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The Skies of September, 2023

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September Skies

by Dick Cookman

September 2, 2023

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

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

Comet Journals

Comets C/2023 P1 (Nishimura) is at magnitude 6 and could possibly reach naked eye visibility at magnitude 4 or even brighter. It will be best viewed before dawn in the first week of September between Cancer and Leo. It will move through Leo in the 2nd week and Virgo in late September before dropping into southern hemisphere skies. It is a Oort Belt comet and will be closest to Earth on September 12 when it will pass through perihelion on September 18. Comet 103P/Hartley 2 is in Perseus and will be closest to Earth on September 26 and will reach perihelion on October 12. It will pass into and through Auriga in September, Gemini and Cancer in October, then circle through southern hemisphere skies as it leaves the inner solar system and travels beyond Jupiter.

Mars Landers

The Mars rovers have been gathering evidence about Mars for more than a quarter century. Scientists on Earth are flooded with data gathered over that time. They have surveyed the information that appears to be most important but are far from comprehensive examination of the tremendous amount of data gathered. It will require decades for the current number of scientists to dig through this data and more is coming in daily. We need a whole lot more scientists, a situation not restricted to planetary science! Curiosity collected evidence of preserved ancient mud cracks on June 20, 2021. Analysis was finally made and the conclusion that the surface of Gale Crater on Mars underwent high frequency wet-dry cycling was published in August of this year in Nature. Data collected by the Insight lander during its 4 year mission was examined and the conclusion that the rotation rate of Mars is slowly speeding up in its rotation rate, possibly due to climatic changes which redistribute H2O globally. The story goes on, we will be mining Mars data for years, deducing its geologic history, life potential, and hints about Earth’s future.

Meteor Showers

September hosts the moderate Alpha Aurigid meteor shower and the minor Delta Aurigids and Piscids (9/20). Neither one is very favorable due to lunar glare or relatively scarce meteors.

  • September 1, 4AM: Alpha Aurigids. Active Aug 25 – September 5. Radiant 05h36m +42°. ZHR 10. 66 km/sec. Unfavorable, Waning Gibbous Moon. Progenitor: Comet Kiess (C/1911 N1).
  • September 29, 4AM: Delta Aurigids. Active September 18 – October 10. Radiant 04h00m +47°. ZHR 6. 64 km/sec. Unfavorable – Full Moon glare. Progenitor: Comet Keiss.

Planet Plottings

Mercury (4.9 to -0.9) in Leo, Venus (-4.3 to -4.4) in Cancer and Leo, and Uranus (+5.8) and Jupiter (-2.5 to -2.6) in Aries are morning planets. In mid September, after its inferior conjunction with the Sun on the 6th, Mercury appears right above the eastern horizon below Regulus in Leo before sunrise. During the next week it moves higher in the sky until reaching greatest western elongation from the Sun (17.9°) on the 22nd, when Mercury presents its best morning apparition of 2023 slightly less than 18 hours before the Autumn Equinox at 2:50AM EDT on the 23rd, Venus shines brightly before dawn above Regulus throughout the month. It is brightest at -4.8 on the 9th. Uranus and Jupiter rise in Aries about 10PM EDT and are best viewed when they are high in the southern sky before dawn. Neptune rises at sunset and sets at sunrise on the19th when it reaches Opposition with the Sun Saturn is low in the eastern sky after sunset and is best viewed when it is high in the southern sky around midnight. It was brightest when at Opposition on August 27, and presents its most stunning apparition in early September. Mars is hard to find low in the western sky in the early evening and rapidly drops into the glow of sunset.

A waning gibbous Moon appears to pass Neptune on the 1st, Jupiter on the 4th, and Uranus on the 5th. The waning crescent passes Venus on the 11th and Mercury on the 13. The waxing Crescent passes Mars on the 16th, then the waxing gibbous Moon passes Saturn on the 26th and Neptune on the 28th.

PlanetConstellation(s)MagnitudePlanet PassagesTimeDate
SunLeo, Virgo-26.5New Moon9:40PM EDT9/14
MercuryLeo4.9Inferior Conjunction7:00AM EDT9/6
MercuryLeo-0.3Max. West Elongation9:00AM EDT9/22
VenusCancer, Leo-4.3 to -4.8 to -4.4   
MarsLeo, Virgo1.8 to 1.7   
JupiterAries-2.5 to -2.6   
SaturnAquarius+0.4 to +0.6   
NeptunePisces7.8Opposition7:00AM EDT9/19

September Moon

September’s New Moon is at the boundary of Leo and Virgo on the 14th at 9:40PM EDT. The New Moon marks the start of Lunation 1246 which ends 29.58 days later with the New Moon of October in Aquarius on the 14th at 1:55PM EDT. The Full Moon in September is a “Supermoon” which occurs 32 hours 59 minutes after lunar perigee (when the Moon is closest to Earth in its orbit and appears unusually large). The Full Moon on the 29th occurs at 5:58AM in Pisces. It is called the Fruit Moon. It occurs nearer to the Sept. 23rd Autumnal Equinox than its October successor, so it is defined as the “Harvest Moon”. It was called the “Barley Moon” in Medieval England and for Celts it was the “Singing Moon”. In China, it is the “Chrysanthemum Moon” and Colonial Americans called it “Harvest Moon” due to the low angle the rising Moon makes with the horizon, lighting up the farmers fields for a harvesting well into the evening. Anishnaabe (Odawa and Ojibwe) first people recognize the 9th Moon of the year as “Waatebagaa-giizis” (Leaves Turning Moon). Ontario’s Earth Haven Farm presents cultural teachings explaining the cycle of life and nature of September’s Grandmother Moon of Creation: “The ninth moon of Creation is the Corn Moon, during which time we learn about the cycle of life. Each cob of corn has thirteen rows of multicoloured seeds which represent all the spirits waiting to begin their Earth Walk. These will be the future generations for whom we must prepare.”

Lunar Apogee (max. lunar distance) is on September 12 at 11:43AM EDT. The Moon’s distance is 252,457 mi. (63.70 Earth radii). Perigee is on the 27th at 8:59PM EDT. The Moon is at 223,639 mi. (56.43 Earth radii).

PlanetConstellationMagnitudeMoon PassagesMoon PhaseMoon Age
SunLeo, Virgo-26.59:40PM EDT, 9/14New0 Days
MercuryLeo1.95.4°N, 8:00PM EDT, 9/13Waning Crescent28.6 Days
VenusCancer-4.411.0°N, 9:00AM EDT, 9/11Waning Crescent26.14 Days
MarsVirgo1.70.7°N, 3:00PM EDT, 9/16Waxing Crescent1.72 Days
JupiterAries-2.53.0°N, 4:00PM EDT, 9/4Waning Gibbous19.43 Days
SaturnAquarius0.53.0°S, 9:00PM EDT, 9/26Waxing Gibbous11.97 Days
UranusAries5.83.0°N, 9:00PM EDT, 9/5Waning Gibbous20.64 Days
NeptunePisces7.81.4° S, 3:00AM EDT, 9/1Waning Gibbous15.89 Days
NeptunePisces7.81.4° S, 1:00PM EDT, 9/28Waxing Gibbous13.64 Days

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