NASA's Curious Universe - Webb's Exoplanet Research Sounds Like Sci-Fi—But It's Real

Episode Date: September 3, 2025

Some exoplanets—like a gas giant with rain made of glass and 5,000-mile-per-hour winds—sound like worlds dreamed up by a science fiction writer. But they’re real. From light-years away, scientists can uncover details about planets orbiting distant stars and even ask whether some exoplanets could support life. Néstor Espinoza, an astronomer at the Space Telescope Science Institute, explains how NASA’s James Webb Space Telescope is revealing new details about exoplanets, especially rocky worlds like Earth.

You're listening to NASA's Curious Universe. I'm your host, Jacob Pinter. Imagine a movie that starts like this. The camera pans up and we see a spaceship. It's sailing toward an alien planet. The planet is cobalt blue and it's gigantic, bigger than any planet in our own solar system. It even has water vapor.

But the explorers in the skyline, the spaceship know they have to be careful because this planet's atmosphere is basically blow-torched with the rain of molten glass whipping in winds of more than 5,000 miles an hour. So the spaceship keeps flying. And as the movie continues, we see other bizarre worlds. There's a planet that orbits a small red star. It's unknown if the planet has life. But if it does, it does, That red starlight could make plants here red or purple, even black. We also glimpse a rogue planet. Somehow this one broke free from its star.

It roams the galaxy alone and in perpetual darkness, never to see another sunrise. Well, here's the big plot twist. All of these planets are real. Hollywood didn't make them up. They're called exoplanets. A whole assortment of planets beyond our solar system orbiting faraway stars. If you go outside and you just speak a random star, chances are that star has a planet orbiting around it. Nestor Espinoza is an astronomer at the Space Telescope Science Institute.

If they have rocky planets, do the atmospheres look like, you know, the Earth or Mars or Venus or something else completely? We have no idea. We just started exploring them. It sounded science fiction up to five years ago. Now it's science. It's not science fiction anymore. She's pretty fun. Now, these exoplanets are too far away for our spacecraft to visit. But we have tools to study them, including the James Webb Space Telescope.

Webb is a huge telescope in space a million miles from Earth, studying the cosmos in ways that we just can't from Earth's surface. NASA leads the international partnership that built Webb, and the Space Telescope Science Institute handles its science and operations for NASA. That means Nestor was there in Webb's first moments, watching engineers take Webb for a test drive. Nestor planned to use Webb's data

to prove whether exoplanet science was something he could really do with this mission, and almost instantly he got his answer from the universe. Like I got that answer within like 15 minutes, It was like a complete yes, and I already knew it was going to be beyond what we were expecting. Like the signal was just so much better. Like nothing I have ever seen. From that moment, I knew like this is going to make everyone crazy.

But getting that cosmic yes was only the beginning. Before it launched, scientists around the world knew what Webb was supposed to be able to do. Now they were waiting to hear how it really performed. Nestor sifted through the data, making sure Webb could capture as much detail as the world hoped. Doing Exoplanet science with James Webb, it's not that straightforward. Typically, you know, you want to look at a star with James Webb. Point at a star, you get like your data and that's it. With Explanet data, you have to massage the data a little bit more in order to extract the signals that you want because they're very tiny signals.

So what makes exoplanet data so tricky? Imagine traveling far, far away from our own solar system and trying to look back at Earth. From out here, the sun is a speck, just one of many. As we try to zoom in on the sun, we run into a problem. It's really bright, so much brighter than Earth. There's just no hope of seeing the faint glow of our own home planet. But there is a way we can detect it. Whenever a planet passes in front of the sun, the sun would appear just a little bit dimmer.

And since planets radiate their own energy, when they disappear behind the sun, we could detect that too. That tiny bit of information may not sound like much. But with careful study, scientists can use it to figure out details like a planet's temperature and what chemicals are in its atmosphere. Since the first discovery of an exoplanet in the 1990s, scientists can use it to figure Scientists have cataloged thousands of these planets all across our galaxy. Some of them are exotic worlds in classifications like hot Jupiters or sub-Neptune gas giants. Nestor's research focuses on rocky planets, like Earth.

And if you're thinking what I'm thinking, the next step is to ask, could these rocky planets also show signs of life? Now, rocky planets are smaller, and that makes them harder to study. NASA is already planning for a future telescope called the Habitable Worlds Observatory, specifically designed to hunt for signs of life. In the meantime, Nestor says Webb is giving us a lot to work with. It's a big universe out there and there's a lot of stuff to study. What made you say this is the thing that I want to spend my life looking at? So from when I was a kid, I think everyone has gone through the stage in which you're kind of obsessed with aliens, right?

either from movies or like E.T. and stuff like that. Or Star Wars, for instance. A big fan of Star Wars. I remember I think that's when started. My mom brought me to these, for some reason, they redid the original Star Wars movies, episodes, you know, 4th through 6, and they put it in the movies.

And my mom had only one free day in her week. She worked a lot. We were basically just my mom and I. She had one day free in the week, and she said, We're going to spend the whole day and we're going to see the three episodes. I was like 11. Back to back to back.

It was nuts. I was like, I have no idea what this movie is about. Well, I'll just go. And it blew my mind too, right? This thing of seeing like tattooing with two sons. I guess, what? This thing could exist out there. You know, planets that are covering ice, planets that are like or Earth or desert planets.

And that was nuts. So that really kick started the thing, like that little seat. Yeah. And that just grew. I never thought I could actually be a scientist. So I come from Chile. And in Chile, I don't know, from science is not like a, it was not a thing that I knew one could do. From TV, I thought, you know, there's scientists out there, but it's done by folks at NASA and other places.

But I'm like very far away from that. So at some point, my physics teacher just grabbed me and she told me like, you know, I've seen you, you know, with this broad. bright eyes in physics and you like this astronomy thing a lot. You know you can be a scientist, right? This was like, was 15. And I was like, but you really, you can get paid for like doing science? Like for like discovering new things. Like that sounded completely nuts.

It's like someone paying you to play video games, right? Right. And she was like, yeah, that's a career and you can study it here. So that was like kind of the path to science in me and the path to exoplanets. Physics teachers, moms. Star Wars. So I wonder if you can fill in the blank in this sentence for me. James Webb is teaching us blank about exoplanets.

There's no single word really because it's revolutionizing the field, really. We are starting to see maybe the first hints of evidences of atmospheres around rocky exoplanets. That was well beyond our capabilities three years ago, you know, before the launch of James Webb. This is really the next frontier. Like if we want to get and eventually detect life out there, the first question is, does this rocky planet have an atmosphere or not? And we can see that in our solar system even. So, you know, Mercury has like a very thin, almost non-existent atmosphere.

Right now that's because it's just too close to the sun, right? Poor planet. Sure. Maybe it had an atmosphere. It's getting baked all the time. Exactly, yeah, poor planet. You can bake a pizza in the thing if you want. But then it doesn't have like a substantial asthma for your atmosphere.

you know, the one we have on Earth, the one that Venus have. And stars out there are also very different. They, you know, we're used to these beautiful sun that we see every day. But there are stars of all sizes and colors out there. And in fact, one of the things that impresses the public, I think, the most, is when you ask them, what do you think is the average star out there? How does it look like? And everyone tells you like, ah, you know, it's like the sun.

And the answer is no. It's not like the sun. It's actually a star that is like, you know, kind of 10% the size of the sun. So much smaller. That makes it much rather. And then you have to be closer to that star in order to feel the same heat because it's smaller. It's colder. Right.

Just like a heater. So those stars really outnumber all the rest of the stars. Those are the majority of the stars out there. So we also know that rocky planets, actually most of the rocky planets live around these small stars. We're trying to explore how does the average rocky planet out there looks like, which orbits these small stars, which is very alien. Like if you imagine the sky on these things, it's completely different. Like you are used to this orange star coming up.

Like imagine now like a very small star coming up. It's red, like very, very red. So if there's like plants or something like that on these rocks and these planets, they might look completely different. They might observe completely different light. They might look completely different. So figuring out these alien worlds, it's this exciting thing that James Webb is allowing us to do. The thing that the James Webb Space Telescope, I think, is the most famous for is that it is looking back to cosmic dawn and sort of the very first galaxies and so on.

And in a lot of ways, that's what it was designed to do. So what makes those tools that it has also really useful for studying exoplanets? That's an excellent question. So what you do is that you wait until the planet passes in front of the star from your point of view at Earth. And with the planet passes, if you're lucky enough to see that passage, some of the starlight passes through the atmosphere of the planet and interacts with it. And those little signals are the ones that we detect with James Webb and we're able to extract like some sort of like cosmic detective bark, right, which see which light got absorbed by the atmosphere of the planet. What we're trying to do is see which part of that starlight is being eaten up by the molecules in the atmosphere. And different molecules like to eat different colors of light.

They have like different diets. So if you want to detect sodium, for instance, you know, your classic, you know, salt. You typically go to what we call optical waveings, which is light that we can see. Like you and I can see, like the color of your shirt, the color of your pants. That's light, colors of light that we can see. But there's many other colors out there. In particular, James Webb is what we call an infrared telescope. So it's able to detect light, which is called infrared light.

It's passed, like way rather than the reddest you could see, that we cannot see. Our eyes just can't detect that. In the infrared, it's exactly where the molecules that were most excited about, like, you know, water, carbon dioxide, which is like a big thing on the rocket planets on the solar system, methane. all of these molecules, their diets of light, are based on infrared light. So if you want to detect those molecules, you have to go to the infrared, right? And that's what makes James Webb so unique. You have this big bucket of light that is very stable,

and it's able to look at exactly the colors of light on which these very important molecules are absorbing. Do you think you could take me on a little tour of some of the exoplanets you study? I don't know, can we pretend that we're visiting and can you tell me what we see and what it even might be like to actually go there and be on the surface or be in that atmosphere or something? Totally. Yeah, I can do that.

So right now we don't have solid detections, but I can make a case for this. And I think I'm going to put as an example case. One planetary system that is very dear to my heart because I've been working a lot on that And it's called the Trappies One system. So in order to travel to the Trapeas One system, we have to take a rocket and travel like several tens,

like a couple tens of light years. That means that if we threw like a little laser, it will take like 20 to 30 years to get there. So the first alien thing about the system is that the star is crazy small. The star is the size of Jupiter. Okay. She's like, what?

Like, a star can be that small? The answer is, yes. They can be that small. And this system doesn't have, you know, one, two, or three, four rocky exoplanets going around. It has seven rocky exoplanets going around these stars. The other alien thing about the system is that all these planets orbit very tightly packed together. So they are in orbits. there are in an orbit that it's smaller

on the orbit of Mercury. All these seven planets, they're all packed in an orbit that is very, very small. The other alien part about this Trappisman system, I told you, is seven planets. Two or three of those planets are in what we call the habitable zone of this system, which is a distance from its star

in which is not too hot and not too cold such that if they had atmospheres like we have on Earth, they could sustain liquid water in their surfaces. And that's pretty exciting because it means, you know, maybe life is there. Even more, because the system is still tightly packed. If we, you know, we were traveling to this thing, if we were to go and land on one of these planets and you looked up in the sky, you could actually see the other planets as like big moons.

So if you have a friend in this other habitable planet, you know, the other one, you can call them and say, hey, there's a storm coming your way. like three hours, right? Which is nuts, right? The fact that it's so packed means that you can see the planets in the sky, the other planets in the sky. So that would be, you know, a beautiful sight. Even better than Tatooine, right? Even better, right?

So that's the whole thing with this field. It's like you think you have seen cool stuff in science fiction? Wait until you see the science data, right? That's crazy. This is maybe going to ask you to take your scientist hat off and put your scientist's your prediction had on, but do you think that we'll find signs of life on an exoplanet, I don't know, within your lifetime? I surely hope so.

Science, yes. I think we would be able within my lifetime, especially with what we have lined up in the future. So will we be able to detect these biosignatures within my lifetime between 30 years, 40 years from now? I think the answer is probably yes. will we be able to claim unambiguously that that aliens like walking on the planet? Probably not.

But that's where our scientific community gets together to try to figure out what alternative scenarios will produce this particular signal. And I'm very confident that we will get to very good answers with that. Like the scientific community, once it focuses on a problem, it's very good at figuring out how to make that happen.

You just mentioned, for instance, that the James Webb Space Telescope was made basically for, like, you know, the deep universe, trying to figure out the first galaxies and so on. So they really thought very hard on how to make that with James Webb. That is the beauty of the habitable worlds of serveries. The first time in history of humankind that we're saying, we're going to build a big mission, big telescope. And this is going to be based on trying to figure out this, you know, actually get the signatures of possibilities of life out there in other planets. And that's a very exciting, again, it's a very exciting time to be alive, to be in this era in which we are jumping and to try to figure out if there's life out there.

It's like it's never happened before. It's amazing. I was thinking about when you said that you grew up and didn't know that being a scientist was an option. What advice do you have for someone who, is interested in science, but also may not realize that that is a real career path. Yeah. So what I would say, well, first of all, that it is a real career. It's a thing you can do. So first thing is that there's not a linear career path.

You don't have to be like a total genius that gets into physics, top grades, and then you go and do amazing discoveries. That's just not how it works for the majority of us. If you have an interest and an excitement for this, that is like 60, 70% of the way. That is if you're really excited about this stuff, then this is a career path for you. It's not going to be easy. Like, I can tell you that from the very beginning, but it's going to be totally worth it. I would also say that, and this is sometimes underlooked, that, yes, your excitement and for the science and so is really important,

but also having a support system is really important. I told you that basically it was my mom and I, and that support for my mom and for my friends and so on was key for me to going through this. I mean, if it weren't for them, I would not be here. The final advice that I have for people that want to do science is that I know people have this concept of scientists being like these white-coated folks that are just in their own labs in the whiteboard, right,

and they're alone, lone wolves. I've seen it in the movies. Right, eureka, I solved, you know, cancer, whatever. That's not how science works. Science is a very, very collaborative environment. Like, my native language is Spanish. So I have to learn how to speak English and how to communicate effectively and so on. That is also very important.

If you're hearing all of this and you say, wow, you have to do a lot of stuff, you can't do it. If you're excited about this stuff, you can't. can be that scientist. I have one last question for you, and then we'll get you out of here. Since our show is called Curious Universe, what are you still curious about? Well, I'm curious about these atmospheres around rocky planets. And in particular, if the atmospheres survived around the Trapeze 1, Exoplanes. If they did, and we find a system that it's in the habitable zone of their stars,

that has an atmosphere that we can characterize in detail, that would be such an amazing moment in humanity. Like, yes, we have this chance to figure out if life might be in this planet. That is the thing that has to me the most curious. And the overreaching kind of bigger question to that is how frequent this life out there? The reality is that we don't know. maybe life is like this very rare, very niche thing that we were very lucky to have here on Earth, right?

In our galaxy, in the hundreds of billions of stars in our galaxy, is there another one that has life, not only life open, intelligent life, technology out there? Is there more advanced technology out there, perhaps? That has me very, very curious. That would be one of the questions if I had like a genie that can answer any question. That would be, give me the number, right? How many?

And that will solve so many questions in my mind about the universe out there. But the very fact that we're talking about this and you folks are thinking that you're hearing this, you're thinking, that's an interesting question. And that's an interesting question that we could get answered. That is amazing because we are not in the realm of science fiction anymore. This is science, and we are putting task up out there to get these answers. Nestor Espinoza is an astronomer at the Space Telescope Science Institute. And I just want to give you a quick update. Since I talk to Nestor, we have a little bit more information about Trappist 1,

the planetary system that Nestor is really excited about. Using the web telescope, scientists determined that Trappist 1D, which is one of the planets in that system, does not have an earth-like atmosphere. We're still learning more about that planet and the six other rocky planets orbiting the same star. If you liked this episode, you will love NASA's documentary, Cosmic Dawn. Cosmic Dawn reveals the incredible true story

of the James Webb Space Telescope, with never-before-seen footage from the creation, construction, and launch of this remarkable telescope. See the film at NASA.gov slash Cosmic. on. And you can find the latest news from the web telescope and much more information at NASA.gov slash web. This is NASA's Curious Universe. This episode was written and produced by Emma Brambilla. Our executive producer is Katie Conan's. The Curious Universe team also includes Christian Elliott and of course Patty Boyd. Christopher Kim designed our show art. Our theme song was

composed by Matt Russo and Andrew Santaguit of System Sounds. If you enjoyed this episode of NASA's Curious Universe, please let us know. Leave us a review wherever you're listening to this podcast, share the show with a friend. And remember, you can follow NASA's Curious Universe in your favorite podcast app to get a notification each time we post a new episode. This is an official NASA podcast.