Skip to Content
wgbh News


The Search For Another Earth Is Happening Right In Our Backyard


Science is, by nature, precise, tedious and incremental. And yet, I’ve never met a scientist whose work was not animated by the search for answers to big question. And for astronomers, there’s no bigger question than, “Are we alone in the Universe?” 

"Finding life in the universe is not going to be a single eureka moment like you saw in the movie, Contact," said says Kelly Beatty, senior editor for Sky + Telescope magazine in Cambridge.

Instead, said Beatty, it will be a series of iterative steps. Steps like the invention of the telescope hundreds of years ago, and steps like the one that was announced by NASA on Wednesday.

"We are excited to announce...there are actually seven Earth-sized planets orbiting the nearby TRAPPIST-1 star, about 40 light years away," said Thomas Zurbuchen, Head of NASA Science Mission Directorate, at a press conference at NASA headquarters in Washington, DC.

"What's more, three of these planets are in the habitable zone, where liquid water can pool on the surface," he continued.

Seven Earth-sized planets orbiting TRAPPIST-1, at least some of them rocky, three in the so-called 'Goldilocks Zone,' where the temperature is just right for liquid water.

To be clear, we’ve already discovered thousands of exoplanets, some of them even Earth-sized, but Beatty says this discovery is particularly exciting.  

"What makes this system special is that it’s close enough that we can someday hope to study each of these seven planets individually, and it’s really got a lot of attention."     

Attention because one – or more – of these planets could be harboring life. Still, it's a long way from here to there. There is still plenty that we don’t know about the planets in this TRAPPIST-1 solar system.

"We don’t know if there’s water on them. We don’t know if they have atmospheres yet."

Answering that question will fall to people like astrophysicist Sara Seager, a professor of planetary science and physics at MIT, who invented a technique for studying exoplanet atmospheres that has become the industry standard.

Keep in mind that when Seager entered the exoplanet field some 20 years ago, it was largely derided by other scientists as an idle hobby, like stamp collecting.  

"I was applying for faculty jobs at top universities around our nation, and I was rejected from being hired because people thought the field of exoplanets wasn’t really going to go anywhere," she said.

They could not have been more wrong. In the last decade, the exoplanet field has completely taken off.

"Young astronomers are funneling into the field of exoplanets," said Seager. 

At MIT, she is among dozens of scientists honing the tools and techniques for not only discovering new planets, but scanning them for signs of life. One of those scientists, Julien de Wit, a Postdoctoral Associate, participated in the TRAPPIST-1 discovery. 

MIT is also leading a NASA Mission set for launch next year called TESS (Transiting Exoplanet Survey Satellite) that will look for more even planets around distant stars. 

Another partner in that mission is just across town: The Harvard-Smithsonian Center for Astrophysics. There, some 40 to 50 scientists are focused specifically on exoplanets, including astrophysicist and Harvard professor David Charbonneau.

"It has turned out to be such an incredibly rich field," he said. "One of our projects is called the MEarth Observatory, and so we’re looking for Earth-like planets around very small stars. I have another team that’s very interested in trying to improve the ways we can study the atmospheres of planets."

And it will be the makeup of the TRAPPIST-1 planets' potential atmospheres that will reveal whether any of these Earth sized planets are really Earth like planets.

"The first thing we’re going to look for is water vapor in the atmosphere," Seager explained. "On a small rocky world that indicates a liquid water ocean. And all life as we know it needs liquid water. If there’s water, we want to look and see if there are gasses that don’t belong that might be produced by life."

As you might imagine, analyzing these planets from such a great distance is a difficult proposition, and our current technology only allows us to see – and extrapolate – so much. But a big boost comes next year when NASA’s new James Webb Space telescope launches, a tool that Seagal believes will help provide some real answers.

"I’d say, a couple of years from now, we’ll know a lot more about the planets in the system."

In the meantime, the search for other planets – and life on them – will continue right in our backyard. Something that Charbonneau marvels was considered little more than science fiction just a few decades ago.

"We all want to be part of something really big," he said. "That’s what carries you through all the hard years in grad school, it's what carries you through going night after night after night to some mountaintop to get some data. So I think that it’s great that we’re able to openly ask the question, 'Are we alone?' and realize that’s something we can aspire to answer on a time scale perhaps as short as 10 years."

And if life is eventually found, around TRAPPIST-1 or anywhere else, it will be a giant leap for mankind, made possible by countless small steps.

WGBH News coverage is a resource provided by member-supported public radio. We can’t do it without you.