Scientists confirm that Earth’s rotation speeds up this summer, with 9 July 2025 marking the shortest day ever recorded. According to the International Earth Rotation and Reference Systems Service (IERS), several days this season- 9 July, 22 July, and 5 August- will be 1.3-1.6 milliseconds shorter than the standard 24-hour day.
Researchers explain that this acceleration is unprecedented in modern history, and it can be measured precisely thanks to atomic clocks. The shortest day previously logged was on 5 July 2024, when Earth rotated 1.66 milliseconds faster than the norm.
While it might not seem like it, this subtle change matters. Even slight shifts in Earth’s rotation can disrupt satellite navigation, telecommunications, and the global timekeeping infrastructure. If the trend continues, timekeeping bodies may need to apply a negative leap second- removing a second from Coordinated Universal Time (UTC)- for the first time, perhaps as early as 2029, especially if Wednesday doesn’t remain the shortest day ever.
Experts point to the moon’s gravitational pull- especially when the moon sits furthest from Earth’s equator- and internal Earth dynamics (like shifts in the core, ocean currents, or ice mass distribution) as possible causes. While this isn’t cause for alarm- it won’t be noticeable in daily life- it is a significant sign of our planet’s ever-changing behaviour.
As Earth’s rotation speeds up, scientists will closely monitor timekeeping systems to mitigate any technical fallout.
Also read: Eratosthenes & Skytrek join forces for space innovation
For more videos and updates, check out our YouTube channel.
