You’ve no doubt heard some star names such as Polaris the North Star – or Betelgeuse in the constellation Orion. But, although it’s also a star, our sun doesn’t have a generally accepted and unique proper name. It’s just the sun.
You sometimes hear people use the name Sol for our sun. Sol is the Roman equivalent of the Greek sun god Helios. And maybe in earlier times people did actually use these names. According to straightdope.com, the first cited use of Sol as a proper name for the sun is the 1450 Ashmole Manuscript Treatise on Astrology, which stated:
Sol is hote & dry but not as mars is.
So much for ancient knowledge.
And meanwhile neither Sol nor Helios is an official name for the sun, according to the International Astronomical Union (IAU), the international body of astronomers which since 1922 has charged itself with the responsibility for naming all things celestial. By the way, the IAU is virtually alone in the world in suggesting we all use Sun and Moon, rather than the lower-case sun and moon. Most astronomers do capitalize these words (frequently along with other non-standard capitalizations such as Galaxy, Solar System and Universe), but most media organizations (which tend to use media stylebooks such as the AP Stylebook) don’t.
So the sun doesn’t have its own name. But it does have a symbol that’s exclusively its own. The sun’s symbol is a circle with a dot in the center – used in mathematical formulas.
In being nameless, our sun has company. There are several thousand stars visible to the eye, and only a few hundred of them have actual names, as opposed to designations. Astronomers use the Greek alphabet to order visible stars in each constellation, according to their brightness. To identify stars invisible to the eye, astronomers turn to star catalogs, which assign a number to each star according to its position in the sky.
Plus, nowadays, there are thoughts to be planets orbiting many if not most stars. Those extrasolar planets haven’t yet been given proper names either, and the IAU has gone back and forth on its decision to name or not to name extrasolar planets.
Meanwhile, if you ask in a public forum, you’ll find many who swear the sun’s proper name is Sol. When all is said and done, I guess, it all comes down to who has the authority to give names to objects in space. Most astronomers tend to go with the International Astronomical Union, but some – like the astronomers affiliated with Uwingu – are trying to change that.
Bottom line: Our sun doesn’t have an official proper name, according to the International Astronomical Union. In antiquity, the names Sol and Helios referred to ancient sun gods and perhaps the sun itself.