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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.
Contact Ryan Morgan at morganr@dailycamera.com or (303) 473-1333.
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