2023, August 19: Evening Moon, Imitation Jovian Satellite


August 19, 2023: The moon is easily seen in the western sky after sundown.  Through a telescope, a distant star plays an imitation moon of Jupiter.

Photo Caption – 2021, January 15: The thin waxing moon with earthshine, reflected sunlight from Earth’s features gently illuminates the lunar night.


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:03 a.m. CDT; Sunset, 7:44 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

Here is today’s planet forecast:

Morning Sky

Chart Caption – 2023, August 19: Jupiter is in the southeast before sunrise.

An hour before sunrise, bright Jupiter is in the southeastern sky.  It seems to be leading a contingent of bright stars westward.  Jupiter is to the right of the Pleiades star cluster while it appears to the upper right of Aldebaran and the Hyades star cluster. Jupiter is moving eastward in front of Aries, 13.3° to the lower left of Hamal, meaning “the full-grown lamb,” and 11.3° to the upper left of Menkar, Cetus’ nostril.

Chart Caption – 2023, August 19: Through a telescope, Sigma Arietis (σ Ari) looks like one of Jupiter’s brighter satellites.

Through a telescope, the star Sigma Arietis (σ Ari on the chart) appears in line with the four other large moons, known as the Galilean satellites.  The star seems to imitate a fifth large moon.  See yesterday’s article for more details.

Chart Caption – 2023, August 19: Saturn is in the west-southwest before sunrise, near Skat and Lambda Aquarii (λ Aqr).

At this hour, Saturn is less than 20° up in the southwest.  It is retrograding – the illusion of moving westward against the distant starfield – in front of Aquarius, 8.0° to the right of Skat, the Aquarian’s leg, and 7.6° to the lower right of Lambda Aquarii (λ Aqr).  This trio nearly forms and equilateral triangle.

In a few days, Fomalhaut, the mouth of the Southern Fish, is too low to be seen at this time interval.  This morning it is nearly 20° to the lower left of Saturn and less than 10° above the horizon.

2020, June 16: The crescent moon is over 36° to the upper right of Venus.

Venus is racing into the morning sky, today rising twenty-seven minutes before the sun.

In the accompanying image from 2020, Venus was nearly 20° from the sun and appeared above the eastern horizon nearly an hour before the sun.  This morning Venus is nearly 12° from the sun and theoretically visible from a location with a clear view at the horizon.

The first easy view, resembling the scene in the image occurs in three days when Venus rises forty-nine minutes before the sun, when the planet is about 3° above the eastern horizon at 30 minutes before daybreak.

Evening Sky

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

Mercury is overtaking our planet, passing between our world and the sun on September 6th and then an appearance in the morning sky. After last night’s appearance with the crescent moon,

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 lost in bright evening twilight, setting over seventy minutes after sundown.

Chart Caption – 2023, August 19: The moon is in the western sky with Virgo after sundown.

An hour after sunset, the evening crescent moon, 12% illuminated, is less than 10° above the western horizon.  It is in front of Virgo, 4.3° to the lower right of Porrima, also known as Gamma Virginis, and nearly 20° to the lower right of Spica, the constellation’s brightest star.

Photo Caption: 2021, May 13: The crescent moon is 3.2° to the upper left of Mercury.

Look for earthshine on the moon between the lunar cusps or horns that is nighttime on the moon.  This gentle illumination is sunlight reflected from Earth’s oceans, clouds, and land.  It is similar to moonlight softly lighting up terrestrial features.  This begins when the phase is more that 30% lit.

Chart Caption – 2023, August 19: Two hours after sunset, Saturn is in the east-southeast.

Saturn nears its opposition date, when it rises at sunset. This evening the Ringed Wonder peeks above the horizon twenty minutes after nightfall.  By two hours after sunset, it is over 15° above the east-southeast horizon.  Skat and Lambda Aquarii are nearby. 

During the night the planet appears farther westward. Less than three hours after Saturn rises, before midnight at most locations.

Jupiter rises in the eastern sky.  By tomorrow morning, the Jovian Giant is high in the southeast.



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