How to Find an Exoplanet

are all, you know, amateur astronomers. Uh. One of the things I've always thought would be really cool would be to actually make one of those discoveries of an exoplanet. Um. You know, it's it's just an interesting idea of being able to say I have discovered the presence of another body orbiting around a distant star. So it got me to thinking, you know, how hard is that? And um, it turns out it's pretty hard. Well, it's getting easier. I mean it's certainly easier than it was a few

thousand years ago. Yeah. Well a few thousand years ago I'd say it was impossible. Yes, why is that? I mean, why can't we just look up and and see planets all throughout the Milky Way for example. Well, they don't emit electromagnetic radiation the way that stars do. Yeah, well

they might, they might emit some frequencies, they certainly do. Yes, No, that was a very scientifically inaccurate thing for me to say, Um, they don't emit as much, and they don't emit light their own They might get it reflected back from the star and they're going to fade away because they're very far and they're very small, and they're very dim compared to the stars. But I was actually curious when you

think about exo planets. Surely somebody must have guessed at this before we detected they were there, and so who were the first people to actually suggest that there were other planets out there that were different from stars. Well, there's there's a lot of different philosophers who have talked about this, um, even before we got to the heliocentric

model of our solar system. So if you want to go way back, you had a couple of chuckle heads, Aristotle and Epicurus, who were were Yeah, they were just you know, they're they're sitting there, you know, taking their lunch on the edge of giant stone work, you know, the hard hats on their heads. I get a lot of my historical knowledge from the flint stones, so uh,

just roll with me on this. Anyway, they were actually having a debate, and Epicurus said that he believed the universe to be infinite, and therefore it would contain an infinity of worlds within it. By definition, if the universe is completely infinite, then everything is unnumbered. I mean, you have just a countless number of everything's, including other worlds. Um. Now, Aristotle said he believed the Earth was at the center

of the universe and therefore was unique. You can only have one center, and he didn't think that because he was stupid. I mean, that was a thing that made sense to think back then, before we had telescopes and modern astronomical equipment, it really did seem like the Earth was the center of the universe. It didn't seem to move. Oh sure, sure, it seems like you're standing still and

that the sky is moving around you. So therefore, yeah, obviously you're the one who's on the stationary uh rock, and everything else just moves in spheres around you and uh. As it turns out, that was a pretty popular view for a long time. Epicurus is view was not the most widely accepted Aristotles, however, was for quite some time. And um so even with epicurus view of the infinity world type of approach, it didn't necessarily mean that he

thought worlds were orbiting around stars. He just thought that there would be other world olds. There are other worlds than these for my Dark Tower fans out there. Um. But then you get Copernicus coming around in saying, hey, you know what, I think the Earth is going around the Sun, not the Sun and everything else going around the Earth. And there that caused a bit of a debate,

I would say, in philosophical circles. Um. Yeah, And then you get a fellow named Giordano Bruno who back in proposed that other stars might have planets of their own, just like our Sun has planets orbiting it. Uh. There were some people who disagreed with Bruno. They they took issue with what he had to say. It was the Roman Catholic Church at the time, and the way they expressed their dissenting this discending opinion was by burning him at the stake. So Bruno paid for his his belief,

which turned out to be true with his life. Yeah, people were even harsher back than than they are in YouTube comments. Yeah, it's about to say it does bring a little perspective, but you know, figuratively speaking, YouTube commoners

are pretty much doing the same thing to us. But figuratively alright, So at any rate, that was sort of the the If you want to look at the earliest thinkers who were putting forth this idea of other stars having planets orbiting around them, those would be the earliest ones I would point to. But these days we actually have direct evidence of planets orbiting other stars. We don't have to guess anymore. We can actually use the instruments of astronomy we've created to get data that tell us

there must be other planets out there like us. And this isn't just a matter of pure curiosity. It actually bears on many other questions and science and maybe even the future of what happens to the human race. Sure, now, of course, the pure science element does matter a lot, because, as with every question in science, we can never really

know how a piece of information, once gathered, might be used. Yeah, something that we know about astronomy about exceplants may prove useful in the future in ways that we don't imagine right now, even if that just means that we get a better understanding of how our universe works, which you know,

some people dismiss, but that's that's just really cool. The idea that we learn things new things about how planets are formed and how how they uh you know, orbit their stars and what kind of different bodies they can orbit, or or what kind of planets are the most common, like how unusual a situation like Earth is, or how many gas giants there are, or how big or small many planets are. Yeah, yeah, very good questions. The other thing you might want to consider is how about Earth too?

How about Earth too? Well. One thing you might observe looking at us in our environment is that the population of humans on the planet is consistently growing, but the planet is not getting any bigger and its resources are not multiplying. There may come a day when, in order to continue growing, the human species needs to expand beyond the planet Earth, uh well, especially to continue growing, growing in a way that's comfortable and healthy for all of us.

In other words, we have to have another place to go. Yeah, And so you might look at planets in our own solar system and terror forming colonization, or you might look way beyond and say, well, is there possibility we could colonize extra solar planets planets in other solar systems throughout the galaxy? It might be more worthwhile to take a little bit of a road trip to someplace that's a lot more habitable. Yeah, maybe, depending on how fast we can get there. Well, And that's a question I think

we'll look into towards the end of this podcast. But another one of the big questions that exoplanets bear on is the question of astrobiology extraterrestrial life, Right, what other life is out there beyond Earth? Is it Earth like? Is it very different from Earth life? That we we have a sample size of one planet. When it comes to life, we have no way of knowing if what we think of his life as representative of the entire galaxy,

let alone the universe. So this would be a huge thing to be able to look at another planet and determine what are the what's the likelihood of life being found there? Right? I mean, just the discovery of other planets out there in the habitable zones around stars is already bearing on certain things like the question of the Fermi paradox. You've got that Drake equation we talked about. We did a podcast back. If you're not familiar, you can go check that out our podcast on the Drake equation.

But it's the question of why aren't we hearing any signals from alien civilizations? Um, what's the thing that's limiting the number of alien civilizations out there? And it used to be thought that, well, maybe there just aren't enough planets in our galaxy on which alien life could arise. We now know that that variable is smashed. There are tons of planets out there, so we're actually narrowing down

the question. It's got to be one of these other variables limiting the number of aliens that could be talking to us but aren't. And why do we know we need to look at planets? Well, I think we can make a pretty good guess based on physics that we're not going to find life forms in stars, not life as we know it at any rate. Yeah, where we're going to need something more or less Earth temperature. You know, water would need to be in a liquid state at

least at some point during its cycle. Yeah, it's yeah, it's hard to imagine any kind of complex system like a life form existing at a temperature that a star would operate at. Yeah, I wouldn't do well in it. So let's take a look at some actual discoveries of exo planets. I want to know when was the first

exo planet really actually discovered by science? All right, well, if you're looking for the first time someone pointed at at data and said, we can be definitively sure that this is coming from other planets outside of our Solar system. You know, it was just twenty years ago when we saw someone point and say, this is definitive proof that there is at least one, probably multiple planets outside of our own Solar system, and here's the data to prove it.

It was a radio astronomer who discovered it back in and uh he detected two or three planet sized objects in orbit around a pulsar in the Virgo constellation. So not a star but a pulsar, which is the remnants

after a supernova, so kind of interesting. It actually got some people grumbling about how it shouldn't count because the exo planets were in an orbit around the star, but um, uh, the data was from the radio telescopes he was using, and uh he was detecting, uh, the the effects of gravitational force of multiple large bodies upon that pulsar, which was what allowed him to infer that there were planets

or around. Yeah, and we'll talk more about that kind of way of detecting planets in a little bit now. The first discovery of an exo plant that was actually an orbit around a star. Yeah, this dates so just one year later, and it was a pair of Swiss scientists who announced the discovery of a plant somewhere between half the size of Jupiter and two times the size of Jupiter. That's it's actually pretty tiny for for exit planets.

It's also it's also uh, you know, it sounds like a huge range, but really when you're talking about galactic measures. It's so they determined that was an extremely close orbit around its parents star, which was fifty one pegasi, and its year was really really short. It's year lasts four point to earth days, so every every four point two days it orbits its Sun. Feels like it feels like a whole lot of whiplash. To me, how many years old would you? Why did you ask me that question?

I would have I would have actually done the calculations that I thought about it. Um, I'm almost I'm almost. No, I'm not gonna do it. If I try and do the math, that will just come out horribly wrong. Well, anyway, they had discovered the presence of this planet again through indirect observation. They used radial velocity detection, which will also

kind of talk about in a little bit. And soon, because they showed that this method was uh you know, it was a working method, soon the discoveries just started coming pretty quickly. Now, at first, like a lot. If you look back at the history of exoplanet discoveries and you're looking at stuff from the early two thousand's, they'll they'll say, like eight whole planets have been discovered so far. But over the next few years, especially once we started to really know what to look for and we had

access to some pretty incredible tools, Uh, that number exploded. Um. Now. The first DEDICAD exoplanet space mission was the launch of the Corot Space Telescope in two thousand and six, the c O R O T, and it provides a continuous observation of a stellar field for a period of up

to six months at a time. So it just it just keeps its uh, it's I essentially on a specific segment of space and leaves it there for like six months to see, you know, any sort of variation in the brightness of the stars that are in that stellar field, and when it starts to detect variations, it looks for patterns. So if you find a pattern in the variation of the brightness of a star that suggests that something is passing between that star and Earth on a regular basis,

we'll talk more about that too. So those are kind of the early approaches or the early um the early examples of this very young field. Well, I think we should look at some of the most common methods that are used to detect extrasolar planets. Yeah, sure, Well, I think the first one we should mention, though it's certainly not the most common at this point, is simple direct imaging. I think this is what a lot of people would

just guess is happening. You're just taking a picture up in the sky and you see next to a star, there's a little planet, a little dot, and there it is. Yeah. The problem is that that those dots at that distance are saying they're little is being generous, Yeah, that they just the typically don't emit enough light that's detectable at this distance and distinguishable from the star they orbit to see this. This is a problem we have at this point.

It's really hard to directly image planets. There's there's also a lot of glare coming off of well, glare coming off of a nearby stars that's going to obscure direct visualization of planets like that. Yeah, though it has been done. We have card direct images of a few extra so the planets with radio waves and with infrared, I believe.

But there are other methods that are have been used a lot more commonly, and one of the main ones I want to talk about is the radial velocity method is the one I had mentioned earlier with the approach with the radio telescope. Yea so true or false question t r F question for you, And you can't just draw that little thing that could be a T or an F, so we have to come down firm the whole word. Okay, true or false? The Sun is stationary,

the unmoving center of gravity in our solar system. That well, I mean, I know the answer to this, and also it's in our notes, so it would be cheating. But would you would you like me to play along? Play along. I think that's true, Joe. Well, it's true. We do go around the Sun. Except it's false because the Sun is not stationary. Wait, it's both true and false. You tricked me, Because in space it actually isn't the case that a bigger object pulls a smaller object. It's the

case that both objects pull each other. Yeah, the force

of gravity exerts on both, on both masses. Right, So when you have two objects, it may look from one perspective that, say, Jupiter is orbiting the Sun, but in fact, both Jupiter and the Sun are orbiting the center of gravity between Jupiter and the Sun. And because the Sun is so much bigger than Jupiter, the way this typically looks is just that Jupiter is going around the Sun, right, because the Sun's size actually overlaps that edge of the

center of the gravitational Furthermore, I mean the entire Solar system is moving um and our entire galaxy is moving right right, So there are several ways in which the Sun is moving. Yes, but it actually does move in response to the gravity exerted on it by its planets, And an outside observer could look in on this and notice it, especially in response to the big planets like Jupiter and Saturn. The effect is that the sun or the star seems to wobble. Yeah, it actually appears to

be moving in relation to those plants. And if you're far enough out where you can't see the planets but you can see the star, you'll see that the star is wiggling a little bit, since it's doing a little bit of a chimmy. Yeah. Right, So the same is true in other solar systems throughout the galaxy. But how would we detect if a star that's dozens of light years away is just wobbling slightly in response to the gravitational pull of a planet like it would just seem

like it's a pin prick. And how could you ever be sure that what you saw was a wobble and not say the fault of your instrumentation? Right, Well, you can measure it with the Doppler effect. Now we should probably explain what the Doppler effect is. Okay, so you you may remember this from physics class in high school.

Any object emitting waves, which I love objects that emit waves. There, whenever something emits waves, it seems to produce higher frequency waves when it's moving towards you and lower frequency waves when it's moving away from you. And if you just picture the waves in your head, you can kind of see why this is the case. Something coming towards you is compressing the waves as it moves in your direction. Something moving away from you is stretching the waves out

as it moves away. So this would be if you ever hear you know, cars going by you where they're honking the horn. You're exactly right. Yeah, the passing police car is the classic example. The sirens higher pitched as it's coming your direction after it passes by, exactly right. This is also true with light. It's not just now you know, sound is a physical acoustic wave, but electromagnetic radiation the same thing. The same principle applies. Yeah, so

you can have the police radar gun. The police officer can clock the velocity of an approaching or receding vehicle by bouncing radio waves. I think it's usually microwaves off the car, so it shoots the gun, bounces the waves back, and then by calculating the difference between the outgoing waves and the waves coming back, the radar gun can detect the speed of the car. But this also works for

electromagnetic waves produced by distant stars. So as the star wobbles away from us because of another object in the system, the radiation signature changes to a lower frequency, the red shift. You may have heard of this, And then when it wobbles back towards us again, the radiation signature is shifted

up towards the blue frequency, the blue shift. So by studying the pattern of how the star wobbles, astronomers can actually learn a whole lot about the planet that's causing the wobbling, including a pretty good guess at its mass. But there are limitations to this kind of thing because the method depends on the gravitational poll exerted by the planet. It's best at finding relatively high mass planets closely orbiting relatively low mass stars. You remember that gravity is dependent

upon two things. It's depending upon the mass of the objects in question and the distance between them. So the closer and the more massive the objects are, the more detectable this would be. Yeah, So what kind of tools our researchers using to detect this sort of thing? Essentially we're using telescopes and spectrometers. Now, a spectrometer it does is it separates the light that comes from stars into its component colors and then detect the subtle changes even

when those changes are indistinguishable too. We puny mirror mortals, right, so it can detect with high precision the light frequency and how that changes as the star wobbles. In fact, there's another method that basically tracks the same effect, but in a different way. This is called astrometry. This actually dates if you're looking at the earliest of the astrometry, it dates to like nineteenth century. This is much older, and I think generally considered not not as accurate at

this point. It's we we've mostly moved on to the radio velocity and to another one, but interestingly it may come back. Yeah, but I'm sorry I should say what it is. It's a way of looking for the same wobbling of planets visually. Essentially, you just look at where a star is in relation to the other stars around it, and you visually track its movement over long periods of time. As you can guess from the sound of it. That's

hard to do. Yes, that sounds like you would need a really big telescope and a really high res camera in order to work that out. Yeah, I'm sure, I'm sure, photography made this a lot easier than it was before, you know, when you just had to kind of look at it and seeing, yeah, that's that's a half a degree, it's a scoch. But then there's another one where you can try to infer something about planets just by looking

at the star itself. And this is probably the one that's on the rise, the one that just recently got really big, the transit method. Yeah, this is where you're looking at the light that's coming from the star and you're looking for any sort of dimming that would be indicative of a body passing between the Earth and that star.

All right, a little bit like observing a solar eclipse here on Earth, where the moon is passing between you and the sun, right, except on of course, obviously on a much smaller scale because the distance is involved, uh,

and and our perspective. But the idea is that we would use very precise instrumentation to measure the amount of light that's coming from a star and looking for those sort of patterns that you see a one percent dip in the luminosity of a star at certain regular intervals that could be indicative of an an orbiting body going around that start blocking some of the light. Now, obviously

this depends on lots of different factors. The precision of your instrumentation is a big one, but another one is just the alignment of the planet's orbit around that star compared to where we on Earth are. Because despite what most science fiction films would have you believe, space in fact has lots of different ways that you can come at different objects. And you're not always just nos two nose in your spaceship with the other spaceships. Sometimes you're

all catty wumpus with each other. Like, like we said, everything is moving. So if you you know, imagine that you are looking at the star and the planet orbits it in a way where it doesn't pass between the star and Earth, you know, the plants in orbit, uh that from our perspective, it would be like a halo around the star. Well, we're not gonna be able to see that planet because it doesn't pass between the star and us, uh, and it's too dim for us to pick up on on its own. So the transit method

would not work for those kind of planets. So for any system that is in a in that sort of alignment in respect to where we are, that's great, But for all the ones that aren't, we have to use some other methodology. What about gravitational micro lensing. This is another kind of rising in popularity method and it's sort of parallel to this transit method, but instead of looking for a dimming, we're looking for a brightening UM And

let me explain how how the heck that works. UM. So, so what's going on is that we've got two star systems that we're looking at, one distant and one really bloody distant UM. And when the nearer one passes between us and the farther one, the nearer one's gravity bends and magnifies the light that's coming from the farther one like a lens. So the farther star appears to smoothly brighten and fade over a period of a few weeks or a few months UM. And this is pretty nifty

unto itself. So where do exo planets come in? You might ask, Well, if the if the nearer star system contains a planet, that planet's gravity can cause hitches in the brightening and fading pattern, or even cause a sort of lens flare. Almost this type of probably UM and this method is is really read for for finding smaller, potentially Earth sized exo planets um, which in turn is important in our search for extraterrestrial life as we know it.

As we said near the top of the show. Um. However, it's a little bit tough to use this method to tell the exact mass of the extra planet in question, UM. And and that's because okay, so, so researchers can use their observations to determine the ratio of the masses of the planet and its star pretty easily, but they have to make an educated guess about the actual mass of both based on statistical modeling and um any other electromagnetic observations that they can make about the stuff. So, uh,

it's it's imprecise in that way. Interesting. That is interesting. And I want to ask about a weird thing about robe planets. You'll heard about these. Yeah, I love that you kept my note in here, which first of all, they can't touch other plants where they will totally steal

those planets superpowers. Well, okay, hold on a second. Almost all the methods we're talking about here, except the direct imaging, are involving how a plan in it affects our view of a star right, that's how we gathered the data about it. So how can you do so if you have a planet that's floating out there in the middle of interstellar space, which not orbiting a set is definition yes, orbiting the galaxy center directly instead of orbiting a star, can you see it? Is there a way or not

see it? But is there a way you can determine it's there and learn anything about it? Okay, So so rogue planets to to really break it down here, UM are not orbiting a star for for one of several reasons. UM. They could have escaped their stars orbit, either due to the pull of a nearby star or due to their star going red giant perhaps and and pushing its planets out UM. Or they might have formed out in the interstellar dust UM and just didn't have enough mass to

start fusing hydrogen and thus become a star. Or and thank you guys for leaving my joke in here, they might have just rolled really high on dexterity UM. So so they're not So they're not very near um any stars, meaning that hey probably not obscured by light from a star, which is cool UM, but they're probably not illuminated much at all, which does make them tough to see UM, but researchers can use UH telescopic cameras with filters that select for certain segments of the spectrum UM and then

scan darker areas of the sky UH. At that point, redder colors are going to indicate cooler bodies like either brown dwarves, which are similarly formed when clouds. OH. Interstellar stuff don't get dense enough to become stars, although they are way bigger than planets, even like gas giants like Jupiter UM or it could indicate an exoplanet. So have we actually seen any road planets? Thousands have been identified in the last ten years or so, and some researchers

think that there could be billions. In any single given nebula um. There might be a dozen that are less than a hundred light years away from us right now. I just like the whole part where you talked about the scan darker areas of the sky because it made me think that you have to put it through a scanner darkly. Oh yeah, well this is this is the nerdiest entry in our outline. Excellent. I didn't put that

in the notes though, so it was just me being obnoxious. Okay. So, so road planets are really fascinating, especially because we're not entirely sure how they got out there. But they're perhaps less interesting than some solar bound planets because it's less likely that they're going to contain life as we know it. I actually, uh, it would seem like that, but I feel like I've read stuff saying that maybe they could

contain life, like they might be warmer than we would imagine. Speaking, I don't know, no, and I mean I mean space, space is warm. Space is not cold, as we have mentioned on the show before. So I'm just trying to figure out where the energy source would come from. Geothermal you know, like deep see events. Yeah, it's possible. I suppose radiators, it's just what Unfortunately I can't remember where I've read that now, and our WiFi is out so I can't look it up. Yes, technology, um okay, But

so speaking of technology, what what about the future? Um? Where where is this research going? Well? Recently, in our podcast about telescopes, we talked about how some upcoming telescopes might really help in the search for exoplanets, especially stuff like the James Web Space Telescope, and how that might use infrared to teach us a lot about what exoplanets

are out there, and that's really exciting. Sure, but there are also other methods that could be coming up well, and some of them are dependent upon things that we can't necessarily, ever ever say are going to be you know, evident to us, right, like gravitons. That's so you're using your hypothetical particle. Friend. Well, you asked a hypothetical question, you get a hypothetical answer. So I like all my hypothetical friends. They're are the less said about my hypothetical

friends the better? All right? No, No, the reason why I mentioned gravitons is so gravitons, that's that's kind of like our placeholder. Yeah, so you have particles that mediate the other forces of the universe, like electromagnetic force, Um, you have the photon. So gravitons are supposedly the hypothetical particle that we think might mediate the force of gravity. We've never found this particle if it exists, right, we don't. We don't have any way of directly observing that this particle,

if it does exist so far. But you know, it's one of those things that we have kind of to make the math work. I mean, that's that's a simple way of saying it. But in order for us to describe things that are going on, it's a very useful hypothetical particle. But if it is a real particle and we found a way to detect them, than anything that has a gravitational field hypothetically is giving off these gravitons, and so if we could observe them, we could observe

lots of stuff. Yeah, I like to think of it like the scene in The Matrix where Neo is suddenly able to see the entire world as the series of ones and zeros and can actually then manipulate it. We wouldn't be able to necessarily manipulate anything through gravitons, but we might be able, through this kind of detection process, be able to to see the presence of stuff out there that we never would have picked up on before.

It would it would lead to a true explosion of discoveries and would be incredibly useful for things like, you know, detecting asteroids, things that could potentially cause us lots of issues. Now, all of that obviously depends upon a hypothetical particle turning out to be a real thing that we can actually directly observe, and that may very well never be the case. It may always be the case that we only observe the effects of gravity through the actual interaction of masses

in space. It would not be you know, viewing the actual particle, hypothetical or otherwise. So it's a huge If I have a question, please ask it. We're all talking about planets within our own galaxy, the Milky Way, are our little neighborhood of the universe. Yeah, I just want to make sure I'm correct in assuming that it would be absolute madness to think we could detect something as small as a planet in another galaxy, right right? No, no, no,

that is not absolute madness. Is it really possible that somebody might be able to detect a planet in, say, the closest galaxy to us. Some researchers think that we already have whoa tell me about it? WHOA? Indeed? Um? Okay, So, remember when I was talking about gravitational micro lensing. Some scientists out of the University of Zurich in Switzerland think it's possible to use the same method to detect planets in Andromeda, being our nearest galactic neighbor. But you know,

still being more than two million light years away. Um, other galaxies. I mean, just so y'all know, I mean you might not have a sense of cosmic scale. That's so far away. It's not close enough, way way out. I mean you might think it's a real walk to get down to the chemist, but that's just peanuts compared to space. Yeah, it's way too far away for us to even pick out individual stars, um, even with our

most impressive telescopes. So instead of looking at stars here, they're looking at pixels, each of which contain the light from several stars. And and they can they can use that same method of brightening to try to determine when weird stuff is happening. You mean, the gravitational micro lens. The gravitational micro lensing, right, So, so something something passing in front of something else and and causing the light

of the farther thing to bend and appear more bright. Um. The concept of using this two look at other galaxies is really pretty young, definitely less than ten years old. But um, this group out of Switzerland thinks according to their simulations of what this lensing would look like run against some previous telescope data from Andromeda that they may have actually observed an exit planet way back in two

thousand four. Um. They suggested at the time that it was a binary star, but yeah, yeah, based on on the simulation, it might have been a planet some six or seven times the massive Jupiter. That is incredible, And just think that's like, that's just ten years after the

first discovery of an exoplanet. Period. Yeah, that's in our galaxy. Now, of course that's not confirmed, right, Yeah, And unfortunately there's really no way to check it because of all of these complex movements of planets and solar systems and galaxies. It means that that these lensing events do not repeat. Right. We can't just train a telescope on that segment of

and wait for it to happen again. Yeah, So clearly what we have to do send someone out the check and come back, uh yeah to two million light years away or saying that's that's no big Yeah. Well, uh, you know. One of the other things we mentioned was this this search for actual extraterrestrial life. But how would you look for life on exo planets. I mean, as we were saying earlier, you're not going to resolve them up to the point where you can look at the

surface and see little people walking around. You look for activity on a Friday night, that's when life is always at its most active. No, actually, we're talking about looking for bio signatures, which are evidence of things that life as we know it generates on a planet. And when I again when I say life as we know it,

we're talking about the sample size of one planet. But we know at least this is one way it could work, Yes, and we know that there are certain things that are likely to have been made by something that was alive versus something that was not a life like there's some gases that we could detect, but we wouldn't necessarily know if it came from an organic life form or a

geological event, right, So, so those would be problematic. Even if we detected it, we could never say, for not even with any degree of certainty, that it came from life forms, because it could have come from some other source. Sure, but one example would be oxygen, because it's not natural for Earth to have oxygen. If y'all didn't know this,

Earth is not naturally an oxygen planet. The oxygen in our atmosphere is largely a byproduct of life on Earth exactly, So oxygen would be one of those biosignatures we would look for. There are other ones as well, but these are the sort of things that we would try and detect. Now, then the question becomes, hey, how do you find out that that planet that's really far away has oxygen on it? I mean, that doesn't really answer our question. Can lean

out and try to breathe it? Nope. So the way we detect biosignatures is through spectral analysis, again using spectrometers, looking at the color of light that's coming off of being you know, reflected off of that planet. So, uh, when we do that, when we look at the light that we can see coming from these planets being reflected off of them, obviously they're not emitting the light themselves.

Then you start to work backwards and say, all right, well, what ingredients had to be there for these particular wavelengths of light to make it to us? Right? Because different types of atoms will reflect light at different wavelengths and they will absorb other wavelengths, right, So you would expect to see an absence of certain ones with the presence of certain gases. And because that's predictable, you know, a particular gas is always going to absorb the same wavelengths

of light. Then we can start to work backwards that way. So we've really looked for the dominant biosignatures that we found on Earth, because that's again what we have we know to work with. There may very well be other types of life out there that are very different from what we see on Earth, but because we have an honored them, we can't know what to look for in that case. So it becomes kind of a cyclical problem. So we're looking specifically for stuff that is similar to

what we see here on Earth. Okay, So I want to talk about one more thing and follow up on that question we had earlier about colonizing exo planets, because this comes up a lot when people talk about exoplanets. We got to find the habitable exo planet, you know, where's the one we could go live out our our our peaceful retirement in the galaxy. I don't know how realistic that is, and I don't want to be a naysayer because who knows what kind of spacecraft and and

propulsion systems will come up with in the future. But based on the kinds of spacecraft we have today, I'm not sure that that's a realistic thing to talk about. Okay, so what are your objections here, Joe? I mean, what's what's the issue? Are you just think we don't have a style and enough ride? Yeah, what does a fast moving human spacecraft look like? Well, we could look at Voyager one. It is like a one ton object that's fleeing our Solar system very very fast. It's one of

the fastest things. I think it is currently the the fastest spacecraft. Um, so we may have had something that that I think was a little bit faster spiraling into the Sun, but right right now it's going very fast and we don't necessarily want to do the spiral into the Sun. Well, it got a boost, and this wasn't just drive systems. It got a very lucky boost by doing swing buys of Jupiter and Saturn, which sped it up significantly. It took advantage of their gravity to get

itself thrown out into space. There their gravity in their own orbits. Yeah, kind of slingshot up right out. Yeah, the old star trek methodology and going back in time. Right, so it's going more than thirty five thousand miles per hour, which is really fast. I've even seen some figures putting

it closer to forty miles per hour today. I'm not sure I've seen different figures, but let's just round up for simplicity and say you had a crew full of colonists who are in a spacecraft heading out from Earth at fifty thousand miles per hour. I did a little math with the help of Google and Wolf from Alpha, to see how long it would take to get to an exo planet. So I looked at Glies six sixty seven c C, which is one of the ones they've held up, is sort of one of the one of

the really cool looking, possibly habitable planets. It's about twenty two light years away, so it's one of the closer ones. One light year is about five point eight seven eight times ten to the twelve miles. That's that's very very far. And that's that's just one light year. You said this one was twenty two lights. Twenty two light years is one point twenty nine times ten to the fourteen miles,

or about a hundred and twenty nine trillion miles. Okay, so then you take a hundred twenty nine trillion miles divided by are you using the generous speed or the I'm using the super generous fifty thousand miles per hour, which is about four hundred and thirty eight million miles per year. A fifty miles per hour, it would take two hundred nine thousand, three hundred and twenty five years to reach this exo planet I just mentioned. That's longer

than Homo sapiens has been a species. So so there's no telling what what the inhabitants of said spaceship would be by the time they reached this exo planet. My thought was, at that point, you're not you're not actually colonizing the planet. You're colonizing the spacecraft itself, right, and you're probably the face of bow by the time you get there. So yeah, humans would essentially evolve to favor the conditions of the spacecraft before they reached the new planet.

By the time they got there, they might not want the planet. They might just need to live on the spacecraft. They might be afraid of the planet. So the moral of the story to me is that unless we invent much much faster spacecraft that can travel faster than light, or at least some really significant fraction of the speed of light, exo planet colonization and is just off the table.

Like if you were able to get close enough so that you're talking about a generation or maybe two generations of people to get to the closest exoplanet, I could see that being a possible. Yeah, but if you're talking longer than humans have been human, then that is an issue totally. Yeah, it's not a really good Plan B.

That's maybe a Plan X or Plan data Alpha. Well, what this comes down to is basically, if you're thinking, oh no, we're about to use up Earth, you either need to figure out how to tear aform Mars, or you need to invent some spacecraft that can travel near or faster than the speed of light, or you got to figure out how to stop using up Earth exactly right. No, I'm taking it as a given. And you're like, we're not going to stop, can't stop, cann't stop, won't stop

to say, black Fridays around the corner. Let the good times roll right right right? All right, So so maybe that's not our super best option, right No, I actually I agree entirely with what you said. I mean, it's it's a no brain or the smartest thing to do is to make use of the resources we have in

a smarter way. But but but that's easier said than done, obviously, but not Nonetheless, it would be really cool for us to find some potentially habitable planets and uh, you know, like send him a Facebook message like saying like, hey, guys, what's up. Yeah, that was actually one of the things

I was thinking of. Two is that it you know, discovering these exoplanets and finding candidates that could potentially support life might mean that we don't ever you know, inhabit them ourselves, because they're so far away that to get there would have this prohibitively long journey. But maybe if we do discover one that has intelligent life on it,

that we could one day communicate was said intelligent life. Um. And keeping in mind this communication would still take an incredly long time because even traveling traveling at the speed of light, like your example that you had, Joe, that's twenty two years between messages. I send a message out I have that, I'm gonna wait twenty two years before it even gets to the person I texted, and then I have to wait for them to you know, the message and the winky smiley face twenty two more years

for me to get the winkie smiley face. By then, the movie I was trying to see has already left the theater, so it's just not the But but this is one of those ways where we could potentially actually have a communication with with another intelligent species. But that would one depend on they're actually being one out there too. We'd have to find it, and then three we'd have to be able to send some sort of communication that they could identify as communication, and four we'd have to

agree that that's a smart thing to do. Well, if they're that far away, it's not really likely that they're going to catch up to us anytime soon, unless at least twenty two years to work at the at the very least, and more likely three hundred thousand years to work with. So I think if you've got three hundred thousand years to work with, you you could really say, like, I'm pretty sure by the time they get to wherever

we are, we will be able to handle it. We've been training for three hundred thousand years for this, so at any rate. It was an interesting discussion and it was really interesting to learn how how scientists are detecting these exo plants I've always heard about it kind of in passing whenever a new discovery comes around, but I never really looked into it seriously on a deeper level.

And it's truly as an amazing field and I can't wait to learn more about it just because I mean, again, bottom line, we're learning more about how our universe works, which is always cool. So any final thoughts, guys on exo Planets, do you want to talk about Planet Pooplon No Populonula poople on because it's it's planet. You're messing my head up now, Jonathan, No, shout out to all the puppies on Planet Populan. Your planet is the best one. I'm sure. If if anyone in our galaxy gets preserved,

I hope it's that one. All right, that's fair. I'm sure that all the cats on the internet are cursing your name, but we will we will ignore that and soldier on. So, guys, if you out there have any suggestions for future episodes, be forward thinking. There's something you've always wanted to know about. Maybe there's even a question you have about this exo planet episode we've just done. You should send it into us. Let us know we love your messages keep them coming. You can contact us

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