My friend, our two 13 years old daughters and i were up north wisconsin in the summer, far away from major cities therefore sky was so clear and filled with stars, and we saw the sky from horizon to horizon, we saw couple airplanes and slow moving stars what we called as satellites. suddenly 4 of us saw two objects that looks like bright stars were going from east through the sky with extraordinary speed like one "star" was chasing another and very close to each other on visual field of sky about 1 inch from each other, then when they approached about middle of the sky or right above out heads, first one without slowing it's speed made about 90 degree turn and one that follow it just stopped right in the center of our visual field. first "star" without slowing down flew to north side of the sky until we no longer can see it. we lost track of the second one as it stopped and mixed up among other stars. to give an estimate how fast they were going that entire event took about 10-13 seconds. i am physician and like to reading about technology and with certainty can say that there are no human made objects that can fly with such speed through sky at very high altitude, basically from horizon to horizon for about 10+ seconds, make 90 degree turn at such speed and especially make sudden stop from high speed path. four of us witnessed that event and we all were amazed and recollected about what we had seen. unfortunately as murphy law none of us were filming it, as we were fascinated looking at what we saw. although i thought about it but regular cell phone camera unfortunately is not sensitive enough to records movement of the stars.