SC.4.E.5.4 Earth’s Rotation

SC.4.E.5.4 Relate that the rotation of Earth (day and night) and apparent movements of the Sun, Moon, and stars are connected.

What is the Effect of the Earth’s Rotation on its Axis?

‘As the Earth rotates (spins) on its axis, the objects of the sky appear to move across the sky. In the morning, the Sun appears to rise in the east, move across the sky, and set in the west. At night stars fill the sky, also moving from east to west. The moon is visible sometimes at night, sometimes in the day, and sometimes not at all. When it is visible in the sky, the moon also appears to move across the sky.

All these apparent motions are caused by the rotation of the Earth on its axis. The word apparent comes from the word appear: these objects appear to move across the sky. You do not feel the movement of the Earth because you are moving along with it. The Earth is so large, compared to you, that you do not directly sense this motion. You can see this motion as the Sun, moon, and stars move across the sky. It is hard to notice these objects appearing to move across the sky. If you have ever watched the Sun set, you may have been able to notice its motion as it approached the horizon and then sets.

 In this illustration, we can see the Sun at the center of the Sun-Earth-moon system. The other planets are not shown in this illustration. The Sun is the star at the center of the Solar System. The Earth, like all planets, orbits the Sun. The movement of the Earth around the Sun takes 365 days, or one year. As the Earth revolves around the Sun, the patterns of stars in the night sky change. The Earth rotates on its axis once every 24 hours. This rotation is the cause of the apparent motion of the Sun across the sky. The Sun rises, moves across the sky, and then sets. The next morning it rises again. This cycle of rotation happens every twenty-four hours, or one day. We can also see that the moon travels in an orbit around the Earth. All moons orbit a planet. The length of time for the moon to orbit the Earth is 28 days, or just under a month.