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2021, October 21, Bright Morning Moon, Mercury, Evening Planet Pack

Moon in Gemini, December 3, 2020

2020, December 3: One hour before sunrise, the bright gibbous moon is over 30° in altitude in the west. It is near central Gemini beneath the Twins, Castor and Pollux.

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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.

Chart Caption – 2021, October 21: The bright moon is low in the west before sunrise, near the brightest stars of Aries.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:10 a.m. CDT; Sunset, 6:00 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Morning Sky

About an hour before sunrise, the bright moon, 99% illuminated, shines from low in the western sky.  It is in front of the stars of Aries, near the Cetus border.  Two of the brighter stars of the Ram, Hamal and Sheratan, are to the upper right of the lunar orb.  Hamal – “the full grown lamb” – is over 12° to the upper right of the moon.  The star is less than 70 light years away and shines with a brightness of about 100 suns.

Sheratan – “the two signs” – is about the same distance as Hamal and about 50 times brighter than the sun.  It 3.9° to the lower left of the constellation’s brightest star.

Merkar – “the nostril” – is in the constellation Cetus, the Sea Monster.  This star is to the upper left of the lunar orb at about the same separation as Hamal.

To see these stars, it is necessary to block the moon’s brightness with your hand as you would to shield your eyes from the sun or step into the shadow of a building so the moon is blocked and these stars are visible.

Chart Caption – 2021, October 21: Mercury and Arcturus are low in the eastern sky before sunrise.

About 15 minutes later, look for Mercury about 8° up in the east.  Use a binocular to spot the star Porrima, 1.3° to the upper left of the speedy planet.  Mercury continues to brighten each morning.  At this hour, look for Arcturus, about 30° to the left of Mercury.

Evening Sky

The evening planet pack, brilliant evening Star Venus, Saturn, and Jupiter, are easily spotted after sunset.

Chart Caption – 2021, October 21: Venus is in the southwest after sunset, to the upper left of Antares.

Venus, in the southwest, steps into Ophiuchus this evening.  It moves eastward through the constellation for the next 11 evenings.  Watch it move relative to Theta Ophiuchi (θ Oph on the chart).  This evening the brilliant planet is 6.3° to the lower right of the star and 5.6° to the upper left of Antares.

Venus sets 124 minutes after sunset.

Chart Caption – 2021, October 21: Bright Jupiter and Saturn are in the southeastern sky after sunset.

Bright Jupiter and Saturn are in the southeastern sky.  After Venus disappears below the horizon, Jupiter is the brightest “star” in the sky.  Saturn is over 15° to the right of the Jovian Giant. 

Both planets are gently moving eastward compared to the stars of Capricornus.  Note that Jupiter is 2.0° to the upper right of Deneb Algedi – “the kid’s tail.”

Venus moves eastward faster than Jupiter and Saturn.  This evening Saturn is over 52° east of Venus.  As Venus quickly steps eastward, it cuts the distance to Saturn to about 24° in a month.

It seems as though an evening conjunction with Saturn might occur.  However, Venus’ appearance in the evening sky seems to stall.  Later in the year, Venus retreats back toward bright sunlight.  A conjunction occurs on March 29 in the morning sky after both planets pass their conjunctions with the sun.  The year 2022 has a dance of planets in the morning sky with six planetary conjunctions that involve Venus during the first half of the year.

Detailed Daily Note: One hour before sunrise, the bright moon (150d, 99%) is nearly 20° up in the west, 12.4° to the lower left of Hamal (α Ari, m = 2.0), Fifteen minutes later, Mercury (m = −0.3) is nearly 8° up in the east, 1.3° to the lower right of Porrima.  Use a binocular.  Forty-five minutes after sunset, brilliant Venus (m = −4.5) is nearly 11° above the southwest horizon.  This evening the planet moves into Ophiuchus, 4.6° to the upper left of τ Sco.  Notice that Venus is nearly midway from Antares to Theta Ophiuchi (θ Oph, m =3.2).  Farther eastward, Saturn is over 28° up in the south-southeast.  Jupiter is 15.3° to the left of Saturn.  Two hours after sunset, the moon (15.6d, 98%) is nearly 13° up in the east.  Jupiter and Saturn are in the south.  The meridian divides them.  Saturn is west of the celestial divider, while Jupiter is east.  Saturn is 1.4° to the lower right of υ Cap.  Jupiter is 3.8° to the lower right of μ Cap, 2.0° to the upper right of Deneb Algedi, and 1.4° to the upper right of Nashira.  Both planets are gently moving eastward compared to the starry background.  While Jupiter is picking up apparent eastward speed, Saturn continues to narrow the gap between them.  The closest separation occurs in three evenings.

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