Why time zones are stranger than you think

The idea is simple enough: the Earth turns once a day, so divide it into 24 slices an hour apart. The actual map of world time is nothing like that, because time zones are political objects rather than astronomical ones. Every deviation was somebody's decision.

Where the grid came from

Before railways, every town kept its own solar noon and nobody minded, because nothing moved fast enough for the difference to matter. Trains broke that: a timetable needs two distant places to agree what time it is.

Standard time zones were proposed in the 1870s — the Canadian engineer Sandford Fleming was among the most persistent advocates — and the International Meridian Conference in Washington in 1884 established Greenwich as the prime meridian. Adoption then took decades, country by country, and several never adopted the tidy version at all.

China: one zone across five

The most dramatic deviation on the map. China spans roughly 60 degrees of longitude — geographically five zones — and runs the entire country on a single one, UTC+8, set to Beijing.

The practical effect is severe at the western end. In Kashgar in Xinjiang, some 3,000 kilometres from Beijing, the sun in midsummer can still be up well past 10pm by the official clock. Local unofficial timekeeping runs two hours behind the national standard, so in practice two times circulate and you have to know which one an appointment refers to.

Russia: eleven zones and a reorganisation

Russia takes the opposite approach, with eleven zones — more than any other country. It has also changed its mind repeatedly: zones were consolidated in 2010, partly restored in 2014, and permanent "winter time" was adopted in 2014 after a brief and unpopular experiment with permanent summer time.

The countries that are not on the hour

India runs on UTC+5:30, a single half-hour offset for the whole country, chosen as a compromise between its eastern and western extremes. Sri Lanka uses the same. Iran is at +3:30, Afghanistan at +4:30, and Myanmar at +6:30.

Nepal goes further and is the only country in the world on a 45-minute offset, UTC+5:45 — set so that the meridian through a mountain near Kathmandu defines national noon, and distinct from India's by exactly a quarter of an hour.

Two more 45-minute zones exist below national level: the Chatham Islands in New Zealand at +12:45, and a part of Western Australia that keeps +8:45 unofficially.

Spain's inherited hour

Spain sits almost entirely west of Greenwich and keeps Central European Time, an hour ahead of the sun. The change was made in 1940, aligning Spanish clocks with Berlin, and was never reversed.

The consequence is a national schedule that looks strange from outside and makes sense once you know: late lunches, late dinners and late television, because the clock is running roughly an hour ahead of daylight. The same logic applies in France, which also sits mostly west of the meridian it does not use.

Moving the date line

The international date line is not a straight line and not fixed. It bends around territories that would rather not be split by it, and it has been moved deliberately at least twice in living memory.

Kiribati spans a huge stretch of the Pacific and used to have the line running through the middle of it, so that two parts of the same country were on different days — an obvious administrative nuisance. In 1995 Kiribati shifted the line east to enclose all of its islands. A side effect was that its Line Islands, at UTC+14, became the first inhabited place to enter each new day, which the country used to considerable effect at the turn of the millennium.

Samoa did the reverse in 2011, jumping westward across the line to align its working week with Australia and New Zealand rather than the United States. It skipped 30 December 2011 entirely — a date that simply did not occur there.

France has the most zones

Counting overseas departments and territories, France spans twelve time zones, more than any other country — a consequence of holding territory in the Caribbean, the Indian Ocean, the Pacific and South America.

Antarctica, where the rules break down

At the South Pole every line of longitude converges, so solar time is meaningless. Research stations instead use whatever suits them, usually the time zone of their supply line: the Amundsen–Scott station at the pole runs on New Zealand time, because that is where its flights come from.

And the smaller oddities

Newfoundland uses UTC−3:30, a half-hour offset from the rest of Atlantic Canada. Arizona does not observe daylight saving, except that the Navajo Nation within it does, while the Hopi Reservation within that does not — producing a small area you can drive through and change clock convention three times.

None of this is on a standard world map, which is part of why time zones are such a good demonstration that political geography and physical geography are different subjects. If you want to test the physical half, the map quiz and the guide to map projections are the places to start.