We saw a soundless, dimly-lit, fast gliding craft at midnight that was unlike any aircraft known.We were doing some backyard star gazing on a clear, moonless night when something caught our eye in the southern sky. It was on a trajectory course heading northeast and it moved unlike any other aircraft we've ever seen -- and we come from a family of aviators. It was low-flying, like a small plane (maybe 8000 feet), only faster, and completely soundless. It was dark, and had no lights on. The only way we happened to see it was due to 3 dim lights grouped together underneath the craft which were barely illuminated. It moved from one end of the horizon to the other very quickly, and we were stunned by what we had seen, as we do not know of any aircraft that could fly so low, have no lights on, and remain soundless. Definitely not a winged aircraft, either.((FOLLOW-UP COMMUNICATION FROM WITNESS))Aack! Please revise the date on my report from a minute ago. It was the 10th, not the 17th (obviously).((END))