Gravity data suggests Ceres' poles experience a reorientation

Oct. 8 (UPI) -- Ceres, the solar system's innermost dwarf planet, features a wandering pole, new research confirms.

Using gravity data collected by NASA's Dawn mission, researchers at the Planetary Science Institute were able to map density variations in Ceres crust, revealing topographical anomalies best explained by a polar reorientation.

"The topography shows the remnants of an equatorial ridge compatible with the position of the paleo-equator," researchers wrote in a paper published this week in the journal Nature Geoscience.

The axis around which a planetary body spins affects the density of the body's outer layers, including the crust. When the axis shifts and poles reorient themselves, crustal or topographical anomalies can emerge.

On Ceres, scientists found evidence of a former equator near a region known as Ahuna Mons. The positioning of the former equator suggests Ceres' pole reoriented itself 36 degrees.

The topographical analysis suggests Ceres' pole took an indirect path from its previous orientation to its current orientation.

"A multi-step reorientation could mean that the equatorial density anomaly was still evolving during the reorientation, and this could be because the crust and mantle were weakly rotationally coupled, allowing the crust to start reorienting while the mantle would lag behind," Pasquale Tricarico, senior scientist at the Planetary Science Institute, said in a news release. "If crust and mantle are allowed to shift with respect to one another, that could point to a layer of reduced friction between crust and mantle, and one of the possible mechanisms to reduce friction could be an ancient water ocean beneath the crust."

Scientists have previously observed the remnants of an equatorial ridge of Iapetus, suggesting the moon of Saturn experienced a similar a reorientation.