solid light traveling horizontally across horizon which grew very bright and disappeared.I'm an architectural designer, a private pilot who is building my own kit aircraft, President of the local Experimental Aircraft Association chapter 334 and formerly an e-4 US Air Force Missile maintainence technician for the Minuteman III and nuclear ground launched cruise missile systems. My wife and I love to sit in our hot tub and watch the aircraft, shooting stars and satellites go by. One night in early July we were watching some aircraft along the airway (providence to NY which runs northeast to southwest, slightly south of us)with all their lights on and strobes flashing. We both noticed a light of normal brightness and size east of us (somewhere over Rhode Island)traveling across this path to the southeast. This white light didn't have any nav or strobe lights around it. It was traveling horizontally just above the horizon to our right and away from us in a slight climb when it became very bright for a couple of seconds and disappeared. It was traveling about the same speed as the other aircraft 250mph+/- and way too slow to be a shooting star. Definitely not fireworks either. I know aircraft and this was not conventional behavior. The brightness was like that of a typical white taillight and then a landing light being turned on and pointed exactly at you - very bright. I'm sure that is not what it was - no aircraft could turn around that fast point at us and still travel along its path backwards. And when I say it disappeared, I mean nothing left of it. Also, no sound. We could hear the other aircraft that night.