2023, July 24: Spiked Moon, Evening Twilight Horseplay

July 24, 2023: The evening moon appears near Spica.  The views of Venus, Mercury, and Mars are affected by bright evening Twilight.  Jupiter and Saturn are visible before sunrise.

2021, May 13: Brilliant Venus, Mercury, and the crescent moon in the evening sky.
Photo Caption: 2021, May 13: Brilliant Venus, Mercury, and the crescent moon in the evening sky.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:37 a.m. CDT; Sunset, 8:17 p.m. CDT.  Check local sources for sunrise and sunset times for your location.  Times are calculated by the U.S. Naval Observatory’s MICA computer program.

Summaries of Current Sky Events
SUMMARY FOR VENUS AS AN EVENING STAR

Here is today’s planet forecast:

Morning Sky

2023, July 24: Jupiter is in the east-southeast before daybreak.
Chart Caption – 2023, July 24: Jupiter is in the east-southeast before daybreak.

An hour before sunrise, bright Jupiter is halfway up in the east-southeast.  It is slowly moving eastward in front of Aries, 12.2° below Hamal, the pattern’s brightest star, and 11.5° to the upper left of Menkar, Cetus’ nostril.

Look for the Pleiades star cluster, over 18° to the lower left of the Jovian Giant.  Use a binocular to see the individual stars in the stellar bundle.

Jupiter
Photo Caption – Jupiter (NASA Photo)

At 5:09 a.m. CDT, Jupiter’s Great Red Spot is visible through a telescope at the center of the planet in the southern hemisphere. This is about thirty minutes before daybreak in Chicago.  The long-lived atmospheric disturbance is visible at this level of twilight, but the appearance occurs in a darker sky for sky watchers at more westerly locales.

2023, July 24: Saturn is in the south-southwest before sunrise.
Chart Caption – 2023, July 24: Saturn is in the south-southwest before sunrise.

During morning twilight, Saturn is 35° above the south-southwest horizon.  It is noticeably dimmer than Jupiter, but the Ringed Wonder is nearly twice as far away as the Jovian Giant.  This reduces Saturn’s brightness compared to Jupiter by one-fourth.  Both planets reflect 34% of the sunlight that reaches them.  Less sunlight reaches Saturn and the return reflected light makes Jupiter nearly 20 times brighter than the more-distant ringed world.

Saturn is retrograding in front of Aquarius’ dim stars, 7.2° to the upper right of Skat and 5.9° to the lower right of Lambda Aquarii (λ Aqr on the chart).  Use a binocular to see the dimmer star field.  Look for Saturn’s place compared to the reference stars each morning to see the planet’s western change.

Evening Sky

2023, July 24: Venus, Mercury, Mars, and Regulus are in the western sky during bright twilight.
Chart Caption – 2023, July 24: Venus, Mercury, Mars, and Regulus are in the western sky during bright twilight.

Brilliant Venus is quickly leaving the evening sky.  It can be spotted shining through the western evening twilight soon after nightfall.  It sets less than an hour after sundown and before Nautical Twilight, when the sun is 12° below the horizon. At this twilight phase, the horizon can still be distinguished.

2023, July 24: Venus, Mercury, and perhaps Regulus are visible through a binocular after sundown.2023, July 24: Venus, Mercury, and perhaps Regulus are visible through a binocular after sundown.
Chart Caption – 2023, July 24: Venus, Mercury, and perhaps Regulus are visible through a binocular after sundown.

At thirty-five minutes after sundown, Venus is less than 5° above the western horizon.  With a binocular, find Mercury 6.3° to Venus’ upper right and possibly Regulus, 4.7° above the Evening Star.

Venus is overtaking our planet, passing by on August 13th.  Then it quickly moves into the morning sky for an appearance that lasts through spring of 2024.

Mercury passes Venus in three nights during bright twilight.  A binocular is needed to see the conjunction.

Mars is a challenge to see, 11.3° to Venus’ upper left.  First, the planet is dimmer, fainter than might be expected.  Second, the sky has no bright reference star or planet nearby. By an hour after sunset, Mars is less than 10° above the western horizon, setting about fifty minutes later.  A binocular is still needed to locate it.

2023, July 24: The crescent moon and Spica are in the southwest during evening hours.
Chart Caption – 2023, July 24: The crescent moon and Spica are in the southwest during evening hours.

This evening an hour after sundown, the crescent moon, 42% illuminated, is over 20° up in the southwest, 2.6° to the upper right of Spica, Virgo’s brightest star, meaning “the ear of corn.” The moon is at its evening half phase (First Quarter) tomorrow at 5:07 p.m. CDT.

Spica is the tenth brightest star visible from the mid-northern latitudes.  The star is 250 light years away and shines with the brightness of nearly 2,000 suns. Saturn rises about fifteen minutes before Mars sets.  By three hours after night fall, the Ringed Wonder is nearly 15° up in the east-southeast.  From Earth’s rotation, it appears in the south-southwest tomorrow morning.

Saturn rises about fifteen minutes before Mars sets.  By three hours after night fall, the Ringed Wonder is nearly 15° up in the east-southeast.  From Earth’s rotation, it appears in the south-southwest tomorrow morning.

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