Fossilized Raindrop Dimples Add to Mystery of Ancient Earth’s Warmth
Pumice-like cratery indents formed by ancient raindrop splats are adding to the mystery of why the adolescent Earth was warm enough to host rivers and oceans, despite the dim sun of the day. Thanks to fossilized impressions from rains that fell down on Africa 2.7 billion years ago, the “Faint Young Sun” paradox is getting curiouser and curiouser.
During the late Archean era, around 2.7 to 2.5 billion years ago, the sun was roughly 20 percent dimmer than it is now. This lower solar radiation should have encased the Earth in ice, but geologic evidence is to the contrary, suggesting that either greenhouse gases, a different atmospheric pressure or both kept things warm. The physics of raindrops can help answer the question.