By Dr. Ed Albin
Program Director, Space Studies, American Military University
Taken on the evening of September 10 this year, this week’s image features the Great Hercules Star Cluster. I used the university’s 24-inch telescope to acquire this image for my computer in Atlanta, Georgia, keeping in mind that our observatory is on the main campus in Charles Town, West Virginia.
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This beautiful spherical cluster of stars, classified by astronomers as a globular star cluster, consists of well over 100,000 distant suns. These stars were some of the first to form in our Milky Way galaxy some 13 billion years ago. They are the oldest stars in our galaxy.
The Great Hercules Star Cluster’s swarm of stars extends across 145 light-years. Situated 25,000 light-years away from Earth, it’s humbling to keep in mind that light travels at such a speed that it can reach the Moon in less than two seconds.
Edmund Halley: The First Astronomer to Discover the Great Hercules Star Cluster
Although it was not until 1714 that famed English astronomer, Edmund Halley, first discovered the Great Hercules Star Cluster, observers of antiquity could just make out the stellar grouping with their naked eyes as a fuzzy smudge of light on clear, moonless nights. You can find this cluster by drawing a line between two of the brightest stars of summer, Deneb and Vega, and then by extending a line pointing toward the east, approximately the same distance between these brilliant stars.
Stargazers call this part of the sky the constellation of Hercules. Named after the mythological strongman and Greek hero, the Hercules stellar pattern looks like a lopsided keystone of four faint stars. It is between the easternmost pair of these stars that we find the Great Hercules Star Cluster.
Charles Messier Added This Cluster to His ‘Deep Sky’ Catalog
In 1764, French astronomer Charles Messier noted the Great Hercules Star Cluster in his famous “deep sky” catalog. Objects like this cluster are celestial beauties found beyond our solar system, and they are named in honor of the French astronomer to this day — Messier Objects.
Messier’s catalog has over 100 such interesting objects that are the very best targets for telescopic observers, both amateur and professional. Given the designation M13 in Messier’s catalog, the Great Hercules Star Cluster is one of the finest globular clusters in the entire sky.
The Great Hercules Star Cluster Is Also the Target of a Message from Earth
The Great Hercules Star Cluster also has the distinction being the target of the renowned 1974 Arecibo message, a message beamed from Earth to the stars. Sent from a radio telescope in Puerto Rico (the world’s largest telescope at the time), this powerful signal consisting of “Hello from Earth” greetings, is one of the few times our species has attempted to communicate with the stars.
As this message makes its way to the distant cluster of suns in the Hercules constellation, we can only speculate on who — or what — might receive our good wishes in the year 26,974. For now, we can only ponder at the beauty and wonder of this distant cluster of stars through our modest telescopes.
About the Author
Dr. Ed Albin is an Associate Professor and Program Director of Space Studies in the School of STEM (Science, Technology, Engineering and Math) at American Military University. His academic credentials include a Ph.D. in Planetary Geology from the University of Georgia, an M.S. in Geology from Arizona State University and a B.S. in Earth Science from Columbus State University. Ed has also held positions as an assistant professor, a planetarium lecturer, a commercial helicopter pilot and a planetary geologist.