How Earth-Like Planets Work

exo planet? Yes? You have. Well that's all I got. I'm down. I'm done with Kepler. Kepler is pretty awesome, isn't it. Kepler is way awesome. Let's talk about Kepler. What is it? Well, Kepler is a guess what you call it? A program? Sure, the Kepler Project program. It's a mission. Yes, it's all the mission. And since two thousand nine they have Their task has been to survey the sky in fact, um, well a small patch of sky right now. And it's an outer space telescope. Yeah. Sure,

it's spine on people in the city park. No, no no, they shot it out in a space. It's dressed in like a silver um jumpsuit, so you can tell it's a space telescope and not just like a regular one. And uh yeah, it has a little twelve degree um field of vision, and what it's doing is just looking out into the cosmos in the Milky Way. Still. Yeah, specifically near the constellations Sickness and Lira. For now. For now, you gotta start somewhere, right, you only have twelve degrees.

You know, it's not the big ear. It's like a journey. You have a thousand miles starts through the singles that. Uh. Basically, what they're trying to do is see I think the ultimate goal it's just to see what's out there. But what they really secretly get giddy about and titter about um late at night is finding exoplanets that are like our own Earth. I know. I think the whole thing was a straight up planet hunting mission. Well yeah, but like I said, they're not just like we want to

find another Earth. They they're like, we want to see what's out there because we don't know what's out there. Yes, and they get really excited when it's not a big giant ball of gas. So the Kepler mission actually the first Kepler mission ended this past May because the Kepler telescope I think ran out of battery power or something like that to turn itself. But they started there. They're ramping up the K two mission, which is actually this

is so amazing to me. I love this stuff. It's they're going to use photons light from the Sun to move it. Pretty amazing. And the photons are going to move this thing called solar power to direct it and look in different directions. It is very much so amazing. Um. So the whole point is is defined planets. But really, like you say, what they're looking for our planets that fall within what's called the Goldilocks zone or the habitable zone.

And there's a couple a couple of different types of zones. Yeah, if we're talking the Goldilocks zone, what we mean is a planet that, um where there is water that doesn't evaporate immediately or freeze. Well, yeah, that's one way to put it. You know, flowing water would be great, so CEO two that'd be awesome. So the whole Earth earthlike planets, right, earthlike is what it what it comes down to, able

to sustain life, right, and the the whole thing. I've read this really interesting article, Chuck, and it was I think it was an aon magazine like it is one of the greatest online magazines ever created, so interesting, everything is so well written. It's just great. A on magazine, aon magazine anyway. Um, the the person writing this article said,

what if our conception of life is really limited? And when we think of life, we think of like um genetic genetic molecules capable of self replicating, right, like us, like life, like anything that that can make new copies of itself, cellular reproduction. Right. So, um, what if there's life has evolved in many, many other ways, not just out an outter of space, but here on this planet, Like we could be surrounded by life and not even be aware of it because we're not thinking of it

that way. We're strictly looking for evidence of um DNA based life. If life evolved in other ways and it's we're surrounded by it, that's pretty neat. That's one of those late night college conversations, if you know what I mean. But with Kepler too, it's looking for planets that could sustain a certain brand of life, which is the life that we know and the whole thing is predicated on the idea that you need water and liquid form to be the foundation, the the sustaining foundation of life. And

so that's what that's what this habitable zone is. It's a planet that is far enough away from the Sun that it can um. It's it's surface water is not going to boil away and turn it into um and just just go into the atmosphere far away from its star. Right, not necessarily the Sun. Right, it's star is what I mean. It's version of our Sun, yes, yes, oh, and but it's not so far away that it's not getting enough heat so that it just frees. So it's within this

what's called the circumstellar habitable habitable zone. It's or it's in this little distance like we are in our sun. Our stars habitable zone are its circumstellar habitable zone, right, And so it's looking for planets that um are surrounding stars in that little band that's not so close that it's too hot and not so far away that it's too cold. It's just right. I love it. That's called

the Goldilocks zone. Yeah, that's the name for it. Um. So there are they have the Kepler mission has returned UM a lot of startling information like thousands, perhaps tens of thousands or hundreds of thousands of planets maybe out there. Um, in fact, probably are out there. I think it's forty billion in the the Milky Way alone, is what estimates are unbelievable in the Milky Way alone. Forty billion Earth sized planets, not just all plants. Forty potentially Earth sized

planets in the Milky Way alone. Yeah. So, like I was saying, UM, giant balls of gas are fun gas giants like Saturn and Jupiter, they're needo torpedo. But UM, as far as science really getting um getting their rocks off, these Earth size planets are the ones that that that's where the money is, you know, right, And when I say money, I don't mean cash money, although if we

colonize them, I guess it could be cash money. But the smaller planets, what they call terrestrial planets earthlike planets, UM are terrestrial planets would be a great band name, by the way, because they are They have heavy metal cores and rocky mantle, and they have smaller orbits, shorter years, they're close to the host star. All these things that are Earth like, which could mean potentially you know something there,

so okay, so something living. You've got the circumstellar habitable zone, which is not too close to the Sun or not too close to the star, not too far away from the star. But there's also um a larger habitable zone that that kind of if you have that one, great, But there's some other qualifications that a planet has to hit to be considered habitable, and these are galactic habitable zones, right, So part of that is that it has to have a heavy metal core, like you say, it's got to

be terrestrial. It also has to um it can't be tidally locked. Right. There's we found actually some planets out there that fit the bill, except they are tidally locked with their star, which means only one side and the same side is always facing the sun, which means that that is a very very hot body of water right

there that's facing the sun. And then on the back side, the dark side, it's just completely frozen and since it's not turning, the atmosphere is not being um kept around, the planet is able to like migrate to like say the dark side of the planet and just freeze there. That's a great example of how you can have all these other things. That planet might be in the habitable zone for its star, but it falls out of the category of a truly habitable planet because it's missing some

other factors, for example not being tidally locked. So that would be the case with Gliza fight one G. So yes, okay, So that is was discovered in two thousand ten, and there's been a lot of back and forth between a lot of different countries and scientists saying is it really there? Is it not there? I think where it lands now is? They are pretty sure it's there. Um. But with Glees eight one g um, it faces uh the star at all times, one side of it does, so it's tightly locked,

tightly locked. Um. Although it does orbit once every thirty seven days, it keeps that face. So basically what they think, because if there could be life there, you have what they would call an eyeball Earth with a one part of this planet having being liquid water right and the rest of frozen, so like an eyeball in the middle kind of neat. I think what keeps Glees of eight one g in the news is the fact that it's

only twenty point five light years away. Um. And we'll talk about some more of these, but a lot of them are like over a thousand light years away. So let's take a break real quick and we'll get back to exoplanets right after this. So check you you touched on something I think is very important before we go any further there. People say, well, yeah it exists, or no, it doesn't exist. And there's a lot of back and

forth in the scientific community. And the reason is, is the as as high powered and awesome as the Kepler telescope is it really is. It doesn't look at a star and say, oh, look at that planet. That's a fine looking planet right there. It looks like, oh yeah, I can see water on there and wall like a giant pterodactyl like a monkey head. Yes it is. No,

it can't see these kind of things, right. So there's different techniques that are used for hunting planets exoplanets, um, that use deduction in a lot of ways in concert with these telescopes right to surmise the existence of planets. So um, there's three main techniques that even these telescopes us Like the Kepler telescope is it uses a photometer which senses light, right, and it'll look at a star, are and it'll just keep looking at the star, looking

at the star. It's got a really good Uh, something weird just happened at the star got dim and then it went back to normal light. And what just happened was probably a planet orbited in between the telescope and the star, which dim the light of the star. That's right. They called that a transit and that technique is called the transit method. And so they, like you said, they use that photometer and um, if they see that dim

that's a lead in the right direction. Yeah, and now it doesn't prove anything, no, so that that that planet becomes a candidate planet. So they go back and they look at it. And if they say, use a different technique, or if they um, if they come up with the same data using that same technique again and again, then most likely that planet does exist and it becomes a right, it becomes a confirmed planet. So it goes from a

candidate planet to a confirmed planet. Um. And there's a lot of criticism in this side actific community because when a candidate planet is found, it is far from being proven as existing. But um, it's very frequently rushed out to the media, which treats it like a new planet's been discovered and we know all about it, when we really don't even know for a fact it exists, And very infrequently the science behind having to deduce its existence is explained in in the in the articles that are

written about them. So it just gets rushed to press a little too premisuarly to keep that public interest up, you know. Yeah, but it wouldn't hurt to also educate the public at the same time. So a lot of people say, oh, well that we just discovered a new planet where it's still a candidate planet and it doesn't we don't necessarily know it exists. It's a good point, um.

So that the transit method is is the one where the light pulses, the star pulses, well, it dims because the planet comes in between the telescope and the yeah star. Then you have the wobble method, which is pretty neat in itself. Um. It looks for changes in relative velocity caused by the gravitational pull of another nearby planet. So basically what happens is they use the spectrum of light for this one and they analyze that spectrum around this uh what they think could be a planet. It planet

it planet it can planet it so, thank you. So what happens is if it is being pulled by another planet, when it surges towards Earth and then away, it causes variations in that light spectrum. So when it comes towards Earth, um, it shortens a wavelength and you see a blue spectrum more um. When it goes away from Earth, it lengthens and you see red more So it's almost like a color pulse. Uh. And that is the Wobble method. So that's number two. And that's the Doppler effect. Uh is it? Yeah,

but with light instead of sound. But the Compler effect is only sound. No, it's any kind of wavelength. Oh I thought the Doppler effect was strictly sound. No, it's it's it's any I'm telling you. It's the thing that links bats to earthlike planets, to Doppler to a passing ambulance. Yes, man, I'm so psyched about the Doppler effect. Uh. And you want to go ahead and hit us up with that

last one micro lensing that's pretty neat too, yes. So, um, when you have a star and another star passes, if you're looking at a star with say if um, like the the Kepler telescope, which the Kepler telescope strictly uses the transit method from what I understands, So you have another telescope that that is more open minded. Yeah. UM, And you're looking at a star and another star comes in between you and the star. You're looking at that star that's in the foreground, that's in between you and

the original star. UM actually takes the light and acts as a kind of a magnifying lens and intensifies the light of the star behind it thanks to its gravity. This is called micro lensing. Right. If a planet falls into that that's an orbit around that other star falls in line with this, it takes that um that micro lensing effect and amplifies it even further. And then you can calculate, based on the amplification of the micro lensing effect, the mass of all of the stars and this new

mystery planet that just came into into line with this orbit. UM, And they use that mind blowingly enough to deduce the presence of planets around stars too. So you've got these three methods and all of them though again it's really important to remember this, all of these used deduction, Like

none of these planets have been visually observed. They are all deduced to exist based on um, the mathematical evidence that there's something going on here, like that this light is dimming, this color is changing, or the light is being amplified by something, and it all has to do with mass and gravity. It's pretty amazing. Yeah, alright, so we'll take a little break here and come back and talk about some of these exo planets and if there

are people living there, there aren't so chuck. Remember we mentioned the transit method. You can also use these things to deduce even more stuff about these planets once you confirm they exist. Personality, right, it's signed like kind of things. Um. There's something called transit spectroscopy which uses the apparently the atmosp fear of a planet leaves a certain kind of mark on the light that it messes with in the

star that you're looking at. So not only are you deducing that the planets there, you're deducing by the effect that that planet has on the light the type of atmosphere it has as well. So pretty amazing, right, So once they figure out that yes, the planet is likely there, they go back and look at it and the planet goes from a candidate to a confirmed planet, and the Kepler Um came up with one thousand and thirty confirmed exoplanets,

twelve of which are in a Goldilocks zone. Right. Um, they really start going to town studying this planet and figuring out what its atmosphere is like, where it is in relation to the star, what the temperature is, and they can tell some pretty amazing stuff about an exo planet just from all of these deductions. Yeah, Like, uh, I guess let's just talk about a couple of these UM the the Gliza. Uh I guess it's a group

because there are several glazes. There's a gliza. So each one of these UM exoplanets is named after the star that it orbits. Yeah. So so the Glaza Gleaz is a star. Yeah, and it has several potential habitable planets

around it. We already talked a little bit about five eight one G, but there's also a five eight one C. It is twelve thousand miles in diameter UM, which is not too much bigger than Earth um, and makes one complete revolution in thirteen Earth days, which means it's too hot, but it balances that out because it has a surface temperature one uh that of our Sun, which means potentially,

and again this is all speculation. Potentially the temperature range on the surface of five eight one C could be thirty two degrees to two degrees fahrenheit, such as in the wheelhouse. It isn the wheelhouse. I think further study has kind of discarded the idea that um gleeza vibe eight one c is habitable. Yeah, it's pretty quick right

as far as breaking news goes. But you raise a really good point that if this thing has a revolution a year that's thirteen days long, the there's no part of the planet that's going to get cool enough to even things out. It's gonna just stay too hot. And conversely, if the thing has a year that lasts too long, it's gonna it's not gonna get hot enough. It's gonna stay cool. So that's another galactic habitable zone factor. Well, I love him, man, keep them coming. I know. I

basically went and looked today. I was like, what are

the most likely habitable exoplanets? And an article from a year ago has a top five that's different from an article now, Like that's how quickly things change, right, Well, I mean these things were all just basically theoretical, like we assumed that, you know, a star would have planets orbiting it, but it wasn't until the Coupler mission within the last like ten years or so, I think it was from the Arecibo telescope was the first confirmed exo

planet to be detected. And that was but once Kepler started going, it's they started to come like hard and fast. And once they started and people started rushing to press, then the science is having to retract them now and things are going from yeah, well, well there's a new exit planet that we could just travel to now if we wanted to to. This thing actually doesn't exist or

it's not really habitable. I looked. The most recent one I found was from like three months ago and May of this year, and they say, I believe this was from space dot Com said that Kepler forty eight B is the most earthlike planet yet that we've discovered. Um it orbits a distant star in the constellation of Lira, which is where Kepler is looking. Which eight B. It

gets really confusing. They need to start naming these things, they do, you know, So four thirty eight B is a little bit bigger than Earth, uh more heat than Earth than what we received from the Sun though. UH. It's small though, which means it is UM just because it's twelve percent larger means it's seventy has a seventy chance of being rocky like Earth. UH. It is four d and seventy light years away, which is not too bad considering some of these are thousands and thousands of

light years away. UH completes an orbit around its star every thirty five days, which is about ten times as fast as Earth. UM. And basically the Harvard Smithsonian Center of astro UH for Astrophysics said that UM, they announced this one along with seven other planets UM in the same habit of ball zone. So decent chance. But UM, like I said this this, By the time this comes out,

this may be old news and debunked. Who knows. UM. There's another one that I think they discovered even more recently, which is Kepler fifty two B and it's light years away UM, and it is an earthlike planet. I think it's UM like uh si larger in diameter than the Earth UM, but it's still Earth like. It is a super Earth, yes, UM. No, that automatically qualifies it as a super Earth. So it's it's Earth size, but it's not so big that it's like a gas giant. It's

terrestrial likely um. And it's in the Goldilocks zone for its star um, and they're pretty excited about it. Actually. I think the it has a mass that's five or six times Earth's and so you would be you you would feel about double your weight or you would weigh double. Well you do here. But they think that if we did sink colonists there, their bodies would adapt to be like working out all the time. Um, but you would become super strong, and if you came back to Earth

you could just beat everybody up. Interesting because you'd be twice as strong. Pretty cool, huh, it'd be great. That's the point of space travel is to find ways to just walk around and come back and beat everybody up on Earth. It's a bully program. That is a good question, though, what's the point of all this? If these things are light years away? What's what's the point? Um geez, just to keep looking beyond? I mean, isn't that exploration the

whole point? I guess, because it's not like we could colonize any of these places, well not now. But I think that some people have an eye toward that that the if we ever do figure out interstellar travel, um, it would be really good to know where we could go and take off our helmets and breathe. Yeah, I think of it more in the opposite way, like you can't stop doing stuff like this. No, I agree with because then you've just I don't know, then you're just

you've given up. You're an isolationist. Yeah, you're adults living on Earth and o'tre I'm just gonna die anyway. Well, the other thing that they're looking for that that exoplanets searches bring into the fold is steady the search for estratra extra extraterrestrial intelligence or just the search for life um elsewhere. And again, if you're looking at planets that can sustain humans, they could conceivably sustain other types of life as well. So we're hedging our bets for the future.

We're also looking to see if we're alone out there or not. Imagine there are people out there that thinks there's a big waste of time and money though probably you know, whatevs. The adults, the isolationists, you got anything else right now? Oh? This is uh, this is good. Stuff is a little heady and it's such a rapidly changing thing. Yeah, we could revisit this easily. Yeah, I mean this will be outdated in six months. But tops, Hey, we we like to do these topical things every now

and then. Uh, if you want to know more about earth like planets, you can type that into the search part how stuff forks dot com. And since I said search parts, time for listener mail. I'm gonna call this, uh road rage and no not road rage. Citizens arrest. Okay, there's kind of a difference, big difference. Guys. Have a citizens rest story. Um from two thousand one. I was a naive nineteen year old behind the wheel of the

first car ever bought myself when I was rear ended. Um. It was two thousand one, so we didn't have cell phones and there was no phone booth nearby, so we could not call the highway patrol or police. The other driver had insurance, but did not have a valid driver's license, only an expired one. Later found out he obtained a license during a window time when the Governator of California announced him to be issued to undocumented persons who had

emigrated without completing all their legal steps yet. So basically this guy got in a window had it license at one point it was expired. I got my crunch car home that afternoon and, at the suggestion of my parents, called the local cops to file a police report since we couldn't do one at the scene in the accident. The officer that came out to my home was the most militant, sour woman in law enforcement that I have

ever had the pleasure or displeasure I'm encountering. She impatiently asked the questions and took notes, all while sneering at me. When I got to the part about the other driver having expired license, she literally yelled at me for not placing him under citizens arrest. Mind you, this was a car full of men. I was a nineteen year old girl who weighed a hundred pounds and was four ft ten, and she chastised me for not placing an entire car full of grown men under citizens arrest for driving on

an expired license. Uh. She went on about how many undocumented persons have criminal records and can be very dangerous, and this would have been a good opportunity to get them deported. Well, this is an explosive listener mail. Yeah, or a car full of potentially dangerous men. Maybe you should not try and place under citizens rests would be my idea. At this point, my father had enough of her shenanigans and asked her to leave. That was the end of that, but we still chuckled this day over

the absurdity of her suggestion. Uh. And she goes on to say that the guy in the car and the dudes were very nice, and the exchange insurance and it wasn't like a bad scene or anything. So, um, it just sounds like this officer was not a very nice persons. Like, yeah, and every cop that we heard from after citizen arrest said don't do it, and this lady saying, now try it.

A little four ft tin lady shot on a car full of men, and um, all of sudden, you want to point out that I forgot that one of the most legendary Remember I was trying to think of famous citizens arrests. The most legendary of all time is, uh, the night Stalker. Oh yeah, he got arrested by a citizen by citizens Like he was checked the knight Stalker

did no not him? Richard Richard Ramirez. He was recognized out on this because they eventually found out who he was and blasted his face out everywhere in this group of Hispanic women saw him and started screaming in uh in Spanish like night stalker, night stalker. And he was gang piled by like fifteen people and cops had to pull people off. He was almost beaten to death. So I guess you would call that a citizen's arrest. I would call that, yes, yeah, like a good one, yeah,

an effective one. Yeah, well they got a serial killer. You always gotta feel good about that citizens arrest. Yeah. I fell down the rabbit hole of reading all about that guy recently. Yeah. Yeah, man, what a crazy time to be living in l A. I bet people were because there was no rhyme or reason and it was like one night, then two nights later, than three nights later, than two nights later, and just crazy, awful, awful things. That was like The Zodiac, one of my favorite movies

of all times. Zodiac. It's a great movie. That was a great one. But then you read ramirez is background and it's like abusive father, Um, this crazy uncle that was in Vietnam that showed him pictures of like decapitated bodies, and you know, he was dropped on his head like three times, like he had a whole list of things that's like how to become a serial killer. And uh so it's two times you're fine, that third time you

get dropped on your head, that's big. And let's not say every head trauma leads to that, but they think it could have something to do in cases like that. It was just it was very sad and fascinating. Yep, do you have a particular article you recommend on the dude? Uh? No, Okay, well look, come up. Yeah, uh if you want to let us know about your personal story of something that has to do with what we've talked about in the past, how's that for call action? You can tweet to us

at s y s K podcast. You can join us on Facebook dot com, slash stuff you Should Know. You can send us an email to Stuff Podcast at how stuff Works dot com and has always joined us at our home on the web, Stuff you Should Know dot com. For more on this and thousands of other topics. Is it how stuff Works dot com.