We asked seven researchers what drives the hunt for planets outside our solar system — and got some surprising answers:

Jessie Christiansen, research scientist, NASA’s Exoplanet Science Institute:

“I search for exoplanets because I love the feeling of discovery — finding something new that no one has ever seen before! In particular I like discovering exoplanets because the planets in our solar system are so substantial and tangible to us that I can then imagine what exoplanets around other stars might look like.”

---

Matthew W. Smith, systems engineer, NASA’s Jet Propulsion Laboratory:

“I search for exoplanets because I want to know whether there’s another Earth-like world out there, and whether life could exist outside our solar system. I think about these questions every time I’m in a dark spot looking up at the night sky.”

---

Sara Seager, astrophysicist, planetary scientist and exoplanet researcher at the Massachusetts Institute of Technology:

“I search for exoplanets for the journey of exploration. It’s incredibly exciting to come across a planet that is different or new and exciting — even in some small way — from planets known before.”

---

Padi Boyd, project scientist for NASA’s TESS mission (Transiting Exoplanet Survey Satellite):

I search for exoplanets because I think one of the most profound and thought-provoking questions humanity has ever asked is, “Are we alone in the universe?” Philosophers and curious humans have been asking this question for thousands of years, but we are the first generation who have the tools at our fingertips to begin to answer this question with scientific observations. Not only do we now know of thousands of planets around other stars, and not only can we infer the existence of hundreds of billions more, but we are finding a dazzling array of planets, some very different from the ones in our own solar system. In a way, each new planetary system we discover teaches us a little bit more about how the universe works, and how the Earth, Sun and own planetary system fit into the whole.”

---

Jessie Dotson, project scientist, NASA Ames Research Center:

“There are so many reasons to search for exoplanets. But the core reason for me is that I’ve always wanted to know how things are made. (And really I mean how everything is made — bread, buildings, chocolate, roads, stars, planets, galaxies…I was the kid with the endless stream of annoying questions!) In graduate school I studied star formation regions. I’m now fascinated by how planetary systems (both our own and others) are formed. There are plenty of solid theories on how planetary systems form, but ­we’re in a really exciting time now, when we’re finding enough systems at enough different ages that we’re starting to really test those theories. So, I search for exoplanets because I want to know how they were made.”

---

Karl Stapelfeldt, chief scientist for NASA’s Exoplanet Exploration Program:

“People in many cultures can relate to the idea of a planet: They live on one, in Earth’s Moon they directly see another world, and from a young age they learn the names of the other planets in our solar system. More than nebulae, galaxies or even other stars, planets around other stars readily fit into our shared cultural understanding of the universe. Exoplanet exploration bridges the heavens into human consciousness, and that’s why we do it.”

---

Mary Voytek, senior scientist and director of NASA’s Astrobiology Program:

“I don’t do (direct) exoplanet research, but I happen to understand it well. We spent all of our research time before we knew about exoplanets understanding our own solar system — how the planets formed. Observing exoplanets allows us to determine whether or not we actually understand those processes, even in our own solar system. In fact, what we’ve seen so far is that most stellar systems don’t look like our solar system. What finding exoplanets does for us is open up a vast exploration area to look for other habitable worlds. And it has upped the likelihood that we are not alone.”