New Horizons: The Road Goes Ever On

The New Horizons mission has been on my mind recently, in part because of my post last week on Ultima Thule, but also because I just started reading Chasing New Horizons: Inside the Epic First Mission to Pluto by Alan Stern and David Grinspoon.

New Horizons has already visited the most distant “planet” in the Solar System (Pluto was still considered a planet when New Horizons launched), and now it’s going to explore an object even more distant than that. And after that?  Onwards to interstellar space, just like Voyager I and Voyager II, to continue exploring the universe for us.

But as I said, all this has got me thinking about travel and exploration and discovery, and also strangely (or perhaps not so strangely) about J.R.R. Tolkien.  So today I’d like to share a piece of Tolkien’s poetry, something that fit nicely into The Lord of the Rings but also fits nicely (I think) into the ongoing saga of the New Horizons mission.

Sciency Words: Ultima Thule

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:


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.