Final answer:
The earth's rotation on its axis provides the basis for our system of local time and time zones.
Step-by-step explanation:
Eath Motion and Time Zones
Our system of local time and time zones is based on the earth's rotation on its axis. The earth rotates once every 24 hours, which means it completes a full rotation of 360 degrees in that time period. Time zones are established roughly every 15 degrees of longitude, so that local times correspond to similar hours of day and night. This system ensures that the sun is generally overhead at noon in every time zone that follows the 15-degree-wide system.