Copper sphere sighted over Jersey City . Sphere maintains consistent altitude.The sphere was approx 2-3 feet in diameter ( an estimate based on its visibility in reference to the Chase building about a half-mile away and its relative size in comparison with Chase's satellite dishes) . The sphere was of an unmistakeable copper finish. It was not emitting light but reflecting it. It turned black & shadowy on its lower half intermittently giving an impression of undulation. It flew a straight and consistent flight path SW-NE maintaining altitude of about 300 feet. Its trajectory and path was too straight for a balloon to maintain for the duration that I witnessed. It made no sound.