2021, October 4: Thin Morning Moon

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October 4, 2021: Before sunrise, the razor-thin lunar crescent is low in the eastern sky.

Chart Caption – 2021, October 4: The crescent moon is low in the eastern sky before sunrise, near the haunches of Leo.

by Jeffrey L. Hunt

Chicago, Illinois: Sunrise, 6:51 a.m. CDT; Sunset, 6:27 p.m. CDT. Check local sources for sunrise and sunset times for your location.

Daily notes for October 2021

An hour before sunrise, the thin crescent moon, 5% illuminated, is over 13° above the eastern horizon. It is near the haunches of Leo. It is 5.3° to the lower right of Chertan – “the two small ribs.”

At a distance of less than 200 light years, Chertan is about 150 times brighter than our sun.

Leo is climbing into the morning sky. Its shape is easy to locate, a backwards question mark connected to a triangle. The mark is the Lion’s head and the triangle makes the haunches and tail (Denebola).

Photo Caption – 2020, November 13: The crescent moon that is 4% illuminated is in the eastern sky before sunrise. The phase is similar to this morning’s lunar crescent.

Use a binocular to see earthshine on the night portion of the moon. Reflected sunlight from Earth’s oceans, clouds, and land gently illuminates the ground in the same fashion that the bright moon shines on the terrestrial landscape.

Photographers can capture this effect with a tripod-mounted camera that can take a time exposure of several seconds.

This image from November, 2020, shows a thin crescent moon with earthshine. The moon was 4%, similar to this morning’s illumination. The camera’s characteristics: lens, 140mm; ISO, 100, time, 2.5 seconds.

The meanings of the star names in these articles are from an article in the January, 1944 issue of Popular Astronomy by George A Davis, Jr.

Detailed Daily Note: One hour before sunrise, the crescent moon (27.4d, 5%) is over 13° up in the east, 5.3° to the lower right of Chertan (θ Leo, m = 3.3) and 2.4° to the upper right of Iota Leonis (ι Leo, m =4.0). Forty-five minutes after sunset, brilliant Venus is over 9° up in the southwest, 5.6° to the lower right of Dschubba and 12.8° to the lower right of Antares. The planet continues to step eastward along the ecliptic at about 1.1° of ecliptic longitude from night to night. Farther eastward, Jupiter is nearly 24° up in the southeast, 15.7° to the lower left of Saturn. The Ringed Wonder, 26.0° up in the south-southeast, is slowing to begin its direct motion in two evenings. Two hours after sunset, the giant-planet pair is higher in the sky. Use a binocular to see the starfield with the planets. Jupiter, over one-third of the way up in the south-southeast, is 3.5° to the lower right of dim μ Cap, 1.8° to the upper right of Deneb Algedi, and 1.4° to the upper left of Nashira. Saturn, nearly 29° above the southern horizon and east of the meridian, is 1.4° to the lower right of υ Cap.

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