Do you believe in angels that had fallen into the earth to watch and guide us?. It was all in the book of revelation where angels where described by and of their traits, but it is possible that those angels that descended from the heavens where some extraterrestrial beings that was given the name angels but in the perspective detailed encryption it was really meant to be "messengers". Are these messengers of God are of some beings that has the ability to fly and levitate nor they used some advance devices like Jet packs to ascend and descend from the heavens, because none of the description said that angels had wings. Maybe the interpretation of our ancestors that they are like birds that can fly so they put them with wings in their creation of the representation of them. As I also read the booked of revelation means these beings had the seal of God, thus this means that they have a mark that tells our ancestors that they are angels because as they said they were also human like beings and because of that seal our ancestors distinguish them from other human. 

Really more mystery are hidden by us and all that we have now are the questions and speculation that God can answer when the second descending of his only son Lord Jesus will came to its perpetuity that all of this will be thoroughly answered.