A small gray ball moved past my bedroom window on the 15th floor of a New York City apartment building.

I was four years old and had just been sent to bed by a babysitter. I didn't feel like sleeping so I knelt in my bed and leaned on my windowsill looking out at the city. Almost at once there was a small dark gray or possibly metallic ball moving steadily past my window. It was about 8-10 inches in diameter and had no distinguishing features at all. There was no sound or light associated with the ball. It was probably about 6-12 inches away from the side of the building and moved from left to right, which would have corresponded roughly to moving north. Our apartment was on the 15th floor and the window faced west-ish. (It faced in the direction of central park from the east side which is roughly due west.) The ball was not moving very quickly and I remember thinking that if I ran I would have time to get my babysitter to show her the ball before it had moved past the window. Which I did but of course when we got back to my room it was gone. I hadn't anticipated the time it would take to find her and convince her to come to my room.
Witness indicates that date of incident is approximate.  PD