The case for Venus

The search for life elsewhere in our universe is exploding. Discoveries of new exoplanets are now a weekly occurrence. Our curiosity about exoplanets is motivated by the tantalizing possibility that we might discover another world where life as we know it could thrive.

Traditional conceptions of the so-called habitable zone for terrestrial bodies assume that within our solar system, only Earth is in the sweet spot for life to form and survive. But that presumption overlooks the temporal variation of habitability: Both Venus and Mars likely had liquid water as far back as 3.6 billion years ago (see figure 1). In fact, exoplanets may even be more Venus-like than Earth-like. Recent research suggests that the number of exo-Venuses is comparable to, or even exceeds, the number of exo-Earths.