I like astronomy, and I also like etymology. So a while ago, I set out on a project to combine the two. Astronomy is (admittedly,) one (of many) thing(s) that just about all cultures have in common, and I really enjoy learning about the various myths and figures that people thought deserved a place in the sky.

When it comes to modern usage, three cultures have left the strongest impression: Greek, Roman and Arabic. Most of the constellations we know today were described by Ptolemy, while most of the stars in them have Arabic names. Here and there, there’s a scattering of Latin, and – as I was surprised to find – Italian, Persian, Hebrew, and even English. I was curious, wondering if the northern and equatorial latitudes were dominated by classical names, while more modern schemes (which I assumed to be mostly English and Latin) crept in further south, applied to stars invisible from the northern hemisphere.

To do this, I collated a list of all IAU-approved star names. In my mind, this is the closest to an ‘official’ list of star names, though it is of course very Eurocentrically biased for historical reasons. I used VizieR to make my catalogue, but later found this list, which would have been much easier. I then set about the task of assigning each a language of origin. For some, this was simple: Alkaid, Bellatrix, and Electra are reasonably obviously Arabic, Latin, and Greek, respectively, while the majority are (to me) less obvious, such as Denebola and Sualocin. These resulted in a lot of Wikipedia searches.

In the end, my list contained 336 stars, of which 209 have Arabic etymology, 57 Latin, and 28 Greek. If you’re keeping count, you’ll then know that that leaves 42 stars with ‘other’ etymology. This is a lot more than I expected, outnumbering Greek, and getting pretty close to Latin. I’ll put those aside for now, and concentrate on the Big 3.

That means it’s time for graphs! So, as a reminder of the original question:

Does the language of origin of star names vary with latitude?

The short answer is “no, not really”:

This figure has a fair amount going on, so probably warrants explaining. In the top-right is a map of the sky, oriented like a world map, using an equirectangular projection. The coordinates “right ascension” and “declination” can be thought of as longitude and latitude, respectively – both can be measured in degrees (although astronomer prefer to measure R.A. in hours, and yes, it increases right-to-left). Anyway, coloured circles represent stars with names from the Big 3 languages, while black crosses are other languages. If you look closely, you might be able to make out a couple of constellations:

  • Part of Ursa Major (the plough/big dipper) is at the top centre with its seven Arabic stars
  • Orion appears at (90, 0), very much shrunken by the projection. The one Latin star (Bellatrix) is a purple island in a sea of green
  • Above and to the right of Orion, at about (60, 30) the dark blue blob denotes the Pleiades (or seven sisters), where ten stars with Greek names are piled on top of each other

Below and to the left of the sky map are charts showing the fraction of stars from each language in bins of right ascension and declination. Declination is the one we’re looking for, as that corresponds to the latitude on earth at which a given star passes directly overhead. The trends are roughly what we’d expect: Arabic is dominant, and Latin and Greek get 10-20% each. Toward the south celestial pole, we start to run into issues of having very few named stars; in my catalogue, there are only three stars south of -60° S, and none between -70 and -80. There might be hints of an increase in Latin there, but there are simply too few stars for this to be convincing.

We can compare this to the distribution in right ascension. If stars’ names depend on latitude, there shouldn’t be any trends in RA. Here, we see basically the same pattern, and we can identify peaks, where, say the Pleiades dominate the Greek contribution around 60°.

So, having debunked my original prediction, let’s take a look at the miscellaneous etymologies that I found while collating my catalogue. Here’s the sky distribution again, focussing on those other stars:

There’s something interesting to say about most of the stars here, so let’s go through them.

The first thing to note is that five different stars share two Italian names. I can only guess this is due to confusion when copying star maps over the ages.

The four English contributions consist of two stars named after people (one conveniently including a date), one description, and ‘Peacock’. ‘Peacock’ and ‘Avior’ (which I’ve labelled as unknown) were both named for use as navigation stars for the Royal Air Force, as they didn’t appear to have existing names. ‘Peacock’ is simply named after its host constellation, Pavo; I have no idea where ‘Avior’ came from, and haven’t been able to find any information on it. If we follow the pattern, it should be called ‘Keel’ because it’s in Carina, but this is probably the wrong place to expect consistency.

There are a slew of languages that get one star each. There’s not much to say about these, other than how surprisingly ancient some of the languages are – if ‘Sargas’ really is Sumerian (which is uncertain), the name could be up to 5000 years old. There are also a few more unknown names – entries that simply appeared on someone’s star chart and got copied.

Finally, we reach Rotanev and Sualocin , courtesy of one Niccolò Cacciatore, who when helping to compile a catalogue in 1814, couldn’t resist Latinising his name to Nicolaus Venator and claiming ownership over the two brightest stars in Delphinus (the Dolphin). I can’t deny I’d be tempted to do the same – it definitely beats paying for them.

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