The Godfray and Turner references say that the Moon's annual path around the Sun is concave.  Other reference like this one say that it's convex.  That seems like a conflict to me.  Now, maybe you'll claim that the Godfray and Turner references are looking outward from the POV of the Sun, and the other references are looking inward at the entire system, and that explains the difference.  But I still don't acknowledge a distinction between convex/concave when looking outward from the inside, and convex/concave when looking inward at the entire system.  Hopefully Marc will clear up some of that when he responds to my question above. -