On Nov. 16, 1974, astronomers sent skyward a cryptic three-minute radio signal from the newly dedicated radio telescope with a 1,000-foot diameter in Arecibo, Puerto Rico. It carried into the heavens the story of our world, our species and our understanding of the cosmos.
The signal was sent in the direction of the constellation Hercules, toward a giant globular star cluster known by the less-than-poetic name of M13. They chose M13 because among the cluster’s hundreds of thousands of stars might exist at least some planets where technologically advanced life could exist.
Today, however — more than four decades later — no one is sitting around awaiting a response, for, you see, even traveling at the remarkable speed of light (186,282 miles per second), the signal has journeyed little more than one-thousandth of the way toward its destination. If someone or something should receive and decipher it, a reply would take another 250 centuries to reach us.
It’s not a particularly lively conversation, but that’s OK. No one ever expected a reply. The signal was intended only as a message in a bottle, tossed by the human race to the cosmic sea.
In essence, it said, “We’re here.” And, while we may never know its fate, this message might one day let other beings curious about their own uniqueness know that they are not alone.
It’s all a pretty remarkable concept, if you ask me. And equally remarkable is that we can see this very star cluster with our own eyes on any clear dark night if we know just where to look.
During early May, gaze low in the northeast sky after dark to find the Keystone of Hercules about midway between the bright star Vega and the tiny arc of stars known as Corona Borealis.
From a dark-sky site with no moonlight, identify the Keystone and look about one-third of the way between the most northwestern and the most southwestern stars for a faint fuzzy patch of light.
You may not see it at first, so try a trick used frequently by astronomers. Instead of staring directly at this spot, look slightly off to its side. When not looking directly at it, you should see its hazy light more easily.
If you can’t spot it with your eyes alone, aim binoculars in its direction and you’ll have little trouble picking it up.
This seemingly insignificant smudge is one of a hundred or so globular star clusters known throughout our Milky Way galaxy. These contain hundreds of thousands of relatively old stars bound together by gravitation, the same force that holds us to the Earth.
Although M13 is barely visible to the unaided eye on a clear dark night, aim a small telescope toward it and you’ll be stunned by the thousands of stars you can see within its spherical form. You will surely exclaim, “It’s full of stars!”
And, if there are alien stargazers living in M13, imagine what they might see in their sky. The stars would appear hundreds of times more concentrated than in the best skies above Earth, and nighttime would be an exceedingly rare and bone-chilling experience.
Click here to learn more about the Arecibo message from Wikipedia.
— Dennis Mammana is an astronomy writer, author, lecturer and photographer working from under the clear dark skies of the Anza-Borrego Desert in the San Diego County backcountry. Contact him at mammana@skyscapes.com and follow him on Twitter: @dennismammana. Click here to read previous columns. The opinions expressed are his own.