On my job, I work with people around the world. Many of these people live in India. India time, or IST, differs from much of the rest of the world in that it is off by thirty minutes, instead of an hour.
In 1884, the Greenwich Meridian was internationally recognized as zero degrees longitude at the International Meridian Conference, based on solar observations in Greenwich, England by Nevil Maskelyne. Over the next forty years, the world would supplant their local mean times with approximate differences rounded to hours or half hours “ahead of” or “behind” Greenwich Mean Time.
Greenwich Mean Time was considered deprecated as an accurate source of time variations globally in 1972 due to the inconsistency of the Earth’s rotation. GMT was replaced with UTC, or Coordinated Universal Time, which is based on atomic clocks.
It is believed that India had two time zones and for the sake of unity, split the two down the middle to have one uniform time zone.
India is not the only country with a strange time zone, though. Afghanistan, Iran, Nepal, Sri Lanka, and Kabul also have strange time zones, differing by 15-30 minutes. Some states/provinces, like Newfoundland in Canada and South Australia have time zones different from the rest of their country. Saudi Arabia is even stranger yet. Apparently, the time is set on a daily basis, based on the sunset.
Read the Wikipedia article for more information on Greenwich Mean Time.
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