Well, supposedly Mars just means "male," Sol means "sun," and despite Venus's name being related to sexual desire in it's origin, everyone is still focused on uranus (which apparently means "the heavens" in origin... which is unlikely to make it less used as the butt-end of jokes)
One way to think about it is that in all the countries/empires/cultures that these names originate in if they could see the other planets and moons in as much detail as we can they would describe them object class wise as "like the sun" or "like the moon." You have to remember a lot of this comes from the people that would name a set of twins "Augustus" and "not Augustus."
So we have MoonMoon the dog and MoonMoon the celestial object.