UFO details report: At 11:35 am (approximately), I was out on the front porch smoking. I noticed an object to the east that seemed to be making a turn toward the west. I immediately thought it was a hawk, as we have a few of them in the area, that hunt along the 427 highway corridor. Bigger than most birds, they stand out as dark blotches gains the sky.It quickly became apparent that the object was not a bird, because as it turned, it appeared to become completely spherical.Once it had turned, it moved directly west, unwavering in it's course-- from my position, it looked as though it may be following the 401 westbound below the southern-most boundary with Pearson Airport.Object was dark grey, but appeared to be reflective. It may have had an aura surrounding it also, a very faint distortion surrounding the object that was intermittently visible.From my position, I would say that the object looked to be the size of a large drone-- not big enough to hold a person, but made no sound and moved at the cruising speed of a light-duty helicopter.My mind tells me I saw a drone, but my eyes saw no evidence of propulsion or armature to hold propellers. It appeared to fly without the aid of any outboard-mounted engine.I lost sight of the object roughly a minute after first spotting it, as it continued past the visible horizon through the rooftops in our neighbourhood.