Mysteriously magnetic rocks collected on Apollo mission finally get an explanation

[Grim Reaper 6]

Scientists may have finally come up with an explanation for one of the Apollo program's most enduring mysteries: why some of the rocks brought back from the lunar surface appear to have been formed inside a magnetic field as strong as that on Earth. Magnetic fields are produced inside planetary bodies by the churning movement of material in planets’ electrically conductive molten cores. But today the interior of the non-magnetic moon is quite different from Earth's magnetized innards — it's dense and mostly frozen, containing only a small outer core region that is fluid and molten. Scientists believe that the moon's insides cooled fairly quickly and evenly after it formed around 4.5 billion years ago, meaning it doesn't have a strong magnetic field — and many scientists believe it never did.

How then, could some of the 3 billion-year-old rocks retrieved during NASA's 1968-to-1972 Apollo missions look like they were made inside a geomagnetic field powerful enough to rival Earth's, while others had barely any magnetic signatures at all?

Mysteriously magnetic rocks collected on Apollo mission finally get an explanation | Live Science