Named the shortest day of the year

On July 10, 2025, the day length decreased by 1.36 milliseconds - exactly that much time was missing from a complete 24-hour Earth rotation cycle. This was reported by the scientific publication Space.com, citing data from international services that track the planet's rotation speed using atomic clocks.

Usually a day lasts exactly 86,400 seconds, but in recent years scientists have increasingly recorded microscopic deviations from this norm. According to specialists' calculations, on July 5, 2025, Earth also accelerated its rotation - then the rotation around its axis completed 1.25 milliseconds earlier than usual. On July 22, a similar anomaly is also expected: the day may shorten by 1.34 milliseconds.

The absolute record was recorded on July 5, 2024. Then the planet completed a full rotation 1.66 milliseconds faster than standard time. Such measurements became possible since 1973 - the moment high-precision atomic clocks capable of tracking the slightest fluctuations in Earth's rotation were implemented.

Although the reduction of the day by thousandths of a second is not felt at the everyday level, scientists are closely monitoring this trend. According to specialists, the acceleration of Earth's rotation may indicate complex processes occurring in its interior.

"The reason for this acceleration has not been revealed," commented Leonid Zotov, a leading specialist in Earth rotation.

He noted that possible explanations could be the redistribution of masses inside the planet, tectonic processes, or changes in the core. Zotov also added that in the future, Earth may begin to slow down again, as its rotation speed is unstable and depends on a whole complex of internal and external factors.

At the moment, the reduction in day length does not affect everyday life, but in the future, it may require adjustment of Coordinated Universal Time (UTC), which is currently maintained by adding or excluding so-called "leap seconds".