Ceres is the largest body in the main asteroid belt. It was recently explored by the Dawn mission to uncover strong similarities with other icy bodies. The morphological features observed on the surface of Ceres indicate a relatively wide range of water ice concentrations, leading us to investigate the magnitude and distribution of crustal density heterogeneities, and to consider whether they could have caused a reorientation of Ceres. Here, we present three independent and corroborating lines of evidence for the true polar wander of Ceres. Thanks to the global gravity inversion approach applied to the shape and gravity data of Ceres, we find crustal density heterogeneities up to approximately ±0.3 g cm−3, with a prominent positive density anomaly aligned with the equator, in the region of Ahuna Mons. The topography shows the remnants of an equatorial ridge compatible with the position of the palaeo-equator, and indicates that Ceres reoriented by approximately 36°, with the palaeo-pole following an indirect path to the current pole of Ceres. The tectonic patterns generated by the true polar wander are in close agreement with the location and orientation of the Samhain Catenae and Uhola Catenae crustal fractures. These results highlight the complex interior structure and richness of processes taking place in Ceres-scale icy bodies.
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The Ceres shape and gravity data from the Dawn mission are available through the NASA Planetary Data System Small Bodies Node (https://sbn.psi.edu/pds/resource/dawn/). The data that support the findings of this study are available on request from the author.
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I am grateful to the Dawn team for the Ceres data, and to M. Sykes for the long-time encouragement and support. I thank G. Mitri for insightful discussions. This research is supported by NASA grants NNX16AB60G and NNX10AR20G.
The author declares no competing interests.
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Tricarico, P. True polar wander of Ceres due to heterogeneous crustal density. Nature Geosci 11, 819–824 (2018). https://doi.org/10.1038/s41561-018-0232-3
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