Why you should care

Sara Seager is 100% confident that her quest to find extraterrestrial life will succeed. Thanks to her research, vast outer space is starting to feel within humanity’s grasp again.

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The first time Sara Seager crashed a star party she was hooked. As a child, gathering with other amateur astronomers to observe the night sky and peering at the moon through a telescope with her dad was “spectacular.” It wasn’t until she was 16 that she realized she could actually study stars. When she proudly announced her ambition to become an astrophysicist to her dad, he yelled at her for two hours straight. He urged her to choose a stable career as a doctor or lawyer.

I know it’s out there. It’s like a snowball, and you can’t stop it now.


But Seager, 42, rejected familiar career paths and entered an astronomy doctorate program at Harvard. At a time when scientists scoffed at the idea of studying planets beyond our solar system — known as exoplanets — she wrote her Ph.D. thesis on the topic. She went on to build a comprehensive theoretical framework for detecting these far-off planets, helping to transform exoplanet discovery into a respected field of study. Now, the MIT professor and widowed mother of two is on a quest for the field’s holy grail: an exoplanet just like Earth that also harbors life. And she’s 100 percent confident we’ll find it.

“I know it’s out there. It’s like a snowball, and you can’t stop it now,” she said. “Statistically speaking, it’s bound to happen, and it’s starting to be corroborated.” Last week, Seager testified before the U.S. House Science Committee that scientists now have the technology to discover extraterrestrial life.

Planets lined around an orange sun in space

Artwork of a hypothetical planetary system around a sun-like star. The planetary system includes rocky and gaseous planets in tight orbits.

Source Corbis

What would it mean to find an Earth twin in the outer reaches of space? After all, using current propulsion methods, it would take a spacecraft thousands of years to reach even our nearest star, making a mission to this theoretical Earth twin impossible for several more years. Still, finding an Earth twin that also harbors life could have a profound psychological effect. “It will be a humbling, transformational experience,” Seager wrote. Finding an Earth-like planet would make outer space seem less vast, and complete the West’s centuries-old conceptual shift away from placing humanity at the center of the universe. It’s the kind of shift could revitalize space exploration.

Not long after Seager arrived at Harvard in 1995, reports of exoplanets orbiting stars similar to our sun were beginning to emerge. These planets were as big as Jupiter, but located so close to their suns that a year — the amount of time they took to orbit the sun — was only four days long. But some scientists were skeptical. They attributed the periodic dimming of these sun-like stars to their ability to swell and shrink, for example, not to ”hot Jupiter planets” passing in front of them.

Finding an Earth twin that also harbors life could have a profound psychological effect.

Undaunted, Seager decided to model the atmosphere of these planets for her Ph.D. project. Even her thesis committee thought she was crazy. What if scientists ultimately concluded that the new planets weren’t planets after all?

Seager ignored them, partly because she wasn’t committed to becoming a scientist; she just loved studying exoplanets. Plus, she would still graduate, even if the data ultimately disproved her model. “I had nothing to lose. I really didn’t care what anyone thought,” she said. “It was new and risky and just sounded awesome.” Nicknamed the “astronomical Indiana Jones,” Seager is also a risk-taker outside of her research who loves whitewater canoeing and wilderness skiing.

After earning her Ph.D. in 1999, Seager headed to the Institute for Advanced Study in New Jersey to continue studying exoplanets with astronomer John Bahcall. Unlike other scientists, Bahcall supported Seager’s research with “unbounded enthusiasm,” she said. “He said if you have a great idea and you have the physics to back it up… you should go for it in a big way.”

In Bahcall’s lab, Seager developed a method for finding and studying exoplanet atmospheres, which led to the first detection of an exoplanet atmosphere in 2002. The ability to characterize an exoplanet’s atmosphere is crucial for determining whether it could support life. Biological processes generate oxygen, carbon dioxide and other gases that make up Earth’s atmosphere. That means an exoplanet with a similar atmosphere might also harbor life. Seager’s technique laid the groundwork for a whole new field. “She literally wrote the book on exoplanet atmospheres,” said Yale University astronomy professor Debra Fischer.

At least one will be the right distance from its star and heated to the right temperature so that it has water on its surface.


In 2007, Seager became an assistant professor at MIT, where she has continued to pioneer methods for identifying exoplanets, especially those that resemble Earth. One of her projects is to determine what types and amounts of gases could indicate the presence of life on exoplanets. She’s also led efforts to design Starshade, a space telescope with a shade to block bright starlight so that astronomers can better spot small, Earth-sized planets and confirm whether they harbor life. She’s expected to become the mission’s chief scientist when it launches.

Seager is “absolutely confident” scientists will find an Earth twin, although when that will happen depends on funding. Kepler and other space telescopes have already detected so many Earth-sized planets orbiting sun-like stars that “at least one will be the right distance from its star and heated to the right temperature so that it has water on its surface,” she said.

It’s that fearless optimism that makes Seager “a pioneer in her field,” said Fischer. “You make only incremental advances if you follow the path other people have taken. The thing that characterizes her work is the boldness and the vision. She sees completely fresh, new directions.”

That same tenacity helped Seager push through tragedy in 2011, when her husband died of cancer. “I worked nonstop on astrobiology,” she said. “It was the only thing that brought me joy, besides my kids.” The months after her husband’s death were the most creative and productive of Seager’s life; she published 13 scientific papers in 2012 alone. The experience gave her a newfound sense of clarity that helps her juggle research with raising two sons, aged eight and six.

It also arms her against the doubt she still faces from other scientists. Now that more than 1,000 exoplanets have been discovered, her peers are less skeptical about her scientific ideas and more skeptical that she’ll get enough funding to finally launch Starshade. As usual, Seager isn’t fazed. “I’m going to do everything in power to make that happen,” she said. We’ll wish on that star.


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