The large globular cluster in Hercules

The Great Six-Tailed Comet of 1744
Illustration showing the six tails of a comet in the pre-dawn sky

There are comets, and then there are big comets. Surely it was the fire that broke out in the sky in 1743 and 1744 one of the newest.

When the comet was passing through Earth towards the sun, the comet was bright enough to be seen in daylight and it overtook Venus in the night sky. It has also developed a long and clearly visible double tail, which is already unusual. Then, when it reached perihelion and revolved around the sun, the comet’s tail split into six clearly defined rays. In the morning, when the comet’s head was still hidden on the horizon, these six tails were bright and visible, reaching the sky like a kind of “fan” that seemed to come from the sun.

Why the comet gave this appearance remains a mystery. In fact, there may be one or two much wider tails, but there were areas that were darkened by the thick dust. Either way, it has been recorded by astronomers all over the world, including in China, where court astronomers claimed the comet made a crackling noise. This was a very strange sin.

The not-great young Catherine noticed the culprit while traveling to Russia to get married. Apparently, she thought about declaring her future greatness because… of course she did.

Back in France, the young Messier also seems to have seen the comet and seems to have come a long way in propelling it towards a future in astronomy rather than the decidedly wonderful career of taking people to court. Messier got a job as assistant to Joseph Nicolas Deliel, who was the official astronomer in the French Navy (designing a course, etc.) and perhaps most importantly, the dirty rich.

Delile had a newly built observatory, and young Messier quickly settled in. Over the next decade, he made a number of important discoveries, receiving a senior government post as well as a number of honors and membership in the scientific community. As expected, comets remained a subject of special interest to Messier, and he seemed to be good at getting rid of a distant comet before other astronomers could put their names to the oncoming snowball. Even King Louis XV gave Messier a very impressive nickname which is ” Mongoose Comets” which, if you have a title engraved on your headstone, should be the title.

But Messier’s later work with deep-sky objects is best remembered today. Beginning in 1771, Messier began compiling a catalog of some of these misty spots in the night sky – things we know today as nebulae, galaxies and star clusters. The first list included 45 of these items. The final list, which included some things taken from Messier’s footnotes and marginals, totaled 110. These became known as miserable beings.

Since then, finding these Messier objects has been a right of passage for astronomers. Something like climbing the Seven Summits in mountaineering. Except for a much lower chance of dying in an avalanche.

And… well, it turns out that Messier 13 is something that is known as the Hercules Star Cluster, the Hercules Great Globular Cluster, or the Hercules Globular Cluster. Messier was not the first to discover the M13. This credit goes to another comet man, Edmund Halley, who found it in 1714. But Messier put it in the catalogue,

M13 is a group of hundreds of thousands of stars, but it is not a galaxy. In fact, it’s one of many bubbles orbiting our good old galaxy, the Milky Way. It is located about 22,500 light-years from Earth. If you want to find it, look where the name suggests – in the constellation of Hercules. But bring a telescope. Despite the number of stars in this group, their visible size is over 11, and they are too faint to be seen with the naked eye.

M13 is about 100 times more densely filled with stars than neighboring regions around Earth. There are only about 135 stars within 50 light years of Earth. It’s interesting to think about what a sky as big as a nearby neighbor might look like on a clear night. The stars in M13 are closer enough than ever before, and then one pair ends up merging into a short-lived blue-white giant.

Something about the M13 has made the spherical cluster of Hercules a recurring theme in science fiction novels. That may be why, in 1974, when SETI personnel at the missing but not forgotten Arecibo telescope were looking for a target for a test message, they chose M13. Somewhere between here and there, a letter with basic math information, and then it expands on that to describe the structure of atoms, then the elements, then DNA, and then some basic facts about human life.

If someone is out there and they have a very good receiver, they will have correspondence in about 22,450 years.

As with most of the images I show in this resource, the top image was taken on the small but smart Vespera telescope. And as usual with this feature, I hope some of you do much better. But maybe it doesn’t get any better than that…

Image from the Hubble telescope M13.

web countdown: “NASA, in partnership with the European Space Agency and the Canadian Space Agency, will release the first color images and spectroscopy data to the James Webb Space Telescope during a televised broadcast beginning at 10:30 am ET on Tuesday, July 12. ” And we’re going to cover it live.

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