Time zones

Time zones are a series of 24 sections or partitions into which the Earth is divided, using the Greenwich meridian as a reference . It is an effective way to calculate the time in each region of the planet, which is extremely important because for a few good years financial transactions and the transport of materials and people around the world is normal. The name of spindle comes from the textile world, because it is precisely the element with which it can be spun; an analogy that can be understood with the image of time zones on a planetary scale.

What is a time zone?

The definition of what a time zone is starts from the assumption that the earth has a spherical shape and that in 24 hours it produces a complete rotation of 360 degrees on its axis. If the degrees are divided by the hours, the 24 segments of angular amplitude of 15 degrees that are covered in one hour are obtained. The time zones are the 24 sections into which the earth is divided, taking, as we said, the Greenwich meridian as a reference. Each time slot has a specific time assigned that applies to towns that share the same meridian.

What is the function of time zones?

The time zones refer to the 24 sections in which the planet is divided, by a meridian and in which the same time rules by convention. But why are there a total of 24 sections? The calculation is quite simple: the earth is an oblate spheroid, that is, it has a total of 360 degrees, which results in each time zone measuring 15 degrees, since the mentioned total is divided by 24, the number of hours that it takes the Earth to turn on its own axis and that it is the measure of one day on the planet. Then, the 15 degrees represented in each time zone represent one hour, calculated according to the east or west direction from the reference meridian, which is Greenwich, in the United Kingdom.This is how it can be summed up: 24 hours a day correspond to the 24 zones in which the planet is partitioned.

But what is the function of this human artifice based on planetary geography? Very simple: organize time on a global scale or even, in a somewhat pompous way, create world time. It is that previously time was configured from different meridians according to the authorities of the country or place, which was very impractical if links of any kind were generated with other more or less distant sites. With the system of zones, the time measurement of the 24 zones is governed from the reference to the zero meridian: the calculation is simplified and made global.

This coherent system of time, starting from a single point of reference, was the product of the final years of the 19th century and its inventor was the Scottish-Canadian engineer Sandford Fleming.

How to calculate time zones

The 24 time zones are governed by a standard or time pattern called UTC (Coordinated Universal Time), which in turn is obtained from International Atomic Time, another scientific standard that measures time in atomic clocks located in diverse points of the planet and whose result is a greater precision. The latter yields two curious facts: time is not governed by astronomical data in terms of its unit, which is the second, and this method is more effective because, in truth, for multiple causes, the Earth’s rotation is not uniform.

Ergo, the planet’s time zones are calculated using a unique reference: the zero or Greenwich meridian. From the zero meridian to the east an hour is added to the home zone according to the standard; and those that are from the meridian of Greenwich towards the west one hour is subtracted from each one. The explanation for all this lies in the fact that our planet rotates in the direction from west to east. Positive deviation is the name given to the calculations of the spindles that run through the direction of rotation; negative deviation to the calculations in the opposite direction (to the west).

Time zones: map

The map of the time zones is not only ideal to observe how time is calculated on a planetary scale from the reference to the zero meridian, but also indicates how a large number of countries, with longitudinal development, can have more than one time zone. schedule. Possibly, the outstanding cases are nations such as Russia, Canada, the United States, among others.

Time zones: examples

If we know your time zone, we can easily and quickly calculate the time in a specific region or city. It is important to remember that if the zone is in negative it means that the hours are subtracted; and if it is positive, they add up. Here are examples.

The time of a place is determined on the basis of UTC (Coordinated Universal Time or Coordinated Universal Time) of Greenwich. For instance:

Rome: UTC + 1, this means that if it is 12:00 UTC (for example, in London), in Rome it is 13:00
Los Angeles, California, USA: UTC-8, this means that if it is 18:00 UTC, so it is 10:00 in Los Angeles
Mumbai, India: UTC + 5.5, which means if it is 10:00 UTC, in Mumbai it is 15:30

When the time zone setting results in an hour past midnight, the local date is changed to the next day.

Some examples:

Cairo, Egypt: UTC + 2 (i.e. if it is 23:00 UTC on Monday, March 15, Cairo time is 01:00 on Tuesday, March 16)

Auckland, New Zealand: UTC + 12 (i.e. if it’s 21:00 UTC Wednesday June 30, Auckland time is Thursday July 1 09:00)

When the time zone setting is one hour before midnight, the local date is changed to the previous day. Some examples:

Buenos Aires, Argentina: UTC-4 (that is, if it is 03:00 UTC on Saturday, July 23, the Buenos Aires time is 23:00 UTC on Friday, July 22)

Honolulu, Hawaii, USA: UTC-10 (that is, if it’s 6:00 UTC on Monday, May 1, Honolulu time is Sunday, April 30 at 20:00)

In some cases, due to daylight saving time (which is not used in all countries) a time zone adjustment is made. Example

New Zealand: UTC + 12 , observes a one hour adjustment due to daylight saving time during the southern hemisphere summer, resulting in a local time of UTC + 13.

For the polar regions , a time corresponding to UTC for the North Pole and UTC + 12 for the South Pole is conventionally adopted.