Lab Notes: The telescope redefining the Universe

Australia Broadcast Center

10-07-2025

Belinda Smith: Three years ago this week, a telescope sitting in space 1.5 million kilometres from Earth gave us a view of the cosmos we'd never seen before.
News Grab: The $13 billion infrared unit is expected to revolutionise astronomy.
Belinda Smith: Faint, distant galaxies snapped into sharp focus in the first photo. The telescope also revealed the steamy atmosphere shrouding a hot gas giant planet. And gave us a rare glimpse into a star nursery inside our own galaxy, the Milky Way.
News Grab: NASA says humans have never before gained such important information about the universe.
Belinda Smith: In the years since, the James Webb Space Telescope has pulled back the veil on a whole bunch of mind-blowing cosmic phenomena. So how has this telescope changed our understanding of the universe? And what is still to come? Hi, I'm Belinda Smith and you're listening to Lab Notes, the show that dissects the science behind new discoveries and current events. To give us a rundown of some of the James Webb Space Telescope's greatest hits, so far, is Laura Driessen, a radio astronomer at the University of Sydney.
Laura Driessen: I think there was a collective gasp around the world when those first images were released because they were just so gorgeous. I can't tell you exactly where I was or anything like that, but I definitely remember seeing those first just beautiful images.
Belinda Smith: What's so special about the James Webb Space Telescope?
Laura Driessen: From an engineering perspective, it's just an amazing feat that they put a whole telescope and it was sort of folded up like origami. They sent it really, really far away to a spot that we call L2 and then unfolded it and it actually worked. That's amazing. I'm sure that everyone at NASA was doing the collective holding their breath thing because that would have been pretty stressful. The thing about JWST compared to Hubble, we can't go and fix it. If it breaks, that's it.
Belinda Smith: It's broken. Wow. One and done situation.
Laura Driessen: So it was a huge risk when they sent it up, but everything had worked perfectly on the launch. So, you know, maybe they were feeling a little bit more comfortable, but I think it's just stressful when you do anything like that.
Belinda Smith: I've seen the JWST described as doing infrared astronomy. What does that mean?
Laura Driessen: So there's all different kinds of light. The type of light that we can see with our eyes is called optical or visible light. And it's really just a teeny tiny little slice of all the different kinds of light that exist. It's in the nanometers part of the spectrum. So each little wave is nanometers, which is you divide a meter into a thousand, that's a millimeter. Another thousand is a micrometer and another thousand is a nanometer. Oh wow. So really tiny wheels. A thousandth of a thousandth of
Belinda Smith: a thousandth of a meter. Yes,
Laura Driessen: exactly. And the longest wavelength we can see is red. And if you keep going longer, then we get to infrared. We usually think about infrared as sort of heat. That's how we experience infrared light. For example, a fire would be quite bright in infrared and that's what we feel as heat. So it's a different kind of light that's invisible to us.
Belinda Smith: That's infrared light is what the JWST sees. But...
Laura Driessen: That also means the colours you see in the JWST images aren't real. That's us adding the colours because it's light we can't see. We don't have a colour for sort of invisible light. That wouldn't help if we just showed invisible light and you couldn't see anything. So we add the colours later.
Belinda Smith: Sure, those pretty pictures wouldn't be so beautiful. So in the three years since the James Webb Space Telescope sent back its first batch of images, we get treated to new cosmic insights on the reg, really. So how has it changed our understanding of the universe?
Laura Driessen: Ooh, I think one of my favourite things is from a cosmological perspective. So that's a subset of astronomy, but it's thinking about the universe as a whole. And because JWST can see things that are more distant, it's discovering things like black holes and galaxies further back in time than we thought that they existed.
Belinda Smith: Yeah, it can see back in time, so to speak, because the telescope picks up light that may have travelled for billions of years. So it's really seeing, say, a galaxy as it was all that time ago, maybe even from the baby universe.
Laura Driessen: So one of the main things is the universe started and expanded and there's a time period at the very start that we can't see anything because it's kind of foggy. There's just a whole bunch of electrons, very foggy. Then there was a flash in the universe that we could see when things cooled down enough that the fog kind of demystified. And then there was a period called the Dark Ages, which sounds very fancy and dramatic. And it's also a time period when the light couldn't escape. So at the start we had a fog of electrons, then we had a fog of hydrogen, so we couldn't see. After that time period, the first stars started forming. And that's called the cosmic dawn. We're very dramatic as it turns out. And that's when we start seeing light.
Belinda Smith: The JWST is helping push back when this cosmic dawn, well, dawned.
Laura Driessen: This is really interesting from the perspective of how our universe changed over time and how we started with kind of just a mess and ended up with the beautiful things that we can see in space today, planets, stars, galaxies, all that good stuff didn't just happen. And we're trying to work that out. So telescopes like JWST, as they push back in time, seeing black holes earlier than we thought we saw black holes, galaxies earlier than we thought that galaxies could exist, changes how we think about how the universe evolved.
Belinda Smith: So the universe's early years are taking on a slightly different form.
Laura Driessen: Yes. And I think this also, I think about like our parents when they were kids, they didn't have many photos. So when we look back, we're trying to work out what happened when our parents were kids and what sort of mischief they got up to and how they turned into the people they are today. We just don't have that much information. So JWST is like adding photos. You found a lost album. And now you can find out what your parents got up to.
Belinda Smith: The universe is about 13 billion years old. What time scales are we talking here for the universe's dark ages? Between that electron fog and the cosmic dawn.
Laura Driessen: Their estimates are a bit iffy, but I think JWST saw a galaxy 400 million years after the Big Bang. So that does sort of put a limit on the dark ages from 400,000 years to 400 million.
Belinda Smith: OK, so what else has the James Webb Space Telescope told us about the universe?
Laura Driessen: So one of my favourite ones, which is not as big in scale, much smaller in fact, is something called a jumbo, which is a Jupiter mass binary object. And these are planets, two planets in a binary, wizarding around each other with no star. So they're just planets existing. So
Belinda Smith: planets, generally we know of planets orbiting some kind of star, like our solar system. But these ones don't. So did they ever have a star? Have they run away from the star? What's happened? Well,
Laura Driessen: we don't know about these ones. So the fun thing is rogue planets are a thing we've already known about. So these are individual planets that through gravity, either a star, you know, say another star coming too near the solar system might kick out some planets through gravity, or planets in amongst themselves sort of having gravity interactions and one end up popping out. So we know about individual rogue planets. But having two planets that are kicked out but somehow stay together? Tricky. And planets don't really form on their own. So maybe these things were flung out, but somehow stayed together with a friend because they found about 40 of them in the Orion Nebula. To call them planets is maybe pushing it. That's why we call them objects. That's sort of an astronomy term for thing in space we don't have a better name for yet. But they look like planets and they're just whizzing around each other on their own. So a little bit of a challenge to planet formation, solar system formation and star formation that they were even seen. This is one of the things we never thought we'd see when we turned on the JWST.
Belinda Smith: Something else the James Webb Space Telescope has shed light on are exoplanets, planets around stars outside our solar system.
Laura Driessen: We just don't get pretty pictures of those. This is where that spectra comes in. And that's one of my other big favourite things of JWST is something called transmission spectroscopy of exoplanets.
Belinda Smith: What is that and why is it important?
Laura Driessen: So spectroscopy is where we can identify chemicals in space. So some of you might remember when you were in high school doing things with Bunsen burners where you sprayed different chemicals on the Bunsen burners so they light up different colours. Basically every element in the periodic table and all the molecules as well, so like carbon dioxide, water, where it's atoms all smooshed together, has their own signature, a little set of colours that every time you see it, they have that set of colours. And we can use that to look into space. We only have light so this is what we've got to work with to identify chemicals in space. And JWST has the instrument on there that can do this. So in the infrared still, identifying these lines, different wavelengths or colours that identify different chemicals and molecules in space. But what we're doing here is we're trying to detect the atmospheres of exoplanets. And that maybe doesn't sound that dramatic but you have to remember it wasn't too long ago that we'd barely detected any exoplanets at all, let alone trying to see their atmospheres. And atmospheres around planets are teeny tiny.
Belinda Smith: Yeah, it's like a thin shell of gas. Or some liquid maybe but it's not much.
Laura Driessen: It's not much at all and this is why we call it transmission spectroscopy. So as the planet passes in front of the star, we see a little dip in the light of the star and that tells us the planet's there. But as the planet passes in, you're also getting light from the star going through its atmosphere. So it's transmitting through the planet's atmosphere. So we're sort of using the star's light as it goes through the planet's teeny tiny atmosphere to see what molecules and things are going on in those atmospheres.
Belinda Smith: So it's kind of like a stained glass window. Yeah,
Laura Driessen: so you're shining a torch through the stained glass window basically to see what colours are going on in there and that's what we're doing. And it had sort of been done at a very basic level before JWST but now it's just sort of happening all the time. The one thing we want to do which hasn't yet been done by JWST, not for lack of trying, is to try and detect an atmosphere around a rocky planet. So we're pretty good at it for things that we call hot Jupiters. So Jupiter's a big gas giant. Neptune's which are also kind of gassy. But for it we want to do like the Earth. We want to see a planet that's kind of like the Earth, a big rock, and we want to be able to detect the atmosphere.
Belinda Smith: Why do we want to look at rocky planets?
Laura Driessen: So when we search for life, we're talking a little bit about aliens here, when we search for life the only model that we have is us. So we sort of think that if we're looking for what we call a habitable planet where there might be life, we're looking for planets that are like ours. Rocky, we sort of think that's what we need. I don't think we'd survive very well on Jupiter. Rocky, not too hot, not too cold, water is wet. Those are sort of the basic things. But we also know that we need an atmosphere. We love our atmosphere. It protects us from a lot of things and also breathing is great.
Belinda Smith: The thing is, for a planet to hang onto its atmosphere, it really needs a magnetic field. This protects that atmosphere from being swept away by stuff spat out by its star. Take Mars, for example. It once had a magnetic field, but that's no longer.
Laura Driessen: So over time, basically the sun has just kind of bombarded it and it had a really nice atmosphere and it's slowly just blown away by the sun. So that's what we want to see. If ours is sort of special for any reason, it can't be that special, the universe is infinite. But how common is it for these sorts of planets that are nice for us to live on? How often do they happen? That's one of the questions. Exoplanets is a great field, looking for life. It's fun. We really are in this era where we're seeing things we've never seen before.
Belinda Smith: That was Laura Driessen, a radio astronomer at the University of Sydney. Thanks for listening to Lab Notes on ABC Radio National, where every week we dissect the science behind new discoveries and current events. I'm Belinda Smith. This episode was produced on the lands of the Wurundjeri and Menang Noongar people. Fiona Pepper's the producer and it was mixed by Tim Symonds. We'd love to hear from you. Send us an email labnotes at abc.net.au. Catch you next week.