Other Earths. Other Life. | Sara Seager

[Music] good evening I'm Alexander I'm the executive director here at the long now foundation and as many of you know we start these talks with a long short a short film about long term thinking and tonight's one is one that I've I chose a long time ago and when waiting for the perfect the perfect talk to do it in and while Sarah is going to be speaking tonight about exoplanets planets in systems very very far away from ours this film The Wanderers is a amazing piece that shows how much more discovery and exploration we can do of some of the worlds in the nearer space thank you [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Applause] [Music] [Music] I feel like I should walk on here with something other than boring old 1g hi I'm a Stuart brand from the long now foundation I've learned about planetary atmospheres in the 70s because Koval even quarterly which I added then was the first u.s. publication to publish to the Gaia hypothesis by Lynn Margulis and James Lovelock and Jim tells the origin story of the Gaia hypothesis that he was working you've been hired by Viking as a atmospheric chemist who had developed the electron capture device that was detecting those own apart spending and DDT of parts per million and so on and they asked him to look at basically spectral information coming from the atmosphere of Mars and tell them if there's anything interesting about it and he said well the interesting thing about it is it's in perfect chemical stability which means there's no life on Mars sorry you're saying at which point NASA said that's very interesting I'll be quiet about that now and he was but it made him realize that the extremely unstable chemistry of Earth was a signal not only of life but of some processes he began looking at and how has become birth system Sciences looking at the presence or absence of life on planets there's an atmospheric issue so it'd be nice to get somebody to talk about it who's written a book called exoplanet atmospheres sir seeker [Music] thanks Stuart thanks everyone for coming out well the funny thing about atmospheres is that even when we think we understand them in a global sense there's a lot of small things that don't always make sense this year in Boston in winter we got over 100 inches of snow which for us was great it was a record but the funny thing is is coming out here it's way colder than it is in Boston so here we are with a view of the night sky and I wanted to just start out by reminding all of us that every star in the sky is the Sun and if our Sun has planets surely all these other stars should have planets also and they do and in the last 20 years or so we have found thousands of lenez and we believe now that every star in our sky has at least one planet and planetary systems are just so common whenever I look up at the stars I always wonder is there another planet around that star and are there any intelligent beings on that other planet far away looking back at us I really hope they're out there and I hope that someday we're gonna find them and so what we're looking for when we talk about looking for another planet that might be like Earth is looking for Earth a pale blue dot far away and this is actually a real photograph of Earth by the Voyager 1 spacecraft this was orchestrated by Carl Sagan and it was taken from four billion miles away and believe it or not most of my work about atmospheres it is about how to take a little dot like this whether it's a star or a planet and in the future another earth and try to infer everything possible about that planet whether there is water on it or signs of life by way of gases in the atmosphere that don't belong so what I'm going to talk about today is what is an exoplanet when and how will we find another earth can we go there if we can't go there why look and by the way these are the questions that I get asked most often by people of all walks of life from children to elderly people to you know people I meet on the plane to actually everyone and you know what the most popular question is it is can we go there and even when I explained it how we can't really do that right now I still get asked it over and over again even during Q&A so I'm sure some of you are are wondering about that now to get started I wanted to leave you with something to take away when you get home tonight or in the coming days I want you to google for eyes on exoplanets and download this software I didn't write this I wasn't part of it I just loved it so much I have a little clip of it to show you and it starts out here with an artist's illustration of what we think our Milky Way galaxy looks like from far away a galaxy is a collection of bound stars and our Sun would be about here with respect to the billions of stars in our galaxy and this is just a little clip showing you our Milky Way and these zooming into where our son is you can see the stars here and all the highlighted objects are stars with known planets the different stars are different colors red is a small star yellow would be like our Sun white would be something brighter than our Sun and now this clip just keeps zooming in to our planet Earth it actually also shows you some spacecraft that are orbiting our Sun epoxies here you can see Spitzer and Kepler now you can use the software and here we're gonna click on the west coast of north america looking up at the spring night sky and overlaying the constellations here actually you could actually do this now if you download this software for tonight or anywhere on earth where it's dark at that present time and look up at this guy and it'll show you a real map of the stars now here it's overlaying the constellations of course those are not conveniently drawn for you out in the sky and also many of the stars you couldn't see them just with your naked eye you'd probably need binoculars or a telescope you can see this is gonna actually now rotate to zoom into a very special part of the sky look at that does anyone know which part of the sky this is yeah this is the Kepler space telescopes field of view and there's such a concentration here actually no the whole sky really that's when I said that we think every star in the sky should have a planet because we actually know that from a specific technique called micro lensing but on the whole there are a lot of planets out there now the thing that's really nice about this software is you can actually use it to search for a planet by name in case you happen to have a favorite planet whose name you know one of the favorites from astronomers or the public or anyone really is kepler-186 six and if you zoom on it it'll actually take you to this in this real map of the stars where kepler-186 is and you can take a kind of a look at it and its orbit now this particular system has several planets but the reason we're excited about it is the so called kepler 186f in the planets habitable zone now here you see the habitable zone is shaded we don't know exactly where it is but what the habitable zone is is it's a region around a star where if a planet is in that orbit it will be heated by the star not too hot and not too cold but just right for life and now in this movie clip it'll keep zooming in on kepler 186f but here's where the fine print you can barely read it it says hypothetical visualization of planet we don't know this this is the part we don't know we know about the real map of the stars but we don't really see planets in that level of detail quite yet actually actually we might never do that in our lifetimes but that's the software it's called eyes on exoplanets and you can spend a lot of time clicking on the stars and fooling around with it and I really hope you all are able to do that but not now during my talk so actually what I work on is planet atmospheres and what planets look like from far away and I write computer code and all my students also do but before I get to some more details I wanted to just take you on a tour of some of our favorite planets so here's a poster actually kepler 186f yeah it's a travel poster it says well kepler-186f where the grass is always redder on the other side because kepler-186 is a small star it's a red dwarf star and some people actually have worked on this thinking that perhaps plants and vegetation is a different color taking advantage of different wavelengths of light that the red star would be brighter at than our Sun next travel hoster is for experience the gravity of HD 403 o7g a super-earth and here they're showing someone parachuting but here in this case the planet is has a surface gravity of about one and a half times the size of Earth Kepler relax on Kepler 16b the land of two sons where your shadow always has company and in this particular poster is showing an astronaut on a planet that's orbiting two suns we call these circumbinary planets and now we know of about a dozen of them it's a planet that orbits two suns and actually as long as those two suns are close together and the planet is several times further away than that distance between the two suns it should be gravitationally bound and what I like about this is well science fiction got some things right one of my favorite planets is Kepler 10b this is what we call a hot super earth it is so close to its Sun that it's it's based on Kepler's law The Closer planet is to a star the shorter its orbit the faster it orbits and this planet orbits orbits the Sun entirely in less than one Earth Day is zipping around that Sun the planet is so close to the Sun that it is heated by the Sun the surface would be so hot we think hot enough to melt rock and in this artist's conception here they're showing you just that they're cracks and just it would be like going outside and instead of seeing a puddle of water it would be a puddle of of rock only we could never go there because we would melt long before we reach the surface now the last one I'll tell you about is Gliese 1214 B in this particular one you can see the nebulosity because the artists think this was too boring to just show you the planet with the star and in this case we actually don't know much about this particular planet it's we know about its mass and its size and we don't know a lot else about it actually and most of these planets we just know their mass and size and the amount of energy reaching the surface but this what planet is of interest because it falls in a very intermediate mass and size range actually it's too big to be an earth but way too small to be a Jupiter and even too small to be like a neptune and what that means is that this particular object it actually has no solar system counterpart and we don't even really know what this planet is made of Gliese 1214 B it could be a big rocky planet surrounded by a massive gas envelope or it could be something we think about we call it a Waterworld a planet that would be like one of Jupiter's icy moons 50% water mass or more a scaled up version of that and if this planet was predominately water actually we think it's pretty close to the star it's pretty hot that it would have a thick steam atmosphere and under that atmosphere wouldn't be a layer of liquid water but would be a layer of supercritical water a kind of material that's not quite a gas not quite a liquid and that would actually be over a high Persian of high pressure ice I would say like ice 9 but no ice 9 was just a joke in the novel not a joke not serious but these high-pressure ices is where water is squeezed together until it becomes solid so all sorts of different types of materials inside planets and could be out there and I just wanted you to know that there are lots and lots of planets this graph is showing you all the planets found by the Kepler space telescope to date as of July 2015 and what you're seeing here is the size relative to earth radius so Eartha would be here at one earth radius and at the bottom here it's just telling you about the planet's orbit orbital period in days so this would be a planet of one day out here at 365 you'd have earth but just look how many there are there's thousands of planets out there and those are the only ones we even know about and I want you to take a look at this graph and and you can actually think for a moment and see where are there them where's the graph that most dense where are the most points I'm trying to ask you can you see what is the most Commons planet size and on this plot you can see it's sparsely populated up here in fact so these jupiter-sized planets are not nearly as common as planets down the size of earth or a little bit bigger actually and this is one of the biggest findings actually in exoplanets and I'm guessing you don't hear about this many of you wouldn't have heard of this at all but the most common type of planet out there is something small and this is really puzzling actually because all the things that we were taught at least in planetary science is that the end product of planet formation should be a big planet like Jupiter where Jupiter is born and material creats until it gets massive enough - like a giant vacuum cleaner just suck in all the material around it until it exhausts its feeding zone and we always believe that the end product of planet formation would be a big planet as big as it could possibly be but in fact it's not true and for many of these planets in here about two to three times the size of Earth Neptune is up here at four or 3di we actually don't know how those planets formed and so we're left with this kind of really big puzzle from exoplanets now out of all the planets were looking for the ones we want to find to in the future be able to search for life on them are the so-called Goldilocks planets planets that orbit from the star they're not too hot not too cold but just right and this is a little complicated I'll come back to this a little bit later but it's the so-called habitable zone or Goldilocks zone so what is an exoplanet a planet that orbits the star other than the Sun thousands of exoplanets are known to exist and we expect that nearly every star has a planetary system all right how and when we find another earth well it turns out that our earth is very very hard to find and we actually use this analogy that looking for an earth would be like looking for a firefly next to a searchlight but that firefly in searchlight would be thousands of miles away like the distance from here to Boston usually I'm working in Reverse I'm usually in the East Coast I just say it's like looking here but think about that for a moment a firefly our earth compared to our Sun is 10 billion times fainter that's such a huge number and I want you to think about for a moment what could you in turn to think of one to ten billion what could you buy for one dollar it's like actually not a whole lot nowadays and now think for a moment could you get four ten billion I mean such a huge number our earth is so faint compared to our Sun that's our analogy here and I want to tell you a bit about this picture where a number of years ago I was consulting for National Geographic and they actually wanted to take a real picture of this anyone here who's a photographer I think you know you don't really have the dynamic range to detect the Firefly next to the searchlight they punched it I think you can see here Firefly and the first thing I was my job to tell them what I liked or what I didn't like or what was right or what was inaccurate and the first thing I said which was inaccurate was the searchlights here look how they're all together they actually rented the searchlights and took it to a field and made this picture and I just said look we don't see stars like this you never see four stars together nonetheless I think you all know what a great publication National Geographic is and the photographer's came back and they were amazed they were so excited jumping up and down they said well we couldn't take a picture of the Firefly next to the searchlight but we could take a picture of the Firefly in front of the searchlight and they actually had inadvertently discovered a whole different way to find planets we already knew how to do this but they had found it on their own it's called transits and how many of you have heard of transits okay so I'm gonna explain to you for those of you who don't know but basically if you have a planet going in front of a star instead of being a one part in ten billion contrary difference it's only well I will say only one part in ten thousand for an earth going in front of the star it signals one part in ten thousand and if we can get a big Earth going in front of a small star then that's only one part in a thousand and that's a much easier number to to handle actually for any kind of measurement and so to tell you what a transit is and why today we're always focusing on transits it's just an easier thing to see than a planet directly so here's showing you a planet can you all see the little planet going in front of the Sun it's supposed to be earth size compared to our Sun we don't see any other stars other than our Sun spatially resolved like this and there it is and look at the bottom here there's a graph of the planet going in front of the star and when the planet finishes going in front of the star that drop in brightness goes away going to show that to you one more time because this is actually the way that we find most planets today there find by the so-called transit method and just in case this plot made it look too easy you know what it's at least 10,000 hours per planet yes because we look at lots we meaning the whole community has lots of data looking at hundreds of thousands of stars searching all of them just for this very special signature of a planet going in front of a star that works on the right time scale and is the right drop in brightness and even then many other things could mimic the planet so I'm going to show you some real transit we call them transit light curves and here you can see the this is just time in hours and these are all giant planets the transit lasts for a few hours this is a few hours in here and it's also showing you the size of the planet compared to the size of the star and where the planet is crossing on the star and actually you can see they're all different sometimes people would call this like a family portrait and they're all look a little different they're different sizes compared to the star they transit a different part and so now I just have to show a few more technical slides because I was thinking some of you do know about exoplanets and some of you may have heard in the news about two weeks ago there's a planet called kepler 452b and so yeah some of you have read about that so it's just gonna shed a little light on it first that's the artist conception which you would have seen in the news and I wanted to show you what the real data looks like and here is kepler 452b this is a so if you don't understand the next two slides you don't have to understand the rest you don't have to understand them to understand the rest of the talk but I just wanted to give you something to chew on so this is days actually and this is like 200 days 400 days out to 1,400 days this is a few years of data Kepler space telescope looked at that one patch of sky for four years and all of these are points of data taken by the telescope and so remember we're looking for a star that's constant brightness and time and looking for a tiny little drop that signifies a planet now I don't know if any of you can see that drop on here first of all you note these gaps are it's when the spacecraft wasn't taking data sometimes it had a problem and went into safe mode where it didn't do anything other times when it was down linking data to earth kepler couldn't take data it actually had to rotate four times a year so the solar panels would be pointing the right way actually no what's really funny is they gave you a little signal here the triangles are you can't see it actually you can't see it in the data and indeed computers would search for it we wouldn't do this by eye although initially people looked at the data by eye and when computer finds a signal a drop in brightness it will bend the data together it will take all that data and fold it onto the same period and phase and here's what the transit light curve looks like so this is what it looks like the detection went from the space telescope taking data for four years using computer algorithms to search for these little tiny drops in brightness and putting the data all together to get this little tiny drop in brightness and this here is several hours and this little drop here looks like it's just about let's say a hundred parts per million but in my one more technical slide this planet was claimed to be the most earth-like ever planet ever found that meant it's about about the size of Earth a little bigger and it's receiving about the same amount of energy from its star so just for those of you this is my last kind of technical slide this is planet size compared to earth size and this is the amount of at the bottom it's showing you the amount of energy compared to our Sun so earth would be down here right at the bottom of the graph at one earth size and this other planet we don't know it's this is what I wanted to convey to you we do not know the planets exact size we do not know exactly how much energy from the star is hitting the planet all we know is that the planet could be any size and any amount of energy from the star hitting the planet in this box here in this oval rather and so here's where the habitable zone is for this particular planet so if the planets if we could make a better measurement and found that the planet was here it would be way too big and way too hot to be habitable so this was just a more complicated way of saying we don't know everything about the planet actually we only know the size and and approximate we know the size with some uncertainty and we know about how much energy is hitting from from the star hitting the planet top of its atmosphere also with some uncertainty so what we'd like to do is find planets around stars that we can study in more detail and what we're gonna do next is in the search for other Earth's we're looking for transiting planets and I want you to know that there are stars actually of all different sizes there are these giant stars really huge the yellow one is like our Sun it's just a cartoon diagram to show you all these different stars sizes to scale there's this red giant with such a hugely evolved star and now look at this little planet I stuck on here this is about the size of Earth this would be the size of our Sun I now look at this red dwarf star a small star very common type of star in our galaxy and look at that planet do you think that planets the same size you know it is the same size cuz I just cut and paste but it looks so much bigger here look how much bigger it looks I'm just trying to show you that actually that planet is blocking out so much more of the star the small star compared to the Sun and so actually what we're gonna do in the search for another earth is we actually will combine the most favorable planet finding technique transits for the smallest planets and the most favorable star type so that's our way to go forward actually it's to look for a big earth or an earth-sized planet transiting a small star so in this case we're not going to find like a true earth twin it's more like an earth cousin but let me actually describe it a little more by taking you on a virtual trip to this small planet translating a small star first of all that small star has a much lower luminosity output than our Sun and imagine for a moment like standing near a fire if the fire is really small you have to get closer to it for the same amount of warmth compared to a bigger fire so for these small planets orbiting small stars the habitable zone is much closer to the star and so in this case if we were to be able to visit this planet actually the Sun would be very big in the sky huge like this and this artist's who made this image also is showing you other planets in the same system and the artists also use the artist's license to make it a red sky with purple clouds now on this planet believe it or not that the planets that are close to the star because of tidal forces from the star it turns out we believe that most of these planets would show the same face to the star at all times just like the moon shows the same face to earth so that means that every time it rotates once it goes around the star once so one year is equal to one day actually but what this would mean for us if we were visiting the planet is that the star or the Sun would always be in the same place in the sky at all times so you could choose to vacation where it's always daytime and sunny or you could choose for the astronomers you would choose to go where it's always dark but actually you might want to go where the Sun is always setting because that would be permanent um now if you're on this planet for any children who might be in the audience the good thing about this is the year is so short because the planet is close to the star and because of Kepler's law a closer planet orbits more quickly depending on the mass of the star and so in this particular example I chose that planet would be orbiting the star about every 20 days so you'd have your birthday every 20 days but that wouldn't be so great for the parents okay now if we were to be able to visit the so-called small planet transiting the small star it actually may not be so great after all because these red dwarf stars tend to have a lot of flares they're very active they have a lot of activity and that means that if you're using your phone or any electronics it may get knocked out and it wouldn't be so great maybe for us if we could visit because all those UV rays coming from these M stars are very active would be very bad for our health so we'd probably have to go go to the dark side and I want you to know that over the years a lot of scientists go back and forth they've complained about these planets well if it's tightly locked one side is getting heated the other side is cold this could be a real problem for the atmosphere it wouldn't be though the atmosphere would circulate the energy or they'd say well it's so close to the star it might not be able to get water delivered to it from asteroids we're not worried about that and the reason is because it's really just a great shortcut a shortcut to earth 2.0 is finding a super earth like a big earth transiting a small star and how will we find another earth just some rice will use transits it's the most favorable planet-finding technique will search small stars with the habitable zones close to the star and will consider super Earths so actually I just want to share with you something you may not know about it's called transiting exoplanet survey telescope or tests and test is an MIT led NASA mission it's gonna launch in 2017 and it builds upon the Kepler the pioneering Kepler space telescope and tests actually what it's going to do actually is find you know it should find a few more thousand planets actually but number is we're not really necessarily interested in quantity we want quality and we want to find those small planets transiting those small stars so that we can look at their atmospheres later and we'll do that with another telescope called the James Webb Space Telescope so I just have a couple pictures about tests it's actually one of my main jobs now is to work on the test Science Center and here's actually a model of tests it's actually not that big right it's about about a big like industrial washing machine here's the pIJ or Drecker that's myself here's another physics professor here's the deputy pi roland van der speck and this here you can see the antenna this is just a spacecraft bus but inside that bus actually are four basically identical cameras think of this like a glorified telephoto lens and to show you a picture of the lens this you put your smallest person in the photograph so that the lens looks really big um actually what it is is a giant baffle and this camera here it's just a lens with a special CCD detector and this was one of the examples we had to build a prototype and test it shake it like to see if it would withstand the launch the vibrations from launch and he did thermal cycle it he didn't cool it and he didn't cool it to see if it could survive and this was actually at NASA headquarters a few years ago when we had our final presentation for which we won the competition to get selected okay so see what else I can tell you about this it's about a hundred millimeter effective pupil diameter and the bandpass would be all visible wavelengths actually it's a special camera though you wouldn't like just get this at the store it's specially designed to be a thermal and not to have any I mean you probably don't notice this if you remember your camera like from let's say the old days it could have vignetting or like weird behavior at the edges this is made to not have that actually because we want to get as much great quality data as we can so how and when will we find earth 2.0 well we really think we have a plan for it it's the whole community NASA will launch a telescope in 2017 it's an all Sky Survey for these big Earth's transiting small stars if this earth exists out there around a small star we have the capability to find it and identify it by the 2020s and in a moment I'm going to come back and tell you a bit more about atmospheres and other things about planets but I wanted to next get to this kind of follow-on question well if we do find a planet and look at its atmosphere and see that it looks interesting can we go there okay so to talk about that it's worthwhile to think about distances in our solar system and beyond and here's a real photograph of our Sun how big do you think earth would be compared to this image this actually is a sunspot and it's about the size of Earth I actually had to search to find the right photo but this one does the job the next question is if this is imagine the Sun is the size and the earth is that that size where would you think earth would be physically speaking if we were to make a model of our Earth's Sun distance to scale why don't you raise your hand if you think you're where maybe where the earth would be it's a bit of a trick question okay well it turns out that Earth actually is about a hundred Sun diameters away from the Sun so if you just think of this that was just a lucky coincidence actually but if we just imagine a hundred Suns now I think it would be outside of this room probably out on the street somewhere maybe a couple blocks away so that's how far earth would be from the Sun now for a moment we have to I want you to imagine if this is our Sun and that's to scale where would the next star be this one actually have to calculate because they didn't realize the Sun was gonna be this big on the screen so I should probably answer that one myself I would have to guess it would be about mmm let's see sometimes I forget what city I'm in you know cuz I travel so much now that's not true let me think for a second I think I'd have to put this somewhere in Russia Russia's big enough to give me an area of uncertainty he didn't far far far okay so the point is that stars are very far apart you know most of space is empty actually and Alpha Centauri our nearest star system is 4.22 light-years away so actually it's far and Voyager one would take over seventy thousand years to reach the nearest star if it was pointed in the right direction so that's a really long time but I've seen that this is just thinking how to phrase the next part where you know used to have this huge giggle factor someday let's try to go to a nearby star but you know what actually that is slowly going away actually and even just this afternoon I met with some colleagues and people are really getting ready for this you know we wanted to look for planets around Alpha Centauri if there's a planet there we believe someone will figure out how to get there and that will be longer than a hundred years that it's going to take to build the clock but I think it's gonna happen actually and I don't know how I don't know exactly how I just know that it's the drive to go there is so strong and in fact some people think engineers that are alive now on this planet that we could find a way to go let's need a tenth the speed of light that that is kind of within reach at some point and let's imagine for a moment that that's the case let's see that would take about oh if we could travel at the tenth the speed of light it would take about forty four zero years to get to the nearest star that doesn't include speeding up or slowing down but nonetheless I was wondering if there's anyone in this audience think about how old you would be forty years from now if you would actually consider making the trip should we say that we had a way to go there I mean actually you know every single time people would go another stuff to say because I always forget to say well it would be a one-way trip and would you still go and yes actually everywhere people have this desire to go so although we can't go there now you know I no longer say it'll never happen I think sometime it will happen it will be galvanized when we find a planet around Alpha Centauri so can we go there not for now okay if we can't go there why look and now I get to my part of my favorite part of the talk I call it the real search for alien life and this is what I work on this is my main reason my favorite thing when I get to work on on research and it's about the search for gases in an exoplanet atmosphere that might be attributed to life but first science fiction said we have to travel you know these yeah it's so funny because in science fiction they always said we had to travel there like the enterprise would have to travel at great distances and incredible speeds to get an orbit around an alien world so that Spock could analyze the atmosphere as habitable and if they were life-forms on the planet and the thing is that you know they never thought well why don't we just build like a ginormous telescope and look for far away and we don't know actually if they did that or not but it would have been a pretty boring show if they just did that so you know we don't have to figure out warp speed and I hate to dissuade any of the junior engineers but right now we do that actually we take we observe planets from far away and here's a real photograph of the Hubble Space Telescope which we use and we meaning the community uses and this actually was a real photo taken by the departing space shuttle Atlantis after it did a final servicing mission to Hubble and Hubble actually we use it to study planet atmospheres and I just want you to know that although we don't observe small planet atmospheres yet we do not see anything like an earth-sized planet atmosphere we have studied a giant planet atmospheres hot giant planets they're the easiest atmospheres to study they're big hot atmospheres they have water vapour and other things in it that makes it easy and so I'm just gonna spend a few minutes telling you about how what we're looking for and why and how it all works so you can have something to take away well here's a picture of a picture of a rainbow and I hope everyone here has got to see rainbow at some point but in this rainbow what you probably haven't seen them because if you look at the rainbow in a lot of detail you know you could actually see that some colors are missing some parts of these colors are actually missing and if we actually take the sun's light and spread it out not by refraction and a rain drop by a special instrument called a spectrograph we actually see this and here you see little tiny parts are missing actually and these are due to absorption either in the sun's atmosphere or the Earth's atmosphere or both and I want you to see here there's very different lines missing and see this is a really big one there's some very thin ones and they're all over the place actually and each atom and molecule has a special set of lines that it absorbs and these missing colors its absorption by gases in the atmosphere and it's been studied for many decades we're still studying it now actually and you can either measure it in the lab or other people can do very complicated computer quantum mechanical calculations because each molecule has a specific fingerprint in each atom and you can actually work out what all these these lines are actually it's there are a few things we don't know and actually it's just reading today on their way over on the plane there are these things called the diffused interstellar bands that even in between stars there's the tiny tiny bit of gas and there's some things we don't know what they are actually and they'd finally identified these bands do you do like a buckyball a giant form of carbon so anyway this is the atmosphere and I wanted you to know that the so we call this spectra are required to identify as planet as earth-like because earth and Venus are about the same size and about the same mass and they fall in that member that uncertain habitable zone I showed you the graph we don't totally know where if like kepler 452b we're not so sure of all the parameters so earth and venus would basically be identical to any planet search technique today and unless we can get a spectrum and identify the gases in the atmosphere we we need to be able to move forward by looking for gases in the planet atmosphere I just have to pause for a second and ask if anyone was keeping track of time I'm Stewart were you keeping track of the time because I didn't notice what time we started so okay so alright so the question is what gases should we be looking for in another planet and here we have on our own earth we have studied it literally in every type of detail you could imagine on our own planet Earth oxygen is our bio signature gas we think that on our planet well we know in our planet that oxygen fills our atmosphere to 20 percent by volume and you know without life without photosynthetic plants and photosynthetic bacteria there would be virtually no oxygen and so oxygen is filling our atmosphere to 20 percent by volume and that is what we call our most robust bio signature gas because it's such a highly reactive gas it shouldn't actually last in our atmosphere at all really it should be it shouldn't be there actually and we have other gases too we like like methane nitrous oxide we actually have a whole list of gases here we have things like called dimethyl sulfide methyl chloride we're kind of slowly working our way through trying literally to exhaust every possible molecule that might be produced by life it turns out that even like when you walk through the pine forest and those chemicals coming off of trees that makes it smell so nice those technically are bio signatures they're just produced in such tiny quantities that you know we can't see them from far away so there's this huge kind of branch of research that's just starting to flourish now about what types of gases should we be looking for in planets far away and we can come back to that in the qat if you have more specific questions about that so if we can't go there why look we call it remote sensing to search for gases in a planet atmosphere that might be attributed to life and this is actually a really really hard problem because although we've observed several exoplanet atmospheres already giant planets we mostly understand what we're seeing this whole thing about finding life is a real challenge and we've made it all sound so easy up till now if you've ever heard about this or just looking for gas as far away oxygen is so great but actually almost any other gas other than oxygen we have to assess whether it is present in levels so far out of equilibrium that it shouldn't be there and then we have to try to rule out every single possibility before we can even say it might be made by life but the problem we're facing is that unlike that earlier example we don't really know what the equilibrium state is when you say we want to find a gas that is so far out of equilibrium because planets are complicated gases are coming out of the surface the star has ultraviolet radiation the same thing that creates smog in our cities it's also creating chemicals and so we're really trying to work out every last possibility we're working hard on it now so for the last part of my talk I actually have to tell you about something that is really probably one of the more exciting things going on right now but I have to let you know that transits are only the first part of a long story because these transits when the planet goes in front of the star and the star light drops in that tiny amount it's only possible for very perfectly aligned planetary systems okay we think that all planets all stars are born in a random way that means that their rotation access could be in any direction it's just a random part of how the ball of gas that collapses to form a star actually ends up being and it just means that the planet's orbit could be like this or like this or anyway it won't necessarily transit and in fact for an earth the chance to transit for an Earth and earth earth earth systems from our Sun around another sun-like star is just one part in 200 and so if we want to find the nearby earths the ones someday we might go to the ones that will be bright enough for us to study their atmospheres we actually have to do a whole different technique and that comes back to that Firefly analogy where the star is so bright that the glare is bleeding all over the detector we need to find a way to block out the Starlight so we can see the planets directly and here there were conveniently three planets so we call that direct imaging where we will block out the Starlight and see the planet directly now there's a main challenge here in in blocking out starlight and that has to do with the laws of physics called diffraction and here I'm showing you a circle imagine that your telescope mirror is this actually imagine that we're blocking out the Starlight by like a giant screen in space that's a perfect circle you'd think we would just block out the Starlight perfectly but that's not what would happen actually we would see this ringing pattern called Airy rings and this analogy I want you to think about light being like a wave where if you drop a pebble in a pond you would see ripples it's a similar kind of thing so look at this if you drop a pebble in a pond you'll see ripples if we block out the Starlight with a giant circular screen we will also see ripples because the light is diffracting around the edges now for imagine imagine for a moment we put a giant screen in space that's a very special shape like this the star shape then we would actually get this image here this would be like dropping a pebble in a pond when instead of having ripples the area around the pebble is so perfectly smooth to one part in ten billion and that all the ripples are pushed out to the edges and that's what we actually want to do we want to put a giant screen in space and that's a very special shape but before I continue because the people who there are many ways to do to suppress starlight we call it blocking out starlight you actually could put this very special shape inside the telescope also that's a whole different story so I'm going to talk to you now about the star shade and this animation shows you a star shade and telescope launching together were the petals unfurl from their stowed position and a central truss would expand with those petals snapping into place now they have to be very precisely made so that the shape of the star shade and the flatness of it and just how it stays together is a challenge and the star shade actually would have to fly very far from the telescope tens of thousands of kilometers to block out that starlight just perfectly so we can find planets around it it's called the star shade and we actually the soonest the star shade actually is going strong and actually tomorrow I'll be going to San Diego to an optical engineering meeting where I'll be talking there about the star shade but just so you know that it's a real thing that with real hardware I want you to see this animation this is from August 2013 of four of the petals and these petals were stowed and now they're unfurling from their stowed position these are larger ons that actually snap into place rigid izing the pedal there's only four because that's all they could afford to do it's mostly the place where they attach that and it's the real thing they're checking actually know what they're checking is to make sure that those petals can deploy to position with respect to each other of millimeters and that they can do that over and over again no matter how many times it's deployed now you're seeing that second stage of deployment I always get asked why are there people in this movie but here the point was to show that not that it could deploy automatically and by the way later versions do deploy automatically but that there are the people but that the pedals deploy relative to each other in the same way each time now what I want you to know about this central truss is it was not built just for the starshade actually this is left over from constructing large radio deployables that have gone to space big things that are that the big inner disk is 15 meters even 20 meters in diameter and the star shade we want to build would be about 15 or 20 meters in diameter and later generations of this actually have smaller trusses that are more suitable for the star shade so the heritage from these comes from large things in space the pedals and how they still and deploy are what is new here's a myself and two of my team members Maggie Turnbull and Acura barish and here we're holding this giant pedal it has this long tip here if it looks dangerous that's because it is and it's a very special shape this particular pedal was made to demonstrate that that pedal could be made precisely to about a hundred and fifty microns so there's this real hardware development going on in the lab this is a pedal prototype it says use for manufacturing tolerance verification tests so if we can't go there no I really submit I really lost track of that if we can't go there why look we wanted to remote sensing we have big plans to build complicated space telescopes the starshade that would fly tens of thousands of kilometers from the telescope using let's say a two meter telescope is probably is most likely to be our very best option to find the true Earth's so to close I just want to leave you with a thought it's amazing to me that I've been working on exoplanets for twenty years when I first started working on exoplanets people didn't even exist they were didn't even believe that exoplanets existed even the professors at my own University where I was in grad school and the reason was because there were only a few and they were very close to the star and people didn't believe it because we thought that planets should be far from the star like Jupiter is and these big planets were found and people just thought the star was pulsating or there was something else going on and over the years people started believing it some people getting excited about it but most people had never heard of it you know you'd sort of meet someone on the airplane what do you work on well I work on the on exoplanets oh what's that and now it's like oh yeah I mean of course they know of course they heard about it you know in the New York Times or they read about it and so you get to this point where it's incredible but even now all of my students they of course they're exoplanets for children of course there are planets in the habitable zone actually they learn that from that eyes on exoplanets thing because they click and they can put habitable zones and so it's incredible now and so what my goal is and my my peers is we want to take that one next step actually and we want to be able to take our children and grandchildren nieces and nephews to a dark site and to point to a sun-like star and to say that star has a planet like Earth thank you okay thanks sounds like what you mean by like earth means alive like Earth is that correct well like Kurtis has a lot of different meanings what I personally mean is in Earth around a Sun and a planet that has oceans and continents and lush vegetation will you be able to detect atmospherically things like tectonic action and stuff okay that's a really hard question the funny thing was before we were saying someone suggested that our question to seduce a really hard ones okay plate tectonics is his problem we likely will not be able to detect any signs of plate tectonics or any gases of activity for sure right mmm I mean possibly okay for my any asks what do you think of the Drake Equation these days given what we're discovering okay and probably need to explain with the Drake Equation right well the Drake Equation was written by Frank Drake many decades ago and he used it as a tool to illustrate what are the chances for intelligent life out there and they're about six terms in the Drake Equation the first few are like how many stars form each year in the Milky Way and it kind of moves on to how long do you think an intelligent civilization could last and the Drake Equation is still useful but actually myself and others have reinvented the Drake Equation and we use it for our own purposes to say well what are the chances we're gonna find signs of life by way of gases in the planet atmosphere but just like the Drake Equation we can only really measure the first few terms the rest are very speculative and so we can always kind of tweak them in a favorable direction but we give ourselves about a 50/50 chance I'd say add your new equation to the presentation because that equation presumably will keep evolving until it's predictive and very nice be seeing how the terms right we find signs of if and when we find signs of life we could work back yes Tim raised asked how his Earth's bio signature fared over the billions of years they've been periods perhaps long ones when we would have looked pretty dead yes good question so oxygen for many for billions of years there was no sign of out there was no oxygen on our in our atmosphere or initially when oxygen was produced it reacted with rocks and it didn't accumulate in the atmosphere so for a long time yes our planet actually would have looked dead even when it had life well now there was a long period of microbial life that was not putting a lot of oxygen in the atmosphere right and that would have been undetectable things we don't know right now some people think that we had a period of time when we had methanogens methane producing bacteria and a huge amount of them and they would have produced methane that would have definitely been a bio signature if there was a huge amount of it but we don't know if our earth had that are there not planets in our own system that have a lot of methane that's presumably not biome genic yes so we have to get into a little more detail now but some planets okay let's put it like Jupiter itself has a lot of methane and any big planet that can hold on to hydrogen should have methane on it actually but a planet like Earth that is so it's gravity is relatively weak actually it's like when you're walking around with the heel I'm sure that's happened to almost everyone here but if you have the helium balloon and you were a child and you actually like let it go and it floated away light gases like hydrogen and helium they're not trapped here in our atmosphere but on planets where they do have hydrogen trapped if they're massive planets or cold planets then they should also have methane so we think we can sort through all the possibilities if we were to see a lot of methane that we could work through the options so you said there's research jamming ahead on looking for other bye or signature gases does this involve theorizing biology different than what we know so far that's a tough question and right now it does not unfortunately I know there's a lot of fans of like silicon-based life and other things but the reality is for astronomers you know we can only see what life does life generates gases it makes byproducts we can't see what the life is actually and there may be a future where we can put all that together but right now we're really just still struggling as to what we're even looking for so it's interesting you said that you're when you're when you finally able to get a spectrographic analysis of a an actual individual star figuring out whether that represents equilibrium is itself an issue for that I hadn't realized because you know Jim Lovelock figured out that Mars was in some kind of vehicle there briam therefore did but he was I guess knowing more than you guys know about exoplanets he was knowing more yeah Kevin Kelly yes what's the future of computational optical very large telescopes you know beyond phaser a and various things how our telescopes on some kind of Moore's Law curve of getting an insanely better every period of time well they're getting bigger and more expensive let me think I gotta think about how to answer that one I'm not totally sure what his question is specifically but you know we have this very right now the biggest telescope so don't say eight meters in diameter or ten meters in diameter optical telescopes on the ground and we actually think we've maxed out on the size we can make a monolithic mirror so the next generation telescopes they're 20 meters in diameter or 40 meters in diameter and they're composed of segments that are faced together some of them have small segments some have big segments that themselves are eight meters and so in that case you know these next telescopes it takes longer to make like the next step up and it's just harder actually and so it's not clear if beyond the next generation you can still keep making segmented mirrors and telescopes we may have to think of some whole new way to operate what's gonna cost for the starshade equip telesco okay I know you're gonna laugh because I'm going to give you a very specific number I get asking it because maybe somebody has it okay all right all right so if we just wanted to do the star shade itself that is I showed you just very briefly that we do have real hardware we're really pushing to working all the technology that itself would be including launch it would be about 650 million and that includes reserves of about 30% now that doesn't include the telescope but the good news is we're hoping that every telescope that is launched to space will be what we call star shade ready ready to work with the star shade so it would have a camera that could see the star shade the LED bank and the laser and and guide on it properly in the right kind of instrument to study the planet atmosphere once that goes and also have to have a radio communication to be able to communicate with the star shade to formation fly and there's the telescope being launched in 2024 called w first it's a two point four meter mirror same size as Hubble and that whole thing we hope is going to go far away from Earth's gravity where we can do formation of line so our plan right now is to get the star shade ready push it forward so that it we have a hope of actually going with w first say more about formation flying obviously you've got telescope and the star she a their calamity I said tens of thousands of kilometers and thousands of kilometers apart and we're talking about micron precision in the petals so this is manufacturing the petals well it's actually a 100 micron so that's a lot better than one micron but yes but well I can actually explain I can tell you about the formation of lineup but it's kind of cool actually so what's gonna happen at first I'll tell you how it will work and then I'll tell you the part that's really hard so essentially when you have this star shade and telescope every time it moves to a new star it has to realign so it'll take like a week or so for that star shade or telescope to fly across the sky and line up and first of all we know where this the star shaving telescope are because they're radio communicating to earth we can see the background stars where the star shade is the telescope can so that's how it knows where it is and then actually when it gets closer and closer to the star the telescope will see like a big LED Bank on the star shade no that is and as it's getting closer to the star a laser actually will be used to line it up precisely and what's the best the most clever thing that the engineers came up with is that once it's aligned properly you know how it stays aligned because some of that diffracted light at much longer wavelengths than are being used to study the planet is actually itself fused now when we think of formation flying we have had experience formation flying in Earth's gravity docking at the space station there's been a mission that went to the moon it was a four-month long mission called Grail and what it did was it did laser ranging so they weren't tightly formation flying but two spacecraft orbited the moon and they sent a laser back and forth and they could tell if they were closer or further it told them the precise gravity of the moon and so when we look at all these different situations in thinking that the star shade will be far away from Earth's gravity in a benign disturbance environment we're mostly left with what we call a sensing problem that is can you see that laser line that led Bank far away precisely enough to know exactly where it is to formation fly so the story is we do have heritage we've boiled it down to one specific thing that we're going to be working on did I convince you yes so the so the star seed is its own little spaceship that has capability of maneuvering and travelling some distance not enough I guess your are there herbal issues is it so far that that's not a big deal or is it having to deal with earth in the rest of the solar system well we want to get it far from Earth so we could either be in what we call a heliocentric earth trail earth lady in orbit or earth trail in orbit or far away at the so called Earth Sun LaGrant so has to be very far from Earth far from the gravity discovers they're now at one of them Al Gore camera is right which one I'll to the other side okay which is significantly farther I forget well it just depends you want to be in the earth and sun but we don't want to be seen like the sunlit part of Earth or having the Sun in the wrong location okay back to you a nice money question bill nigut yes what area of research work most effectively increased our capabilities search for earth-like and I'll say lifelike exoplanets in the next 10 - a large number of years if funding were not a limiting factor okay well if it's not limited at all then okay so I have to confess that with the whole tests and James Webb setup and even with this first the star shade is the first generation you know we still have to get really really lucky because anything we can conceive of now even the large 30 meter ground-based telescopes you only have a good shot at finding another earth but they may just find one you know or two and we think about our own earth there was this good question about well our earth wasn't oxygenated its whole life it looked at in the past or maybe we'll find a Venus instead of an earth we'd really really like in the future for someone to be able to launch a telescope that's so big and capable that it could literally find dozens of earths you know not just one or two that we're struggling and hoping to get in our you know next 10 or 20 years and so that would be very expensive very complicated we're like a ten billion dollar type of mission starshade all budgeted and paid for and coming you know the stars eat is not all budgeted not all paid for okay so so anything that's so new and on it and forefront you actually have to finish convincing yourself you know the rest of the world that you can actually do it and we have actually five specific problems we're working on one is the sensing problem we think they're all solvable one of them believe it or not is that that star shade if the edges the edges of those petals they have to be as sharp as a razor if they're not actually sunlight will will you know Bend around them and scatter off those edges actually and get into the image because remember we're trying to block out the Starlight to one are in 10 billion so even things like our own Sun or anything coming by maybe even Venus or something very bright so figuring that out so we have the sort of list of things and first we'd like to knock all those things sound and that's about a twenty million dollar price tag on that and then to get it fully ready so that we've tested everything we can think of and we've demoed it all and we've done also ongoing or sub scale tests like the small star shades in the lab to show that you can really block the star light out like you expect it to getting it that far is more like 150 million and then the rest of the costs is just for building the spacecraft and the launch and things that people know how to do already okay so somebody who says okay I want I wanted to discover if there's life of the sequence of events is 20 million 150 million and then what for the we're like four hundred million for the wrestler blinders hey this is like the biggest cosmic question we got yeah the answer of or absolutely alone sorry folks be very careful would be huge the answer of there's other life or even lots of other life changes everything so when we say key concern 570 million there's just do it yo there's I just finished reading the Martian I'm gonna see the movie with Matt Damon when it comes out shortly interstellar was wonderful gravity was wonderful interest in serious engaging of space is with us still even though we're supposed to have lost interest what happened I say Italy I got distracted because I was reading this question I was thinking that answered well combine like that one I like that question so your question was interest is still there so maybe it's just because Hollywood loves to try to simulate zero-g but something keeps people excited about prospects of space you know the Star Trek it's a long time ago though I'm not the round of that coming along and these realistic space exploration by humans films keep coming along and so I would have to say NASA's funding is not keeping up with the public interest well I think there's a few things going on one is that I really do believe we are born explorers and maybe it was so in the past when people were you know sport Antarctica for the first time and everything we don't have that now we think of our oceans are not fully explored but arguably all of land is and I feel like space is really the place where we can still dream of exploring it's still where things are unknown and so that's a big thing but also you know I think in terms of the NASA and funding I mean one point is that things are just you know you pick the low-hanging fruit you do the easy things you have your backyard telescope but eventually you know you're going for the 30 meter telescope the big telescopes in space things the harder things are just more expensive is there low-hanging fruit with your search and high hanging fruit that I mean what's the difference well oh hang what can you get in the next few years and what will it take a lot longer to get okay well I'd say in the next few years the test spacecraft will launch the one with the four cameras and we'll find the pool of rocky planets that we will follow up to look at their atmospheres with the James Webb Space Telescope that's a telescope launched in 2018 you know if we're lucky we may find something but the chance of us really finding science of life is small on that one we hope to launch the star shade without one we can find a few earths and look at their spectra for life so in the next 10 or 20 years that's what we have to look forward to you probably won't be surprised by a question probably often get is there any science fiction or reading in your personal background let's see No well so what I would have to admit that my favorite science fiction author although this was really more from about 20 years ago was Robert Heinlein and I read all of his books many years after so they weren't totally contemporary because when he had written them you know he predicted many things like the ATM and other things like personal robots are only now just maybe coming but I just loved reading those and I read like everyone I love time travel books recently I started to read a new generation or let's say genre of science fiction including the Martian and other sort of more realistic things about going to Mars but I'd have to say it was really mostly just Heinlein a little bit about the students you're getting these days do you deal with students are you dealing strictly with the research scenes okay well there's sort of two different types of students now and unfortunately one of them I really hate to say anything negative but unfortunately that's the first thing that comes to mind but I think it just speaks to anyone who is a parent or you know will be or it's a grandparent or an uncle or an aunt but there's a sort of sense of entitlement that I see amongst of my students which is not it's not helpful people who are yeah and I actually don't know what to do about it so I I'm still sort of sorting through the edelman yes because I think it's it must have come from like when everyone gets praised when they don't deserve it or you know there's like no sense of like I don't they just expect that they deserve everything and it just it's not a good way to kind of go through through life actually so there's sort of that sad but there's the other set who just stick with that for me how do you fix it how do you fix there you've got a student figures like they're already halfway there what do you do I don't know how to fix that part I don't know if that problems fixable I'll take that student well sometimes you don't find this stuff out until you know time goes by actually so I've had to regroup and think through it a little a little more now okay moving from unfortunately to fortunately what you know the fortunate students are just tremendously incredible and we had a great summer with the set I hope they're watching this but I had a set of summer students and it's part of a project where well we wanted to try to understand what kinds of gases could be bio signatures but given that life on Earth literally have produces thousands of maybe let's say a thousands thousands of gases how would you go about this well some other colleagues and I had made a long list of what we thought was all molecules that could be in gas form and so what I had the students do was see are their spectra for these molecules and we would get together and work and they're just so hard-working and they have a great sense of humor and we just wrote a lot of code and searched through like online databases and one of the students made a GUI like a nice user interface we can look at all the spectra and compare them and so some students are just so like thirsty to work on a problem and the ones who are really end up being suited for science I mean unfortunately that image of you know the MIT student and professor just always working and always tech coding it's it's true in a lot of cases but it's that same desire when you get stuck on a problem it's almost like reading a mystery novel and you know you can't put it down because you have to get to the end it's like that and so the best students are ones where we're on the same wavelength you know we're in sync and we have a problem that we love working on and that we can work on together that's the best case are the spectral lines to a cold front offer lines they aren't really called Fraunhofer lines and I believe that specifically refers to a set of lines in the sun's photosphere that were discovered by Fraunhofer I once handled the original slides that found hard from a long glass slides I broke several of them by accident that's my contribution to astronaut back to students jr. asked how would you advise curious students to prepare for a career in XO planetary science okay well one thing is it seems like we can't get away from computers and programming and I'd say programming now isn't always what it used to be because before we honestly coded every single thing from scratch and we sometimes we had like a library of functions we could draw on but now it's really oh it's really um I was gonna say something funny but just in case one of the students was watching it I didn't I didn't want to say it but now we really love using really well we really love using Python I don't know if anyone here yeah right because what happens is before we had MIT was really big on MATLAB and other things because they provide a life you know there's like a license for students and the sort of secret is they also have a help desk so if the student got stuck most of them don't know this so you could actually no email MATLAB and they would help you out but the problem is you can't get inside of it and it can be very slow and it's not flexible but now with Python everybody's writing their own i'm code that you can download it's often very hard to install because you have libraries and problems with like what your computer has versus what they're they think you have but the downside of that so the great side is there's a huge power in it because anything that you want or some complicated code that would take you let's say six months to write it's already there the downside is it breeds a mentality where you really just write like what we call a giant wrapper and you just use things without thinking and so I've seen a lot of a lot of that also but you knowing how to use code and to write code and not just to use things as what we call black boxes I mean that may be sound a little strange of something to suggest but I think really that's your main thing to the main tool for so many disciplines today there's lots of people are coming with code training so does that yeah I already covers that part of chemistry is trying to meet many things like that I'd say physics mostly I mean astronomy is really applied physics it's great to maintain interest but really just trying to understand the nuts and bolts is what's really important very fiddler ask the question that you noticed how does your work intersect Lacetti that's at all right SETI search for extraterrestrial intelligence well SETI does intersect now because SETI in addition to doing these surveys of the sky and of stars everywhere SETI can now actually focus in part on stars with no planets it's like that kepler-452b 6 and those systems now that I would say is mostly how SETI intersects and said you just got a bunch of money that suggests that what you're doing also should get that kind of money yes well I do I don't answer no because it just suggests this as you already pointed out this you know increase in interests in space and the fact that these planets are out there people are excited people want to accelerate our opportunity to find signs of life intelligent or otherwise so yeah and elia what's the best neighborhood for exoplanet she showed us that wonderful image of where Kepler is looking at as a rather small sample of a rather large galaxy right well I think for now the best neighborhood really are those stars that are closest to our Sun and they're still quite far away actually there's about a hundred stars like our Sun within about 30 light years but really it's our solar neighborhood we want to find things that are close because they're bright and they're easier to study and again because someday we hope we might find a way to go there so there's no particular preference of like looking you know toward the center of the galaxy you're away from the center of the galaxy or anything like that I mean not really for me personally but the reason why Kepler Kepler heard a very specific reason for being where it is I mean towards the center of the galaxy it's so densely populated with stars it's very hard to see what's going on and if you would look outside the galaxy Kepler wouldn't have had enough stars to find transits because remember they have the planets have to be specially aligned so you can each different technique or each method has its own special place in the galaxy so Kevin Kelley is is there an emerging sort of taxonomy as it's been quite awhile now a taxonomy of stars and you referred to it a lot is there a taxonomy of planet well when you ask that question it's funny because we actually have you know earth it's not too inventive right earth super earth mini Neptune Neptune you know Jupiter you know so actually no actually and people fight actually about what we should call things and everybody uses different names but I think one thing instead of the taxonomy yet is what's going on and I'll just add it in here but we are starting to think that planets about 1.6 1.7 times the size of Earth are smaller appeared to be predominantly rocky and planets bigger than about that appear to have like a gas envelope and be of much lower density than could be predominately rocky have no life we assume we have no life because we think that gas envelope just isn't favorable for life yeah so you got a theory of life that might function on a gas planet I can't think of really any great theory but Carl Sagan himself wrote a paper actually about Jupiter and the question is what's really interesting actually better own earth is that we have bacteria floating around in our atmosphere on aerosols little particles and so the thought was well maybe in Jupiter you could have little air cells and there's life floating around and the reason we don't like that theory is because Jupiter has these giant convective cells and any life if it's floating around it'll be brought down to where it's actually quite hot in Jupiter and so there's no really theory for life on on a gas planet a planet with a lot of gas yet in this local solar system the only one we know well the gas planet some of them have pretty significantly interesting satellites run their moons around them that may be potential places for life is that also an issue and exoplanets well the issue is that the exoplanets I think I explained we're so hard to find and see and so the moons are gonna be even more hard right to find in C so we don't rule them out for any really good reason only because they're hard to see and any moon without an atmosphere like your rope are something that may have subsurface oceans we can't see subsurface life in any way so we expect them to be out there in fact our the our moods of the Gale so we're detecting gas planets were even sort of getting imaging of them are their moons potentially detectable perhaps by their own transiting or things like yes actually so just FYI so exoplanets are often in the news and we always say that exoplanets have always delivered we've gotten everything we wanted on our wish list except for one thing and that is exoplanet moons and everyone was hoping that the Kepler data would show exoplanet moons around giant planets either by transit or other ways but we haven't seen them but they'd have to be big moons big like half the size of Earth or bigger from a distance would we detect the moon said that we have around Saturn no problem none of our solar system moons would be discoverable okay so it's another couple levels of resolution before you can get that so you mentioned the newsworthy and problematic issue there being more rocky planets and fewer big-ass planets than were expected by theory which is fantastic and so where are you and others going with Theory given that little problem we're mean others going so okay the you know the theory was there to be lots of gas lines knots many rocket planets and then the reality is theirs doesn't match that yeah no I know you're a lot the funny thing is is when I tell my students it's not totally true now but when they do their PhD defense and they get asked like everything possible I say like look every day is like a PhD defense because they get asked all sorts of things even things that I myself aren't working on but what I think will end up that anyway we can think of for why there are so many of these small planets is probably it's all of the above and so people think of things like well perhaps some of these planets have moved in close to the star and have just lost their atmosphere they were may be formed bigger maybe like a Neptune and started losing atmosphere because of solar wind or being heated and that might account for some of them but not all of them we think the gas giants have a solid core but we're not a hundred percent sure including our including Jupiter were not 100 percent sure let me finish the the and in other people think well perhaps this is when the planet forms like Jupiter we think it formed and got big and it got so massive that it sucked in everything around it and it became dominant but some people said well what about if seen an inner planetary system lots of them formed almost at the same time and no one could dominate over the other well they would all exhaust their feeding zone and be dwarfed like they wouldn't take over what the other one had because they all kind of grew up together and and so there's these variety of thinking but it's not really clear yet which one it will be she showed us one planet with two suns and presumably a complicated orbit it wasn't necessarily complex really but the stars are orbiting each other and the planet is orbiting the outer and I like to say sunsets there have got to be pretty exciting one of the things Carl Sagan did and you got a glimpse of it in this long short at the beginning as he he described amazing places that were you know already identifiable I don't know of a planet made of diamonds and you go out its various things well I want to go there the exoticness of the kinds of places that are out there seems to be intriguingly in one increasing and increasingly ever more detail is that what you're perceiving do you mean out there for exoplanets or out there anywhere exoplanets well yeah let's hey sorry not just explodes everywhere go on yeah well with exoplanets it's really convoluted to describe our models and how we you know how we really interpret the data and see things and so just describing what they're like is a really kind of a tool to communicate what we think it could be but it's probably all of the above you know we imagine that one planet could be red red vegetation another one would have green or some other color even the variety frankly shocks me I mean this is just sort of mechanics and chemistry not even big life big life makes a lot of variety that's evolution in Darwin that big on life it has much variety is pretty strange and exciting in its own right so whether or not there's things living there once we become the things living there these will be exotic places they will but I also hope that all those planets and all those orbits brings you some you know or everyone some reassurance because before you know earth is definitely very special but I think we have some sense now that it is also somewhat random because we see all these planets and all these different orbits all different sizes and masses and so earth happened to be just right and surely there should be other planets also out there that are also just right different kinds of just right the do you want to go any of these places or you just wanted to find out if there's something pulsing there for me I just I'm not one of those people who would volunteer to go to alpha cen so there's a pulse of the places and this is part of the SETI story is there a pull toward other life it's most of it's not going to be intelligent there's going to be microbes and do we really want to go visit microbes somewhere the answer is yes probably because if they can handle microbes that can handle other things we might be interesting it like if you come to microbial life to microbial earth back when this was a cool place to you start an oxygen regime right yeah we've been cool but don't forget back in the in the time of the dinosaurs they couldn't have communicated with us either they didn't so you're right they didn't believe their DNA we're discovering all they left is a pattern of how their bones looked so the lack of communication does seem to be the norm but the lack of life is not necessarily the norm it sounds like and on that note what is clear from what we've heard from Sara Seager tonight is that there's a lot happening in this century with this kind of discovery and we're going to know a lot more about life in the galaxy thanks to you and the people you're working with thank you for coming [Applause] [Music] you [Music]

Channel: Long Now Foundation

Views: 28,197

Keywords: Space, Science, Technology, exoplanets, planetary science, telescope, starshade, atmosphere, Kepler, astrophysics, habitable range, spectrographic

Id: i5ts9VpQA1g

Length: 86min 38sec (5198 seconds)

Published: Tue Apr 28 2020