Question

Why is IST ahead of GMT?

Answer 1

The Earth has been divided into longitudes so that the time of any place can be calculated. Three hundred and sixty degrees are divided into twenty-four hours of time period. So, one degree accounts for 4 minutes. The standard time of India is calculated at 82${\frac{1}{2}}^{\mathrm{o}}$ east of Greenwich. It means that the meridian of IST is located in the Eastern Hemisphere. Sunrise is accordingly calculated in this hemisphere. Hence, the meridians in this hemisphere are ahead of GMT. On multiplying the meridian 82${\frac{1}{2}}^{\mathrm{o}}$ with 4 minutes, we get 5 hours and 30 minutes. This way IST is ahead of GMT.