Disc shaped craft with flashing red and green lights in a circular motion noticed and witnessed going down. With a pulsating humming so

I was a young child probably five years of age.  I was with my father my sister and my aunt we were at one of my father's co-workers houses they were playing basketball that night.  I was sitting on the hood of my uncle's a Jeep and saw something come over a tree line in the distance it was round and disk-shaped and had a slightly smaller protruding cone shaped bottom section that have green and red lights flashing in a circular pattern going counterclockwise.  There was a bizarre sound that sounded like a pulsing hum or a pulsating hum ever so briefly as The Craft went past in a southerly direction and appeared to go down behind a hill that was no more than 900 yards away.  
I showed my sister.  Who ran and got my aunt, who also tried to get the attention of some of the other people there but the craft was already out of sight and everybody just kept playing basketball at that point.  I know what I saw. And I also know that it was very quiet, but the sound made wa! s unmistakable it was a pulsing hum sound or some sort of a modulating hum sound.  The lights that were flashing in the circular pattern were very much looked like Windows.  And if I had to guess they appeared to be 3 feet by 3 feet square from the distance that I was at. The craft was large I would guesstimate 50 to 70 feet in diameter it was moving very slow no more than 20 to 35 miles per hour.  I remember this incredibly vividly and have ever since I was a child.  I am currently 44 years of age.
Witness indicates that the date of the sighting is approximate.  PD