Dark triangle with strange strobing lights seen south of bend Oregon 21 mach 22:30 PST moving slowly at first then acelerating to the SIwas sitting out in my hot tub looking out at the north star (poloris) when i noticed what I though was a slow low flying aircraft with strange lights.the lights seemed to all be strobe like with a very high rate of cycle.the colors included the following blue green red bright white and orange. the lights seemed to be in a cross shape changing to a x shape then a straight line amidships with a faint line of red and with strobes along the back of the craft it was heading SSE from the north star through the cup of the big dipper.as the craft past the big dipper it was back lit by the stars at that time I grabbed my small 8x vivitar monocular and looked up at the craft. I could clearly see a dark black triangle shape with a curved stern this craft had to be at about 12000 ft since I am at about 4200 ft here.there was no sound and it was moving very slowly all of the sudden,the lights quit strobeing and a strait line apeared amindships and it doubled and the tripled its speed without a sound and disapeared to the SSE in less than ten seconds.