There are 15 degrees in each time zone. Before 1878, it was really hard to keep track of time as people base their time based on solar motions – if the sun has reached its maximum or its minimum altitude over the horizon. It wasn’t until Sir Sanford Fleming suggested a worldwide system of time zones in 1878 wherein Earth would be divided in 24 time zones since the Earth rotates once every twenty-four (24) hours with each time zones having 15 degrees longitude. In 1884, the International Prime Meridian Conference held in Washington D.C. adopted this method and determined the Royal Observatory located in Greenwich to be the location of the Prime Meridian – this in turn became the standard time called Greenwich Mean Time.
