Looked out window and saw the sun catching on a bright ball in the sky, it was round and fast. Moving horizontally.

Me and my mother were eating supper when I looked out the window and saw a big object in the sky. I thought it was a plane at first but then it was very fast. I got up from my seat after my mother and went to the window to get a better look. It was a silk white and sometimes shined gray, it moved horizontally, back and fourth quite fast. My mother thinks it was a eagle but I didn't see any wings or trail behind it. The sky today is clear with a few clouds.