The Hindu calendar
and
the English calendar
compared:
Many times people are found sceptical about the usage and utility of the Hindu calendar considering the wide usage and dependability upon the western calendar. The advent of British raj over the Indian subcontinent brought a doom to the respectability and reverence of the Indian culture and the related artefacts. With Indians consistently struggling for the independence of the land, they forgot the independence of mind that had so been shackled with the western school of thought for over a century. One of the many victims of this servitude is the Hindu calendar which has been completely overshadowed by the modern day calendar since the Indians are fervently trying to keep pace with the forces of globalisation which has given a common language to the whole wide world for the purpose if communicating.
But Indians have begun to depend on the Hindu calendar and they use the English calendar for their day-to-day activities. They attempt to align Indian festivals along with the dates given in the English calendar.
There exists a fundamental difference between the two calendars. In the English calendar the day changes at midnight whereas the day as per the Hindu calendar changes at sunrise. In the case of dates, the English dates change at midnight whereas the change of Hindu dates i.e. the tithis depends on interplanetary movement.
The standard rule to monitor festivals is every time a tithi exists at the time of sunrise. But this rule changes for some of the festivals according to Indian Astrology like Janmashtami, Ganesh Chaturthi, Karwa Chauth,
Mahashivratri, etc. Since there are difference in the respective sunrise times, sunset times, moonrise times and the tithi timings at different places at the globe, one may argue that there is a need for having separate Hindu Astrology calendars for different places. To avoid the confusion which different Hindu calendars may bring, the Indians in the western hemisphere instead follow the calendar used in India. Muhurtha is a totally different thing altogether. It needs the blend of tithi, vaar i.e. the day, nakshatra, lagna etc.
Now if the calendar makers present in India try to consider all the places in the face of the earth, they will have to create the calendar for every single place on earth. This will definitely raise the costs by leaps and bounds. So for the sake of customers as well as the manufacturers the Hindu calendar is made according to the IST.