2023, June 21:  Summer Solstice, Rare Venus, Mars, Moon Grouping


June 21, 2023:  The solstice occurs today, signaling the beginning of astronomical summer in the northern latitudes. From the Americas, not until 2028 will Venus, Mars, and the moon appear this close.

Photo Caption – 2023, June 21: Venus, Mars, and crescent Moon after nightfall.


by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:16 a.m. CDT; Sunset, 8:29 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.

Photo Caption – 2022, March 16: Sunrise Approaches

The sun reaches its most northerly point today at 9:58 a.m. CDT, signaling the beginning of astronomical summer in the northern hemisphere. This reflects Earth’s revolution around the central star and our planet’s tilt. For residents at the latitude of 23.5° North, the sun travels overhead today at noon.  The sun is most northerly today in its rising and setting.  The season runs ninety-three days, fifteen hours, and fifty-two minutes.  Until the autumnal equinox on September 23rd, daylight loses three hours, five minutes, rising and setting farther southward along the horizon.

Summaries of Current Sky Events


Here is today’s planet forecast:

Morning Sky

Chart Caption – 2023, June 21: Jupiter is in the east before sunrise, with Hamal to the upper left.

An hour before daybreak, bright Jupiter is nearly 20° above the east horizon.  It is brighter than all the other stars in the sky this morning.

The Jovian Giant is slowly moving eastward in front of Aries, 11.1° to the lower right of Hamal, the constellation’s brightest star.

Have you seen the Pleiades star cluster over 10° above the east-northeast horizon at this hour.  Use a binocular to initially locate the stellar bundle.  Can you see it without the binocular’s assist?

Chart Caption – 2023, June 21: Saturn is in the south-southeast during morning twilight above the star Fomalhaut.

Saturn is over 30° above the south-southeast horizon, retrograding in front of Aquarius.  It is above Fomalhaut, meaning “the mouth of the southern fish,” that is about halfway from the horizon to the Ringed Wonder.

Retrograde motion is an illusion from our faster moving Earth overtaking a planet farther from the sun.  The line of sight, that normally shifts eastward from night to night, shifts westward making the planet appear to backup against the background stars.

Mercury continues its retreat from the morning sky and into bright sunlight. This morning it rises forty-five minutes before daybreak.

Evening Sky

Chart Caption – 2023, June 21: Venus, Mars, and the crescent moon group together in the west after sundown.

Venus, Mars, and the crescent moon make a beautiful grouping in the western sky after sunset.  Venus, approaching its phase of greatest brightness, is “that bright star” in the west after nightfall.  This evening an hour after sundown, the planet is less than 20° up in the west and 2.9° to the lower left of the lunar crescent that is 14% illuminated.  Mars is 4.5° to the upper left of Venus.  This is a scene to be captured by artists.

Chart Caption – 2023, June 21: Venus, Mars, and the lunar crescent are in the same binocular field of view.

Venus, Mars, and the lunar crescent easily fit within a 6.3° circle, meaning that the grouping fits into the same binocular field of view.  From the Americas, Venus, Mars, and the crescent moon are not bunched together this closely again until September 15, 2028. In the interim, only four Venus-Mars conjunctions occur, opening an opportunity for the moon to appear with them near conjunction events.  One conjunction occurs near the sun.  The others range from 7.1° – close enough to fit snugly into a binocular field of view – on November 30, 2027, to over 11° on February 7, 2024.  The fourth grouping, June 20, 2028, spans over 11°, occurring before sunrise with Mars and the lunar crescent low in the sky.

Through the binocular earthshine is easily spotted on the moon.  Move the binocular a little to the lower right.  Mars leaves the field, but Venus, Moon, and Beehive star cluster tightly fit into the same field of view.

Photo Caption – 2023, January 23: Evening crescent moon with earthshine.

Earthshine is sunlight reflected from Earth’s terrestrial features that gently illuminates the lunar night. The effect is visible to the unaided eye and easily captured during a short time exposure with a tripod-mounted camera.

The planets are moving eastward in front of Cancer.  A Venus-Mars conjunction seems imminent, but Venus slows and the closest it approaches Mars is 3.6° on the 30th. A quasi-conjunction occurs when the two planets’ closest gap is within 5.0°. Venus and Mars are moving toward Leo and its brightest star, Regulus. Mars passes the star on July 10th.  Venus does not reach Regulus, closing to the smallest gap on July 16th.

Tomorrow evening the crescent moon is farther eastward near the star Eta Leonis (η Leo on the chart).  The moon occults or eclipses the star from New Zealand and eastern Australia.



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