2021, November – December: Venus, Sagittarius

By Jeffrey L. Hunt on March 16, 2021 • ( 0 )

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2021, November and December, Venus moves eastward through Sagittarius.

For nearly 40 days, Venus moves eastward among the stars of Sagittarius. During early December, it reaches its greatest brightness. It gleams in the southwestern sky after sunset. On November 7, the moon joins Venus. A second grouping occurs on December 6. The planet and the moon appear together in likely their best show of the apparition. Venus is very bright with a crescent moon under it. The planet stops moving eastward after mid-December and begins its rapid descent from the evening sky.

Look for Venus low in the southwest about 45 minutes after sunset.

To follow the planet’s eastward trek through the constellations, see this semi-technical summary.

On November 6, Venus passes 3.1° to the upper right of Alnasl (γ Sgr on the chart). The star represents the “point of the arrow,” of Sagittarius’ mythological creature.

2021, November 7: The crescent moon is 3.9° to the lower right of the brilliant planet.

The next evening (November 7), the moon makes its monthly grouping with the brilliant planet. The crescent moon is 3.9° to the lower right of the brilliant planet.

Venus continues its eastward trek. On November 10, it passes 2.6° to the upper right of Kaus Media (δ Sgr), “the middle part of the bow” of Sagittarius. Two nights later, it passes Kaus Borealis (λ Sgr), “the northern part of the bow.”

Venus passes 0.2° of Phi Sagittarii (φ Sgr) on November 16. A binocular helps to separate the planet and the star in the field of view.

Three nights later, the brilliant planet passes Nunki (σ Sgr), “the yoke of the sea.”

The planet continues to set later, appearing higher in the south-southwest at nightfall.

2021, December 7: Venus is at its midpoint of its period of greatest brightness. The planet is approaching Earth.

On November 27, the planet begins its interval of greatest brightness until December 14. The planet’s brightness will increase slightly during this interval of time, but likely the change is invisible to the unaided eye.

2021, December 6: Brilliant Venus is 3.2° above the crescent moon.

While not the closest grouping of Venus and the moon, the December 6 pairing occurs when the planet is very bright. The moon phase is only 10% illuminated. Use a tripod-mounted camera and a time exposure to capture earthshine on the moon. Through a telescope, the moon is only 24% illuminated.

On December 18, the planet stops its eastward trek and it begins to retrograde as it moves rapidly toward its inferior conjunction. By December 26, Venus is setting again at the end of evening twilight. It loses about 7 minutes of setting time each evening.