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The Skies of September, 2021


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September Skies

by Dick Cookman

September 5, 2021


Highlights: Comet Journals, Martian Landers, Meteor Showers, Autumnal Equinox, Planet Plotting, September Moon

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

Comet Journals

Comet 67P/Churyumov-Gerasimenko (2021) is about 10th magnitude and will be closest to Earth on November 12. It will reach perihelion on November 3 and moves from Cetus to Taurus in September. Comet 4P/Faye moves from Taurus to Orion at 10th magnitude in September. Faye is closest to the Sun at perihelion on September 8 and closest to Earth in December. Comet 6P/d’Arrest (2021) moves from Ophiuchus to Sagittarius in September. It was discovered on December, 2020 and may reach 10th magnitude when near its September 17 perihelion.

Mars Landers

On August 6, the Perseverance Rover made its first attempt to drill and extract a rock core from the floor of Jezero Crater which is thought to be an ancient lakebed. Upon extraction, the core disintegrated, breaking into irretrievable fragments. The rover was then directed to move 1,493 feet (455 meters) to a ridge nicknamed Citadelle which appeared to be more cohesive. Data received late Sept. 1, 2021 from Perseverance indicate the team has achieved its goal of successfully coring a Mars rock. The initial images downlinked after the historic event show an intact sample present in the tube after coring. More images are required to confirm.

The InSight Lander is generating daily atmospheric and opacity pressure reports. Other functions have been temporarily shut down to conserve energy limited by solar panel dust accumulation. Spacecraft orbiting Mars show that Curiosity is climbing Mt. Sharp, between a region enriched in clay minerals deposited in an ancient fresh water lake, and one dominated by salty minerals called sulfates which may be replacement minerals from salty brines which altered pre-existing clay minerals. The mountain’s layers in this area may reveal how the ancient environment within Gale Crater dried up over time.

Autumnal Equinox

The Equinox is at 3:22PM EDT on September 22, 19 hours after Full Moon. The noon Sun is directly above Earth’s equator, and a line between Earth and the Sun is at right angles to Earth’s axis, marking the transition from Summer to Autumn. Each hemisphere receives equal amounts of sunlight causing day and night to be of equal length over the entire Earth on the Equinox.

Meteor Showers

September Meteor showers include the Alpha Aurigids, Delta Aurigids, Epsilon Perseids and the Piscids. All are minor showers that will produce less than 10 meteors per hour in dark skies unpolluted by stray light.

  • September 1: Alpha Aurigids. Active Aug. 28-Sep. 5. Radiant 5h36m +42°. ZHR 10. 66 km/sec. Waning Crescent Moon. Progenitor: Comet Keiss.
  • September 8: Delta Aurigids. Active Sep. 5-Oct 10. Radiant 4h00m +47°. ZHR 6. 64 km/sec. Waxing Crescent Moon. Progenitor: Comet Keiss.
  • September 9: Epsilon Perseids. Active Sep. 5-Sep. 21. Radiant 3h12m +40°. ZHR 5. 64 km/sec. Waxing Crescent Moon. Progenitor: unknown long period comet
  • September 20: Piscids. Active Sep. 3-Oct. 2. Radiant 0h20m -01°. ZHR 3. 36 km/sec. Full Moon. Progenitor: possibly Comet Wirtanen.

Planet Plotting

Neptune (+7.8) (Opposition 9/14) rises well before midnight in Aquarius and Uranus (+5.7) in Aries rises slightly later. Both are morning planets in September. Mars (+1.8 to +1.7), in Leo and Virgo, is buried in the Sun’s glow as it approaches Superior Conjunction with the Sun in early October.

Venus (-3.9 to -4.1) and Mercury (+0.0 to +1.6) in Virgo are low in the western-southwestern sky after sunset in September. Mercury is buried in the glow of sunset on the 1st and is slightly higher in the sky each evening until it reaches Maximum Eastern Elongation from the Sun on the 14th. Venus (-3.9 to -4.1) grows brighter each evening and moves into Libra on the 18th. Both planets are low in the evening sky because even though they appear to move away from the Sun in the 1st half of the month, their movement along the ecliptic is only slightly above the horizon. Jupiter (-2.7 to -2.6) and Saturn (+0.3 to +0.53) in Capricornus rise in the eastern sky before sunset and are best viewed around 10PM EDT when they are highest in the southern sky. They set in the wee hours.

In September, the waxing crescent Moon will appear to pass the evening planets, Mercury, Mars, and Venus from the 7th through the10th. The waxing gibbous Moon will appear to pass the morning planets Saturn, Jupiter, and Neptune from the 17th through the 20th. The waning gibbous Moon will pass Uranus on the 28th.

PlanetConstellation(s)MagnitudePlanet PassagesTimeDate
SunLeo, Virgo-26.5New Moon8:51PM EDT9/6
MercuryVirgo0.0 to.1.6Maximum East ElongationMidnight EDT9/14
VenusVirgo,Libra-3.9 to -4.1   
MarsLeo,Virgo1.8 to 1.7   
JupiterCapricornus-2.7 to -2.6   
SaturnCapricornus+0.3 to +0.5   
UranusAries5.7   
NeptuneAquarius+7.8Opposition5:00AM EDT9/14

September Moon

The New Moon of September is on the 6th at 8:51PM EDT. It is the beginning of Lunation 1221 which ends 29.46 days later with the New Moon of October 6 at 7:05AM EDT. The Full Moon of September is on the 21st at 8:01PM EDT. It is commonly known as “Fruit” Moon. In colonial times, the Full Moon of September was called the “Harvest” Moon and in Medieval England, it was the “Barley” Moon.” Chinese call it “Chrysanthemum” Moon and Celts named it the “Singing” or “Blood” Moon.

The “Harvest Moon” occurs in September because it is the full moon closest to the Autumn Equinox at 3:22PM on the 22nd. Since it occurs slightly before the equinox, it is thought to occur during the three months of Summer which began on the Summer Solstice. It is the 4th Full Moon is those 3 months which made the August Full Moon a “Blue Moon”.

Of the 13 Grandmother Moons during each year, the Anishinaabe (Odawa & Ojibwe) people recognize the 10th Moon as “Waatebagaa-giizis” (Leaves Turning Moon). It has the following associated cultural teaching that explains the cycle of life and nature for the 10th Moon. “This is a time when it is said that all of creation makes offerings to Mother Earth. The beautiful colors of fall and the awakening of spirits happens during this…..moon.”

Lunar Perigee distance (minimum lunar distance) is 228,951 miles on the 11th at 5:53AM EDT. Lunar Apogee (maximum lunar distance) is on September 26 at 6:00PM EDT, The Moon will be 251,432 miles from Earth.

PlanetConstellationMagnitudeMoon PassagesMoon PhaseMoon Age
SunLeo-26.88:51PM EDT, 9/6New0 days
MercuryVirgo0.15.9°NNE, 10:00PM EDT, 9/8Waxing Crescent2.05 Days
VenusLibra-4.03.7°N, 2:00AM EDT, 9/10Waxing Crescent3.21 Days
MarsVirgo1.83.8°NNE, 4:00PM EDT, 9/7Waxing Crescent0.80 Days
JupiterCapricornus-2.63.8°SE, 6:00AM EDT, 9/18Waxing Gibbous11.38 Days
SaturnCapricornus0.43.7°SE, 1:00AM EDT, 9/17Waxing Gibbous10.17 Days
UranusAries5.71.26°SE, 2:00PM EDT, 9/24Waning Gibbous17.71 Days
NeptuneAquarius7.83.7°SE, 9:00AM EDT, 9/20Waxing Gibbous13.51 Days


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