When the crescent moon is lit from the bottom, it resembles a bowl that can “hold water” — hence, it is oftentimes called a “wet moon.” (Of course some people will say that the moon is full of holes like Swiss cheese so it can’t hold water. 🙂 )
When the moon is lit from the side and appears vertical (like the letter C), water will pour out and it is called a “dry moon.”
Actually the crescent moon can be “wet” or “dry” depending on the time of year and location of the viewer. In winter months when the earth’s axis changes its tilt relative to the moon’s orbit, the moon is seen as lit from the bottom. That’s why the winter moon is also called the “Cheshire moon,” named after the smiling cat.
Today’s moon phase is a waning crescent according to this calendar. The sky is bluish (not black) in the photo because it was taken just before sunrise, apparently the best time to view it; the craters and lunar mountains can be seen from a quarter of a million miles away.
Wet or dry, the crescent moon is simply an interesting sight to behold.