[D66] The Earth has been spinning faster lately

[R.O.]

  The Earth has been spinning faster lately

By
Bob Yirka
phys.org
2 min
View Original 
<https://getpocket.com/redirect?url=https%3A%2F%2Fphys.org%2Fnews%2F2021-01-earth-faster.html>

Credit: CC0 Public Domain

Scientists around the world have noted that the Earth has been spinning 
on its axis faster lately—the fastest ever recorded. Several scientists 
have spoken 
<https://www.telegraph.co.uk/news/2021/01/04/earth-spinning-faster-now-time-past-half-century/> 
to the press about the unusual phenomenon, with some pointing out that 
this past year saw some of the shortest days ever recorded.

For most of the history of mankind, time has been marked by the 24-hour 
day/night cycle (with some alterations made for convenience as the 
seasons change). The cycle is governed by the speed at which the planet 
spins on its axis. Because of that, the length of a day has become the 
standard by which time is marked—each day lasts approximately 86,400 
seconds. The day/night cycle is remarkably consistent despite the fact 
that it actually varies slightly on a regular basis.

Several decades ago, the development of atomic clocks began allowing 
scientists to record the passage of time in incredibly small increments, 
in turn, allowing for measuring the length of a given day down to the 
millisecond. And that has led to the discovery that the spin of the 
planet is actually far more variable than once thought. Since such 
measurements began, scientists have also found that the Earth was 
slowing its spin very gradually (compensated by the insertion of a leap 
second now and then)—until this past year, when it began spinning 
faster—so much so that some in the field have begun to wonder if a 
negative leap negative second might be needed this year, an 
unprecedented suggestion. Scientists also noted that this past summer, 
on July 19, the shortest day ever was recorded—it was 1.4602 
milliseconds shorter than the standard.

Planetary scientists are not concerned about the new finding; they have 
learned that there are many factors that have an impact on planetary 
spin—including the moon's pull, snowfall levels and mountain erosion. 
They also have begun wondering if global warming 
<https://phys.org/tags/global+warming/> might push the Earth to spin 
faster as the snow caps and high-altitude snows begin disappearing. 
Computer scientists, on the other hand, are somewhat concerned about the 
shifting spin speed—so much of modern technology 
<https://phys.org/tags/modern+technology/> is based on what they 
describe as "true time." Adding a negative leap second could lead to 
problems, so some have suggested shifting the world's clocks from solar 
time to atomic time <https://phys.org/tags/time/>.


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