As the Length of Days on Earth Changes, Scientists Search for Answers
Micah Hanks·August 11, 2022
The Intelligence Brief
Welcome to this week’s installment of The Intelligence Brief… with recent data showing surprising changes in the length of days on our planet, this week, we’ll be looking at 1) how scientists were able to measure the shortest day on Earth since the creation of atomic clocks, 2) what existing data has to say about the frequency of shorter days in the future, 3) the long history of changes in Earth’s rotation, and 4) how atomic clocks are revealing new data about this longstanding planetary phenomenon.
Not the First Time
Two years ago, on July 19, 2020, a similar record-breaking length detection of 1.47 milliseconds shorter than average was also detected.
The pair of dates mark what some scientists interpret as the reversal of a longstanding trend observed since at least 1820 when scientists first began to note the apparent slowing of Earth’s rotation.
According to a recent CNN report, “Researchers do not have a definitive answer on how or why Earth is turning slightly faster,” noting the opinion of Dennis McCarthy, the former director of time at the US Naval Observatory, who explained that the phenomenon “may be due to glacial isostatic adjustment, or the movement of land due to melting glaciers.”
While that might not seem like all that much, if we go far enough back in time, perhaps to the tune of several billions of years ago, the length of a day on our planet would have been close to four hours shorter than our current 24-hour days.
However, as King and Watson note, the gradual slowing of Earth’s rotation began to be lessened somewhat in the final few thousand years of the Pleistocene, the previous geological epoch where ice accumulation around Earth’s polar regions was much greater (hence it being referred to as an Ice Age). As global temperatures began to warm, the melting of ice around the poles has likely reduced surface pressure on our planet, resulting in isostatic adjustment, in other words, gradual changes in the positioning of land as pressure from the glaciers lessened.
“Just as a ballet dancer spins faster as they bring their arms toward their body – the axis around which they spin – our planet’s spin rate increases when this mass of mantle moves closer to Earth’s axis,” King and Watson explain. “This process has been shortening each day by about 0.6 milliseconds each century.”
https://thedebrief.org/as-the-length-of-days-on-earth-changes-scientists-search-for-answers/
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Atomic clocks, combined with precise astronomical measurements, have revealed that the length of a day is suddenly getting longer, and scientists don't know why.
This has critical impacts not just on our timekeeping, but also things like GPS and other technologies that govern our modern life.
Over the past few decades, Earth's rotation around its axis - which determines how long a day is - has been speeding up. This trend has been making our days shorter; in fact, in June 202 ..
Read more at:
https://economictimes.indiatimes.com/magazines/panache/the-ever-changing-planet-why-is-earth-suddenly-slowing-down/articleshow/93449558.cms?utm_source=contentofinterest&utm_medium=text&utm_campaign=cppst
While the clocks in our phones indicate there are exactly 24 hours in a day, the actual time it takes for Earth to complete a single rotation varies ever so slightly. These changes occur over periods of millions of years to almost instantly - even earthquakes and storm events can play a role.
It turns out a day is very rarely exactly the magic number of 86,400 seconds.
Read more at:
https://economictimes.indiatimes.com/magazines/panache/the-ever-changing-planet-why-is-earth-suddenly-slowing-down/articleshow/93449558.cms?utm_source=contentofinterest&utm_medium=text&utm_campaign=cppst
https://economictimes.indiatimes.com/magazines/panache/the-ever-changing-planet-why-is-earth-suddenly-slowing-down/articleshow/93449558.cms 
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As the Length of Days on Earth Changes, Scientists Search for ...
... geological epoch where ice accumulation around Earth's polar regions was
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The Ever-Changing Planet
Over millions of years, Earth's rotation has been slowing down due to friction effects associated with the tides driven by the Moon. That process adds about about 2.3 milliseconds to the length of each day every century. A few billion years ago an Earth day was only about 19 hours.
For the past 20,000 years, another process has been working in the opposite direction, speeding up Earth's rotation. When the last ice age ended, melting polar i ..
Read more at:
https://economictimes.indiatimes.com/magazines/panache/the-ever-changing-planet-why-is-earth-suddenly-slowing-down/articleshow/93449558.cms?utm_source=contentofinterest&utm_medium=text&utm_campaign=cppst
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