The most obvious starting place for this is to look at what causes our days and nights (the earth rotating on its axis once every 24 hours from west toward the east, so that the sun appears to rise in the east and set in the west), and therefore look at both the sun and the moon. The moon's apparent motion on the sky. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky. Earth rotates or spins toward the east, and that's why the Sun, Moon, planets, and stars all rise in the east and make their way westward across the sky.