Earth’s Rotation Shortens in July and August, Defying Expectations
Recent observations indicate that Earth's rotation is expected to speed up during July and August, countering the long-term slowdown trend. While specific causes remain unclear, experts note that traditional models, involving oceanic, atmospheric, and tidal effects—including the Moon’s gradual retreat—do not fully explain this acceleration.
Historically, Earth’s rotation has varied significantly over hundreds of millions of years. Fossilized coral records reveal that around 440 million years ago, our planet completed approximately 420 rotations per year, suggesting a much faster spin than today.
Today, Earth completes just over 365 rotations annually, a pace gradually slowed by tidal interactions with the Moon. Factors influencing Earth's rotation include sea level changes, internal Earth dynamics, and seismic events. Notably, large earthquakes can alter the planet’s mass distribution, slightly speeding up or slowing down its rotation.
For example, the 2011 magnitude 9.0 earthquake off Japan shifted Earth's axis and shortened days by about 1.8 microseconds. In recent years, and unexpectedly, the Earth's rotation has been accelerating, leading to shorter days, 'leap seconds' being omitted since 2016, and record-breaking brief days observed in 2020 and 2024.
In July and August 2025, days are predicted to be shorter by roughly 1.3 to 1.5 milliseconds. Scientists are puzzled by this reversal of the long-term trend. While the Moon's recession from Earth typically slows rotation, the recent acceleration suggests other internal or surface factors at play—not yet fully understood. Current monitoring by international space agencies continues to track these changes closely.
Overall, this unexpected trend highlights the complexity of Earth's dynamic systems and invites further research to understand the underlying mechanisms driving these rotational variations.
