The Late Lunar Dynamo
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Where
Dr. Sonia Tikoo
Assistant Professor
Rutgers University
It has been known since the Apollo era that the lunar rocks and crust are magnetized. Until recently, it was unclear whether the magnetizing fields were generated by a dynamo or by processes external to the Moon. New paleomagnetic and spacecraft measurements strongly indicate that much of this magnetization is the product of an ancient core dynamo. Between at least 4.25 and 3.56 billion years ago (Ga), the dynamo produced surface fields with intensities similar to that of the present Earth. The field then declined by at least an order of magnitude by ~3.3 Ga. The dynamo may have persisted in a weakened state beyond 2.5 Ga. When the dynamo ultimately ceased remains unknown. The mechanisms for sustaining such an intense and long-lived dynamo are uncertain but may include mechanical stirring of the core by the mantle and thermochemical convection from core crystallization.
Host: Dr. Michael Sori