GMT and IST

A time zone refers to an area on the globe that has a uniform standard time. It is employed by the people for their legal, social, and commercial purposes. Currently, there are numerous time zones on our planet where each of the groups of people/countries uses what seems effortless to them. They have the freedom to choose their time zones but within their boundaries. There are two most popular time zones in the world, namely Greenwich Meantime (GMT) and Indian Standard Time (IST). Both are used by respective countries of the world in measuring the time in their country at that moment. 

Greenwich Meantime 

Greenwich Meantime pertains to the solar time observed from the Royal Observatory in Greenwich, which is situated in London. You can also call Greenwich Meantime as the Universal Time Coordinate (UTC). 

Established in 1675, the Greenwich Meantime was used and created by the Royal Observatory for the sailors to determine the place in the sea with the help of the longitudes. One thing that was advantageous of this measure was that it helped the whole country to maintain a single reference time and thereby decide the locations of the longitudinal lines. 

Also known by the name of Prime Meridian, GMT helps in defining the time of the other places/locations based on this as the reference point. Notably, the Greenwich Meantime is present at zero degrees of longitude and others move degrees further and back from it. 

Indian Standard Time  

The Indian Standard Time (IST) is the time reference observed in two countries namely, India and Sri Lanka. Interestingly, this standard time runs five and a half hours ahead of the Universal Time Coordinate (UTC) or the Greenwich Meantime. 

The clock tower of Mirzapur with 25.15° latitude and 82.58 longitudes is considered the most important, due to this calculation for India’s time being made for the country. The nationwide acceptance of this time zone was made after the country got independence from the Britishers, in August 1947. 

Nevertheless, Kolkata and Mumbai didn’t accept this as their standard time till 1948 and 1955 respectively. After that, the whole of the nation started following and using IST as their Standard Time. Later those years, the Government decided to shift the central observatory to Chennai and made the standard time 5:30 hours more than the GMT. 

Difference between GMT and IST

Establishment

The Greenwich Meantime (GMT) is a well-known standard time used by various nations to calculate the time at their places. It was established in 1675 by the Royal Observatory with the sole purpose of assisting the people in the sea area so that they can locate places with the help of the location of the longitudes. 

On the other hand, the Indian Standard Time (IST) is the standard time accepted by India and Sri Lanka. The nationwide acceptance of this time zone was made after the country got independence from the Britishers, in August 1947. 

Calculation of standard time

The Greenwich Meantime is calculated based on UT1, which is the modern form of solar time present at 0° longitude. On the other hand, the Indian Standard Time (IST) uses the Mirzapur clock tower as the basis of all the time calculations made in the country. 

Issues with the standard time

There are certain issues with both the standard times. If we take the case of Greenwich Meantime, the issue that pertains there is that the noontime rarely syncs with what has been accepted. It has no match between the accepted standard time and when the Sun crosses the Greenwich Meantime. The reason behind such an issue is the uneven angular velocity of the planet which gives an axial tilt to it. 

On the other hand, the Indian Standard Time also has a similar issue where there is a noticeable difference between the daylight at various places in the country. Notably, there is a difference of about two hours between the Western and Easters parts of our country. You must know that India extends between the geographical coordinates from 68°7’E to 97°25’E, which gives a spread of about 29° in the country. 

Usage in different countries 

The Greenwich Meantime is used in the United Kingdom and various Commonwealth nations of the world including, New Zealand, Australia, and many other locations of the Easters Hemisphere of the longitudes. On the other hand, the Indian Standard Time is used in Sri Lanka and all of India. Nonetheless, there are certain references from the Universal Time Coordinates (UTC) as well. 

Adherence to the geographical expanse of a country 

In the case of Greenwich Meantime, we know that various legal, geographical and political criteria adhere to the measurement of time zones in an area. Thus, there is a possibility that we might face some discrepancies in the estimation of Greenwich Meantime. 

On the other hand, in the other case of Indian Standard Time (IST), we can infer that the use of IST isn’t enough to cover the vast and extensive geographical expanse of India. There is an apparent difference between the daylight at various places in the country. Notably, there is a difference of about two hours between the Western and Easters parts of our country. Nonetheless, the Government of India has decided to take various steps to overcome this problem.

Conclusion

With the existence of flaws in the standard time zones of the country, the Government has decided to take up various steps to retain the preciseness of the time zones in the country. In 2014, Assam Government even took forward a petition for the changes in the time zone in their area, but that hasn’t been approved by the Central Government of India. Early sunrises and early sunsets in north-eastern India have hampered their daylight hours and thus lowered the productivity of the labour.