On Parsecs, Parsnips, and Banjos
Rooted in space.
Over the last year I’ve, more by happenstance than anything else, found myself a member of a folk/bluegrass band called The Parsnip Factory. This surprising, at least to me, development has had quite a few consequences. For one, I’ve learned, not only what a parsnip is (it looks kinda like a large white carrot), but that I really like eating them. Turns out they taste great in veggie stir fry, on pizza, and even as jam on bread. For another, I’ve learned there are way more awesome instruments than you usually find in an orchestra, including washtub bass, penny whistle, and even a flamengophone.
But another surprising thing I’ve realized is the funny way that my experiences as an astronomer intertwine with even seemingly unrelated things like playing fiddle in a folk band. Sure, there are occasional songs we sing which reference the sky - like the song “Moonlight, Midnight,” say, but that’s not what I mean. Rather, it seems to be an unfortunate (or fortunate? Or neutral? - I’m still not sure) consequence of this part of my identity that conversations often involve astronomy. It’s like there’s some small-talk black hole that I orbit that if I’m not careful, we’ll have crossed its event horizon without realizing it, and soon we’ve fallen in, past the point of no return. And this has been true with The Parsnip Factory. In fact, the name Parsnip came out of a conversation about a similar sounding word - parsecs, a unit of astronomical distance. How and why we were talking about parsecs is beyond me, but there you go. It’s part of my orbit.
Sometimes the conversations aren’t even happenstance. When you’re performing a concert there’s the constant issue of what to talk about between songs. People are there for your music, not your jokes, but we usually need a little space between songs, to catch our breath, rearrange personnel, and to retune our instruments (especially, it turns out, banjos, since they get tuned differently for songs in different keys). Introducing the band members works for a while, but that only takes so much time. Then what do you talk about? I was at a concert the other day where the person assigned to fill space started talking about whether or not people were hydrating enough. “Raise your hand if you don’t drink enough water!” Ok, it’s going to be awkward, but we can do better. So at some our early concerts my ever encouraging friends asked me specifically to share some interesting and relevant astronomy facts. So I thought I’d share with you what grew out of that small challenge: some random space facts, about parsnips, folk music, and astronomy.
We might start the discussion with something like this: when you spend a lot of time below ground, you find yourself longing for some space. So here are some astronomy facts to draw on.
If you were to play a guitar or banjo on the moon you wouldn’t hear anything, because there’s no air for the sound to move through.
Now, when sound does have air to travel through, it goes pretty fast: 761 miles per hour, 1100 feet per second. You’ve probably heard that if you count to 5 between lightning and thunder you know the lightning was a mile away. But while sound is fast, it’s no match for the vast reaches of space. If it could travel through space, it would take 5 seconds for our concert to be heard a mile away, and 13 days for our concert to be heard on the moon. And 14 years to be heard on the sun! (If we wanted to make a joke about the banjo, we might add that that’s, amazingly, longer than it takes a banjo to tune.)
Before we settled on Parsnip Factory, we considered other names, some involving not parsnips, but parsecs. You may have heard of parsecs from the Kessle run, but it’s actually a real astronomy unit of distance, like a foot or a mile, but a bit bigger. And by a bit I mean quite a lot, I guess (further than you want to stay from a banjo?). A parsec is about 20 trillion miles, a distance so big it takes light 3.26 years to travel that far, which is saying something, since going the speed of light you could circle the earth 7 times in 1 second.
Interestingly, 1 parsec is the typical separation between two stars and is about the distance to the closest star besides the sun, Proxima Centauri.
Parsnips get their name from latin words for two pronged forks and digging in the ground. And parsecs actually have a pretty interesting origin too, but it’s a bit of a head twister, so hold on tight. One of the hardest things to measure in astronomy is distance - how far is it to that star? It’s not like a measuring tape will do the job. But some clever folks figured out that as the earth moves around the sun, we see stars from a slightly different angle, causing them to appear to shift back and forth a tiny tiny bit. You can see this by holding out your finger in front of you, and then closing one eye (you see your finger from one side of your head), and then switching to the other (you see your finger from the other side. Your finger will appear to move back and forth. The further you stretch out your arm, the less your finger moves, so the amount of shift ends up being a way to calculate distance. This effect has a special name: parallax. Now stars are so far away that even the closest stars shift only a tiny bit, one 3600th of a degree. Astronomers call this an arcsecond (since you are taking an arc, and you can divide it by 60 and 60 again just like you take an hour and divide by 60 and 60 again to get seconds). How far away do you have to be to only shift by 1 arcsecond when earth has gone through 1 orbit? Well, astronomers wanted a name for this distance, so they called it a parallax arcsecond, which was a mouthful. So they shortened it: parasecond? No, we can do better: parsec. And the unit stuck.
Another name we considered for the band: A Half Parsec from Home. Which got me thinking. When you’re a half parsec from home you’re just lost in space. There’s a whole lot of nothingness out there - a lot of empty unknown. A half parsec from home you’re about half way to the next star, right at the breaking point. If you go any further, you have to commit, and keep going, make a new home in an alien land. Or, right there, there’s still the possibility: you could turn around and go back home - is that where you belong? But I’ve found it’s hard to stay in between, stuck in that no-mans land of deep space: in between you get a membership of one. As far as scientists can tell, the only other thing that’s out there, besides some very diffuse cosmic dust, is the rare space snowball: primordial comets made from ice with a bit of dust floating around between the stars. These snowball comets spend their years waiting for a slight perturbance to alter their orbit, and send them on their journey to the inner solar system. It might be billions of years, but when they finally get the bump and fly close to the sun they make quite a show. You might say they come into their own. As they pass near the sun they grow giant, gorgeous, majestic tails, a sort of cosmic mist release as they are heated by the sun. These can be the most beautiful objects visible in the heavens, rare gifts for the whole world to see. How many of us are just floating, needing a little nudge to start a journey to realizing our full potential, on display for all to see? Are we all just a half parsec from home?
