Earth will speed up its rotation on July 22!

Creating the second shortest day in history.

On July 21 (US time), US Space News published an article.

Earth will complete a full rotation in slightly less time than usual on Tuesday, July 22, making this day one of the shortest days on record.

This will be just 1.34 milliseconds faster than standard time, which people will not notice at all.

But it is part of a puzzling trend in Earth's rotational behavior in recent years.

If this trend continues, by 2029, one second may need to be subtracted from atomic clocks, which has never happened before.

The speed of Earth's rotation is not fixed.

Long ago, a day was much shorter than the 24 hours we are used to now.

According to a study, during most of Earth's early history, a day was about 19 hours, due to the balance between solar atmospheric tides and lunar oceanic tides.

However, over long geological periods, the days on Earth have become longer. The main reason is the tidal friction of the moon, which causes the moon to gradually move away from Earth.

So why the sudden reversal?

From 1973 (the invention of atomic clocks) to 2020, the longest recorded day was 1.05 milliseconds shorter than 24 hours.

However, since 2020, the Earth has broken its own speed records multiple times, with the shortest day measured on July 5, 2024, when the Earth rotated 1.66 milliseconds faster than usual.

There will be more such days in the future.

A 2024 study showed that melting polar glaciers and rising sea levels, even China's Three Gorges Dam, may be affecting Earth's rotation.

However, this redistribution of mass may not be the cause of the acceleration, but rather a mitigating factor.

A more likely culprit is something beneath our feet — the slowing rotation of the Earth's liquid core, which may redistribute angular momentum in a way that causes the mantle and crust to rotate slightly faster.

Leonid Zotov, a leading expert on Earth's rotation from Russia's National University, said: "The reason for this acceleration is still unclear, and most scientists believe it is something inside the Earth."

An American netizen, Angel Girl, said:

July 22 is my birthday, which will be shorter than others', Earth says: "Happy birthday... Oh, let's get it over with!"

Original: https://www.toutiao.com/article/1838299269974027/

Statement: This article represents the views of the author.