I hate to argue with astronomers, but they aren't in charge of names. Well, by default in most cases they are, but that's because most astronomical objects are unknown to the general public. There is a Dark Side of the moon, the moon is Luna, and the sun is Sol. Get over it. Instead of explaining that there is no dark side they need to explain tidal lock. Words change and so do names. Pink Floyd and science fiction writers have evidently more influence than astronomers, again get over it.
I agree that for consistency sake, we should use the Roman names. Terra, Terra Mater, Tellus, or Tellus Mater for the Earth. Sol or Sol Invictus for the Sun. Luna or Diana for the moon.
The problem is most people don't use those names. Ask an astronomer and the name is the Earth, the Sun, and the Moon. Ask a high school student and the answer is the Earth, the Sun and the Moon. Ask a factory worker and answer is the Earth, the Sun and the Moon. If usage is most important, then the names are the Earth, the Sun and the Moon. I dislike the inconsistency also, but there is a lot of inconsistency in English.