October 7, 2021: The lunar crescent returns to the evening sky for a short visit in the western sky after sunset. The bright planet pack – Venus, Jupiter, and Saturn – are visible during the early evening.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 6:54 a.m. CDT; Sunset, 6:22 p.m. CDT. Check local sources for sunrise and sunset times for your location.
The very thin crescent moon, only 3% illuminated, reappears in the evening sky. Look for it low in the west-southwest at about 30 minutes after sunset. A binocular assists in initially locating the lunar slice.
Venus is visible at this hour. It is over 25° to the upper left of the thin moon.
As the sky darkens further and the stars show through the evening twilight, Venus is making its final approach to the conjunction with the crescent moon and the three stars that make the head of the Scorpion – Graffias, Dschubba, and Pi Scorpii (π Sco on the chart). The quintet appears within a binocular’s field of view in two evenings. This does not occur again until October 10, 2029.
After Venus passes Dschubba, it moves toward Antares – “the rival of Mars.” That conjunction occurs on October 16.
Jupiter and Saturn are in the south-southeast at this hour. Jupiter is the brightest “star” in the sky after Venus sets 107 minutes after sunset.
Along with dimmer Saturn to Jupiter’s upper right, both planets are retrograding in Capricornus. They restart their eastward treks this month. Notice the star Deneb Algedi – “the kid’s tail” – 1.4° to the lower left of Jupiter.
In another 90 minutes both planets are higher in the southern sky. They set in the southwestern sky after midnight.
Detailed Daily Note: Thirty minutes after sunset, the razor-thin crescent moon (1.5d, 3%) is over 4° up in the west-southwest. Use a binocular. Can you find Venus without optical aid, over 25° to the upper left of the crescent? Fifteen minutes later, Venus is over 9° up in the southwest, 2.3° to the lower right of Dschubba and 9.6° to the lower right of Antares. Farther eastward, Saturn is over 26° above the south-southeast horizon and 15.6° to the upper right of bright Jupiter. The Jovian Giant is nearly 25° up in the southeast. Two hours after sunset, Saturn is nearly 29° up in the south and a fraction of a degree east of the meridian. In the starfield, it is 1.5° to the lower right of υ Cap. Jupiter is over 31° above the south-southeast horizon, 3.6° to the lower right of μ Cap, 1.9° to the upper right of Deneb Algedi, and 1.4° to the upper left of Nashira. Mars is at conjunction with the sun at 11:01 p.m. CDT.
October 22. 2021: Speedy Mercury is low in the east before sunrise. It is putting on its best morning performance of the year. Arcturus, in the east-northeast, is about the same altitude as Mercury.
October 21-November 1, 2021: Brilliant Venus steps through Ophiuchus to the upper left of the star Antares in the southwest after sunset . Afterward, the planet steps farther eastward.
October 21, 2021: The bright moon is low in the west about an hour before sunrise. Mercury is in the east at about the same altitude as Arcturus. Venus, Saturn, and Jupiter shine from the evening sky.
December 18, 2021: This is the anticipated launch date of the James Webb Space Telescope, the largest and most sophisticated space telescope view the universe.
October 20, 2021: Mercury is brightening in the morning sky. Brilliant Venus, Jupiter, and Saturn are in the evening sky. The bright moon starts the evening low in the eastern sky.