How Sampling Bias Could Have Implied a False History of the Moon

Collecting samples to support good, reliable science is challenging at the best of times—let alone when it's on the surface of the Moon.

Research published Thursday in the journal Nature Geoscience suggests that theories of the Moon's geological history were influenced by unrepresentative sampling. In other words, they believe that the rocks around the Apollo landing sites are much richer than average in a few rare types of rock.

By incorrectly assuming that these rocks were common across the Moon, prior researchers may have inferred the wrong lunar history from them.

The issue comes down to the strength of the Moon's magnetic field during its early history, from about 3.5 to 4 billion years ago. The small size of the Moon's core led to the natural prediction that it would produce a weak field at the time (and at every other time), but the ...