Ancient Judean jars can offer insights into the Earth’s magnetic field fluctuations, a new study suggests. The study was conducted in Israel, measuring the position of the microscopic magnetic minerals found in the clay, influenced by the Earth’s magnetic field.
Our magnetic field is generated by melted iron found in Earth’s core. The field protects our planet from destructive solar flares and from cosmic radiation. Some scientists found that our planet lost at least 10 percent of the strength of its magnetic field and that the magnetic field could be lost in the future.
But the new results obtained from the Israeli study suggests this isn’t the case. The researchers observed the tiny magnetic minerals found in the clay. As the jars were heated, the minerals, which were influenced by our magnetic field, swiveled and ultimately froze, revealing the state of the field through the years. “It’s kind of like a tape recorder,” said Ben-Yosef, an archeologist and one of the authors of the new study. The study got published in the journal Proceedings of the National Academy of Sciences.
The researchers can see what happened to the field very accurately because as different rulers rose, the jars were stamped with different royal seals. They were used as containers for olive oil and wine, which were sent to the rulers as a tax payment. Since the region saw lots of political instability in the past, the researchers can narrow down the records to about 30 years.
For instance, Assyrians destroyed Judea in 701 B.C., changing the tax seal. This made Ben-Yosef and his colleagues able to identify what happened with Earth’s magnetic field between 730 B.C.E. to 700 B.C.E.
67 ancient jars were studied in total, dating from the late 8th century B.C. to the late 2nd century B.C. The results showed that the field behaved “choppier” than expected.
It was strongest during the late 8th century B.C, doubling its strength compared to the intensity it has today. During the 8th century B.C, the field was the strongest in the last 10,000 years, according to the researchers. It lost its intensity in just 30 years, during 732 B.C.E. Ben-Yosef assures that those fluctuations are not a cause for concern because our core fluctuates regularly. This is something normal, and not something that could mean the core is getting weaker.