2021, December 18:  Venus Retrogrades

December 18, 2021:  Venus begins to retrograde this evening.  It appears in the southwest after sunset, along with bright Jupiter and Saturn. The moon is caught between the Bull’s horns this evening.  In the morning sky, Mars passes the star Graffias.

2021, December 18: Mars passes 1.0° to the lower right of Graffias before sunrise.
Chart Caption – 2021, December 18: Mars passes 1.0° to the lower right of Graffias before sunrise.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:13 a.m. CST; Sunset, 4:22 p.m. CST.  Check local sources for sunrise and sunset times for your location.

This evening Venus stops moving eastward along the plane of the solar system, the ecliptic, and begins to move westward or retrograde compared to the starry background and in ecliptic longitude.

The planet is in progress of a triple conjunction with Mars.  Such conjunctions occur when the faster moving planet over takes the slower moving planet as they are moving eastward along the ecliptic.  The second occurs when the faster is retrograding.  The final conjunction occurs when the faster moving planet resumes its eastward motion and passes the slower moving planet again.

The first conjunction of Venus and Mars occurred on July 12 as Mars headed toward its solar conjunction on October 7. The Red Planet is emerging from bright morning twilight in the southeastern sky.  After Venus passes between the sun and Earth (inferior conjunction) during early January, it seems to jump into the morning sky as it retrogrades along the ecliptic.  It passes Mars for the second conjunction on February 16, 2022. 

As Venus moves eastward it passes Mars for the third conjunction on March 6, 2022.

Another such triple conjunction of these two planets occurs during 2027 and 2028.

Morning Sky

Mars is visible low in the morning sky before sunrise.  Here’s how to find it:

At about 45 minutes before sunrise, the bright star Spica is about one-third of the way up in the sky in the south-southeast.  Do not confuse this blue star with topaz Arcturus that is over halfway up in the southeast.

The Scorpion’s two pincer stars, Zubeneschamali and Zubenelgenubi, are at about the same height about the horizon, over 20° to the lower left of Spica. (Today, the two stars are part of the constellation Libra.) Mars is over 16° below Zubeneschamali.  The Red Planet is nearly 10° above the southeast horizon.  It is brighter than the pincers, but it is immersed in growing morning twilight. A binocular may help you find it.

This morning Mars is passing Graffias, “the crab,” marked as the second brightest star in Scorpius.  The Red Planet is 1.0° to the lower right of the star.

If we include the classic pincers, the Scorpion is reaching across the southeastern horizon.  Its head is just above the skyline, but the remainder of the body and the nasty sting are still below it.

Evening Sky

2021, December 18: Venus begins to retrograde and open a wider gap to Saturn. Jupiter is to the upper left of the Ringed Wonder.
Chart Caption – 2021, December 18: Venus begins to retrograde and open a wider gap to Saturn. Jupiter is to the upper left of the Ringed Wonder.

The evening planet trio – Venus, Jupiter, and Saturn – is in the southwestern sky after sunset.  Initially, Jupiter might be the first “star” you see.  One hour after sunset, it is over one-third of the way up in the south-southwest.  Brilliant Evening Star Venus is about 11° up in the southwest.  Saturn is between the two evening showpieces.  It is 14.1° to the upper left of Venus and 17.5° to the lower right of Jupiter.

As noted earlier, Venus begins to retrograde this evening.  The gap to Saturn increases until Venus disappears into bright sunlight early next year.

This evening the moon seems to be caught between the Bull’s horns.  Tomorrow morning the moon is officially at its Full phase.

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