Great Globular Cluster in space is sight to behold


By Tom Burns - Stargazing



Straight overhead in the early evenings of July is the constellation Hercules. Unfortunately, in July, “early evenings” means after 10:30 p.m.

Legends about his exploits go back farther than history records. Even before the ancient Greeks, he was seen as the “kneeling man” in many cultures. As he kneels, he places his left foot on the head of the giant serpent Draco, who stretches below him in the northern sky.

He represented for the ancient Greeks and Romans the highest ideals of bravery and headstrong heroism.

Hercules has the privilege of containing the Great Globular Star Cluster, the most beautiful astronomical object in the skies of the northern hemisphere.

To find it, you must first find the constellation. After evening twilight, look high in the eastern sky for the very bright star Vega. West of Vega, almost straight overhead, is a large, rough square of stars called the Keystone. It makes up the trunk of Hercules’ body. His upraised arms stretch south, and his legs are to the north.

Find the two stars on the west side of the Keystone. About one-third of the way up from the north-most star, you will see a small, fuzzy, round patch in binoculars, marked as M13 on most star charts.

M13 must have been easily visible to the ancients without optical aid because, even with today’s light pollution, it is visible to the naked eye from dark, rural sites.

M13 was something of a holy grail to me during my youth.

After many tries, I finally found the danged thing in my old man’s pair of $3 opera glasses. I wanted so much to see it in all its glory.

Thus, I stared forlornly at the telescope ads that appeared in the back of magazines like Popular Science, my chief source of astronomical knowledge. They were way beyond the means of my working-class family.

When my parents finally bought me a “telescope” one Christmas, I discovered to my disappointment that its mounting was too cheap to stay pointed even at the moon. When I finally got it very briefly to stay steady on some random star, I couldn’t get that pile of junk to focus to a point of light.

My old man wanted to encourage my interest in astronomy, so he bought a copy of Edmund Scientific’s All About Telescopes with the intention of building one. We bought a kit to grind and polish a six-inch diameter mirror, but the effort never got past the initial stages. Neither one of us was up to the drawn-out and intellectually demanding task of creating a mirror from scratch.

When I finally got to graduate school, I had a few bucks to spend. Ohio State’s English Department was paying me a meager sum to teach a few sections of their Freshman Composition course.

I still couldn’t afford the telescope on the back of Popular Science.

However, I managed to save enough after many months to purchase a commercially made set of telescope mirrors. The telescope’s mount was created out of scraps of plywood and painted hastily with leftover blue house paint. Such was my ardor to see M13 and all of the other wonders of the universe.

My initial efforts from my backyard in Clintonville were failures. Light pollution and my painful inexperience with telescopes convinced me that I needed help.

I had heard that the members of the local astronomy club often set up telescopes at Perkins Observatory on clear nights. So one fine night, I drove tentatively up the long driveway to Perkins.

“Turn off your (expletive removed) car lights,” a chorus of voices yelled. I knew that I had come to the right place.

With some help from a member of the club, I finally saw M13 in all its glory, and I will never forget that first look.

I was looking at more than a quarter of a million stars in one telescope field. M13 is an explosion of starlight so dense that it is difficult to resolve the stars into individual points of light except in a large telescope.

Globular clusters like M13 are composed of very old stars that are very close together. At about 22,000 light years away, M13 is about as far away as an astronomical object can get and still be in our Milky Way galaxy.

“Globulars” are clusters of stars that huddle around the dense galactic core but outside the disk of the galaxy, out in the galactic suburbs, you might say. M13 is perhaps 100 light years, or 600 trillion miles, in diameter.

Words fail me here as they failed me then. In a telescope, M13 looks like a globe of stars, dense with countless points of light at the center and slowly becoming sparser as you move outward. It looks like a giant swarm of fireflies or a pile of diamond dust. I saw so many stars that it was impossible to count them.

Its home constellation Hercules had the misfortune of being born out of the dalliance of Zeus, the king of the gods, and a mortal woman named Alcmene.

Zeus’ wife, Hera, was extremely jealous of Zeus’ many mortal lovers, but she couldn’t do much to get revenge against her more powerful husband.

So she took it out on the mortals. Hera had had a grudge against Hercules ever since he was born, and Hercules had to face her considerable wrath for most of his life.

Like the other gods, Hercules had a considerable temper and a great appetite for adventure.

The night sky is littered with the carcasses of the great beasts that Hercules killed during his eventful, heroic life.

His bloody presence is felt all over the sky. Among his famous Twelve Labors, he killed the Lernean Hydra, visible as a long string of stars low in the southern spring sky. He also killed the Nemean Lion, which is said to be the constellation Leo, now setting in the western sky. Just below Leo in the southern sky is Cancer, the giant crab, slain by Hercules as he battled the Hydra.

The Crab, the Lion, and the Hydra were the nasty household pets of Hera, wife of Zeus and queen of the gods. She sent them to bedevil humanity in general and Hercules in specific. He always managed to triumph, but Hera managed to make his life unpleasant until the end.

However, at that end, the gods respected Hercules’ headstrong bravery and suffering so much that they took him up into the heavens to dwell with them when he died. There he made his peace with Hera and married her daughter, Hebe.

If I were to add to the myth (and why not?), this is what I would say: The gods so loved him that they placed upon his chest the Great Globular Cluster, 250,000 suns — a glorious badge of honor.

When I was offered the job as Director of Perkins Observatory 25 years ago, my mind and heart traveled to that moment when I saw M13 in all its glory for the first time and to the CAS member who helped me find it. I was as if I had been offered Hercules’ badge, but I firmly believe that I would never have had the chance to wear it had it not been for that CAS member.

I vowed that I would preserve Perkins for its historical value, for its usefulness to Ohio Wesleyan, and for its importance to public education in astronomy. But most of all, I vowed that I would preserve Perkins for that CAS member who helped me find M13. I would preserve it for all those who came after him. I would preserve it so that all those who value the beauty of the stars would, quite simply, have a place to go.

Even in retirement, I will not abandon that mission.

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By Tom Burns

Stargazing

Tom Burns is director of the Perkins Observatory in Delaware.

Tom Burns is director of the Perkins Observatory in Delaware.