Originally, all time on Earth was some local apparent solar time, the time on a sundial, so every city had its own time. When well-regulated mechanical clocks became widespread in the early 19th century, each city began to use some local mean solar time. The first time zone was created in 1847 by railroads on the island of Great Britain using GMT. Sandford Fleming of Canada proposed worldwide hourly time zones in 1879. By about 1900, almost all time on Earth was in the form of standard time zones, only some of which used an hourly offset from GMT. Many applied the time at a local astronomical observatory to an entire country, without any reference to GMT. It took many decades before all time on Earth was in the form of time zones referred to some "standard offset" from GMT/UTC. Nepal was the last country to adopt a standard offset, shifting slightly to UTC+5:45 in 1986. Daylight saving time or Summer Time, an advance of one hour, is mandated by many countries between spring and autumn. Computer operating systems use either UTC or a local time zone to time stamp events.
Indian Standard Time is the time observed throughout India and Sri Lanka, with a time offset of UTC+05:30. India does not observe daylight saving time (or other seasonal adjustments, although DST was used briefly during the Sino-Indian War of 1962 and the Indo-Pakistani Wars of 1965 and 1971.After independence in 1947, the Indian government established IST as the official time for the whole country, although Kolkata and Mumbai retained their own local time for a few more years. Indian Standard Time is calculated on the basis of 82.5 E longitude, which is just west of the town of Mirzapur, near Allahabad in the state of Uttar Pradesh.
The country's east-west distance of more than 2,000 km (1,200 mi) covers over 28 degrees of longitude, resulting in the sun rising and setting almost two hours earlier on India's eastern border than in the Rann of Kutch in the far west. Inhabitants of the north-eastern states have to advance their clocks with the early sunrise and avoid the extra consumption of energy after daylight hours. In the late 1980s, a team of researchers proposed separating the country into two or three time zones to conserve energy. The binary system that they suggested involved a return to British-era time zones; the recommendations were not adopted.
In 2001, the government established a four-member committee under the Ministry of Science and Technology to examine the need for multiple time zones and daylight saving. The findings of the committee, which were presented to Parliament in 2004 by the Minister for Science and Technology, Kapil Sibal, did not recommend changes to the unified system, stating that "the prime meridian was chosen with reference to a central station, and that the expanse of the Indian State was not large."
Though the government has consistently refused to split the country into multiple time zones, provisions in labour laws such as the Plantations Labour Act, 1951 do allow the Central and State governments to define and set the local time for a particular industrial area.
Indian Standard Time is the time observed throughout India and Sri Lanka, with a time offset of UTC+05:30. India does not observe daylight saving time (or other seasonal adjustments, although DST was used briefly during the Sino-Indian War of 1962 and the Indo-Pakistani Wars of 1965 and 1971.After independence in 1947, the Indian government established IST as the official time for the whole country, although Kolkata and Mumbai retained their own local time for a few more years. Indian Standard Time is calculated on the basis of 82.5 E longitude, which is just west of the town of Mirzapur, near Allahabad in the state of Uttar Pradesh.
The country's east-west distance of more than 2,000 km (1,200 mi) covers over 28 degrees of longitude, resulting in the sun rising and setting almost two hours earlier on India's eastern border than in the Rann of Kutch in the far west. Inhabitants of the north-eastern states have to advance their clocks with the early sunrise and avoid the extra consumption of energy after daylight hours. In the late 1980s, a team of researchers proposed separating the country into two or three time zones to conserve energy. The binary system that they suggested involved a return to British-era time zones; the recommendations were not adopted.
In 2001, the government established a four-member committee under the Ministry of Science and Technology to examine the need for multiple time zones and daylight saving. The findings of the committee, which were presented to Parliament in 2004 by the Minister for Science and Technology, Kapil Sibal, did not recommend changes to the unified system, stating that "the prime meridian was chosen with reference to a central station, and that the expanse of the Indian State was not large."
Though the government has consistently refused to split the country into multiple time zones, provisions in labour laws such as the Plantations Labour Act, 1951 do allow the Central and State governments to define and set the local time for a particular industrial area.
