Recent analyses indicate that Earth is rotating faster than it has since scientists began recording rotational data in 1973. On July 22, the planet will complete its rotation in just 1.34 milliseconds shorter than the standard 24-hour day. While this variation is imperceptible to humans, it is part of a broader and intriguing trend observed over the last few years.
This acceleration raises the possibility that, if the trend continues, a negative leap second may need to be added to atomic clocks around the year 2029. This would mark a historic first, as such a subtraction has never been implemented before.
Historically, Earth’s rotation has not been constant; in fact, during significant portions of Earth’s early history, a day was approximately 19 hours long due to the balance of solar atmospheric tides and lunar ocean tides. Studies indicate that the moon’s tidal friction has slowly caused it to drift away from Earth over millennia, resulting in longer days.
Interestingly, since 2020, Earth has been breaking records for the shortest days with increasing frequency, with the most significant recent record set on July 5, 2024, at 1.66 milliseconds faster than the typical 24 hours. Looking forward to 2025, predictions have been made for several dates that may see such short days, with July 10 clocking in as the shortest day so far at 1.36 milliseconds less than the 24-hour mark, closely followed by July 22. If conditions remain unchanged, August 5 is also expected to feature a day about 1.25 milliseconds shorter.
While the reasons behind this sudden speed-up in rotation remain somewhat elusive, a study in 2024 proposed that melting polar ice and rising sea levels could be impacting Earth’s spin. However, instead of accelerating rotation, this mass redistribution might actually be stabilizing it. Some scientists suggest that developments in Earth’s liquid core could be a dominant factor affecting these changes in rotation speed.
Leonid Zotov, an expert in Earth rotation from Moscow State University, remarked on the mystery surrounding the current acceleration, emphasizing that ocean and atmospheric models do not account for the rapid increase in rotation speed. He also suggested that Earth’s rotation may soon decelerate again, indicating that this acceleration could potentially be a temporary shift in the ongoing trend toward longer days.
This rapid rotation trend presents an exciting opportunity for further research as scientists strive to better understand the forces at play within our planet. It illustrates the dynamic nature of Earth’s systems, reminding us that our world is always in flux, and while change can sometimes be alarming, it often leads to deeper insights into our planet’s intricate workings.