2023, September 20: Queen of Morning, Mercury’s Best, Scorpion Moon

Photo Caption – 2015, September 21: Venus, Jupiter, Mars, Regulus


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:36 a.m. CDT; Sunset, 6:52 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 20: Venus and Sirius are about the same altitude – height above the horizon – at during morning twilight.

Saturn sets in the west-southwest about two hours before sunrise.  An hour earlier, Venus is low in the eastern sky and Saturn is 10° above the horizon.  Venus and Saturn are 180° apart October 10th, when Saturn sets as Venus rises.  The Ringed Wonder is challenging to see near the horizon, so the visual opposition occurs before the geometric event.  What is the last date that you see them in the sky at the same time?

Look for Saturn after sunset when it is easily located at a more convenient hour.

The queen of the morning sky is brilliant Venus. The Morning Star rises over three hours before the sun.  By one hour before daybreak, the planet is nearly 25° above the east horizon. 

The planet is stepping eastward in front of Cancer’s dim stars, 14.2° to the upper right of Regulus, Leo’s brightest star. Watch Venus close the gap to Regulus. Their conjunction occurs October 9th.

Through a spotting scope or telescope, Venus displays a morning crescent phase that is 28% illuminated.

Through month’s end Venus and Sirius, night’s brightest star, are nearly the same altitude – height above the horizon – during morning twilight.  The Dog Star, in the south-southeastern sky, is about 40° to the right of Venus. The planet is over 20 times brighter than the star.

Look for Procyon, known as the Little Dog Star, above a line from Venus to Sirius.

Chart Caption – 2023, September 20: Venus, Mercury, and Regulus are in the eastern sky before daybreak.

Mercury dances into the eastern morning sky for its best morning appearance of the year.  It is 9.5° to the lower left of Regulus.  At one hour before daybreak, it is about 5° above the eastern horizon.  Wait another fifteen minutes to see the planet a little higher in the sky.

Chart Caption – 2023, September 20: Bright Jupiter is high in the southwest, retrograding in Aries, before sunrise.

Bright Jupiter rises during the evening and by morning twilight it is high in the southwest, retrograding in front of Aries, 13.4° to the lower left of Hamal, the Ram’s brightest star, 11.2° to the upper right of Menkar, the Sea Monster’s nostril, and 16.1° to the lower right of the Pleiades star cluster, part of Taurus.

After Venus, Jupiter is second brightest this morning, about three times brighter than Sirius.

Earth passes between Jupiter and the sun on November 2nd.  The planet rises at sunset and sets at sunrise. The Venus-Jupiter opposition occurs December 10th, when Jupiter sets as Venus rises.

Photo Caption – Jupiter (NASA Photo)

Earlier this morning at 3:07 a.m. CDT, Jupiter’s Great Red Spot is visible at the center of the planet through a telescope.  The planet is high in the south-southeast at this hour.

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 the most-difficult-to-see planet among the five brightest solar system worlds.  It sets less than forty-five minutes after sundown.  It is dimmer than might be expected and hiding in bright evening twilight.

Chart Caption – 2023, September 20: One hour after sundown, Saturn is in the southeast with Aquarius.

Saturn rises about an hour before sundown, and by an hour after the sun sets, it is nearly 20° up in the southeast.  It is retrograding in front of Aquarius, 9.6° to the upper right of Skat, the leg, and 9.9° to the right of Lambda Aquarii (λ Aqr on the chart).  Use a binocular to see the starfield, although the planet and the reference stars are not in the same binocular field of view.  Begin at Saturn and move toward the individual star.

Chart Caption – 2023, September 20: The waxing crescent moon is in the southwest after sundown with Scorpius.

The waxing crescent moon, 31% illuminated, is less than 15° up in the southwest, in front of Scorpius. The lunar orb is bright enough to illuminate terrestrial features and cast shadows on the ground. 

This evening the lunar crescent is 3.5° to the lower left of Dschubba, the Scorpion’s forehead, and 4.6° to the lower right of Antares, meaning “the rival of Mars.”

Later this evening, the moon occults or eclipses Al Niyat, also known as Sigma Scorpii.  In celestial artwork, Antares marks the Scorpion’s heart, making Al Niyat an artery.

Jupiter rises about two hours after sundown and it is high in the southwest during morning twilight tomorrow. 

This evening at 10:58 p.m. CDT, the Great Red Spot is again at the center of the planet, two Jupiter-days after this morning’s appearance.  During this evening’s display, the planet is about 25° up in the east from mid-America.


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