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To: T L Comiskey who wrote (34027)	1/2/2004 5:36:44 AM
From: lurqer	Read Replies (2) \| Respond to of 89467

As you've gotten older, do the years seem shorter? Faster World Whirls Into 2004 The world's timekeepers, who track time using an atomic clock and the rotation of the Earth, say our planet is speeding up. Because of the faster rotation, a leap second will not be added to Coordinated Universal Time (UTC) on Dec. 31, making 2003 the fifth consecutive year without such an adjustment. Tom O'Brian, a physicist and chief of the National Institute of Standards and Technology's Time and Frequency Division, told Discovery News that the five leap-less years suggest the rotation of the Earth has exhibited an increased rate since 1999. "What has actually happened is that the rate of the rotation of the Earth has stopped slowing down," said O'Brian. He explained that since the beginning of the planet's history, Earth's rotation has been slowing down at a rate of approximately 1.5 milliseconds per century. "Evidence from 4 to 5 million years ago shows that a day was 20 hours long," said O'Brian, who explained that coral growth rings and documentation of lunar and solar eclipses allow researchers to determine both daily and annual time in the past. Both eclipses and some coral growths occur at such regular rates that they can be measured and compared with current data. Because Earth's rotation has a tendency to slow, timekeepers decided to implement leap seconds in 1972 to make UTC agree with astronomical time to within .9 second. Since 1972, 22 leap seconds have been added. Adjustments, when needed, always are made midyear and at year's end. O'Brian speculates that the apparent trend of Earth's speedier rotation could be due to climate change. "We observe effects on rotation from season to season, and Earth does speed up slightly during warmer months," he told Discovery News. "Most of our land mass is in the Northern hemisphere, and as some water evaporates and falls as snow, it is as though Earth is an ice skater holding her hands up as she completes a spin, which can increase the rate of rotation. Friction that happens when the Earth rubs against tides, and molten rock magma movements within the center of our planet also may affect rotation speeds, according to O'Brian. Australian timekeepers Peter Fisk of the Commonwealth Scientific and Industrial Research Organization and Richard Brittain, secretary of Australia's National Standards Commission, agree that no leap second should be added as 2003 draws to a close. In addition to the possible reasons given by O'Brian, Brittain added that the movement of other planets could influence our rotation. "By far this is the longest period without a leap second," said O'Brian. "The change may have to do with global weather patterns, but this is speculative at this point and we will have to wait and see what happens in future." dsc.discovery.com lurqer