Solar disk discretized in five concentric rings from which we determine the actual visible solar disk ratio while considering solar limb darkening and obstruction by the horizon. The radius and area of each ring are denoted R_j and P_j, respectively. The points C_j are placed halfway between two successive radii except for the C₁ which is placed right in the center of the disk. In this example only the brightest, most inner ring of the Sun is completely visible. All other rings are only partially visible due to obstruction by the horizon.