The sun spews energetic particles that can pry life-sustaining molecules from our atmosphere, but Earth’s magnetic shield, which originates from the planet’s hot core of churning, liquid iron, shoos those particles away. Scientists disagree, though, about how long our magnetic field has been around, keeping the planet habitable. Until recently, the best guess was that Earth’s magnetic armor was 3.45 billion years old. Now, in Science Smackdown, we look at two recent arguments on whether current evidence points to it being even older.
The Magnetic Field Is Very, Very Old
A research team led by John Tarduno of the University of Rochester in New York went to Australia’s Jack Hills and collected ancient samples of rock containing the crystallized mineral zircon. Once zircon cools below a certain temperature, roughly 1,085…