How GMT is calculated?

Answer 1

Greenwich Mean Time. Greenwich, just outside London, England sits on Longitude 0. All sea traffic took it's timing from Greenwich. Sir Sanford Fleming, a Canadian, proposed in 1878 that the world adopt a common system of time measurement focused on a central point. Consequently, there are 24 time zones around the world, 12 in advance and 12 after GMT. They were set as 1 hour intervals per 15 degrees of longitude. On large continents that rigidity is unfeasible, some states would be divided into 2 time zones. So for ease of management, congress sets the demarcation lines of the 5 US time zones. The 3 Australian time zones are similarly managed. Because the lines of longitude converge at the poles, the 24 time zones become as one. Therefore UTC (Coordinated Universal Time) is used there.

Answer 2

Greenwich Mean Time (GMT) is calculated based on the Earth's rotation around its axis with respect to the prime meridian, which runs through the Greenwich Observatory in London, UK. GMT is determined by measuring the time it takes for the Earth to complete one full rotation (24 hours) starting from noon at Greenwich, with each hour representing 15 degrees of longitude. This standard was established in the 19th century for global timekeeping.

Answer 3

The Royal Observatory in Greenwich- the Greenwich Line or Prime Meridian longitude 0 degrees 0' 0"