Prior studies have hypothesized that some polluted white dwarfs record continent-like granitic crust—which is abundant on Earth and perhaps uniquely indicative of plate tectonics. But these inferences derive from only a few elements, none of which…
Combining occurrence rates of rocky exoplanets about sun-like stars, with the number of such stars that occupy possibly hospitable regions of the Milky Way, we estimate that at least 1.4 × 108 near-Earth-sized planets occupy habitable orbits about…