Science Friday - What We’re Learning From The James Webb Space Telescope

Episode Date: June 20, 2025

The James Webb Space Telescope (JWST) started collecting data nearly three years ago, and it has already transformed our understanding of the universe. It has spotted the earliest galaxies ever seen, and, closer to home, captured auroras around Jupiter. So what’s the latest from the JWST? In this live broadcast, Hosts Flora Lichtman and Ira Flatow talk with astrophysicist Macarena Garcia Marin, deputy project director for the James Webb Space Telescope.Guest: Dr. Macarena Garcia Marin is an astrophysicist and instrument scientist for the European Space Agency. She’s also deputy project director for the James Webb Space Telescope.Transcripts for each episode are available within 1-3 days at sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

I'm Flora Lixman, and you're listening to Science Friday. Today in the show, checking in on the web space telescope, which has been out there, low-key, answering little questions, like, what's the universe made of? And posing new ones, like, was Einstein wrong? Before launching web, every other scientist you would ask, they would be excited about the surprises, and it's given us many. And here to field your questions is Macarena Garcia-Marine. She is an astrophysicist and instrument scientist at the year.

European Space Agency. She's also, also deputy project scientist at the Web Space Telescope based at the Space Telescope Science Institute, famously in Maryland. Welcome to Science Friday. Thank you. Thank you for having me. Let's talk about this because there's so many really interesting things going on, so much exciting news. Let's start with the news this week of this super old galaxy, right? I mean, this is, to me it was mind-blowing? It was mind-blowing to me? Tell me why that is. because we're talking about galaxies that existed about 280 million years after the Big Bang. That's nothing.

It's like a baby galaxy. It's like a baby galaxy. So they discovered this galaxy going way back in time. Way back in time. And let's remember the universe is about 13.8 billion years with a B. So this is a baby galaxy. And for a baby galaxy, it has had the time to actually have stars and reaching the galaxy

and producing some additional chemical elements on top of hydrogen and helium. So it's really, really a fast way of growing. How old should it be to make those things instead of what it is now? What would you expect the age to be? I mean, it depends on when they start being. So stars, they can last, depending on their mass.

They can last between millions and billions of years. But we don't really know how this very first stars were. They may have been thousands of time. bigger than the sun. So that's... So why is your head exploding? Because this is really why

we launched the James Webb Space Telescope. The primary science case, we have to observe these very first galaxies and very first stars. And actually, this is the oldest we have confirmed with a spectra,

which is like the fingerprint or the DNA of the galaxy. So you decompose the light and can really make sure how old that galaxy is. But there are candidates that are based on imaging that are even older. They're older ones. Yeah.

They are only candidates. They are not confirmed, but because they are only based on imaging. But those galaxies, it's very interesting because they have been observed with web, but using gravitational lensing. So that is nature helping us by enlarging galaxies that are really far away. So these galaxies are fainter. and this the researchers think that probably

they are the progenitors of these other galaxies we are seeing that are brighter and slightly closer. So it is man blowing. So what is it here? Do we have to rewrite the laws of physics

or do we have to rewrite how we think galaxies form? I think we have to rewrite how we think galaxies form at that time of the universe. So things like the Big Bang the cosmological

theories we have this still hold. But we need to make adjustments to really understand how the galaxies form. It's like the chicken and the next thing. Is it first the stars, it's the black hole? How does this all come together? Did these findings make us rethink anything about our own galaxy?

I think what is making us rethink is if you go closer to us, still in a very young universe, we already see galaxies with spiral arms and even with bars. So to me that's also a surprise that in such an old universe, we already have those structures that take millions of years and billions of years to take place.

So in that sense, yes, it is really making us rethink how long do you need to make those structures. Do you have any idea on that? Can you give us a little bit of a hint? We know, for instance, that bars, at least there is one galaxy that we have seen with Webb that has a bar when the universe was about 2 billion years old. very early still.

Yeah. But these are much earlier, right? These galaxies. Oh, yeah, yeah. The first one we're talking about, they are really babies. They are bold and right, yeah. Let's go to the phones. Let's go to V in Ventura, California.

Hi, V. Hi, V. Hi. I'm on Science Friday. You're on Science Friday. Go ahead. Awesome, yes. I read a question. As of recently, the James Webb's telescope found that there was kind of a buoyed around

our multi-way galaxy. I was wondering if you had any sort of inside into this if maybe it's a possible black hole that we're going towards or if it's maybe some sort of dark matter we don't know about. A void around our Milky Way galaxy. Have you heard anything about this? Honestly not, but you've mentioned the black, you've mentioned black holes and you've mentioned dark matter. So in both areas where we're also contributing. At the center of our own galaxy, there is a super massive black hole, millions and millions of mass in there and with stars circling around,

and the material circle around. So we're looking into that with Webb, not only the surrounding of the black hole, but all the structures around it and how that impacts the environment. And when it comes to dark matter, we are also seeing via things like gravitational lensing. How does the map...

So gravitational lensing is a situation where you have, for instance, a cluster of galaxies that are really, really massive. They are so big and so massive that they bend the light around. So when you do the calculations, you find out that there is actually mass missing. So that means there is something like dark matter that you don't see, but you know it's there because it affects the light.

So in that sense, yes. Do you think that dark matter has anything to do with the formation of these mystery galaxies that you've just discovered? I don't know. That's a good question. This is one of Ira's favorite topics. I love that, yeah. Well, the truth is that there are many things we still don't understand, which is exactly.

I hear you say that. Yeah. Yeah, because a lot of people think science knows everything. No, we don't. No. But that's a good thing. Yes. That means that we still have many, many questions that need to be answered.

So we need more data and more generations of scientists really looking into this. And I've had, when we've talked about this before, I've had scientists say, you know, I like the chase more than the discovery. Exactly. The chase is great. And actually, before launching web, every other scientist you would ask, they would be excited about the surprises. and it's given us many. What are you chasing? Me, person?

I've been chasing, following out what she was asking, the center of our own galaxy, actually. We got data very recently on some structures around the black holes. I'm very excited looking into that. Are they interesting? What are you finding about that?

Well, I'm still looking at the data, so we'll see. All right, let's go to the phone. San Antonio Tali in San Antonio. Hi, welcome to Science Friday. Hi, thanks so much for taking my call. Go ahead. My question is, I'm not sure if this was an active decision that was made,

but how was it decided what direction the telescope was sent in in space? How was that trajectory decided? Wow, yeah, and what direction to find these galaxies? You mean in which direction to find the galaxy? Oh, it's a really good question. So first you go to the galaxies, you already know they are there. And for that, we have what we call deep fields. For instance, the Hubble Space Telescope looked into these deep fields,

and we knew there were galaxies that were perhaps about 400 million years or after the Big Bang. So you look into the fields you already have data, and you just observe during maybe 10 hours, and then you compare those images and do some tests to really understand if there are galaxies. Once you have candidates, then you go back and take a spectra, that is you make a rainbow of that candidate.

But yeah, the fields were, fields that were already observed by telescopes like the Hubble Space Telescope. It feels like we cannot talk about Webb without talking about exoplanets. I agree. What is new and exciting there to you? New everything. Web has opened up the field of exoplanets, which is great because exoplanets didn't even exist when Webb was conceived.

Really? Yeah, we hadn't seen them. They might have been there. Sorry, they were there. You're right. But as a science topic, we didn't know they were. there. And now there are almost 6,000 of them. So yes, it's a field that is really blossoming, lots of discoveries, lots of new molecules, observations of dayside and night side. So it's

really, really exciting and it's opening up on your field. Well, there was this recent news that I think was linked to Webb about a biosignature. Correct. On an exoplanet. Yes. Burst our bubble or tell us what the real deal is. Oh, the real deal is that that's a very bold claim. Right? Extraordinary claims. Extraordinary claims require extraordinary proof. So, of course, when that news came out,

there was a lot of excitement, but then other scientists from the community actually look at the data and they're concluding different things. So to confirm that claim, you would have to confirm the type of planet that it is and still is not clear if it's something like a mini-Neptune

or a Haitian world that is a world that is water with a hydrogen atmosphere. So we don't know the type of planet. Still not clear if the detection is solid and still not clear if the molecules that are claimed are actually the ones they are because they could be something else. And the third thing is that even if all the other conditions are demonstrated,

DMS, which is this molecule, you can also find it in. comments and you can also find it in the interstellar medium. So many open questions. When you get up in the morning, what gets you excited about what you do? Everything, to be honest. I have to say every day there is some new scientific discovery. Every day there may be a new paper. Every day there is something that, you know, the community is excited about. And then part of the work is also to bring that message to the public. It's not just about the science community. That's what you're here for. That's why we've got you.

Coming up after the break, we'll talk about what to expect from a podcast from a public. possible successor to the web. Stay with us. Hey, Ira here. You've probably heard me say many times that we are all in this together. We're so encouraged by those who have backed me up on this by stepping up to support Science Friday in the face of the current funding challenges. So, thank you to everyone who has donated in the past month. It's clear that many of you value science and count on public media as we do. You are, you, are the driving force behind our work. Your support strengthens Science Friday, provide stability in these moments of volatility, and your support is more crucial now than ever. So if you haven't

made a donation to help close the current funding gap, you can still make an impact by going to ScienceFriiday.com slash donate. Any amount you can give helps to sustain Science Friday programming in this critical moment. Again, that's ScienceFriety.com. slash donate and thanks. And let's go to the phones. Aaron in New Orleans. Hi, Aaron. Yes, hi.

Thank you much for taking my call. I did have a question. You know, I actually changed it to a much better one if that's okay. We'll be the judge of that. Go ahead. Okay, thank you. What I wanted to ask a guess was, was that what is her opinion on the amoe-a-moo object?

Do you think that this was something from intelligent life? Or do you think this was just a blip from another solar system that just happened into ours? Glad you changed your question. That was a good one. Yes. Yeah, that's a really good question. Personally, I think it was a quote-a-quot object or visitor from outside of our solar system. As we were saying before, the claim of life or intelligence or anything like that,

it requires really lots of proof, and we don't have that. His original question, which I had was whether the budget cuts are affecting your research and the research of astronomy and NASA and all stuff that you do. So at this point, we don't know, and that's a question better addressed to NASA in terms of what's going to happen. But you don't feel it yourself at this point? At this point, no. What I feel and what I can really say is that the observatory is performing incredibly.

The community is exciting and the same. science coming out of it, it's really something worth pursuing every single day. You know, I think for the public and for someone like me, a lot of what I see from Web are these beautiful images. And they bring me so much joy and so much pleasure. But I wondered for you, for astrophysicists, like, do you learn something by looking at the images? Or is it really just the data that underpins it that you're interested in? We learn a lot from images. And actually, often you first use the image to identify candidates of special galaxies or candidates of something, and then you take a spectra.

Because with imaging, you have much bigger feel of view. You cover lots of space. But also the different colors you use to create these beautiful images. It's a thing of, in the visible would be red and blue and green and all that. So you have infrared colors. These colors give you a lot of information. And all of these beautiful images, you see, they are also used to the science with him.

So is it like a where's Waldo where you're like, oh, look, there's something in the corner that looks interesting, let's follow up, it is. Are people better at looking at the images than let's say AI? I mean, if you've got a bunch of people together to find stuff? I think there is a bit of both. I think the future of astronomy,

I mean, the future of many missions is to have large, vast amounts of data. So there's going to be some sort of machine, techniques that can be applied for that. But behind that, I think, personally, you always need a person with a brain that can do the interpretation and actually the figuring out exactly what's going on. And the web was specifically made to make these kinds of discoveries, right? What tools does it have to do that? It has four science instruments. They all operate on the infrared. So that's the type of light we don't see. But it's really, really good to

see cold objects and to peer through the dust and to see very distant objects. And we have about 75% of the time with your spectroscopy. So all of the four instruments have spectroscopic modes. We have a vast array of spectroscopy, and that means essentially we break up the light into a rainbow. And with that, you can really understand what's going on. And they also do imaging. We do chronography, which is a technique.

where you can block the light from a star, for instance, and see the planets around. Yeah, you need to do that. You do that as well, exactly. So we do have a lot of scientific power behind all of the instruments. What's happening? I know already we're talking about a successor to the web, right? The Roman Space Telescope, how would that be different from the Webb Telescope?

What would it do differently? Roman will be different because it will look into a different wavelength. And also it's a different concept. Roman will do lots of surveys, really large field of view, covering large portions of the sky. And what do you learn by doing that? Well, you can,

there's going to be a lot of learning on transients. That is, transience is that you go to a region of the sky and observe it, and then you go back again and look for things that have changed. And that could be supernova,

that could be galactic nuclei, black holes active, etc. I see you're not excited at all about this kind of work. I want to thank you for taking time to be with us today. Thank you. Macarena Garcia-Marine is an astrophysicist and instrumental scientist for the European Space Agency, also Deputy Project Scientist for the Webb Space Telescope. Thanks for listening. Don't forget to rate and review us if you like the show. And you can always leave us a comment on this segment on Spotify. We'd love to hear from you. Today's episode was produced by Annette Heist. But a lot of folks helped make this show happen.

Every single week, including John Denkoski. Danielle Johnson. Beth Rami. Jackie Hirschfeld. I'm Flora Lichtman. Thanks for listening.