2023, October 23: Venus at Greatest Elongation

Astronomy, Sky Watching
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October 23, 2023: Venus moves to its farthest angular distance from the sun today, known as greatest elongation.  During morning twilight, the Morning Star passes Leo’s Chertan.

Venus and Jupiter in the western sky after sundown, March 1, 2023.
Photo Caption – Venus and Jupiter in the western sky after sundown, March 1, 2023.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:12 a.m. CDT; Sunset, 5:57 p.m. CDT.  Check local sources for sunrise and sunset times. Times are calculated by the US Naval Observatory’s MICA computer program.

Chart Caption – 2023, October 23: Venus’ orbit is shown at sunrise for the planet at the morning greatest elongation.

Venus reaches greatest elongation today.  The planet reaches the western-most extreme of its solar orbit, 46.4° from the sun.  The planet rises nearly four hours before sunrise. At sunrise, the planet is over 40° up in the southeast.  An hour earlier, when the sky is darker, Venus is 10° lower in the east-southeast.

Through a telescope, the planet is 50% illuminated, a morning half phase.  Notice the exaggerated size of the planet on the accompanying chart.  It resembles a waning half moon, known as Last Quarter.  While Venus’ phase continues to grow, lunar phase names such as waxing and waning are not used for Venus.

Until November 10th, the planet rises at today’s time interval.  As the planet moves toward solar conjunction next year, it rises later each morning.  By mid-December, Venus rises thirty minutes later than today’s rising time.

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, October 23: One hour before sunrise, Venus passes Chertan in Leo.

An hour before sunrise, brilliant Venus stands nearly 30° up in the east-southeast.  This morning, it passes Chertan in a wide conjunction.  The planet and the star are 9.9° apart. 

Venus seems to step past the distant stars in Leo.  Earlier this month, it passed Regulus, meaning “the prince,” Leo’s brightest star.  A week ago, it passed the star Rho Leonis (ρ Leo on the chart).  In this morning’s conjunction, Venus is too far away from Chertan for them to fit into the same binocular field.

Chertan is part of a triangle in Leo that marks the Lion’s haunches and tail, dotted by Denebola.  Regulus is at the bottom of a backwards question mark outlining the Lion’s head.  We see Leo in silhouette as a westward-facing creature.  During October each year, we see Leo in the eastern morning sky.  As Earth revolves around the sun, we see the constellation earlier in the night at each season.  By spring it is high in the south after sunset.

Chart Caption – 2023, October 23: During morning twilight, Jupiter is in the western sky.

Bright Jupiter, noticeably dimmer than Venus, is over 20° above the western horizon.  It is 12.0° to the left of Hamal, Aries’ brightest star.

Photo Caption – Jupiter (NASA Photo)

For sky watchers with telescopes, Jupiter’s Great Red Spot is at the center of the planet in the southern hemisphere at 5:17 a.m. CDT.

Jupiter is approaching opposition, meaning that Earth is between the planet and the sun.  When that occurs, the planet rises at sunset and sets in the west at sunrise.

Venus and Jupiter are at opposition, meaning they are 180° apart in the sky and Jupiter sets as Venus rises on December 10th.  This morning the two planets are over 121° apart.

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)

Mercury and Mars set shortly after the sun.  Mercury is moving into the western evening sky, while Mars is heading toward a solar conjunction.

Chart Caption – 2023, October 23: One hour after sunset, Saturn and the moon are in the south-southeast.

This evening the moon is near Saturn. At one hour after sundown, the lunar orb, 71% illuminated is about 25° above the south-southeast horizon and 6.8° to the lower right of Saturn.  The moonlight is too bright to see dimmer stars, although they can be seen through a binocular.

Fomalhaut, the mouth of the Southern Fish, is about 20° below Saturn and nearly 10° above the horizon.

Three hours after sunset, Saturn is in the south.  It sets a few hours after midnight.

At this hour, Jupiter is over 5° above the east-northeast horizon.  By two hours after sunset, the Jovian Giant is over 15° above the eastern horizon. By midnight, Jupiter is in the southeast and tomorrow morning it is again in the western sky when Venus gleams in the eastern sky.

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