon on November 15 at 12:07AM EDT. The Full Moon of October is at 5:05PM EDT on the 1st. It is commonly known as the “Hunters” Moon, but is the “Harvest Moon” this year because it is the full moon closest to the Autumnal Equinox which was on September 22nd. A 2nd Full Moon occurs on the 31st at 10:49AM EDT. According to the 1946 Sky and Telescope definition as the 2nd full moon in a month, it is a blue moon. Since it is on the 31st, it is an extremely rare “Halloween Blue Moon”! In colonial times, the “Harvest Moon” was in October. In Medieval England, the October full moon was the “Blood Moon.” Celts named it the “Harvest Moon” and the Chinese call it the “Kindly Moon”. Anishinaabe (Odawa and Ojibwe) people recognize it as “Binaakwe-giizis” (Falling Leaves Moon). 

Lunar Apogee (maximum orbital distance) is on October 3 at 1:22PM EDT when the Moon’s distance is 252,476 miles (63.70 Earth radii). Perigee is on the 16th at 7:46PM EDT when the Moon is 221,775 miles from Earth (55.96 Earth radii).

Planet	Constellation	Magnitude	Moon Passages	Moon Phase	Moon Age
Sun	Virgo	-26.8	3:31PM EDT, 10/16	New	0 days
Mercury	Libra	1.5	7.0°N, 3:00PM EDT, 10/17	Waxing Crescent	1.33 days
Venus	Leo	-3.9	4.0°N, 8:00PM EDT, 10/13	Waning Crescent	26.54 days
Mars	Pisces	-2.5 -2.2	0.7°S, 11:00PM EDT, 10/2 3.0°S, Noon EDT, 10/29	Waning Gibbous Waning Gibbous	15.42 days      12.72 days
Jupiter	Sagittarius	-2.1	2.0°S, 1:00PM EDT. 10/22	Waxing Crescent	6.25 days
Saturn	Sagittarius	0.6	3.0°S, Midnight EDT, 10/22	Waxing Crescent	5.71 days
Uranus	Aries	5.7	3.0°S, 5:00AM EDT, 10/4 3.0°S, 9:00AM EDT, 10/31	Waning Gibbous Waxing Gibbous	16.92 days      15.08 days
Neptune	Aquarius	7.8	4.0°S, 2:00AM EDT, 10/27	Waxing Gibbous	10.79 days