?But we don't need to adjust our clocks - The spin of the Earth
is slowing down. Not by much; only about 0.002 seconds a day (it
varies), relative to our modern definition of the second. The
varying rotation of the Earth is due to the cumulative effect of
friction from the ocean's tides, the moon?s orbital momentum,
snow (and the lack thereof) at the polar ice caps, the 23-degree
tilt of the earth, the atmosphere, solar wind, space dust and
magnetic storms. Because of all these factors, the earth does
not rotate EXACTLY one time every 24 hours (or 86,400 seconds).
This fact went unnoticed until the highly accurate atomic clocks
developed by the National Institute of Standards and Technology
(NIST) and others around the world arrived on the timekeeping
scene in the late 1960s. Thanks to precise measurements of the
position of the earth relative to the stars made possible by the
atomic clock, the earth's rotation was found to be gradually
slowing down. But the miniscule slowing of the rotation is not
the primar