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Longitude is an important concept when it comes to understanding how our world is divided into time zones.
It represents the geographical coordinate that specifies the east-west position of a point on the Earth's surface.
Longitude is measured in degrees (°), and the prime meridian (0° longitude) runs through Greenwich, England.
It divides the Earth into the Eastern and Western Hemispheres.
As you move east or west from the prime meridian, the longitude increases up to 180°.
This system allows for precise time calculations as the Earth rotates every 24 hours.
Travelers often change their watches based on changes in longitude to reflect the correct local time.

The Earth rotates 360 degrees in 24 hours, which makes calculating time changes straightforward.
To determine how many degrees the Earth rotates per hour, you simply divide the total degrees by the total hours.
This calculation looks like this: \( \frac{360^{\text{°}}}{24 \text{ h}} = 15^{\text{°}} \text{ per hour} \).
This means that for every hour, the Earth rotates 15 degrees of longitude.
This is why, on average, if you travel 15 degrees east or west, the local time will differ by one hour.
This constant rotation rate is crucial for understanding and calculating time zones.

Understanding time zones and calculating time based on longitude are essential skills for travelers and anyone dealing with international schedules.
Using the degrees per hour concept, you know that a 15-degree change in longitude corresponds to a 1-hour difference in local time.
So, if you travel from a location at 0° longitude (Greenwich) to a location at 15° east longitude, the local time advances by one hour.
Similarly, traveling west will set your clock back by one hour for each 15-degree difference in longitude.
This allows us to logically and easily determine the local time when moving across different parts of the Earth.
Accurate time calculation is not only convenient but crucial for coordinating international activities, meetings, and travel plans.