This month, Earth has been spinning faster than usual, resulting in the shortest day of the year being recorded on July 10. The planet completed a full rotation 1.36 milliseconds faster than the standard 24-hour period. Similar occurrences are expected on July 22 and again on August 5, marking a trend of increasingly shorter days.
The concept of Earth’s rotation period is referred to as the Length of Day (LOD), which ideally lasts exactly 24 hours. However, the LOD can fluctuate by tiny amounts—measured in milliseconds—due to several natural factors. These variations are so minute that they often go unnoticed in daily life, but they are precisely recorded using advanced instruments like atomic clocks.
Historical data shows that prior to 2020, the shortest day ever recorded was 1.05 milliseconds shorter than the standard 24 hours. Since then, the Earth’s rotation speed has gradually increased, surpassing that previous record multiple times. On July 5, 2025, the planet’s rotation sped up even more, setting a new record with a day 1.66 milliseconds shorter than the usual duration.
Scientists attribute these subtle changes in Earth’s spin to complex interactions between the planet’s interior, atmosphere, oceans, and external gravitational forces such as the Moon and the Sun. Factors like earthquakes, climate changes, and variations in ocean currents can also influence how quickly Earth rotates.
While a difference of a few milliseconds may seem insignificant, it has important implications for fields that require precise timekeeping, including satellite navigation, telecommunications, and global positioning systems. To maintain synchronization with Earth’s rotation, the International Earth Rotation and Reference Systems Service (IERS) occasionally adds leap seconds to Coordinated Universal Time (UTC) to compensate for these variations.
The faster spin of Earth this month is a fascinating reminder of the dynamic nature of our planet. As research continues, scientists hope to better understand the causes behind these changes and predict future fluctuations in the length of our days.
