Carissimi Associati SGI,
Carissimi Soci Società Associate,
su indicazione del Prof. Rodolfo Carosi (Università di Torino e Presidente SGI) vi segnaliamo l'ultimo podcast di Geology Bites (Conversations about geology with researchers making key contributions to our understanding of the Earth and the Solar System):
Sonia Tikoo (Department of Geophysics at Stanford University) on the Moon's Magnetic FieldDi seguito troverete il messaggio dell'ideatore, Oliver Strimpel, e il link al sito web di Geology Bites.
Cordiali saluti,
La Segreteria SGI
Hello, listeners,
I just released an episode on the Moon's magnetic field with Sonia Tikoo who is an Assistant Professor at Stanford University.
By studying the samples returned from the Moon by the Apollo mission and, more recently, by China's unmanned Chang'e 5 and Chang'e 6 as well as surveys by spacecraft orbiting the Moon, we have determined that the Moon started out with a field about as strong as today's terrestrial field, but that it weakened starting about 3.5 billion years ago, petering out around 1.5 billion years ago.
In the podcast, Tikoo explains the very diverse set of hypothesized mechanisms that might generate the strong early field and the weak long-lasting later field. One challenge is to reconcile the strong field with physical considerations that tell us that the Moon did not have the energy to sustain such a field. To overcome this problem, she has proposed that the Moon had an intermittent field, strong enough to leave rocks of the appropriate age strongly magnetized, but, on average, requiring much less energy than a sustained field. Such a field would be consistent with observations to date.
I hope you enjoy listening.
Oliver
geologybites.com