When you head over to this page, you see a list of all upcoming sets with their expansion symbol except for the symbol of Eldritch Moon. However, all expansion symbols follow a very similar URL pattern. When I use that logic to and browse to this url : http://magic.wizards.com/sites/mtg/files/images/featured/EMN_SYMBOL.png I can see a symbol that looks like a moon but is definitely not an expansion symbol. Is this a joke, or a clue? In case this is already public info, you can lock this thread.
I'll post a screenshot just in case the url stops working:
I'll post a screenshot just in case the url stops working: