Who are the “angels” John wrote to at the churches in Revelation?


“To the angel of the church in Ephesus write:
These are the words of him who holds the seven stars in his right hand and walks among the seven golden lampstands. Revelation 2:1
            In Revelation 2 and 3, John wrote to seven churches and the “angels” over each church.  The word in Greek is aggelos and means “angel or messenger.”  The word is used 180 times in the New Testament and each time seems to refer to a supernatural being.
            However, in this context, why would John be writing to an angel?  He has no authority over the angel.  If we use the word “messenger,” then a pastor can be a messenger.  The pastor has authority over his congregation, which these letters are meant to encourage new behavior.  His job would be to send a new message to his people, saying either God is happy or sad with them and they need to change their practices.