2021: June 20 – 23: Scorpion, Moon

Astronomy, Sky Watching
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June 20 – June 23, 2021:  The bright moon appears near the classic Scorpion.  On the first two evenings, the lunar orb appears near the pincers and on the next two, it’s near the scorpion’s heart.

Chart Caption – June 20 – June 23, 2021:  The bright moon appears near the classic Scorpion.  On the first two evenings, the lunar orb appears near the pincers and on the next two, it’s near the scorpion’s heart.

by Jeffrey L. Hunt

As the bright moon approaches its Full Moon phase (June 24), the moon moves near the Classic Scorpion, including today’s constellation Libra.

As summer opens each year, the scorpion is crawling into the southeastern sky.  Its pincers are nearing south.  Today, that stellar pair retains their original names, Zubeneschamali – “the northern claw of the scorpion” – and Zubenelgenubi – “the southern claw of the scorpion.”  Today, those stars are part of the constellation Libra.

Farther eastward, Graffias – the critter’s second brightest star – is “the crab.”  Beneath it is Dschubba – “the forehead.”

Antares, the star that could mark the scorpion’s heart, is over 15° up in the south-southeast. The star’s name means “the rival of Mars.”

The star is summer’s equivalent of Orion’s shoulder star Betelgeuse.  Both stars are distinctly rosy color to the unaided eye.  For a star, that hue indicates that its outer layers are cooler than our sun.  (Blue stars are hotter than reddish stars.  Yellow stars are lukewarm in comparison.)

Antares is the 15th brightest star in the skies of Earth and 11th brightest from the mid-northern latitudes.  Like Betelgeuse, Antares is very large – a red super giant – and intrinsically very bright.  These stars are unusual and thought to be near the end of their stellar lives. 

Betelgeuse was in the news for a few great dimming events. Was Betelgeuse about to explode into a brilliant supernova, as the press reported?  Likely not. These stars do not shine with consistent brilliance and they tend to cast off gasses.  It’s likely that Betelgeuse was tossing gas in the solar system’s direction that dimmed the star in the sky.

Because the stars have different visual intensities in our sky from their actual brightness and their distances from our solar system.  Astronomers invented a means to compare stellar properties.  How bright would the stars be if we could place them at the same distance from our solar system?  The distance is 10 parsecs – 32.6 light years.  If our sun were 10 parsecs away it would not be visible from urban and suburban locations.  Outdoor lighting would blot it out of view.

If Antares were placed at 10 parsecs, it would be brighter than Venus appears at its brightest.  While the planet shines from reflected sunshine, Antares brightness output is over 9,000 suns! 

The body of the scorpion curves beneath the horizon.  The stinger is still to be revealed.

The bright moon moves through the region on June 20 – June 23.  A binocular may be needed to see some of the dimmer stars.  One hour after sunset, here are the events:

June 20: The moon, 83% illuminated, is in the south, 6.5° to the upper right of Zubenelgenubi.

June 21:  The bright gibbous moon is nearly 30° up in the south-southeast. The lunar orb is captured in the claws of the scorpion, and it appears between Zubenelgenubi and Graffias, 8.5° to the lower left of the former star and 9.5° to the upper right of the latter star. 

June 22: The moon,96% illuminated, is over 20° up in the south-southeast, 4.1° above Antares.

June 23:  The moon, in the constellation Ophiuchus, is nearly 13° up in the southeast, over 14° to the lower left of Antares. 

Use a binocular as necessary to see the background stars with the bright moon.

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