Spinning faster

Human endeavours like the buildingof dams are now being held responsible for the planet spinning a wee bitfaster. Benjamin Chao, a geophysicistat NASA's Goddard Space FlightCenter in Greenbelt, Maryland, US,says that the days are shortening byabout O;2millionthsofa second peryear. Chao's observations are basedon a study of artificial reservoirs likedams, and how this redistribution ofwater is affecting the earth's spin. Asmost dams are situated in theNQrthern Hemisphere, there hasbeen a net shift in the water closer tothe earth's axis and away from theequator, resulting in faster spins(DiScover, Vol17 , No 4).