New Study Shows Earth's Magnetic Field is as Strong as it was 3.7 Billion Years Ago

Thursday - April 25 2024, 08:15 UTC - 7 months ago

A new study has found that Earth's magnetic field was just as strong 3.7 billion years ago as it is today. This magnetic field was crucial for protecting life on Earth by shielding against harmful cosmic and solar radiation. The ancient magnetic field strength was comparable to today's strength and provides insight into the formation of Earth's solid inner core and the evolution of our planet.

A new study published in the Journal of Geophysical Research has uncovered a 3.7-billion-year-old record of Earth's magnetic field. The study, conducted by researchers from the University of Oxford and MIT, found that the ancient magnetic field was as strong as today's magnetic field, crucial for protecting life on Earth.

Earth's magnetic field is responsible for shielding us from harmful cosmic and solar radiation, such as the charged particles emitted by the Sun. Without this protection, life on Earth would not be possible. However, scientists have not been able to determine when the modern magnetic field was first established, until now.

The researchers examined iron-containing rocks from Isua, Greenland, which act as tiny magnets that can record magnetic field strength and direction during the crystallization process. They found that rocks dating back 3.7 billion years captured a magnetic field strength of at least 15 microtesla, which is comparable to today's magnetic field strength of 30 microtesla.

This discovery provides the oldest estimate of the strength of Earth's magnetic field derived from whole rock samples, which is more accurate and reliable than previous studies that only used individual crystals. Lead researcher Professor Claire Nichols of the University of Oxford emphasized the significance of these results, stating, "Extracting reliable records from rocks this old is extremely challenging, and it was really exciting to see primary magnetic signals begin to emerge when we analyzed these samples in the lab. This is a really important step forward as we try and determine the role of the ancient magnetic field when life on Earth was first emerging." .

One interesting finding from the study is that while the magnetic field strength has remained relatively constant over time, the solar wind - the stream of charged particles from the Sun - has been much stronger in the past. This suggests that the protection of Earth's surface from the solar wind has increased over time, making it possible for life to thrive on land and move out of the oceans.

Earth's magnetic field is generated by the mixing of molten iron in the fluid outer core, propelled by buoyancy forces as the inner core solidifies. However, during Earth's early formation, the solid inner core had not yet formed, raising questions about how the early magnetic field was sustained. These new findings suggest that the mechanism driving Earth's early dynamo was similarly efficient to the solidification process that generates Earth's magnetic field today.

Additionally, understanding how Earth's magnetic field strength has changed over time is key for determining when the inner, solid core started to form. This information is crucial for understanding the rate of heat escape from Earth's interior, and can provide insight into processes such as plate tectonics and the evolution of our planet.