Venusian evolutionary histories and connections to present day observables

ABSTRACT

Despite Venus & Earth having distinct atmospheres and surface temperatures, they have similar densities and sizes. They may also likely have similar bulk compositions, making comparison between them extremely valuable for illuminating their distinct climate histories and their exoplanetary cousins. We use presently available data on Venus alongside knowledge about Earth's climate history to support a number of different evolutionary hypotheses. Evaluating several snapshots in time over the past 4+ billion years, we show that Venus may have sustained liquid water and moderate temperatures for much of this period. Cloud feedbacks from a slowly rotating world with surface liquid water reservoirs are keys to keeping the planet clement. Yet how could Venus go from habitable to hot-house? Our results demonstrate that it was not the gradual warming of the sun over the eons that contributed to Venus’ present hot-house state. Rather we hypothesize that large scale volcanism and the observed global resurfacing could have played key roles in ending the clement period in its history and aligning our models with its present day atmosphere. I will also touch on connections to upcoming Venus missions and exoplanetary observations that can test our hypotheses.