I was a science fiction reader before I dipped my toe into the vast ocean of romance. More than that, I like space opera. Yes, I’m a Star Wars fan, despite the rather ordinary science. What attracts me is the aliens and the space ships and the amazing different worlds out there. And after all, with current estimates for the number of habitable worlds in the Milky Way – those with liquid water – at up to five billion (5,000,000,000) (New Scientist Nov 2020), why not?
Although my Ptorix Empire series and Morgan Selwood series are set in an indeterminate part of some galaxy somewhere, when I decided to write stories for the Dryden franchise, I wanted somewhere real in our very own Milky Way. I needed an environment where a Human Empire has been able to develop. That required very good communication and rapid interstellar travel – a bit like you’d find in Star Wars, where hyperspace travel is a bit like catching the local bus. Even so, distances in space are enormous, so I wanted a region of real space where the planets were closer together so that a cohesive Empire could form.
Accordingly, I did some homework on star clusters. Globular clusters, it seemed, were not the best fit. The stars are very old first generation (that is, formed not long after the Big Bang), and gravitationally bound to each other. Current knowledge suggests that mitigates against planetary systems, both because of the forces, and also because the material from which planets (and we humans) are formed comes from supernova debris, and these clusters are poor in such material, since not enough time had passed for suns to age and explode. Which does not mean planets do not exist in globular clusters, as this article from NASA attests, just that they are unlikely to support life as we know it.
However, open clusters are very different. The stars are younger, without being too young for planetary systems to have formed. They form in the usual stellar nurseries like the gas and dust clouds of the mighty Orion Nebula. From there, they remain in a more ‘open’ gravitational relationship until they leave home on their own. Our sun was probably part of an open cluster when it was a teenager. You can find out more about open clusters here.
After searching online information about known open clusters, I eventually zeroed in on M24. According to the article in the Messier objects website, M24 is in the constellation Sagittarius and it’s pretty big – ten to sixteen thousand light years across. There are thousands and thousands and thousands of stars in there, relatively close together, so it seems to be an ideal place for an author to set up a civilization. Yay me.
I’d written a few stories for my Dryden Universe before I discovered that science had moved on and astronomers have established that M24 isn’t any sort of cluster. It’s a kind of window, a rare area of sky where the view is not obscured by interstellar gas and dust, so the viewer can see the profusion of stars. It’s like seeing the sky through a hole in the clouds. This 8 minute video explains it better than I could (well worth a watch if you like astronomy).
So my Dryden Universe books are set in somewhere a lot like the previous understanding of M24. It’s fiction, after all.
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