John Valley, a professor of geoscience at the University of Wisconsin-Madison, agreed that the conditions for life could have existed on Earth so long ago. Valley wasn’t involved in the new research but was among the first scientists to use zircons to show that Earth had ancient oceans and cooler temperatures more than 4 billion years ago, challenging the view that Hadean Earth was a hellish orb with fiery seas of magma.
Office of Strategic Communication