Seen late christmas eve 2015 or 2016 in the backyard of my residence at the time. first sounded like small plane flying too low, but it got very much louder than a small plane and the engine didn't have the same kind of rhythm that a small plane does. it came into view as it crossed across my western neighbor's yard, moving slowly, cruising, really, quite near the treetops and power lines. wsw to ene. it was close enough that i could see clearly uniform, horizontal ridges on the "belly." the points of the triangle were clipped; headlights were mounted flush within the wings and nose. there may have been a few running lights on the belly. it moved steadily without changing speed across the sky; i watched it until it disappeared behind the eastern treeline. i initially thought it was a very large drone, not really knowing what a drone looked like, and told friends what i'd seen. i began looking for photos of drones, personal and commercial/military, and realized it likely was not a drone. over the years, i continued to look for images that might resemble the aircraft that i'd seen, without success. for a lark, i searched for ufo images and found images that looked very like the object that flew over my yard.