Simple crater model (left panel) and features in the asteroid that affect the total YORP torque (right panel). In the left panel, the yellow arrow represents the light coming from the direction of the Sun, and the shadow region is shaded in gray. Parameters h and R₀ are the depth and radius of the crater, respectively. The edge circle of the crater on the ground level is denoted by C. The angle between the sunlight and ground normal is denoted by λ₀. The right panel shows the boulders and craters on the surface of asteroids that could contribute to the total YORP effect.