Galaxies, Clusters, and more (oh my)

Galaxies, Clusters, and more (oh my)

June 21, 2022 0 By Ellen Novack

Let me start off by saying that every reader who is currently in an area experiencing severe drought should consider buying a new telescope. Because since the telescope first arrived at the end of March, there have been exactly six (6) nights in my area that were not overcast or raining. In fact, the next two months set records for rain and wind. Maybe strategic telescope purchases could put the Colorado River back on track.

And yes, that was all just a joke. Consider it result of telescope frustration.

In any case, there have been some opportunities to get out that scope, and I’m hoping for more as we roll into the generally drier months of summer. Here’s one quick example of a shot collected on one of those good, clear evenings.

Daily Space: The Hercules Globular Cluster

Hercules Globular Cluster, M13

It’s odd to think that things visible to everyone in the night sky need to be “discovered,” but it’s true. In the case of the Hercules Globular Cluster, that discoverer was Edward Halley—yes, the comet guy—who cataloged this feature of the sky in 1714 using a 24-foot-long telescope purchased for him by his pop. The Haleys were … comfortably well off. Though they weren’t exactly royalty. The elder Haley had made his fortune with a factory that produced one of the big hits of the late 17th century: scented soaps. Considering how London was reputed to reek at the time, it’s easy to understand how the tuppence added up.

With an apparent magnitude of 5.8, the Hercules Globular Cluster is just visible to those with good eyesight in good conditions. Haley may have been able to spot it more easily in those less light-polluted days. For the average person in the modern world, it helps to have a pair of binoculars and a good idea of where to point them—which is, not surprisingly, at a point in the Hercules constellation. It’s about one-third of the way between the bright stars Vega and Arcturus. You can spot it on this terrific star map at about 35 degrees, 17hr.

If you do manage to get a good pair of binoculars aimed at the right spot, you’ll see what appears to be a somewhat fuzzy “star.” What Haley saw through his relatively massive scope was only a bigger fuzzy blob. For all the size of his instrument, he had no way to record an image, so the only thing he could see was what the photons striking his eye at any moment could reveal. Halley’s view was not as good as the one above—which was produced with a scope that’s just 15” long and 1.5” across. It took another 80 years after Halley noted the position of the Hercules cluster before anyone created a telescope good enough to be sure that this was, in fact, a group of individual stars and not some kind of nebula.

In fact, the cluster contains at least several hundred thousand stars. But this isn’t a galaxy. This blob of stars is absolutely a part of the Milky Way. It’s about 22,000 light years away from Earth, which seems like a lot, but it’s much closer than the millions of light years distance to even the nearest neighboring galaxies. Clusters like this are found in almost all galaxies, but their origins remain mysterious.

Several such clusters have been identified in the Milky War. Some are distinctly colored, as the stars in the cluster tend to be of a particular age and size. But the Hercules cluster contains stars of many types, from old red giants to brand new stars blazing a brilliant blue-white. It’s a 125 lightyear-wide ball of stars, all turning around a central point, and somehow creating its own form of relative stability.

Aside from being one of the largest such clusters our galaxy contains, the Hercules Globular Cluster has another claim to fame. Back in 1974, SETI researchers decided to take a break from listening to actively send out a message from Earth. They used the ill-fated radio telescope at Arecibo to send out an encoded message that, for those clever enough to decode it, contains information about the periodic table of elements, the structure of DNA, where to locate Earth, and the basic form of humans. They aimed it at the Hercules Cluster.

If their aim was good enough (and there are debates) and someone at the other end has a radio telescope several of orders of magnitude better than anything humanity has ever constructed, they should be getting the message … in about 21,952 years.