Editing - Problem

We wanted to add a picture of a moon to show the passing of day in our film and it was to also follow the conventions of werewolves coming out at night and turning in the full moon. The big problem with it though is that our media teacher explained to us that to photograph or film the moon would be really hard as you need really expensive equipment to get a photo that will be clear enough. Our teacher tried to take a picture for us with his expensive equipment but even then it wasn't good enough for the effect we wanted in our film so we ended up buying a stock footage moon and just putting that in instead.