"The UFO would simply appear, and within hours be gone again. It was dark and perfectly round from beneath, but otherwise featureless, formless and silent. Jack never witnessed it’s coming or its going. He would sometimes try to throw a rock up at it, but no matter how hard or precise his pitch, the rock would always fall back to the earth in a slow, inexorable arc. Was it even truly there? Birds skidded above and below it in the surrounding blue. Stars in the night were extinguished upon its knife-edge of curved black. It existed, as surely as did the ground beneath his feet.
Nevertheless, nobody could see it but Jack."