Ancient Jars Hold Clues About Changes In Earth’s Magnetic Field

Posted: Feb 15 2017, 5:30am CST | by , Updated: Feb 15 2017, 5:42am CST, in News | Latest Science News

 

Ancient Jars Hold Clues About Change in Earth’s Magnetic Field
Stamped ancient jar handle. Credit: Oded Lipschits
 

Researchers report that the jar handles revealed a gradual reduction in magnetic field' strength over the course of the six centuries under study

Earth’s magnetic field acts like a giant shield to block deadly cosmic radiations and to protect us from their harmful effects and without it, life as we know it, could not exist on Earth. However, Earth’s magnetic field has proven to be a complex phenomenon to study over the years. Constant changes in this protective shield on various time scales ranging from decades to millennia and longer have made it nearly impossible for researchers to understand geomagnetic field’s behavior in the past and to predict its intensity in the future.

Recently, researchers have examined dozens of jar handles collected from excavations of Judah, an Iron Age kingdom encompassing modern-day Israel and Palestine that flourished around 7th century BCE and drew some interesting conclusions.

Researchers believe that these jars are a good place to collect information about the past magnetic field. Like volcanic rocks, clay jars record the strength of the magnetic field as they fired in kilns and then cooled. 

By examining iron oxide particles embedded in the clay, researchers determined the accurate age of jars, which assisted them in measuring Earth’s magnetic field over time. By repeating this process for all jar handles created between the 8th and 2nd centuries BCE, the team was able to reconstruct the magnetic field intensities timeline.

Jar handles revealed a gradual reduction in the strength of magnetic field over the course of the six centuries under study and there were also times when its strength either increased or weakened. For example, magnetic field’s strength spiked at the end of the 8th century BEC and then reduced again afterwards, losing approximately 27 percent of its strength.

Earth’s magnetic field has been weakening, losing about 10 percent of its strength over the past 180 years. But new data suggests that this reduction could also be periodic and magnetic field could regain strength in coming years.

Next, researchers are hoping to better understand the nature of the geomagnetic field and to answer some questions, such as why fluctuations and changes in direction occur.

The findings of the study were published in journal PNAS.

 

 

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Hira Bashir covers daily affairs around the world.

 

 

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