2021, August 15: Moon Hits Scorpion’s Head


August 15, 2021: This evening the moon seems to hit the Scorpion’s head.  Meanwhile, the five naked-eye planets are visible leading up to the very close conjunction of Mercury and Mars.

Chart Caption – 2021, August 15: Through a binocular, the slightly gibbous moon is 4.6° to the lower right of Graffias and 4.4° to the upper right of Dschubba.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:59 a.m. CDT; Sunset, 7:50 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

The brightest planets are congregating in the evening sky. Along with the five planets, the moon appears to be banging into the head of the Scorpion.

Starting at about 25 minutes after sunset, Mercury and Mars are in the same binocular field.  Mercury is brighter than Mars, but it is only 3° above the west-northwest horizon.  Mars – at its dimmest brightness – is 3.9° to the upper left of the speedy planet.

In three evenings, Mercury passes very close to Mars.  Along with this evening’s observation, on conjunction evening, the planets are hiding in bright twilight.  This is a very challenging observation.

Venus is visible in the western sky.  Saturn and Jupiter are in the southeast. 

For the next several evenings, the five naked-eye planets are visible at about 25 minutes after sunset, although the Mercury and Mars observation is very challenging.

As the sky darkens, you cannot miss the slightly gibbous moon that appears to be smashing into the head of Scorpius the Scorpion.  The lunar orb is near Graffias and Dschubba.

Graffias is also known as Beta Scorpii.  Its name means “the crab.”  Apparently, our ancestors thought that crabs and scorpions were closely related, and they may have used the same word to name both creatures.

The star is thought to be about 600 light years away, shining with an intensity of over 2,700 suns.  The visible star has companions; it is a multiple star system.  A secondary star in the system is visible through a small telescope.  This star may have a slightly greenish tint.  Take a look.  What color do you see?

The Scorpion’s forehead, Dschubba, is below Graffias.    Like its brighter neighbor, it is around 600 light years distant and is intrinsically brighter than Graffias.

The stellar duo is part of the Scorpius-Centaurus Association, a bundle of bright blue stars that are thought to have formed at around the same time.  The stars in the association are not gravitationally bound and they are moving apart as if some galactic event sent them scattering.

Use a binocular to see the lunar orb seemingly hitting the head of the Scorpion this evening with the stars Graffias and Dschubba.

Detailed Daily Note:Approaching its solar opposition, Jupiter continues to retrograde in Aquarius near the Capricornus border.  One hour before sunrise, Jupiter is over 15° up in the southwest, 1.5° to the lower right of ι Aqr, 1.7° to the upper left of μ Cap, and 4.2° to the upper left of Deneb Algedi. The moon reaches its First Quarter phase at 10:20 a.m. CDT. Daylight is nine minutes less than 14 hours today.  Darkness – the time between the end of evening twilight and the beginning of morning twilight – is several minutes longer than 6 hours, 30 minutes.  In three evenings Mercury (m = −0.6)  passes dim Mars in a very close conjunction.  The event is very challenging as Mars is near its dimmest and the duo is low in the sky during bright twilight. (The difficulty of seeing this event is likely understated here!)  This evening, twenty-five minutes after sunset, speedy Mercury – 14° east of the sun and only 3° above the west-northwest horizon – is 3.9° to the lower right of the Red Planet. Twenty minutes later, brilliant Venus is about 8° up in the west. Continuing its eastward trek along the ecliptic, the planet – 38° east of the sun –  is 2.4° to the upper left of Zavijava and 24.4° to the lower right of Spica, that is about 15° above the west-southwest horizon.  The moon (7.5d, 55%) is near the head of the Scorpion, 4.6° to the lower right of Graffias (β Sco, m = 2.5) and and 11.9° to the upper right of Antares (α Sco, m = 1.0).  Farther eastward, Saturn is over 13° aobve the southeastern horizon.  The Ringed Wonder is 129.4° of ecliptic longitude east of Venus.  Jupiter, 18.6° of ecliptic longitude east of Saturn, is nearly 6° up in the east-southeast.  The Jovian Giant is 148.0° of ecliptic longitude east of Venus.  As midnight approaches, the Ringed Wonder, retrograding in Capricornus, is over 29° up in the south.  It is 4.9° to the lower right of θ Cap and 1.5° to the lower left of υ Cap.  At this hour Jupiter is over 30° above the south-southeast horizon.

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