Moon's Tilt Change Over Time

 

 

This illustration shows a cross-section through the Moon, highlighting the antipodal nature of lunar polar volatiles (in cyan), and how they trace an ancient spin pole (green arrow). The reorientation from that ancient spin pole (green arrow) to the present-day spin pole (blue arrow) was driven by the formation and evolution of the Procellarum—a region on the nearside of the Moon associated with a high abundance of radiogenic heat producing elements, high heat flow, and ancient volcanic activity.

 

Credit: James Tuttle Keane, University of Arizona