Despite the record for the shortest day just set, Earth has just happened unprecedented in 50 years!

According to scientists, from precise astronomical observations, combined with atomic clocks, they found that the length of a day suddenly becomes longer. And it’s worth mentioning that scientists don’t know why either!

This has important implications for things like GPS and other precision technologies that govern our modern lives.

WHAT IS THE SPECIFIC PROBLEM?

The Earth’s rotation around its axis has accelerated over the past few decades. Since this determines the length of a day, this trend has made our days shorter. In fact, on June 29, 2022, Earth set the record for the shortest day since man used an atomic clock to measure the planet’s rotation – That day, a Wednesday, 1.59 milliseconds shorter than 86,400 seconds, or 24 hours.

However, despite this record, since 2020, that steady rate has turned to a strange deceleration . Now, the days are getting longer, and the reason is still a mystery. This change is unprecedented in the past 50 years.

Precise measurements show that Earth’s rotation has mysteriously slowed since 2020, making days longer. Photo: Scitechdaily

Although the clocks in our phones indicate that there are exactly 24 hours in a day, the actual time it takes for the Earth to complete one revolution can vary slightly. These changes sometimes occur over a period of millions of years. This indicates that a day very rarely lasts exactly the magic number 86,400 seconds.

According to scientists, the Earth’s rotation speed is not fixed and the blue planet is rotating more and more slowly, making the time of 1 day longer and longer. Estimates show that, a few billion years ago, an Earth day was only about 19 hours long; About 200 million years ago, a day on Earth was only about 23 hours long. At an average rate of every 100 years, 1 day on Earth will be longer by about 0.002 seconds, it is predicted that in the next 200 million years, 1 day on the blue planet will probably be 25 hours, VTV information .

EARTH ALWAYS CHANGES

Earth’s rotation around its axis has slowed for millions of years due to the effects of tidal-related friction driven by the Moon.

Over the past 20,000 years, another process has been working in the opposite direction, accelerating the Earth’s rotation. When the last ice age ended, the ice sheets at the poles melted, reducing surface pressure, and the Earth’s mantle began to move steadily toward the poles.

Like a ballet dancer, our planet’s rotation rate increases as this mantle moves closer to Earth’s axis. This process has been shortened every day by about 0.6 milliseconds per century.

For decades and more, the connection between the Earth’s core and the Earth’s surface also comes into play. Large earthquakes can vary the length of the day, although usually small earthquakes. For example, the 2011 Great Tōhoku earthquake in Japan, with a magnitude of 8.9, is thought to have increased the Earth’s rotation by 1.8 microseconds.

In addition to these large-scale changes, shorter-term weather and climate also have important effects on the Earth’s rotation, causing variations in both directions.

Biweekly and monthly tidal cycles move mass around the planet, causing changes in the length of the day of up to milliseconds in either direction. We can see tidal variation in day length records over a period as long as 18.6 years.

The movement of our atmosphere has a particularly powerful effect, and ocean currents also play a role. Seasonal snow cover and rainfall, or groundwater extraction, also change things further.

WHY IS EARTH SUCCESSFULLY SLOWED?

Since the 1960s, when radio telescope operators around the Earth began to invent techniques for the simultaneous observation of cosmic objects such as quasars, we have had very accurate estimates. about the Earth’s rotational speed.

Comparisons between these measurements and atomic clocks have shown that day lengths have never seemed to shorten over the past few years.

But there is a surprising revelation when we remove rotational speed fluctuations that we know are caused by tides and seasonal effects. Although Earth reached its shortest day on June 29, 2022, the long-term orbit appears to have shifted from short to long since 2020.

The reason for this change is not clear. Scientists suggest several possibilities:

On June 29, 2022, the Earth set the record for the shortest day since man used atomic clocks to measure the planet’s rotation – That day, a Wednesday, 1 shorter, 59 milliseconds versus 86,400 seconds, which is 24 hours. Photo: Internet

First, it may be due to changes in the weather system, with successive La Niña events, even though these events have occurred before. It may accelerate the melting of the ice sheets, although they are not much deviated from their steady melting rate in recent years;

Next, could it be related to the massive volcanic explosion in Tonga that pumped huge amounts of water into the atmosphere? Probably not, since that happened in January 2022.

Scientists have speculated that the mysterious recent change in the planet’s rotational speed is related to a phenomenon known as “Chandler wobble” – a small deviation in the Earth’s axis of rotation with a period of about 430 days.

Leonid Zotov, a Russian mathematics professor, believes that the Earth can rotate faster because of a periodic motion known as the “Chandler wobble”. Oscillations were first detected in the late 1880s, when American astronomer Seth Carlo Chandler (1846-1913) noticed the poles oscillating over a 14-month period.

This oscillation began to slow down in the early 2000s, reaching a historical minimum since 2017. And between 2017 and 2020, “it’s gone,” says Professor Leonid Zotov.

Observations from radio telescopes also show that the oscillations have decreased in recent years.

A final possibility , which scientists think is plausible, is that nothing concrete has changed in or around the Earth. It could only be that long-term tidal effects work in tandem with other cyclic processes to produce a temporary change in the Earth’s rotation rate.

DO WE NEED ‘ONE SECOND JUMP’?

Accurately understanding the Earth’s rotation is crucial for a wide range of applications – navigation systems like GPS wouldn’t work without it. Additionally, timekeepers insert leap seconds into our official time scales every few years to ensure they don’t get out of sync with our planet.

If the Earth moves to even longer days, we may need to incorporate “a leap second” – which is unprecedented and could completely destroy the global Internet!

This one-second leap is the jump needed to synchronize the time of the most accurate atomic clock in the world with the Earth’s rotational speed.

However, the need for leap seconds is considered unlikely right now. For now, we can welcome the news that – at least for a while – we are all getting a few extra milliseconds a day.

Although the Earth’s rotation speed does not change much in our daily lives, it is important to keep track of it so that the atomic clock can remain accurate to coordinate precisely with GPS and Earth observation satellites.

Article using source: Scitech Daily, Business Insider