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What is a time zone? -

Put simply, a time zone is an area of the Earth that has been sectioned off so that it follows the same time. The whole planet is divided into multiple time zones, and traveling from one zone to another means that time itself will change.

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Coordinated Universal Time (UTC) -

But how are time zones measured? You have probably seen something like "UTC+03:00" written somewhere. Basically, the Coordinated Universal Time (UTC) is the standard time used to measure all zones on the planet. The UTC is at the Earth’s 0° line of longitude.

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The middle of the map -

The 0° line is the line that divides the Western Hemisphere from the East. This line is called the "prime meridian," and it passes straight through the Royal Observatory in London, England.

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Adding and losing time -

The further you travel east or west, the more time you will add to the UTC, usually in hourly increments.

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An Earth divided -

Although the conventional understanding is that there are 24 time zones divided equally between both hemispheres, the truth is that there are actually 38. This is because some countries, like India and Nepal, are offset by 30 or 45 minutes instead of one whole hour.

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Communication -

Time zones tend to wrap around the borders of countries and their subdivisions instead of following longitude, because areas that frequently communicate with each other find it more convenient to follow the same time.

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The Sun is a clock -

For a long time before the creation of standard measurements of time, humans relied on the Sun to determine when to do things. Different locations would use different solar times, which would change depending on the culture or the angle of the Earth.

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Railway time -

In the 19th century, British railway companies started using timepieces called chronometers that were set to the prime meridian, which was known then as the Greenwich Mean Time (GMT).

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New Zealand time -

In 1868, New Zealand also adopted their own standard time, which is 11 hours and 30 minutes ahead of GMT.

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Too much time -

In North America, "railway time" was very problematic, since each railroad pretty much had its own standard time that was defined by individual companies.

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Dividing American railroads -

At the end of the 1800s, Charles Dowd (1825–1904) proposed that American railroads be divided into four hourly standard zones. But this proposal was never accepted by railroad companies.

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For the weather -

Afterwards, a meteorologist by the name of Cleveland Abbe divided the United States into zones that would help weather stations. He convinced railroad companies to adopt the system, which created a snowball effect.

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Standard time -

Congress formally adopted standard time zones in 1918, with the signing of the Standard Time Act.

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24-hour time zones -

But the worldwide time zones as we know them were actually introduced by an Italian mathematician named Quirico Filopanti. In 1858, he proposed dividing the planet into 24 hourly time zones. But, nobody paid attention to his proposal.

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The knight of time zones -

Almost 20 years later,  Scottish-Canadian engineer and inventor Sir Sandford Fleming proposed a system of time zones that was similar to Filopanti’s. It received some consideration.

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Worldwide influence -

By about 1900, nearly every populated area on Earth had switched to a standard time zone. But only a few of them used GMT as an offset.

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The last country -

It took many decades before all the time zones adopted a standard offset. The last country to do so was Nepal in 1986.

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Notable exceptions -

There are some countries that follow different rules to determine standard time. For example, even though the prime meridian passes through Spain, the country has a standard time of UTC+01:00.

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A single time -

Some countries, such as China and India, only use a single time zone even though the borders of their territories extend far beyond the area for typical time zones.

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French time -

France has the most time zones of any country in the world, with 12 zones. However, this includes the country’s overseas territories, pictured here.

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Russian time -

Russia, the largest country in the world, has 11 time zones. Two of its time zones were removed in 2010, but they were reinstated four years later.

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International Date Line -

The line over the Pacific Ocean that divides the Western and Eastern hemispheres is called the "International Date Line." Due to the location of some countries in the Pacific, the Date Line is not straight.

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To the West -

The westernmost time zone is occupied solely by the United States, with an offset of UTC−12:00. The only places that belong to this time zone are two islands: Baker Island and Howland Island. Both of them are uninhabited.

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To the East -

The easternmost time zone belongs to the Line Islands at UTC+14:00. Originally, the islands were placed on either side of the International Date Line. But in 1994, the line was moved more than 620 miles (1,000 km) to the east. This created the unique shape that you can see on maps.

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The more daylight, the merrier -

One reason that countries have drawn time zone boundaries far to the west is because it allows afternoon sunlight to be used more effectively before the Sun sets.

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Daylight saving time (DST) -

In some countries, daylight saving time is adopted during the summer in order to make use of the longer daylight. It involves advancing the clocks by one hour before summer, and then adjusting back in the fall.

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In outer space -

Spacecraft that orbit the planet cannot typically respect a 24-hour sleep-wake cycle, because the spacecraft may experience several sunsets or sunrises in that time. In particular, the International Space Station normally uses GMT.

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Mars -

On Mars, timekeeping is a bit complicated, since the planet experiences a solar day of about 24 hours and 40 minutes. Mars rovers have often been synchronized with the Martian day so that there is a balance between periods of light and dark.

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The Moon -

Recently, NASA has stated its intention to create a standard time on the Moon. That makes sense, considering how many planned lunar missions there are for the future. Perhaps humanity will build a colony there and it’ll be called Moon Standard Time!

Sources: (Smithsonian Magazine) (Time and Date) (Reuters) (CNN)

See also: Discover the summer island getting rid of time

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