This Scientist Combs Our Universe To Find Life Among The Stars


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‘One morning in January — it was a clear, cold morning; I shall never forget that morning — as I was taking my usual walk along the (mill) race . . . my eye was caught with the glimpse of something shining in the bottom of the ditch. . . . I reached my hand down and picked it up; it made my heart thump, for I was certain it was gold.”

-James Wilson Marshall, whose discovery of gold in 1848 was the catalyst for the California gold rush.

When astrophysicist Sara Seager first began looking for another life-sustaining “earth” in the early 2000s, hardly anyone was studying in the field of exoplanets (planets beyond our solar system). In fact, scientists had only recently confirmed that they existed at all.

“The field was so wide open,” she says. “Honestly, it was the gold rush.”

Like the gold rush of the mid 19th century, the field was about to become incredibly competitive. Being the very first to find an exoplanet that is like our own, one that could potentially support life, has turned the space race into an outright sprint. Because for scientists like Sara Seager, finding that particular exoplanet would be just like being the first person to strike gold in California in 1848. It wouldn’t just change her life, it would change everything.

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Seager vividly remembers the moment the lightbulb went on that illuminated her path to becoming a world renowned scientist.

“I was in high school and we were studying physics,” she says. “We had this assignment where the teacher was holding a big wooden board with a big hole in it. And we had a spring.” The goal, she explains, was to shoot the spring so that it would make an arc through the hole from across the room. “We actually had to work out an equation that we’d been learning about. Then you had to set your angle based on your distance. No intuition, just with these equations. Mine made it through the hole.”

As Seager recounts this memory, you can still hear the pride in her voice.

“It was just a thrill,” she continues. “Because it hadn’t occurred to me that you could write an equation down that could predict how something will behave.”

That was the moment she fell in love with physics. Partially, because it brought order to the mysteries around her. With one equation she discovered that she could predict and understand the world better. And she loved that.

Before long, Seager wasn’t satisfied just bringing order to our world. She wanted to use physics to bring order to the whole universe. She would look up at the stars and wonder what they were, what was really out there.

“I was always intrigued by all of that,” she says. “I just got really lucky because I somehow learned you can put those together, the equations, to understand the stars.”

From there, Seager was sucked into the field of exoplanets, an obsession that would determine the course of her entire adulthood. She’s devoted her career to looking for a life-supporting exoplanet like ours, and she’s not going to stop until she finds one.


Simply put, an exoplanet is a planet that orbits a star outside our solar system. It seems obvious now that they exist. Haven’t we always known that there were other planets out there? But the truth is that while people had theorized, imagined, and fictionally created such worlds for a very long time, scientists weren’t able to actually confirm the existence of an exoplanet until 1992. And when they did confirm them, they were completely shocked by what they found.

Let’s back up even further: For a very long time, scientists had assumed that another solar system would operate much like our own. Which made sense. Until then, they only had our own earth to go off of when creating theories and equations. But when they actually found what they’d been looking for, they discovered Jupiter-like planets 20 times closer to their sun than our Earth is to ours. That may not sound crazy to a lay person, but in the field of planetary sciences, it was pretty rattling.

“It was almost sacrilegious,” Seager says. “It was just not allowed to have a planet like Jupiter literally 10 times closer to a star than Mercury is to our sun. It’s so close. What is it doing there? How did it form there?” So instead of confirming that there were many solar systems out in the Universe that operated similarly to ours, the discovery did the opposite. It taught us that our solar system was actually rare, and it upended the field of planetary science entirely.

This moment in time — just as planetary science was about to make a seismic shift — was when Seager was entering the field, a time when a new frontier was opening.

“When I was in graduate school, getting my PhD, that’s when these exoplanets were first discovered,” she says. “It was really amazing.”

Her story seems to echo the Malcolm Gladwell book, Outliers. It’s filled with tales of people who just happened to be in exactly the right place at the exactly right time to find themselves at the forefront of their fields. It proposes that Bill Gates wouldn’t be Bill Gates if he hadn’t had rare access to a computer growing up right at the time computer science was about to explode.

When asked how timing has affected her own course, Seager pauses to consider the possibility.

“It’s partially that,” she says thoughtfully. “But don’t forget it’s also about taking the risk. Other people, when presented with the same opportunity, may not take it.”

Seager may have been lucky that exoplanets were being discovered right as she started her career in planetary science, but as for her entering the field and dominating it, she deserves the credit that’s been heaped on her. For many at the time, the idea of undertaking a search for exoplanets, even the concept of studying their atmospheres seemed like it would be virtually impossible. Had Seager not seized the opportunity, and decided to face the risk of jumping into a brand new field, she wouldn’t be in the place she is today.

So where is she today? She’s a MacArthur Fellow and was tenured at MIT by 35. She was named one of Time Magazine’s 25 Most Influential in Space in 2012 and she leads a team at NASA. In short, Seager is seriously important in her field. But when asked what she believes her biggest accomplishments have been, she’s hesitant to brag.

“I always feel like my best accomplishments are in the future,” she says. “That’s what keeps me going. The future’s always better.”

The future may just prove this bold proclamation correct, because Seager hasn’t just been searching for exoplanets, she’s actually been a critical part of designing how we study them. She was the first to lay out the specific technique that we use to observe exoplanet atmospheres — by analyzing the way light and color pass through (like shining a flashlight through fog). Thanks to her innovations, scientists can now actually tell what gasses are in evidence, a topic most scientists didn’t even know how to approach.

Now that scientists can determine the makeup of exoplanet atmospheres, the exciting part happens. They look for a planet with the right conditions to support life. Seager has more than one project involving the study of these gasses, and is on a quest to find a combination that might lead us to a planet like our own.

Which, she muses, might be exactly what an intelligent species on another planet could be doing while looking at us.

“On our own planet we have oxygen which we need to breathe,” she explains. “Yet, it’s highly reactive and should not be in the atmosphere at all. So, if there are intelligent aliens orbiting a nearby star that have the kind of space telescopes that we’re trying to build, they’ll definitely be scratching their heads over this! If they know how to build a space telescope to see oxygen, they’ll understand basic chemistry, and they’ll know that we shouldn’t have oxygen. They’ll say, is it created by life or is it created by some other possibility? They’ll be thinking really hard about what it could be.”

Wondering about the potential aliens and other life forms that could be out in the universe is part of what drives Seager, part of why she says people seem to care about the discoveries she’s trying to make. Movies like Arrival tap into a question that humanity has struggled with for a very long time.

“We just want to know our context, our place in the universe,” Seager says. “Why are we here? Are there others like us? I think trying to answer that set of questions is what the discovery of a life-sustaining exoplanet would mean. It’s the first step to answering the question, are we alone? Is there other life out there?”

In conversation, Seager oscillates between tempering expectations of what we might actually find in our lifetimes and feeling thrilled about this amazing era in scientific study. When asked how it feels to look in the stars for a planet we could most likely never go to, she’s unwilling to toss out the possibility of interplanetary travel so quickly. If there is life on the planets around some of the very nearest stars, she wouldn’t rule out us being able to reach them sometime in the future.

“Five years ago, ten years ago, no one would legitimately say that it’s within our abilities to do that,” she says. “But now people are really talking about it.”

That’s the long-term goal, in the short(er)-term what we’re looking for now is a way to find confirmation of another life sustaining atmosphere. Though even that won’t offer the confirmation that scientists are looking for.

“We’ll have signs of life, “ Seager explains. “But it’s like, imagine we’re walking through the forest, and you see some smoke. Is that from a fire or from something else? It’s sort of like putting all the pieces of the puzzle together.”

In many ways, this is what Seager’s job is. She’s putting together a puzzle without the helpful aid of the big picture on the front of the box. She has to imagine what the final design might be. Still, she searches for the patterns undaunted — seeking clues and doing her best to fit it all together. When pieces do slide into place, she finds herself amazed. What once seemed impossible has become possible, over the course of a few decades.

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The Trappist-1 system located 39.5 light years away is the latest discovery of exoplanets. Some could potentially sustain life.


Ultimately, Seager hopes she will be part of the discovery of another Earth.

“If we see oxygen on another planet, and we can spot another couple of gasses, that would be thrilling,” she says. “That will be literally the pinnacle of my whole life. And then I can retire.”

Of course, whether or not Seager is serious that she would retire if she finally found another potential earth, is yet to be seen. But it seems unlikely, because that discovery would only lead to a thousand more questions, a million more possibilities. Could one of the brightest scientific minds of our lifetimes walk away from something like that, just when things are starting to get good? Doubtful.

When pressed, Seager admits that spotting a planet with oxygen in its atmosphere and a star like our own sun, would be incredible, but that it “would only be the first step. It would be a whole new universe in a way.”

And who wouldn’t want to see that?

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