How Kepler Found One Planet Every Day: Jason Steffen [Ep. 470]

Get ready to embark on a cosmic journey with Jason Steffen, author of Hidden in the Heavens and one of the brilliant minds behind the groundbreaking Kepler Mission. This live episode of The INTO THE IMPOSSIBLE Podcast promises to be an unmissable masterclass in exoplanet science, filled with awe-inspiring discoveries, behind-the-scenes stories, and lessons that redefine our place in the cosmos. What You’ll Discover: 🚀 The Kepler Mission’s Epic Journey: Learn how a team of visionaries overcame two decades of challenges to launch a space telescope that revolutionized planetary science. 🌍 Earth’s Place in the Universe: What have 5,000+ exoplanets taught us about the possibility of finding Earth-like worlds—and the uniqueness of our own planet? 💡 Breakthroughs That Changed Science Forever: From “hot Jupiters” to the unexpected diversity of planetary systems, explore how Kepler rewrote the rulebook on planetary formation. 👩‍🔬 Inspiration for Aspiring Scientists: Hear Jason’s advice for navigating uncertainty, thriving in collaborative missions, and turning curiosity into impactful discoveries. 🔭 The Future of Exoplanet Research: With the James Webb Space Telescope building on Kepler’s legacy, what’s next in the search for life beyond Earth? Why You Can’t Miss This: This isn’t just a podcast—it’s an educational experience for anyone fascinated by the cosmos, science, or humanity’s eternal quest to answer the biggest questions. Whether you’re a seasoned scientist, a student of the stars, or simply curious about our place in the universe, this episode will leave you inspired and enlightened. Learn more about your ad choices. Visit megaphone.fm/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

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• 0:31Speaker 01

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• 1:03Brian Keating?

  All right. Welcome, everybody, to what is going to be an amazing journey through the universe of exoplanets. Something we cover a lot on this channel, and today is no difference. We have an incredible guest joining us today, all the way from Las Vegas, Nevada, or as I call it, Lost Wages, Nevada. And I hope it'll be as exciting for you as it is for me. Reading his book. He's got a wonderful new book out called Hidden in the Heavens. And we're going to play our favorite game of judging the book by its cover in just a minute. And let me just first introduce Jason Stubb. And Jason, how are you today?

• 1:45Speaker 03

  Doing well. Thanks for having me.

• 1:47Brian Keating?

  Congratulations on this great new book. It's a, it's quite a, quite a big deal to write a book like this and to do it in such a way that's understandable even to a simple cosmologist like me. We've had on a lot of interesting guests lately, talking about exoplanets and life. And I guess while people are trickling into the live stream, I wanted to ask a question. What would you say if we found out there was no life on any other of these exoplanets? Earth's the only thing we got. Would you still say searching for exoplanets is a worthy goal of a scientist?

• 2:24Speaker 03

  Yeah, I can. So one of the things that I, it's a good thing that there aren't, that people are still trickling in before I, this gets too broadly sent out is that I don't, I don't really care about life on other planets all that much. So one of the reasons I think that studying exoplanets is useful in its own right is that it tells us all of the paths that our solar system did not take. We learn about how planets form. It allows us to have a more general theory of planet formation. That the solar system alone can't, can't provide. So the solar system doesn't provide enough breadth in the zoology

• 3:10Speaker 03

  to really have a good, robust planet formation theory. We can have solar system formation theory, but planetary systems look way different than we would have anticipated from, from the solar system. And so having, you know, observing these other planets gives us a better understanding of, you know, how our origins came about and what's different about our solar system than other planetary systems.

• 3:33Brian Keating?

  And you got into this rather circuitously, did you not, from originally potentially studying, you know, gravitational fields and other, in other spaces, perhaps at University of Washington. This was not your intended PhD track, research track, was it?

• 3:50Speaker 03

  Right. So I was gonna be a cosmologist going in and then yeah, and I went to the University of Washington anticipating to work with Craig Hogan, who was, who was there. He became the dean and stopped taking students. So for a while I started doing torsion pendulum experiments. There are only about five torsion pendulum experiment groups in the world, and two of them are at the University of Washington. I was in the, the less famous of the two groups. But it was really an interesting exercise in like, understanding how gravity works, like weak field gravity, so like Newtonian gravity, and how to design an experiment to do,

• 4:34Speaker 03

  you know, to test, in that, in this case, it was the inverse square law. But then I went, I still had dreams of doing cosmology, and so they hired Eric Agol and his

• 4:47Speaker 03

  We were gonna do imaging the black hole at the center of the galaxy. That was the plan, and I just needed to take general relativity. And so he gave me a practice problem to chew on for about eight months. And that practice problem ended up being a dissertation that ultimately got me onto the Kepler mission.

• 5:04Brian Keating?

  And in terms of getting, you know, back and forth to the various science topics we're gonna talk about. It doesn't seem, you know, particularly natural to transition from, you know, gravity, extra dimensions and whatnot, to extra planets, extra solar planets. But I often say it's almost more important who you work with rather than what you work on. How do you react to that, both as a, you know, having been a student and now being an advisor? What would you advise an incoming new student to focus on in his or her career? The person or the subject?

• 5:39Speaker 03

  I think the subject certainly helps. But I definitely think that my advisor has a real uncanny knack for finding interesting questions to research. I can't speak for myself, hopefully I do pretty well. But my advisor really was able to find a good problem that was worth looking at. And to some extent, my personality is such that if there's somewhere where I can be useful, then I'm interested in working on that. So I'm, my interest is mainly on solving interesting questions. And that kind of overshadows a lot of the, like, personal attachment to a discipline.

• 6:23Speaker 03

  So I guess that's kind of useful advice. Like, if you can be useful, then you are more useful than if you're just working on a passion project all the time. So I will say ultimately that I did end up working with that cosmologist when I went to Fermilab. He followed me there, and not because I went there, but he followed me there because of the money. Or because he wanted to move back to Chicago where he had some roots. And so I got to work with him on some particle astrophysics-related topics.

• 6:57Brian Keating?

  Oh, that's great. So, yeah, for those of you who now are starting to get a critical mass and you'll be able to ask questions of the guests, as you often do, on the Into the Impossible podcast, where I'm always saying, Jason, you may know that I'm building the world's greatest university that's free, and you can always attend, wearing your pajamas, unlike UNLV or UCSD. And today, we're joined by a key player in NASA's Kepler Space Telescope and author of the brilliant new book, Hidden in the Heavens, which really addresses the most fundamental question, other than how did the universe begin? And that's, you know, whether or not, when we gaze out into the solar system, into, I'm sorry, into the universe, we're seeing these objects, these stars, and whether or not there's people looking back

• 7:41Brian Keating?

  or entities looking back at us, perhaps. And a lot of that will be predicated on the properties of these extrasolar planets. So today, I hope that you'll kind of get, you know, a lot of value from this conversation, including an understanding of how these planets originate and how we detect them, how Earth fits in in the cosmos, and basically, a masterclass on the Kepler mission and what it's meant for not just astronomy, but really, philosophy, maybe even, some say, theology, and our understanding, again, of how we fit in in the universe. I did a quick back-of-the-envelope calculation, you know, reading this wonderful book. Basically, Kepler detected about one planet a day over its lifetime, over 5,000

• 8:26Brian Keating?

  planets, I think, were detected, and that's really changed the way that we look at our galaxy and perhaps the wider universe. So, today, Jason, we're going to do what you're never supposed to do, which is to judge a book by its cover. So, you're not supposed to do that, you know, it's bad advice, but I think we have very little to go on unless someone already owns the book, in which case, they don't need to buy it. That's the most important thing, is buying the book, you know, and then reading it, engaging with it. But walk us through the title of the book, the subtitle as well, and the illustrious cover art as well.

• 9:02Speaker 03

  Okay, so both the title and the cover art were chosen by the press. So the working title that we had, the title that I wanted to use was Worlds Without End.

• 9:14Speaker 03

  But that was already taken by another author. And so the working title we had was Strange New Worlds. And ultimately was the press that said, what do you think about this title, Hidden in the Heavens? And I liked it. My wife liked it, my publisher liked it, so everybody liked it. But it's actually a quote from Kepler, who famously, or not so famously, said that there would be enough things hidden in the heavens that we wouldn't ever be lacking for things to study or things to look for. The actual quote's in the book, but...

• 9:48Speaker 03

  So that's where the quote comes from. I think the cover art, again, I just gave some parameters for them to work within. I didn't want something super flashy. I like kind of a nice image with some... I'm not really minimalist in my approach, but a nice image for people to get people's eye. But I think they did a great job in selecting the cover art, because it kind of shows, one, how lonely the Earth is out in space, and the Kepler missions quest to find other planets that are like the Earth. Because that was really the main design criterion was being able to detect Earth-like planets in Earth-like orbits around sun-like stars.

• 10:27Speaker 03

  And so the quest for this relatively small spacecraft to be able to find a second version of Earth, or more importantly, be able to count the number of Earths that there are in the galaxy.

• 10:41Brian Keating?

  And of course, the number of Earths in the galaxy is slightly maybe influenced by, you know, our local perspective and what we think is interesting. But nevertheless, we talk and we often overlook in science the kind of biases that we have. Not, you know, anything against any particular, you know, commemorers of our species in this case, but in the case of what scientific lacune or gaps that we're going to have in our understanding of the target that we're searching for. That's one of the things that really spoke out to me in this book, is how you went through in such great detail. What we know, we know, and what we know, we don't know, and how to kind of, you know, merge the two into one unified overall understanding.

• 11:24Brian Keating?

  And I think, you know, it'd be great, what I plan to do today... Is to go through, you know, I have my own questions, the audience is going to ask a lot of questions, I'm sure as well. But, but one of the best things about this book is the way that you're, you tell stories and, and you really communicate through the book, throughout the book, that it's a, it's a personal story, it's a, it's a human story, there's all sorts of, you know, personal interests, not only your own career, which is fascinating, but also the people that made this, this instrument possible, including on the back, you have a blurb from William Baraki, Baruki, and who's the P I of Kepler. And he has a wonderful blurb that, "Hidden in the Heavens" records the fascinating journey of a young researcher exploring the myriad of planets orbiting other stars.

• 12:06Brian Keating?

  And this is a delightful read, and it surprises and delights as well. And I just wanted to pick out a story that resonated with me in this book, of how you, and in particular William, really got through so many different setbacks. I mean, we always teach science as if it's a, you know, a smooth transition from, you know, idea to final data, to transforming the paradigms as we understand the universe. In this case, we understood now that pretty much every star you're looking at has more than one planet, perhaps, and some have very many, and they might even be Earth-like. But you tell a story about William and how he really, you know, almost lost his mind, not necessarily, but just, "I would have lost my mind." Twenty years it took him to convince NASA to fund this mission. Why was that-

• 12:50Speaker 03

  Almost lost his mind, and almost, almost lost his job as well.

• 12:52Brian Keating?

  Yeah, exactly. So talk about that, the first story that really resonated. So, on a personal level, not just scientifically, as a brilliant scientist that William certainly is, but how did he navigate these personal, political, and even technical obstacles? You, you talk about a mission that blew up, you know, or failed to launch, basically, and ended up being destroyed because of, basically, it sounded like some malfeasance on the part of the contractor that maybe was, I don't want to say, you know, anything illegal, but, but talk about that. How did he overcome these setbacks, from first proposals to convincing NASA that it was just right, not too big, not too small, and then finally overcoming the obstacles of other missions just like it, failing dramatically in explosive fashion?

• 13:33Speaker 03

  Yeah, so he started thinking about exoplanets, basically because he was an Apollo engineer. He was worked on the Apollo missions and Apollo ended in the seventies. The eighties came around and it was right around that time in the late seventies where CCD cameras started being relevant. There had been several, over a few decades, several meetings in among scientists about how to find planets that orbit other stars. There was a paper by Otto Struve in the 1950s where he said, you know, we could do it with Doppler measurements. That was his preferred method, but he also suggested that transiting planets, that we could monitor the brightness of stars.

• 14:13Speaker 03

  But at the time, the spectrographs existed that could allow for detections, or at least you could imagine improving them. But digital cameras didn't exist. That was another decade in the future. And so the digital cameras invented, it started, Baruchy started piecing together, okay, like if we were to do it this way, what would it take? And he wrote his first paper in terms of like, what would the survey entail? How many stars would we need to measure? How bright would they have to be? How many images would we have to take? How long would you have to observe? In order to measure eta Earth, which is the fraction of the number of Earth-like planets in Earth-like orbits, orbiting Sun-like stars.

• 14:52Speaker 03

  So that started in 84 and I think it was just a, he just kept seeing some promise in the method. Like if we do this, it will work. And if we make these improvements, it will work. And if we get a telescope big enough, it will work. And if we get it in the right spot, it will work. And despite a bunch of setbacks, he just persevered through, you know, rejection after rejection. I mean Kepler, it wasn't originally called Kepler, it was called Freesip, which is a terrible name, but. But eventually, you know, it was proposed, what, from at least eight times, at least six, I'm sorry, five times. From 1990 to 2000, when it was finally selected.

• 15:33Speaker 03

  But I think one of the things that he did that I think was really instrumental in getting it to work was bringing people on board. He knew that it was a mission that was too big to do one person at a time. And so he brought in expertise who could basically, he could rely on to demonstrate the capabilities of the mission, who could chime in with their understanding of different areas of astrophysics, so like stellar

• 15:59Speaker 00

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• 16:28Speaker 03

  stellar astrophysics, electronics, solar system, planet formation, as the theory existed at the time, which is way different now than it was then. So that kind of perseverance is what I think really got the mission to what it was finally launched. And there were troubles, even when they started building the spacecraft, there were still troubles that they had to contend with, with noise and instrument and making sure that it was sensitive enough to get 20 part per million photometry. And then, as you alluded to, right before launch, so everything was put together, we all had our plans to go to Florida to watch the launch and have a team

• 17:11Speaker 03

  meeting. And a couple of weeks before the, I can't remember the title of it, of the mission, like the mission that had launched, it was like the Orbiting Carbon Observatory, something like that. I think the acronym is OCO. And it's fairing, so the capsule that the spacecraft is housed within didn't separate. And so it crashed back down to the earth in dramatic fashion, just a few weeks before Kepler launched. And so Kepler launch was, okay, we need to go check all the parts, figure out what happened with this other mission, see if Kepler is going to be subject to the same, you know, kind of risk that this other one had. It ended up that the When a fairing separates, it's done with explosives. So they have some bolts that

• 17:51Speaker 03

  hold the fairing together, the capsule together, and then the bolts will explode and the capsule will open up and then expose the spacecraft. And so there was something where the pyrotechnics worked as expected, but the bolts that are supposed to burst when they're, when the charges are detonated, those were not up to the specifications. And that wasn't actually found until later that that was the real problem. But they knew it was something with the blast bolts. And so that was the part that needed to get inspected with Kepler. And fortunately, we didn't suffer the same fate. Kepler launched without any trouble.

• 18:32Brian Keating?

  And if it hadn't, right, they don't have backups.

• 18:35Speaker 03

  Yeah, they would have been bad.

• 18:36Brian Keating?

  I love it in this experimental cosmology that I work on with the Simons Observatory and other projects. You know, we can insure our project and we have insurance on the tell, you know, different parts of it. But just to get it to, you know, rebuild it would take, you know, again, it might even take longer than it took to build it the first time because a lot of times suppliers go out of business and you go down to different rabbit holes that you can't get out of. So, yeah, even having insurance of these things is not really sufficient to actually get this done. So it's kind of a miracle. And then eventually it did fail. I think, well, I mean, parts of it failed and then it was recommissioned. I think that's one of the most remarkable aspects of the Kepler story that you tell in the book. So I thought it would be fun, you know, because I'd love

• 19:18Brian Keating?

  to take the listeners and viewers on the channel along in these kind of master classes. I mean, how often do you get to talk to one of the preeminent astronomers in the world and discuss, you know, perhaps one of the greatest missions ever to be launched from Earth? And I think, you know, my, my goal, as I say, is to really get people excited and interested in space and to obviously to buy multiple copies of your book. It makes a great Black Friday gift for folks out there looking for a gift for the astronomer nerd in their family. So Jason, I thought we'd take advantage of your phenomenal lecturing skills. You're well known for giving out really popular TED Talk not too long. A while ago now, but but it's kind of pre prior to the Kepler great discoveries that

• 20:03Brian Keating?

  were made. So I wonder if you are able to now share your screen and take us through a little slideshow, a presentation. And this is really a treat for me as well. I don't get to listen to as many of these talks from eminent colleagues as I would like to. So, Jason, you've prepared a graciously prepared a nice little presentation about what went into this book and and kind of the stories behind it all. So if you wouldn't mind taking us through it and then we'll go into questions as well.

• 20:30Speaker 03

  You can see my screen?

• 20:32Brian Keating?

  Yeah.

• 20:33Speaker 03

  All right. So I guess exoplanets, we can claim some history back to Giordano Bruno, who suggested that the stars in the sky were probably had probably like the sun and had planets like the solar system. It didn't help his longevity to make such claims, but he, you know, he, he wasn't, he probably wasn't even the first person to hypothesize this, but we certainly have the record of him suggesting this would happen. If you fast forward, what, like 400 years, you get to Otto Struve, who unfortunately, it turns out, was the last descendant. So family history is something that I enjoy looking at people's

• 21:15Speaker 03

  genealogy. There had been several generations of Struve astronomers, and Otto didn't have any children. So he was the last of that line. But he proposed in 1950s that we could either do Doppler shift measurements of stars. He was studying binary star systems spectroscopically in order to kind of determine their orbits. And he's like, well, Jupiter doesn't, we don't expect Jupiter to live in a one day orbit. But if it did, we'd be able to see it with kind of the next generation of spectrographs.

• 21:48Speaker 03

  And if we don't see it that way, then we might be able to see it as it transits the host star. So that was kind of the inspiration between us for a series of discussions that took place in the 60s and 70s, and ultimately into the 80s, was what kinds of techniques can we use to find exoplanets? They weren't called exoplanets at the time, though. And even exoplanets as a spelling wasn't really finalized until the mid teens, 20 teens.

• 22:19Speaker 03

  But, so anyways, that was his proposal, and there were two different routes that people could take. And Bill Baruchy, let me skip over the Doppler shift stuff because it's not completely, not totally relevant to Kepler. But the transit would look something like this. So this is an image of a transit of Venus. If you missed it, then I hope that you eat well because we've got another 100 years or so before it transits again. So the transit of Venus is basically looking at the change in the brightness of the star when a planet passes in front of the star. So you can see Venus up here that gives basically a, what, a one part in 10,000 change in the brightness of the sun as it transits across the solar disk.

• 22:59Speaker 03

  So in order to do that, you kind of need digital cameras to be able to do something like that because the transit events are so short. So the Earth only takes a few hours. If we were observing the solar system from a distance, the Earth would only take like six to eight hours to transit across the sun. And so you have to be able to monitor the brightness of an object regularly and with sufficient precision to see something that's that rare. So you observe for 365 days, you've got six hours that your signal's going to land within. And so having both digital cameras and the computing capabilities

• 23:38Speaker 03

  were essential to having Kepler function. Because you wouldn't be able to do the Kepler mission with the computer that was on board the Apollo spacecraft. You needed something that was a bit more robust than that. It ended up being that you needed something kind of the size of a grocery store with a whole bunch of processors in it in order to get it to work out. But it's kind of, the Kepler mission is kind of the story of Bill. I mean, so I have him listed as William in the book. That was, but...

• 24:10Speaker 03

  It was everybody on the team, he was known as Bill. But this is what he looked like in the 60s when the idea of looking for planets was only a few years old. And then in the 70s, after the Apollo mission, and then he just started working. He retired shortly after the Kepler mission. The nominal Kepler mission ended. And around the time that the K2 mission was just getting underway. The equivalent of the Kepler mission would be like looking at Las Vegas from space and identifying individual bugs as they fly around the streetlights. So it's a pretty impressive feat to be able to see something like that. And to be honest, I just learned after the fact, after I'd already put these slides together,

• 24:53Speaker 03

  that Las Vegas only has about 60,000 streetlights in it. And so it'd be like having three Las Vegas's and identifying individual bugs as they fly around the streetlights.

• 25:02Brian Keating?

  I'm just glad you didn't say prostitute.

• 25:04Speaker 03

  No.

• 25:06Brian Keating?

  There might be more of those.

• 25:08Speaker 03

  Well, but so Las Vegas prostitution is actually not legal in Clark County.

• 25:12Brian Keating?

  Oh, good.

• 25:13Speaker 03

  So.

• 25:14Brian Keating?

  Cancel your trip, everybody.

• 25:15Speaker 03

  Obviously free from vices. And it's the family friendly destination that it was that it was set out to be in the 1990s.

• 25:26Speaker 03

  So I talk about cosmic strings or I talk about Las Vegas as it's kind of a cosmic string that runs through the center of an otherwise normal city. Because the suburbs are the same as basically any other suburb. But the strip itself is a place that my family and I generally avoid because it's crowded and.

• 25:48Brian Keating?

  Not very wholesome.

• 25:49Speaker 03

  Yeah. So, but this is what the Kepler camera looks like. That the camera's basically, so I have an image of what the first light looks like behind me, but the camera itself is basically the size of a cookie sheet. So it's fairly big, a large format camera in order to see really wide angles. But and it was 95 megapixels.

• 26:14Speaker 03

  Uh, the field of view was huge. It's like the size of the palm of your hand when it's extended at arm's length. Um, and I compare that to the wide field camera on Kepler or on Hubble. So, um, if I go to the, so here's the first light image from the Kepler space telescope. And next to this, uh, it's a little bit hard to see, but next to this is actually an image taken with the wide field camera on Hubble. Um, I'll, I have a circle around it. That is the wide field camera on Hubble.

• 26:45Brian Keating?

  And that's the image, uh, that's the imager that observed the Hubble Deep Field or actually that was a previous version. But I think about the same size field of view, right?

• 26:54Speaker 03

  Yeah. So it's the, it's the same size. I'm using, I think, I don't remember. I think I'm using the pillars of creation, uh, image, um, here to, to scale. I mean, it's, it's tiny.

• 27:06Brian Keating?

  Yeah.

• 27:06Speaker 03

  Um, the Kepler field of view to an astronomer is enormous. Um, and the pixels as a consequence are really fat, has gigantic pixels and the individual stars, um, will be, would be really blocky. I mean, it'd be looking, it'd be like having a telescope in, uh, Minecraft or something like that, what you would see. Um, and what it's looking for is the changes in brightness as a planet passes in front. This, uh, image here shows, um, measurements of Hat P7, which was one of the planets that was our, already discovered within the Kepler field of view. Um, there were three planets that were previously known, um, among the Kepler targets. And, um, this was in the engineering data. So they had about two and a half weeks or so of engineering data.

• 27:51Speaker 03

  And what was important was the fact that they saw the secondary eclipse. So you can see the main transit and then like on the top part of this image, you can see the main transit and then the, the flat line of the, just the star by itself. And then there's a small dip on the right-hand side. Then you blow it up and you can see that the, I mean, the dip is larger. And you can, what that dip is, is the planet passing behind the host star. So you have the planet passing in front of the star that blocks a lot of the starlight, but there's reflected light, so the planet goes through phases the same way that the moon goes through phases. And when the planet passed behind the star, then it had this secondary eclipse. And this was an important, kind of sigh of relief for the mission, because the depth

• 28:34Speaker 03

  of that secondary eclipse is roughly the depth of a transit of an Earth-like planet. So it was basically the equivalent, it was a technical demonstration that Kepler would be able to see a planet, the kinds of planets it was designed to detect. The data from Kepler are really good. I like to show this image, because the phase curve, so you have the planet going around the star, it's going to go through different phases, it'll have a crescent phase and a gibbous phase. Those phases are shown here. So I guess I should say that the phase curve for HATP7 are the data points on this plot, so the black spots.

• 29:14Speaker 03

  The phase curve from HATP7 is the red line, which doesn't go through the data. So the red line is just like you start from a crescent phase and you go through a gibbous phase and back to a crescent. What actually happens with the HATP7 system is that it exerts a tidal force on the star. So just like the earth, the moon exerts a tidal force on the earth and causes the earth to become a prolate spheroid. The HATP7 planet also causes the star to become a prolate spheroid, kind of like a rugby ball. And then, as the planet orbits the star, the rugby ball shape tracks the planet. And so, sometimes the planet, you'll see the star as though you're looking down the point, and other times you'll see it in profile.

• 29:59Speaker 03

  So those are called ellipsoidal variations. So the ellipsoidal variations is the contribution that's the blue dotted curve. And you add those two together and you get the yellow. So not only do you see the light from the phase variations of the planet, but you also see the fact that the gravitational influence of the planet is distorting the shape of the star. And the star is going through its different profiles as the planet orbits. But that's not all. If you notice that on the left hand side of this image, all the data points are above the curve. And on the right hand side of the image, most of the data points are below the curve. That is, that comes from Doppler beaming where you have the planet or the star as it's approaching you. It blue shifts the light and causes the star to appear slightly brighter.

• 30:44Speaker 03

  And when it recedes from you, it redshifts the light and causes it to appear slightly dimmer. And so you're seeing basically a relativistic effect on top of the elliptoidal variations on top of the

• 30:55Speaker 03

  of the phase curve. So the data Kepler had incredible data for studying the brightnesses of these stars. And that also means that it had really good data for studying the pulsations, for example, of stars, which we can use to measure stellar properties. So there's data on stars that are as good as data we can get for the sun, for example,

• 31:17Speaker 03

  with the Kepler mission. So it was able to find quite a few planets. This is one of the poster children of the planetary systems that Kepler found. This is Kepler 11. It has six planets all interior.

• 31:29Speaker 00

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• 31:58Speaker 03

  Through to the orbit of Venus with a combined mass that's like close to 20 Earth masses. So what this was one of the surprises, I think, that came from the Kepler mission is that when it was built, we only had the solar system to go on as a model. And so we expected that we would be lucky to find things like Venus and things like Earth, and that would be basically it. So the expectation going in, or at least during the main part of the design phase, was that we might find a few dozen Earth-like planets in Earth-like orbits or Venus-like planets in Venus-like orbits. And that was the extent of it because you wouldn't expect to form a Jupiter very close to the host star.

• 32:40Speaker 03

  It was after the Kepler science team had, at least the beginning, the initial science team had been assembled, when the first exoplanets actually started showing up. And it was after Kepler was selected that the transiting exoplanet started showing up. And it was well after Kepler was selected that the first small planets on these few week orbits were discovered. And so it was kind of a leap of faith for NASA to put this mission together based upon just predictions from the solar system. So it started finding planets right away. And what it showed us really is that a substantial fraction of planetary systems, maybe most,

• 33:24Speaker 03

  we don't actually know if it's most, but at least 30% of stars in the galaxy have planetary systems that are completely foreign to the solar system. These would include planets that are two to three times the size of the Earth on orbits that are only a couple of weeks long. So that's orbits, planets larger than the Earth that are on orbits that are much shorter than the orbit of Mercury.

• 33:47Brian Keating?

  How much is that influenced by the fact, you know, kind of the selection bias of Kepler? That it's really only able to see things, you know, a year or two in period at most, given the, you know, factors like aliasing and so forth, but but also, you know, because it's sort of optimized for the Earth-like planets, which means something like a year-long orbit, and therefore it'll get more shots at the bites at the apple for the, you know, closer in periodicity planets.

• 34:16Speaker 03

  Right, so the discoveries certainly congregate at the one month, few week to a few month orbits. They also are generally slightly larger than the Earth. But Kepler was able to find planets that are smaller than the Earth. The smallest one that it found was basically the size of the moon.

• 34:36Speaker 03

  So it was sensitive to smaller planets. The issue that you then have to deal with when you do demographics. So I guess there's a couple of stories that that come from this. One of them is when you find a planetary system, there's two different avenues to pursue for the science. One of them is to study an individual planetary system to death and kind of learn everything that you can about it. And the other one is to get a census of different planetary systems and how many there are. Given the fact that Kepler wasn't going to be able to find planetary planets with orbits of 100 years. Or something like that. It was only really designed to find things on a year orbiter slightly longer.

• 35:16Speaker 03

  And so, once Kepler had its catalog put together, then there was a subsequent study that said, okay, for every planet that we find, how many do we miss of a given size and a given orbital period? And so if we find one Earth-like planet, that's going to correspond to, you know, maybe 1,000 Earth-like planets that didn't show up because of the noise in the system or didn't show up because of the, that happened to fall in a gap in the data or something like that. So those things can be accounted for after the fact. The moral of the story is that it appears that roughly a third of stars are going to have a planet

• 35:59Speaker 03

  similar to the Earth in an Earth-like orbit.

• 36:04Speaker 03

  Now, it's not clear if those planets also are going to have a Jupiter. Or if that's, so if that's going to be like an inner planet for a system with,

• 36:15Speaker 03

  where most of the planetary mass is out in the distant part of the solar system? Or if that's going to be the outermost planet in a system, what I call Kepler planetary system, a Kepler-like planetary system, where you have lots of planets that are all in close in orbits?

• 36:31Brian Keating?

  Yep.

• 36:34Speaker 03

  So, this was some of the low hanging fruit certainly appeared lots of hot Jupiters. In fact, for the first year, that's all that we were kind of able to.

• 36:46Speaker 03

  Early exoplanet science had a lot of retractions and so.

• 36:51Speaker 03

  They were hesitant, the science team was hesitant to put a lot of new discoveries out there with, without really vetting the results to a high degree. And so for several months, our only discoveries were more hot Jupiters, which had already been, you know, it was, they were already 15 years old by the time Kepler launched, and so it wasn't really newsworthy. Not as newsworthy as it could have been, but by the time the first year had wrapped up. There were like several hundred planetary systems, some of them with multiple planets in those systems. And then the fire hose kind of opened up and it took us several years before we got our heads above the water again.

• 37:31Speaker 03

  So this Kepler 11 was an example of the type of system that the mission found. This is what it looks like in raw data. So raw data at the top, you have. The temperature fluctuations because the spacecraft is changing its orientation every few months. It goes into safe mode and so the whole system heats up and you have to remove all of these artifacts. You'll see that the overall variation in the photometry, like the brightness of the star. On the top is about 1%, so you have roughly 1% variations just because. You're of the instrument and of the star spots and things like that. But then, once you remove all of those effects, then you get the thing at the bottom where the variations are.

• 38:15Speaker 03

  More like a 10th of a percent or. One one hundredth of 1%, you can see much, much smaller deviations. The rain that's coming off of the, of, off of the bottom of that, those are individual transits. And so this is six planets, there's six different orbital periods and six different transit depths. That are found in these data and where the transits are located is seen on the bottom of the different dots. The different colored dots show, okay, the yellow planet is transiting here, here, here, here, here and here. And the blue one is transiting in these other places. So it's really quite remarkable, the sensitivity that we could get with the spacecraft. And this is with an early pipeline, the pipeline improved over the course of the mission's lifetime.

• 38:58Speaker 03

  So the data analysis pipeline. One of the things that we saw with Kepler is that the data are good enough that we can see the planets actually interacting with each other gravitationally. So you'll have multiple planets in a system, they interact with each other gravitationally. That causes their orbits to change slightly. And we can see the deviations from their orbital period. From one transit to the next, how those mutual gravitational interactions affect the orbital periods of the planets. So these are called transit timing variations. This was the practice problem that I had as a graduate student. Was to figure out, basically do the, how big are these transit timing variations going to be? How would they be detectable?

• 39:41Speaker 03

  What, how does it depend upon the mass of the participating planets and things like that? So it was supposed to be an eight month project that, before I got back to doing black holes. But we found that it would be, we would be sensitive to Earth mass planets. Using this technique. And right at the time that we finished our first paper describing this effect. There was a group that published a list of transit times. And my advisor told me, it's not very often that the data that you need to use, like to apply your theory to, just fall in your lap. And so it might be a good idea to analyze these data. Because they're here.

• 40:21Speaker 03

  Instead of, you know, analyzing hypothetical data that's going to come apparently. So when was the black hole at the center of the galaxy image? Like about six years ago, something like that. So it would have been a decade into the future, or you can have something that's in your lap today. So that ultimately, that study is what basically gave me the motivation, or gave NASA the motivation to bring me onto the science team. Because at the time that this, they requested new people to join the, the mission. I was the only person who had done an analysis like this. And it was one of the things that they're like, oh, this is something that would be well suited

• 41:02Speaker 03

  to the Kepler mission is finding, measuring the planet properties and finding new planets in systems where you can see these variations in orbital period.

• 41:13Speaker 03

  Some of the weird systems that Kepler found, like Kepler 36, for example. So now this is an artist rendition. You can tell it's an artist rendition because you can see the sky in this image. But the Kepler 36 system is two planets that orbit about 10% apart from each other. So one of them has a 10-day orbit and the other one basically has an 11-day orbit. It's actually 11 and 13 days, but their orbital distance is 10% different. And their densities are almost a factor of 10 different. So the inner planet is more dense than the Earth and the outer planet has a density that's 10 times less dense than the inner one. So there's a huge discrepancy in the densities of these two planets, even though they're

• 41:57Speaker 03

  right next to each other in the system. And they're so close together that if you were standing on the surface of one, this would be the image that you see when the other planet passes overhead. So, in fact, they're so close together that you can actually measure dynamical chaos in the system. So chaos being that if you make tiny changes to the orbits of either one of these planets, it actually fairly quickly affects what the future for that system holds. There's chaos in the solar system, for example, where small changes to the positions of the planets can result in very different outcomes.

• 42:36Speaker 03

  If you were to displace Mercury by less than a millimeter, then the chances, then there's a, it might put it on a path where it would collide with Venus or with the Earth in the future. There's a, even now, there's basically a 1% chance that Mercury collides with the, basically disrupts the inner solar system every billion years. And so this planetary system, Kepler 36, it has that same effect, except that instead of having it every billion years where these things would be manifest, it's like every few hundred days. So it's really quite a chaotic system in terms of how it flops around from certain orbital states.

• 43:22Speaker 03

  Another thing that was found in the Kepler mission was it found a lot of really, really short period planets. So planets with orbital periods less than a couple of days. And the famous one for that one is Kik 1255. The telephone number for this one is a bit longer than that, but I can only remember the first four numbers. It's Kik 1255, Pi E, something like that. But it orbits every few hours, like six hours or something like that. And it's so hot that it's melting or vaporizing the rock off of the surface and forming a comet tail that's made out of rocky material instead of a comet tail that's

• 44:04Speaker 03

  made out of water like it would be in the solar system. So you can see basically the comet evaporating due to the intense light from the star. So Kepler also found planets that orbit binary stars. So you'll have, there's a famous saying that three out of every two stars in the sky are in a binary. And so this was the first time that we saw a planet, you'd have a binary star and there was a planet going around both stars at the same time. So it's not going around one of the two stars. That had been seen before where you have a binary star and there's a planet going around one of the two stars. This was the first time that there was a planet going around both stars simultaneously. And there's been about a dozen of these that have been found. So

• 44:48Speaker 03

  it was also another remarkable thing. And given the fact that there's, what, 100 billion binary star systems in the galaxy, that these are probably pretty common. They're hard to find, but they must be pretty common. It found, like I mentioned, planets that are smaller than the moon. Kepler 37 is an example of that. Found planets that are in the habitable zone of their host stars where if you were, you could imagine liquid water living on the, or like existing on the surface of those planets. So it really did provide a huge number of discoveries. So if you look at the

• 45:29Speaker 03

  This isn't the final catalog, but it's pretty close to the end. There's like 4,000 planets that Kepler had found. And they kind of run the gamut of orbital periods that are less than a few hundred days. So basically like from Earth's orbital period and shorter. There's just huge numbers of planets and most of these planets aren't like the planets in the solar system. They're not rocky, they're not really Neptunes either. They're like somewhere in between. There's like big, big versions of Earth or small versions of Neptune is kind of the, the common thread between the two. So those are basically the discoveries that Kepler made. I'll point out, one of the issues that you have with this survey,

• 46:12Speaker 03

  because there hadn't been exoplanet systems discovered when they were designing the survey. So you can't rely on, oh, here's what we, you can get, after you run the mission, you can say, oh, here's what we should have done if we really wanted to make a lot of discoveries. But you can't know that upfront. So causality hasn't been violated yet. But the, the Kepler survey, because you have to have a large number of targets in the field and you have to observe continuously so that you don't miss a six hour transit of something like the Earth. The Kepler field of view was something like this. So it was surveying all the stars along some line of sight. What that means is that most of the stars, so here's the dividing line. That's half of the stars are closer to the Earth and half of the stars are farther.

• 46:57Speaker 03

  Like there's half of the stars in either side of that cone. And so the average distance to the stars in the Kepler survey are pretty far. Hundreds or even thousands of light years. And so they're really dim and dim targets means that you can't really follow up very easily from the ground. So like one data point when, for a given target would be an hour on Keck. And Keck is the biggest glass and the highest resolution spectrograph that, that the planet has, like the Earth has right now, or pretty close to it. And so it's really expensive to do follow up measurements to these planets. But now that you've run the Kepler mission, you can say, okay, we know what kinds of planets

• 47:40Speaker 03

  there are. We want to see the brightest ones. We want to find the best targets to do follow-up measurements, which is not necessarily going to be the Kepler sample. And so that, the Kepler results inspired the TESS mission, and the TESS mission does an all-sky survey, so it's looking everywhere. And so this is, if you can look all across the sky, this has the same number of stars in this circle as exist in the cone, except now the typical distance is significantly closer. And so the stars will be 10 times closer, which means they're going to be 100 times brighter, which means that they're significantly easier to follow up from the ground. So the TESS mission looks like this. It's kind of a follow-up to the

• 48:21Speaker 03

  Kepler mission. These are basically just cameras that are not too dissimilar from what you would see at the sidelines of a sporting event. And it has four overlapping fields of view, and then it just clocks around in like a flower-shaped pedal in order to see the nearby stars. And TESS has discovered its own several thousand planet candidates following on the heels of Kepler. And these ones are ones that we can follow up with with ground-based observatories to an easier degree than we could with the Kepler mission. Ultimately, the Kepler mission itself, due to this part, met its demise. So this is a

• 49:03Speaker 03

  reaction wheel. In order for Kepler to have really good data, it has to point very, very precisely, precisely to the degree of if you were, if you had Kepler, the telescope, in San Diego, and you were looking at Washington DC at the Washington Monument, if you were to go out of the nominal pointing direction, far enough that you've gone from the top of the Washington Monument to the bottom of the Washington Monument, you would no longer have science-quality data. So it's like micro arc second type things, it's small fractions of a degree. Before you're no longer in what's called fine point. And so the data are no longer good enough to do science observations.

• 49:48Speaker 03

  So in order to keep the attitude of the spacecraft, so the orientation of the spacecraft consistent, they have these reaction wheels. And they'll spin around. If the spacecraft starts to drift in some direction, then the reaction wheels will spin and it will cause it to rotate back in the other, in the other direction. Counteract micrometeorites and radiation pressure and all sorts of stuff that affect the spacecraft. Well, one of the reaction wheels started to fail.

• 50:15Speaker 03

  And so they turned it off, used the backup, it had one backup. You need three reaction wheels in order to steer.

• 50:22Speaker 03

  So they brought up the backup, the backup started to fail and then. The backup one failed and then they went back to using the other one and then that one failed as well. So there were two reacting wheels that failed. Basically, six months after the expiration date. Kepler was supposed to be a three and a half year mission, it went for four years. And then it couldn't maintain fine point anymore. So it kind of was, it wasn't completely adrift, they still had fuel, it has thrusters as well. And so they very quickly sent out a solicitation to the overall science community. Saying if you have a slightly defective billion dollar telescope. Or half a billion dollar telescope, what would you point it at?

• 51:03Speaker 03

  And they had one, oh, and you have one month to get back to us and you're going to be competing against Hubble and Spitzer and Fermi and all these other ones.

• 51:14Speaker 03

  So while that was going on, while NASA was basically trying to come up with a science case for what to do with the spacecraft now that it wasn't functioning. The way that it was designed to function. The people at Ball Aerospace. So, and Ball Aerospace is the contractor that built the spacecraft. It's actually, at the time that Kepler was selected, they still made the canning jars for food.

• 51:37Brian Keating?

  Yeah.

• 51:38Speaker 03

  So Ball jars and Ball Aerospace are the same parent company. But by the time Kepler launched, they had spun off the, canning jars was a little bit less lucrative than spacecrafts. So the engineers at Ball said, you know, if we could orient the spacecraft so that it was pointed in a certain direction relative to the sun, then we could use the solar wind to help keep it stable. And that would allow us to have better pointing for longer periods of time. And the estimate was that they could basically get 80 days, not quite three months, but almost three months of consistent, like, science quality pointing with really small adjustments to the spacecraft using the thrusters.

• 52:22Speaker 03

  So basically, when they got down to two reaction wheels, they could orient the spacecraft in a given direction, but they couldn't prevent it from rotating around its main axis. And so they used the solar wind to help mitigate the rotation around the axis. And so then it ran for another, basically like four additional years, almost four and a half years in this K2 mode. So they repurposed the spacecraft, like, gave it a new mission designation as the K2 mission. And then that operated for several years after the original Kepler mission ended.

• 52:56Brian Keating?

  How did you compare in terms of science goals?

• 52:59Speaker 03

  Um, it was not the same. It did provide a number of important discoveries that I, some of my outline in the book. My favorite planetary system is the WASP-47 planetary system. And it did major work for WASP-47. It discovered new planets in that system that really bucked a lot of trends that people had been examining. So myself, I had made the claim for a long time that hot Jupiters are lonely. So Jupiter-mass planets on three-day orbits were...

• 53:31Speaker 03

  Didn't have nearby companions, which constrains how they can form. Because if you have nearby companions, then that allows different formation mechanisms. Where if there are none, then that implies more violence in the history. And so I had published a paper that was basically saying, you know, when we analyze almost 100 is like 60 something. Hot Jupiters, we don't see evidence for nearby companions. But K2 studied the WASP 47 system and it found nearby companions. Like companions on nine day orbits or something like that. And so that really, that broke the mold in terms of hot Jupiter formation. It demonstrated that you can actually have multiple formation mechanisms to make a hot Jupiter.

• 54:15Speaker 03

  So WASP 47 is my favorite, Trappist, the Trappist system was also studied with K2. But in terms of, so it had good data. The data were comparable quality is like 40 parts per million instead of 20 parts per million. What the K2 mission lacked was it wasn't a uniform, long-term survey of a sample of targets that was consistent for a long period of time. And that was, my science was really most geared towards the original Kepler mission with four years of continuous data. And so when K2 kind of spun off, I didn't really follow the, I didn't follow that branch of the science team onto the K2 mission.

• 55:01Speaker 03

  My, myself and the working group that I was part of just stuck with the original Kepler data for our analysis. Cause we were doing the cool stuff and.

• 55:15Speaker 03

  So, and then ultimately Kepler ran out of fuel and that was the final, like, once it runs out of fuel, then it just starts tumbling and there's nothing you can do about it.

• 55:23Brian Keating?

  And the fuels used for the reaction wheels, or what was the fuel?

• 55:26Speaker 03

  So the fuel was used to, um, so reaction wheels are really small corrections and the fuel is for thrusters in order to like do bulk motion of the, um, of the spacecraft. So they had to fire the thrusters, one to be able to point the telescope or the antenna back towards the earth to downlink the data, but they also had to use the fuel in order to keep the spacecraft, um, in the right orientation. Uh, so what they would do is they would fire two thrusters in opposite directions and the mismatch in the thrust between the two, uh, the two thrusters gave a small correction, like a first order correction to what they would be capable of doing.

• 56:05Speaker 03

  And so that's actually an expendable fuel, uh, hydrazine. And when that ran out, then, then there was no longer a way to, to point the spacecraft.

• 56:15Brian Keating?

  Got it.

• 56:20Speaker 03

  So that was basically the, the Kepler mission, kind of in a nutshell. It, um, really, it, it changed the way that we view the solar system because solar system is pretty well constrained. The Nice model is the, you know, current standard, um, history for the solar system. Neptune formed closer in and then it, um, the gas giant planets expand after the gas dissipates. That causes the Neptune to plow into the Kuiper belt. That captures a bunch of objects into mean motion resonance like Pluto, the non-planet that should never been a planet in the first place.

• 56:55Speaker 03

  And it also scattered a bunch of stuff into the inner solar system, causing like delivering water to the earth and, um, Jupiter may have, now this is not part of the Nice model, but there's a called, something called the Grand Tach model that explains why Mars is such a wimpy planet, um, compared to Jupiter and Venus, or compared to Earth and Venus.

• 57:13Brian Keating?

  What is that word, Nice that you're using?

• 57:15Speaker 03

  So the Nice model, um, so that's Nice, France is what it's named after.

• 57:20Brian Keating?

  Not an acronym.

• 57:21Speaker 03

  Yeah, so it's the Observatoire de la Côte d'Azur. That Alessandro Morbidelli is the guy who kind of developed the Nice model. So he basically, it's really interesting. He uses the orbits of the small bodies in the solar system. So like, what would effectively be test particles? He uses their orbits to constrain the dynamical history of the solar system. And so you look at how many objects are there like Pluto in three to two mean motion resonance with Neptune? They're called plutinos. And there's hundreds of those compared to things that are scattered. So you have a bunch of things that are scattered into high eccentricity and high inclination orbits. You have a bunch of things captured into resonance.

• 58:07Speaker 03

  You have gaps in the asteroid belt that come from Jupiter's orbit.

• 58:12Speaker 03

  Similar to gaps in Saturn's rings. You've got a population of comets that come into the inner solar system at certain rates. And so all of that can be used to constrain the history of the solar system. So where did Neptune have to form? And how long did it take to migrate out? And why did it stop? And when did it stop? And how many objects were scattered into different kinds of orbits as a consequence of that? And why is, so one big question for planet formation theory is why Mars is so small? It's only a 10, a 10th of the mass of the Earth. When most, if you just ran planet formation scenarios with Jupiter where it's located. You most of the time get planets bigger than the Earth where Mars is located.

• 58:54Speaker 03

  And so the fact that Mars is so small was a mystery. I mentioned it's not part of the, the Nice model is really the expansion of the gas giants orbits and the Neptune's migration outwards and then the effect that it has on the comets.

• 59:10Speaker 03

  But there was an idea called the Grand-Tac model where Jupiter actually started migrating inwards. And then it captured into a specific orbital relationship with Saturn, which then pulled it back out from the brink. But as it moved in, it plowed into the asteroid belt and depleted the asteroid belt and the region where Mars formed. And so there was less material for Mars to form from. So that's not science on it.

• 59:35Brian Keating?

  The, you know, the formation of a moon.

• 59:38Speaker 03

  It would have been before, because you didn't quite have the same, you didn't quite have the Mars sized objects around. So it was, you still had to have the gas disk presence, present at the time. So I guess a little bit of history of the solar system. The gas giant planets form very quickly. They form in a few million years because they have to form while there's still gas around. After the gas dissipates, then, so I guess the presence of the gas, when you have small rocks, like rain, apples and very small rocks, things that float around in the, in the gas, the, the small rocks, their orbits will circularize because of friction with the gas.

• 1:00:21Speaker 03

  And it's not until the gas disk dissipates that their orbits become eccentric and start crossing and then they start smashing into each other. And so Jupiter forms well before the Earth forms. Because the Earth formation requires that things be able to collide, the orbits of the small objects start crossing and you get collisions. So the Grand Tach Model that depleted the inner solar system happened while the gas disk was still around. And then after the gas disk dissipated, you have a region where there's just less stuff to form Mars from. And then, and Jupiter, I'm sorry, and Earth and Venus all form from a kind of rich planetesimal environment. Now that's, it's not settled science, it's, but it's an explanation that is viable.

• 1:01:05Speaker 03

  You know, it can reproduce everything that we observe. And it explains why Mars is such a wimp.

• 1:01:12Brian Keating?

  Let's see, Jason, we have tons of questions. I want to start off with the first one. I'm someone who is not a wimp. Peter O'Halloran is a good friend of mine from Ireland. I wonder, I've not asked him where he's from. My family, my stepfamily's from County Cork. Peter asks, Kepler's transit method was remarkably effective at identifying exoplanets, but it relies heavily on precise data interpretation. How did you account for false positives like solar activity, stellar activity on the host star?

• 1:01:44Speaker 03

  That is a great question. So there were people who really spent a lot of time getting to know the personality of the instrument. So stellar flares and things like that were a bit easier to deal with.

• 1:01:59Speaker 00

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• 1:02:29Speaker 03

  Then like instrumental systematic effects. I guess I should say not necessarily easier to deal with, but there's different ways of dealing with them. So if you have something that is an instrumental effect, like, for example, suppose that a small dust grain hits the telescope, breaks off a piece of paint that then floats across the aperture and reflects sunlight down into the aperture. So all of the stars, like the whole field of view gets brighter all of a sudden because this reflection off of this paint chip. That you can deal with because you say, oh, all of the stars are getting brighter all at once. Therefore, that's not a planet transiting the star. So there are a bunch of those kinds of things that people had to deal with. Temperature fluctuations. They had a thing called rolling

• 1:03:13Speaker 03

  band, which was like crosstalk in some of the wiring that would sweep through some of the CCD chips. Not all of them, but some of them had the rolling band. So they had to deal with all of those kinds of things. And then with individual stars, you can see flares, you can see pulsations. So you can, when you're taking all these data,

• 1:03:37Speaker 03

  You know that the transits are going to be short, they're going to be localized in time. Where if you have stellar pulsations like P-mode and G-mode is the, P-modes are pressure waves, like sound waves that are propagating around in the star. And G-modes are gravity waves, so those are like big floppy fluctuations of the star's pulsation. Those things you can see by looking, by just basically saying, what are the frequencies that the star is pulsating at? And you can identify how it's ringing. So you can separate those. Flares, they have a particular profile, so you can identify those profiles and say, okay, this is a flare, this is not. It does, it's pretty easy to find planets like Jupiter, because those have enormous signals.

• 1:04:21Speaker 03

  You have 20-part-per-million precision, and you're getting a 1% deviation. So you're, like Jupiter-mass planets, you can resolve really easily. The Earth-sized ones were the hardest ones. So some of the things that they did, not necessarily to confirm specific planets, but rather to be able to make claims about the population of planets,

• 1:04:44Speaker 03

  is that they injected fake data into the, into the real data. So they, they had the real data, and they injected fake transits into the real data, and then said, okay, how frequently do we recover these planets that we injected them in? I know that LIGO does the same thing, where they'll put fake gravitational wave signals into their, into their instrument, and then see what, if they can recover them. Because then you know, for every planet that we find, we, we miss three, or we miss one, or we miss a half of a planet for every one that we find.

• 1:05:18Speaker 03

  So, after, there are also, in some cases, you want to, there, there were actually astronomers that study stars on the mission. And so they were looking at, you know, how do the star spots evolve? And where do, you know, can you get the stellar rotation from them? And those are other things that you can separate from.

• 1:05:41Speaker 03

  From the data, if you know kind of what you're looking for, and then you can match the behavior to the data.

• 1:05:46Brian Keating?

  Ah, okay.

• 1:05:47Speaker 03

  So the technical term, like you can have like a match filter. They had like wavelet transforms of the of the time series in order to say, oh, this is what stellar rotation looks like or star spots look like. And so we can map them and then separate them out from.

• 1:06:00Brian Keating?

  Yeah, very good. Okay. S.S. Scannigan asks, what are the most interesting anomalies with exoplanets?

• 1:06:07Speaker 03

  Um, so I think, which ones do I care about the most? Because those are the ones that are the most interesting. I think that WASP 47 was definitely up there because it was the counter example to lots of different things. Having a hot Jupiter with an Earth-sized planet in a nearby orbit. I think the really short-period planets, the ultra-short-period planets that have orbital periods less than about two days, you know, down to four hours, I think. It's either four or six hours is the shortest orbital period of a planet we ever found. I mean, that's, that is so close to the hot star that the mind boggles at the, how, how that planet gets, gets there.

• 1:06:51Speaker 03

  We still don't know how some of these planets get into those orbits. So that was an interesting anomaly. There was, in stellar astrophysics, an interesting anomaly, which is, we call them heartbeat stars now. So that is a system, the first one that we discussed as a science team, we thought it might be a black hole that was transiting the star. So we thought that the star was there, and then a black hole was going in front of it, and the black hole was lensing the star and making it get brighter. Because the star would, it would go along, it was like wiggling, wiggling, wiggling, and then it would get really bright, and then it would come back down and wiggle, and then would wiggle some more, and then get really bright, and then come back down again. And it turned out that what it was, was two massive stars on really eccentric orbits.

• 1:07:35Speaker 03

  So they'd come in and have a really close encounter, and then they'd go back out, and they'd come in and have a close encounter and go back out. And when they had the close encounter, their gravitational fields distorted their shape, and the reflected light was just bouncing back and forth between them, and so they got really, they kind of heated, warmed each other up. And so that was causing this change in brightness, was that the stars were getting, the profile of the star was getting bigger as they were stretched out horizontally. And the and the facing surfaces were getting hotter as they came close together. And then as they retreated from each other, then they just sat there and sloshed back and forth like a water balloon. Like you can imagine hitting a water balloon with something and it doesn't pop, but it just sits there and sloshes around.

• 1:08:18Speaker 03

  And so these stars would come in, they would distort each other, and then they would slosh for the rest of the orbit. And that was causing the little wiggles and then they come back in and then they have another close encounter. I mean, it's kind of like the, you can imagine that, you know, the epichiratic universe that where it's like, oh, every once in a while, these two brains come together and that gives you a new big bang. That's basically what, it's a small version of that with these two big stars where they come close together and then they start oscillating. So heartbeat stars, that was the, one of the examples, but there were, ended up being several dozen stellar pairs that had that kind of behavior. That we only saw with the Kepler data. So that was, well, I guess another thing, continuing on with the stellar astrophysics,

• 1:09:00Speaker 03

  is we could actually see the rotation of the core coupled to the rotation of the photosphere. So you, stars, the cores of stars don't always rotate at the same rate that the outer layers do because it's a fluid. And so you can always have, you know, things rotating at different rates. But you can see in the Kepler data, when stars, when the stellar core finally is able to kind of drag the photosphere up to, to couple to it. And so then it's rotating as a single unit instead of, or roughly a single unit instead of having the core rotating at a different rate than the out, outer layers. That was, when I first heard about that, I had to sit and ponder it for about 15 minutes before I could come to grips.

• 1:09:45Speaker 03

  Like what is it that's going on? How, and, because it really shows up very, fairly clearly, the different rotation rates. And it, and it's a fairly fast transition as well. Like it's not coupled, it's not coupled, it's not coupled. And then it is, and then it slows down. Very, it's Kepler data in, is, it's, it's no joke, the astrophysics.

• 1:10:05Brian Keating?

  All right, we're reaching the end of the hour, but let's keep going. A couple more questions for you, Jason. I'm really enjoying it. You always get to ask questions on this channel and don't forget to, uh, to subscribe to the channel and leave a like, comment. You know, these things are necessary. It's always embarrassing and humiliating to have to ask for them, but, uh, but it is something that sort of the algorithms that are more complex than the Kepler data analysis pipeline requires of us. And if you do join and if you do have a .edu email address, you're guaranteed to win one of these beauties. If you live in the United States at least, a .edu email address will get you a meteorite, which is a fragment of the early solar system. And I owe one of these to Jason. I give one to all my guests as well.

• 1:10:46Brian Keating?

  So hopefully Jason will be together maybe next year and I'll come visit, you come visit here maybe, and, uh, give you one of these beauty meteorites. So, but if you have a .edu email address in the US, go to briankeating.com/edu. And if you have a non-EDU email address, I still give these out. I select, uh, 10 people each month to give these away to on the mailing list. That's a briankeating.com/list. Okay. Slam RN. I read that the position and sizes of our rocky and gas planets is very unusual in our solar system. Is that true?

• 1:11:19Speaker 03

  We don't actually know. So it's unusual compared to the Kepler planetary systems, but, uh, systems like the solar system were right at the edge of what Kepler was able to detect. So it could detect Earth-like planets in Earth-like orbits, but it wouldn't be able to detect like an Earth-like planet in a Mars-like orbit. And so we don't have a good census of 30-year gas giant orbits and one to two-year Earth-like, you know, rocky planet orbits. So it's possible that, um, so we know that between a third and a half of planets of stars have planetary systems like the ones that Kepler found.

• 1:12:00Speaker 03

  It's possible that the remaining two-thirds or half of the planetary systems are like the solar system. Or it's possible that they're not like the solar system at all. My suspicion is that the balance of stars will have solar system-like planetary systems, but that's just conjecture on my part. Um, it's not, um, we don't have data in, that's the hardest part of parameter space to probe. So the hardest, like finding a true Mars is

• 1:12:31Speaker 03

  Like, that's gonna be exceptionally difficult. So, a Mars-sized planet on a two-year orbit, and finding a true Neptune is another very difficult thing to do. Like, the direct imaging surveys that are going on, those are to find basically Jupiter-sized planets that are warm, that are still cooling from their formation, where Neptune is cold, and it's farther out, and it's smaller. And so, finding a true Neptune is, those are kind of the benchmarks, the next set of benchmarks for a planet.

• 1:13:05Brian Keating?

  I see. Okay, good. Okay, next question comes from George Anderson. Let me put that up there. "Besides light and dark, can Kepler's data be used to figure out what atmosphere, what the atmospheres of these exoplanets contain?"

• 1:13:21Speaker 03

  No, it's not really a good instrument for doing that. It's, that, what Kepler does is identifies the targets that you then follow up with the James Webb Space Telescope, or with Hubble, or something like that, or with a ground-based telescope. So, it's really kind of a discovery thing, and then you follow up with instruments that are more specifically designed to measure those kinds of properties. In particle physics, the analogy would be that when you have a proton collider, like what Fermilab has in the Large Hadron Collider, that is to discover new particles. But if you want to actually study the properties of individual particles, you want to collide electrons or muons, because protons are messy

• 1:14:03Speaker 03

  objects. And so, you can discover things, because you can exploit the fact that they're messy in order to see things that you wouldn't be able to find otherwise. But then, once you find them, you want to use electrons or muons, because those are, those you can tune the properties of the beam much more carefully than you can with a proton collider. The same thing happens with exoplanets. Kepler finds them, and then you turn it over to other instruments to study.

• 1:14:28Brian Keating?

  Interesting. Okay, a couple more questions before we wrap up for the long weekend ahead. This one comes from a longtime friend of the channel, Nuno Marco, who asks if a little, whoops, let me put it up there, if a little black hole transit star, what effect would you see effectively? And you did mention that. I should also point out, the first extrasolar object detected using some of these methodologies was a pulsar, right? A black hole around a pulsar, right?

• 1:14:59Speaker 03

  Yeah, so there was a set, there was a binary. Was it a binary pulsar? There was a pulsar. I don't remember if it's a binary. I thought it was a binary. But I can't confirm that off the top of my head. So there was a pulsar that was discovered in the, or that was being studied in the late 80s by Aerosibo, the Aerosibo Observatory. And there they found.

• 1:15:20Speaker 03

  Planets, three planets orbiting that that pulsar. So those were the first exoplanets discovered. But we always, so the, the language you'll hear is exoplanets orbiting a sun-like star. Because the pulsar planets probably formed after the stellar explosion happened and it was a subsequent debris disk or disk that that the planet, so they're basically like second generation planets and not planets like the earth.

• 1:15:47Speaker 03

  The.

• 1:15:51Speaker 03

  I can't remember the other half of the question. So that was.

• 1:15:53Brian Keating?

  Would you see that? What effect would you see? I think you answered it. Yeah.

• 1:15:56Speaker 03

  So I will say that real quick with the, with the black hole. I don't know what would happen with the black hole, but we did see at least one instance of a white dwarf that transited the host star. And there, when the white dwarf passed in front of the star, the gravitational field of the white dwarf lends the, the the main target star. And so it actually did get brighter when the white dwarf went in front. And, and it got dimmer when the white dwarf went behind because the white dwarf is hotter than the regular star. So. But there, there was, we did see the kinds of lensing that you would expect from a black hole.

• 1:16:29Brian Keating?

  Hmm. Interesting. Okay. Last question again comes from Peter. And he's getting extra credit today. Uh, this is about Tabby's star. What's the, um, current hypothesis, prevailing hypothesis? Things have ranged from stellar instability to comet swarms or Dyson spheres. I, I like that because Freeman Dyson was my first guest on this podcast. So what do you think is most plausible explanation, Peter wants to know?

• 1:16:53Speaker 03

  Uh, I honestly don't really have a good idea about what that would be.

• 1:16:59Speaker 03

  Stellar variability.

• 1:17:03Speaker 03

  It doesn't, that seems a bit of a stretch.

• 1:17:08Speaker 03

  So I think that having like a cloud of dust or something like that, you know, cloud of debris is plausible.

• 1:17:19Speaker 03

  But it is kind of weird. I haven't spoken with Tabby lately to find out what the state of things are with that discovery. I remember-

• 1:17:29Speaker 00

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• 1:17:58Speaker 03

  When it was discovered, a lot of things, a lot of really interesting systems, when we looked at them, they looked like noise. They're like, that's some kind of weird object. And that was one of them. It's like, that can't be real. That's something's going on with the, like Kepler's on crack. And so we're going to just ignore that.

• 1:18:14Brian Keating?

  I always say, just say dust. Yeah. That's the most-

• 1:18:17Speaker 03

  So, yeah, it wouldn't be, it wouldn't be surprising. I mean, stars are unusual. And you know, so that's one out of 100,000 stars that has this really weird behavior. And that's one of the advantages of having a large survey is that you can find unusual systems.

• 1:18:34Brian Keating?

  Absolutely. Well, Jason, this has been a blast for me, many other people. I just only wish the late, great Carl Sagan was around to see but read both this book and see the wonders that are hiding in the heavens. You know, congratulations on a phenomenal book. Really a detective story, a personal story memoir, but also, you know, kind of representing the best of what science has to offer the human, the human spirit. I think this book is a, is a great introduction to what, what it's really like to be an astronomer, to be a scientist, working on the cutting edge of, and all that entails. And so I thank you for this gift of a book. And it makes a great, as I said, holiday gift, Christmas

• 1:19:15Brian Keating?

  gift, wherever you are, wherever you may celebrate. And Black Friday's coming up. So, Jason, thank you so much for being a guest on the Into the Impossible podcast.

• 1:19:24Speaker 03

  Yeah, thank you. It's my pleasure.

• 1:19:26Brian Keating?

  All right, we'll take the last couple of seconds to just let you guys know what's going on with the channel. Again, I hate to have to do it, but I always ask to subscribe and actually this, join my mailing list. These things really do help. There, I got a thumbs up for my Apple Studio Monitor. It's been a wild ride this year growing the channel. Almost doubled in size again. This rate will be bigger than, you know, Mr. Beast in a couple of decades. I hope, in all seriousness, that you guys are enjoying this content. I do love to do it. I don't really, you know, I get some amount of money from doing it, but that's not really what I do. I just really love communicating, giving back to young

• 1:20:08Brian Keating?

  people especially, but even older people that don't have a chance to, you know, didn't have a chance to go to college, or maybe didn't get a chance, went to college, didn't get a chance to study something that really would have energized their soul, like studying physics and astronomy. And by having great guests like Jason on, I hope that I encourage you to never stop being curious. ABC is my motto, always be curious. And I really do hope I can encourage you all to do that. And I have a lot of great guests coming up. Brian Greene is coming back up, everyone's favorite astronomer named Brian, physicist. Now, my kids slightly prefer me, I suppose. Then there's Neil deGrasse Tyson, who's coming back on to talk about his new book, or his update to his book about Merlin's Guide

• 1:20:52Brian Keating?

  to the Universe. He'll be on in a couple of weeks. I've got a couple of major appearances I'm going on. Just got linked up with my friend Andrew Huberman again to record a podcast episode of his podcast. And I do want to talk to him about all the delightful similarities between a telescope and the human eye. And he's an expert in that. But also talk about exoplanets, and what it would be like to get the HLP, the Huberman Lab protocols on WASP-37 or whatever. You know, how would other organisms react to the protocols that he suggests? Or would they even have their own? That might be even more interesting. I also have a buyer's guide, and not that I get any money. It's not my personal buyer's guide. You can go to Brian Keating.

• 1:21:36Brian Keating?

  com/telescope. I think that takes you there. Let me see if that will work. And you'll get a buyer's guide for telescopes for the for the holiday season as well. That will hopefully give you the gift that I always say this little gift, this little $50. This one costs $10. But but the telescope that I got, my mom helped me buy, split the money with me when I was 12, 13 year old young man in Westchester County. That really did, that $50 investment, really turned out to enable who I am today. And the kind of science and work that I do helped me get to build this podcast up from nothing

• 1:22:15Brian Keating?

  to over, you know, getting over 350,000 subscribers and all the platforms combined. And of course, write my my first book, Losing the Nobel Prize, which describes how my journey into astronomy took place and kind of the perils and pitfalls along the way. It's a memoir of what it's like to be a scientist, very similar to Jason's in some way. But Jason's very technical and excellent at providing deep insights into what it really takes to be an astronomer and work at the cutting edge. And so I'll have many more guests. Let me know what you think about these live streams in the comments on the video. I do like to do it. There's some effort and there's always a little bit of a of a panic right before you go live. It's like, you know, being a pilot or something. There's, you know, hours of boredom.

• 1:23:00Brian Keating?

  Hopefully not hours and hopefully not boredom, but then, you know, punctuated by sheer terror as the, you know, software decides to glitch or, you know, you get some pop up or text message from my wife or something. So so these things are, you know, kind of a little bit more stressful than an ordinary podcast interview, but but they're also really fun. It gives you a real time, live chance to ask questions. So let me know who you'd want me to interview on the podcast. Leave that on the comments and who you'd like to see, especially live. I have had a great conversation with Jan LaKoon, who is Metta's chief AI officer scientist, and he's also professor at NYU. You're gonna love that conversation. So, yeah, please do subscribe. I know it sounds cliche, but it is important. And even, you know, I learned going on Diary of a CEO,

• 1:23:45Brian Keating?

  that episode will be out Monday, they tell me, Monday, which is December 2.

• 1:23:51Brian Keating?

  Crack of dawn here in the US or in California. So be sure to check that out. But Stephen's got 8.25 million subscribers as of today. You know, that'll surely double on Monday. But the, you know, thing that he does every episode, right up front in the first 10 seconds is he asks you to subscribe. And he always laments how few people are subscribed to the, to the Diary of the CEO podcast. I'm like, come on, you've got, you know, two orders of magnitude more than, than most of us. But he's such a great human being. It was so much fun to have a real scientific discussion for him and for me as well, to bring it to the masses. And like I said, I'll be hopefully doing the same with a completely radically different audience.

• 1:24:32Brian Keating?

  This year I've got interview requests to be on with, as I said, Andrew Huberman and then Jordan Peterson. And this episode with, with, with Stephen Bartlett was really just a delight. You know, it was supposed to be two or three hours, ended up being four and a half hours. We'll see how much of that, you know, made it through the cutting room floor. And, and it's just so much fun to take you all on this ride. And I think now more than ever, we see the colleges under fire and kind of the nonsense that goes on at many universities. Not necessarily here, but, but, you know, the kind of craziness that goes on. We just want to learn science. We just want to connect with science, not with politics. We need a safe space. We don't think about politics as much. And we really enjoy learning and talking about the universe.

• 1:25:17Brian Keating?

  And what could be more delightful than doing that? So, thanks again. It's been, it was a fun time, it was a good end of the year. Maybe I'll do one more of these live streams, a couple more of these live streams if you guys like them. And otherwise, yeah, please do share wherever you're listening to this. Leave a rating and review. This will be on audio podcast platforms. We're coming up on a thousand reviews of the podcast on Spotify and on Apple. Kind of want to hit that thousand number before the end of the year. So that's your only, you know, I only ask you to give me free gifts. I'm not asking for anything of, of that costs anything. Maybe I do need some merch, maybe a Keating brand telescope or a Keating, you know, crafted meteorite ring or pendant or some amulet or something like that. Let me know what you think of those crazy ideas.

• 1:26:02Brian Keating?

  Don't forget to subscribe to not only the channel, but the mailing list. Hopefully you can get, God, I never get this right. There it is.

• 1:26:11Brian Keating?

  To the mailing list as well. It's not really cool stuff every month, every week, actually, every Monday. So enjoy that. Enjoy your day if you're in the US. Happy Thanksgiving. I'm really grateful and thankful to all of you. I have a great episode coming up with Kelsey Johnson. I've been, had that recorded, did not get around to releasing it yet, but hopefully it'll be released before the weekend. So you'll enjoy that. Another renowned astronomer, and you're gonna love her book and her conversation with me about the biggest picture concepts in philosophy, science, even again, theology. I'm not afraid to talk about it. I don't proselytize, but I do think it's part of the human condition. We only get so much time here on this earth. Gotta appreciate it, take advantage of it, and enjoy it.

• 1:26:55Brian Keating?

  And what better way than by joining this community of minds? I call the multiverse of minds and the cosmos of brains. Anyway, that's it for today. Hope you enjoyed it. Leave a comment, let me know what you thought. Bye.