Why does the Earth have different time zones?
The Earth has different time zones because it rotates on its axis, completing one full rotation in approximately 24 hours. As Earth rotates, different parts of the planet face the Sun at different times. This means that when it is daytime in one region, it may be nighttime in another. Since the Earth rotates through 360 degrees in about 24 hours, every 15 degrees of longitude represents roughly one hour of difference in solar time.
To make timekeeping practical for travel, communication, business and daily activities, the world is divided into different time zones. The Prime Meridian at 0° longitude is used as the main reference point for calculating time differences, with locations generally gaining time as you travel east and losing time as you travel west. In practice, some countries adjust their time zones according to political boundaries, geographical needs and national policies, so time-zone boundaries do not always follow exact lines of longitude.
