Kepler, Exoplanets and SETI - Geoff Marcy (SETI Talks)

okay welcome along ladies and gentlement your weekly City seminar series today we're very fortunate to be losing our screen on the right hand side there we go to be joined by Jeff Marcy professor Jeffrey mercy from UC Berkeley he jeff attended UCLA for his BA in physics and astronomy and then I did a PhD at Santa Cruz University of Santa Cruz use diversity of California Santa Cruz and after that he went to Carnegie Institute of Washington to be a Carnegie fellow for a couple of years and then he returned to the Bay Area and was on the staff at the San Francisco State University in 99 he moved to Berkeley Jeff is the very well-known scientist who has accomplished a great deal in his career particularly regarding exoplanets he discovered seventy of the first x100 exoplanets that were found he has a numerous awards including california scientist of the year in 2000 he has a Harry Draper medal from the National Academy of Sciences the Beatrice Tinsley prize from the American Astronomical Society he has a member of the National Academy of Sciences and the Shore Prize has presented many lectures in in his career including those that achieved the Carl Sagan prize for science popularization today Jeff is going to talk to us about his latest work and give us a hint about what he's up to now and he's going to talk to us about the search for earth-like planets and also it's linked to intelligent life in the universe so if you'll join me in welcoming Jeff I may be a bit loud and did you buy it yeah well I'm moved to be here tonight because I think this is a special moment not just this year but I think it's a special moment in human history and that may sound like an over-the-top comment I'll try to explain to you why I think in the realm of science and actually in the human exploration of our universe we are at a special moment and indeed I think it's fair to say that in science occasionally questions that have puzzled humans for thousands of years suddenly come up on the horizon and you can almost taste the answer the cure for penicillin the cure for for bacterial diseases that required penicillin was one such quest that we humans eventually solved Armstrong step on the moon you knew it was going to happen a a year two beforehand the the solving of the human genome we knew could see it coming over the horizon and we have a similar quest that's been going on for over 2,000 years and that is solving the question of whether there are other earth-like planets elsewhere in the universe how common are earth-like planets and is there in any life on those planets questions that Aristotle and his philosophical friends pondered in the suburbs of Athens somewhat behind closed doors now here over 2,000 years later we're really poised to answer the questions that that represent the title of my talk and so I'm going to try to give you a feeling for how close we are to answering these epochal questions and I'll start with some acknowledgments because I'll be representing a group of over a hundred scientists some funded by NASA I have close collaborators you see named here Andrew Howard John Johnson Deborah Fisher Howard Isaacs and Jason Wright the Ken and Gloria levy have been very generous allowing the research to happen without the generous donations of few people we couldn't do our research the nasa kepler team is going to play a crucial role there's about a hundred scientists and engineers and i'll be trying to represent the work that they've done leaders bill Baruch E and Dave Koch Ball Aerospace built the space for in telescope I'll be telling you about and they're a group of wonderful scientists and friends some of whom are named here that work on Kepler with me I've pointed out a few of them who are really leading the charge with Kepler Ted Dunham Nick go tier John Jenkins who's in the audience here Doug called well Steve Bryson Natalie batalha and and many others making that the Kepler mission happen and the main point is that that science these days is quite a group effort and we couldn't solve a question like the one you see here is anybody out there without a joint effort of a large number of people so it is in fact the case that here in 2011 we still don't know of any life elsewhere in the universe except for right here on the planet Earth it's almost embarrassing saying that after 40 years of science fiction on TV in the form of Star Trek and and Star Wars in the movies we still don't know of any life elsewhere except for right on our own home planet and of course this is not for lack of trying NASA and now in Europe ISA are exploring the the planets and the moons in our solar system hunting for life either microbial or perhaps even larger Mars is an obvious destination the moons of Jupiter and Saturn are excellent destinations many of them have a lot of water and so there's clearly a great quest for Humanity in the upcoming decade or two hunting for life within our solar system but I can tell you the the sort of sobering news right off the bat there is no other intelligent life elsewhere in our solar system the satellites we've already sent to all the planets show that there are no smart critters with big brains walking on the surface of Venus or mercury or Mars so that the quest for for other intelligent beings really takes us out of the solar system and into the Milky Way galaxy with its 200 billion stars and the hunt is now on for earth-like planets in our Milky Way galaxy orbiting other stars that might be suitable for life as we know it now we do have some advanced notions as to whether earth-like planets should be common or rare and those notions come from studying the infant stars that we see literally being born out of the gas and dust in our Milky Way galaxy and here you see a picture of the Orion Nebula a very famous star forming region it is a mere 1 million years old and within it young stars are condensing out of the gas and dust that make up the Orion Nebula the the middle star and the sword of the Orion constellation and in fact if you zoom in closely to those young stars you'll see that the young stars are usually accompanied by some thin flattened opaque material that blocks the middle of the star sometimes you see the opaque material surrounding the star and that is a platter of gas and dust the placental material out of which the star formed but within which planets can form including the large ones the size of Jupiter gaseous ones and small ones the size of the earth that might be rocky there's plenty of building block material in these protoplanetary discs and so the the cartoon that you should take away from this introduction is that we already know that around young stars as they form there's also material around the young stars within which the Comets the asteroids and the planets themselves can form in a growth sequence that you see at the bottom with the small pebbles colliding sticking and growing into ever larger bodies eventually the size of planets so the the search is clearly warranted to hunt for earth sized and maybe even earth-like planets around other stars and the best way to do it it turns out is with a spaceborne telescope called Kepler and here's how it works as an unseen earth-sized planet crosses in front of a star it will block a small fraction of the Starlight and so the star will dim you can't see the stars disk you certainly can't see the planet it's lost in the glare of the host star but you can monitor the brightness of the star minute after minute after minute hoping to make a graph of brightness versus time seeing the star dim simply due to this crossing earth-sized planet you need to be above the Earth's atmosphere to do this photometry as it's called and the reason is is that the Earth's atmosphere causes stars to shimmer and fluctuate in their brightness and so only with a spaceborne telescope like Kepler can you measure the bright is precisely enough to detect a tiny planet the size of the earth in the face of its enormous host star so here's Kepler we had hopes to launch it two years ago in March of 2009 you see it here on the launch pad and I think the next slide might be the the launch in March - ten nine eight seven six five four three two engines start one zero and liftoff of the Delta two rocket with Kepler on a search for planets in some way like are powered by solid rocket booster white you can see the solid rocket boosters the telescope is up at the nose cone up here 34 seconds Mach one vehicle is now going supersonic beginning to trail off as we're passing 45 seconds chamber pressure good steady state value it symmetrical burn on the ground with solids coming up five seconds for burnout and we have ignition of the airless solid motors it's it's really worth remembering that we are indeed living in a special time and which launches like this almost always succeed we almost take them for granted and it's a tribute to our civilization and our species that we're able to send machines out into space position them precisely sort of without much more trouble than you know making your breakfast in the morning it's it's a marvelous we should be applauding ourselves that we have NASA that NASA can do these things born of all the work of the engineers and scientist scientists that made it possible Kepler is itself an amazing telescope the mirror is one metre in diameter Hubble for comparison is 2.4 meters so it's a little smaller than Hubble but what's special about Kepler allows it to do things that Hubble can't even dream of doing namely it has an enormous field of view 10 degrees by 10 degrees that's 20 full moons by 20 full moons it at the back of it it has a ninety five megapixel camera so that it can take pictures of the full 10 degrees by 10 degrees and what that allows Kepler to do is monitor the brightness of a hundred and fifty thousand stars minute after minute after minute after minute already in my talk this this evening Kepler has taken six or seven snapshots and it will continue to do so during the talk what's remarkable is that it Co adds those pictures into 30 minute bins so every 30 minutes we get a new measure of the brightness of each star good to a few parts per million quite remarkable and it's supposed to do this for three and a half years hopefully six or seven years if we get a little more money which is what we're we're hoping for and the truly remarkable capability of Kepler that blows everything else out of the water is that it measures the brightnesses of stars to 1/100 of 1% of the brightness of the star so if the star should dim by even one part in 10,000 Kepler will catch that and that's exactly the amount by which a star dims when an earth-sized planet crosses in front it's just the area of the planet blocking the area of the star and that ratio is one ten thousandth so Kepler has a remarkable and frankly unprecedented ability to detect earth sized planets around regular stars that it's scaring at and it is indeed staring at a patch of the sky continuously near the constellation cygnus there's Lyra there's Cygnus obviously a swan in the night sky and indeed if you walk out tonight at the end of the talk if you look more or less straight up you'll see a very bright star that's Vega and right next to it is the constellation Cygnus the northern cross it's right overhead this time of the year and indeed that's why tonight I'll be going back after this talk to use the Keck telescope in Hawaii which we operate from UC Berkeley to do follow-up observations of kepler stars because it's up right now over overhead at night here's the field of view of kepler 10 degrees by 10 degrees you can see the the many CCD detectors 42 of them which we use to take these pictures and one of the most special stars that we noticed very early on is called Kepler 10 and I want to introduce to you this star Kepler 10 because the data we took on it with Kepler and the follow-up data tells an extraordinary story so I'm going to zoom in on the Kepler field near Kepler 10 there's Cygnus there's that Swan there's the Kepler field of view we haven't stared anywhere else for now over two years and now I'll zoom in on Kepler 10 and I would like to invite you to notice how many stars there are in the field of view of Kepler indeed over 150,000 stars are being monitored and there's Kepler 10 so out of all those stars this one caught our attention and now I want to show you why and I'm going to show you some technical plots I hope you don't mind I'm going to show you the real science that the Kepler science team looks at and writes a computer code to analyze and if you look carefully at this graph you'll see it's a graph of the brightness of the star Kepler 10 over the course of time about 205 the days are shown here and if you look carefully and I'll invite all of you to make the discovery for yourself you'll see something remarkable first on the y-axis look at this thank you that would be great that's wonderful on the y-axis we've put the average brightness of the star to be 1 but look at the number on the y-axis 0.999 5 of 1 so you're only seeing brightness fluctuations of a few parts per 10,000 in the scatter of the points up and down but if you look carefully you'll see that there are brief moments when the star dims and then returns back to full brightness quite quickly and I'll let you look and this would be a signature of a planet crossing in front of the star as it orbits the star repeatedly crossing in front of the star so if you think you've seen the planet let me now reveal to you where it is right there I'll uncover it you notice how it it dims and then dims again and dims again and dims again and the amount of dimming you can read off with your eye it goes down to 0.99 9 well 5 roughly speaking so this is a planet that blocks something like five ten thousandth of the area of the star so it's a quite small planet in fact you can show that it's only a couple three times bigger than the earth so it's a very small planet quite special because of its small size but that's not why I'm showing you these data there's something else in here that you can only see if you zoom in if you zoom into a little piece of data right there here's the zoom in there's what we had been looking at and now down in the lower right is the zoomed in and now you see one of the dimming ziz shown in in the blue but now if you look carefully you might be able to see another planet that we hadn't already mentioned and noticed so if you look carefully you'll see a dimming and then another dim and then another one and another one another one no more than about one part in 10,000 0.0001 on this scale let me now reveal to you that planet there so you can see by eye the planets in the kepler photometry it's extraordinary that you can literally look at the data and see the planets because every time the planet crosses in front it blocks a little of the Starlight you know the orbital period of the planet by looking at the data by eye you can see that in this case you're only seeing ten days of data and so something like every day or so the planet crosses in front this planet has an orbital period one year is just about a day or so in fact it's 0.84 days is the orbital period this is a planet hugging very close to its star whipping around the star very quickly taking less than a day something like 20 hours to go around the star and if you take all of those dimming and you plot them on top of each other here's what the dimming looks like you see there's the brightness of the star and then there's a dimming in the middle and then constant brightness again and the point is that you can see how beautiful these Kepler data are you wouldn't normally think of raw data like this being aesthetically pleasing but I find this gorgeous and and you can see why this beautiful dimming you can smell the planet crossing in front of the star and then the planet you know crosses over the star and then the planet emerges from the star with that slope there you can you can just almost visualize the planet just by looking at the brightness data it's amazing now there's more of course the amount of dimming tells you how big the planet is and in this case the dimming as I say is 0.0001 v of the normal brightness one point five parts per 10,000 and that immediately tells you the size of the planet turns out to be 40% bigger than the earth one point for Earth radii and by the way that is the world's record this is the smallest planet ever found still to this day validated confirmed around another sun-like star this is the smallest one it's not exactly the size of the earth but it is obviously tantalizingly close to a planet that has the same size or nearly the same size as our own planet Earth that's amazing in and of itself but there's more and and I'll show you a little bit more here is the summary so far we watched a planet cross in front of the star by measuring the brightness of the star as seen in the lower graph but we can also make Doppler measurements of the star the host star itself why in the world would you want to make Doppler measurements measure the Doppler shift of the light waves well the reason is if you measure Doppler shifts of the star you can tell whether the star is coming at you or going away from you you all know the Doppler shift for those of you or not big-time scientists who you know that the train whistle changes its pitch when the train goes by you so even with your eyes closed you can tell the Doppler shift is sending a signal to your brain that the train is either approaching or receding and so it is with light waves from a star you can tell whether a star is approaching us at the earth or receding why would a star wobble around like that well because it's being yanked on gravitationally by this supposed planet as the planet goes around the star it pulls on the star gravitationally and you see the star respond for every action there's an equal and opposite reaction so we should see the Doppler shift varied just like a sort of a police officer monitoring the the speed of the star with a radar gun and here's in fact the graph of the speed of the star over the course of time and you can see the star did change its velocity upward and then downward and then upward again this star indeed is being yanked around by its little planet even though it's only one point four Earth radii just as you would have predicted and that tells us the mass of the planet because of course the more massive the planet the more strongly Yanks gravitationally on the star and you can use Newton's laws of physics and you get what 4.5 times the mass of the earth bulk mass of the earth so now we know two things about this planet its size in radius and its mass based on the Doppler measurements and if you put those two together you can determine therefore the density of the planet remember mass of an object divided by the volume of an object is density and in this case we get eight point eight grams per cubic centimeter eight point eight grams per cubic centimeter well at first that doesn't mean a thing to me but if you think back to your high school chemistry days can you remember your high school chem my high school chemistry teacher said remember one thing water has a density of one one gram per cubic about all I can remember from high school chemistry but that's pretty good because this planet has eight point eight times that density and indeed the planet Earth our planet Earth has a density of five and 1/2 grams per cubic centimeter so this is a planet slightly more dense even than our planet Earth and so it's surely a solid planet indeed a planet made of material that's slightly more dense than our solid planet Earth in is a rocky planet the first definitively rocky planet I would suggest ever found around a sun-like star we've depicted it as seen here a solid planet we know it's mass radius and density we've given it a little reddish tinge because perhaps the higher density is partly due to a higher-than-average admixture of iron and nickel that the heavier elements that would give it the higher density and we've even are constructed a movie or at least NASA has so here's a little animated movie of what we think the star and it's planet looks like there you see the planet in silhouette the thing that blocked one part in 10,000 of the light of the star one side of the planet is blow-torched by the star because remember this planet is so close to its star it's very hot about 1,500 degrees Celsius and on the backside its frigid cold because the backside of the planet is just looking out into the black cold darkness of the universe and then nASA has put in some white flecks of snow for reasons I have no idea it's about one fiftieth the size of the Earth's orbit one fiftieth the Earth's orbit around the Sun and you can see that the animators at NASA have watched too much star wars but it's a solid surface for sure maybe it has plate tectonics maybe volcanism because it's so hot on the surface it would be extraordinarily wonderful to someday send a spacecraft and get close-up pictures to find out what such a scorched rocky world might actually be like so that's what we think kepler-10 looks like but kepler the spacecraft has found much much more and with that as the backdrop let me now show you some of the highlights just in the last few months that Kepler has announced one of them is that we've announced over 1200 planet candidates we call them conservatively candidates because we haven't verified that they really are planets in most cases but I can promise you that 90 to 95% of them really are planets a few of them are false positives which is normal for a science experiment if you plot up a histogram of their sizes which I'll show you in a minute most of the planets are nearly the size of the earth this is utterly unprecedented extraordinary information for the first time in human history we know that small earth sized planets are far more common than the larger planets I'll tell you about that in a moment and we have found many indeed over a hundred and seventy stars that have two or three or four planets or more even and I'll be telling you a little bit about that as well so here's sort of the summary remember that out of 150,000 stars we've been monitoring for planets around any of them and here they are every yellow dot in the field of view is a Kepler star for which we've already found at least one planet and in this pot I've color-coded them so the blue dots are the planets that are nearly earth sized look at all the blue dots there are plausibly earth-sized planets the green are planets a little bigger than Earth 1.25 22.0 earth sizes a lot of green dots the universe is just overflowing with planets of nearly the size of the earth and then the orange dots are neptune-sized the red dots represent the the gaseous giant planets like Jupiter and Saturn and there's plenty of those too so the universe is filled with a diversity of planet types from small nearly earth sized ones up to Jupiter's and even super Jupiter's and here's another depiction of them remember each one of these planets was discovered by the dimming of its host star as the planet crossed in front so we know what kind of an orbit the planet is in what its orbital period is and what its size is and so we've depicted it in this graphic that you see here with all of the stars we even know of course the size of the host star and the colors of the host star from the measurements we've been making so you can see the different sizes and colors of the stars and the sizes of the planets that are going around them it's an incredible avalanche of planetary information utterly unprecedented we've never had anything like this magnitude or quality of information about planets around other stars now with a little apologies I can't help but show you some fairly couple of geeky plots that are precious so I hope you'll bear with me this is a graph that shows the occurrence rate how many planets we found for different sizes of planet some of the planets are smaller some of them and on the x-axis I have the size of the planet in Earth units from the size of the earth at the far left 1.0 all the way up to 22 times the size of the earth but the graph shows how many planets we found at each one of those sizes and the takeaway message here is that the big planets that are roughly 10 times the size of the earth like Jupiter they're rare there are Jupiter's out there there are Saturn's but they're far rarer then are the smaller planets of one or two times the size of the earth and you can see the graph you can see some error bars the take-home message is utterly profound when you look up into the night sky at the twinkling lights as you will when you walk out of here tonight there are far more of the nearly earth sized planets than there are of the giant Jupiter sized planets the the galaxy is teeming with the small ones and moreover you can ask how many planets are there four stars of different sizes let me say that again how many planets are there as a function of the Stars size the host stars size and so you see on the x-axis stars the size of the Sun I gave that a 1.0 right in the middle is the solar size but the stars that are bigger than the Sun have fewer planets and in contrast at the left the stars smaller than the Sun have more planets and in particular more of these small planets the ones that are 2 to 4 Earth radii so in fact what we're learning is something we hadn't even imagined which is that stars smaller than the Sun have more of the small planets the size of the earth or nearly so then do the bigger planets so this is an amazing clue because most of you probably know that our Milky Way galaxy has more of the smaller stars than the bigger stars so this very popular numerous type of star the smaller stars are the ones have more of the smaller planets it's an amazing result it's so amazing that we want to check it it looks convincing here but it's so remarkable that in the next year or two we will take more measurements with Kepler and try to verify this now in addition Kepler has been finding stars that have more than one planet orbiting the star and by the way by more than one planet I mean more than one planet that crosses in front of the star transiting the star dimming the star so that we can detect it with Kepler and the Prize winner so far is Kepler 11 and you see an artist's rendering of it here six different planets all cross in front of the star here's the depiction of the Kepler 11 system there's the six planets always hiding in a nearly flattened plane and here's our solar system for comparison Mercury and Venus you see these are six planets compactified within a realm no bigger than Venus's orbit around the Sun an amazing compact six planet system and here's an animation showing what it looks like you see the star dimming at odd times as planets cross in front of it it's like some sort of a NASCAR auto race or something who's winning we've not detected any moons yet nor rings we're looking though so this is amazing but this is just one example of a multi planet system that Kepler has found there's another one here here's a star with two planets quite remarkable I wanted to point this out to you this is a special treat these two planets are not only gravitationally yanking on the host star and vice versa but the two planets yank gravitationally on each other and so as the planets go around the star they lead or lag depending on how they've yanked themselves so the idea is this that if you have a star with a single that the planet of course goes around the star like clockwork you could set your watch by when it is that a planet crosses in front of the star there and then again right there planets orbiting obeying Newton's laws of physics will orbit with exactly the same duration of every orbit but what if instead the star has two planets orbiting it if there are two planets then the planets will yank gravitationally on each other sometimes holding one of them back or maybe yanking one of them forward so that they arrived a little late or a little early and we're detecting these lead and lags in the arrival of the planet with Kepler see there's one that came a little early and now here comes the planet again a little late and then again a little early and the reason is the planets are literally yanking on each other varying the orbital period and we detect this very clearly with Kepler so we're actually seeing the presence and then able to measure the masses of other planets in the system because of their effects on each other this is an utterly new technique we call it transit timing variations and it's really going to transform how we study the architectures of multi-planet systems but meanwhile we're detecting a lot of stars that have multiple planets and here they all are from Kepler there are now 170 stars that show two or more planets that transit that dim the star never mind the other planets that are out of the plane that don't transit and you can see them all here in these graphs this is real data you're seeing the stars at the center it's we left it dark but you're seeing the size of the orbit and the relative size of the planets by the size of the dots and moreover we know exactly when a planet crosses in front of its star and so we know that ticking clock we can predict in the future where a law in orbit every one of those planets must be even in the future because we can predict based on what we've seen so far so we know the orbital period and exactly where they are what we call the orbital phase around in their circles so it's an amazing sort of menagerie a clockwork and let me now show you where all the planets will be in the future this is actually science this is not laughable it's an incredible thing this is an actual prediction with very high accuracy of exactly where each of the planets is around each of the stars some of them are very close in orbiting very quickly they look silly others are in quite slow wide orbits way out here like this but this is the kind of is sort of flood of planetary information and you might even call it architectural information because for each one of these systems were learning their structure and the sizes of the planets it's an amazing flood and you can see now why Kepler has transformed the field of planetary science just in the last few months now to summarize so far Kepler is finding planets nearly the size of the earth and there are the more of those smaller planets this is I think a historic result but I'd like to move on to the second portion of my talk on something that's more speculative and that is what about planets that are suitable for life what fraction of the planets have the right conditions for biology and what do we what are those conditions what are the the sorts of environmental factors that render a planet habitable well we we know one factor that really does matter and that's temperature if you're earth-sized planet is too close to its host star the host star will warm up the planet too much and it will be too hot any water on that planet we'll be evaporated into steam and you won't have the liquid water that you need for life on the other hand if a earth-sized planet is too far from its host star it will receive too little star light and be too cold the water if any would be frozen into ice and snow again not suitable for life as we know it its planets in between in the so-called habitable zone that will have just the right temperature so that water will be in the liquid form so certainly at least biology as we know it and obviously all of you could raise your hand at this stage and say yeah but what about biology that we don't know about nonetheless with regard to biology we do have some appreciation of its this habitable zone where water would be liquid that represents a clear foremost property of an earth-sized planet that is required as far as we know for life as we know it but what other properties might be necessary for a habitable world chemistry geology atmospheres well there's no better way to understand the properties needed for habitability than to go to one of the least hospitable places on the surface of the earth namely our beloved National Park Yellowstone and indeed I'm going there next week to go again to look at the hot springs which I'll show you in a second because as you all know in Yellowstone the water comes out of the ground steaming boiling hot nearly so in the winter there's five meters of snow the organisms the life forms at Yellowstone must endure both boiling temperatures and freezing temperatures just within six months and then just to give life a kick in the pants the water is highly acidic how could life ever thrive in such a hideous thermally and acidic and alkaline bizarre environment well it turns out it does thrive as probably most of you know when you go to the hot springs like here you see different colors coming off of the hot springs you see it with your own eyes and each color represents a different species bacteria with its own pigment that thrives in the temperature and acidity domain of that flow line so each type of bacteria is proliferating in the temperature and acidity of its choosing and then it thrives and reproduces if you want to even add to the misery of these bacteria you simply bring pH paper that you steal from your high school chemistry teachers lab room and you dunk that pH paper in the water you can see the colors there in the background still that's the bacteria in during the the nearly boiling temperatures and you read off the pH it turns out to be - in about half of the hot springs in Yellowstone you can just verify what the biologists have been studying and saying for a couple of decades now and there you see whoops there you see in the background this lovely beautiful filamentous bacteria like angel hair pasta and yet it's thriving despite nearly boiling temperatures and an incredibly high acidity near battery acid like acidity one of my favorite hot springs is the grand prismatic spring you hike up go off the trail don't tell the park ranger go off the trail go up in the mountain here you see volcanic rocks in the foreground and there's this lovely hot spring with the steam coming off and the different colors showing you that the bacteria are as happy as can be despite the crazy and bizarre conditions there and in fact my favorite hot spring which I can't wait to go to in a couple of weeks when I get there is churning cauldron you can see how it got its name just look at the water there churning boiling gurgling I didn't dare place the pH paper held between my fingers in churning cauldron so I tied the pH paper to a black metal clip that you can see and then I tied the black metal clip to a string and I tossed that thing into churning cauldron to see you know what the pH would come out to be I didn't know and and I pulled this thing out and there's the pH paper came out - battery acid again and indeed look at what was a black clip and then as if to laugh in our human faces look at the string the critters just clung to the string that we're happy swimming living their lives out in that nearly boiling acidic water so you can be a little amateur biologist when you go to Yellowstone with nothing more than pH paper and a thermometer it's really terrific and you can just tell how happy the bacteria are living their lives out there these these microscopic critters with lovely names that tell you how much they enjoy the heat are sending us an astro biological message they don't come from 25 light years away they're right here in our backyard and they're telling us that if there are other Earth's out there with crazy temperatures wild acidities less sunlight more sunlight maybe not very much oxygen whatever there will be life-forms that nonetheless endure and actually thrive and so these these unintelligent life-forms are sending us one of the most intelligent messages we could have ever gotten essentially from outer space but doing so from right here in the extreme environments on the earth and so the message is clear right on almost any earth-like planet where the temperature allows water to be in liquid form all of the ingredients for life are common there the recipe for life is clear you need a petri dish with in which to mix up the chemicals the organic molecules and indeed the ingredients for life the the carbon-based molecules the methane ethane another carbon-based molecules organic molecules very common in the universe and you need to mix them up with some sort of a solvent some cocktail mixer if you will like liquid water maybe some other liquid can do the job as well and then you need to mix in a little energy so the reactions can take place and so very simply the the the kitchen elements are there for you to cook up life on any such planet never mind the acidity and the temperature in detail and of course there are many energy sources so the only worry about that there's radioactive energy tidal energy geothermal energy never mind stellar solar like energy and so the molecular biologists are unanimous if you take a poll of molecular biologists throughout the world and ask do you think there's microbial life out there in space they'll kind of wince at such an obvious question because they are very sure the answer is sure you're going to get organic molecules forming amino acids we already see them in the comets and then the interstellar clouds you're going to eventually get proteins and eventually get replicating molecules that replicate and compete for the available resources in their environment so there's no question I would say at least from our intellectual theoretical standpoint no question that simple single-celled life ought to be common as far as we know but then that brings me to the last part of the talk about which I know nothing at all and that has to do with intelligent life and it is really it's it's embarrassing that we to this day in 2011 don't know much about the possibilities of intelligent life technological life elsewhere in the universe I'll tell you a few thoughts that I have and they're sort of my own personal view not necessarily shared by everybody but but I'll try to mix in some alternate points of view when you look at our Milky Way galaxy and you ask is it teeming with life as gene Roddenberry depicted in Star Trek are the Romulans and the aliens of Romulans and then the Klingons and them the Cardassians fighting each other and engaged in commerce and you know cordoning off quadrants of the galaxy and so on are there other salesmen out there who are really ready to bilk you out of your your spaceship and so on well you know you can do some simple calculations to ask if Roddenberry was right there's 30 billion at least 30 billion planetary systems in the Milky Way galaxy just based on the Kepler information I've shown you to under billion stars so there's 30 billion planetary systems at least probably more and then you might ask well what fraction of those planetary systems harbours intelligent and let's be more specific technological life what fraction of those planetary systems spawns primitive life which then evolves into intelligent life nobody knows the answer to this question I think the most pessimistic answer I ever heard was from Frank Drake who said the worst it could be is one in a million maybe intelligent life is one in a million so let's take Frank's a pessimistic view if you take one in a million and you multiply by 30 billion you can immediately see there's thousands tens of thousands of advanced technological civilizations and I do mean advanced because of course many of them got their intelligence a million years ago or ten million years ago or even maybe a hundred million years ago they would be tens of millions of years advanced technologically compared to us humans that just got radio technology a century ago so it's pretty impressive to think that well maybe Roddenberry had a point that's a lot of civilizations maybe this idea that we saw on TV was basically correct but is that true you know you you all look up into the night sky and we don't see alien spacecraft routinely yes there are claims of UFOs they're always made by farmers in Iowa I don't know why it is that that it's the corn farmers in Iowa that see all the UFOs none of the rest of us get to see them but other than the Iowan farmers you know we actually don't see this we don't see it with our telescopes that the galaxy isn't so teeming with life that the the alien spacecraft reveal themselves and so that begs the question well what would we have seen if the galaxy were teeming with life and you start realizing that actually we do have some non detection zatt our fingertips for these advanced technological species for one thing the moon does not have an obelisk as we all saw in 2001 there's no crash debris there maybe they wouldn't have come to the moon but maybe they would have the moon represents a non detection as no telescopes left there by the Cardassians of 500 million years ago to watch the evolution of us humans similarly the planet Mars now has been photographed very nicely indeed we have two spacecraft orbiting Mars right now and we have metre scale photographs of Mars in there no cities there's there's no telescopes down there no advanced civilisation came and left a telescope to monitor us on the earth or even monitor Mars so there's another non detection you might say and one of the greatest non detection zuv advanced technological life is right here on the earth certainly the earth has been a shangri-la for advanced life forms for several billion years there have been beachfront property and tropical rainforests on the earth far before the the Homo sapiens and the australopithecine arrived here and yet no advanced life-form came and you know came from a Tau Ceti and set up camp here on the earth so the earth is sort of a giant non detection of advanced technological life you could argue about these things of course moreover every night professional astronomers all over the world use their professional telescopes they're aimed at different stars and galaxies if any UFO were to appear in their field of view I would see it tonight when I'm looking through the Keck telescope I'll be watching the field of view never in my experience nor any other professional astronomers experience have we seen a spacecraft or some alien peering back through the telescope at us it just doesn't happen again that's where the the Iowa farmers seem to have the best telescopes in the world the night sky doesn't show the gamma rays from the matter/antimatter engines of the enterprise and and other such craft so at least there's no indication of that kind of propulsion system and moreover when we look up into the night sky here around the earth we don't see even simple small robotic spacecraft sent here from the advanced civilizations that exist maybe within tens light-years that sent a very simple camera to kind of spy on the earth why don't we see their their their spacecraft their satellites kind of watching over us we just don't see them and then it's somewhat embarrassing to say here we are in the SETI Institute clearly one of the greatest scientific institutions on the planet Earth and despite our best efforts we have not succeeded in something like over 40 years to pick up the radio waves from the advanced civilizations it's extremely frustrating and and all of these factors start sending a message that maybe the galaxy's not teaming with advanced technological life it's out there for sure we can't we can't argue against it there must be some smart critters out there somewhere but maybe their density is lower than we thought we've made some over estimate the Gene Roddenberry's of our mind have somehow overestimated how come an advanced life is and maybe we can figure out how we did that over estimate because the aliens would have wandered here by chance if they were out there even if they didn't know where to go so how might it be that we've kind of you know been overly enthusiastic about the density that come how common intelligent life is well I'll just offer a few ideas and these are really just my own personal ideas about it it's possible that our planet Earth is a little more special may be greatly more special than we thought and this is arguable one of the attributes for example indeed is water it's not just that the earth has liquid water yeah that's a prerequisite for life as we know it but the earth has just the right amount of water 0.06 percent by weight is the is the earth in the form of water plus or minus a little and if you can imagine if the earth somehow had delivered to it by comets and asteroids less water let's say a factor of two so it was 0.03 percent water well then much of that water would have been soaked into the sponge the mantle of our planet Earth maybe even into the core and this surface would have far less water than it does maybe drying it up completely and we would be in a desert world you might say desert roll out come on what are the chances of a terrestrial planet being a desert world well Venus and Mars are two neighbors on either side have no water on the surface at all so we have two desert worlds right in our backyard and moreover you could ask well what if the earth had somehow acquired a little bit more water not 0.6% but maybe twice that much well then there the oceans would be so deep that the continents would be nearly covered yeah maybe Mount Everest would poke out above the water world and we'd be living on a planet that was like a you know a bad Kevin Costner film so you know it's possible that our planet Earth is a sort of one in a thousand throw of the dice not one in a billion maybe but one in a thousand we have just the sliver of veneer of water so that the plate tectonics allows the continents to poke out above the oceans keeps without that you might argue that technological life would be challenged how could we build you know electronics never mind pianos and rocket ships if we had a world covered by water that the circuits would short out sort of literally and metaphorically another interesting aspect of the paucity of intelligent life in the galaxy comes in Darwinian evolution if you ask the world's greatest evolutionary biologists our big brains a natural byproduct of Darwinian evolution are we humans at the pinnacle of the Darwinian evolutionary tree like we like to think of ourselves there are fairly unanimous and saying no that we humans have attributes that have somehow allowed us to compete in our environment but that intelligence is just one of tens of thousands of properties that an animal can use to compete hard shells long necks fast running speed long teeth many many other attributes allow species to compete not just big brains and there's no better example of this how shall I put it humility of brain size then looking at the paleontological record of the dinosaurs over 200 million years of dinosaur evolution yielded brains the size of chicken brains it's incredible to hunt we humans have been you know we've been since the Homo erectus it's only a hundred thousand years or so the dinosaurs had 200 million years by which Darwinian evolution could have yielded a slightly smarter dinosaur from one generation to the next even smarter by a smidgen would have allowed the dinosaurs to out-compete each other by virtue of their intelligence and yet at the end of dinosaur evolution 65 million years ago the smartest dinosaurs had the had brains that were literally the biggest was the size of that of an ostrich and in fact that that's been measured you can take the cranial sizes of dinosaurs and the biggest the smartest of the dinosaurs was that Troodon and there's a a model of the Troodons brain and there's an ostrich brain an albatraoz brain and indeed we know today that dinosaurs are birds or maybe I should say birds are dinosaurs so it's not surprising that dinosaurs really more or less had the brains of birds and and you can even graph where the dinosaurs sit relative to the mammals and body weight and cranial size relative to body mass and so on so this is a poignant moment where you realize that intelligence was not an obvious driver for the properties of this species that the reptiles for 200 million years and maybe that's true in general maybe intelligence is just something that's a quirk we're a twig on the evolutionary tree we're not at the pinnacle and then of course we all know that even some of the animals that we know and love today like bugs and dogs and cats they certainly aren't getting any with time they're just as smart as they need to be my friend Laurie Marino likes to say that even the Dolphins which are smart but they're just as smart as they need to be so there's not a lot of evolutionary pressure and I think what's exciting to are the the the species on the earth that have no brains at all and they have done perfectly well thank you very much the jellyfish are not just boneless they're brainless and they have survived for a billion years never once developing a cerebral cortex so there's a clear evidence that species can thrive and even evolve but brains and technology may not be a necessary and product of evolution and then one of the ideas that Carl Sagan used to talk about and I think it's lovely and and profound is that maybe part of the reason there is a paucity of intelligent species out there is that once they have the technological abilities to build rocket ships they also endanger their environments they can build weapons biological chemical nuclear and so perhaps their lifetimes our finite maybe intelligent technological species lasts typically ten thousand years or so which would be great if we can live that long and then they flicker in and out like lights on a Christmas tree throughout the galaxy so that's a I think our cautionary tale about the challenge we humans face as an intelligent species maybe we should be much more careful about how we treat ourselves and then I think I'll just finish tonight by saying that these topics of the so-called paucity of intelligent life it's certainly out there but how common is intelligent life are they are there a hundred intelligent civilizations in our Milky Way are there a thousand of them are there maybe only two or three maybe even only one we can only answer that question by doing the experiment we absolutely must build as one of our greatest causes as a species ourselves we must pursue the search for other intelligent critters out there like ourselves and a lovely new radio telescope is being built near Mount lassen the Paul Allen radio telescope array you can see some depictions of it here and of course we now know where to point the Allen telescope array because we have some of these earth sized planets found by Kepler so we actually know where the earths may be and we can then search for radio and television transmissions from those intelligent species if any on those planets but there's a there's a sobering news flash to provide all of you with some of you know this that the Allen radio telescope array is currently struggling to find funding it's just very hard to find enough money to build and operate these lovely new high-tech radio telescope arrays with which we could pick up the the technological signals of other civilizations so we need help there's just no doubt about that and hopefully somebody maybe in this audience or somebody that's that will listen to this talk will realize that a great quest of humanity is is struggling for lack of funds and there are other ways to do SETI searching for extraterrestrial intelligence one is using modest telescopes but putting special light detectors that can detect lasers perhaps the alien civilizations that transmit communication signals to their brethren on another planet or on another spacecraft by laser light to maintain some degree of privacy and intensity of their communications so as there are people here's Shelly right professor Shelly right now a professor at University of Toronto using a telescope here in Northern California at Lick Observatory where she's attempting to pick up laser signals from other intelligent species he's also using a Berkeley a telescope over there here's one of her designs she's just finished a proposal she too needs funding to carry out her SETI search so this is part of a proposal to NASA but you know it's hard to get money these days out of the federal agent and then I myself and trying to do a little of this we're using the Keck telescope in Hawaii to hunt for laser lines and this is a somewhat complicated graph but that little dot there is what we would see if an alien civilization happened to be shining its laser by luck somewhere toward the earth we would pick up a little dot in the confined in wavelengths ie colors and confined in angle in the sky because the laser would be an unresolved dot and so we're beginning to look for these laser dots in our data it's a long shot for sure but if you don't look you'll never find one that's just the way it is so I'll finish by saying that where we are in a special moment I think this is an amazing moment in human history we're finding the first earth-sized planets we have answered essentially Aristotle's question we do know that there are other Earth's out there the earth is not unique nor special it's possible that intelligent life is a little more rare than the Star Trek and Star Wars science fiction novelists have told us primitive life is probably common as far as we can guess from Yellowstone and elementary biology technological life may be more rare than we had thought but if so it's even more precious and so it gives us I think an impetus to think about our own civilization how we can survive long enough indeed to find those other precious civilizations that are out there and the bottom line is only if we devise SETI searches and look will we be able to answer this question so I'll stop there Jeff I'll just start with the quest questions can you tell us a little bit about what you'll be doing to follow up the Kepler detection Xan what what is it that you'll be doing a kick to actually to tonight well tonight I'm going to drive away from here and at Berkeley we have a remote observing facility that allows us to use the Keck telescopes that are on top of the hopefully dormant volcano Mauna Kea on the Big Island of Hawaii and what we're doing there is trying to verify the planets that Kepler finds because as I mentioned there's a small probability that we're being fooled some of them are certainly not planets and we know how to sort out which that the wheat from the chaff and then also by watching for that wobble of the star we can determine the mass of the planet and we'd like to get the mass again because the mass plus the size of the planet gives us the density and we really want to know how common are rocky planets like the earth because it's that hard surface on which the water can puddle into lakes and oceans serving again as that as the cocktail mixer for life so it's it's getting the mass with the Keck telescope that gives us the solid constitution of the planets and once you've done that does it become a planet rather than a planet Kennedy yeah once it does that we go to the Kepler team and we have a vote actually to be honest with you in fact we we met in this very room a week ago and we had some votes and and people say yay or nay I think it's a planet and hopefully the planet passes unanimously and then it it gets deemed a planet yeah certain moon systems in this solar system are double moons have you observed any double planets no it's a very good question I think by double planet you mean a star with two planets that are orbiting each other and I could tell you that we probably would detect them with Kepler because we would see one planet dim the star and then the other planet would dim the star and then when the whole thing went around they'd be in a different configuration but we would still see one planet and then the other one didn't the start yeah exactly we'd see a step function in the brightness and so far we haven't seen that we look by eye at the light curves as we call them brightness as a function of time and so far we haven't seen nor moons for that matter and what you're talking about is essentially the same thing as hunting for moons where we would see maybe one dimming and then another dimming due to the moon so far not and maybe you know we're going to keep looking but we have a few T's Kepler team members who are specifically hunting for these four possible moons oh yeah you made two points or like your comment on one is that you've generalized that the that the world that there are preponderance of smaller planets rather than larger planets but would you also say that that's only out to two-thirds a you were there abouts that you have checked so far that actually the full generalization will take you know the seven years that we anticipate running Kepler further and then the second in terms of big takeaways from Kepler for me and and I'd like your comment on it is that is that you've now detected about 1,250 planets roughly 1% of the stars that you're looking at have on an average of one planet part per hundred right however since only 1% of the systems would be edge on and deductibles consequently there is out to 2/3 au an average of one planet per star systems which means that in the Milky Way there must be you know 400 billion plus planets if you extrapolate yeah so let me I'll answer both of those first question just to recap his question the Kepler mission has now been going for two years but we've actually only processed the data because it's very difficult for the first roughly half a year and so we're only sensitive to planets that would have orbited their star three times to give us a dimming a second dimming then a conformational third dimming if the orbital period were less then about two months or so and so the data I showed the graphs I showed only pertain as you mentioned to the close in planets and as the Kepler mission acquires more and more data over the years hopefully another three or four years with more funding we will be indeed sensitive to planets that take a full year to go around their star like the earth does around the Sun and so we're going to learn the statistics of the occurrence of planets the size distribution of planets for those planets that orbit farther from their star not just a close close in one so you're seeing the early that the early days and your your other question was was a brilliant one and I'll explain it again he noted that only about 1% of the Kepler stars show planets but that shouldn't be the take away number because Kepler can only detect planets if the orbital plane is viewed edge on to our line of sight out to the earth any planet that resides in a tilted plane will not cross in front of the star and therefore will not dim the star so we miss all of those the good news is this is a simple high school geometry problem you can ask for all of the planets you did detect how many would have been in the other orbits tilted randomly that you would not have detected and therefore you can account for them and when you do that you find that something like 30% of all the stars have a planet within an Earth's Sun distance you you used the term au so within an Earth's Sun distance it looks like something like 30 / yes exactly that's right we're only so far I've reported only and the Kepler team has only written papers on planets very close in that's right and so the best is yet to come yeah oh oh sorry go ahead yeah yeah a couple questions about the likelihood of primitive life one regarding the harsh environment the fact that life has seen harsh environments on earth but that could be because I mean it may be that life evolves or develops in the most favorable environment and then gradually adapts to these are short vironment so it may that may not tell you be as quite as optimistic in the other there was just an article in The New York Times about a fellow who developed a replicating organism and right I thought one of his comments was was particularly pro but he said it drives him nuts when he hears exobiologist or whatever on immers talk about the frequency because I have no idea I mean how can they say how can they come up with any kind of figure right like you respond to this no well of course you know I would 100% agree that we we simply don't know even about how common primitive life is because it is still the case we don't really understand the origin of life the early microbiological steps at the molecular level that led to the primitive life on the earth and until we understand that well it still could turn out that even simple life is is more rare than we had thought and your first point was yeah well you know it's interesting Yellowstone is a peculiar place and in profound ways we think of it as a harsh environment but in fact the leading hypothesis for the origin the site at which life formed on the earth I would say the leading hypothesis is that it formed in hot volcanic vents at the depths of the ocean in the bottom of the ocean why well because at the bottom of the ocean primitive life-forms would have been protected from the UV light coming down from the Sun in the days prior to having any ozone and there wouldn't have been any ozone because there was no plant life to photosynthesize oxygen and protect the early life-forms so the best way to form life in a way that's protected is to do it underneath at the bottom of the ocean so maybe the volcanic conditions we see on yellow stay at Yellowstone are in fact representative of what were the the suitable the the lovely tranquil locations where life got kick-started early on rather than the harsh environment that we think of it today actually now I have two questions observation first about since we were talking about the geometry before because of the geometry of transits the likelihood of discovering planets further and further away from the star become less and less that's exactly correct yeah and I can give you the number for those of you who are mathematical geeks the probability that a planet orbiting its star will just happen to cross in front of the star as you'd from us at the Kepler telescope is equal to are you ready the radius of the star divided by the orbital distance between the planet and the star so you got a star in the orbital distance and you can see that a star could be quite a bit smaller than the orbital distance of the planet to the star so that ratio that that fraction is about 1% for the earth a planet in an earth-like orbit planets in earth-like orbits only 1% of them will be so fortunate as to cross in front of the star and allow Kepler to detect them thank you and the observation I wanted to make was that you observe that there are a predominance of smaller planets out there isn't this sort of confirmatory of an accretion model yeah and I'll just fill the rest of you in what the leading model for the formation of planets is that dust particles floating around in a young protoplanetary disk those dust particles collide stick and grow into ever larger blobs of dust other dust particles coming in you end up with a fractal dust bunny and eventually these things get larger and larger and they form the size of sort of pebbles and asteroids comets and eventually planets and yeah the fact that you see more of the smaller ones seems consistent with and there are other reasons to think it's consistent with this model of the solid dust particles being the the seeds of planets as the system ages then I would expect to see a peak forming as planets will start to sweep out their zones yeah and that's how the theory goes that planets should carve out gaps in their protoplanetary discs gravitationally sucking up all the material near them and then you get their phonograph grooves around the protoplanetary discs in that one slide that you show the planets going around the various Suns the slides show them going all counterclockwise is that in fact the case yeah that's because God lives above the planetary system if God lived below we'd have them going the other way so um please go back to one of the light curves that you you know he showed it in the middle of the talk on what come you know what I noticed is even when there wasn't the transit there was quite a bit of scatter in you're a mean person you're calling the Kepler data noisy I don't know how to go back all that way but the the y-axis that noise is only one part in 10,000 so the noise fluctuations I don't know I guess I should just break out of PowerPoint here those noise fluctuations are just a hundredth of one percent I'll see if I can find the graph that you're that you're thinking of here but now that you've with me I have to go out and find this thing I was well-meaning yeah you know I mean this is 0.999 of the brightness of the star and here's what you're calling noise right so what I was getting toward is what's the smallest planet you know the coupler can ya detect you know before you get lost in the middle yeah yeah yeah and how is that trying no that's a very important question and the the quick version is that we think Kepler can find planets about half the size of the earth and that will require that a number of transits maybe a dozen or 20 transits so you build up over and over again the dimming and so that dimming that are even let's say a tenth as deep as this you would still be able to discern it in the data and you can sort of see by eye if this planet is only 40 percent bigger than the earth how small a planet could you in fact detect and the obvious answer is considerably smaller than this one right and then another question the planet was orbiting once a day yeah you said you know it it has one side that always faces the Sun and the other side the Solway that's right is there a certain radius with within which we expect that to be the model yeah that's right um planets that orbit their star and take about five days or less the theory suggests and even observations suggest that there will be tides raised on the planet a bulge on the planet toward the star inducing a torque that will cause that planet to keep one face toward the star at all times planets more distant than than a few ten days or so those torques are much smaller and so the the title couple the title coupling is much weaker hi I was very interested in the transit timing variations yeah and I was wondering you know you talked about two scenarios that we wouldn't detect farther out planets one is if the Sun has tilted just a little bit if the solar disk right tilted we won't see them also obviously we've only been looking for like a couple of years and anything with a period of say four or five or six or you know longer than four years we may never see that planet but could those planets be inferred by their variations on the ones that we do see yeah it's this beautiful question and I'll just restate the question because you've almost answered it by virtue of the eloquence of the question itself that there are of course going to be stars for which we see one planet that does transit and we see the time of transit lead or lag what we would have predicted because of some other unseen planet that's gravitationally yanking on the planet we do detect and so we will be able to not only infer the existence of other planets but measure their masses incredibly despite there being no real data on that other planet at all it's out of the plane it's tilted out of the plane but it will be yanking on this this seeing planet and by the way this is not really news it's about two hundred years old because the discovery of the planet Neptune in our solar system many of you know was discovered by watching the timing of the planet Uranus and noticing that it was sort of perturbed in its orbit and that allowed people to infer the existence of and even the location of Neptune before it was ever detected so we're now doing that with planets around other stars the people that plan the Kepler mission chose a direction to look that's a it's a fairly sizable chunk of sky but it's only one chunk of sky can you comment on that choice and how likely it would be or how much better that spot is then say a different random spot in the sky yeah we thought very hard about what patch of the sky to survey it goes back 10 years we started thinking about this and here's the advantage of the field near the Cygnus constellation as the earth goes around the Sun and the Kepler spacecraft is trailing behind the earth there's a spot perpendicular to the orbital plane where the Kepler else coke can continuously look if instead the Kepler field of view were somewhere in the plane of the orbit of the earth then the Sun would get in the way half about half the year so we purposely chose a domain of the night sky near over near perpendicular but there was another key consideration and that is we wanted a hundred and fifty thousand stars and it's the plane of the Milky Way galaxy the wash of stars that goes overhead where the density of stars is so great that the Kepler spacecraft would be able to capture 150 thousand stars so there is a spot nearly perpendicular to the orbital plane where the Milky Way goes overhead where in fact we chose to observe in fact we're not right in the plane if you saw the picture because in fact in the plane of the galaxy there's too many stars there actually too crammed together so we chose alas spot a little bit away from the Milky Way and then the last answer to your question is well ok that's fine up there what about the equal spot down below and we chose the one above because here in the United States we have telescopes in the northern hemisphere and and and that's to our advantage so the Keck telescope in Hawaii being you know in northern latitudes allows the Keck telescope to survey the Cygnus constellation like nine months out of the year so we at the very last moment we made a small decision that favored the ground-based telescope resources that we had to follow up the Kepler discoveries with these light curves I think it's getting whatever it's whatever the planet is is covering the Sun it gets dark on the other side is there a chance it would actually show a blip of light because it's reflecting and if so could you look at like the spectral lines and tell a little more about the planet you should be giving this talk you let me repeat his question because again he almost gave the Hetzer by virtue of the question beautiful question it's true that when a planet goes in front of a star it blocks a little of the star light and the star dims and that's how we detect them but when the planet goes around the backside of a star you're seeing a sort of full moon which is what you were essentially saying you not only see reflected light off the planet now it's fully illuminated you see the hemisphere that's illuminated but also that's the hemisphere that's warmed up by the star and so we get what's called thermal radiation that is to say infrared light from the warmed up hemisphere so if you use an optical visible telescope you see a brightening at quote full moon it's really full planet and you if you use an infrared telescope like the spitzer space porn telescope you see a little enhancement of the infrared light as the the warmed up hemisphere comes into view and as you said you're quite right we can even then take a spectrum spread the light out from the planet into all of its wavelengths or colors to look for spectral fingerprints of the chemical elements like water carbon dioxide carbon monoxide methane and so on the common molecules of most planets and that is in fact observed not for the Kepler stars because they're too faint but other planets that go around stars for which we've already detected them we make such measurements you mentioned one of your other answers that you've only processed data for planets with a period of two months or less and I sort of occurs to me that that can't be anywhere close to the habitable zone right for any of these stars that's basically right yeah what point do you think that how will store zone is going to start in terms of periodicity well we're getting there you know just we can do the math in our heads the the earth takes one year to go around the Sun so and the earth we normally think of as being near the middle of the habitable zone for a solar type G star and so we like on the Kepler team to wait for three transits you see one dimming that's great you see second dimming is that really due to a planet or could have just been to random dimming x' but if you see the third one and it's timed synced up with the first two then you probably really do have a planet but that means you have to wait for three orbits which means you have to wait for three years and the Kepler telescope will only been up for two years and we're a little behind processing the data because it's very complicated so it'll be another year or two frankly before we're sensitive with the Kepler data two planets indeed including earth sized planets in the habitable zones of sun-like stars and one last footnote of course is that there are stars that are less luminous than our own Sun those stars are have such low luminosities that the habitable zone is quite a bit closer in to warm up your face around the campfire when it's dwindling in its light you better bring your face a little closer to the campfire and so those the habitable zone around a dimmer star is closer in and we are already sensitive to the habitable of the planets in the habitable zone for those low luminosity stars but they're very few of them so we don't have enough of those stars to get a good statistical sample yet so I lucked out because you have that chart that I asked about a bunch of transit exactly is it correct that any one transit would just have a sudden drop constant low level and then sudden increase and so what we're seeing is transits through different different curves through the stars ah no yeah I see what you're thinking it's a good idea but what is what we suspect is most likely the case is that if you have the disc of a star the planet as you suggested might not cross right across the equator but instead across at what we call a chord you know slicing through the star near the bottom or some way in between the middle and the bottom but it would do so the same geometry the same distance time and time again so if the orbital plane for example is tilted just a little bit the planet will always cross a little high or a little low over and over and over again so this curve is what you see for each individual transit and we're just building it up with many many more transits but each one has an as we call an ingress and then a flat bottom and then the egress and they'll all have exactly that shape yeah there's a brightness variation across the disk that's what gives this little bowl shaped here and the ingress is due to the fact that the the planet nudges its nose if you will into the star and then it takes about a half an hour for the planet to completely get engulfed within the star so that's the the duration of the time it takes for the planet to fully go into the disk of the star and then here's the time it takes for the planet to fully emerge from the star ingress and egress we call them I love what would you like to see in a next-generation instrument oh boy am I glad you asked that so there's two things we need and this is just glorious because we know the answer the first thing that we need is a space born telescope much bigger than Hubble with a so called coronagraph that blocks the Starlight and allows us to actually see the planets notice I didn't show any actual pictures not even a dot of light we don't currently have a space born telescope something NASA would build that can get us a picture of the earth-like planets around these stars especially nearby stars and allow us to take a spectrum of those planets to give us a chemical assessment a chemical measure of how much of the various molecules in particular life bearing or life related molecules bio signatures as they're sometimes called so the first wish list you know for for Santa would be a ten billion dollar space boring telescope but that's what it would be and it would be built in conjunction with Issa in Europe with Japan China and India and Canada and other countries combining our resources to build this fantastic basically epochal telescope that could take the first pictures of and spectra of earth-like planets around other stars that's number one on my Christmas list since you asked number two is a SETI telescope we need a telescope like the Allen telescope array frankly it's only in the realm of a hundred million dollars or so that would be a spectacular SETI hunting machine that could pick up faint radio and television transmissions from stars you know halfway across the Milky Way galaxy those would be wonderful instruments that I think you know humanity could be very proud of okay if anybody has any final questions I encourage you to come up here and speak to Jeff after each talk Jeff we have a mug with a picture of potentially one of those instruments that you wanted for Santa so he's okay but hope there it is deliver the real thing sometime in the near future thanks ray

Channel: SETI Institute

Views: 36,937

Keywords: Geoff Marcy, uc berkeley, exoplanets, seti institute, carl sagan, astronomy

Id: jLNO5nXZoUI

Length: 93min 37sec (5617 seconds)

Published: Sun Sep 18 2011

Reddit Comments

[u/[deleted]]

As Mr.Spock would say "FASCINATING". Geoff has the chance to rival Carl's place in history . Educating regular man to the discoveries in Astronomy. I watched it twice....... no lie!

[u/rounder421]

He didn't really take into consideration a moon(s) in his speculation on the commonality of intelligent life. This is just speculation on my part, but wouldn't having a moon controlling the tides and orbital speeds on a planet have a large impact on the development of life? Rocky planets with water with a moon would be pretty rare in systems wouldn't they?