The moon orbits near the equator of the Earth. In the southern hemisphere, we are standing at the opposite side of the globe, from a person who is standing in the northern hemisphere. So, we are literally standing upside down with relation to the person at the other end. We, therefore, see the moon from a completely different vantage point. So, if a man sees the moon crescent facing up in the northern hemisphere, it’ll appear upside down to a person in the southern hemisphere.