The earth has two motions – it spins on its own axis and it orbits around the Sun. Its rotation about an axis causes the rising and setting of the sun, moon, and stars and the changes from day to night. One complete turn of the earth actually takes 23 hours, 56 minutes, and 4.091 seconds. There are tiny variations because of the friction of ocean tides and the changes in the earth’s crust.
The earth also moves around the sun and at some points it is closer to the sun than at others. The earth and all planets move in their orbit at a speed that depends on the distance they are from the sun. A planet moves faster when it is closer to the sun than when it is farther away. The orbital speed varies therefore between 18.8 miles per second to 18.2 miles per second.