Overview

• TimeandDate’s July 10 estimates forecast the four shortest rotations of 2025 on July 9, July 10, July 22 and August 5.
• Preliminary figures suggest July 10 may set the shortest day yet, potentially undercutting last year’s −1.66 millisecond record.
• Atomic-clock networks have tracked successive midyear declines in Earth’s day length since 2020, detecting variations measured in milliseconds.
• Scientists including Leonid Zotov say they have no definitive explanation for the planet’s sustained acceleration in rotation.
• Timekeepers are assessing whether to insert a negative leap second to keep UTC aligned with Earth’s rotation and protect GPS accuracy.