Planetary shield formed soon enough to protect early life forms from harmful solar radiation
Evidence for the existence of Earth’s magnetic field has been pushed back about 250 million years, new research suggests. The field may therefore be old enough to have shielded some of the planet's earliest life from the sun’s most harmful cosmic radiation.
Earth’s magnetic field was born by 3.45 billion years ago, a team including researchers from the University of Rochester in New York and the University of KwaZulu-Natal in South Africa report in the March 5 issue of Science.
That date falls during life’s earliest stages of developme