Before it disappeared, the best way I can describe is it sort of sputtered in brightness as it lost a bit of altitude at a steeper angle (otherwise went in a straight line up to that point) - appeared to slow down and dim but could have easily just been blurring because the big bright light turned into several smaller ones. Again hard to say because I had to idea what I was seeing and thought the aliens were coming or something - it sort of appeared out of nowhere in a flash
