Lucy, Dinkinesh, Trojans, and the naming of names

March 9, 2023 Issue #536

The edge-on disk galaxy NGC 5866. Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA); W. Keel (University of Alabama, Tuscaloosa)

SciAm What SciAm

Stuff I’ve written for Scientific American

Yesterday (Wednesday, March 8, 2023) I had a new article published in Scientific American. It’s about NASA’s Lucy mission to visit several asteroids over the next decade or so. Not just any asteroids, but ones that share an orbit with Jupiter, called the trojan asteroids.

This article is a little different from earlier ones: It’s not about the science per se, though there’s science in it. Instead, I wanted to take some time to ponder the way we name things.

I think this is an interesting and even important issue. I’ve written about it before, notably and obviously when it comes to JWST, and also back in 2020 when a telescope was named after an investor who had also donated money to Trump’s Presidential campaign. Naming things like observatories and space missions after people is nearly always problematic, because no human is ever 100% awesome.

It’s also sometimes difficult to agree on what behavior counts as troublesome, especially as ideas and mores change over time. I’m not the first person to notice or mention this, of course, and there are some very deep conversations to be had on this topic — a recent thread on Twitter has some interesting insight into this.

But Lucy…

This mission was named after the first nearly intact Australopithecus afarensis fossil found in Ethiopia in 1974. The reasoning is that the asteroids Lucy will investigate are like fossils of the early solar system, leftovers from the planet-building process, and will reveal our history just as the Lucy fossil in Africa did.

I am very OK with that. There’s more in the article, and I’ll humbly suggest it’s very cool and you’ll like it. It’s free, so go read it.

But, as usual, there were details I wanted to include in my article but it started getting too long, so I had to remove them. But hey, I have a newsletter.

I did mention that the trojan asteroids got their name because the first few were named after characters in the Trojan War myth. It became tradition after that. Even more fun: There are two groups of these asteroids; one orbits 60° ahead of Jupiter and the other 60° behind (these are gravitational sweet spots, stable regions where an object that orbits there will tend to stay there; I’ve written about this before if you want details). Also by tradition the ones ahead — called the leading asteroids — are named after Greek figures, and the ones behind — the trailing asteroids — after Trojans (though there are exceptions). Cool!

But… we know of thousands of these asteroids, far more than there are characters in the mythological telling of the war! So, in 2018, the International Astronomical Union (the keeper of official names and naming rules for cosmic objects) decided that any trojan asteroid smaller than about 22 kilometers wide would be named after Olympic athletes. I didn’t know this until I was researching the SciAm article, and love that! And even better, it still ties in to the ancient Greek life.