2021, October 26:  Speedy Mercury’s Morning Best


October 26, 2021: Mercury is at its greatest morning appearance for the year.  Look low in the east-southeast before sunrise.

Chart Caption – 2021, October 26: Look for Mercury about 45 minutes before sunrise. The star Arcturus is nearly 30° to the left of the planet.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:16 a.m. CDT; Sunset, 5:52 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Planet Mercury is making its best morning appearance for the year. The planet is bright, but it is low in the eastern sky.  Locate a clear horizon toward the east-southeast.

The solar system’s plane is tilted favorably for sky watchers in the northern hemisphere to see the planet when it swings from the sun’s glare during the autumn months, appearing low in the sky.

Beginning 45 minutes before sunrise, the planet is over 8° up in the sky.  It is a bright “star.”  That’s the best show it can provide.

Notice the star Arcturus, low in the east-northeast, is a little higher than Mercury and about 30° to the left of the planet. 

If you take along a binocular, note the star Porrima, 4.6° to the upper right of Mercury.

The planet continues to brighten, but it appears lower in the sky as it dips toward bright twilight.  This morning, the planet rises 95 minutes before sunrise.  By the beginning of November, Mercury rise occurs 85 minutes before sunrise.  Each day thereafter, it rises two to three minutes earlier each morning.

Detailed Daily Note: Mercury is at its greatest morning elongation (18.4°) at 12:30 a.m. CDT. One hour before sunrise, the moon (20.0d, 72%) – over two-thirds of the way up in the sky above the southwest horizon – is 3.4° to the right of Mebsuta (ε Gem, m = 3.0). Fifteen minutes later, Mercury (m = −0.8) is over 8° up in the eastsoutheast, 4.6° to the lower left of Porrima. Forty-five minutes after sunset, Venus is over 11° up in the southwest, 2.2° below θ Oph. Farther eastward, bright Jupiter is over 29° up in the south-southeast.  Saturn is 15.3° to the right of the Jovian Giant.  Two hours after sunset, Jupiter – over 33° up in the south and east of the meridian – is 3.7° to the lower right of μ Cap, 2.0° to the upper right of Deneb Algedi, and 1.4° above Nashira.  Saturn, over 28° above the southern horizon and west of the meridian, is 1.3° to the lower right of υ Cap.  As midnight approaches, the moon (20.7d, 65%), over 17° above the east-northeast horizon – is 7.3° to the upper right of Pollux.  At this hour, Jupiter is nearly 15° above the southwest horizon.

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