Early Lunar Magnetism

  title={Early Lunar Magnetism},
  author={Ian Garrick‐Bethell and Benjamin P. Weiss and David L. Shuster and Jennifer Buz},
  pages={356 - 359}
It is uncertain whether the Moon ever formed a metallic core or generated a core dynamo. The lunar crust and returned samples are magnetized, but the source of this magnetization could be meteoroid impacts rather than a dynamo. Here, we report magnetic measurements and 40Ar/39Ar thermochronological calculations for the oldest known unshocked lunar rock, troctolite 76535. These data imply that there was a long-lived field on the Moon of at least 1 microtesla ∼4.2 billion years ago. The early age… 
Moonstruck Magnetism
It is proposed that many of the Moon's magnetic anomalies originate from highly magnetic deposits of a giant asteroid that collided with the Moon early in its history.
Persistence and origin of the lunar core dynamo
Analysis of two 3.56-Gy-old mare basalts demonstrating that they were magnetized in a stable and surprisingly intense dynamo magnetic field of at least ∼13 μT extend the known lifetime of the lunar dynamo by ∼160 My and indicate that the field was likely continuously active until well after the final large basin-forming impact.
The end of the lunar dynamo
P paleomagnetic and 40Ar/39Ar studies showing that two lunar breccias cooled in a near-zero magnetic field at 0.44 ±0.01 and 0.91 ± 0.11 Ga ago indicates that the lunar dynamo likely ceased sometime between ~1.92 and ~0.80 Ga ago.
Decline of the lunar core dynamo
Thermal core‐mantle coupling in an early lunar dynamo: Implications for a global magnetic field and magnetosphere of the early Moon
A theoretical model suggests a short‐lived lunar dynamo driven by a mantle overturn forming crustal thickness dichotomy, while the lunar paleomagnetic data and crustal magnetic fields suggest both of
A Long-Lived Lunar Core Dynamo
Paleomagnetic, petrologic, and 40Ar/39Ar thermochronometry measurements on the 3.7-billion-year-old mare basalt sample 10020 imply that a lunar core dynamo existed between 4.2 and 3.
An episodic high-intensity lunar core dynamo
Magnetizations within lunar rocks indicate that the ancient Moon produced an internally generated magnetic field 1 – 4 . Yet the long-lived field intensities of 40–120 μT inferred for the ancient
An Impactor Origin for Lunar Magnetic Anomalies
It is shown that the most prominent grouping of anomalies can be explained by highly magnetic extralunar materials from the projectile that formed the largest and oldest impact crater on the Moon: the South Pole–Aitken basin.
The history of the core dynamos of Mars and the Moon inferred from their crustal magnetization: a brief review
The core dynamos of Mars and the Moon have distinctly different histories. Mars had no core dynamo at the end of accretion. It took ∼100 Myr for the core to create a strong dynamo that magnetized the


Magnetism of the Moon - a lunar core dynamo or impact magnetization?
Surface and satellite observations of lunar crustal magnetization and the remanent magnetization of the lunar samples returned by the Apollo missions of 1969–72 provide evidence for past magnetic
The origin of lunar palaeomagnetism
THE new determination of magnetic field anomalies over part of the Moon's surface from Apollo 15 and 16 subsatellite magnetometer data has recently been interpreted1 in terms of magnetised areas of
An early lunar core dynamo driven by thermochemical mantle convection
It is shown that a transient increase in core heat flux after an overturn of an initially stratified lunar mantle might explain the existence and timing of an early lunar dynamo.
Early results from the magnetic field experiment on lunar Explorer 35
Explorer 35 was injected into a selenocentric orbit on July 22, 1967. Analysis of measurements near periselene (800 km from the lunar surface) while the moon is within the geomagnetic tail suggests
Magnetic Studies of Lunar Samples
The remanent magnetismn of a lunar type C breccia sample includes a large viscous component with a time constant of several hours, and a high coercivity remanence, possibly acquired by impact
Martian Surface Paleotemperatures from Thermochronology of Meteorites
It is found that the nakhlites have not been heated to more than 350°C since they formed and that for most of the past 4 billion years, ambient near-surface temperatures on Mars are unlikely to have been much higher than the present cold (<0°C) state.
Apollo 12 Magnetometer: Measurement of a Steady Magnetic Field on the Surface of the Moon
Surface gradient measurements and data from a lunar orbiting satellite indicate that this steady field is localized rather than global in its extent, suggesting that the source is a large magnetized body which acquired a field during an epoch in which the inducing field was much stronger than any that presently exists at the moon.
Lunar evolution: The first 600 million years
From a stepwise-heating experiment to neutron-irradiated samples of whole rock and a plagioclase separate, we have determined an 40Ar - 39Ar age of 4.26 ± 0.02 G.y. for the Apollo 17 troctolite
Magnetic fields of lunar multi‐ring impact basins
Abstract— We survey the magnetic fields of lunar multi‐ring impact basins using data from the electron reflectometer instrument on the Lunar Prospector spacecraft. As for smaller lunar craters, the
Methods in Rock Magnetism and Palaeomagnestism
During the last 30 years the study of the magnetic properties of rocks and minerals has substantially contributed to several fields of science. Perhaps the best known and most significant advances