Large Light Sighted Over Long Island NY

I'm posting this report about 15 years too late, but I still remember exactly what I saw, it is one of those moments in your life you replay over and over again so that you don't forget.  
I was young and very much into scifi and aliens. I would watch the sky after dinner for hours until my bedtime.  After a while I started getting away from doing so but one night while shooting hoops under the street light near my house, I saw a light. 
At first I thought it was a shooting star (which was weird to me because the area where I lived was very bright at night, i had only seen shooting stars at a beach or on the sound where there are no city lights around).  I was facing north watching the object fly horizontal high across the other houses, but yet still far below the majority of the stars in the sky. 
It flew west to east as i watched it almost as if it was a train on a track. 
Then about 20 seconds into the sighting it started flying northward and continually got smaller and smaller.  I want to stress that it appeared to be flying slowly like a plane does at a high altitude, but this wasn't high and it changed its heading on a dime.  
It also appeared to speed up greatly once it made its northernly course.
 I want to include that this sighting was long before the Flight 800 tragedy, but i've heard that some people think they could be related.
Witness indicates that the date of the event is approximate.  PD