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Chilean earthquake makes the day shorter

2 Mar 2010, 16:30 UTC
Chilean earthquake makes the day shorter
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The devastating earthquake which struck Chile on February 27th may well have had an effect of the rotation of the Earth itself according to a NASA scientist. Richard Gross of the Jet Propulsion Laboratory has used computer models to calculate that our day is now about 1.26 microseconds shorter than it was on February 26th.
A small amount and yet it serves as a reminder that whilst we have exactly twenty four hours in our standard day, this never quite matches the actual rotation period of the Earth. Back in 1999 Gross published a paper in Physics of the Earth and Planetary Interiors in which he modeled the spin of the Earth from 1832 to 1997. The shortest day on record was apparently August 2nd 2004 whereas the longest day was sometime during 1912, the year the Titanic sank.
“The annual changes in the length of the day are caused mostly by the atmosphere – changes in the strength and direction of the winds, especially the jet stream. The Sun warms the equator more than the poles. That temperature difference is largely responsible for the jet stream. Seasonal changes in that temperature difference cause changes in the winds and, hence, ...

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