Time Zones Christopher D. Smith GLG/150 July 21, 2010 The Greenwich Meridian is a north-south line representing a zero degree-reference line in longitude. The line passes through the United Kingdom and it represents the world’s prime meridian. Longitude is used to measure the distance of areas on the world east, or west. Think of it like the equator, where the equator separates the southern and northern hemispheres. The Greenwich Meridian separates the east and west hemispheres.
According to Time and date. com (2010), “GMT was first adopted as the world’s time standard at the Washington Meridian Conference in 1884. GMT is no longer the basis for civil time but is now loosely interchanged with UTC to refer to time kept on the Greenwich meridian (longitude zero)” (UTC and GMT, para. 1). The Greenwich also provides a means for world time. Starting at the Zero line, and using a 24 hour-scale, devised by how long it takes the earth to travel a full revolution to make a day.
Each time zone approximately is seen as 15 degrees wide. This equates to a one-hour difference of solar time. Time zones are not an exact straight line. Many times zone lines are changed to meet up with borders. To find civil time changes by location a person would only need to divide the longitude degrees by 15 to discover the hour difference from Greenwich Meridian. The best way to do this is to see the suns position of where he or she is at when the sun is in position of high noon.
If the longitude degrees is west subtract the difference form the world time hours. If the longitude degrees is east then add the hours. Next, when traveling around the world, following standard time an hour difference in each time zone he or she passed through arriving back which he or she started, the time devised used would of seen a full 24 hour difference in changes. The 24 hours changed would equal a full day difference form any calendar he or she would use.
To help with this issue a date line was made. The date line passes through the Pacific Ocean. When passing through this line traveling west a person would need to add a day. Traveling east through the line would respectively mean to subtract a day. References: Time and date. com. (2010). General Information on time zones. Retrieved July 21, 2010 from http://www. timeanddate. com/time/time-zones. html