Noticed very bright color changing "star" 15 - 20% above horizon which had several smaller lights circle it.Noticed an object in the NW Hemisphere 15 - 20% above horizon. Looked like a very bright star which flashed brilliant red, blue and white light. Several smaller lights could be seen encircling the most brilliant. It looked stationary for about ten minutes and then we noticed a slight side to side motion and it began to descend toward the horizon. It would come up and then down again until finally at 10:30 p.m.(looked at watch) it went behind the mountain. The trajectory was down and to the North.Couldn't see an object or if the lights were associated with a fuselage of any kind. The light of the object was very bright and didn't seem to dimminish throughout the whole event.