This article is somewhat misleading -- the Earth's rotation is *not* slowing down by 0.002 seconds per day, despite what the article says.<br><br>Slowing 0.002 seconds per day is a second every 500 days (ca. 1-1/2 years). If the Earth's rotation was really slowing at that rate, somebody would have noticed long before the late '60s. Really: nobody in the early 1960s would have noticed that the day was *13 seconds longer* than it was during WW II? The quartz clock, accurate to thousandths of a second per day, was invented in 1928.<br><br>This means that, about 5,000 years from now, the day will be 25 hours long, and the day was only 23 hours long when the pyramids were built. 100,000 years ago, the day was only about 4 hours long. With just two hours to sleep and two hours to find food, no wonder the Neanderthals died out.<br><br>And, of course, 20,000 years before *that*, the Earth would have been a millisecond pulsar if some enterprising cave man had only thought to invent radio broadcasting.<br><br>Of course, this is all obvious nonsense. What the article actually means to say is that the Earth's rotational rate is 0.002 seconds longer than 24 hours, on average, based on the atomic-clock-defined second. It's like a clock that takes 24 hours and 1 minute to register 24 hours: it loses time by a minute per day, but the clock is not *slowing down* -- it's just *running slowly*.<br><br>The Earth's rotation <i>is</i> actually slowing down a bit, at a long-term average rate of 0.0014 seconds (1.4 milliseconds) per day every *century*. This slowing has nothing to do with leap seconds.<br><br>Terry (astrotrf)<br><br><br>