Natalie Batalha is one of the brilliant astronomers leading NASA’s wildly successful Kepler planet-finding experiment. Her team has announced a string of remarkable discoveries in recent months, including the discovery of Earth-sized worlds and planets, like Tatooine, around binary stars.

So when Rice University astronomer David Alexander told me Natalie was visiting Houston I jumped on his offer to interview her. Here, then, is a largely complete transcript of our 45-minute conversation.

You spend your life now studying planets around other stars. Were you interested in astronomy as a kid?

It’s kind of an atypical case. Most of my colleagues knew they wanted to do astronomy from a young age. That wasn’t my upbringing. Neither of my parents went to college, and I didn’t understand what it meant to be a scientist at all. But I always excelled in math. And in the background, growing up in the ‘80s, the shuttle program was going on and that was an exciting time. It seemed to me that the most exciting job that anyone could have would be to work for NASA and support the space program. How many of us thought that, right? We all did.

But I was also very influenced by other people’s perceptions of me. Those of my parents, for example. We see our strengths and weaknesses reflected through their eyes. Science was not being reflected through their eyes. And also my high school, the Richmond Unified School District in California, had minimal resources. They didn’t have a strong science program. I was at the top of my class, so I got recruited to Berkeley, and I went with the plan of studying business or doing something like that. When you’re young, you just don’t know. I just started taking a lot of different classes and decided to try physics. My idea was to bridge business and science, maybe. But when I took physics everything changed. It was addicting, it opened my mind.

What was the attraction, the way that you could use science to understand how nature worked?

For me it was much more profound than that. For the public the only way to explain it was as a religious experience, although it wasn’t religious in terms of creator and all that kind of stuff. It was a view of the universe, and my place in the universe. On a profound level it allowed me to see that ordinary events could be explained with mathematics. I hadn’t been exposed to this before. Holy cow, even the rainbow on that puddle with the oil on top of it, that can be explained with math. That blew me away. The universe, to me, no longer appeared as a collection of chaotic events, but as something ordered. And if it’s ordered, and we can write down math to explain it, the idea that there might not be any limit to that knowledge is enticing. Maybe human beings have the potential to really understand the big questions, and why we’re here.

Well, you lived your dream. How did you find your way to NASA?

Things snowballed. As an undergraduate I ended up applying for an internship one summer (at the at the Wyoming Infrared Observatory), never thinking I would get it. There’s a theme in my life that I think is common to a lot of females in science, which is always to underestimate ourselves, downplay our skills and to have low expectations. That may be an exaggeration, but I thought I wouldn’t have a chance. But I got it and I got exposed to the scientific method for the firs time. I got to see and discover things that I knew no one had ever seen before. What a thrill. At the end of the summer the professor there suggested I contact Gibor Basri, a professor at UC Berkeley, who worked in a similar field. I did and he hired me as an undergraduate researcher. He’s been a collaborator for my whole life. He now works on the Kepler mission.

Even then, while I was doing this work and enjoying it, I didn’t think I could get a Ph.D. But I went ahead and applied and UC Santa Cruz accepted me. It’s one of the top schools in astrophysics. So I went and I remember sitting there looking at the other students, thinking I can’t compete with them. There’s no way. It’s all a farce. I don’t belong here. I think it’s normal to feel those kinds of things when we push ourselves and go outside our comfort zones.

Half the people in the room were probably thinking the same thing.

Exactly. That’s right. So that’s been the great lesson. Especially at NASA, and having to go through the struggles we did to get that mission flying. Kepler was rejected four times before it was ever selected. It gives you perspective.

When did you first get involved with the Kepler mission?

In 2000. So it’s been 12 years now. It hadn’t been selected yet for funding. We were writing the proposals.

How many people were involved with it?

Four others. The core scientists were Bill Borucki, David Koch, myself, Doug Caldwell and John Jenkins.

By then several exoplanets had already been found, right?

The first exoplanet was found in 1995. I was graduate student at the time. I was studying stellar physics at the time, and exoplanets were discovered by observing the stars. You have to understand the stars in order to find the planets. And so me and lot of other people now studying exoplanets started out in stellar astrophysics.

In 2000, why was Kepler not getting selected?

It kept getting rejected for different reasons. I remember reading about Kepler before I joined the team. One of the reasons why I was skeptical is because stars have spots, like our Sun has sunspots. And the spots rotate in and out of view. They’re exactly the size of a planet. My expertise was in spots, the magnetic features on stars like our Sun, but younger. So I just started thinking about it and I sent Bill Borucki an e-mail. I said, “You know, this is really interesting what you’re doing, but I’m just really skeptical because of these spots.” It was fortuitous because one of the reasons why the previous proposal had been rejected was because someone was skeptical because of stellar activity. He invited me to NASA Ames discuss it more, and within three months I was there working. I helped rewrite the part of the proposal that spoke to that issue.

How did you address the issue?

Stars that are young have a fast spin, so their spots are moving more quickly, and therefore the variations in light from the star will be shorter and the up and down, up and down starts to compress on a timescale of a planetary transit event. So for example, for a planet like our Earth going around a star like our sun, at one astronomical unit, the duration of a transit’s dimming of a star’s light is about 12 hours. So for our own Sun, which has a spin period of a month, 12 hours is nothing. Spots don’t change on a 12-hour timescale. But if you have a star that’s rapidly rotating they do and so that’s where it becomes confusing. So the task at hand was to figure out what percentage of the stars we would see would be in that category, and it’s like 20 or 25 percent. We’re observing 155,000 stars, so we don’t care about the 25 percent. We accounted for it. If 25 percent of stars have this problem, we just observed 25 percent more stars.

Back then, when you got involved, what was the thinking about what you would find with Kepler?

No planets had yet been discovered by the transit method. The first one came in 2001. Up until that time no one even believed it would work. People were very skeptical. The other lucky thing that happened, just as we had submitted this new round of proposals for Kepler, the first transiting exoplanet was discovered by another team. That was a team lead by David Charbonneau and Tim Brown. That planet wasn’t first discovered by the transit technique, it was discovered by the Doppler technique. But it also happened to be an edge-on system (star HD 209458), so they knew where to look and they found it using the transit method. That was a great help to us.

When did Kepler get selected for funding?

It was December of 2001. We didn’t launch until 2009. So there were seven years of development to plan, to decide what stars to observe. It was a lot of work.

Have you been surprised, a decade later, by the instrument’s discovery of thousands of planets around other stars?

It’s exceeded our expectations. Looking at the first data was like breaking open a piñata and finding candy everywhere. And every time we’d look at a star and find evidence of a planet, we’d collect a little more data and there was another signature of a planet in the same light curve of the same star. It’s kind of a joke. We kind of laugh. Every time we collect more data we find more planets. It means these systems are very flat, even more flat than our solar system. And these multiple systems, we just did not expect to find so many of them. It’s giving us an incredible amount of dynamic information about how these systems form.

What has this told us about planetary systems that we did not know?

With these systems you can really study the dynamics. For example there’s this phrase where we say a system is “dynamically packed.” What that means is the planets are as packed as they can be without being so close that a system becomes unstable, planets perturb one another and start being ejected. They’re just at that limit where they are as dynamically packed as they can be without things going haywire. And our own solar system in essence is kind of like that. You’ve got lots of planets but they’ve got stability. That seems to be a theme in nature. What this means is that planets are going to be very common. Lots of stars are going to have planets, and many of them.

The other thing we’ve learned is that it’s possible for planets to orbit more than one star. Binary stars are very common in the universe. Half of the pinpoints of light you see in the sky are probably binaries, two stars not one. Planets exist around those kinds of stars too. Kepler 16 was an example, the Tatooine world. A couple more of these systems were just announced in January.

How has Kepler changed our perception of our galaxy?

The other day, this just happened a week ago, I was out for a run and it was nighttime. When I came back the sky was especially clear. At the end I looked up at the sky, as I always do. But something fundamentally changed when I looked up at the sky. Instead of seeing just the pinpoints of light, all of a sudden, I looked up and didn’t see stars but planetary systems, thinking to myself they were everywhere. It may sound like a trivial thing, but for me it was a huge thing. Kepler has changed the way we see the galaxy.

How long will Kepler keep flying?

We have enough consumables to last for another 10 years, but the costs have to be balanced against other science programs. What Kepler was designed to do was identify the fraction of stars in our galaxy that have Earth-sized planets. What we really want is the fraction of stars in our galaxy that have Earth-sized planets in the habitable zone. To answer that question we need more time to find more cases of planets of that type. It takes more time to find planets further out from their stars, because there’s more time between transits. So with four years of data we expect to be able to figure out the number of stars with Earth sized planets in the habitable zone. We’ve got a lot of work to do to get that. Probably at least four more years.

The NASA science community has made a lot of sacrifices, most recently in its Mars exploration program to pay for the James Webb Space Telescope. How does the community feel about Webb?

The astronomical community has made tremendous sacrifices over many years now to make the James Webb Space Telescope a reality. We do that happily because we know its potential to do great things. But it’s hard to do that because many of our careers have seen sacrifices in what we would like to see done. But we do it knowing Webb’s potential. With that said it’s hard to see it struggle, it’s hard to see the overruns because that means another year of tightening our belt. But it’s going to be a fantastic instrument.

My last question is by far the most important. Is Pluto a planet?

Ohh gosh. It’s a dwarf planet.

But the International Astronomical Union specifically said dwarf planets are not planets.

I go along with that. I’m fine with that. I don’t have any special attachment to Pluto as a planet. But it still belongs to an important class of objects, right?