The Earth’s magnetic field is one of the most mysterious and underexplained physical phenomena on our planet. While it’s understood that the magnetic field is the result of Earth’s spinning metal core and this field helps shield Earth from solar and cosmic radiation, the behavior of this geomagnetic field sometimes eludes scientific explanation. The magnetic field occasionally reverses polarity with seemingly random frequency, and unexplained cracks have been observed to appear in the magnetosphere. Geological evidence indicates that other types of geomagnetic anomalies have been quite common throughout history.
Case in point: researchers from Tel Aviv University, Hebrew University of Jerusalem, and University of California San Diego recently announced their analysis of an unexplained magnetic spike occurring roughly three thousand years ago. During this spike, the strength of the magnetic field shot to its highest observed level in the past 100,000 years.
According to their publication, the extent to which this anomaly affected the planet, and how, is still a mystery:
Our new data support the existence of an interval of extremely high field intensity during the late eighth century BCE [...] the exact geographic expanse of this phenomenon has yet to be investigated, and the fact that these are very short-lived features that can be easily missed suggests that there is much more to discover.
The data in this study were gathered from the handles of sixty-seven ceramic jars made in the ancient kingdom of Judah, lands which today comprise much of southern Israel and parts of Jordan. Each jar handle was stamped with the royal seal of local rulers, making them an accurate way to date these pottery shards. Because ceramics such as this pottery contain metallic elements which can 'record' certain markers about the magnetic field, they are excellent sources of data for archaeomagnetic study.
The researchers believe that this study could open up new methods for dating other artifacts whose dates are unknown. With a more thorough magnetic record, which this study helps complete, the magnetic evidence left in any undated ceramics or clay samples could become an accurate method for dating.