White, orb of light hovers, then darts into Western sky over downtown Morgantown

Friday, October 17, between 8:10pm and 8:15pm, Morgantown, West Virginia - over South Park area. Large, white orb of light hovers then darts from Northwest sky to Western sky where it disappeared in the distance.  The sky was cloudy, but there is always a great deal of ambient light in our area coming from the downtown area and a nearby mall complex.
 My wife was standing on the front porch of our house, looking north-west. She noticed a large, “softball sized,” white orb below the cloud cover.  Possibly 250-400 feet above the ground and maybe four or five blocks north of our house.  It was hovering/hanging in the sky when she first spotted it.  
As she tried to comprehend and understand what she was looking at, it darted away, and crossed the entire sky/horizon in under a second.  It did not leave a visible trail or change directions.  At first she thought it was a star or low flying plane, but realized it was a round orb of light.  It dashed across the sky in a straight line, and she thought it traveled horizontally without gaining or losing altitude.  Moved at such a fast speed, she is confident it was not a helicopter, drone or plane.  It had the appearance of a shooting star except it started from a dead stop.  It was also eerily quiet outside that evening and the object made no noticeable noise either while hovering or moving! across the sky.