Rebecca: 

This is season one, episode one, of the Meridian, our brand new podcast.  We are coming to you on September 24th 2021 from Lund Observatory, as we are celebrating the Astronomy Day and Night here in Sweden.  

Crossing our local meridian in this episode we have Michiel Lambrechts, a planet formation specialist from Belgium, who first moved to Lund as a PhD student back in 2010 and is now back as a researcher here at Lund Observatory.  

Each episode we also pick one astronomical object to explore in more detail, and this week we will be taking a closer look at something astronomers once referred to as “Le Verrier’s planet”.  More about that later. 

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The intro scene includes background music and 24 high school students saying astronomical words like “Space missions”,  "Solar wind", "The big dipper", "Galactic dynamics", "Gravitational waves", "Exoplanets", "Black holes", "Betelgeuse", "Dark energy", "Near earth asteroids", "Jupiter", "Ground based telescopes" and more.  Slowly it fades to everyone saying “The Meridian”.    

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Nic: 

Hey Rebecca. 

 Rebecca: 

Hi Nick, how are you? 

Nic:  

I'm not too bad how? 

 Rebecca: 

Are you no? I'm alright. I look forward to, you know, have this podcast with you. 

 Nic:  

Yeah, starting out doing the podcast thing, yeah. 

 Rebecca: 

Yeah, do you think we'll have any listeners? 

 Nic:  

Well, OK, let me think if I'm counting so there's my mum and my dad but. 

 Rebecca: 

Yeah, of course in mine as well so. 

 Nic:  

Yeah, but then.  They'll probably listen to it together so that.  I've got a great start. Probably a few of my friends will litsen to it. It my brother. So like I think. A strong five is probably what I'm predicting for this podcast, yes. 

 Rebecca: 

Awesome, well for those of you who are actually listening. Welcome and... yea. 

 Nic:  

One of the really cool things that we're doing this week is Astronomy Day and Night. I don't really know what that is though, can you tell me more about that? 

 Rebecca: 

No sure. So in Swedish it is “astronomins dag och natt” which is hosted by Svenska Astronomisällskapet - the Swedish Astronomy Association they basically gather all astronomy in Sweden, and they had this idea that they wanted it. They dedicated to astronomy. So in Sweden we have this sort of thing that is like celebrating fika things like cinnamon bun day, waffle day. So astronomy day - - and night. 

 Nic:  

Oh oh, so it's like Astronomy Day - and night. 

 Rebecca: 

Exactly exactly. 

 Nic:  

No OK. 

 Rebecca: 

Uhm, so basically we sort of celebrate astronomy by doing astronomical things like star gazing and have lectures and stuff like that and also having a podcast apparently. 

 Nic:  

Yeah, that's fun.  I will say that “fika” was a really a happy surprise when I did come here. 

 Rebecca: 

That is good. 

 Nic:  

Yeah, I really like “fika”.   Pick up that's not the only thing that's going on though, right?  There's also researchers night?  Once again, I have no idea what that is.  Well, do you know? Can you enlighten me? 

 Rebecca: 

Yeah, sure, so it's actually the European researchers night that's also celebrated across Europe.  Every year on the last Friday of September, so it sort of coincides with this Astronomy Day and Night. 

 But this is not only astronomy, it's all research really.  And in Sweden we call it “Forskarfredag”, so universities, science centres and museums are open for like hosting the public with experiments, demonstrations, talks and exhibitions. So there's a lot of stuff going on this weekend and I encourage people to really go out and, you know, indulge in science. 

 Nic:  

Yeah, really you know grab the bull by the horns. And, you know, enjoy it. 

 Rebecca: 

So if you're wondering where you can sort of look at uh, stuff to do, you can either go to forskarfredag.se or also astronominsdag.se for Swedish events. 

 Nic:  

Cool, so you said when launching this podcast as our contribution, but Lund University is also doing a few other things to celebrate these events too. What are some of those? 

 Rebecca: 

Yeah, so for instance. Well, both you and I work in the planetarium that we have here at the university, so that will be open this weekend so you can go and watch space shows in the planetarium. 

 And also Vattenhallen Science Centre where the planetarium is at has his own programme with stuff you can do .  If you're close to Malmö you could go and visit the Tycho Brahe Observatory which is open. 

But you know, mostly the podcast is the most important thing, I think. 

 Nic:  

Yeah, Tycho Brahe was the guy that had his nose cut off in a swordfight? 

 Rebecca: 

Yeah, exactly. He is, or was, a Danish astronomer.  He did a lot of discoveries, actually, one who will talk about in this podcast I think. 

 Nic:  

Well, I look forward to talking about that in the future then. 

 Rebecca: 

Yeah, yeah. 

 Nic:  

It's going to be fun. 

 

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Nic:  

And now I'd like to welcome Michiel Lambrechts, a researcher here at Lund Observatory. Michiel, welcome. Hey, how you going? 

 Michiel: 

Yeah, good a little.  Bit of a chaotic morning. I forgot the bike lock had to go back and forth but now I'm here and yeah, yeah. 

 Nic:  

Yeah, it seems to be going around. I forgot my keys at home as well, so I've been running back and forth to.  I've got a bit of involuntary exercise, but you can't complain about. 

 Michiel: 

That that's right. 

 Nic:  

So how about we get stuck into it? Tell us a bit about yourself. How did you end up here in Lund Observatory? 

 Michiel: 

Yeah, that's like, how far do you want to go back?  Like when I was three years old - I mean actually OK, but I have to go back maybe a little bit to explain how how I ended up here in Sweden. 

I started studying physics back in Antwerp, where where I grew up and after three years I was like I, I thought - I had picked the worst choice of study and I want to do something else. But you know, I had studied for three years physics so I just didn't want to start over all the way again. I just want to sort of continue my studies. So I tried to look for something that was physics, but like as far as possible from physics. 

 And and you know, an option is astronomy - it is actually a distinct field of study.  And then I looked a little bit around and then I had an option to study this in Belgium, but I live in Antwerp, which is close to the Netherlands and one excellent research Institute is Leiden Observatory which is in the Netherlands which is really amazing. It's a really big big observatory, so there's a lots of different things happening. 

So I did my masters in the Netherlands in Leiden, and at the time there was a postdoc there who is Anders Johanssen, who is a professor now here. So you kind of see where I'm going at.  

So I I got there on the first day and they do this really nice thing in Latin where they make all researchers of the institute give a small presentation on what they're working on. And so all these massive students are there as well. So you get introduced to all their, you know, like fields of study, and that's important. 'cause like you're going to do a research project. 

 And I was so lost I had no idea what these people were talking about. 'cause like I had not studied astronomy, I come from physics background and so on. 

Anders Johansen gave a talk there - which she claims is one of the worst talks he has ever given, right?  It was very technical. I do remember it.  He was talking about hydrodynamical simulations and how you could compute very difficult equations, and do something esoteric with it - which which turned out to be on one of the first steps of planet formation.  

But because it was rather technical, it sort of connected with me rather well.  If somebody was talking about galaxies, I would just be like “I’m lost. I don't really know what you're talking about.  I don't understand the research question,.” 

But if you bring it down to something relatively more technical. I was like “yeah, this sounds familiar.  Hydrodynamics, I know a little bit about that.”  

And then I worked with him and we formed a good connection. It was a really cool research project. 

And then in the end he moved to Lund, to Sweden, and then he was... So yeah, that's how I ended up here. It grew very organically in a way. 

 Nic:  

Yeah it's funny you mentioned not liking physics. I actually went through a very similar process when I was doing my bachelors. I mean undergrad. I also did a pure physics degree too.  

I just wondered why do you think astronomy sometimes - well, I don't want to offend any physicists listening to this podcast - but can be more interesting to engage with? 

 Michiel: 

Yeah, that's a that's a very good question. I might exaggerate a little bit - I like scientifically things and so on - but I think astronomy is special in a few ways. One is which I connect strongly to -  specifically in the area that I started - is sort of this idea that you study the origins of things. I mean, it's genesis. It's about how things start off, and that's that's a very... I mean, there's a. There's a really kind of like narrative string to this, not only scientifically. It's like it's really beautiful to know that there is such a fantastic story to the origin of planets or life. I can very strongly relate to those kinds of fields of study. 

So that's one area.  And now about the offending physics parts. We also think it's honestly one of the areas where we as humanity can make most progress in right now, like it's a really special time.   

We have learned about exoplanets only relatively recently, like since the 90s basically, and you know, there's just so much going on right now, and that's...  it's painful to say this, but this is not true in all areas of science.   

There are actually interesting research areas.  Questions that we can solve now – and in other areas where we know we have solved a bunch of questions, but right now we are a little bit stuck. 

One area of strength of a researcher is also to identify - and that's a bit personal it is to identify where you can contribute - and also to see where are the interesting things to do right now. And I do think that's really astronomy, and specifically planets in general, like in the solar system, our planet, and planets like Earth where we live and also their relationship to all the other planets in our Galaxy. 

 Nic:  

Yeah, I think that I completely agree with you. I really like the idea that personally when I'm motivated, and I do my research, is the search for an earth like planet, 'cause I think that once we look and we find something that's very similar to Earth, that's going to open up a lot of questions and also answer a lot of ideas that we have about the universe, or really inform what we kind of know. 

So I resonate with the idea that it's personally motivating to keep looking through and looking into astronomy as well. But let me pull back a little bit to planet formation. 

 So you're a planet formation expert and use simulations to do that. So yes, what do we know so far about how planets form? 

 Michiel: 

Yeah, that's a very big question. In a way, do we know about anything? But like, I think we've learned recently three important, let's say observational - I don't want to say facts but :  Like how we interpret the observational records, so to say. 

And that is that Planet formation appears to be fast, and I'll try to explain what that means, it is a very efficient process, and I will also get back to what that exactly means, and finally there is also something which we are not often confronted with so often in astronomy.  That is that it leads to very diverse outcome, so that's like the third component.  

I'll try to back up now and explain each of these elements and how we try to work from there to make it a scenario.  A descriptive story of how we think plans form.  

So the first thing is that something that we learn now is that transformation is relatively fast.  Of course I'm talking here about astronomical terms, and it turns out that, like I would say, the bulk of planets form in a few million years, that's actually pretty fast, and it has to do with that during the earliest stages of star formation, there's a specific period where stars are surrounded with a disc of gas, that ultimately ends up in the stars. 

It's the same type of gas and dust particles - actually tiny fraction only like a percent of all that mass that is in this disc around the star is in dust.  It's not a bad name in the sense like. It's like tiny small stuff. I'm talking about millimetre scale kind of really tiny grains. 

 Nic:  

So it is not like dust you find in on a shelf after things? Or is it? 

 Michiel: 

No, although there is some analogy to the idea that you find is kind of fluffy fractal dust bunnies under your bed, and it has some connexion to this actually.  Also, it's probably not really very strongly nucleated hard spheres, but it's more fluffy stuff. It's a little bit. 

 Nic:  

So it's like grains and stuff basically. 

Michiel: 

Yeah. Somewhere in between sand and something that's more fluffy, I would say.  Yeah,  so there is very specific conditions around stars very early during their formation more or less and and that's that's when we think the bulk of the planets form. 

That's actually a relatively new thought.  We thought planets could form over hundreds of millions of years of time, but we slowly have come to the conclusion that many of these planets and the bulk of their mass must have like collected during this disc phase, making the process 10 times faster than we previously thought.  More or less. 

So we're looking for something that is also efficient in another way. It's not only fast, only these very few million years we can form these planets, it's also efficient because we now are starting to understand how much mass is actually in those protoplanetary discs. That's what we call these disks surrounding stars.   And it's not that much. It's like 100 earth masses of solids and you may think “a 100 Earths! that's a lot!”, but if you sort of calculate how much mass eventually of those hundred earth masses that you start out with really ends up in planets, it's around 10%, ten to fifty percent,  maybe even like half. I mean, that's actually pretty efficient.  

A fraction of it is lost in the process, it drifts into the star. Some of it gets locked into small say 100-kilometre sized objects that then get scattered out.   

So there are various ways when stuff does not end up in plans, but actually the bulk of it, or at least a significant fraction, gets into planets. That's also somewhat of a surprise if you study this in more depth, you find that this loss processes are actually very efficient, so you would actually expect to lose much more.   

A then the obvious thing which we learned from exoplanets is that for a long time you could have gone away and said,“oh, you know, like maybe the solar system is super rare” and then after a while, we started discovering exoplanets and the first type of planets we discovered were hot Jupiters, which is all these Jupiter-like planets like we have in the solar system, but placed very close to their host star. 

On orbits like 10 days or something. Very fast they go round.  They're very rare, these type of planets, but they clearly showed that there were other types of planets on different orbits around other stars, but you could be like “Oh yeah, but they're very rare.  You know this is just like a freak of nature, an accident.  Most of the time, maybe, they look like the solar system.” 

But right now, which I think is just like it's one of these things that just continuously keeps amazing me, is that we are pretty certain that around 30 to 50% of all solar-like stars host super-Earths.  And Super Earths are planets that are sort of in between Neptune in the Earth.  So the type of class of plants we don't even have in the solar system.  

They are few Earth masses in size, let’s say 8 or so, and bit bigger than the than the Earth. Let's say they have two Earth radii instead of just one Earth radii. 

So these planets are just out there and we do not have them in the solar system. We do not know anything remotely about these plants in a way - only that they exist. They're out there and extremely common, and we do not know why we don't have such an equivalent planet in our solar system, because there are some very short orbits, they're basically in orbits interior to the orbit of Mercury, often.  So very close to their stars. 

They're very big. We don't understand where they well. We sort of, well we are starting to understand where they come from, but like but that was a big surprise and it showed that the solar system in a way is relatively rare. 

I think also our understanding of Jupiter like planets which, you know, for a while we could have thought maybe every star has a Jupiter like planet – but we now know it's probably around 10% or so.  

So only one out of 10 stars has a Jupiter like planet. So like, definitely, solar systems, in a way are relatively rare, but then you sort of start trying to figure out “OK, but why? Why does it look that way? How can things form so fast and with this type of efficiency in these protoplanetary discs and lead to such a diverse outcome? “ 

So these are like the type of questions I, of course in a more technical way, try to address. 

Nic: 

Yeah,. So you said super-Earths have a tendency to form around Sun like stars. Obviously there is a spectrum of different stars that exist.  Does the type of star affect planet formation process? Like maybe the matter that is in the disc, or is there any other kind of things that you need to consider when planets are forming? 

Michiel: 

Yeah, that's interesting. So we are obviously always very interested in solar like stars. So stars like our sun. A type of star we understand quite well.   But but for various reasons, they're hard to find, and there's another type of star which is very common, which means also often like a bit closer to us.  So for detectability reasons it's actually easier to look around small stars. 

The argument is not so complicated, in a way, it's basically if you look at a small star and you have another planet passing in front of it, which is basically one of the main ways we find planets, you fractionally block more light of a small star than a huge star.  

Compared to a huge star you would just be like a little tiny black blip moving in front of the star while if it is a tiny star, you basically book out of all the light.  You get a very big light dip and that makes it easy to discover. 

 Nic:  

Takes up more area basically.  

 Michiel: 

Exactly. And so these small stars are very interesting for that reason, so that we can study them quite well. And it turns out that they are extremely, uh, rich in planets, which is already surprising. 'cause you know, there's tiny stars which had tinier, or smaller, protoplanetary discs around them, so you could have thought  “Well, maybe plants are not so common around those”, but it doesn't turn out to be true.  

Actually, you find a lot of Earth like planets around these small stars.  So they're actually remarkably efficient - same word again - in forming these small small planets around stars.  

I just have to do a shout out to Trappist.   Trappist one is a very well known planetary system around and M-dwarf, which is one of these very tiny stars.   

It's just a tenth of the mass of the sun. It hosts a whole bunch of planets we've studied in great depth.  And they yeah, they really host a series of Earth like planets.  I just want to do the shout out because I'm from Belgium and the guy who found it is a researcher from Belgium. Michaël Gillon. 

Nic:  

Maybe we can put him on the podcast at some point. 

 Michiel: 

That would be amazing. Yeah, it's an extremely important discovery. 'cause like it's basically our  Rosetta Stone to study planetary systems. 

It's easy to find single planets, but not systems where you have access to a whole bunch of plants at the same time.  You can do comparative studies between different types of planets. That's really very important, and specifically now for the system where we have the strongest constraints on the composition of these planets, which seem to be incredibly Earth-like, right? Yeah, so rocky planets. 

 Nic:  

Yeah, so it's more of an interesting question:  Have you ever, or do you known anyone that's able to simulate a solar system?  With four terrestrials closer in and four gas giants out the back. 

 Michiel: 

Yeah, I mean yeah, obviously a large part of our study is, yeah.  We sort of divide it.  A part of our studies is trying to understand the diversity of exoplanets. But the other part of it is - and I also split my time between doing two things - is trying to understand the origin, specifically, of our own solar system. 

Which is of course special because it's where we are.  But it's also special in the way that we have a whole different way of studying our own solar system compared to exoplanets. Obviously, exoplanets around other stars.  Maybe sometime, maybe in the future. Far, far far future we can go there, but right now we can only do remote studies. 

But of course we can go to Mars. And send robots there and do stuff. So the other way of looking at it, we could say you are more constrained. You have more information. 

And then that means also you have to be a bit more precise in the way you study it. So while you can get away with, say, a relatively crude study to understand some type of remote exoplanet system where you don't know that much about it anyway, for solar system studies you really need to be specific. Do kind of detailed studies.   

So in answer to your question, to sort of say, do we have some sort of super simulation that reproduces everything we know about the solar system?  We certain most certainly do not.  And there are many big big big open questions in understanding the solar system, but we do have, I would say, fractionated parts of study that we know quite well.  

We know relatively well - or we have an attractive consistent scenario with the sort of evolution of the solar system.  

After these protoplanetary disc disappear, so after these few million years where the bulk of the plant formation happens, so we kind of understand there must have been a giant plant instability that basically shaped the architecture of our solar system as we see it right now.  

So these are studies that are mainly focused on understanding the gravitational interactions between the planets almost as they are now, but sort of going back in time and understanding how things could evolve, like as we see them now, studying the interaction between planets, but also the minor bodies in the solar system play big role. 

And then we also try to understand fully specifically things in the solar system about the fairly earlier phase that things are a bit murkier. This is a really active type of research and one area there is very interesting .  There is of course that we have a strong record about the composition of planets. We know the composition of the Earth very well, but we also know what Mars looks like. 

We have meteorites that tell us about the asteroid belt and so on, so then the understanding composition of planets and their differences,  it's something we don't really have an equivalent to in the exoplanet research so far. 

Nic:  

OK, cool, so that's really interesting.  What about your work specifically?  What are you working on at this very moment? 

 Michiel: 

Broadly I'm very interested in understanding the root cause - the roots behind this diversity observed in different type of exoplanet systems. 

Specifically, I kind of want to know if protoplanetary discs -We are starting to learn more about them and they most certainly don't look all alike right? So we can study them and we can understand the distribution of dust in those discs.  And for example, some significant fraction of those discs have rings in them, like areas where low dust is concentrated. 

And then an area where there's just nothing. And then there's another ring where it's a lot of dust, so they're like they show kind of all kinds of different shapes, and some of them are very big, some of them very small. 

They don't all look the same. It's unclear whether they are inherently diverse, so they're just really all very different or that they actually represent different evolutionary stages because we don't always know how old these disks are, so we sometimes observe one and we can't like, say, order them in a time sequence correctly. 

So we just have snapshots, random snapshots. It's like you have a movie and you would like cut out different pieces and then just like all move them in a big bunch and then just randomly draw little scenes here and there. And you have to figure out if they're different movies or is it the same movie? It's a mess.  I don’t know how to order it.  It’s a bit like that. 

And I just really want to understand if there's any inherent diversity in protoplanetary disks that also is reflected to exoplanets, and specifically, the thing that I've been working on for quite some time now is to understand if planet formations requires some sort of special conditions in protoplanetary disc to emerge,. 

For example, a study I've done not so long time ago is arguing that if the mass budget in this prosperity disks is large, that you characteristically end up forming these super-Earths - big planets on close orbits that are really cool to say out loud, “super-Earths”, but in a way they´re also kind of annoying 'cause they are not the Earth. 

They're like much bigger, and they're von very short orbits. 

So you keep on making these super Earths in simulations and at the beginning you think that's annoying.  “I kind of want to form the Earth. Why do I keep doing calculations and end up forming Super Earths?” 

But then somebody tells you that like half of all Stars have super-Earths. So then maybe you need something special to form the smaller planets and that might be that its just a smaller mass budget. 

Why is there a smaller mass budget?  Is it because, you know,  inherently there's little mass available or you just sort of less efficient in accessing that mass so you're not accreeting?  You're not collecting mass as efficiently or, for example, it could be that a role Jupiter plays a role there, that it sort of blocks a lot of material from the outer disc of entering the inner disk, and that starves the inner disc and there´s least less material there. 

Nic:  

So for a bit of fun, what kind of astronomical discovery would make you excited? 

 Michiel: 

Yeah, it's a good question. I mean like to be really honest. I think it's only observers who get excited about, typically their own, observation and hope that it single handedly solves all these big mysteries in astronomy. But I would say it is rarely that a single observation really excites me.   

It's a bit depressing to say, but typically what you want is large amounts of data - collective knowledge. 

It's much more as if all these bits are pieces of a puzzle that you're trying to put together, and all these observations give you one piece of the puzzle, right? 

And you know, you´re never excited about one piece of the puzzle.  Unless maybe it's the last one, but we're not there - at all, right? OK, so we're not looking for the last piece of the puzzle. We're like, really, just like looking for - just pieces. 

But OK, I understand that's kind of a boring answer. So, if I would have all the all the, I want to say time in the world, but it's just more about power.  If I could decide. 

One thing that I think would yield immediate results, and is really very important and we could do right now is, I would take like two years on the ALMA radio interferometer.  OK, so that's in the Atacama Desert.  It's this huge array of telescopes that observe in basically millimetre wavelength, so that's actually kind of radio wavelengths. 

It's THE instrument used for pro planted discs.  And most of our observation of protoplanetary discs, I would say - OK, so that's a bit exaggerated – but almost all of it comes from ALMA these days, and it's because this imager is fantastic for this type of studies. 

But unfortunately we are not the only people using these.  It goes to galaxies and so on, so one has to divide the time. It turns out that if you just keep on dividing the time down between different research areas and different groups you often only end up with a few minutes of time on this instrument to observe one of these protoplanetary disks. 

And that's a shame, because we do know if we stare longer at them we learn much more  and we can see much deeper and then we can also start to access much closer to the stars in areas that are much more interesting to study. 

So if I would have all the time in the world, I would just take all nearby star forming regions where they have these protoplanetary disks around - I mean they're limited in number - and I would just observe the hell out of them, in the highest possible resolution and we learn so much. 

I mean it's a limited sample.  You could just do them all. Yeah, that's the exciting part of it. Now we're just doing it in a very drawn out way like iteratively step by step every cycle on this machine we get a few more minutes, so to say. And it goes on and on and on. If I could decide, and be impatient, I would just book the whole thing for my personal profit - and humanities and  everybody else working planet formation. But also just me. 

Nic:  

Yeah, well, maybe one day you will get a lot of time on a telescopeor we'll figure out a way to expand the time that we can observe, but I think it's time to wrap up for now. 

So I just want to say thank you so much for having us on the Meridian.   it's been great listening to your knowledge and he talk about science, and your passion as well. 

Michiel: 

Fun to be here.  Thank you. 

 

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 Rebecca: 

Looking through our telescopes, we can observe and study the universe we live in. We see comments with long tails, spiral galaxies, craters on the moon and much, much more. 

Today we'd like to spend a few minutes taking a closer look at one of the many wonders of the universe. Here's the sisters in the podcast. 

We have Katrin Ros, the editor of the magazine Populär Astronomi.  Welcome Katrin. 

Katrin: 

Thank you Rebecca.  

Rebecca: 

I'm so glad that you can join us in in this podcast and have this section with us. It's going to be so much fun. 

Katrin: 

I'm super happy to be. 

Rebecca: 

Yeah, OK, tell us what has captured your interest today? 

Katrin: 

I think we should talk about the planet Neptune today.  Do you know why?  

Rebecca: 

Please enlighten me.  

Katrin: 

So yesterday, September 23rd, was actually the 175 year anniversary for discovering this planet. 

 Rebecca: 

Oh wow, that's cool. 

Katrin 

Yeah, I know, right?  And the way they discovered it is even cooler I think. 

So it was actually not discovered just by somebody looking out in space and finding something there, but they, with the help of mathematics, they could sort of say they should be there. 

 Rebecca: 

Right? OK, how did they do that? 

Katrin 

Actually they found Uranus first, so the planet is the next furthest out in our solar system, and then they discovered it and they studied it for a while and they looked at how its orbit went, and they sort of started with something off with it. 

It didn't really follow the orbit it should do.  So then because they were very smart and they could calculate things, they sort of thought that there must be something else out there. 

This went on for a while and then in 1845 it was a French mathematician and astronomer Le Verrier...  

 Rebecca: 

Oh, that's where the name came from!  In the beginning of the episode we said it is called a Le Verriers planet. 

Katrin: 

Yeah, that's right.  Yeah, so he then looked at this and he used Newtonian physics which he was really an expert in. And with the help of that he could really like say "yeah, you're right. There must be something out there” and he could even say exactly where it. 

Rebecca: 

Cool, that's so cool. 

Katrin: 

So then he sent a letter to some astronomer, observer astronomer, who then just pointed their telescope and could see it exactly where it was supposed to be. 

Rebecca: 

Oh wow, that's so cool. 'cause you know, like in in school you're like “oh why do I need to do mathematics? It's kind of boring”.  But here's your proof that it works.  And it probably took those astronomers years of work to know where to point it. 

Katrin 

Yeah, I know, I know they had actually really seen a Neptune before.  A long time ago, like in the 1600s, but they didn't know where it was. So you really had to have both mathematics and observations to find it. 

So yeah, if you ever want to find another planet, it's good to study Newtonian physics. 

Rebecca: 

Yeah, but isn't this sort of I don't know how much you know about it;  but there's like Planet 9 that has been proposed.  Isn't that sort of the same thing?  You look at how stuff moves out there and then it's like “oh maybe there should be something more”. 

Katrin: 

Yeah, yeah, exactly. That's sort of the same thing. 

 Rebecca: 

Ah, that's cool, but I guess these days we know a lot about Neptune. It's an icy giant. 

Katrin:  

And it has sort of at least 14 moves, so that's a lot. 

 Rebecca: 

That's a lot, and you know, speaking of moons, the Earth’s moon is sort of a part of the theme for this week or this weekend, which is the Astronomins dag och natt. 

Katrin 

Yes, yes exactly. 

 Rebecca: 

That's very cool. So like, uhm? 

Katrin 

Yeah, so we're going to the moon soon, right? 

Rebecca: 

Oh yeah, we are. We haven't been on the Moon since like the 70s, right or? 

Katrin 

Yeah, something like that. The humans right? But we have had a lot of robotic missions going there all the time, right?  So it's not like we left the Moon behind completely. 

Rebecca: 

OK, yeah, that's true. We have like a lot of these Rovers going around there and stuff. 

And I've also heard that NASA is planning their Artemis project, but we also have this Gateway project with the ISS partners.  

Katrin: 

Yeah, exactly. So that's like a robotic orbiting space station. 

Rebecca: 

That's so cool. 

Katrin: 

And this Artemis programme is also super cool where we're actually planning to send people back to the Moon and maybe we will have a Swedish-American astronaut there. 

Rebecca: 

Ah, you talking about Jessica Meir. 

Katrin 

Yeah, exactly.  She's one of the of the astronauts who are aiming to go there so if she manages she could be like the first woman on the Moon. 

 Rebecca: 

Oh, that's so cool.  For those who don't know, then Jessica Meir is like the first female Swedish, well Swedish/American, astronaut. 

Which I, sort of an aspiring astronaut, think is super cool, I'm a big fan of hers. 

Katrin 

Yeah, that's right. I've heard that you have actually applied to become one of the new ESA astronauts, right? 

 Rebecca: 

Yeah, like fingers crossed that it goes through but they sort of got back like to those of us who applied a couple of weeks ago, saying that OK, not everyone has heard back, but that's because we had so many applicants. They were like 23 000 applicants, so they were like if you haven't heard back because they sort of got back to the people who were not filling their requirements at all, but if you haven't heard back then like no news or good news and I haven't heard back. 

Katrin: 

That's awesome.  So you could still be an astronaut, you could be like the first all the Swedish female astronaut.  Who knows. 

 Rebecca: 

Yeah, exactly. 

Katrin 

So when are you going to hear back? 

Rebecca: 

They say that everyone will hear back like by the end of end or beginning of November. I actually don't remember, but so that's fairly soon. Fingers crossed, but if you sort of pass this first step, you get to actually go to one of their centres and do like a full day of testing like physical capabilities and those kinds of things.  I hope to get through that stage. 

Katrin 

That is so cool. Yeah, it is really cool. I really hope it works out. That would be awesome. 

Rebecca: 

Thank you, but yeah, I hope I get some weird. It would just be a lot of fun and you know.  Otherwise, I just apply again. 

Katrin: 

Yeah, yeah, well good luck with that. 

 Rebecca: 

Thank you and thank you so much, Katrin, for joining us and talking about Neptune and the Moon with us. 

Katrin 

Thank you for having me. 

 Rebecca: 

Yeah, look forward to next week. 

 

---------------------- Scene change with music. 

 Nic:  

This first episode of the first season of the Meridian was hosted by Nicholas Borsato and Rebecca Forsberg.  Our guests today were Michiel Lambrechts and Katrin Ros and our producer was Anna S. Arnadottir.   If you have any comments or questions about the show then feel free to reach out to us via our emails or via the @LundObservatory account on Twitter. 

In our theme at the beginning of the show we could hear members of the 2021 Astronomic Youth Research School, which was held here in Lund back in July.   

The music we have heard is called Twilight and was composed by Stellardrone. 

You can find all of our episodes on www.astro.lu.se/TheMeridian and make sure you tune into next week’s episode, when we will be visited by Josefin Martell from the Department of Geology here at Lund University working on impact craters. 

Thank you for listening.