Saucer Shaped Craft, Late 70's in suburban Minneapolis, around 9pm. seen at extremely close range of 40 feet

1 Saucer shaped object only 40 - 60 feet away at its closest, seen from large picture window from a home on a hillside.  it was traveling about 3 miles per hour (slow)  took about 45 seconds to disapear over trees in small forest area across the street.  at its closest  you could see circular lights all around the craft, the craft was metalic, you could actually see seems, etc. no top dome as you see on typical drawings. the circular lights seemed to be moving slowly (rotating) around the craft. the seams etc. gave the contrast to notice it was a ring that rotated independantly,   NO sound at all!  this craft was witnessed by 4 people including my Grandmother, Aunt, first cousin and myself.  I was 13 or 14 years old, visiting mineapolis from california for the summer.  the year was 1976 - 78,  can pinpoint the year by talking to relatives if needed.  the month was July or August and the day was a tuesday. my favorite show baa baa black sheep was on tv at the time.  we reported it to the police dept. they laughed? I had vivid nightmares of Large eyed aliens for some time - a truly frightning experience.
Date of incident may be approximate, although the witness does not indicate that fact.  PD