Null geodesics in the equatorial plane of rotating reflecting surfaces of different radii R and with spin a = 0.99. The radii correspond from left to right to 2.0, 1.5, 1.1, 1.01 and 1.001 times the radius r₊ an event horizon would have had. The impact parameter b ranges from −5 to 5 GM/c². The solid grey line indicates the surface and the dashed grey line the location where the event horizon would have been.