In the midst of all the hustle and bustle of modern life, time can often seem to fly by.
But it turns out it really is, after Earth recorded its shortest day since records began in June.
The 1.59 milliseconds shaved off the usual 24-hour turn on June 29 raises the possibility that a second negative jump would have to occur to keep the clocks aligned, which would be the first time in history that the global clocks
So why is the Earth spinning faster than usual?
Scientists say climate change, seismic activity and ocean circulation could be to blame, as well as the pull of the moon and the so-called “Chandler Wobble”, a change in the Earth’s spin on its axis .
The ‘Chandler Wobble’
The ‘Chandler Wobble’ is an oscillating motion that occurs when the Earth rotates on its axis. It works in a similar way to how a shoe wobbles as it slows down.
However, in recent years, the spin has become less wobbly, which scientists think may be related to the increased speed of Earth’s rotation, resulting in shorter days.
“The Chandler wobble is a component of the motion of the Earth’s instantaneous axis of rotation, called polar motion, which changes the position of the point on the globe where the axis intersects the Earth’s surface,” said Dr. Leonid Zotov, of the Sternberg Astronomical Institute. Moscow
“The normal amplitude of the wobble is about four meters on the Earth’s surface, but from 2017 to 2020 it disappeared.”
This historic low was reached just as the length of the days began to shorten.
Acceleration: Earth recorded its shortest day since records began in June, but why is our planet spinning faster than usual? Scientists say climate change, seismic activity and ocean circulation could all be to blame
Each day on Earth contains 86,400 seconds, but the rotation is not uniform, meaning that over the course of a year, each day is a fraction of a second or so.
WHAT IS A SECOND BAST?
A leap second is an adjustment of a single second to Coordinated Universal Time (UTC).
This is designed to keep atomic clock time and solar time online.
There are differences between the incredibly accurate international atomic time (TAI) as measured by atomic clocks and the imprecise observed solar time (UT1), linked to the Earth’s rotation.
The UTC time standard, in line with Greenwich Mean Time (GMT), is widely used for global time, including astronomy.
Without the second leap, added every few years, UTC would be out of line with the Earth’s rotation rate.
Although this would not be noticeable to most people, for hundreds of years it could change the noon point and affect the Internet.
However, it’s not a popular practice, proving to hurt some Internet services, with Google “softening” time for a year to add the microsecond increase to each day.
The international standards bodies responsible for time are debating whether to abandon the practice, since even more than 100 years would only be off by about a minute.
However, there is not much explanation as to the cause of this lack of wobbling.
Matt King, a professor at the University of Tasmania who specializes in Earth observation, told the Australian Broadcasting Corporation: “It’s certainly strange.
“It’s clear that something has changed, and it’s changed in a way that we haven’t seen since the beginning of precise radio astronomy in the 1970s.”
Climate change
Global warming is also thought to be having an effect, melting ice and snow at a faster rate.
Research has suggested that as glaciers melt, as a result of rising atmospheric temperatures from burning fossil fuels, the redistribution of mass causes the Earth to move and spin faster on the its axis
That’s because it’s causing the loss of hundreds of billions of tons of ice a year to the oceans, causing the north and south poles to move eastward since the mid-1990s.
Previously, only natural factors such as ocean currents and the convection of hot rocks in the Earth’s interior contributed to the drifting position of the poles.
But since 1980, the position of the poles has moved about 4 m (13 ft) apart.
The Earth’s spin axis, an imaginary line that runs through the north and south poles, is always in motion, due to processes that scientists do not fully understand.
But the way water is distributed on Earth’s surface is a factor that causes the axis, and thus the poles, to shift.
An example of this is the shrinking of the Greenland ice sheet as temperatures rose over the course of the 20th century.
In fact, about 7,500 gigatons (the weight of more than 20 million Empire State Buildings) of Greenland ice melted into the ocean during that time period.
This makes it one of the main contributors to the transfer of mass to the oceans, causing a rise in sea level and, consequently, a drift in the Earth’s axis of rotation.
While ice is melting elsewhere (like Antarctica), Greenland’s location makes it a bigger contributor to polar motion, as NASA’s Eric Ivins explains.
“There’s a geometric effect that if you have a mass that’s 45 degrees from the north pole, which is Greenland, or the south pole (like the Patagonian glaciers), it’s going to have a bigger impact on the axis shift of Earth’s rotation than a mass. which is near the Pole,” he said.
But if a change in the distribution of the water mass and rising sea levels can cause the Earth’s rotation to speed up, what can have the opposite effect?
NASA says stronger winds during El Niño years can slow the planet’s spin, lengthening the day by a fraction of a millisecond.
However, the impact of climate change on the rotation of the Earth is still considered to be relatively small among the scientific community.
Seismic activity
Earthquakes and other seismic activity can also have an impact on the rate of rotation of our planet.
This is because they can also move mass towards the center of the Earth, like a person swinging their arms inward, thereby shifting their weight once more.
For example, the 2004 earthquake that triggered a tsunami in the Indian Ocean displaced enough rock to shorten the length of the day by nearly three microseconds.
The large earthquakes in Chile in 2010 and Japan in 2011 also increased the Earth’s spin and thus shortened the length of the day.
Ocean circulation
Ocean circulation and pressure on the sea floor also pull on the Earth’s axis.
In November 2009, events in the Southern Ocean caused the Earth to spin slightly faster, shortening half the days of the month by 0.1 milliseconds each.
It turned out that the powerful ocean current that surrounds the continent, the Antarctic Circumpolar Current, was to blame.
About 7,500 gigatons of Greenland ice (pictured) melted into the ocean during the 20th century. This makes it one of the main contributors to the transfer of mass to the oceans, causing a rise in sea level and, consequently, a drift in the Earth’s axis of rotation.
FOUR LAYERS OF PLANET EARTH
Crust: At a depth of up to 70 km, this is the outermost layer of the Earth, covering the ocean and land areas.
Mantle: Going down to 2,890 km with the lower mantle, this is the thickest layer on the planet and is made up of silicate rocks richer in iron and magnesium than the upper crust.
Outer core: From a depth of 2,890 to 5,150 km, this region is made of liquid iron and nickel with lighter trace elements.
Inner core: Descending to a depth of 6,370 km in the very center of planet Earth, this region is thought to be made of solid iron and nickel. But this new study suggests that it contains hard iron and cake.
Experts at NASA’s Jet Propulsion Laboratory (JPL) in California and the Institute of Earth Physics in Paris, France noticed that it slowed down sharply on November 8, 2009, only to speed up two weeks later.
Accurate day length data then revealed that the changes immediately caused the Earth to spin faster, shortening each day by 0.1 milliseconds, before day length returned to normal on 20 November of that year in line with the current one.
Mystery at the core of the Earth
Some experts believe the explanation lies within the Earth itself, with something perhaps happening in the planet’s core and mantle.
“We’re not sure because the Earth is a very complex system, but I think it’s causing the Chandler decay and the day length to decrease synchronously,” Zotov said.
“No one expected the Earth to speed up.”
The speed of rotation of our planet on its axis has varied throughout history.
1.4 billion years ago, a day would pass in less than 19 hours, compared to 24 today.
So, on average, Earth’s days are getting longer rather than shorter, by about 74,000 of a second each year.
But today the planet spins faster than half a century ago.
Sometimes the rotation speed varies slightly, affecting the global timekeeper, the atomic clock, which requires adding leap seconds. Or, in the latter case, a second negative jump should occur.
Since the 1970s, a total of 27 leap seconds have been required to keep atomic time accurate.
Some experts believe the explanation lies within the Earth itself, with something perhaps happening in the planet’s core and mantle (stock image)
The last was on New Year’s Eve 2016, when clocks stopped for a second to allow Earth to catch up.
But since 2020, this phenomenon has been reversed; the previous fastest day, July 19 of that year, was 1.47 milliseconds shorter than 24 hours.
Humans cannot detect the change, but it could affect satellites and navigation systems.
Each day on Earth consists of 86,400 seconds, but the rotation is not uniform, meaning that over the course of a year, each day is a fraction of a second or so.
The atomic clock is extremely precise and measures time by the movement of electrons in atoms that have cooled to absolute zero.
The International Earth Rotation Service in Paris is responsible for keeping track of how fast the Earth is spinning, and it does so by sending laser beams to satellites…