The Earth is spinning too fast – the consequences for timing could be unprecedented

Our house the planet is in a hurry. On June 29, 2022, Earth completed the shortest day since scientists started keeping records in the 1960s, performing a full rotation 1.59 milliseconds faster than usual.

earthly haste is a trend. In 2020, the planet recorded the 28 shortest days recorded, and it has continued to spin rapidly through 2021 and 2022. Before scientists could even verify that record-breaking day of June 29, our world nearly outdid itself: it soared until July 26, 2022, 1.50 millisecond before the scheduled date.

We’ll likely see more record-breaking days as Earth continues to accelerate, says Judah Levine, a professor at the University of Colorado at Boulder and a longtime expert at the National Institute of Standards and Technology (NIST). The fact that Earth’s days are getting shorter is not a cause for concern, he says, because the actual time difference amounts to fractions of a second over the course of a year. But what’s odd is that while scientists know that changes to the Earth’s inner and outer layers, oceans, tides and climate can affect how fast it spins, they don’t. what motivates the current rush.

Nobody is perfect – not even our planet. On average, the Earth rotates on its axis every 24 hours, or every 86,400 seconds. But for a variety of reasons, from the planet’s imperfect shape to its complicated interior, each day isn’t exactly the same length as the day before.

Also, a day of exactly 24 hours is only a standard we expect at present. The Earth’s rotation slows down in the long term thanks to the pull of the Moon on our world. A few hundred million years ago, for example, an Earth day was only 10 p.m.. In the millennia to come, an Earth Day will last much longer.

So what about the shorter days at the end, which go against the long-term trend? One hypothesis that has been made so far relates to the “Chandler wobbles.” Discovered in the 1800s, the phenomenon explains how the Earth, not quite perfectly round, oscillates very slightly, like a spinning top when it slows down. Leonid Zotov says timeanddate.com that the oscillation mysteriously disappeared between 2017 and 2020, which could have helped Earth end the day a little faster.

Another idea is that climate change could affect the rotational speed of the planet. When glaciers melt into the ocean, the shape of the Earth changes slightly, becoming flatter at the poles and bulging at the equator. But Levine says this effect can’t explain why the planet would suddenly spin faster because melting glaciers should have the opposite effect: the planet moment of inertia would increase, which would slow us down.

For Levine, the likely culprit is more mundane.

“One possibility is the exchange of momentum between the Earth and the atmosphere,” he says. “The sum of these two is a constant, which means, for example, if the atmosphere is slowing down, then the Earth is speeding up. Or conversely, if the atmosphere is speeding up, then the Earth is slowing down.

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The same thing can happen deep within our world: it is possible that the deep core and the mantle – the large layer that exists between the core and the surface – are moving at slightly different speeds. There could be an exchange of angular momentum between Earth’s deep core and the mantle, he speculates.

“These two effects … can either pump in velocity from the Earth’s surface or remove velocity from the Earth’s surface,” Levine explains. But the dynamics of the Earth’s atmosphere and interior are so complex that it’s impossible, at least for now, to point to any one of these factors as the sure cause of the planet’s frenetic pace.

Nature does not always adhere to the rigidity of a clock or calendar, and planetary timepieces are used to making some adjustments. A leap year, for example, exists because we need an extra day every four years to keep the 365-day calendar in sync with the Earth’s revolution around the Sun. Because the day lengthens over time as the Earth’s rotational speed slows, timekeepers activate from time to time to keep human time in sync with the solar system.

With the acceleration of the Earth, we are faced with an unprecedented possibility: to add a “negative leap second”. In other words, says Levine, if the planet continues to spin too fast, then by the end of the decade, master watchmakers may have to cut out a full second. For example, they can jump clocks from 11:59:58 PM on December 31, 2029 to 00:00:00 AM on January 1, 2030.

“If you had asked me about the negative [leap second] five years ago,” says Levine, “I would have said, ‘Never.’ But over the past two years, the Earth has definitely accelerated. And now, if this acceleration were to continue – and there is a big if there – then we might need a second negative lead in about seven years, maybe eight.

This has never been done before. Some scientists wonder if this could introduce troubling hiccups into computer systems. Given how our world continues to surprise us, however, Levine isn’t yet convinced the time will come.

“You have to remember that this requires a six-year extrapolation – and we have already been burned by the extrapolations. So I wouldn’t bet the farm.

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