September Skies by Dick Cookman

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

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

  • Comet Journals 

Comet C/2023 A3 (Tsuchinshan-ATLAS) is a 7th magnitude comet which is circling east of Sextans in September and will zip from Sextans, through Virgo and Serpens Caput, and into Ophiuchus in October. It may brighten drastically when approaching perihelion passage on September 27 and may briefly attain naked eye visibility at 1st magnitude. The comet passes perigee (closest to Earth) on October 12, lighting up the western evening sky. It will then circle through the summer triangle in Aquila, Cygnus, and Lyra for the next 6 months while retreating to its origin in the Oort Cloud. 

Comet 13P/Olbers (2024) is a short period 8th magnitude comet in Coma Berenices and will move eastward between Bootes and Virgo in September. It passed through perihelion on June 30 and was closest to Earth on July 20.

  • Mars Landers 

The Perseverance rover just embarked on a 1000 foot climb to surmount the rim of Jezero Crater where it has spent the last 3.5 years investigating the rocks and sediments covering the floor of the crater. The rover collected and has stockpiled 12 rock samples for eventual return to Earth. Recent budget cutbacks and hundreds of layoffs have jeopardized the return plan. NASA is now seeking proposals from the space agency’s centers and private industry for less costly options.

Blast from the past – Martian seismic data collected by the now retired Insight Lander was recently examined with sophisticated computer modeling which revealed huge amounts of buried water at depths exceeding 10 miles. Enough water is thought to exist to form a many miles deep worldwide ocean. Scientists do not know the origin of the water. Is it water or ice trapped during the formation of the planet or was some of the water salvaged when the Martian magnetic field deteriorated and permitted the ancient solar wind to blow away most of the planet’s early atmosphere and hydrosphere? In any event, it appears to be present and may eventually be accessed by future technology.

 Meteor Showers

Meteor showers in September include the September Perseids, the Sextanids, and the Delta Aurigids. All three are minor showers, occurring during crescent lunar phases which permit better viewing.

September 9: Perseids. Active September 5-17. Radiant 04h0m 47°, ZHR 5, 64 km/sec. Waxing Crescent Moon. Progenitor: Unknown comet

September 27: Sextanids. Active September 9-October 9. Radiant 10h08m 00°, ZHR ? Radio, 30 km/sec. Waning Crescent Moon. Progenitor: Apollo asteroid 2005 UD

September 28: Delta Aurigids. Active September 18-October 10. Radiant 05h28m +49°, ZHR 3, 64 km/sec. Waning Crescent Moon. Progenitor: Comet C/1911 N1 Kiess. 

  • Planet Plottings

Mercury (0.5 to -1.5) in Leo and Virgo, Mars (0.7 to 0.5) in Taurus and Gemini, Jupiter (-2.1 to -2.3) in Taurus, Saturn (0.6 to 0.7), in Aquarius), Uranus (5.7) in Taurus, and Neptune (7.8, in Pisces) are morning planets in the eastern sky in September. Mercury reaches greatest eastern elongation on the 4th when it is 18° from the rising Sun. It then drops toward the horizon as it approaches superior conjunction with the Sun on the 30th. Saturn is brightest at its Sept. 8 opposition with the Sun after which it moves into the evening sky. Neptune also has an opposition with the Sun on Sept. 20.

Brilliant Venus (+3.8) is an evening planet in the western sky. Venus moves from Virgo to Libra during September, rising higher above the western horizon in the process. After their respective oppositions, Saturn and Neptune appear in the eastern evening sky. 

Autumn begins after the equinox at 8:44AM EDT on the 22nd. Earth’s axis is oriented at precisely 90° from a line between Earth and the Sun, producing 12 hours of daylight and 12 hours of darkness.

Planet

Constellation(s)

Magnitude

Planet Passages

Time

Date
Sun

Gemini

-26.5

New Moon

 9:56PM EDT

9/2
Mercury

Leo to Virgo

0.5 to -1.5

 Max. West Elongation  Superior Conjunction

11:00PM EDT

5:00PM EDT

9/4

9/30
Venus

Virgo to Libra

-3.8
Mars

Taurus to Gemini

0.7 to 0.5
Jupiter

Taurus

-2.1 to -2.3
Saturn

Aquarius

0.6 to 0.7

Opposition

1:00AM EDT

9/8
Uranus

Taurus

5.7
Neptune

Pisces

7.8

Opposition

8:00PM EDT

9/20
  • September Moon

The September New Moon is in Leo on the 2nd at 9:56PM EDT. It marks the start of Lunation 1258 which ends 29.70 days later with the New Moon of October in Virgo on the 2nd at 2:49PM EDT. 

The Full Moon on the 17th occurs at 10:34PM EDT in Aquarius. It is a Supermoon which appears larger and brighter than normal because the Full Moon occurs less than 12 hours before lunar perigee, its minimum distance during the month. It is even brighter than August’s version when Full Moon & perihelion were almost 36 hours apart. September’s Full Moon is the Harvest Moon which is the full moon closest to the Autumn Equinox. It is also known as the Fruit Moon. Colonial Americans called it the “Harvest Moon”. To the Celts it was the “Singing Moon”. For the Chinese it is  the “Chrysanthemum Moon”. Medieval English thought of it as the “Barley Moon”, and the Anishinaabe (Odawa and Ojibwe) people of northern Michigan recognize it as “Waatebagaa-giizis” (Leaves Turning Moon). Ontario’s Earth Haven Farm presents cultural teachings explaining the cycle of life and nature of their 13 Grandmother Moons. “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 multicolored 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 (maximum lunar distance) – Sept. 5 at 10:54PM EDT. The Moon’s is at 252,408mi. (63.69 Earth radii). Lunar perigee –  Sept. 18, 9:22AM EDT. The Moon is at 222,007 mi. (56.02 Earth radii).                                                         

A waning crescent Moon sets with Mercury on the 1st. The waxing crescent Moon passes Venus on the 5th. A waxing gibbous Moon passes Saturn on the 17th and Neptune is passed by a waning gibbous Moon on the 18th after Full Moon. Uranus is next on the 22nd and the waning gibbous Moon passes Jupiter on the 23rd. The waning crescent Moon passes Mars on the 25th.

Planet

Constellation

Magnitude

Moon Passages

Moon Phase

Moon Age
Sun Gemini

-26.8

 9:56PM EDT, 9/2 New 0 Days
Mercury Leo

0.5

 5.0°N, 5:00AM EDT, 9/1 Waning Crescent 28.42 Days
Venus Virgo

-3.8

 1.2°S, 6:00AM EDT, 9/5 Waxing Crescent 0.34 Days
Mars Gemini

0.5

 5.0°N, 8:00AM EDT, 9/25 Waning Crescent 14.42 Days
Jupiter Taurus

-2.3

 6.0°N, 7:00PM EDT, 9/23 Waning Gibbous 13.88 Days
Saturn Aquarius

0.6

 0.3°N, 6:00AM EDT, 9/17 Waxing Gibbous 6.34 Days
Uranus Taurus

5.7

 5.0°N, 3:00AM EDT, 9/22 Waning Gibbous 11.21 Days
Neptune Pisces

7.8

 0.7° N, 4:00AM EDT, 9/18 Waning Gibbous 7.25 Days