Wonder what UTC Is? Understanding Time – (Knowledge Is Power Series)-[pt.6]

rgeddes (67)in #life • 8 years ago

I learned as a kid that the prime meridian ran through a pub in Greenwich, England. I knew that where I lived in North America my time zone was GMT -5. When I first went to England I knew right away to turn my watch forward 5 hours. From television I learned about the Pacific, Mountain, Central, Eastern and Newfoundland’s half time zone.

I have started seeing the denomination of time “UTC” used more and more. On Television I don’t hear much about “eastern standard time” anymore. On Canadian and American television they usually will simply say east, west or central. The internet however, Is introducing new terminology and standards to people –such as the term UTC. Much as the move to the term CE from AD to denominate time after BC – UTC and GMT are used interchangeably – so many people have not taken the time to understand what UTC actually is.

Coordinated Universal Time (UTC) is the basis for civil time today. This 24-hour time standard is kept using highly precise atomic clocks combined with the Earth's rotation. [1]

UTC is an agreed upon – coordinated - way to count time – it is not a time zone. No country uses UTC as a local time - it is simply a standardized way to count time. It is based on over 400 atomic clocks and the measurement of the earth’s rotation .

“The Greenwich Meridian (Prime Meridian or Longitude Zero degrees) marks the starting point of every time zone in the World. GMT is Greenwich Mean (or Meridian) Time is the mean (average) time that the earth takes to rotate from noon-to-noon.”[2]

Every 15 degrees longitude is one hour’s difference in time. If you multiply 25 degrees by 24 hours you end up with 360 degrees (a circle). GMT measures how many degrees you are east of (-) or west of (+) GMT or 0 degrees (also known as Zulu time).

GMT sets the time around the world. Even though it has been replaced by UTC it is still widely regarded as the correct time for every time zone. The terms are widely used interchangeably. Think of UTC as the measured unit of time and the GMT time zones as exactly that (they didn’t change).

The scientific world at least - changed from GMT (as a measurement of time) to UTC in 1967. The terms have been used interchangeably since then – especially in the Americas. Eastern Standard Time is still GMT -5 or -4 in the winter, which correlates to UTC -5 or -4. The time zones did not change - UTC is simply a more accurate “second” that we set our clocks to. It has been corrected over the years by “leap” seconds to account for the earth’s rotation which is not even.[3]

As global citizens we are now collaborating with people all over the world. The use of UTC rather than GMT is a reflection of our time – UTC is the correct time measurement – the zones are still based on GMT!