Earth Is spinning faster now than it was 50 years ago

Earth Is spinning faster now than it was 50 years ago

Ever feel like there’s just not enough time in the day? It appears like you may be onto something. The Earth is rotating faster than it has in the last half-century, resulting in somewhat shorter days than we’re used to. And while it’s an infinitesimally small difference, it’s become a big headache for physicists, computer programmers, and even stockbrokers.

Why Earth rotates

Around 4.5 billion years ago, a dense cloud of interstellar dust and gas collapsed in on itself and began to spin. Because of angular momentum — essentially, “the tendency of the rotating body to continue rotating until something actively tries to stop it,” explains Peter Whibberley, a senior research scientist at the UK’s National Physical Laboratory — there are remains of this original movement in our planet’s current rotation.

Our earth has been spinning for billions of years due to angular momentum, and we experience night and day. But it hasn’t always spun at the same rate.

Earth made roughly 420 rotations in the time it took to orbit the Sun hundreds of millions of years ago; we can discover evidence of how each year was jam-packed with additional days by examining growth lines on fossil corals. Although days have gradually grown longer over time (due in part to how the moon pulls at Earth’s oceans, which slows us down a bit), under humanity’s watch, we’ve remained consistent at around 24 hours for a full rotation — which equates to about 365 rotations per trip ’round the Sun.

However, as scientists have improved at measuring Earth’s rotation and keeping track of time, they’ve discovered that there are little changes in how long it takes to complete a full rotation.

A new way to track time

Scientists invented atomic clocks in the 1950s that kept time by measuring how electrons in cesium atoms fell from a high-energy, excited state to their normal state. Because the periods of atomic clocks are formed by this unchanging atomic behavior, they are not affected by external variables such as temperature shifts in the same way that traditional clocks are.

Over time, however, scientists discovered an issue: the unimpeachably accurate atomic clocks were drifting slightly from the time that the rest of the world observed.

“As time goes on, there is a gradual divergence between the time of atomic clocks and the time measured by astronomy, that is, by the position of Earth or the moon and stars,” says Judah Levine, a physicist in the time and frequency division of the National Institute of Standards and Technology. Basically, a year as recorded by atomic clocks was a bit faster than that same year calculated from Earth’s movement. “In order to keep that divergence from getting too big, in 1972, the decision was made to periodically add leap seconds to atomic clocks,” Levine says.

Leap seconds act similarly to the leap days that we tack to the end of February every four years to make up for the fact that Earth orbits the Sun in 365.25 days. However, unlike leap years, which occur every four years, leap seconds are unpredictable.

The International Earth Rotation and Reference Systems Service measures the speed of the planet’s rotation by sending laser beams to satellites to measure their movement, among other methods. When the time plotted by Earth’s movement reaches one second behind time measured by atomic clocks, scientists throughout the world coordinate to stop atomic clocks for exactly one second, at 11:59:59 pm on June 30 or December 31, to allow astronomical clocks to catch up. Voila — a leap second.

Unexpected change

Scientists have added leap seconds every few years since the first one was added in 1972. They are added in an erratic way because the Earth’s rotation is erratic, with intermittent periods of speeding up and slowing down that disrupt the planet’s millions of years-long gradual deceleration.

“The rotation rate of Earth is a complicated business. It has to do with exchange of angular momentum between Earth and the atmosphere and the effects of the ocean and the effect of the moon,” Levine says. “You’re not able to predict what’s going to happen very far in the future.”

However, in the last decade or so, Earth’s rotating slowdown has…well, slowed. Since 2016, there hasn’t been a leap second added, and our world is already spinning faster than it has in half a century. Scientists aren’t sure why.

“This lack of the need for leap seconds was not predicted,” Levine says. “The assumption was, in fact, that Earth would continue to slow down and leap seconds would continue to be needed. And so this effect, this result, is very surprising.”

The trouble with leap seconds

Scientists may have to take action depending on how much the Earth’s rotation speeds up and how long that trend continues. “There is this concern at the moment that if Earth’s rotation rate increases further that we might need to have what’s called a negative leap second,” Whibberley says. “In other words, instead of inserting an extra second to allow Earth to catch up, we have to take out a second from the atomic timescale to bring it back into state with Earth.”

A negative leap second, on the other hand, would provide scientists with an entirely new set of issues. “There’s never been a negative leap second before and the concern is that software that would have to handle that has never been tested operationally before,” Whibberley adds.

Whether a regular leap second or a negative leap second is required, these minute alterations can cause major problems for industries ranging from telecommunications to navigation systems. Because leap seconds mess with time in ways that computers aren’t designed to handle.

“The primary backbone of the internet is that time is continuous,” Levine says. Things fall apart when there isn’t a steady, continuous flow of information. Repeating a second or skipping over it trips up the whole system and can cause gaps in what’s supposed to be a steady stream of data. Leap seconds also pose a problem for the financial industry, which requires each transaction to have its own unique time stamp – a potential problem when that 23:59:59 second repeats itself.

Some companies, such as Google smear, have found their own solutions to leap seconds. On a leap second day, instead of stopping the clock to allow Earth to catch up with atomic time, Google makes each second slightly longer. “That’s a way of doing it,” Levine says, “but that doesn’t agree with the international standard for how time is defined.”

Time as a tool

In the grand scale of things, however, we’re only talking about a fraction of a second every couple of years. You’ve lived through plenty of leap seconds and probably weren’t even aware of them. And if we consider time to be a tool for measuring what we perceive in the world around us, such as the transition from one day to the next, there’s an argument to be made for following the time established by Earth’s movement rather than the electrons in an atomic clock – no matter how exact they may be.

Levine says he thinks that leap seconds might not be worth the trouble they cause: “My private opinion is that the cure is worse than the disease.” If we stopped adjusting our clocks to account for leap seconds, it could take a century to get even a minute off from the “true” time recorded by atomic clocks.

Still, he admits that, while time is only a construct, a clearly human attempt to make sense of our experiences in a large, weird cosmos, “it’s still true that at 12 o’clock noon, the Sun is overhead. So, even if you don’t think about it often, you have a connection to astronomical time.” Leap seconds are just a tiny, nearly invisible way of keeping that link alive.

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Freeda Miller
Freeda Miller
5 months ago

Earth is not spinning it’s stationarif it were spinning we would feel the torque. Think people, the torque would send things flying away ! Be a critical thinker. I wonder why they lie about this!!

Max Burkett
Max Burkett
Reply to  Freeda Miller
5 months ago

The upward force due to Earth’s spin is .026 Newtons at the equator (zero at the poles). The downward force due to gravity is about 9.8066 everywhere, 9.8066/.026 is about 377. I’m guessing that I’m in the liar category because I opine that the gravitational force keeps all solids pretty much glued to Planet Earth.

James T
James T
Reply to  Freeda Miller
5 months ago

How can flat Earth spin?

Reply to  James T
5 months ago

@James: You’ve read this book, I can tell.

Humor - The Big Book of Online Trolling - 20131015-13220216-trolling.jpg
5 months ago


5 months ago

Aren’t the wind farms slowing it down?

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