Earth rotation refers to the spinning of our planet on its axis, which is an imaginary line that runs from the North Pole to the South Pole. This rotation takes approximately 24 hours to complete, resulting in the cycle of day and night. As Earth rotates, different parts of the planet are exposed to the Sun, causing daytime in some areas while others experience nighttime. The speed of Earth's rotation varies depending on the location. At the equator, the surface moves at about 1,670 kilometers per hour (1,040 miles per hour), while at the poles, the rotation speed is nearly zero. This rotation is also responsible for the apparent movement of the Sun and stars across the sky.