If the days seem to get shorter as you get older, you might not imagine it.
On June 29, 2022, the Earth completed a full rotation that took 1.59 milliseconds less than the average day length of 86,400 seconds, or 24 hours. Although a shortening of 1.59 milliseconds may not seem like much, it is part of a larger and more specific trend.
Indeed, on July 26, 2022, another new record was almost defined when the Earth has finished its day 1.50 milliseconds shorter than usual, as indicated by The Guardian and time tracking site Time and date. Time and Date notes that the year 2020 has recorded the highest number of short days since scientists began using atomic clocks to take daily measurements in the 1960s. Scientists 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 increased since the formation of the Earth-Moon system. That’s because over time, the force of gravity moved energy from the Earth – via the tides – to the Moon, pushing it slightly farther away from us. Meanwhile, because the two bodies are in tidal lock – meaning the Moon’s rate of rotation and revolution are equivalent so we only ever see one of its sides – physics dictates that Earth’s day must lengthen 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 much shorter.
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Although scientists know that Earth’s days are getting shorter in the near term, a definitive reason for why remains unclear, as well as the effect it might have on how we 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 said. Levine, a physicist in the time and frequency division. from the National Institute of Standards and Technology, says Discover the magazine. “You are not able to predict what will happen very far in the future.”
But Fred Watson, the Australian astronomer in general, told ABC News in Australia that if nothing is done to stop it, “you will gradually shift the seasons in relation to the calendar”.
“When you start looking at the real details, you realize the Earth is not just a solid spinning ball,” Watson said. “There’s liquid inside, there’s liquid outside, and there’s an atmosphere and all of these things move around a bit.”
Matt King of the University of Tasmania described the ABC News Australia trend as “certainly odd”.
“Clearly something has changed, and changed in ways we haven’t seen since the beginning of precise radio astronomy in the 1970s,” King said.
Could it be related to extreme weather conditions? As reported by The GuardianNASA reported that Earth’s rotation may slow stronger winds in El Niño years and may slow down the rotation of the planet. Similarly, melting ice caps displace matter on Earth and can therefore change the speed of rotation.
Although this small waste of time has little effect on our daily lives, some scientists have called for the introduction of a negative “leap second”, which subtracts 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’s entirely possible that a negative leap second could be needed if Earth’s rotation rate increases further, but it’s too early to tell if that’s likely to happen,” said physicist Peter Whibberley of the National Physics Laboratory in the UK. The Telegraph. “There are also ongoing international discussions about the future of leap seconds, and it’s also possible that the need for a negative leap second will drive the decision to end leap seconds for good.”