How IST (Indian Standard Time) works?

We all know that India is a vast country. But how much vast?

Well, India's extreme East and West covers almost 30° of longitude. So which means that there is difference of almost 2 hours in real time sunrise.

Yes, you heard it correct. Sun rises in Arunachal Pradesh almost two hours before it does in Kutch of our Gujarat.

Well, if we go by geography and real time earth rotation, then India should have 3 time zones. But on the contrary, India has only one uniform time zone. This one time zone is called as IST (Indian Standard Time).

This term IST was officially adopted by India on 1st September 1947.

First question arises:
Why doesn't India have two time zones or only one time zone?
Let me answer that question:

1) Administrative and Governance Unity:

Operating under one central clock prevents confusion in central government administration, defence, banking and all other integrated government sectors.

2) Transportation and Logistics:

A unified time simplifies complex timetables for the Indian Railways, national aviation networks, reducing the risk of transit errors or scheduling collisions.

i.e. Think how to accept that flight from Ahmedabad to Calcutta will take off at 9:30 am and land at 10:00 am in Calcutta.

Plus, on landing in Calcutta, we all will have to adjust our wrist watch time to 1 or 1½ hours.

Right, very confusing. So to avoid that there is one time zone.

3) Most important aspect:

Post Independence, one unified time zone adopting also symbolised unity, i.e. unified India – one time zone.

Well, our IST is chosen by taking 82.5° East longitude, passing near Mirzapur and Prayagraj (formerly Allahabad).

This longitude is the central point or almost half way between two extremes of East and West India.

Do you know there is one clock tower at Amjhara, Mirzapur, near Prayagraj, which states that this is the central time zone point of India.

Well, there are certain natural side effects also of the single time zone of India due to real sunlight timings, but then those things are some other day.

Till then we can say that though sun's time / solar clock timings may differ from east to west, but not only by just like position, our wrist watches also tunes “Hum Sath Sath Hain.”

Thank you.

Mr. Dhawal Shah
Teacher - Chemistry