What is the proper name for the sun?
Dear Straight Dope:
I was thinking about the fact that the word "sun" is not capitalized. Seemingly this in not the name of this large star which we spend our time spinning around. What is the proper name of the sun, or why isn't it referred to as The Sun. While you're at it, you might as well tell me what they call the moon as well.
Well, back in the day, they did used to capitalize it. Of course, that was back before those nutty folks started looking up into the sky and coming up with zany ideas about how maybe those lights were, you know, kinda the same things as The Sun. In light of that, it would be awfully arrogant to call it The Sun; after all, when you need to have that hernia checked out, you don't go see The Doctor.
That said, there are proper names for these things, just like your physician is Doctor Feeblebrinx.
At some point, very possibly in antiquity, someone decided to name the sun after the Roman god of the sun, Sol. Seems fairly sensible to me. Going after fact here, the Oxford English Dictionary offers that in Canterbury Tales (1386), Chaucer writes "Sol gold is, and Luna silver we threpe." This would appear to be metaphorical, but the OED credits gold and silver as actual, obsolete definitions for Sol and Luna. The first cited use of Sol as the proper name for the sun is the 1450 Ashmole Manuscript Treatise on Astrology "Sol is hote & dry but not as mars is."
However, hidebound by tradition as we are, you generally only see scientists, nerds, and science fiction fanboys - wait, I'm being redundant. Well, you get the point; most people still just call it the sun.
Likewise, the moon has a name, Luna, as alluded to above. In the OED, the first cite is Skelton Bowge of Courte (1529) "Whan Luna, full of mutabylyte, As emperes the dyademe hath worne Of our pole artyke."
The etymology of Sol is given as "[L. sol - SUN (for earlier *saol, *sawol),", and for Luna, simply "L. luna MOON". Merriam-Webster clearly notes Sol as a name for the Roman sun god. Let's also not forget words such as solar, solstice, lunar, lunatic...
People being people, and not necessarily given to agree on change, these names aren't "official," really. That noted bastion of academic wealth, The World Almanac and Book of Facts, doesn't even refer to Sol or Luna in its astronomical data section. They are, however, pretty much the only proper names in common use for these two stellar bodies among English-speaking folk.