Earth's
journey is right on time: For fifth year, planet hasn't lagged
in its trip around sun
By Ryan Morgan, [Boulder
Daily] Camera Staff Writer
December 30, 2003
The Earth won't be
having seconds this year, thank you.
And that has scientists
across the world — including those who run the atomic clock
at the National Institute for Science and Technology in Boulder
— scratching their heads.
Apparently, the Earth
isn't slowing down as it used to, and no one knows why.
Flip your calendar
back to 1972. That's the year the world began its current system
of atomic time-keeping. NIST operates one of the clocks used
to set "Coordinated Universal Time."
Scientists soon discovered
they had a small problem: The rate at which the Earth travels
through space had slowed ever so slightly, and as a result was
completing its 365-day journey around the sun one second behind
schedule.
To make the world's
official time agree with where the Earth actually sat in space,
scientists started having the atomic clocks count an extra "leap
second" on the last day of the year.
"They came close
to matching it, but they had to add a second to keep it in sync,"
said John Lowe, a NIST researcher who works in the agency's Time
and Frequency Division.
For 28 years, scientists
repeated the procedure. Then, in 1999, they discovered that the
Earth was no longer lagging behind. It didn't need a leap second. [See
Barbara Hand Clow's The
Mayan Code. --J.N.]
This is the fifth consecutive
year that the Earth hasn't lagged behind schedule.
Fred McGehan, a spokesman
for NIST, said most scientists agree that the Earth has been
very gradually slowing down for millennia. But, he said, they
don't have a good explanation for the five years it's been on
schedule.
Possible explanations
include the tides, weather and changes in the Earth's core.
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