Planet Gazer

Sara Seager studies worlds beyond our solar system.

As a child, Sara Seager was convinced that the moon followed her wherever she went. The thrill of peering at it through a telescope when she was five is one of her earliest memories.

Sara Seager Credit: Mark Ostow

As Seager was getting that first good look at the moon in 1976, astronomers at NASA were already discussing the need for a space-based infrared telescope. When the Spitzer Space Telescope launched into orbit nearly three decades later, Seager herself would be one of the scientists using it to study the atmospheres of planets beyond our solar system--planets that no one was sure existed 10 years earlier.

By 1995, the moon had followed Seager to grad school at Harvard, where she was choosing a PhD thesis topic. That fall, Swiss scientists announced they had spotted a planet orbiting a star in the constellation Pegasus--the first of what would soon be several planets detected outside our solar system. Seager wrote her thesis on how the atmospheres of "hot Jupiters"--extrasolar planets that are giant and gaseous, like Jupiter, but much closer to their stars and thus more than 10 times hotter--are affected by radiation from their stars. Today, she's considered a pioneer in the study of extrasolar planets, or exoplanets. "In some fields you just make incremental progress toward questions that have been there for decades," she says. "In this field, we come up with as many questions as answers."

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With more than 200 exoplanets now documented, researchers are understandably enthusiastic about having so much new territory to explore and explain. "People are excited, and they just want to do new things but often aren't as careful as they should be," says Seager. "It's like the Wild West. Things happen so fast, you just do things. Then you leave." Eager to bring more sophistication to the field, she joined the MIT faculty in January to launch a new program in extrasolar planets and is developing an exoplanet course she'll teach in the fall. "I came here to bring some of the knowledge and tools [of MIT atmospheric science] into exoplanet atmosphere research," she says. As the Ellen Swallow Richards Associate Professor in the Department of Earth, Atmospheric, and Planetary Sciences, Seager now rubs shoulders with meteorologists and atmospheric scientists as well as fellow astronomers. Topographical maps of the United States and the world frame the doorway of her Green Building office, where she ponders planets well beyond our solar system.

Seager's "lab" consists of her brain and her computer, which is stocked with data collected above Earth's atmosphere by the Spitzer telescope. Her office contains little else. Boxes of files from her last job, as a senior researcher at the Carnegie Institution of Washington, line one wall; unpacking them would take time away from her research. A blackboard hangs on another, covered with diagrams illustrating techniques she and others developed to glean clues about exoplanets' atmospheres.