Getting Stung By A Scorpion Can Be A Beautiful Thing

This map shows the sky facing south around 10:30 p.m. local daylight saving time in mid-July from mid-northern latitudes. Our featured objects are the scorpion's stinger stars, Shaula and Lesak, and two of summer's brightest open star clusters, M6 and M7. Map: Bob King, source: Stellarium
This map shows the sky facing south around 10:30 p.m. local daylight saving time in mid-July from mid-northern latitudes. Our featured objects are the scorpion’s stinger stars, Shaula and Lesak, and two of summer’s brightest open star clusters, M6 and M7. Map: Bob King, source: Stellarium

Near the tail end of Scorpius the scorpion you’ll find a neat pair of stars — Shaula and Lesath — that form the stinger. Dubbed the Stinger Stars, from mid-northern latitudes they never rise higher than 10°-15° or a little more than a fist above the southern horizon. Trees and buildings usually get in the way of seeing the stars, but I urge you to seek them out for two reasons.

In mythology, Scorpius represents the scorpion that stung Orion to death. Stellarium
In mythology, Scorpius represents the scorpion that stung Orion to death. Stellarium

First, you’ll get to see the full outline of the scorpion, one of the few constellations that really look like the thing they represent. The head is up at the top, followed by the animal’s “heart”, Antares, and then a long, arched tail. Pretty cool. As always, there’s more than one way to look at a star pattern. In Hawaiian constellation mythology, the scorpion is Maui’s Fish Hook. I’m sure you’ll have little trouble seeing a hook there.  It’s interesting that the Shaula-Lesak pair make up the business end in both patterns.

Once you’ve spotted the Stingers, you now have an easy way to find two of the brightest star clusters in the summer sky. Both are visible with the naked eye even from places as far north as northern Minnesota where they’re only a fist high in the sky. The brighter, M7, shines with a total brightness of magnitude +3.3 and looks like a small, misty cloud just 4.5° (three fingers held together at arm’s length) east or left of the Stingers. M7 is also known as the Ptolemy Cluster since it was first recorded by 1st-century Greek-Roman astronomer Ptolemy in 130 A.D.

A wide field view shows M7 embedded in billions of fainter stars in the disk of the Milky Way galaxy. Messier 7 gets its name from a catalog of comet look-alike objects compiled by 18th century French comet observer Charles Messier. Credit: Oliver Stein
This wide field photograph shows M7, a.k.a. the Ptolemy Cluster, embedded in millions of fainter stars near the center of the Milky Way galaxy. Messier 7 gets its name from a catalog of comet look-alike sky objects compiled by the 18th century French comet observer Charles Messier. The cluster is located about 980 light years from Earth and bright enough to easily see without optical aid. Credit: Oliver Stein

Skywatchers of ancient times, long before both the telescope and light pollution arrived on the scene, were familiar with this patch of haze but knew nothing of its true nature as a star cluster. Star clusters are gravitationally-bound groups of stars that coalesce from clouds of gas and dust. Individual stars within a cluster vary in size, but they’re all about the same age and move together around the galactic center as a group.

A pair of binoculars will transform the haziness of the Ptolemy Cluster into the glitter of individual stars. Small telescopes do even better and show about 80 bright stars in the shape of the letter K tipped on its side. It’s really an eyeful and worth the effort to see.

In this closeup view similar to what you'd see in wide-field binoculars, the two clusters really pop. Stellarium
In this closeup view similar to what you’d see in wide-field binoculars, the two clusters really pop. Stellarium

Let’s return again to Shaula but this time direct our gaze to a spot 5 (three fingers) above and slightly left or east to a second fuzzy glow called M6 also known as the Butterfly Cluster. This one is smaller and little fainter at magnitude +4.2. If you’re having difficulty seeing it, play your eye around the cluster’s location using averted vision instead of staring directly at the spot. The Butterfly was first recorded by Italian astronomer Giovanni Battista Hodierna in 1654 but it’s hard to believe it wasn’t noticed earlier. Apparently no one bothered to write it down.

It’s about half the apparent size of M7 and located about 1,600 light years from Earth. In spite of its greater distance, binoculars still show a lots of “tiny” stars packed into a space about as wide as a full moon. To see the butterfly shape, you’ll need a small telescope and low magnification. Be sure to look for the colorful orange giant star along the cluster’s east side — it stands in striking contrast to the backdrop of the cluster’s white and blue-white stars.

This telescopic view of the Butterfly Cluster shows the bright orange giant at its east (left) edge. Can you make out the butterfly? Credit: Ole Nielsen
This telescopic view of the Butterfly Cluster shows the bright orange giant at its east (left) edge. Can you make out the butterfly? The wings extend to the left and right of the cigar-shaped body. Credit: Ole Nielsen

M6 and M7 are less than 4° apart, so if you find one you can easily see the other in the same binocular field of view which typically is around 5° wide. Wider-field glass can even squeeze in the Stinger Stars. The entire region is rife with star clouds, bright nebulae and patchy dark nebulae, clouds of soot-like interstellar dust that block more distant stars from view. You can easily spend a half hour or more “sweeping” the sky with binoculars taking in the sights. Summer’s clustery richness concentrates here because we’re looking toward the center of the Milky Way galaxy, rife with all the goodies the galaxy has to offer.