earth

Earth’s magnetic field existed about 250 million years earlier than previously thought, new research suggests, which would make it old enough to have shielded life on the planet’s surface from the sun’s most harmful cosmic radiation. Earth’s magnetic field was born 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 formation date falls during life’s earliest stages of development, between the period when the Earth was pummeled by interplanetary debris and when the atmosphere filled with oxygen. Several earlier studies had suggested that a magnetic field is a necessary shield against deadly solar radiation that can strip away a planet’s atmosphere, evaporate water and snuff out life on its surface. so the earth is a hero...