NASA Scientists Found Three Causes of Earth’s Spin Axis Drift


The Earth is not perfect when it comes to its rotation and shape. First, our planet is not a perfect sphere and, secondly, when it rotates around its axis, it drifts and wobbles in what is known as the “polar motion.” Now, NASA scientists found three causes of Earth’s spin axis drift.

According to NASA JPL, after basing their study on observational and model-based data covering the whole 20th century, the researchers from NASA found three processes that influence the Earth’s spin axis drift – ice mass loss (primarily in Greenland), glacial rebound, and mantle convection.

“The traditional explanation is that one process, glacial rebound, is responsible for this motion of Earth’s spin axis. But recently, many researchers have speculated that other processes could have potentially large effects on it as well (…) We identified not one but three sets of processes that are crucial,” said first author Surendra Adhikari of NASA’s JPL.

There are three causes of Earth’s spin axis drift, according to NASA scientists

As mentioned above, the first cause of Earth’s spin axis drift is the ice mass loss, especially in Greenland. In this regard, NASA scientists explained that Greenland lost over 7,500 gigatons of ice which, naturally, imbalanced the planet even more as the ice melted in the oceans. While the glaciers melt in Antarctica, as well, the mass loss recorded in Greenland is a more significant contributor to “polar motion.”

Additionally, the glacial rebound is another cause of Earth’s spin axis drift. As that ice melts and dissipates into the oceans, the land is rising back to its initial position, contributing to the planet’s “polar motion.” According to the study, glacial rebound accounts for one-third of the total Earth’s spin axis drift.

The mantle convection accounts for the remaining 33% of the total Earth’s spin axis drift. As reported by the NASA scientists from the US space agency’s JPL, as the mantle heats some pieces of the inner part of our planet start rising and falling influencing the movement of tectonic plates on Earth’s surface.

Although NASA scientists found three causes of Earth’s spin axis, they believe that many more factors influenced the “polar motion” during the history of our planet.


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