I barely visible dark boomerang glided across the sky noiselessly. No lights.

My sister and I went outside to have a small fire in her fire pit. It was already very dark outside so that we needed to use flashlights to get situated. Once the fire was started I sat back in my Adirondack chair and looked at the night sky. A few stars were visible but I immediately noticed that it looked like the sky was rippling. I looked closer and let my eyes adjust. It looked like a black boomerang was blocking the stars behind it, darker than the sky around it. As I stared I said, “What is that?” And my sister, apparently not seeing what I was seeing yet, said, “It’s an airplane.” I said, “OK” but kept staring intently. She saw this and looked to see where I was looking. She suddenly stood up and said, “What the hell?” I stood up with her and we continued to watch the shape. It had no lights of any kind and there was so sound coming from its direction. I don’t know quite how to describe this but it seemed to glide rather than fly. Maybe it was the speed it was moving at? I’m not sure. From the time I spotted it to the time it disappeared from our sight was probably 30 seconds. It didn’t appear to be as high as a jet would be or as low as a small airplane. It was somewhere in between. It was large. I would guess that it was as large as a passenger jet but, again, there was no sound. After it was gone we paid attention and we could hear jets up high and planes lower. We can’t explain this. If there was a trail it was too dark to see it. As far as we could tell we were the only ones who even noticed its presence. It was very stealthy. It was almost invisible but I don’t know how it would evade the radar of the nearby small airport.