Having a cigarette at work 8pm, Steeles and Martin in Milton Ontario. The sky was turning reddish dusky, scattered clouds. Im an aviation buff so was looking at an aircraft flying south of my position, west to east when I noticed an aircraft moving from East to West below the clouds. I thought it strange because it seemed quite close because the three or four brilliant white pulsating lights were moving as one but occupied 2/5ths of the quadrant of viewable sky(trees on either side). As it was reaching the middle if my view I payed close attention to ascertain a shape but could make none out. Just a row of lights. I could hear nothing. Without a doubt, the aircraft should be enormous and it must have been the size(based on distance between the first and last blinking lights) that aroused my curiousity because it was too close and too low.It took a few seconds before I was confident enough that this was not a typical aircraft then I yelled out to a colleague. He came running. We saw only white lights(typical only of approach lights). The aircraft seemed to get smaller, rapidly. The white lights pulsating in no order. It was now flying away from us, southwards towards Burlington Sort of weaving right to left until, in the space of 20 seconds, it was as far away as 50-60kilometres. (only an estimation based on the initial proximity and apparent length) We both agreed the speed must have been phenomenal. I am willing to describe if contacted but not comfortable giving contact details.All my distances are only guesses. The order in my description as scattered as my present frame of mind. We are directly below a point where large commercial aircraft begin approach to Pearson airport and a few kilometres from Burlington Skypark where small aircraft also fly. Two of my colleagues are private pilots and we are always planespotting. As a background, my family are aviation employees. I fly simulators as a hobby and have flown CAE's airbus and shortly the crj. I also fly RC planes. In short, unless this were a squadron of military aircraft, I would be stumped to come up with an explanation.