[1] The huge amount of data acquired by Mars Global Surveyor during its mapping period provides a unique opportunity to reassess the paleomagnetic pole positions of Mars previously determined on the basis of the limited low-altitude magnetic data. We identify nine small and isolated magnetic anomalies on the basis of the global magnetic maps and model each anomaly using a vertical prism of elliptical cross section. Both highaltitude (360-430 km) and low-altitude (100-200 km) magnetic data are used simultaneously. We calculate a paleomagnetic pole position assuming that the body is magnetized by a dipole core field. Although the new pole positions do not cluster as closely as the old ones, the new cluster overlaps the older cluster. The clustering suggests that Mars' rotation axis has likely wandered by $50°-60°in the last $4 Gyr. The number of north and south poles in the cluster suggests at least one reversal of the core field during the time the source bodies acquired magnetization.

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The analysis of the Lunar Prospector magnetic data over South Pole Aitken basin reveals two categories of magnetic anomalies with distinctly different polarities. Modeling the anomalies in terms of vertical prism source bodies shows two separate true polar wander paths of the Moon. One is driven by the giant surface mass deficiency resulted from the formation of the South Pole Aitken basin and the other by the giant surface mass concentrations (mascons) formed inside the large impact basins, such as Serenitatis and Imbrium, and a vast volcanic deposit on Procellarum Terrane. A total of ~100° true polar wander path suggests that the source bodies are formed and magnetized during a long period. Moreover, the distinctly different polarities of the two categories of the anomalies support the idea that the core dynamo underwent a reversal or shutdown and started up with a different polarity, caused by the latter impacts. The impact‐induced shock pressures of 10–20 GPa traveling inside the lunar core, the appreciable angular momentum transfer to the lunar mantle by the impacting bodies, and the impact‐induced stratification of the core probably reversed the polarity of the core dynamo. We also model the north Crisium magnetic anomaly, extracted from the Lunar Prospector magnetic data. The paleomagnetic pole position obtained for the source body reveals that the north Crisium anomaly belongs to the first category of the anomalies.