On my mom's back porch in Harleysville, PA we saw a boomerang shaped object about 200 yards above the yard coming towards us.It literally came out of nowhere with two bright lights almost like a huge car with headlights driving right towards us. There were 3 portholes on each end of it (one on each end and one at the front point). This was moving extremely slowly and not making a sound. As soon as it was directly above the deck it made a sharp left turn (my right) and continued moving just as slow only now there was a deep, low pitched, quiet hum that would not have been audible from inside of my house. After it turned it continued until I couldn't see it due to trees blocking my view.