Low flying, fast moving, absolutely silent reflective orb, no clouds, broad daylight.

Walking south easterly along a gravel path in Crown Hill Park. 90+ degrees, not a lot of people in the park and none in that area at the time. Orb approached flying north, probably about 5 degrees out of dead on toward me, going slightly toward my left. I stopped walking to watch it. It was moving much faster than planes or helicopters normally seen in the area. While it was moving too fast to be at high altitude, it was absolutely silent. Seemed like at most 1000 feet up. Plainly visible as a reflective orb. Kept waiting for more details to emerge as it neared me. Then it turned in an arc toward the west, then southwest. It came pretty close, I am sure it was over the park, but it never made a sound and never changed it's shape. No details ever emerged to indicate it was anything other than an orb. Looked metallic due to the reflectivity. As it was flying away I started walking again -- glanced toward the path and when I looked back the sky was clear, the orb was gone which I thought was jarring since it would have had to significantly alter its speed to be gone that quickly. About 40 minutes later a plane flew over that I thought might be around the same altitude. The plane was a twin engine fixed wing, very loud of course and very clearly a plane and very much slower than the orb. If the plane and the earlier orb were about the same height, the the diameter of the orb would be about the size of the plane's cockpit, maybe 10-12 feet.