Earth is spinning faster than usual, making the day shorter

Earth's Rotation Acceleration: Earth is experiencing irregular acceleration in its rotation, a mystery that has puzzled scientists. These increases in speed, which have recurred several times in recent years, have not significantly affected our daily lives, but they have not gone unnoticed by the scientific community. Tuesday, August 5, 2025, is expected to see an additional acceleration in Earth's rotation, which will shorten the day by 1.25 to 1.51 milliseconds.

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Data Predictions: These predictions are based on data from the International Earth Rotation and Reference Systems Service (IERS) and the U.S. Naval Observatory. Initial estimates indicated that the day would shorten by 1.51 milliseconds, but this was later updated to 1.25 milliseconds. This represents the third such acceleration in Earth's rotation during the summer of 2025, preceded by two instances on July 10 and 22 of the same year.

Role of IERS: The International Earth Rotation and Reference Systems Service (IERS) is a global body responsible for maintaining Earth's time standards and reference frames, providing accurate data on the planet's rotation and defining the international celestial and terrestrial reference frames relied upon by scientists in their studies.

Shortest Day Recorded: If the initial predictions hold true, August 5, 2025, will become the third shortest day recorded in history, after June 30, 2022, when Earth's rotation accelerated by 1.59 milliseconds, and July 5, 2024, which was faster by 1.66 milliseconds. However, if the predictions are inaccurate, this day might surpass the previous two, becoming the shortest day Earth has experienced in recorded history.

Earth's Cycle: For comparison, Earth typically takes about 86,400 seconds to complete one rotation around its axis. One millisecond is equivalent to 0.001 seconds, so this slight change will not be noticeable to humans and will not affect their daily lives.

What Causes Earth's Rotation to Accelerate?

Potential Causes: There are multiple potential reasons behind Earth's rotational acceleration. The most common theory is that the Moon's current position relative to Earth plays a major role. When the Moon is far north or south of Earth's equator, its gravitational force can influence the planet's rotational speed.

“Earth_rotation.gif” — Source: Wikimedia Commons. License: CC.

Moon's Influence: On August 5, 2025, the Moon will be in a position very far south of the equator, which is believed to cause this slight acceleration in Earth's rotation, and its effect is expected to be short-term on the planet's orbit.

Scientists Cannot Explain This

Scientists' Perplexity: The acceleration of Earth's rotation puzzles scientists, especially since the long-term trend has been the opposite. About 245 million years ago, in the age of dinosaurs, days were an hour and a half shorter than they are today. Since then, Earth's rotation has gradually slowed down, primarily due to the Moon's gravitational pull on Earth's oceans, a phenomenon known as "tidal braking." Scientists have been able to accurately measure this slight deceleration since official records began in 1973.

Possible Explanations: However, recent data has shown an opposite trend towards rotational acceleration. While faster days can be partially explained by the Moon's orbit, science has not found a complete explanation for this shift. A research paper published in "Nature" in 2023 suggested that Earth's inner core may have begun to slow down its rotation around 2010, which could contribute to the acceleration of the planet's outer crust. However, this assumption is still under investigation and has not yet been confirmed.