Time and Navigation

For a long time, navigation meant “finding your way around the planet.”

If you were on land you probably had landmarks and trails, and you also didn’t move very far while you were sleeping. Local sailors knew the coastlines and could navigate that way.

On the open sea, however, things were different. If you lived on one of the Pacific Islands (for example), you learned about the currents in the sea and the stars in the sky. With the stars in the sky you could figure out where you were when sailing from one island to another. There is plenty of available information on the early methods of navigation[nbnote ]http://en.wikipedia.org/wiki/History_of_navigation[/nbnote], and great strides were made by Muslims[nbnote ]http://www.ehow.com/info_8341993_ancient-muslim-navigational-instruments.html[/nbnote]. In the Middle Ages there was a great desire to improve navigation[nbnote ]http://www.columbusnavigation.com/cn.shtml[/nbnote] and there was a great push to advance the technology between 1500-1800 as we realized that if we knew what time it was we could determine our longitude. We also shifted from using the quadrant and astrolabe[nbnote ]http://en.wikipedia.org/wiki/Astrolabe[/nbnote] to the sextant[nbnote ]http://en.wikipedia.org/wiki/Sextant[/nbnote]. It was in the 1700s that John Harrison[nbnote ]http://en.wikipedia.org/wiki/John_Harrison[/nbnote] invented the Marine Chronometer, a long-sought timekeeping device to solve the problem of establishing one’s East/West position (longitude)[nbnote ]http://en.wikipedia.org/wiki/Longitude_by_chronometer[/nbnote] at sea. This is really important because if your clock is off by one second that means your longitude will be off by .29 miles (at the equator). You also have to wind your spring-driven clock at about the same time each day.  http://en.wikipedia.org/wiki/Navigation is a good place to learn more about this. Time and navigation are inextricably linked together.

Nowadays we have satellite navigation to help us know where we are. These satellites contain several very precise and accurate clocks, because time and location are completely and totally inter-related in satellite navigation.

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