I was stargazing [in a rural community in the approximate middle of mason county] at about 8:45pm, in a northerly direction, when in the eastern sky at about 40 degrees elevation above the horizon, i noticed an object in the sky moving at a relatively fast pace, faster than any terrestrial aircraft i've seen [other than fighter jets in pursuit of something], at an elevation higher than i've seen commercial aircraft fly. this object was roughly round, glowing silvery-white but with no functional lighting on it that a terrestrial aircraft would have, and it generated no sound. it was moving in a northerly direction, and after about a minute it changed direction 90 degrees to its left, the direction change took about 10 seconds. it stayed in this new orientation bearing northwest, for about 30 seconds, then swung back to its right, in a north direction, taking about 10 seconds to change direction. at its height, it was at an approx. 70 degree angle relative to the ground, before disappearing near the horizon behind some trees. at the same time, a regular propeller aircraft with its red lights visible, flew underneath of it at an estimated relative distance [underneath the ufo] of at least a mile, flying to the northeast. the sky was clear and relatively free of smog, on the far end of twilight. since i live in a rural area, of course there were tall trees i had to steer around to maintain my view of the sky objects. until i lost the objects behind some of the aforementioned tall trees at the horizon, i followed the sky objects with a pair of 7x binoculars, and found the objects just noticeable with the naked eye. i thought to myself that this sky object [not the airplane] didn't behave like a satellite nor did it behave like any terrestrial aircraft i'd seen up to this point. i'm guessing the whole thing took no more than 3 minutes, start to finish.