Not a UFO, but very strange...At approximately 8 pm last night, while grilling on my back deck, I noticed four airplanes flying due north in a straight line, directly over my house, at an estimated 5,000 to 7,000 feet. These were large commercial jets, likely 737s or larger, and from my vantage point were separated by no more than one mile.While we live smack-dab in the middle of a very busy air-traffic corridor, we never see commercial planes traveling this due-north trajectory (instead, most commercial jets pass over us at a lower altitude, heading west on final approach to MacArthur or Kennedy airports). And these planes were VERY close together -- as I said, no more than a mile between the first and fourth in the line, and probably less than that.In fact, the third and fourth planes almost seemed to be jockeying for position, racing extremely close to each other before falling into line. Worthy of note: All four appeared to have their anti-collision lights on full and were very bright.I suppose my eyes could have deceived me; this could have been a military formation heading north toward Connecticut, or perhaps the planes were not as close together as they appeared. But I've lived near major airports my entire life, and I believe I can identify commercial airliners; I also believe they were traveling at the same approximate altitude, and most certainly the same speed.My 6-year-old son also witnessed the jet formation.I noticed a triangular UFO was reported last month in Riverhead, which is our town here on Long Island (Wading River is our hamlet). I doubt that report was related to this event, and these planes did not appear otherworldly in any sense. But it was very, very strange to see commercial jets flying like this, and I thought it was worthy of mention.