The Red Planet is wiggling and wobbling as it spins, research in the journal Geophysical Research Letters confirms, and astronomers have no idea why.
Like a toy top that teeters as it loses speed, the poles of Mars are wandering ever-so-slightly away from the planet’s axis of rotation, moving about 4 inches (10 centimeters) off-center every 200 days or so, researchers reported in a study published Oct. 13, 2020. That makes Mars only the second known planet in the universe to exhibit this phenomenon — known as the Chandler wobble — with Earth being the first, according to the American Geophysical Union’s (AGU) news blog, Eos.org.
This wobble — named for astronomer Seth Carlo Chandler, who discovered the phenomenon more than a century ago — is an effect seen in planets that aren’t perfectly round, science writer Jack Lee wrote at Eos. On Earth, the wobble is much more pronounced: Our planet’s poles wander roughly 30 feet (9 m) from its axis of rotation, wobbling in a circular pattern that repeats every 433 days or so.