If you feel like the days are getting shorter as you age, you may not be imagining it.
On June 29, 2022, the Earth made a complete rotation that took 1.59 milliseconds less than the average day length of 86,400 seconds or 24 hours. While a shortening of 1.59 milliseconds may not sound like much, it is part of a larger and more peculiar trend.
In fact, on July 26, 2022, another new record was recorded narrowly established when Earth ended its day 1.50 milliseconds shorter than usual, as reported by The Guardian and the weather tracking website time and date. Time and Date notes that the year 2020 had the most short days since scientists began using atomic clocks to take daily measurements in the 1960s. Scientists first began noticing the trend in 2016.
While the length of an average day may vary slightly in the short term, in the long term the length of the day has been increasing since the Earth-Moon system formed. This is because, over time, the force of gravity has moved energy from the Earth, through the tides, to the Moon, moving it a little further away from us. Meanwhile, because the two bodies are in tidal lock, meaning the Moon’s rotational speed and revolution are equivalent, so we only see one side of it, physics dictates that on Earth’s day it must be lengthened if the two bodies are to remain in tidal lock. as the moon recedes. Billions of years ago, the Moon was much closer and Earth’s day length was much shorter.
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While scientists know that Earth’s days are getting shorter on a short-term scale, a definitive reason why remains unclear, along with the effect it could have on how we as humans track time.
“The rate of rotation of the Earth is a complicated matter. It has to do with the exchange of angular momentum between the Earth and the atmosphere and the effects of the ocean and the effect of the moon,” Judah Levine, physicist in the time division and frequency. of the National Institute of Standards and Technology, told Discover magazine. “You cannot predict what will happen in the distant future.”
But Fred Watson, Australia’s astronomer general, told ABC News in Australia that if nothing is done to stop it, “little by little the seasons of the calendar will go out of phase”.
“When you start to look at the real heart of the matter, you realize that the Earth is not just a solid ball that is spinning,” Watson said. “It’s got liquid on the inside, it’s got liquid on the outside, and it’s got an atmosphere and all of these things slosh around a little bit.”
Matt King of the University of Tasmania described the trend to ABC News Australia as “admittedly strange”.
“Clearly something has changed, and it has changed in a way that we haven’t seen since the beginning of precise radio astronomy in the 1970s,” King said.
Could it be related to extreme weather patterns? As reported by The GuardianNASA has reported that the spin of the Earth can slow down the strongest winds in El Niño years and can slow down the spin of the planet. Similarly, the melting of the polar ice caps moves matter on Earth and thus can change the rate of spin.
While this small loss of time has little effect on our daily lives, some scientists have called for the introduction of a negative “leap second,” which would subtract one second from a day to keep the world on track for the atomic time system. , if the trend continues. Since 1972, leap seconds have been added every few years. The last one was added in 2016.
“It is very possible that a negative leap second will be needed if the Earth’s rotation rate increases further, but it is too early to say whether this is likely to happen,” said physicist Peter Whibberley of the UK’s National Physical Laboratory. . The Telegraph. “There are also international debates about the future of leap seconds, and it’s also possible that the need for a negative leap second could drive the decision to do away with leap seconds forever.”
