Astro Bob: Meet Scorpius, Minnesota's only indigenous scorpion
Get acquainted with the arachnid that did in Orion.
DULUTH — Here in Minnesota there are no indigenous scorpions, but you don't have to look far to find them. Several species reside in neighboring states North and South Dakota. Our only scorpion-of-a-sort is a harmless celestial lookalike called Scorpius. Like the living version it's largely nocturnal. Every clear July night, you'll find it crawling slowly across the bottom half of the southern sky.
Scorpius is a very ancient constellation. Before adoption by the Greeks and Romans, the Sumerians pictured GIR-TAB the scorpion here more than 5,000 years ago. With a curving tail poised to sting it's one of the few star groups that looks like the real animal. Some people call it "Scorpio," but the proper astronomical name is Scorpius. The term Scorpio is now used only in astrological circles.
In the Greek myth, Scorpius was sent to sting and kill Orion for either his personal indiscretions or bragging that he could kill any animal on Earth he wished. After a pitched battle, the scorpion administered its fatal sting to the boastful hunter. In an interesting twist, the two constellations lie in opposite parts of the sky. As the vanquished Orion sets in the west in spring, Scorpius the victor rises in the east.
I'm guessing that like me you probably only see the top half of the constellation from your home or apartment. For observers in mid-northern latitudes the tail and stinger drag along the bottom of the southern sky near the horizon. The farther south you live the higher Scorpius climbs and the easier it is to see the entire figure. Looking straight south at eye level, the constellation's brightest star Antares stares me right in the face. Above and to its right are three stars in a slanted, near-vertical line that recalls Orion's Belt and outlines the scorpion's head.
From a location with an unobstructed view to the south you'll see most or all of the tail which terminates at Shaula, the Stinger Star. Antares is your touchstone star — find it and you can connect-the-dots to see the entire constellation.
Like better known Betelgeuse in Orion, Antares is a massive red supergiant star that will likely blow itself to smithereens in a supernova explosion once its nuclear fuel supply is exhausted. One of the largest stars visible with the naked eye, it's 700 times the diameter of the sun. If put in its place, the supergiant would engulf all the inner planets out to and beyond Mars.
There are several fine binoculars sights within the scorpion's lair including the globular cluster M4, located just 1.3° to the lower right (southwest) of Antares. It looks like a fuzzy star, but a telescope will chop it up into hundreds of pinpoint suns.
Two additional open (looser) clusters — M6 and M7 — float about 5° above and left of the tail. These groups are brighter and more spread out, so you'll be able to discern individual stars or at least a general "twinkliness" in both. They are two of the finest binocular objects in the summer sky.
So go ahead. Feel free to explore this storied arachnid the next clear night. You have nothing to fear.