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Cascade Falls, Virginia, Earth (left) and Venera 13 landing site, Venus (right). Both examples of landscapes of planets in the habitable zone within our solar system.
Sept. 28, 2023

Earth and Venus: Twins, Yes but, Probably not Separated at Birth

Venus is often referred to as Earth’s twin. While they are similar in size and bulk composition, the surfaces of these twins could not be more different. Earth is a temperate world where liquid water is stable at surface and Venus has a surface temperature similar to the self-cleaning mode of an oven. From the perspective of a global geoscientist, the most striking difference is that Earth has plate tectonics while Venus does not. However, on closer inspection, there is abundant evidence that the surface of Venus has changed through time. I exploit a previously-overlooked observation—the small (~300 m) difference between the center of mass and center of figure of Venus—to show that a popular explanation for the youthful surface would cause Venus to wobble in analogous fashion to a tire out of balance. The same geodynamic calculations explain another puzzle—the formation and distribution of coronae. Coronae are circular ring fractures that sometimes have uplifted central domes; they have no known Earth analogue. Using machine learning, we look for clusters in the surface distribution of coronae and find a connection between coronae and the deep mantle. These observations indicate that Venus has cooled and evolved quite differently from Earth for the past 10% of solar system history. Going back further in time becomes increasingly challenging.

Earth and Venus: Twins, Yes but, Probably not Separated at Birth
Host: Julian Lowman
Event series  Physics Colloquium