Johnny was looking for fireflies in the dusk. Suddenly there was a whooshing noise like a rushing wind, and something that spun like an enormous top loomed overhead. It was a pale blue and it blended in with the color of the night. It was as wide as the side of the barn and nearly as tall as the haymow door. There was a humming in Johnny's ears. For an instant he was afraid. Then he was not, because he knew what it was. Dad had been talking at dinner about things like this. It was a flying saucer!
Used availability for Carl L Biemiller's The Magic Ball From Mars