Strange sound that hovered in sky early in morningI was sleeping with my windows open. I heard a very loud truck or something similar. I was waiting for the sound to go away but it was hovering. I woke up more now that this noise was not going away. I then thought it could be an airplane but it just didn't sound like anything I've ever heard. I got up to look outside but couldn't see anything as my backyard is all tall trees. The noise went away and I went back to bed. About 2 mins later the noise returned. It hovered for another minute and left. Nothing has happened since.