Black, changing shape from circular to elliptical, no noise, no lights, moving WNW over Turin.Watching aircraft approaching Turin airport at approx 21.35 from the balconey of my apartment, as this went from view to my left, I noticed approaching from the WNW from above the alps, what appeared intially to be a black dot, but as I watched, it seemed to changed to a more elliptical shape, at which point it looked head-on like a fighter, but no lights, and still black.I continued to watch this shape approach, and it continued to change shape, cycling from circular to elliptical, still black, and no lights. It passed almost directly overhead to the right of my apartment, then went from sight over the hill behind my apartment.It was impossible to judge altitude. Just prior to it going from sight, a BA146 jet approached Turin airport virtually in the opposite direction, guess this was around 4000/5000 ft, heard it's engines etc, but as this went from view, I watched the ufo for another 10/15 secs, completely silent, and no lights, still changing shape.The only analogy I can draw, is the changing shape of asteroids, as dipicted in say documentaries etc, BUT, outside shape was well defined, not ragged.It was a very clear evening, with light blue twilight, and the alps were clear as a bell, some 30/40 miles away. I made a page of notes immediately after the sighting, these are available to be faxed, and marked on a map the direction WNW.