A time zone is a region if the planet that observes a uniform standard of time for commercial, social and legal purposes. GMT and IST are two such time zones

Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London which is measured at midnight. In English speaking nations, GMT is often used synonymously with Universal Time Coordinate (UTC).

Indian Standard Time (IST) is the time zone observed throughout India. It does not take into account daylight saving time along with other seasonal factors. India has only one time zone.

*IST is ahead of GMT by 5:30 Hours.

Difference Between GMT and IST - UPSC 2021

In this article, we will examine the differences between the GMT (Greenwich Mean Time) and IST (Indian Standard Time). They both are recurring terms under the Geography segment of the IAS Exam.

Differences between GMT and IST

GMT (Greenwich Mean Time)	IST (Indian Standard Time)
The Greenwich Mean Time was established by the Royal Observatory in 1675 with the purpose of assisting navigators at sea.	The Indian Standard Time was established as the official time zone of India upon its independence on August 15th, 1947
When calculating GMT it is considered equivalent to UT1 (the modern form of mean solar time at 0° longitude), but this meaning can differ from UTC by up to 0.9 seconds.	The IST is calculated on the basis of a clock tower in Mirzapur (with coordinates 25.15° North Latitude and 82.58° East longitude).
Because of Earth’s uneven angular velocity in its elliptical orbit, GMT is rarely the exact moment the Sun crosses the Greenwich meridian	Official time signals are generated by the Time and Frequency Standards Laboratory at the National Physical Laboratory in New Delhi, for both commercial and official use. The signals are based on atomic clocks and are synchronised with the worldwide system of clocks
Since legal, political and geographical criteria, are used in the drawing of time zones, actual time zones do not precisely adhere to meridian lines. The same holds true for GMT as well because there will be discrepancies between legal and geographic GMT	The IST is insufficient to cover the geographical expanse of India. The reason is that such is the east-west distance covers about 2933 kilometres and 29 degrees of longitude resulting in the sun rising and setting almost two hours earlier on the eastern borders of India than its western borders. The proposals to divide the country into different timezones have been taken into consideration by the government of India as of late to overcome this drawback.
The term Greenwich Mean Time is used commonly in the United Kingdom and in the Commonwealth of Nations such as Australia, New Zealand and many other countries of the Eastern Hemisphere	Indian Standard Time is used observed in India and Sri Lanka but it takes references from the UTC (Universal Time Coordinate). The UTC has been developed as a successor to the Greenwich Mean Time

Aspirants can find study materials for the Geography segment of the UPSC Exams through the links given below

Difference Between GMT and IST – Download PDF Here

Become familiar with the general pattern of the UPSC Exams by visiting the UPSC Syllabus page. For more preparation materials they can refer to the links given in the table below:

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Current Affairs PDF	Universal Civil Code	PIB Summary and Analysis
Green Revolution in India	Ujala Yojana	Article 32

Frequently Asked Questions related to Time Zones

What countries are in the IST time zone?

Territories observing the time zone are primarily in southern Asia. It runs through the countries of India and Sri Lanka. Those in the time zone also refer to it as Indian or India Time (IT) and Indian Standard Time (IST).India and Sri Lanka remain on India Standard Time all year long and do not make any changes for Daylight Saving.

How many time zones are in India?

There is only one time zone across the whole of India. The time zone is calculated according to the longitude of 82.5° E. at Shankargarh Fort in Mirzapur, Uttar Pradesh, which was picked as the central meridian for India. The Assam government wanted to introduce a separate time zone across the whole state and the other northeast Indian states. A campaign was started in 2014 but it’s yet to be approved by the Central Government of India. The government is keen to retain one time zone to prevent confusion and safety issues (railway operations and flights).In many places in India, the sun rises and sets much earlier than official working hours. Sunrise is as early as 4 a.m. and sunset by 4 p.m. in northeast India, resulting in a loss of daylight hours and productivity.

Does India need 2 time zones?

A proposal for two time zones has come from India’s national timekeeper itself. Scientists at the Council of Scientific & Industrial Research’s National Physical Laboratory (CSIR-NPL), which maintains Indian Standard Time, have published a research article describing the necessity of two time zones, with the new one an hour ahead of the existing time zone. In a reply to a question in Parliament, the government said it has not taken any decision on separate time zones. A committee set up in 2002 did not recommend two time zones because of the complexities involved

Which country has most time zones?

The country with the most time zones is France (12 time zones), mostly due to its various territories around the world. The United States and Russia are tied for second place with eleven time zones each.

What is GMT?

GMT or Greenwich Mean Time is the time measured on Earth’s 0 degree longitude which passes through Old Royal Observatory near London. The 0 degree longitude runs from the North Pole to the South Pole and is referred to as the Greenwich Meridian since 1884.

Relevant Links

UPSC Mains General Studies Paper 1 Syllabus, Strategy & Structure	Difference between Advancing and Retreating Monsoon
Previous Years Geography Questions in UPSC Mains General Studies Paper- 1	Topic-Wise General Studies Paper-1 Questions in UPSC Mains

IAS General Studies Notes Links
What Is Junk Food	Zoonotic Meaning
Thermal Power Plant In India	Governance Meaning
Pradhan Mantri Gram Sadak Yojana	Essay For UPSC
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Kuznets Curve	Roshni Act

IAS General Studies Notes Links

What Is Junk Food

Zoonotic Meaning

Thermal Power Plant In India

Governance Meaning

Pradhan Mantri Gram Sadak Yojana

Essay For UPSC

Constitutional Amendments

Central Administrative Tribunal

Kuznets Curve

Roshni Act

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