Jews have been mourning for the Holy Temple – the First that was destroyed by the Babylonians in 586 BCE and the Second that was wiped out by the Romans in 70 CE – for millennia. But besides the recognition that they led to the deaths of many Jews, the exile of those who survived and the purloined sacred objects, we don’t know much about the details, even though Jewish memory is very long.

Now, interdisciplinary researchers at Tel Aviv University (TAU) and the Hebrew University (HU) have discovered the magnetic field that existed during the destruction of the First Temple of Jerusalem 2,606 years ago. The result, just published in the prestigious PLoS (Public Library of Science) journal 10 days after Tisha Be’Av on which the Temples’ destruction is mourned – provides a novel chronological anchor for archaeomagnetic dating – with specific-day accuracy.
Magnetic measurements have proven that during the time of the destruction of the First Temple, another grand building in Jerusalem was burned, probably intentionally, and the floor of the upper story, held up by massive wooden beams, collapsed as a result of the fire.
Archaeological findings that were discovered recently at City of David helped the Israeli researchers, who were joined by colleagues at the Israel Antiquities Authority, include measurement6’s of the earth’s magnetic field in August of 586 BCE.

These groundbreaking findings reveal the immensity of the destruction of Jerusalem by the Babylonians. The PLoS article was based on the doctoral thesis of Yoav Vaknin from TAU’s archaeology department and was conducted in collaboration with Dr. Ron Shaar of the Earth Sciences Institute of HU, Prof. Erez Ben-Yosef, Prof. Oded Lipschits and Prof. Yuval Gadot of TAU’s archaeology department and Dr. Yiftach Shalev of the Israel Antiquities Authority.

Fluctuations in the earth’s magnetic field have been defined by Albert Einstein as one of the five great mysteries of physics. Although the magnetic field that surrounds the earth is invisible, it plays an important role in the life of the planet. It serves as a screen that protects earth from radiation coming in from outer space, enabling life to develop and flourish, and is used as a navigation tool by humans, birds and marine mammals. Despite its importance, however, we know very little about earth’s magnetic field. How is it generated by the planet’s core? How and why does it fluctuate? And how do its fluctuations impact the earth’s atmosphere?

To answer these questions and explain the magnetic field’s mysterious behavior, geophysicists try to reconstruct its behavior during periods before direct measurements began. For this purpose, they can use archaeological findings – such as pottery sherds, bricks, roof tiles and furnaces – that ‘recorded’ the magnetic field as they were burned. These findings contain magnetic minerals that were re-magnetized in accordance with the direction and magnitude of the field at that specific point in time, providing a window onto the history of earth’s magnetic field.
The destruction of Jerusalem, on the 9th day of the Hebrew month of Av in 586 BCE, can serve as an exceptional chronological anchor for archaeomagnetic dating – accurate down to a single day.

In the process of an archaeological excavation currently conducted at the City of David National Park, at a place formerly known as the Givati parking lot, excavators found a grand public structure with a high-quality plaster floor. Shalev and Gadot explained: “We dated the destruction of the structure to 586 BCE based on smashed pottery vessels found on the floor that were typical of the end of the First Temple period. Apart from the broken utensils, we found signs of burning and large quantities of ashes. The findings are reminiscent of the Second Book of Kings, chapter 25 verse 9: “He burned the House of Hashem, the king’s palace, and all the houses of Yerushalayim; he burned down the house of every notable person” (The Israel Bible).

In this particular “important building” that burned down, excavators found a large section of floor that had collapsed from the top story. By measuring the magnetic field recorded in this fragment, the researchers were able to reveal earth’s magnetic field at the time of the fire.

Vaknin sampled fragments of flooring scattered around the site and measured the magnetic field recorded in them at the Paleomagnetic Laboratory of HU’s Institute of Earth Sciences. “The purpose of this study was twofold,” explained Vaknin. “One goal was to rediscover the direction and magnitude of the magnetic field on the day of Jerusalem’s destruction. The other was to understand what the magnetic data recorded in the floor fragments can tell us about the destruction itself.

Even without measuring the magnetic field, he continued, “we could assume that this grand building was destroyed in the event of the destruction of the First Temple. But the magnetic measurements proved that the building had been burned down at a temperature higher than 932 degrees Fahrenheit [500 degrees Celsius], probably intentionally, and that the floor, supported by massive wooden beams, had collapsed during the fire.”

Vaknin added: “We drew this conclusion from the fact that most of the floor’s fragments, cooling down after the collapse, recorded the same magnetic direction – regardless of their arbitrary position after falling from above. We were able to link the destruction of Jerusalem with the recording of earth’s magnetic field, thereby contributing to both geophysical and archaeological research. This is truly extraordinary. The archaeomagnetic method also has implications for future research. If we find a similar destruction layer with similar pottery at another site tomorrow, we will be able to compare the magnetic fields recorded at the two different sites, enabling us to determine whether the other site was also destroyed by the Babylonians.”

Shaar noted that “measuring magnetic data from a floor burned thousands of years ago is no trivial matter. We had to characterize the magnetic particles, understand how the magnetic data was coded in the material and develop measuring techniques enabling us to read this data. Nature hasn’t made life easy for us. Thus, a significant part of the analytical work we do at the paleomagnetic lab is investigating the magnetic properties of the archaeological materials. Fortunately, in this particular study, Yoav was able to decipher nature’s magnetic code and give us important information from several angles – historic, archeological and geomagnetic.”

“To reveal the magnetic field, we need sources of information from well-anchored points in history. We very rarely have a historical event like the destruction of Jerusalem that occurred thousands of years ago that we can date so accurately — down to the year, month and even day,” Vaknin concluded. “It’s important to understand that despite disputes about the overall historical validity of the [Hebrew Bible], the description of the events that occurred in the Kingdom of Judea during its last 100 years was written almost in real time, and the biblical text is generally considered reliable for this period. The destruction of the First Temple is corroborated by numerous archaeological findings from the Land of Israel in general and Jerusalem in particular, such as royal storage jars with rosette stamped handles and seals and seal impressions with names mentioned in the biblical text.”