Cosmic Queries – Life on Other Planets with Aomawa Shields

Astrophysicist and astrobiologist Aomawa Shields spends her workdays asking a deceptively simple question: of the nearly six thousand exoplanets discovered so far, which ones might actually be habitable? Her research team starts after the planets are found, using climate models originally designed to forecast Earth’s own warming to simulate what conditions might be like on distant worlds. The stakes are high: among those thousands of confirmed planets, only a tiny fraction have the right conditions for liquid water — and that fraction may shrink or grow depending on the type of star they orbit.

What makes a planet habitable (and why we might be biased)

Shields is explicit that the search for life elsewhere is fundamentally Earth-centered. “We’re looking for earth-like planets around sun-like stars,” she says. “You can’t get more sort of biased than that.” The definition of habitability she and most astrobiologists use requires three ingredients: a liquid (on Earth, water), an energy source (sunlight or chemical energy from deep-sea vents), and the basic organic building blocks like carbon, sulfur, phosphorus, and nitrogen. These are the conditions life as we know it needs — but there are astrobiologists whose job is to ask what life as we don’t know it might use instead.