#EP4: The Solar System

Mikkel:

Hello and welcome to Big Ideas Only. And this is a podcast brought to you by Montanus, which is a company where we specialize in producing high quality content for marketing departments in high tech companies. And I’m your host, I’m Mikkel Svold, and in this episode, we are back in space, but not as far as last time where we talked about far away galaxies and black holes. Because, I feel like we’ve barely scratched upon the surface of our own solar system, which is obviously a bit weird because that’s a bit closer. So today we are going to talk about our closest neighbors. I said in the beginning, actually I said nine planets, but that was wrong, I guess. So the eight planets that gravitate around the sun and all the other things that are in the solar system, and that is not also in the solar system. This is going to be super exciting. And to answer these questions, I’ve invited our expert for today, Mads Fredslund Andersen and into the studio. Welcome Mads.

Mads:

Thank you.

Mikkel:

And Mads, you’re a telescope and satellite manager at the department of physics and astronomy at Aarhus University in Denmark. Did I get that right?

Mads:

Yes.

Mikkel:

Perfect. So I think, we should start out by just kind of getting an idea of what you actually do as a telescope and satellite manager. What does that mean?

Mads:

We often have very different titles and they’re not saying too much of what we actually do. So what I mainly do during day is that I’m ensuring that we have telescopes around the world, one in Tenerife, one in China and three in Australia and some others on the way. And I’m trying to make sure that these are operating as good as possible.

Mikkel:

And when you say, “We”, is that Aarhus University? Who is that “We”?

Mads:

It’s Aarhus University and collaborator. So, we have partners around the world. So that’s for the telescopes where I have been a software developer, also technical engineer, you could say. But some of the telescopes are running robotic. That means that we actually don’t do much on the daily operation if things are going smoothly. But if there’s problems or if there’s upgrades, if there’s stuff we want to add or take away from how we operate it, it’s mainly me who does it. And then we have the satellites. So I work on many different projects. For the satellites we have, for instance, a student cube satellite that will be launched in a few years time.

Mikkel:

Is that a full size satellite or is that a micro-satellite? Because I know Denmark kind of specialize into these micro satellites.

Mads:

It’s a small satellite. As it is right now, it’s not fully confirmed the design and structure, but it’s 10 x 10 x 30 centimeters.

Mikkel:

And so it’s quite small.

Mads:

It’s quite small.

Mikkel:

What can you do with that?

Mads:

Still, we are very ambitious with this mission. It’s students who came up with ideas of what we could do, and we could select among the ideas that they proposed. And it’s now a collaboration with bioscience, where we want to photograph image, well, do images of areas in Greenland, where we can then study climate changes just from the images that could be the melting of ice and glaciers or the reflectiveness of the eyes that tell us a bit about if there’s new snow and if it’s old and so on.

Mikkel:

The satellites that you work with, are they mainly pointing towards earth or are they pointing out in space?

Mads:

This one is pointing towards earth because it’s a bit easier. That’s my take on it. If we want to point to stars and do a scientific measurements of stars, then we have to be very steady with the satellites. So we will have to have extra things on it and it grows more expensive and so on. So it takes a bit more effort to build a satellite that can study stars.

Mikkel:

And you say that it needs to be more steady, but that’s because, like when you take a binocular and you look at something close by, it’s easier to obviously get it within sight.

Mads:

But that’s actually a very good comparison because if you want to… I go hunting sometimes if you want to hit something, you also want your rifle and your binocular very steady. So if you are focusing on something that is far away, you probably have difficulties holding it by hand. So you would lean up against something. It’s actually the same with the satellite, you want to have a very steady look at it.

Mikkel:

And the further away is the less movement.

Mads:

Exactly.

Mikkel:

It’s like when you play golf, basically when I play golf, I always… I’m not good at golf. So, you’re in satellites and telescopes and are these two things very separated or do they also combine as a common concept?

Mads:

Well, to me, it combines because we also work with large NASA missions, satellite missions, there we mostly just get the data, but the philosophy of how we want to observe stars can be translated from telescopes to satellites. And they can, you could say join forces, so we can use that. We are observing from space with the satellite in combination with telescopes. So it does combine how we do the project management, you could say, is also fairly similar. So there are few different things, but how the projects develop, are the same.

Mikkel:

Now, let’s try, we have some kind of understanding of what you do, I guess. And now let’s try to come back to today’s topic because actually in the next episode, we’re going to talk about more into depth with satellites and telescopes and satellite telescopes and all that. But for today, we want to talk about the solar system. And I think maybe, my first question is basically what is the solar system? Because we’ve talked about it at the office here before you arrived and it’s always depicted as this closed entity. But what is it actually and how big is it?

Mads:

How big it is, is actually-

Mikkel:

Where’s the border?

Mads:

… strange, not a strange question. It’s an obvious question, but it’s not very easy to answer because we on earth are 150 million kilometers away from the sun. That’s a huge distance and we are actually close to the sun. So the borders are so far away that we can’t really observe them with telescopes nowadays. So there’s beyond Pluto and the furthest dwarf planets there’s-

Mikkel:

So that was a ninth planet for those of you who care. So it’s not a planet anymore. Pluto.

Mads:

But there we have asteroid belts and also we have something called the Oort cloud, which is a place where there’s a junkyard. You could say leftovers from the early solar system and stuff that didn’t get picked up by planets or didn’t fall into the sun. So there’s a lot. And we actually don’t know really how much there is, but it could extend far beyond what we will ever observe. And we might-

Mikkel:

Why can’t we observe this? Because we can observe stars that are billions of light years away.

Mads:

Yes. But they shine light. This stuff, like the planets, don’t shine much by themselves. So it’s only reflecting the solar light and therefore we can’t observe if it’s… You can’t go and see Pluto with your naked eye in the sky.

Mikkel:

Because it’s too dark.

Mads:

Because it’s too far away. So it doesn’t reflect much light.

Mikkel:

And that way. So from here on earth. Standing here on earth.

Mads:

So that’s why we sent these probes that do fly by and close encounter with these to understand and check what’s going on there. But far beyond Pluto, there’s still a lot of stuff. So we can’t really see it.

Mikkel:

And then how do you define whether it’s in the solar system or whether it’s outside the solar system, this, what you call it Oort cloud with the T, Oort cloud?

Mads:

Yeah. Well, one way of thinking is that it’s a gravitational bound to the sun. So it’s in orbit around the sun. That’s one way, but the gravitational pull is set to extend so far away that it’s actually halfway in between our closest neighbor star, which is four light years away proxima centauri. So, that’s huge. There’s also some other definition of where the borders is, where the radiation from the sun matches the amount of cosmic radiation. That’s usually what is said to be the boundaries of the solar system, but still you can have stuff that is bound to the sun by gravity.

Mikkel:

Even though it’s further out?

Mads:

Yeah. So it’s a fairly vague way of defining where it is.

Mikkel:

But that also means basically that all the posters that we’ve seen with the planets on, it’s a bit misleading, I guess? Or I think it’s misleading because it does actually somehow symbolize or show that it’s a closed system that ends by the eighth planet. And then…

Mads:

That’s not true, but it’s of course for us, the most interesting part, it’s what’s closest and we haven’t discovered much further out either. So, you can also see it as, as our picture of how it is, because we don’t know what’s beyond the poster.

Mikkel:

And now you said that the border, I’m going to call it the border of the solar system, is defined by either the gravitational pull of the sun versus the gravitational pull of the next sun, which is proxima centauri… Is that my… Something says as sound. Well, that’s just my computer I think, anyway. So, that’s one way of defining it or the radiation, but how do you measure the radiation out there? How do you know? Because the gravitational pull, I guess, that you can kind of calculate. Can you calculate radiation as well?

Mads:

No. Well, you can approximately calculate it, but it’s actually changing. So it’s changing with the solar cycle and other stuff. So we have these very early missions, the Voyager 1 and 2 and Pioneer 10 and 11, I think a new horizon that is traveling away from the sun and the first ones, Voyager are already has-

Mikkel:

It’s a really old one, isn’t it?

Mads:

Yeah. That was in the… I can’t remember if it was seventies or even sixties. Something seventies.

Mikkel:

Yeah.

Mads:

But they have passed this radiation zone so they could measure where it was and they didn’t arrive to that at the same time. So it was at a different distance from the sun when they arrived to this. So, it changes a bit, depending on- That’s one of the reasons why it’s not that very easy to say where the border is, because it depends on the definition.

Mikkel:

One thing we did also talk about before the episode was when you’re not counting the planets and you’re not counting this oort cloud, what is in space? Is it the same, like is space itself? Is that the same a couple of 100 kilometers out from earth? Is that the same material or whatever you call it non-material, I guess. As a 100 light years away, is that the same space?

Mads:

Yes. It’s very empty.

Mikkel:

It’s just a big nothing.

Mads:

It’s pretty much big nothing.

Mikkel:

That is very fascinating. Isn’t it?

Mads:

There’s of course, light from stars and cosmic radiation and so on, but there’s really not much. It’s really empty.

Mikkel:

I think I find that quite fascinating that we can explore something that is relatively close or very close in space terms, I guess, very close. And then it’s the same as basically everywhere else.

Mads:

That’s how we understand it, at least.

Mikkel:

I think that I find that very fascinating. And I want to talk about also, what do you think from looking at the solar system, what is the most, why is that interesting for you to look at what? What is interesting about the solar system?

Mads:

Well, the main thing is that it’s very close. Everything in the solar system compared to other stellar systems, star systems is very close. So we can study. We can send these mission that will actually go and investigate where we can do, like on Mars, where we can have samples, do samples, and check stuff, check our theories in much more detail than we can around other stars. So, and of course, it’s the basic everything, all the theories we develop and both about the sun or about how the solar system came to be in the first place, comes from our visual observations of how the solar system is that we can then go and check on other systems. When we started in 1995, finding other planets around other stars. But before then, we actually didn’t know if the solar system was unique, was one of a kind, or if it was a common system.

Mikkel:

And is it a common system?

Mads:

Yeah, it’s not too strange. The sun is a very common star and the size of the planets. And we know that most stars have planets and more than one. So it’s not that special, sadly.

Mikkel:

That’s kind of sad. But is there something that is different from the sun or the solar system in terms of what planets are there compared to what we know from other systems?

Mads:

Well, how-

Mikkel:

Obviously we have life on one of them. And we don’t actually know whether other…

Mads:

Yeah, not yet.

Mikkel:

Not Yet.

Mads:

Before we started up finding planets around other stars, we had a theory of how the solar system came to be and why we had four rocky planets closer to the sun and gas planets in more distant from the sun, which is because you could have ice on solid form in the outer regions where you could then build up bigger planets that could hold an atmosphere like the gas giants have.

Mikkel:

But are they still with solid ice?

Mads:

The core is so com compact that it’s maybe not solid ice as what you put in your drinks here, but it’s on a different form, but it has a lot of the components.

Mikkel:

But they are solid though.

Mads:

Actually, it is interesting, you ask, because it’s not easy to check how we can’t send a space probe into one of these planets and then take a sample and tell us so it’s theories. But there might be some sort of solid surface beneath the atmosphere, but it’s getting very compressed. So it’s different kinds of surface than we know from the earth, for instance.

Mikkel:

Actually, I know this is a kind of a segway, but one of the things that baffled me quite a lot is, how do we know what’s inside earth? Because we’ve only dug worth a 100 meters into earth anyway, or a few kilometers maybe. But how do we know what’s inside?

Mads:

We actually, so we come with-

Mikkel:

Kind of the same problem, isn’t it?

Mads:

And it’s actually a good point because some of the theories of what’s inside comes from earthquakes. These earthquakes start shaking the whole earth. And depending on what’s inside, the waves that are being excited will tell us a bit of, so it will travel differently-

Mikkel:

Sound waves? So what kind of sound waves?

Mads:

Inside the earth. So it’s maybe a different sound, but it propagates as sound waves, but it’s in a different material. And depending on the material and the composition, it will then move differently.

Mikkel:

And then?

Mads:

That you can measure. And then-

Mikkel:

In the pictures that I’ve seen where earth is cut in half and you can kind of see the fireball in the middle and all these layers, how do you know that there are layers? That is not just one big the same?

Mads:

So, that’s… I’m not a geologist, so I don’t know too much about it, but it’s from these waves that you could measure and how deep they go and so on. And if you can measure that they change in structure, depending on how deeply they went, you can see something is going on from this depth and so on. And then, we are expecting this liquid core because we have to have something that can rotate and generate our magnetic field. So there are theories of how the earth composition is based on what we can measure and what we can then come up with of ideas.

Mikkel:

I’m just going to try to kill this sound that keeps coming up. And now this is how we know something about what’s inside earth or have theories about that. But you say that we measure that by basically listening to sound waves. So looking at sound waves and I guess a lot of other tools as well, but then how do you do that on planets outside earth? How do you then know what’s inside? Because as you said, you can’t send a probe. And I guess you can’t listen to sound waves as well.

Mads:

Good question. And actually, even objects, other planets in the solar system, we don’t know much about. So we have theories of what has to be inside based on how we can measure their mass and their sizes and so on. So we can come up with a rough estimate of how they are supposed to be. But not many have actually tried measuring what’s inside and on Mars, I know there’s a seismograph. So what they try to do the same on Mars they do on Earth, measuring these waves to tell what’s-

Mikkel:

They actually put a seismograph on Mars.

Mads:

I’m not sure. Maybe they’re also did it on Venus. I’m not sure.

Mikkel:

That’s another question. Why is it important to know what’s inside the planet? I guess it’s important to know what’s in the outer layer, because if there’s a water or something, blah, blah, blah. But why is it important to know what the core is? There’s nothing in there?

Mads:

There’s a lot of what I do, which is just nice to know. So many things is just, I mean, our perception of the universe, it’s mostly just nice to know. So we want to build a better and better understanding of the whole universe and understanding our neighborhood in the first place is a good starting point.

Mikkel:

Why do we want to understand the universe?

Mads:

Well, I find it interesting at least. And I think since you’re doing these podcast, I think you do as well.

Mikkel:

That’s true. True point taken. And I’m just trying to provoke a little bit. No, I think I often find that like basic research is the most interesting, it’s because it’s also where you can really leap because you really don’t know a lot. So even small details, they’ll kind of lift you. To a new understanding of a lot. You just briefly said or mentioned how the solar system has come to be. How did it, actually?

Mads:

I didn’t say much. I-

Mikkel:

You just mentioned and I noted it. I was like, I got to ask for this. So how did it come to be?

Mads:

So before the solar system was even there, there was a gas cloud, that’s the common theory, a gas cloud that got perturbed by something, which meant that you could have contractions in some places and less matter in some other places. And then gravity started to kick in and made more stuff fall towards a center. And this made the gas cloud start rotating. And during this project matter-

Mikkel:

Why does that happen? The rotation, that’s not obvious to me.

Mads:

No, it’s and I can’t really remember if it’s momentum conservation or something like that. So you have a physical explanation of why that has to. And then the stuff felling towards the center and it could combine to bigger grains of dust or ice because mostly it’s hydrogen and helium that the whole universe consists of. And also the starting point for the solar system. And as more and more built up, of course, you got the star and the center, the sun, but other stuff would then rotate so quickly that it could like the moon around earth, it would, or the earth around the sun, it would not fall into but fall just in the right speed that it would match the gravitational pull and that-

Mikkel:

So the forces of the rotation around, like when you spin a wheel around, so that… Well, I don’t know what that’s called in English, but the force of going around equals out the gravitation of the sun.

Mads:

So we-

Mikkel:

The outward pull equals the inward pull.

Mads:

Yeah. And some stuff piled up and made planets and did never fall into the sun, but most of the stuff it’s 99.9% of the whole material in the solar system is in the sun. So, but the rest, which is not a lot, but it’s still the planets and the comets asteroids, moons, et cetera. But that’s our theory of how it started, but these theories, of course, we cannot go back in time to check it. So what we do is checking against exo planets around other stars and seeing if we can see similarities of very early planetary systems there that resembles what we thought was.

Mikkel:

And how do you know it’s an early planetary system when you look out?

Mads:

There are some ways of measuring age, for instance, if we can measure the amount of hydrogen that has turned to helium, so the fractional difference in the star. Then we can say something about how much time it has taken for it to fusion these hydrogen into helium.

Mikkel:

That a bit of a sidetrack I can hear, but I was wondering, now, looking from earth and being a bit selfish about it, how does the rest of the solar system kind of keep earth? Or how does that… because I know that some of the plans, they kind of protect earth, but how does that work?

Mads:

So Jupiter, the largest of the planets in the solar system, is somehow protecting against the inward coming asteroids and comets and so on because its gravity is much bigger than earth for instance. So we can diverge stuff. But the main protection is coming maybe from the way it’s, as we said in the early part, there’s not much. So the only stuff that comes in is small dust grains that makes the meteors we see on the sky and some are a bit bigger. They will not be too damaging. Then we have, of course, the cosmic radiation where our atmosphere protects us. And there’s also the solar wind and particles from the sun that we need to protection from. So we that we have to put on sunscreens because the UV from the sun can be damaging. And there we have the atmosphere that protect us. But the planets is mostly to redirect larger object.

Mikkel:

And does that mean that the planets rotate in the same, not the same pace, but they rotate like next to each other parallel to each other because otherwise we would be at one side of the sun and Jupiter will be at the other side of the sun

Mads:

That will happen.

Mikkel:

Okay.

Mads:

So we are not holding hands-

Mikkel:

No.

Mads:

… in the solar system, we travel at different. So, eh, for the earth, it takes one year to travel around the sun. For Venus and Mercury, it takes less. For the outer planets, it takes longer. So it’s… We will catch up on the outer planets and the inner planets will go around faster than we do.

Mikkel:

That’s kind of interesting. I think, now we’ve established kind of, quite a lot about the solar system now I think, and now I think just our time is flying also. I can see but just before we end, I want to kind of touch upon what kind of tools do we use today in order to understand the solar system. So we started out by talking about telescope and satellites, but how does that help you, basically? Is telescope, is that just a big pair of binoculars or?

Mads:

In principle, it is. But in the solar system, things are so close that for doing, of course early on, we did use binocular also to understand our solar system. Now it’s mainly sending missions to do deep investigation of several planets. So we have had missions to almost all the planets, not all of them we have touched ground, but because of, for instance, the gas giants, we can’t.

Mikkel:

There’s no ground.

Mads:

But we have had dedicated missions to go to almost all of them. Some of them were flybys where you could photograph and do some simple measurements, are not necessarily simple, but some measurements from the probe. But others, for instance, on Mars, we send a lot, these Mars rovers to do, take into the dirt and try several, also sending to several different places on mass surface to see how it has evolved. You can study by studying what you see and what you can measure. You can tell a story of how Mars was in the past as well. So that will tell us a lot about how the solar system has developed through our time.

Mikkel:

I was just… A question just sprung to mind, are we absolutely certain that there are only eight planets? Or could we also have like not found one yet?

Mads:

It’s actually one of the reasons why Pluto was sadly degraded to being a planet. The dwarf planet was that we started finding new objects that were similar in size to Pluto further away. So we would then not… Everyone was taught, we had nine planets, but then the whole story has had to change. And we didn’t know if it would have to change once or maybe a number of times. And we couldn’t really see how many planets we would then find further on. So there were a new definition and the definition was that, of course it had to be in orbit around the sun. It had to be round by gravity. It, and it had to not produce light. So it could not fuse hydrogen to helium in its core. And then it had to have cleaned its orbit. And that’s the one-

Mikkel:

What does that mean?

Mads:

…. that cause Pluto to be degraded because it’s sitting at the edge of the Kuiper belt, which is an asteroid belt just beyond Pluto. So it, and that means that it there’s a lot of stuff there, but in the orbit, it goes, it has a bit of an eccentric orbit. So part of it will go into this Kuiper Belt part just outside. So it hadn’t cleaned away all the material that is in the same area as itself. All the other planets have-

Mikkel:

It’s not a clean path, basically?

Mads:

Yeah. All the other planets have done that. So, and then further on, these extra, eh… extra objects that were found further away were also in the Kuiper belt. So that’s why.

Mikkel:

So, how many dwarf planets have we found?

Mads:

Oh, I actually don’t know the number, but there are-

Mikkel:

So it’s many in other words or-

Mads:

Not many, but there are at least five or six and maybe a few more. There’s only one that is fairly close to us. So that’s in the asteroid belt between Mars and Jupiter, which, which is called Ceres. And then further away at the distance of Pluto and even beyond there’s a few more micro mark-

Mikkel:

Is Ceres, is that smaller than Pluto? Or why do we know Pluto and not Ceres because Ceres is closer.

Mads:

It’s, it’s smaller.

Mikkel:

So I actually just hadn’t seen it at that point.

Mads:

And well, maybe we had, but the redefinition then made it maybe also come up into this group of dwarf planet instead of being just an asteroid.

Mikkel:

That also makes sense. Now our time is actually up, but I want just, the last question is I want know what you’re looking forward to exploring like in the near future, in terms of the solar system. And then afterwards, I want to know where listeners can find out what you do if they want to follow what you do and what you are working on. So what are you looking forward to first?

Mads:

I hope in my lifetime that we will have man missions to Mars. That will be amazing.

Mikkel:

And is that within reach, because now I’m not talking to Elon Musk.

Mads:

I think it is, but it’s of course there’s a lot of politics and so on into that one as well, but I have a feeling that it will happen in my lifetime. So that’s something I really look forward to seeing. Also, there is some of the moons around some of the bigger planets. Jupiter and Saturn has a lot of moons and some of them are ice moons, which would be really interesting to see if there’s any, anything underneath the ice. So missions to those would also be-

Mikkel:

Landing something on those moons. That does sound exciting. And now where can listeners find out more about what you do and follow some of your research if they want to?

Mads:

So I try to keep my webpage on our university webpage fairly updated. So most of the stuff is there.

Mikkel:

Perfect. And we’ll definitely link to that in the show notes. And our time is now up. So Mads Fredslund Andersen, thank you so much for coming.

Mads:

You’re welcome.

Mikkel:

And I look forward to talking to you again. In the next episode, we’ll touch upon the more of the equipment side of exploring the universe. And now to you, dear listener, if you do like this podcast, please help us by subscribing to it. And also of course share it with your friends and family or whoever could be interested and you can find all the links to something we’ve all the stuff that we’ve talked about. You can find links to that in the show notes on our website, which is Montanus.co and that’s C-O without M. So it’s Montanus.co/bigideasonly. And that’s it for now. Thank you so much for listening.