PT  - JOURNAL ARTICLE
AU  - Mighani, Saied
AU  - Wang, Huapei
AU  - Shuster, David L.
AU  - Borlina, Cauȇ S.
AU  - Nichols, Claire I. O.
AU  - Weiss, Benjamin P.
TI  - The end of the lunar dynamo
AID  - 10.1126/sciadv.aax0883
DP  - 2020 Jan 01
TA  - Science Advances
PG  - eaax0883
VI  - 6
IP  - 1
4099  - http://advances.sciencemag.org/content/6/1/eaax0883.short
4100  - http://advances.sciencemag.org/content/6/1/eaax0883.full
SO  - Sci Adv2020 Jan 01; 6
AB  - Magnetic measurements of the lunar crust and Apollo samples indicate that the Moon generated a dynamo magnetic field lasting from at least 4.2 until <2.5 billion years (Ga) ago. However, it has been unclear when the dynamo ceased. Here, we report paleomagnetic and 40Ar/39Ar studies showing that two lunar breccias cooled in a near-zero magnetic field (<0.1 μT) at 0.44 ± 0.01 and 0.91 ± 0.11 Ga ago, respectively. Combined with previous paleointensity estimates, this indicates that the lunar dynamo likely ceased sometime between ~1.92 and ~0.80 Ga ago. The protracted lifetime of the lunar magnetic field indicates that the late dynamo was likely powered by crystallization of the lunar core.