Gravitational Tug-of-War Inside Earth Is Changing the Length of Our Days
The model best matched records when gravitational torque dominated, suggesting competing forces from Earth’s core can shift the day by several milliseconds.
- University of Alberta researchers found that interactions between Earth's core and mantle cause subtle, decadal fluctuations in the planet's rotation, according to a new study published in Nature.
- Geophysicists Huifeng Zhang and Mathieu Dumberry modeled three competitive mechanisms—gravitational, electromagnetic, and topographic coupling—that battle to speed up or slow down Earth's rotation.
- Their model reveals gravitational torque as the dominant force, while electromagnetic and mechanical effects push opposite, explaining observations from the early 1970s to 2021.
- "What I find particularly exciting is that these different pieces of information can come together to provide a more coherent picture of Earth's deep interior," Zhang explained.
- Zhang is now investigating whether these same mechanisms could explain an observed six-year cycle in the length of Earth's day, contributing to broader understanding of planetary behavior.
30 Articles
30 Articles
Earth’s day isn’t exactly 24 hours. The reason may lie deep inside the planet
Scientists may have solved why the length of Earth’s day changes by a few milliseconds over decades. Subtle shifts in the inner core appear to tug on the mantle, revealing a surprisingly dynamic world thousands of kilometers beneath our feet.
Why Does the Length of a Day Change?
Earth's rotation is treated as a constant, yet instruments detect fluctuations in the length of a day measured in milliseconds. For three decades, geophysicists attributed these shifts to the fluid outer core; changes in the velocity of its molten metal alter the magnetic field. Because the planet's total angular momentum remains fixed, the 3,000-kilometer-thick mantle compensates for these shifts, forcing the surface to speed up or slow down. T…
A new study shows how the rotation of the earth's core shortens the days. In the interior of the earth, gravity fights against mechanical pull and the force of the magnetic field.
A day does not always last exactly 24 hours. Minuscule variations of a few milliseconds have kept geologists busy for decades. A new study indicates that an underground tug-of-war between the inner core and the mantle influences the planet's rotation speed, causing the length of days to vary.
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