2021, September – October: Venus and the Scorpion

Venus moves through the classic Scorpion (Libra, Scorpius, and Ophiuchus) during the next 46 days.  The planet is south of the ecliptic, appearing in regions of the constellations that we might not expect to see it. Venus closes in on Earth. The observing interval occurs at nearly mid-twilight so that dimmer stars are easier to see than earlier in the apparition.  Venus sets later each evening and brightens in the sky. On October 9, the moon is near Venus and Delta Scorpii. A week later, Venus passes Antares. Look for an evening half phase through a telescope near the end of October and the evening greatest elongation.

2021, September 18 - October: Venus moves through the classic Scorpion (Libra, Scorpius, and Ophiuchus).
Chart Caption – 2021, September 18 – October: Venus moves through the classic Scorpion (Libra, Scorpius, and Ophiuchus).

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Look for the planet with the stars in the southwest about 45 minutes after sunset.  The chart above shows the planet’s position each evening.

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

On September 18, Venus moves into Libra.  It sets at the end of evening twilight and continues to set after twilight ends until late December.

2021, September 23: Venus passes 2.0° to the lower left of Zubenelgenubi.
Chart Caption – 2021, September 23: Venus passes 2.0° to the lower left of Zubenelgenubi.

Venus passes 2.0° below Zubenelgenubi, the “southern claw ” (September 23).

On October 7, Venus moves into the official boundary of Scorpius.

2021, October 9: The crescent moon, joins Venus. The lunar slice is to the upper left of the planet, while Venus is lower left of Delta Scorpii (δ Sco ).
Chart Caption – 2021, October 9: The crescent moon, joins Venus. The lunar slice is to the upper left of the planet, while Venus is lower left of Delta Scorpii (δ Sco ).

Two nights later (October 9), the crescent moon, 17% illuminated, joins Venus.  The lunar slice is 2.6° to the upper left of the planet, while Venus is 0.7° to the lower left of Delta Scorpii (δ Sco on the charts.

2021, October 15: Venus is 1.4° to the lower left of dim Rho Ophiuchi (ρ Oph). Use a binocular. Notice that Venus, Antares, and Sigma Scorpii (σ Sco) make a triangle.
Chart Caption – 2021, October 15: Venus is 1.4° to the lower left of dim Rho Ophiuchi (ρ Oph). Use a binocular. Notice that Venus, Antares, and Sigma Scorpii (σ Sco) make a triangle.

On October 15, Venus crosses into Ophiuchus for one evening.  Then it is back inside the boundary of Scorpius on the next evening.  The planet is 1.4° to the lower left of dim Rho Ophiuchi (ρ Oph).  Use a binocular.  Notice that Venus, Antares, and Sigma Scorpii (σ Sco) make a triangle.

2021, October 16: Venus passes Antares. In this simulated binocular view note the locations of the planet with the starry background.
Chart Caption -2021, October 16: Venus passes Antares. In this simulated binocular view note the locations of the planet with the starry background.

On the next evening (October 16), Venus passes Antares.  Venus is 1.4° to the upper right of the star.

Venus moves back into Ophiuchus on October 21.

2021, October 29: Venus is at its greatest elongation.
2021, October 29: Venus is at its greatest elongation.

Venus reaches is at its greatest separation from the sun on October 29.  Known as the greatest elongation, Venus is 27.0° from the sun.  Through a telescope, Venus displays an evening half phase. It sets over 2 hours (136 minutes) after sundown.  After two more nights Ophiuchus, Venus moves into Sagittarius.

Venus as an Evening Star Article



Categories: Astronomy, Sky Watching

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