The Goldilocks Planet? How Silicate Weathering Maintains Earth “Just Right”

Abstract

Earth has been continuously inhabited throughout most of its history, starting from at least 3.5 Ga (Catling and Kasting 2017). Part of the evidence for life’s antiquity comes from stromatolites, the remains of photosynthetic, mat-forming organisms. These early photosynthesizers probably did not produce O2; however, like modern cyanobacteria and algae, they required surface (or near surface) liquid-water environments. But surface liquid water is not present on other planets within our solar system, and it might not have been present on Earth, either, had our planet not been endowed with a mechanism for stabilizing its climate. Here, I review how that mechanism works on Earth and what it might mean for the possibility of finding Earth-like planets, and life, around other nearby stars.