How are time zones determined?
Time zones are determined by dividing the Earth's surface into 24 longitudinal segments. The primary method used to establish time zones is through the concept of the Prime Meridian and the measurement of longitude.
The Prime Meridian, located at 0 degrees longitude, serves as the reference point for timekeeping and the starting point for determining time zones. It passes through Greenwich, London, and is commonly known as Greenwich Mean Time (GMT) or Coordinated Universal Time (UTC).
The Earth completes one full rotation every 24 hours, resulting in 360 degrees of longitude. With each degree of longitude representing approximately four minutes, dividing 360 degrees by 24 hours gives us 15 degrees per hour.
Starting from the Prime Meridian, each time zone is typically defined as a 15-degree longitude range. As one moves eastward, the time advances by one hour for each time zone, while moving westward results in the time being set back by one hour per time zone. The actual boundaries of time zones may deviate slightly from the 15-degree intervals to account for political, geographical, or cultural considerations.
International agreements and conventions, such as the International Meridian Conference held in 1884, have significantly established the standardization of time zones across different countries and regions. Countries adopt specific time zones through these agreements to ensure consistency and facilitate global coordination.
It's important to note that some regions or countries may choose to deviate from the standard time zone boundaries for various reasons, such as aligning with neighboring regions, maintaining a consistent time within a political or economic union, or considering geographical factors.