Overview

• On August 5, Earth’s solar day is predicted to be up to 1.25 milliseconds shorter than 24 hours, following similar spin-ups on July 9 and July 22.
• Data from atomic clock networks managed by the International Earth Rotation and Reference Systems Service and the U.S. Naval Observatory confirm these unprecedented temporary accelerations.
• Researchers remain uncertain about the root cause but are investigating factors ranging from lunar gravitational effects to core-mantle interactions and atmospheric influences.
• International timekeepers are drafting procedures for what would be the first negative leap second in 2029 to offset the increasing speed of Earth’s rotation.
• Experts warn that sustained accelerations could shift ocean water toward the equator and disrupt human circadian rhythms, with potential impacts on sea levels and public health.