Over 4000 planets have been discovered around stars other than Sol; and statistics suggest that the number of planets in the galaxy is similar to the number of stars. In the coming decades, we will begin to possess the tools and data needed to characterize terrestrial exoplanets. We want to apply our knowledge of Planet Earth’s system to those of exoplanets; but there is a huge gap in the quality and quantity available data. To bridge that gap, it is vital to study the interacting systems of terrestrial planets in our own Solar System. Venus is the planet in our Solar System closest in size to Earth, and is our heliocentric neighbor. A hundred or so years ago, it was thought that Venus was “another Earth,” albeit perhaps a bit warmer and maybe also more humid. However, we know today that the surface of Venus is hot enough to flash bake a pizza, and the surface pressure is comparable to having a bus park on your hand. How did Venus and Earth come to be so disparate? Is the inhospitability of Venus unusual; if so, what went wrong at Venus? Is the lush habitability of Earth unusual; if so, what went right at Earth? Are both Venus and Earth typical end states of terrestrial planet evolution? In order to answer these questions, we need to greatly advance our understanding of how the Venus system works.
Not only is Venus a sort of Rosetta Stone for comprehending the exoplanetary zoo, but the clouds of Venus hold the key to deciphering the workings of the coupled systems of Planet Venus. The clouds reflect three-quarters of the sunlight incident at the planet; and species among the clouds absorb about half of what remains. The clouds are also a primary extinctor of the magnitude of near infrared emitted radiance; consequently, they are a primary source of data for assessing the dynamics of the venusian troposphere, but also a primary complicating factor for radiative transfer. In this talk, I will summarize a bit of the work to understand the nature of the clouds of Venus that has guided my career, and lay out a road map for what I feel should come next.