Scientists discover rocks that provide earliest evidence of Earth's magnetosphere

Scientists discover rocks that provide earliest evidence of Earth's magnetosphere
27 Apr 2024

A groundbreaking study led by University of Oxford geologist Claire Nichols, has uncovered evidence of Earth's magnetic field in 3.7-billion-year-old rocks from Isua, Greenland.

These ancient stones contain remnants of the planet's magnetosphere, strikingly similar to the invisible structure that continues to protect our planet today.

This exciting discovery offers the earliest look at our planet's magnetosphere, and can help scientists unravel the factors that led to the emergence of life and the evolution of Earth's atmosphere.

Magnetic field strength is similar to today
Magnetic consistency

The research team examined iron in ancient rocks from the Supracrustal Belt, an area shielded from tectonic activity for billions of years.

They found that the magnetic field strength 3.7 billion years ago was at least 15 microtesla, surprisingly close to today's strength of around 30 microtesla.

This indicates that the early geodynamo, responsible for generating Earth's magnetic field, was as effective and efficient as it is today.

Increased protection from solar wind over time
Life's shield

During the Archean period, the Sun was more active, and the solar wind was stronger.

The study suggests that Earth's magnetic field has provided increasing protection over time, possibly playing a role in the emergence of life.

The researchers believe that life may not have appeared until the magnetic field's protection reached a certain level.

Implications for Earth's atmosphere evolution
Insights

These findings could also shed light on the evolution of Earth's atmosphere, as there is evidence that a significant amount of ionized xenon and hydrogen were lost during the Archean period.

A slightly weaker magnetic field could have allowed for more exposure to solar winds at the poles.

Further research is needed to determine how magnetic field behaved and changed from Archean onward, but it's now certain that Earth has maintained an intrinsic magnetic field since 3.7 billion years ago.