2023, July 28: Morning Stars, Evening Gibbous Moon, Mercury-Regulus Conjunction


July 28, 2023: Before sunrise, Jupiter shines above bright morning stars.  The evening gibbous moon is near Antares.  Mercury passes Regulus.


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:41 a.m. CDT; Sunset, 8:13 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.

2020, August: Sirius is visible, without a binocular, in the east-southeast, 46 minutes before sunrise.

Sirius Watch: Sky watchers at latitude 25° north should be spotting Sirius low in the east-southeast at about forty minutes before sunrise for the first time after its disappearance into bright sunlight during the spring. 

See the article about Sirius’ heliacal rising during 2023

The first appearance is dependent on weather.  Periods of morning clouds or rainy days can delay spotting the star.  An exceptionally clear sky and sighting from an elevated structure or hillside can accelerate spotting Sirius.

Summaries of Current Sky Events

Here is today’s planet forecast:

Morning Sky

Chart Caption – 2023, July 28: During morning twilight, Jupiter appears above a bright congregation of stars that are prominent during February evenings.

Bright Jupiter is over halfway up in the east-southeast an hour before sunrise.  It is above bright stars that are prominently placed in the south during February.  This morning’s sky has the appearance of a November evening.  The Jovian Giant seems to be leading the bright congregation of stars westward.

The eastern sky has nearly half of the brightest dozen stars that are visible from the mid-northern latitudes, including Capella, Rigel, Betelgeuse, Aldebaran, and Pollux.

Capella – meaning “the little she-goat,” is about 40° up in the northeast, while Orion’s Betelgeuse and Rigel are near the eastern horizon. 

Pollux and Castor are near the horizon in the east-northeast.

Aldebaran, Taurus’ brightest star, is nearly 30° up in the east. The Pleiades star cluster is about 14° above the Bull’s eye and 18° to the lower left of the Jovian Giant.  It is a delightful view through a binocular. 

Jupiter moves slowly eastward in front of Aries. The planet revolves around the sun nearly every twelve years, meaning it travels through 360° along the ecliptic – the plane of the solar system – in that interval.  It appears against the constellations behind the orbital path known as the zodiac.   This morning’s view provides a preview of the planet’s place during the next few years.

Jupiter passes Aldebaran on June 10, 2024, and Pollux on October 10, 2025. A bright daytime conjunction with Venus occurs May 23, 2024, followed by a conjunction before sunrise on August 12, 2025, in the middle of Gemini.

Chart Caption – 2023, July 28: Saturn is in the south-southwest before daybreak.

Farther westward, Saturn – dimmer than Jupiter, but brighter than most stars in the sky this morning – is over 30° above the south-southwest horizon.  It is retrograding in front of Aquarius, 7.2° to the upper right of Skat and 6.1° to the lower right of Lambda Aquarii (λ Aqr on the chart).  Use a binocular to see the starfield with the planet.

Saturn takes nearly thirty years to travel one circuit through the zodiacal stars. The planet actually is not moving westward in its orbit.  This illusion occurs when Earth passes between the sun and the more distant worlds.

Evening Sky

Chart Caption – 2023, July 28: Mercury and Regulus are close together through a binocular after sundown.

Brilliant Venus is plunging into bright sunlight.  It passes between Earth and the sun on August 13th and quickly moves into the morning sky.  This evening the planet sets thirty-six minutes after the sun.  Find it earlier during bright twilight.  By twenty minutes after nightfall, the planet is near the western horizon.

Mercury, nearing its greatest separation from the sun, known as its greatest elongation, is less than 4° above the west-northwest horizon at forty-five minutes after sundown. It is dimmer each evening.  Mercury passes 0.2° to the lower left of the star Regulus. This conjunction is challenging to see.  Use a binocular and look along the horizon.

At the same time, Mars, dimmer than Regulus, is over 10° to the upper left of Mercury.  Definitely not visible to the unassisted eye, use a binocular.  It is nearing the end of its two-year apparition.

Chart Caption – 2023, July 28: An hour after sunset, the moon is near Antares, Scorpius’ brightest star.

An hour after sundown, the bright evening gibbous moon, 82% illuminated, is about 20° up in the south.  The moon’s light overwhelms the dimmer stars, so a binocular is needed to see the Scorpion’s starfield near the lunar orb.

Antares, meaning “the rival of Mars” and represents the Scorpion’s heart, is 4.8° to the upper right of the moon.

Look for Shaula – meaning “the cocked-up part of the tail” – and Lesath – meaning “the sting” – close together, less than 15° to the lower left of the moon.  They are sometimes known as the “Cat’s eyes” because of their proximity and similar brightness, although Shaula is noticeably brighter than Lesath.

Chart Caption – 2023, July 28: Saturn is in the east-southeast at three hours after sundown.

Saturn crosses the horizon about 80 minutes after the sun sets.  It is rising earlier each evening as Earth over takes the planet and passes between the sun and the Ringed Wonder in about a month.  On August 27th, the opposition date, the planet rises at sunset, appears in the south around midnight, and sets in the west at sunrise.



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