After accelerating in 2020, the rotation of the earth has settled down. However, timekeepers say that “negative leap seconds” may still be needed in the next decade.
On average, each Earth The day includes 86,400 seconds. However, the rotation of the earth is not perfect. It always changes slightly due to the movement of the core, sea and atmosphere. Coordinated Universal Time (UTC) is the official international timekeeping method and is based on the atomic clock. Atomic clocks measure time by the movement of electrons. atom It is cooled to absolute zero. Atomic clocks are accurate and immutable.
Therefore, if the rotation of the earth and the atomic clock are not perfectly synchronized, something must be given. If the astronomical time based on the Earth’s rotation deviates from UTC by more than 0.4 seconds, UTC will get the adjustment in the form of “leap seconds”. Leap seconds may be added, as it last happened on New Year’s Eve 2016. This is when seconds are added to 23 hours 59 minutes 59 seconds on December 31st. Scientists have added leap seconds on average about every 18 months since 1972.NS National Institute of Standards and Technology (NIST).
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Subtracting seconds is called a negative leap second. There has never been a negative leap second in international timekeeping, but by 2020 it is more likely that it will be needed. That year, the Earth’s rotation accelerated, breaking the 28-time previous record in the shortest day set in 2005. The shortest day in 2020 occurred on July 19, when the planet completed its rotation 1.4602 milliseconds faster than an average of 86,400 seconds.
Now according to Date and time, The rotation of the earth is mellow. The first half of 2021 was still fast, with an average daily time of 0.39 ms shorter than in 2020. However, from July 1st to September 30th, the number of days was on average 0.05ms longer than in 2020.
What that means is that, according to time and date, the Earth is no longer accelerating its rotation. However, it is still spinning faster than average. Based on the current speed of rotation, a negative leap second may be required in about 10 years.The final decision belongs to International Earth Rotation and Reference System Service (IERS) In Paris.
Of course, the planet may have other ideas. It is quite possible that the Earth’s rotation will slow down again, and perhaps instead of subtraction, we will need to add seconds in the next few years. You can’t predict that. Scientists are not sure what causes the long-term changes in the Earth’s rotation.
“We’ve been trying to model things internally for more than two years,” Nick Stamatakos, one of the IERS Board representatives at the US Naval Observatory, told Time and Date. “But I had a problem predicting more than 6 months or a year ahead.”
Originally published in Live Science
The rotation of the earth has slowed down. However, it may still require negative leap seconds.
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