lime green disk shaped and tranparent with no lights or any other noticeable markings

came home to my trailer parked brhind the store where i work at 8:30 a.m. i heard a unfamiler noise and about 400 yards away i saw it so i reached right inside my door and grabbed my 7x35 binochars and i was able to see a  lime green disk shaped object and hear it at the same time.there seemed to be a small amount of blackish colored smoke, but it was very little and could only with binoculars.i watched it for about 5 minutes it didnt seem fast but i  watched it untill it was a few miles away. it moved ina steady line never and never eradically .to me it almost sounded like big wind generator the kind with a 15 foot propeler it.but a little different. it was a very calm quiet morning no wind. the stangest thing of it was that there was no lights or markings of any kind it was a light emerald green color and almost if not transparent .thak you