Yes, as far as I know, it's always "the moon" when referring to the moon that revolves around the earth. Can you give an example of "moon" without an article? I'm not familiar with any such usage.
When referring to our planet by using its name, you can use "Earth": Mercury, Venus, Earth, Mars, etc. "Earth is the third planet from the sun." If you mean the non-countable "
I would agree with CalifJim about his views. Look at the following sentences, you must have the article to make them sensible sentences, as far as I can see.
1.On July 20, 1969, Neil Armstrong became the first man to step onto the surface of the Moon.
2.The Moon is 384,403 kilometers (238,857 miles) distant from the Earth.
If I had millions of dollars, I would distribute it among the poor.
So the above doesn't sound you an unreal stiutaion in the past. Simply it means that I didn't have millions of dollars two or three years ago. You consider this is a real situation. I would agree with you.
To express a remote possibility for the present or future:
If I won the lottery (today / in the future) -- after all, it IS a remote possibility -- maybe I'll win, THEN I would distribute it (as soon as I won it or soon after) to the poor.
To express a counterfactual, something that was a possibility in the past, but did not happen:
You are very clever at English. I am glad that we have a man of your calibre around ús. I reflected on this many times before posting here. The point you made didn't cross my mind. I respect to your prowess in English.