I was in my pool vacuuming the pool. Facing west, I just happened to look up and I notice a black ball floating along at treetop level very slow,going south. it was just across the street from my property,about 150 maybe 200 feet away. I first thought must be a drone, but as I watched it i notice it's not making any sound. And for it to be as big as it is, about 4 to 5 foot round, i should be able to hear the prop wash if there is any. I was shocked I just could not stop looking at it. I didn't want to take my eyes off of it. And I fallowed it with my eyes as it floated un wavering, steady, straight line path, same altitude until compleatly out of site. At least a mile or more away.