2021, October 22, Mercury’s Morning Best, Arcturus


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.

Chart Caption – 2021, October 22: Mercury and Arcturus are low in the east before sunrise.


by Jeffrey L. Hunt



Chicago, Illinois:  Sunrise, 7:11 a.m. CDT; Sunset, 5:58 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Daylight continues to decline.  With daylight time, the sun sets before 6 p.m. Sunset, without daylight time, is several minutes short of 6 p.m. as the date (March 13, 2022) to advance the clock approaches.

The speedy planet Mercury is making its best morning appearance of the year.  It brightens a little every morning as it approaches its greatest separation from the sun.

During autumn mornings, the ecliptic – the solar system’s plane – is highly inclined to the eastern horizon.  Mercury stands near its highest spot above the eastern horizon before sunrise.

At 45 minutes before sunrise, Mercury is nearly 8° above the eastern horizon.  Use a binocular to find the star Porrima, 1.4° to the upper left of Mercury.

The topaz star Arcturus is about the same altitude as Mercury in the east-northeast.

During the next few mornings Mercury continues to brighten and climb a little higher in the sky. This morning the planet rises 92 minutes before sunrise.  In two mornings, it rises four minutes earlier and then slowly appears lower in the sky as it journeys into bright morning twilight.

Detailed Daily Note: An hour before sunrise, the bright moon (16.0d, 97%) is nearly one-third of the way up in the west, 12.5° below the Pleiades star cluster. Mercury (m = −0.5) is nearly 8° up in the east, 1.4° to the lower right of Porrima at 45 minutes before sunrise. If you’ve not seen Arcturus.  It is at nearly the same altitude as Mercury, about 30° to the left of the speedy planet. Forty-five minutes after sunset, brilliant Venus is nearly 11° up in the southwest, 5.3° to the lower right of θ Oph.  Farther eastward, bright Jupiter is over 28° up in the south-southeast.  Saturn, at nearly the same altitude as Jupiter, is 15.3° to the right of the Jovian Giant.  Two hours after sunset, the bright moon (16.6d, 95%) is over 7° above the east-northeast horizon and 6.1° to the lower right of the Pleiades star cluster.  Jupiter and Saturn are in the southeast, each on opposite sides of the meridian. Jupiter, nearly 33° up in the sky, is 3.8° to the lower right of μ Cap, 2.0° to the upper right of Deneb Algedi, and 2.0° above Nashira.  Saturn, west of the meridian, is over 28° up in the sky, 1.4° to the lower right of υ Cap.  Use a binocular to see the stars with the planets. Venus sets 126 minutes after sunset.



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