7:40 pm after Christmas dinner, took dog for a walk and was admiring the stars on a perfectly clear crisp night when a large triangular craft with dim, diffuse red lights flew directly over me at low altitude. It was hard to gauge the exact altitude but I estimate between 1000-5000 ft and the size of the craft was of the order or larger than a 747. The distance between the lights was roughly thumb to extended index finger at arms length. It moved completely silently in a straight line due west over the bay towards Delaware. The lights were continuous and not blinking and were diffuse, almost as if behind clouds; however, there were no clouds that night. It moved quickly and at a constant speed, likely subsonic but by the time I got my phone out to try to get a video it had gone under the treeline. Covered my 90 degree view of the sky in the time it took me to get my phone out and switch to video. Other air traffic was visible at higher altitudes and were clearly airplanes, this triangular craft was unlike anything I have ever seen. It was not a helicopter, airplane, drone, satellite, balloon, planet or star. I have a PhD in aeronautics and astronautics (plasma focus), am an avid star gazer, and am confident in my ability to identify various aircraft, this sighting shook me.