Lupin's Boggart- really the full moon?

[pippin_999]

No: HPFGUIDX 72714

It's been noted many times on this list that while Harry's boggart 
has the same effects as a real Dementor,   Lupin's full moon 
boggart doesn't cause him to transform into a werewolf. Various 
explanations have been offered.  Perhaps imitating something 
as vast as the moon is beyond a boggart's power, or maybe the 
whole thing is a Flint. 

I have an alternative explanation. What if Lupin's"silvery white 
orb"  isn't the full moon at all? After all, he never  exactly says
that's what it is. He only asks, " Or did you realize that the
Boggart changed into the full moon when it saw me?"  What if 
Lupin's boggart is actually  one of those "glass orbs" "softly 
glowing" from the Department of Mysteries? What it it's the 
Prophecy?  

Parvati thinks  that Lupin's boggart is a crystal ball, which could 
be a hint to the reader.  We also hear that Lupin fled from 
Trelawney when she offered to crystal gaze for him. (PoA ch.11) 
Was he simply trying to avoid an encounter with the batty 
divination teacher or does he have reason to  dread her 
prophetic powers? 

Pippin