Friday, June 12, 2009

Time: According to Who?

If someone asks you for the official time, your response will depend to some extent on the region of the country you live in. Keeping up with the time around the world could become a time consuming task. Nevertheless when it comes to reporting time, there are two United States Agencies who are responsible for “keeping time”. These two agencies work jointly to keep up with what they regard to be the “Official United States Time”. The two agencies entrusted with this responsibility are the United States Naval Observatory, also known as USNO and the National Institute of Standards and Technology, a Department of Commerce agency whose acronym is NIST.

In a physics classroom, the precision required by both agencies to calculate and report the most accurate time, may easily become the topic of several classroom discussions. According to the website,, the accuracy of the time captured by both the USNO and the NIST is called “World Time” or “Coordinated Universal Time (UTC)”. The website also indicates that “whenever both agencies report their time, the variation in their reports should absolutely not exceed 0.000.0001 seconds.”

Pictures: Microsoft Graphics Online

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