Tablet penned by strange alien found between poles of the moon (8)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

[ E(abbrev. for an Ecstasy tablet) contained in ( penned by ) anagram of ( strange ) ALIEN ] contained in ( found between ) S,N(abbrev. for “south” and “north” respectively, the 2 geographical poles on earth).