EAS Spring 2018 Seminar Series Presents: Dr. Giada Arney, NASA Goddard

Identifying habitable and inhabited exoplanets will be a major and exciting challenge in coming decades. Modern Earth provides a useful starting point for discussions of how to characterize other habitable planets, but Earth’s long habitable history provides many examples of other kinds of habitable worlds dominated by different biospheres and environmental conditions.

These other faces of Earth can be used to broaden our understanding of how to remotely detect life and habitability on exoplanets. In particular, during the Archean geological eon, Earth may have occasionally hosted a global organic haze, similar to the haze in Titan’s atmosphere. This biologically-produced haze would have dramatically impacted Earth’s habitability and remotely observable properties.

Hazy Archean Earth is one of the most “alien” worlds we have geochemical data for, so it is valuable in the context of identifying alien signs of habitability on exoplanets. Here, we explore this “pale orange dot” to gain a more complete understanding of what a very different Earth-like world can be like, and to anticipate the opportunities and challenges of observing such worlds as exoplanets.