Close encounter over Merrymeeting Lake

I was only six when this occurred, but i remember this event crystal clear, and the sighting was also corroborated by my sister, who was 16 at the time.  
Around 4th of july, 1991, my family was vacationing in a lakeshore cottage on Merry meeting lake.  My sister and I were fishing on the dock, when all of a sudden out of no where, a large metallic spheroid appeared about 100 yards in front of us and only about 30-40ft above the lake.  The craft was hovering slowly and moving directly towards us.  It looked like a giant metallic football.  The craft had no wings, windows, markings or lights.  This was certainly no blimp or man made aircraft.   
The object was moving around 10 mph and was dead silent.  The object hovered over us and looked like it barely cleared the trees as it passed.  We only saw the object for maybe 30 sec to a min but the craft was close enough to throw a rock at it.  
This sighting profoundly changed my life as i have always believed in life beyond this planet ever since!