Lights in the sky over Washington State

It was in the mid-70's that this siteing happened. I was around 9 or 10 years old. It was a very dark night, with no moon in the sky, so the stars were very clear. I was living in the Eastern part of Washington state, which is largely farm land. I remember being called out of the house to come and see something. What I saw was several lights, about 7 or 8, moving around in the Eastern sky. They looked no different than the stars, except that they were moving. They floated around each other for awhile, then one or two of them would streak off and vanish, only to appear in the opposite direction from where it went. Sometimes the objects would merge, then spread out from each other. This went on for about 15 to 20 minutes, it could have been more. My father, who is a farmer, along with my mother, brother, and sister all saw this.
Date is approximate.  PD