Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:
ULTIMA THULE
It just so happens that the New Horizons space probe, which flew by Pluto in 2015, will pass near another Kuiper Belt Object at the start of 2019—on New Year’s Day, in fact! And that Kuiper Belt Object is called Ultima Thule (pronounced thoo-lee).
I first heard this name on a podcast called Are We There Yet? (click here, it’s about 20 minutes long), and I was initially confused. I had thought New Horizons was heading toward an object named MU69; what the heck in an Ultima Thule? Turns out they’re one in the same. “(486958) 2014 MU69” is the official name approved by our old friends, the International Astronomy Union (I.A.U.), but NASA recently held a contest to see if the public could come up with something better.
The New Horizons mission team selected “Ultima Thule” as the winner, making it the official unofficial name, if that makes sense. And it’s a good name, a name with a long history going back to medieval times. Thule was the name for a mythical island that was said to be as far north as you could possibly go, somewhere right at the edge of the world as Mankind knew it. So Ultima Thule was an even more mythical land somewhere beyond that, beyond the limits of the known world!
The metaphor, I think, is that Pluto is Thule: the most distant planet (sort of) in the Solar System, and now we’re going to a place even farther than that. Ultima Thule will be the most distant object ever visited by one of our space probes, and it will stretch the boundaries of human knowledge. So yeah, the name seems appropriate.
But it’s interesting to me that NASA and the New Horizons mission seem to have picked this name without consulting with the I.A.U. first. They’ve done this sort of thing before, assigning a whole bunch of names to surface features on Pluto, and putting those names into official, scientific documents without asking for the I.A.U.’s permission first. This reportedly annoyed the I.A.U. And some of the scientists from New Horizons are still fighting to get Pluto’s planet status back, which I’m sure also annoys the I.A.U.
According to this press release from NASA, the New Horizons mission will submit an official naming proposal to the I.A.U. after the New Year’s Day flyby, once they know exactly what it is they’re naming. I’m guessing the I.A.U. will accept Ultima Thule, but if there does end up being a bit of a spat over this between the I.A.U. and New Horizons team, it wouldn’t surprise me.
Correction: I spent much of New Year’s Eve watching NASA TV, and everyone there pronounced the name as Ultima Too-lee rather than Thoo-lee. So I guess that’s how you say it.
Planet Pailly 
It is great knowing the origin of the name. Also thanks for the pronunciation guide. I’ve had been saying it wrong until now. It should be an amazing flyby. Sometimes we don’t give NASA enough credit. Your posts are always interesting and informative.
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Thanks! NASA’s press release included a pronunciation guide too, so I figured it would be helpful. If my first exposure to the name hadn’t been in a podcast, where someone was saying it out loud, I’m sure I would’ve said it wrong too. There have been a lot of these terms that I read about, and even wrote posts about, only to find out later that I’d been saying them wrong.
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Well according to Harvard Astronomers Pluto is a planet again. Others say forget about it. We’ve got the 3rd IAU rule which dictates pluto lovers must show how it regulates itself, gravity right? which it doesn’t. So how it moves caught up in an asteroid belt…. well now its just one of the rocks hurtling around, I guess lol.
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I hadn’t heard about the Harvard astronomers, but the definition of planet is far from settled. I’m a big fan of a geophysical definition, which would make “planetness” intrinsic to the object, regardless of where its orbit happens to take it. This would make the Moon a planet as well, but honestly that doesn’t bother me much.
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My first recollection of the name Ultima Thule was in a first season episode of Space:1999, wherein the Alphans passed a human outpost on Ultima Thule, and some of them considered abandoning Alpha and staying… until they discovered the weird aging effect going on there. (Interestingly, it would have made them immortal if they’d stayed.) I learned of the real history of UT much later.
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It’s been such a long time since I’ve seen Space: 1999. That was a really good show. And I guess they knew what they were talking, at least as far as using that name for something.
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My first recollection of the name Ultima Thule was in a first season episode of Space:1999, wherein the Alphans passed a human outpost on Ultima Thule, and some of them considered abandoning Alpha and staying… until they discovered the weird aging effect going on there. (Interestingly, it would have made them immortal if they’d stayed.) I learned of the real history of UT much later.
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