Dr. Seager explains how she and other astronomers are looking for extraterrestrial life. We discuss the Drake and Seager equations. We also talk about how astronomers might be able to detect life by measuring chemicals in distant planet atmospheres.

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Using a model, MIT astrophysicist Sara Seager demonstrates Starshade, under development at NASA’s Jet Propulsion Lab in Pasadena, California. Deployed in space, the device, more than 100 feet in diameter, would block the light from a star. A space telescope would capture an image of a planet when it’s between Starshade’s petals, seeking evidence that life may exist on the planet.

(PHOTOGRAPH BY SPENCER LOWELL / NATIONAL GEOGRAPHIC)