This answer will extensively provide information about the Indian Standard Time (IST), the reasons for choosing a particular standard meridian, etc.
Reasons behind selecting Standard Meridian of India
- The time at the Central Meridian of a nation is considered as the Standard Meridian of the country to maintain uniformity of time to the best possible extent within the territorial limits of that nation.
- There is a standard practice among all the countries in the world that the standard meridian of the countries has to be in the multiples of 7°30′ of longitude.
- This is done so that the difference between Greenwich Meridian time and the standard time of a country can be expressed as multiples of an hour or half an hour. Hence 82°30′ E meridian passing through Mirzapur (Uttar Pradesh) has been selected as the ‘standard meridian’ of India.
- The time difference between Greenwich Mean Time and the Indian Standard Time is 5 hours and 30 minutes.
Need for more than 1 Standard Meridian in India
- There is a wide difference in local time of places located at different ends of India due to longitudinal extent of about 29° as India extends between 68°7’E and 97°25’E longitudes from west to east.
- The sun rises about two hours earlier in the east (Arunachal Pradesh) than in the west (Gujarat).
- For every one degree of longitude, the local time changes by four minutes, the difference between extreme two points of India would be about two hours.
Reasons for Rejecting more than 1 Standard Meridian in India
- Technically it is possible to have two time zones and two ISTs in India as per a scientific study.
- However, due to possible strategic reasons the former Minister of Science & Technology, Health and Family Welfare and Earth Sciences of India had rejected the idea.
- Those against more than 1 standard meridian in India have pointed out the possibilities of Railway accidents as time needs to be reset at every crossing from one time zone into the other.
Countries with more than 1 Standard Meridian
- The world is divided into 24 major time zones.
- Some countries due to its vast east-to-west extent have more than one standard meridian,examples are Russia, USA, Canada. There are 7 time zones in the USA.
- All countries of the world can choose the standard meridian within their territory to determine the time within their administrative boundaries.