How bizarre.

For two weeks in November 2009, ocean currents flowing around Antarctica changed noticeably enough to temporarily speed up the planet's spin by about one ten-thousandth of a second. Scientists precisely monitor the length of Earth's day through space geodetic techniques, such as counting how long it takes laser light to travel from Earth to a mirror on the moon and back again. Big changes in how mass is distributed across the planet--such as changes in the atmosphere, or a monster earthquake--can alter the pace of rotation. The 2009 shift in Antarctica marks the first time such a shift has been traced to a short-term pattern in the oceans, scientists from NASA's Jet Propulsion Laboratory in Pasadena, Calif., and Paris Diderot University in France report February 28 in Geophysical Research Letters.

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