Early lunar magnetism

Abstract

A new method (Shaw, 1974) for investigating paleointensity (the ancient magnetic field) was applied to three subsamples of a single, 1-m homogeneous clast from a recrystallized boulder of lunar breccia. Several dating methods established 4 billion years as the age of boulder assembly. Results indicate that the strength of the ambient magnetic field at the Taurus-Littrow region of the moon was about 0.4 oersted at 4 billion years ago. Values as high as 1.2 oersted have been reported (Collison et al., 1973). The required fields are approximately 10,000 times greater than present interplanetary or solar flare fields. It is suggested that this large field could have arisen from a pre-main sequence T-Tauri sun.