On June 22, Time and Date recorded the shortest day on Earth. Despite the data, some scientists say the continuous acceleration has strangely slowed down after 2020. Although some scientists' assumptions seemed contradictory to the latest record, they provided several reasons why it is possible.
According to Science Alert, Earth's rotation has slowed down over millions of years due to friction brought on by the moon's tides. It lengthens each day by 2.3 milliseconds every century as a result of this process. In the same article, it was emphasized that the day on Earth was just approximately 19 hours long a few billion years ago. It is five hours earlier than today's clock hours.
Another factor scientists see is the long-term trajectory that appears to have changed since 2020, from shortening to extending. Over 50 years, there has never been a change like this. Yet, it is unclear why these changes occurred. Some assumptions that try to explain such changes include the back-to-back La Nia incidents, weather system changes, and the ice sheets' steady rate of melting.
The Chandler wobble, a small deviation in the Earth's rotating axis with a period of around 430 days, is thought by scientists to be responsible for the planet's recent, enigmatic change in rotational speed. Radio telescope observations also indicate that the wobble has decreased recently, which implies that they may be related.
The final hypothesis is that nothing specific has changed on or around Earth. It could just be that long-term tidal impacts and periodic processes are interacting to change the Earth's rotational speed momentarily.
Previous Theory on Earth's Speed Slowing Down
In 2018, Forbes published an article explaining why the Earth is mysteriously slowing down. One theory was the involvement of the Earth's outer core. It is the liquid metal layer that circulates beneath the solid lower mantle.
It is hypothesized that the outer core occasionally sticks to the mantle, disrupting its flow. This would change the Earth's magnetic field and cause a brief blip in the planet's rotation. The data showed a strong correlation but not a connection. As a result, it is unclear to experts if the increase in earthquakes is related to this change in the Earth's rotation.
Although there is no direct connection between the two, the pattern over the past century points to 2018 being a very busy earthquake year. There will often be 15 to 20 major earthquakes with a magnitude of 7.0 or greater. However, there are typically 25-30 big earthquakes each year during the observed increase in earthquakes that coincides with the fifth year of Earth's rotation slowdown.
A precise understanding of the Earth's rotation rate is necessary for many applications; without it, GPS and other navigational systems would not work. Additionally, timekeepers add leap seconds every few years to keep our official timelines in sync with our planet.
Implementing a negative leap second might be necessary if the Earth changes to even longer days.
The requirement for negative leap seconds is now thought to be unnecessary. At the moment, if the theories are true, we may celebrate having a few extra milliseconds each day, at least for the time being.
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