To mark the clocks going forwards at the weekend, here are a few oddities on the subject of time zones. Working off GMT (also known as UTC or Coordinated Universal Time), here's some time zone things you probably didn’t know.
The biggest country in one time zone: China keeps things simple. It might have an area of nearly four million square miles, but ask each of its 1.4 billion residents for the time and you will get the same answer (it’s GMT+8). The same is true of India, the whole of which observes GMT +5.30.
The most time zones in one country: France takes this title on a technicality. True, all of metropolitan France sticks with GMT +1. But once you’ve added all those overseas departments the time zone tally rises to a remarkable 12. The sun never sets on France!
Russia and the US come a close second. Russia, the world’s largest country by area, covers 11 consecutive time zones (but since 2011 has only used nine), from the Kaliningrad Oblast (GMT+2) to Kamchatka, a vital component in any successful game of Risk (GMT+12). The US also uses 11 (five on the North American mainland, the rest made up of island territories).
The quickest way to lose 3.5 hours: No, not a colossal drinking session, just a quick hop across the border from Afghanistan to China. The two nations share a 47-mile boundary but are three-and-a-half hours apart. Not that anybody recommends travelling from China to Afghanistan. The next best option? Pakistan and China share a border, which can be crossed at the Khunjerab Pass, and have a three hour time difference.
How to gain an entire day: The International Date Line roughly follows the 180° line of longitude, which splits the Pacific in two. Fancy two birthdays in a row? Celebrate in Samoa (GMT +13). Next morning, take the 30-mile flight to neighbouring American Samoa (GMT -11) and - 25 minutes later, having crossed the International Date Line - land on your birthday again. Travel in the other direction if you want to skip Christmas.
Halves and quarters: Some nations are just out to confuse you. While most countries use time zones that differ from GMT by a number of full hours, others use half hour offsets. Such as India, parts of Australia, Sri Lanka, Newfoundland, Iran, Myanmar and North Korea. Even more curiously, Nepal and the Chatham Islands of New Zealand use GMT+5:45 and GMT+12:45, respectively.
The time on the South Pole: Longitudes converge at the poles, so neither North or South has an official time zone. But those scientists need to set their watches to something. In the North Pole, research stations follow the times in their respective countries, but the US-run Amundsen–Scott South Pole Station, uses New Zealand time. Why? Because all flights to Antarctica’s McMurdo Station depart from Christchurch meaning all official travel to and from the South Pole goes through New Zealand.
The time in space: The International Space Station follows GMT. Victory for Britain. Because when you’re orbiting the globe, it just makes sense.