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PSJ · 1 DAY AGO
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Scientists Discover Mars Has a Wobble That Changes Over Time

By Space.Fan Editorial Desk

Researchers have found that the Red Planet rotates with a slow, repeating sway that lasts for decades.

Mars seen from orbit showing its red and rocky surface.
Image · Space.Fan

The Drop

For a long time, we thought of Mars as a that just spun like a steady top. However, by looking at years of data from robots like the InSight lander and several orbiters circling the , scientists have found something new. Mars actually has a slight wobble that changes over the course of about 26 years. To figure this out, the team tracked how Mars moves in space very precisely. They combined information from older missions like Viking and Pathfinder with data from newer orbiters and the InSight lander. By comparing where these machines were at different times, they could measure the position of the 's prime meridian—the imaginary line used to define longitude—with incredible accuracy. The researchers discovered that the way Mars spins is not perfectly fixed. Instead, the experiences a slow oscillation, or back-and-forth shift, in its rotation. This movement is very small, but it is enough to show that the internal parts of the might be shifting or that other forces are at play over long periods.
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Why It Matters

Understanding how Mars rotates helps scientists build better maps and navigate spacecraft more safely. If we do not know exactly where a landing spot is on the surface, we might miss our target by a few meters. Beyond navigation, this discovery helps us learn more about what is happening inside the . The way a wobbles can give clues about its core, mantle, and even how its atmosphere changes with the seasons.
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The Catch

While this study gives us a better picture than ever before, the data still has limits. The findings are based on a model that accounts for changes over the last several decades, but it relies on blending data from many different missions that used different technology. Scientists are still working to narrow down exactly what is causing the 26-year cycle.

Put That in Perspective

In the past, we relied mostly on orbiters to see how Mars turned. Now, by adding data from ground-based landers like InSight, scientists have made their measurements four times more precise for rotation speed. This is a big step toward creating a perfect map of the planet that will be accurate for years to come.

Source September 19, 2026
Alex S. Konopliv, Ryan S. Park, Sebastien Le Maistre, Marie Yseboodt, Rose-Marie Baland
Jet Propulsion Laboratory, Royal Observatory of Belgium, Université Catholique de Louvain·The Planetary Science Journal·10.3847/PSJ/ae9ba7

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