Here’s a climate puzzle — one that goes back to Earth’s infancy some 4.5 billion to 2.5 billion years ago. The sun was much dimmer back then. Far less solar radiation reached the planet. Earth should have been a frozen wasteland. But all geologic signs point to a young planet awash in liquid water, with the first life-forms emerging.
Log in
Subscribers, enter your e-mail address for full access to the Science News archives and digital editions.