A clay jar found near Jerusalem used to prove the magnetic field won't kill us. A clay jar found near Jerusalem used to prove the magnetic field won't kill us. This clay jar from an area near Jerusalem was used to study the earth's magnetic field millennia ago. (Photo: Oded Lipschits).

Archaeology proves that Earth's magnetic field won't kill us

Scientists studying 600-year-old pottery prove the geomagnetic field is not going to disappear.

File this one under the "what a relief" column: Clay jars have helped scientists determine the earth's magnetic field isn't going to disappear and kill us all.

Measurements over the last two centuries show that the magnetic field has been weakening, and some believe this eventually means its disappearance altogether. That would create quite a problem considering it protects us humans from deadly cosmic radiation.

But Israeli and American researchers found that it is prone to vast – and fast – fluctuations, and this isn't the first time the magnetic field has rapidly diminished only to eventually rebound.

jar handle found near Jerusalem used to study the earth's magnetic field.A jar handle from Ramat Rahel, near Jerusalem, used by researchers to study Earth's magnetic field. (Photo: Oded Lipschits)

In their recently published study, the researchers from Israel's Tel Aviv University and the University of San Diego in California wrote of how they used clay jars found near Jerusalem that date to between the eighth and second centuries BCE to reach their conclusion.

Clay contains small amounts of a mineral known as magnetite, which, when heated, creates a record of the intensity and alignment of the magnetic field.

The problem that researchers have run up against in the past is dating the clay artifacts to a specific time frame. Fortunately, the people who lived at the time these jars were made used stamps signifying the rulers of the era.

A stamped handle used to study the earth's magnetic fields.A stamped handle from Ramat Rahel, near Jerusalem; the inscription reads "to be sent to the king / belonging to the king, Hebron." (Photo: Oded Lipschits)

Because the stamps can be correlated against other records of the region, the jars could be traced to within 100 years of a specific date.

“The typology of the stamp impressions, which corresponds to changes in the political entities ruling this area, provides excellent age constraints for the firing event of these artifacts,” write the researchers.

The data showed a sharp upward movement in field intensity during the eighth century BCE followed by an overall decline during the following 600-year period. Yet, here we are, (sort of) safe and sound two millennia later.

The results, say the scientists, constitute an “unparalleled record of the geomagnetic field intensity" – and offer some reassurance that we do indeed have a future in front of us.

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