I was at a friends house, we went into the back yard. It was between 9:30 and 10:00 pm. It was not completely dark out yet but dark enough that stars could be seen. My friend went back into the house to get a drink, I was looking up at the stars. I saw movement to my left so I looked up, thinking it was a commercial jet, and could see the craft coming from the north flying very fast. I watched as it flew overhead, it was flying as high as jets. It appeared to be huge, it was boomerang shape, it was grey in color and appeared to be translucent at times. it had dark circles underneath it, and looked like it had smaller circles on the leading and trailing edges. I saw no lights at all, no collision lights flashing like on jets or any illumination. It made no sound and there was no contrails. It flew in a straight line. I watched it for about 20 seconds before it flew above the clouds to the south. My friend did not make it out in time to see it.