The Earth Is Expanding Its Days, But We Aren’t Sure Why

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The duration of a day has been steadily increasing, as measured by atomic clocks and precise astronomical observations. Researchers have no explanation. Exact measurements demonstrate that the rotation of the Earth has been strangely slowing down since 2020, extending the length of the day.

Using a combination of atomic clocks and precise astronomical measurements, scientists have determined that the duration of a day is gradually increasing. Why this is happening is a mystery to scientists. This has profound repercussions for our timekeeping as well as other precise technologies that control our lives today, such as GPS.

The rate at which Earth spins on its axis has increased during recent decades. The length of a day is directly affected by this, therefore the current tendency has the effect of shortening our days. Specifically, in June of 2022, we recorded the shortest day in the last fifty years or so.

Despite this unprecedented rate of progress, there has been a strange reversal to a slower pace after 2020. The longer days seem to have returned for some cause that has yet to be determined.

Despite what the timers on our phones say, the Earth’s rotation does not always take precisely 24 hours. In some cases, millions of years may pass before these shifts become noticeable, while in others, they may happen in a matter of seconds. Natural disasters like earthquakes and hurricanes may also play a part.

Over millions of years, Earth’s rotation has slowed due to frictional factors related to the tides generated by the Moon. This effect lengthens each day by around 2.3 ms per 100 years. A day on Earth was just approximately 19 hours long a few billion years ago.

Over the last twenty thousand years, another mechanism has been at work in the opposite direction, causing Earth’s rotation to speed up. As the polar ice caps melted towards the end of the last ice age, surface pressure dropped and the mantle of the Earth began slowly creeping toward the poles.

When this mass of mantle gets closer to Earth’s axis, the globe spins faster, like a ballerina does when she brings her arms closer to her body, the axis around which she spins. In this way, each day has been cut down by around 0.6 milliseconds every century.