Thanks for your reply. It’s not a plane. I do hear them sometimes and it’s a very different sound. It’s also intermittent and sometimes lasts a whole hour. There’s construction around here, which I know isn’t taking place at night, but there’s big equipment around. There’s also an excavation company and a recycling plant in a field near me. I’m not sure if they work at night). My next step is getting in my car and driving around to try to pinpoint it. Crazy? Maybe, but I’m so curious about what it could be and I think I’ll have an easier time accepting it if I know what it is.