2023, September 10: Moon-Pollux Conjunction, Venus as a Crescent

2020, December 11: One hour before sunrise, the crescent moon is to the upper right of brilliant Morning Star Venus.


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:26 a.m. CDT; Sunset, 7:09 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Summaries of Current Sky Events

Summary for Venus as a Morning Star, 2023-24

Here is today’s planet forecast:

Morning Sky

Chart Caption – 2023, September 10: The moon is near Pollux and above Venus this morning. Castor, Procyon, Sirius, and Betelgeuse are nearby.

An hour before sunrise, look into the eastern sky for a thinning crescent moon, 18% illuminated.  It is 4.4° to the lower left of Pollux, one of the Gemini Twins.  The other Twin, Castor, is 4.5° to the upper left of Pollux.

Photo Caption – Venus and the crescent moon. Notice the “earthshine” on the night portion of the moon.

Look carefully at the moon for earthshine, a gentle glow between the crescent’s cusps or horns.  This effect is from sunlight that is reflected from Earth’s oceans, clouds, and land.

Morning Star Venus is nearly 19° below the lunar crescent.  It continues to brighten as it rises earlier each morning.  Through a spotting scope or telescope, the planet displays a crescent, 20% illuminated.

The lunar phase and the Venusian phase are about the same illumination, both showing crescents.  While the moon’s phase is thinning or waning, Venus’ phase is growing, but waxing and waning are not used with Venus.  Venus’ phase is currently named morning crescent.

Sirius, night’s brightest star, is about 40° to the right of Venus and nearly the same altitude.  Venus and the other planets do not pass closely to Sirius because the star is nearly 40° from the ecliptic, the plane of the solar system, where the planets move against the background stars.

For the rest of the month, Venus and Sirius are about the same altitude – height above the horizon – during morning twilight.

Note Procyon, known as the little Dog Star, above an imaginary line from Venus to Sirius.  Its name means “before the dog,” as it rises about thirty minutes before Sirius, the Dog Star, at the mid-northern latitudes.

Rosy Betelgeuse, Orion’s shoulder or armpit, is above Sirius.

Chart Caption – 2023, September 10: Jupiter is high in the south-southwest, retrograding in front of Aries, before sunrise.

Jupiter, morning’s third brightest body after the moon and Venus, is high in the south-southwest.  It continues to retrograde, seem to move westward compared to Aries’ distant stars.  It is 13.6° to the lower left of Hamal, the Ram’s brightest star, and 11.3° to the upper right of Menkar, Cetus’ nostril.

Photo Caption – Jupiter (NASA Photo)

At 4:52 a.m. CDT, Jupiter’s Great Red Spot is at the center of the planet in the southern hemisphere, when viewed through a telescope.

Photo Caption – Mercury as Never Seen Before. (NASA photo)

Mercury is racing into the morning sky for its best morning appearance of the year.  It rises over thirty minutes before daybreak.  It is not yet far enough from the sun’s brightness for easy viewing.

 Evening Sky

Photo Caption – 2007, December 1: Late winter in the northern hemisphere shows clouds above the northern polar cap and some above the southern cap. (NASA Photo)

Mars is sliding into brighter evening twilight.  It is fainter than expected and not easily visible.

Chart Caption – 2023, September 10: Saturn is in the southeast before sunrise.

Saturn rises over thirty minutes before the sun sets.  By two hours after sundown, Saturn is nearly 25° above the southeast horizon. It is retrograding in front of Aquarius. The Ringed Wonder nearly makes an equilateral triangle with Skat, the Aquarian’s leg, and Lambda Aquarii (λ Aqr on the chart).

During the night Saturn appears farther west, in the south around midnight.  The planet sets during morning twilight in the west-southwest.

Bright Jupiter appears above the eastern horizon over two hours after nightfall.  At 12:43 a.m. CDT tomorrow (September 11), the Red Spot is back in the center of the planet, two Jupiter days after this morning’s sighting.  By tomorrow morning the planet is high in the south-southwest.


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