October 17, 2012
Caution: Narratives Being Built
When I was younger, I was (you’ll be shocked by this, I’m sure) fascinated by space. I learned about the planets and their orbits and their names and their colors (and I learned that there were nine of them—oops). Among my prized collection of space-themed t-shirts was one from the Adler Planetarium in Chicago, which depicted the planets in their orbit around the sun. I loved looking at that shirt and picturing the planets as they moved throughout their orbits. And I learned about distant stars and how they worked and what the constellations were.
Now. Learning about the gasses that make up the atmosphere of Venus (hint: if you are ever on Venus, BRING AIR) is pretty cut and dried; it is objective. Learning that it’s called Venus and that it’s a planet is somewhat less so (especially now that there is now some actual controversy over what, exactly, is and isn’t a planet). But it’s a discussion grounded in fact, where the disputes are largely about how we express the reality, not the underlying reality.
Constellations, however? Constellations are not intrinsic to the stars themselves. Let’s take the Big Dipper. Of course, it doesn’t have to be called that—in Hindu astronomy, for instance, it’s called the “Seven Great Sages,” after influential figures in the Vedas. In Hungary, it’s called the Göncölszekér and is thought not to be any kind of a spoon but in fact a mythical cart. It is mentioned in the Bible and Homer’s Iliad.
What’s fascinating is that in so many cultures, those seven stars have taken on a special meaning, even as that meaning varies between time and place. But the grouping of those seven stars together has far less to do with them and much more to do with us. The closest of the stars, Mizar, is 78 light years away; the most distant is Dubhe, at 124 light years away. That’s a difference of 46 light years. To put that into some perspective, the closest star to Earth other than our sun is Proxima Centauri, which is roughly four and a quarter light years away. Proxima Centauri, it should be noted, was not discovered until 1915—it requires a telescope to even see it. The stars comprising the Big Dipper are of course much brighter (we can see them even from here), but if we were standing on a planet in orbit around Mizar, there’s nothing to suggest that we would realize that we had any sort of a kinship with Dubhe; it might very well appear to us as just another star in the sky.
Constellations appear because there are many stars in the sky, and because our brains are wired to seek patterns and to impose them upon what we see. Once we’ve named the Big Dipper, it’s obvious that those seven stars out of the thousands in the night sky are significant. But that’s an imposition we’re making on the sky.
Just how many stars are there? Well, that depends on a lot of factors: