KATHLEEN DAVIS: This is Science Friday. I’m Kathleen Davis.

SWAPNA KRISHNA: And I’m Swapna Krishna one thing I’ve always done is to look at the stars for clarity, understanding, and inspiration. It’s really where my deep-seated love of space comes from, and it’s a lot of the reason I have the career I do today, reporting on and talking about exciting space news. And I’m not the only one who feels this way.

In her recent memoir, astronomer and astrobiologist Dr. Aomawa Shields describes her search for signs of life in the cosmos and, in parallel, her quest to build a meaningful life here on Earth. She charts her life story from childhood to astronomy to acting and back to science and what she’s learned along the way. She joins me now. Dr. Aomawa Shields, professor at UC Irvine, and author of Life on Other Planets– a Memoir of Finding My Place in the Universe. She’s based in Irvine, California. Welcome to Science Friday.

AOMAWA SHIELDS: Thank you. I’m so thrilled to be here.

SWAPNA KRISHNA: Let’s start at the beginning. Where did your fascination with outer space come from?

AOMAWA SHIELDS: Well, ever since I can remember, I was that person who was looking up at the sky. I would run into telephone poles on the street as a little girl because I was looking up. And I remember, as a child, going to these air shows for the Blue Angels aerial flight team, and that got me to thinking more about what’s up there. And so I started to look up at night, and see all these stars, and keep asking those questions.

What’s up there? How far does space go? And eventually, are we alone in the universe?

SWAPNA KRISHNA: From very early on, you felt torn, really, between two things, that you love very much acting and science. And then you toggled and went kind of went back and forth between the two. Can you describe that journey for us?

AOMAWA SHIELDS: So my journey is anything but linear. I started off devoted to space and astronomy. And when I was 12, I saw this movie called Space Camp about kids who get launched into space accidentally, and I was like, that’s what I want to do. I want to be an astronaut.

And I am a planner. So I plotted my career. And at age 12, I was going to be an astronaut, get a degree in astronomy. And then I ended up stumbling into an audition in high school for a play.

And so all of a sudden, I had these two loves, astronomy and acting. And it wasn’t until I got to college when it became clear that it was important to choose one thing. I started in astronomy, then waffled over to acting because the astronomy route got a little bumpy. And I did acting.

And then that didn’t feel like it was fully me. And the book is really this journey of acceptance of both of those parts of myself and that maybe it was important for me to choose for a while. But I knew that both of those things needed to be a part of my life for me to feel fully whole. And that’s really the ultimate message that there really is no one way to live a life.

SWAPNA KRISHNA: After years of acting, you went back to school to get your PhD and one thing you said in your book that really struck me was you were thinking about how you were going to be 40 by the time you were done with your PhD. And you kind of said to yourself, well, I’m going to turn 40 anyway. I might as well do it with a PhD.

I think that’s such a cool way to think about it. It’s never really occurred to me. I’m going to be that age anyway, might as well get the thing I want to get along the way. What was it like to go back to school after all those years away?

AOMAWA SHIELDS: Oh, my gosh. It was hard, in one word, hard, and at the same time, in a different way, simple. And what I mean by that is the first time around I started this PhD program at, first, right out of undergrad, and that, did one year. And then I switched to acting. And during that one year, I was incredibly divided. And there was so much going on in my head.

The second time around, over a decade later, when I came back at the age of 34, I knew exactly what I wanted to do. But it was hard because a lot of the obstacles were internal obstacles. There were messages that I was telling myself about who I was as an older African-American astronomy graduate student in a field that was predominantly white and predominantly, where my cohort, they were all much younger than me.

SWAPNA KRISHNA: One of the things I love about your book– and there are many things I love about your book– you always have a space analogy for the feelings you write about. In space terms, is there a way you would describe that feeling of going back to school?

AOMAWA SHIELDS: The Big Bang.

[LAUGHTER]

And think I also described later in life, much, much later, a few years ago, getting tenure at my institution. Also it’s like these big moments of really fully feeling all of the molecules in my body almost individually. Whenever I have that moment, it feels like the Big Bang, which is that the beginning of the universe, when it’s just like everything is an explosion of light, and matter, and heat, and energy. And that’s how it felt.

SWAPNA KRISHNA: I want to talk about your research a little bit. You ask a huge question, both in the book and in your field of study. And it’s one we’re all dying to know the answer to– are we alone in this universe? How do you even go about answering that?

AOMAWA SHIELDS: Well, there are many ways to answer this question. And the way that I answer this question and my team answers this question is, once a planet is found, what we can do is use computer climate models to figure out just how habitable this planet really is. So finding a planet that orbits its star at a particular distance, which we call the habitable zone or the Goldilocks zone, where the planet could be warm enough for liquid water, that’s step 1.

But just because a planet is in the habitable zone doesn’t mean that it is habitable. And there’s so much that we can’t yet know from observations. And so that’s where our work really comes in is that we can fill in the gaps between what’s known observationally and what we need to know to be able to answer the question, is this a planet that could support liquid water on the surface? Which is our overwhelming criterion for whether life might be able to support itself or survive there.

It can’t be the only criterion. But it’s our prevailing criterion because we know every single life form, from the tiniest microbe to the largest elephant, requires liquid water on this planet. So that’s the guiding criterion that we use. And so we can look at, with climate models, the very same models that have been used to predict climate and weather patterns on the Earth, we can change the host star from the Sun to some other star.

We can change the composition of the atmosphere from an Earth-like atmosphere to a different type of atmosphere and figure out what kind of atmosphere this planet that’s been discovered would need to have to be able to support liquid water on the surface. And we can change so many more things about that planet to really tell observers, OK, this is a planet that we think you should highlight as the most likely to succeed in the habitability category to follow up on with next-generation instrumentation.

SWAPNA KRISHNA: And are there any planets that you and your team are looking at specifically that look promising in our galactic neighborhood that could maybe support life?

AOMAWA SHIELDS: Well, for a while, we’ve been particularly interested in a system called TRAPPIST-1. And TRAPPIST-1 is the name of the star, and it hosts seven planets, all of which are Earth sized. And that’s really exciting because we’ve seen, through statistics and observational work, that, if a planet is about Earth size to about one and a half times the size of the Earth, it’s probably going to be rocky. And if it’s rocky, then oceans could sit on top of it. And if there’s oceans, there’s probably life.

And so that regime of planets that are about the size of the Earth are most likely to be rocky or terrestrial planets. And TRAPPIST-1 having seven of them has been really exciting. And about two or three of them orbit in the habitable zone of their host star. We took a stab at trying a range of different land surface compositions that are possible on these planets, and we were able to identify some of these planets that could be habitable for a given land surface composition.

And we uncovered that TRAPPIST-1d, for example, would be able to have above-freezing surface temperatures for water if the surface composition is something that’s very low reflectivity, like a granite type of surface. And we’re doing some really exciting things with planets that we don’t even know exist yet, but we think actually proven that they could exist. And that’s even more fun for me is being able to say, is there a situation on a planet that could exist? And could that situation be stable climatically?

SWAPNA KRISHNA: So personally, do you hope there’s life out there? And if so, do you think we will find it?

AOMAWA SHIELDS: I personally hope and have a personal belief that there is life out there. Now, that belief is not based in any kind of evidentiary information. I’ve been thinking about that movie, Contact, that talks about– there’s a line that, if it is just us, it would be an awful waste of space. There’s 100 billion stars– over 100 billion stars in our galaxy alone, and there’s hundreds of billions of galaxies in the observable universe.

We’ve only scratched the tiniest part of a surface. And so we have so much more out there to look for. Through sheer numbers alone, in my mind, it’s unlikely that it’s only us. And what I’m excited about is allowing more people to be involved in this endeavor than have ever been involved in any kind of space or scientific endeavor thus far.

We saw the Apollo Moon Landings. If you look at what the mission control looked like back then in the ’60s, it was very homogeneous, in terms of both race and gender. Now, think about what would happen if we had this mandate of, we are going to answer this question, are we alone in the universe? And I think we’re closer to answering that question than we’ve ever been before.

Now, if we were to allow people from all walks of life, all races, all genders, and including young middle school girls, like the girls that I involve in my program, Rising Star Girls, who, yes, are still on their academic journey but are being taught to have a personal connection to space and the universe, this idea that only certain kinds of people can be and should be involved in this endeavor is an old one. And it’s outdated now.

And I think that really the key to being able to answer this question within our lifetime or certainly our children’s lifetime is expansion, expansion of thought, expansion of ideas, expansion of old beliefs about who can be involved in that quest. And the more expansive we get about that endeavor, the more likely we are to be able to answer that question.

SWAPNA KRISHNA: And you mentioned your program Rising Star Girls. And it blends the arts and sciences together. And what power do you think comes out of that combination?

AOMAWA SHIELDS: First of all, science is an incredibly creative endeavor. You have to be creative to think of questions about the universe and even more creative to figure out how you’re going to address those questions. And there’s a lot of different ways to do that.

And also the arts, we’ve seen in the literature that when we incorporate, for example, literary and role-playing exercises into the study of astronomy, it actually increases these girls’ confidence in both asking and answering questions in the classroom. So we’ve used the evidence-based literature as a platform to create this program, where we are not only teaching middle school girls of color what a star and a planet is and a galaxy and a constellation is, they’re also filtering that knowledge through their own personal lives.

So they’re writing poems about the universe, about that star, that galaxy and also about themselves intertwined with that knowledge. And the hope is that, once the heavier math comes in as they progress in their academic education, they’ll be less likely to abandon their love and interest in astronomy because they will have that personal connection between the universe and themselves.

SWAPNA KRISHNA: This is Science Friday from WNYC Studios. You also write that slowing down and embracing stillness creates room for your mind to wander, which you made the connection earlier that you need that creativity to ask questions in science. So what do you think of as stillness? What does that mean to you? And is there anything that you have discovered or has come to you scientifically because of stillness?

AOMAWA SHIELDS: I’m developing a deeper and deeper relationship with stillness now in my life. In academia, there’s a lot of rewards for being productive and being driven and ambitious. And the reality is that there may not be as many rewards on paper for the choices that I’ve made to be still, to, for example, lay down for 20 minutes using a guided meditation. Or when I do make time for that, I find these incredible ideas come to me, either ideas about my personal life or ideas about my professional life.

That idea about the terminator-habitable planet– if you had a planet that has a permanent day side, that where it’s like super, super hot on that day side, and a permanent night side, where it’s super, super cold on that side, and it’s not habitable on either side, could you have a region of habitability in the middle along the dividing line, which is we call the terminator? And could that climate state be stable?

And we were able to show that, in fact, it could. And we call these planets terminator-habitable planets, which, of course, makes me think of the Terminator movies. But I’m pretty sure that came to me not when I was typing away on a computer or even sitting in someone else’s science talk. It was just relaxing and thinking about what I hadn’t learned from current research, what hadn’t been discussed at conferences. And I can’t do that if I’m doing other things. I have to get still to find those questions. I have to have those questions rise up into my awareness.

SWAPNA KRISHNA: Before we go, your memoir is about discovering yourself alongside understanding the mysteries of the universe. Do you find that looking at the cosmos helps you understand yourself better?

AOMAWA SHIELDS: It does. It’s why the first quote that I give at the beginning of the book is a poem by a Japanese poet Izumi Shikibu, and it’s, watching the Moon at dawn, solitary, mid-sky. I knew myself completely, no part left out.

I look up at the Moon or the stars in the night sky. It’s this understanding that, no, I’m not alone. No, not any of us is alone. And whether that means there there’s other life out there or there’s just other things out there, other phenomena, other planets, other stars, none of us is alone.

And that is very comforting to me because it allows me to have a greater, more broader perspective on my life, my individual problems and concerns, and truly, at the same, time to be aware of how precious I am and each one of us is. So it’s like, as I discuss in the book, there’s room for all of everyone’s hopes and everyone’s dreams. And if there’s something that you’ve been wanting to do for your whole life that you haven’t done yet, what are you waiting for?

SWAPNA KRISHNA: Dr. Shields, thank you so much for joining me.

AOMAWA SHIELDS: Thank you.

SWAPNA KRISHNA: Dr. Aomawa Shields is an astronomer and astrobiologist at UC Irvine and author of Life on Other Planets. To read an excerpt from her book, go to sciencefriday.com/otherplanets.