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Desert Diary


Arguing over seconds doesn't seem like it should be important, but depending on who wins, your descendants might see our desert sun rising when the clock says midnight. The difficulty is that two commonly used ways of keeping time are incompatible with each other. Atomic clocks are widely used in science and are required by the global positioning system as a measure of absolute time. Such clocks deviate from true time at rates measured by much less than a second over a million years.

The other way of keeping time is called universal time and is based on the rotation of the earth. The difficulty is that the earth's turning is slowing down because of interaction with the moon. Since 1972, 32 "extra" seconds have had to be added to universal time to keep time and revolution in sync.

With the world's primary navigation system on atomic time while airlines and air-traffic controllers are on universal time, eventual disaster is feared. If universal time wins, the sun rises at its normal time, but flying becomes much more risky.
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Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.



Brumfiel, G. 2003. Astronomers leap to defence of extra seconds in time debate. Nature 423:671.

Web Resources

Extra Second