Why is Earth's moon called "the Moon"?

Question

I've always wondered why our moon doesn't have a name, like all the other moons. What makes our moon so special that it's called "the moon"?

Answer 1

It's closest object to earth.

Answer 2

Actually our moon does have a proper name. It is "Luna". We get the word lunatic and lunar from this. The word "moon" is a common noun whereas "Luna" is a proper noun. Similarly the name of the sun is "Sol" and the name of the earth is "Terra".
Notice that whenever we use the words earth, sun and moon we usually precede them with the word "the". This is your best clue that the words are common nouns and not names.
We can say the words "men", "a man" or "the man" when we are talking about any person or a specific person, but each has a proper name as well.

Answer 3

The name "Moon" is ancient Germanic. When we discovered the orbiting companions to other planets, we applied the name of our orbiting companion to the other bodies.