Seeing exoplanets directly with Dr Vito Squicciarini

Welcome to Growing Worlds, the podcast where we explore the science of exoplanets through conversations with early career researchers on the front line of discovery. I'm Lorenzo.

I'm Jenny. In each episode, we meet a guest who takes us behind the science of planets, stars, and the methods we use to study them.

Most of the time we detect exoplanets indirectly, through transits or radial velocities. We see their effects on their stars, but today we are talking about something much more ambitious, actually seeing planets directly.

To guide us through how that works, we're joined by Dr. Vito Scuicciarini from the University of Exeter. Vito, welcome to Growing Worlds.

Hi, thank you. Thank you, Jenny. Thank you, Lorenzo. I'm really happy to be here.

good, we're excited too. It's so cool, direct imaging, we'll get on to that in a second.

I will try my best to explain how it works.

you'll be fantastic. Don't you worry.

Vito is an exoplanet researcher based at the University of Exeter, where he works on the discovery and characterization of planets beyond our solar system with a particular focus on direct imaging. His research centers on taking actual images on young giant planets and brown dwarfs. So, using those observations to understand how planetary systems form and evolve.

Vito also works in Paris on large direct imaging surveys, helping to place some of the most precise constraints on how common are giant planets. Altogether, his work sits at the intersection between observation, data analysis and modeling.

helping us to turn images of distant worlds into actual physical understanding.

So Vito, let's begin at the beginning. It's a very good place to start. How did you get into exoplanet science and what drew you into direct imaging specifically? Where does the journey begin?

So, yeah, good question. I think that my journey began when I was a kid because

Mm-hmm.

I've always been interested in science generally and I've always been a keen reader of anything related to, from geography to geology to...

biology and physics and astronomy and so on and also sci-fi of course and at some point I decided maybe I was 10 I decided that astronomy was my best subject into the entirety of science and at some point when I had a few years later when I was 18 and I had to to choose my topic for the university, I decided to enroll to physics but at a university that is in Padova in Italy that is really focused on astronomy because I knew that I wanted to go to astronomy after my bachelor and then I had no clear idea about which subfield of astronomy to get into. I think it was just related to the interest that I developed while I was studying in my master at the university. And so I went... Sorry.

I was just going to ask, when you were a child, was it just kind of like the amazing books that you were reading or were you inspired by any like dark skies or movies in particular or was it more the kind of the books?

Yeah, I think there were a couple of things. So, from the place I'm from it's not very easy to see the stars, know, I don't

Mm.

have really a good sky.

See, this is why you study things that we can't see from the ground. Yeah, there you go! It was there!

Yeah, that's a good way to put it. But it's very easy, of course, like anywhere in the world to see the moon. And I was really fascinated by the moon.

Mm.

And this is... part of the answer. The second part of the answer is that I had some amazing atlases from the 70s, I think. They were

wow.

my mother's and so I was, they had really nice pictures of the planets seen from the telescopes of the 20th century. And I think maybe it was the end of the 70s that there were the first pictures of the Voyager and the Pioneer spacecraft. And so there

Yes, yeah. Yeah.

were these amazing pictures and it's something that made me fell in love with planets in general

Yeah.

and that probably I retained in my memory somewhere.

Yeah so then all the way through school it was just lurking about in the background and then just started coming more to the forefront as you continued with your degree.

And how did you end up in direct imaging? And most importantly, what is direct imaging?

To answer the first part of the question I ended up in working in Direct Imaging just due to my particular path after my master. After my master there were some PhD programs that were available in Padova and I got particularly interested in one specific project with a professor working at the Observatory of Padova that was related to Direct Imaging.

that was something that I knew nothing about at the moment. So what is Direct Imaging?

as the name says, Direct Imaging means to take photographs of distant exoplanets, which is something that we can't do usually. Because we know that we've discovered more or less 6,000 exoplanets to date in the last 30 years, but we have...

a direct image of just a few tens of them, so think 70 or 80 of them. That's because usually the vast majority of exoplanets have been discovered through indirect techniques, meaning that these planets either pass in front of the stars causing an eclipse that makes a star a bit dimmer, This is called the transit method.

is that as the planet orbits a star, also the star orbits the planet in a sense because it's a two-body system and both objects orbit around their common barycenter and so we can see that the star wobbles a bit and through the wobbling we can of the star we can identify that there is a second object that we can't see but causes the wobbling and this is something that we can explore through two techniques one is known as rudder velocity and the other one is known as astrometry then there are other fancier techniques that are a bit difficult to explain Direct imaging conceptually is very simple because it's very similar to what to do if you when you take your telescope you go out with a friend on a dark night and you point it at let's say Jupiter if you point it at Jupiter and you have a good enough telescope you can see that most of the time there are some there are one two three up to four very bright satellites that you can see close to Jupiter the idea is that you can see something that is quite dim close to something that is quite bright just because there is some light coming from the secondary object so if you replace now Jupiter with a star and the satellites of Jupiter with planets this is the idea behind Direct Imaging And then, of course, it's much more difficult than that. There are a lot of technical aspects that we have to account for. And also, you can't do this at home. You need a telescope that is as big as a cathedral. But apart from that, this is the idea.

Wow.

You

Can you take us through some of the difficulties? Because stars are so bright, and planets are dim. So that's got to be one of the problems.

Yeah, that's exactly the problem, Gianni. That's the main reason why this is difficult. It's because if you point with the telescope at a star, and you try to take a picture of the star, you will be completely dominated by the light of the star. Because planets are intrinsically millions to billions of times fainter than the stars.

and so it means that for each photon that you receive from the planet you receive typically billions of photons from the star and so a first thing that you need to do is that, that we do with direct imaging is that you need to cover your star you need to put a mask in front of your star because by placing

Okay.

a mask in front of your star then most of the light coming from the star does not enter the telescope so this is the first... let's say... way to get rid of most of the cellar contamination.

like, you block out the starlight. Is it literally like a piece of metal in the way, or is it some fancy, clever imaging techniques to sort of cancel out the starlight?

so

I would

it's

like to compare it to a post-it in front of your telescope.

Yeah, so it's typically

Yeah.

a combination of the two things because

Okay.

you typically put something physical in front of your telescope but also you try to apply certain techniques in order to enhance the effect of masking so it's a combination of several different things but the net effect is that you remove the vast majority of light from the star. Then there are even if you do that, in any case there is some light that still leaks and this is something that determines the final sensitivity of your instrument and the sensitivity is at the moment not really comparable to the one that we get with different techniques meaning that we can just observe planets that are incredibly bright planets that are

Okay.

much brighter than Jupiter So I can't study, at least for the moment, can't study planets like the Earth. I need

yet.

to study planets, not yet. I can't study just planets, the so-called giant planets, so planets like Jupiter

Mm.

or bigger than Jupiter, but

Yeah.

that must be also very young. And why is that the case? Because very young planets, and when I say very young, I mean a few million years, a few tens of million years, or up to a few hundred million years.

So these kind of planets are still hot because they retain the heat of deformation. You have to imagine that when a planet forms it accretes material. So when it accretes material of course it means that there are a lot of impacts and so the planet is hotter than it is when it's old and then it loses heat over time so it gets cooler and gets dimmer because the hotter the brighter.

So if it's heat that we're thinking about, does that mean that we're observing in the infrared compared to

Mm.

in the optical for direct imaging? Because I guess as well then the star itself is dimmer because most stars emit most of their light sort of in the optical range, unless they're like red dwarfs, right? So are we in the infrared region now?

Yeah, you're completely right. Indeed, as I was saying, we are tangeting these young planets and so we are having a look at their thermal emission, so their intrinsic emission and not the light that they reflect from the star, that is a reflected light, which

okay.

is a key point because for these planets the amount of light that they reflect is much less than the amount of light that they emit due to the heat. And that's one...

Okay.

That's one of the reasons, and second one is the one that you said, to go to the infrared. So yes, we go to the near-infrared, we observe from, let's say, usually 1 to 2.5 microns from the ground at least, then it's possible also to observe these planets from the space with the chain-swept telescope for instance, and we can go much farther away in the infrared.

This is something that we can't do very easily from the ground for some reason. One reason is that we have an atmosphere that absorbs a lot of

Yeah.

light. Yeah. Yeah, it's super annoying. Yeah, if we could get rid of the atmosphere, we could. Yeah, it's really much better.

All that pesky water, keeping us alive. So annoying. So we're looking at the light directly coming from the planets. So what does that mean we can learn about it? Because I guess if it's reflected light or emitted light, we can learn different features about the planet. what can we actually learn about these worlds?

So, I would say that the very fact that we're able to see a planet, meaning that we can see in our images another source that is not a star, means that we can disentangle the photons coming from the star and the photons coming from the planet, which is something that is incredibly difficult to do for the other techniques in which we just have the light of the star that filters through the atmosphere of the planet. And so this means that if we have a spectrograph, if we are able to split up the light of the planet into its different component wavelengths, we can have an idea of the main molecules that are present in the atmosphere of the planet.

What? That's so cool! No, so carry on. Please carry on. Yeah, I'm just amazed.

Yeah, no, that's super cool indeed because the molecules tell us a story. They tell us a story about how these planets form. So I told you that these planets are very young and so the presence of certain molecules implies that they might have formed in a certain location in the disk or they might have gained material from certain portions of the disk.

and so it tells us a story.

so then you can be like did they move like did they form here or did they form somewhere else and then get dragged in towards the star for example or

Yeah, so that's the idea. the idea is that we can get a lot of understanding. For instance, we can detect water from time to time. Of course, these planets are not the kind of planets around which we can look for life, but still they have water.

Yeah.

They might have water because water is one of the most abundant molecules in the universe. But the presence of water, the amount of water compared to the amount, for instance, of CO2, or the amount of methane, the amount of ammonia or sulfur-bearing species and so on, can tell us interesting stuff about how these planets came into being.

And how do you identify molecules using direct imaging? I can realize that that is water. I mean, it's taking pictures of the sea, right?

Yeah. No, okay.

Just aliens, like, around in their pools.

Especially in giant

yeah, have to thank you Lorenzo because you gave me the opportunity to specify that when we see planets, we see just a few bright pixels. We don't see the surface of the planet. It's just, you know, in the same way that we see stars with our own eyes, we can't see any feature of the surface of the stars. We see that there is something bright that seems a point.

Mm-hmm.

So that's exactly what we see in our images. And the way that it works, I would say it's much easier than what you're used to, because as I said, there's no contamination from the star. So we just see the spectrum of the planet and we can easily

Mmm.

compare the spectrum of the planet with theoretical spectra that are in spectra by modelers that have studied the atmosphere of a planet that has a certain temperature, a certain gravity and a certain composition.

By comparing these templates with the spectrum that we see, can understand if there is absorption, for instance, from a certain molecule.

Last year we discussed a lot about transmission spectroscopy for exoplanet and we saw that different wavelengths correspond to different sizes of the planets because of how molecules react to light. What you were describing is something similar, isn't it? So, different colors of the light you can see different...

amount of light coming from the planet? Is this a correct interpretation?

yeah definitely because if we had no absorbing molecule at all we would just see an emission that is known as a Planckian function so we would see a certain shape we would see a very precise shape of the so-called spectrum that is basically the amount of flux that comes to us as a function of the wavelength in which we are we are observing and this is a function of the temperature of the the planet but as soon as as you are saying we start to add molecules each molecule has certain specific wavelengths in which it absorbs light and so we're gonna see that the flux in this particular bands is going to be lower than the one that we expected so if we see these these dips we we can understand that Maybe there is this molecule here that is causing it.

Mm.

Okay, so in my brain now this is like if the planet has nothing it's like a cannonball it's just hot but nothing else you basically see a cannonball. If the planet has something on top of it so you put water on your cannonball and you change wavelength so you change color in the light you don't see a cannonball anymore you see a little hole or a blob or something slightly different so a different wavelength, we actually see kind of different planets, we can say.

Yeah, yeah, yeah, think it's a nice way to put it. I would say that depending on the wavelength slice we see that the planets in our images becomes slightly brighter or slightly dimmer, but if you

Okay.

just measure how bright it is at every wavelength and

Mm-hmm.

you draw a plot, then you get the spectrum. That is what

Yeah, of course.

we check against our model, but yeah, that's exactly the way you put it. in a more poetic way.

So it's not just identifying the molecules that are there, but it also reveals things like temperature and atmospheric

Mm-hmm.

pressure, right? So you really truly get to understand these worlds by looking at them.

yeah unfortunately yeah we can't really say a lot about the the atmospheric pressure because of course of course you know, ideally if we had the best instrument that you can think of, if we have unlimited money we could beat an instrument that has just infinite sensitivity and infinite precision but since this is not the case we are quite limited so we can say that maybe there is this molecule, there is this molecule and so on we can say that this is its temperature but we are not yet able to run very complicated retrieval analysis in the same way as it's done for instance for transmission spectroscopy with transits. what I want to say is that in a sense we are trying to use similar techniques to what is being used with other methods but it's just much easier I would say just because we do not have the yet the sensitivities to prove down all the smaller details that other people are already measuring transitive planets.

Can you figure out the mass and the radius through direct imaging?

the short answer would be no but the short

Yeah, come on! We have time!

Let's go for the long one. Let's bring us hope now.

answer is no because as i said you just see a point of light so you have no idea

Mmm.

of how big it is and also yeah you don't have any relative measurement compared to the star as we transit when you know it covers

Mm.

up a portion of the surface of the star so you have an idea of the fractional area that is covered you don't have anything like that what you do have is the fractional flux compared to the star so you know how dimmer the planet is compared to the star so this is the only observable that we have but we also know that the star we know quite well the luminosity of the star in the wavelengths that we are observing because we have catalogues and so on so we

Mm-hmm.

can quite easily understand the absolute luminosity of the planet and so this luminosity of the planet as I said before as the planet cools down over time it's something that depends on time so we need to know the age of the system and we typically assume that the planet has the same age as as the star, which is more or less true. When I say more or less I mean that within a few million years it is true. And so this means that if we know the edge of the star, then we can just use this edge information, couple it with the luminosity that we measure and use a model that describes how bright a planet of a certain mass looks.

And so we can determine

Okay.

in this way the mass, the radius and the temperature and so on.

you'll know as well like how far away the planet is from the star so then you can factor in how much it's getting irradiated.

So yeah, we do know how far away it is but beware that here we are measuring the emitted light, it's not reflected light so this is is the light

Okay, so that doesn't matter.

yeah it doesn't matter it's exactly the same regardless of the distance of the planet to the Sun

Okay, cool.

have another question.

Mm-hmm.

How deep into the planet can you see with direct imaging? Because you are seeing the light coming from the planet. So I'm wondering the light coming from which layers of the planets if you can determine this. Because I don't know if you remember like Google Earth when you can give an address on Google and it's zooming and you go through clouds. You could zoom on the house and you see the poor house owner which is watering the plant in his garden.

Yeah.

Do you see the light coming from that water on the plants or you only see the light only with a lot of good marks? The light coming

Yeah.

from the clouds surrounding the planets. How deep is

So I would say that we are not really able to get quite deep into the atmosphere and not able really to quantify it but so these are giant planets so basically they are fully covered by an atmosphere so the atmosphere goes deep down till the core at some point it becomes something weird that is not liquid not gas anymore so there's not really the sarcophagus Contrast that we have for a nerf like planet between the atmosphere and you know the surface but that being said So You can have the formation of clouds at different heights in the atmosphere and Clouds that are too deep in the atmosphere. I'm not an expert on that so I can't put precise numbers but when the clouds form in layers that are too deep you can't see their features anymore so in a sense we are limited to the upper portion of the atmosphere and this is interesting when we are looking at objects that have a temperature around 1000 K or something like that 1000 to maybe 1200 or 1300 Kelvin because there is a very stark transition in the color that this planet has that is called the LT transition so you know that we have the spectral types for stars we have the OBAFGKM classification that depends on the temperature and on the spectral lines of the star so people have extended to cooler temperature this classification and so we have spectral types also for brown dwarfs that are objects intermediate between stars and planets and also for giant planets and so below the type objects that are stars we have the l type objects then we have the t type objects and then the y type objects and the y type objects can go down to a few hundreds of Kelvin so they really get

to.

to Jupiter temperatures but it's very interesting at some point that when you go when you pass from an L-type to a T-type object there is a stuck transition so plants become when they get cooler they become much bluer just abruptly because

Okay.

Hmm

there is it's not entirely clear but The main idea, what should explain at least the majority of the process is that there are cloud decks that for hotter objects are quite up in the atmosphere and let's say make the planets quite red but at some point as the temperature decreases they get deeper in the atmosphere you can't see them anymore and the planet becomes much bluer.

They're just cool headed.

Yeah.

Hey.

It's so exciting. What have been the biggest revelations so far from these kind of observations?

Yeah, good question. I would say that the favorite system that I have discovered by Direct Imaging is HR8799, which is a fantastic system discovered in 2009. You know that?

I know this one! It's got like, is it three or four that you can see and they've

yeah. Yeah.

imaged it over a long period. Yeah, I'll let you tell the story.

Yeah, exactly, it's exactly that system and it's really majestic because it has four planets and since we've been observing it for 15 years now, even more, so we have movies of the planets that are just going around, are orbiting their star, so this is a fantastic object, a fantastic system.

I love this one because there's so many GIFs and I love a GIF. can actually

Yeah.

see them orbit, like you can see them moving in their orbit. It's just amazing.

Then there are other planets which are really interesting, there is for instance Beta Pictoris B which is quite famous too, that was discovered also in 2008. It's a system that has two planets, a B and then a C planet, it is also a giant planet and I'm talking about planets around 8 Jupiter masses, so there are some very big planets compared to our solar system, but of course you can't...

you should imagine that these are planets that are much easier to detect because they are brighter and this is peculiar because it also has a debris disk so it has something like let's say the Kuiper belt in our solar system

Mmm.

so it has a belt of let's say remnant remnant dust from formation that is just there and that has a shape that is affected by planets so there are systems in which we see a planet we see a debris disk we can try to understand how they are interacting.

So I guess direct imaging is all about really understanding those early days of giant

Mm-hmm.

planet formation.

Yeah, it is indeed.

But what about the Earth-like planets? Because the thing is, I know you said at the beginning that we can't directly image Earth-like planets yet, but how far are we away from that? Because I think, you know, the day that we get, you know, a few pixels of light from an Earth-sized world, whether or not it's like our planet, because, you know, we so often interchange Earth-like and Earth-sized, and the thing is, it's like Venus is Earth-sized, it's not Earth-like.

So we have to be so careful with

Mm-hmm.

the terminology, but how far away are we from sort of earth-sized worlds and seeing them?

Yeah, we might not be too far from that because it also depends on what you define as interesting. you know that now people are building the ELT, the extremely large telescope in Chile, which is going to be the biggest telescope ever built by mankind.

with a diameter of 39 meters, biggest ones. Yeah.

I can't even imagine it, you know? Just, they're like trying to visualize a telescope. Like 30 meters, what is that? That is, the average door is like two meters tall, right? So it's like 15 doors and I can't even picture that. It's like bigger than my house, far bigger than my house.

It's...

I think it's ten floors. Yeah, it's three meters. Yeah. Yeah.

Yes, it's ten floors. Because if a floor is three meters, it's basically a building of ten floors.

It's 10 floors.

And this is the diameter.

Just think about that, like a 10-story building and that's how big this telescope is. It's just astonishing, isn't it?

Yeah, and this is just a primary mirror, but if you consider the entirety of the telescope, that of course is much bigger than just a mirror, it is much bigger than a cathedral. Yeah. Yeah. So just

Yeah, because you've got all the warm rooms and the casings and yeah, skycra- Yes, yeah, the cathedral thing does now.

Yes, that's what you said in beginning, bigger than a cathedral. Yes, now makes total sense. Yeah.

to give you a comparison, the telescopes that we're using now, the best that are currently operational from the ground, have a diameter of 8 meters. or less, so we're passing from

Mm.

8 to 30 meters. So with this telescope

Yes.

there will be several different instruments, There will be Matisse, Mikado and the PCS. And especially the PCS, which will be operational at some point at the beginning of the next decade, should be able to image for the first time super-earth planets and...

which we don't have in our solar system as we've learned.

which we don't have in our solar system and of course it's a big puzzle because we don't know exactly when the transition between super-orbs and mini-naps and so on and the ELT will start to be sensitive to some of these planets and so we don't know what we will discover if we will be able to detect something in their atmospheres and so on it's something really open and It's the kind of thing that will probably be led by discoveries at some point. And also there are other projects that have not been approved but you might have heard of the habitable world observatory. Yeah,

I have, but tell the audience all about it.

so it's a concept. It's a concept of a space mission that should be quite extended in infrared from I don't remember on the front top of my head but it should be from a few microns up to maybe 20 microns so a large coverage in the infrared and that would be able for the first time to do direct imaging of Earth-like planets around them stars so not exactly the kind so the M stars are the small red stars that have a mass of 10, 20, 30 % of the mass of the Sun and

Mm-hmm.

that are the most common stars in the universe. So of course

Mm.

around these kind of stars it's much easier as you know to detect planets but it's not granted that these planets behave in the same way as the Earth does from the climate point of view.

Yes.

So it will raise a lot of questions, yeah.

Lots to look forward to. Yeah, loads to look forward to though in the world of direct imaging.

And then there is also an idea of a space interferometer, which is a crazy concept, it's called LIFE and it's something for the

Okay.

late 40s or early 50s, I don't know if it will

Okay.

be ever approved, but the idea is to put four different telescopes that just form an array, something that is called an interferometer, so you have the light that arrives from four different telescopes, it combines

Mm.

and based on the interference pattern that you have, you can reconstruct an image that is a much higher level of detail, let's say, compared to a single telescope. it's something... No, it is magic. No, it is magic. But, okay,

Yeah, I find interferometry like magic. I, it is, it's just like, yeah, it is.

Yeah, it's definitely black magic I

do you know... have you heard about the images of the supermassive black holes in our galaxy or in

Yeah, yeah.

other galaxies? so it's exactly the same technique but applied to exoplanet and so this has to image for the first time earth-like planets around sun-like stars in reflected light so... I don't know We may see it in a couple of decades maybe.

in a few decades. That's

Just wait, stay tuned,

right. Yeah.

we're gonna be there!

Yeah, we've got loads to look forward to. That's what it means. guess like direct imaging is such a young field, right?

Mm-hmm.

So that there's still so much more to look forward to.

And you, dear listeners, just stay tuned on our podcast in a few series, probably,

Yeah

a few seasons, we're gonna be there for the direct imaging of Earth-like planets, yes.

In 30 years? Yeah.

Okay, I can tell you something about this because I had a talk at some point, a presentation with some kids of primary school at the beginning of this year. And at the end of the presentation, I said, okay, so it's gonna take maybe 20 or 30 years to reach the level of technological advancement to discover life. So maybe one of you here will be the one that discovers it.

That's true.

And there was a huge wow in the room.

It's their turn. We are building

Yep.

this for them.

Yeah.

Yeah, I because in 30 years, I like to think I'll be retired. So you're exactly right.

That's great, Vito. This has been so, so fascinating. Unfortunately, we are toward the end of our time together, so I got to ask you our signature question. It's a difficult one, but it's always a fun one. So if you had to choose one celestial body that represents you or your work, what would it be and why?

Okay, I have Because it tells a story, I think. So it would be HD143811ABB, which is an awful name.

I'm impressed that you came

I do remember that.

out with that. Yeah, exactly.

because I've written it so many times.

You

So it's a planet that my team and I discovered in 2024. So actually we confirmed it in 2025, we first saw it in 2024 and so it's a particular planet because it orbits a binary So it does not orbit a single star, but it's a bit like Tatooine from Star Wars that it orbits two stars.

I'm dreaming now

And so it's a planet that was the outcome of a big survey. So when I was in Paris for my first postdoc, I had the project of reanalyzing some huge collection of archival data.

So there were around 600 stars observed over the course of 10 years with an American telescope named GPi and I had to reanalyze all the data from scratch using some new data reduction techniques, some new algorithms that are more powerful than the ones that had been used before. So the idea was to try to see some dim planets that had escaped the detection previously.

and there was a colleague of mine that did the same for another instrument having a look at a comparable amount of stars so in the end of this after looking at maybe 1000 stars and thousands of images and after betting out thousands of background star contaminants we found one planet that was this planet and so I think that this

Hehehehe.

is

you

a good a good way to convey how much time it takes from time to time to get to a discovery. So that's why

I love that.

it's my object.

I... I love the morale that

That's a good one.

hard work still pay off.

Yes.

Yeah, it always does.

Thank you, that's been a really fantastic parallel. Vito, thank you for helping us understand what it really takes to see another world directly.

thank you very much for having me. It was really a pleasure to be here and to chat with you.

good, I'm glad you had a good time, because I've really enjoyed it. It's been very insightful. It was a really, really good chat. And of course, we want to say thank you to everyone listening. Please join us next time on Growing Worlds as we explore another corner of the universe and the people bringing it into view.

As a quick postscript. Since we recorded this episode, astronomers have announced the discovery of a third planet in the Beta Pictoris system, which is Beta Pictoris D, which is a perfect reminder of how fast this field moves.