Geophysicists have probed deep into Earth’s childhood and recorded the earliest measurement yet of the magnetic field that protects the planet from devastation by the solar wind. The finding provides new insight into Earth’s early years and could even reveal more about when life began. The history of Earth’s geomagnetic field plays a key role in scientists‘ understanding of the development of our planet’s deep interior, its atmosphere, and even the early evolution of terrestrial life. But scientists have had a hard time pinning down how long ago the magnetosphere first formed. Now, geophysicist John Tarduno at the University of Rochester in New York, and colleagues, have made the earliest direct measurement of Earth’s magnetic field. They discovered that the magnetosphere was already in existence 3.2 billion years ago, 500 million years earlier than previously believed. The researchers extracted minimally disturbed bits of feldspar and quartz from 3.2 billion-year-old rocks in the Archaean Kaapvaal craton in South Africa.
Abstract (PDF): Rory D. Cottrell, John A. Tarduno and Michael K. Watkeys
„Examining the strength of Earth’s early magnetic field“