There was once a Straight Dope mailbag on this topic as well:
Uranus is the Roman term for the eldest god; the Greek version of the name is Ouranous. The planets use the Roman names, even though the Romans largely borrowed their mythology from the Greeks. Uranus/Ouranous was castrated by his son Saturn/Chronos, who in turn was overthrown by Jupiter/Zeus.
The other equivalents for planetary names:
Mercury/Hermes
Venus/Aphrodite
Mars/Ares
Nepturne/Poseidon
Hades/Pluto
See Post #12. The Aztecs had a cool multisyllabic name for the Sun; I’ll see if I can find it.
J.R.R. Tolkien wrote about the Lamps of the Valar, Iluin and Ormal, which cast light over the world. Later, after the treachery of Melkor, the mortally-wounded Golden Tree Laurelin bore a single fruit, which was hallowed and placed in the heavens, guarded by a fiery Maiar, becoming what we know as the Sun. According to the Encyclopedia of Arda, alternate names include Anar, Anor and Vasa.
Right - science fiction is wrestling with an issue we probably won’t ever have to. But why shouldn’t “Sun” and “Earth” be considered “proper names”? Why does the name have to be different from the one people actually use to make it proper? It’s the irritating pretentiousness of using Latin terms when English ones would work just as well that annoys me. Calling other stars “suns” is also something that makes little sense to me. The name we use for it - “the sun” - implies that it’s unique in the universe. Of course in reality it’s not unique, but it seems weirder to me to call any random star “a sun” - also a convention from lower quality sci-fi in my experience - than to recognize the obvious: that “Sun” is its name in English. It strikes me as rather a mark of crappy writing because I’ve never seen it in good writing, and because a good author wouldn’t have to resort to pretentiously renaming our planet and star to their Latin translations.
What names do “good” writers use then?
Uranus is a Latin transliteration of the Greek Ouranous. The equivalent character in Roman mythology was Caelus. If you can find any evidence that this is not correct, I’d be happy to hear it. But “Uranus” is a Greek god; it simply happens that we’ve used a Roman transliteration of his name.
Astronomers already need a proper name to distinguish it from other stars. And we call it “the Sun”. It’s unambiguous, especially since astronomers usually refer to other stars as “stars,” not “suns.”
Galaxies can be a little more confusing, because other ones are referred to as galaxies, and ours as the Galaxy (capitalized). So sometimes it’s referred to as “our Galaxy” for added clarification.
As has been acknowledged in this thread, “Sun” is only the proper name in English, it’s not universal on this planet. So, why not come up with a slightly more linguistically neutral name? Sure it could be Prithvi, but most Western sci-fi writers are more familiar with Latin than with Sanskrit.
The words “earth” and “sun” and “moon” have more generalised meanings in English that “Terra,” “Sol,” and “Luna” don’t. It seems perfectly logical to me to come up with names that are less ambiguous.
It might not be real. It might not be what you would have chosen. But I certainly don’t find it ludicrous or pretentious. It seems perfectly logical to me. Anyway, it’s just fiction, so why sweat it?
Every solar system will have “a sun.” What else would you call it?
None of the other words are linguistically neutral either. It’s not called “Mars” in Chinese, for instance (they call it Huoxing, which translates as “Fire Star”).
“Moon” has a more generalized meaning; many planets have moons. I don’t see this as a huge problem, though - it doesn’t pose any confusion now to talk about “the Moon” and about Saturn’s moons. I’m not aware of any similar general meaning for “Sun” or “Earth” - sure, “sun” can sometimes be used to mean “sunlight”, and “earth” can mean “soil”, but that’s hardly confusing. If you’re claiming that “sun” also means “the nearest star to the planet we’re standing on”, then I would say that that’s not true. Probably because we haven’t ventured outside our solar system yet, English (at least) has not yet developed a word for such a thing. Should it happen, no doubt we’ll come up with something.
It’s fine. I find it annoying, but there’s no law saying I have to read bad sci-fi. But this thread was about the real name of the Sun. And while you may want to give it another “real name”, it’s emphatically not correct to claim that “Sol” is the real name - not yet, anyway.
Conventionally, we call them stars.
Convention isn’t at issue here. If you were living on a planet orbiting Alpha Centauri, would you refer to Alpha Centauri as “the star” or “the sun”? I’d say the latter. From that perspective, Alpha Centauri would be “the sun” and the Sun or Sol (or whatever else you want or don’t want to call it) would be “a star.” And it doesn’t even matter whether I’m right or not, because this is fiction and in fiction you can make up your own answer. My point is that there’s nothing illogical about this answer, even if it’s unlikely.
But “mars” is not as ambiguous in English. “Sun” is “the star that the planet I’m on is orbiting” and “earth” is “dirt,” both of which are proximate enough to make the term ambiguous.
Which is completely missing the point of a fictional world in which other solar systems are inhabited.
And many science fiction writers have decided to postulate that “sun” will mean “the star that the planet I’m on is orbiting” and our Sun will be “Sol.” It’s fiction and it’s perfectly reasonable.
I’m not the one who started ranting about “bad sci fi.”
No, I did that. When I suggested that the fact that a particular naming convention is used in bad sci-fi doesn’t have much bearing on the real world. You’re still arguing about bad sci-fi, which I don’t understand, given that it’s not the topic of the thread.
And even though you could use “the star” or “Alpha Centauri” in astronomical contexts (“this planet orbits Alpha Centauri every 382 days”), you will probably use “the sun” in the general contexts I referred to above (“sitting in the sun, sweating into my pressure helmet”).
I did mention the bit about capitalization; “the Earth” is not ambiguous. (Any more than “le havre” and “Le Havre” are ambiguous in French.)
Maybe it is used in bad science fiction. So what? I’ve also seen bad science fiction that calls a confection of batter cooked on a griddle a “pancake”. Should I stop calling those things “pancakes” just because that’s the term used by some bad SF?
It’s also used in good science fiction. And in fact, it’s the best term to use in good science fiction (at least, that which involves folks living on other planets). If you’ve got a farmer living on a planet orbiting tau Ceti, he’s going to get up before sunrise to go dig in the earth. He’s not going to get up before tau Ceti-rise to go dig in the planet. And he’s certainly not going to get up before zark-rise, if you decide that “zark” should be the word for “the star which happens to be closest to the planet we’re on”.
The fact is, that if you’ve got a context where people are living on other planets (as you do in much science fiction), then you need both a general term for “star that gives light to a planet” and a specific term for “the particular star that gives light to the planet humans evolved on”. Since the former sense is the one used more commonly in nontechnical contexts, the current nontechnical term will in all likelyhood remain attached to that sense. Which means that a new technical term will be needed for the latter sense. And since technical terminology often comes from Latin, the best candidate for that new technical term is “Sol”. I’d be happy with using the Greek “Helios”, too, but that’s not the convention which has taken hold, and besides, “Sol” is just a transliteration of “Helios” anyway.
I thought that Cicero used the “Uranus” form in De Natura Deorum, but on checking I see that I was mistaken. I stand corrected. (Or sit, rather, in front of my computer, but the metaphor remains valid.)
Because it’s fucking stupid to walk outside your biodome one morning, mop the sweat off your brow, and say “Jesus! The geminorum zeta sure is hot today!”
–Cliffy
But think of the romance in sitting out on the porch swing, holding your true love’s hand in yours, watching Sol set, and then basking in the light of Luna . . .
I’ve made my point - it’s factually incorrect to claim that “Terra”, “Luna”, or “Sol” are “proper” names for any astronomical body. The fact that they’re annoying and pretentious is just my opinion. But if you disagree, it just means that you’re annoying and pretentious. 
I don’t care either way, and I don’t know why you’re continuing this hijack. The fact is that “Sol”, “Terra”, and “Luna” are not the "real’, “technical”, or “proper” names of any astronomical body. They are presented that way in pulp sci-fi novels; I have not encounted them in good science fiction, but I suppose it’s possible some author has used them for that purpose. Regardless of their usage in any calibre of novel, they are not the “real” names of the things in the real world, as was asserted several times in this thread. I brought up the contrast between reality and bad sci-fi for a specific purpose: to remind people that convention among the lesser lights in science fiction is not the same as convention in the real world.
I’m sorry if you feel I’ve insulted some beloved author of yours, but you’re continuing a hijack that is very, very far off the topic. Factually, “Sol”, “Terra”, and “Luna” are not in any way “official” or “real” names for those bodies, unless you’re speaking Latin. That’s what this thread is about. That was my point. I’m done.
I don’t think you know what the word “transliteration” means.
Looking at your post again, I have no idea why you posted what you did in response to the quoted portion. It’s a complete non sequitur. Please mentally remove my response and insert some scathing comment about adult illiteracy or checking your glasses prescreption or something.
Well, sir, in view of the fact that Robert A. Heinlein, Arthur C. Clarke, Spider Robinson, Marion Zimmer Bradley, Isaac Asimov, and numerous others used the Sol/Luna/Terra conceit regularly, I would say that the problem here lies more in your standards for “good science fiction” (whatever that may be, and a subject more suited for Café Society than GQ) than in anything “real.”
I do not recall the Coasters singing, “The Panthera tigris Sleeps Tonight”, nor do I generally talk to my landlady about the Pinus sylvestris she has growing about the property. In fact, our other neighbors insist that what they used for fill in the driveway was “gravel” and not a cobble-ized dolostone/schist mix. I recently had to discard an overripe banana, as it was attracting Drosophila and I didn’t want them mutating on me.
In sum, pretentiousness lies in the eyes of the beholder. The customary usage for “stellar object providing the chief natural source of illumination” in English is “sun,” although of course in Latin, Spanish, Italian, etc., it’s sol. Following a longstanding tradition, the international usage for that beast which a Frenchman would call a chien and a Spaniard a perro, but we English-speakers refer to as a “dog” is the Latin Canis. Likewise the international standard term for the stellar object which Mars revolves around, customarily referred to in English as "the Sun and in French as le soleil, is “Sol,” the Latin name attached to it. Likewise its third planet, known in English as “Earth,” is “Terra” and that planet’s natural satellite, “the Moon,” is “Luna.” According to Mr. Bush, in a few years we will have a manned expedition to Mars. Presumably they will observe Phobos and Deimos moving across the sky, and see Earth as an “evening or morning star” in the same way as we see Venus. Accompanying it will be a dimmer body. From their vantage point, what will they see as a moon? And why would they choose to make that distinction?
I’m with Chronos on this one.
And the Aztecs called the Sun “Tonatiu.” I like it. I’m gonna start using it, and you should too…