driving to work one evening last week on route 16 heading east around 1115pm i see a wide body plane moving slow in my direction above. The plane appears to be a transport type cargo carrier maybe us military, not sure. anyway, it was a nite that i could keep my passenger window open. i do not hear loud engine noise only soft turbine rotation. the large plane in descending and turning. as i approach heading east about 45mph the plane apppears to not move much catching my attention. i thought is was a visual trick caused by moving in opposite direction the plane would appear to move slower than usual. this was a huge plane as it lowered and turned to the south.i got a birds eye view of what appeared to be a disc like cap below the nose of the plane. i looked closer in less than 10 seconds and could see a perfectly round disc attached to the underbelly. it looked like a lucite circle encircled by alternating bright white and black segments on the perimeter. i could see the lucite portion reflect ground light. the bright white light in the perimeter was intense halogen like.i thought maybe this is a military design i had never seen.afterthought is that was a disc attached to the underbelly just below the nose of the aircraft.time was disoriented during the sighting and that plane seemed to move too slow and there was hardly any noise such as when jets are shut down and a plane glides into landing.the nearby airfield would have been macarthur airport in islipother cars are on the highway at that time but really not many. maybe 5 total going in both directions.