Recalling my first UFO sighting....1976

(Uncertain of date, estimating fall since we had clear view of nearly the entire lake)  It was dusk. A clear starry night was ascending upon 3 teenaged cousins who were just cruising around listening to tunes, in a Chevy Impala.  The sunset was behind us as we turned in an easterly direction, up the hill from Highway Y on Lochcrest Blvd., toward the house on Little Muskego Lake, located in S.E. Wisconsin.  As the driver (my cousin) crested the hill, we could see the hazy glow of Milwaukee's city lights to the north east, as well as the house lights that dotted the shoreline all around the lake. I don't recall Muskego's Dandelion Park ferris wheel being illuminated, which again makes me guess this may have been later in the year, when the park was closed for the winter.
 The driver (my cousin) stopped the vehicle abruptly, pointed to the the sky above the lake and yelled "WTF is that?!!!"  The three of us saw an intense bright white orbital light (close to blinding intensity), hovering about 200' to 500' above the south end of the lake.  Suddenly, the orb light traveled at extreme speed to the far north end of the lake (distance is about 1 mile). Then the light maneuvered instantly up, down, back and forth across the lake, precisely halting it's movement at several different locations.  There were no trails or smoke of any kind behind it.  The orb hovered for a few seconds over the south end of the lake directly in front of us before shooting straight up into black space.
 We were awe struck by what we had just seen! My cousin quickly drove down to their home on the lake. The three of us ran inside the house to tell our parents about the sighting. I'll never forget the sound of the door hitting the wall so hard as we barged in, that it made a hole in the wall. My uncle was angered by the damage we caused the wall, and refused to hear a thing about our incredible sighting. He wrote us off.....saying we were probably smoking wacky weed.
 We know what we saw that night was real.  There were several documented UFO sightings in Wisconsin, the USA, and other locations on Earth during that time period.