Planetary Radio: Space Exploration, Astronomy and Science - A Conversation with Kyoto Prize Recipient James Gunn

Episode Date: April 28, 2021

There is no Nobel prize for astronomy, so the Kyoto Prize for Astronomy and Astrophysics may be the highest international recognition an astronomer can receive. Princeton University professor of astronomy Jim Gunn is the most recent recipient. Jim recently joined Mat Kaplan for a deep conversation about the wonder and beauty of deep space, about the Sloan Digital Sky Survey that Jim co-created and led, and much more. Is there an asteroid with Mat Kaplan’s name on it? That question is at the heart of the new space trivia contest from Bruce Betts.  Discover more at https://www.planetary.org/planetary-radio/james-gunn-sdssSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

A memorable conversation with Kyoto Prize recipient James Gunn, this week on Planetary Radio. Welcome. I'm Matt Kaplan of the Planetary Society, with more of the human adventure across our solar system and beyond. The Sloan Digital Sky Survey opened up the universe as never before. own digital sky survey opened up the universe as never before. Jim Gunn helped conceive and create it and then led the international effort for many years. But that's far from all he has accomplished. He and a colleague also led development of the wide field and planetary camera that helped enable the Hubble Space Telescope to take us so much farther across the cosmos. Hubble Space Telescope to take us so much farther across the cosmos. Jim richly deserved the Inamori Foundation's Kyoto Prize for Astronomy and Astrophysics, which may be the closest thing to a Nobel Prize for Astronomy. A colleague called him the happiest person she'd ever met.

I think you'll enjoy my wonderful in-depth conversation with him today. wonderful in-depth conversation with him today. Asteroid Kaplan? Say it ain't so. Bruce Betts will not reveal all when he joins us for What's Up, but he'll have lots of other great revelations to share. The biannual Planetary Defense Conference is underway, and I've got an invitation for you. The Planetary Society will host the PDC's only public event on Thursday, April 28th at 8 a.m. Pacific, 11 a.m. Eastern, and 3 p.m. UTC. We're calling it Earthlings vs. Asteroids. What's the score? I'll be joined by six international experts on how humanity is working to save our planet from the fate of the dinosaurs. It's free, and I hope you'll join us. You'll be able to watch at planetary.org slash live

on the Planetary Society's Facebook page or on our YouTube channel. The recording will be available on demand right after the live show. A quick look at the downlink begins with the ongoing triumph of ingenuity, the Mars helicopter. The little flying machine has completed three perfect ascents as I prepare this week's show. Ingenuity project manager Mimi Ong will return as my guest in May. Bill Nelson is a couple of steps closer to becoming the next NASA administrator. The former senator got a friendly reception in his Senate hearing.

And Russia has announced that it may end its involvement with the International Space Station. Roscosmos Chief Dmitry Rogozin says development of an independent station is underway. Russia's also working with China toward human lunar exploration and establishment of a lunar base. You can catch our weekly newsletter every Friday at planetary.org. As a young man, James Gunn worked with and for many of the greatest astronomers of the 20th century. You'll hear him mention some of these mentors and colleagues in our terrific conversation. Jim would eventually help develop the digital detectors that have advanced astronomy far beyond the days of photographic plates. That advance would also enable the Sloan Digital Sky Survey that Jim headed for so long. It will be much more interesting to hear these stories

from the man himself. You won't wonder why the Inamori Foundation chose to award Jim the Kyoto Prize. Jim Gunn, congratulations on the award of the Kyoto Prize. Quite an honor. And it is quite an honor to talk to you as well. Thank you so much for joining us on Planetary Radio. It's always fun to do these things, Matt. And I like very much to reach out to people and tell them a little bit about what I do and why I do it. So thank you. That's apparent from what I've already learned about you and from watching your Kyoto Prize lecture, which we will provide a link to from this week's show page at planetary.org slash radio.

And I encourage everybody to go and take a listen because it's a wonderful, warm, and fascinating conversation. I have so many questions for you, beginning with sky surveys. I mean, really, this is a great human tradition, isn't it? I mean, astronomers, whole civilizations have been charting the skies for about as long as we've been human, right? Oh, yes, absolutely right. And, you know, in the beginning, I suppose they were used to keep track of seasons and crops and such things. And then they evolved basically into navigational tools. And of course, it wasn't really until, oh, I think the late 18th century that people began to wonder about. I'm sure people had wondered before about what the stars were and what was going on.

But they began to have a little bit of physical and actually 19th century is what I meant. Because once photography came along, it became obvious that there were many, many more stars than we could see. It became obvious that there were many, many more stars than we could see. They were grouped in funny groups and clusters and people wondered about what they were and where they were. And that, of course, was the cause of an enormous records of essentially all the sky because they were being used to look at how stars move, how stars change. Didn't have very much idea what stars really were then. But it became clear, I think, quite early that astronomy was basically a statistical thing. There were lots and lots of very, very different things, but they fell into classes. And if you are going to understand them, you better understand something about the statistics. And now, of course, astronomy is an almost entirely statistical subject.

You worry about the large-scale structure of galaxies in space. It's all very, very complicated statistics. And we wouldn't know anything about this without surveys. I mean, you can study individual objects to death, and you don't learn anything about the populations. You don't learn anything about how they evolved. You don't learn anything about how they were formed. So I think surveys are more and more a kind of backbone of astronomy. I don't know if you know Linda Schweitzer, astronomer and author. Yes. No, I worked with her on her book, actually.

I worked with her. I provided material for her book. It's a wonderful book. I really quite like it. Actually, I should have put that question another way because she acknowledges you in that book, which we talked about not long ago on this show, Cosmic Odyssey, about those decades of great astronomy performed by and at the Palomar Observatory, which, of course, was where this wonderful Palomar Observatory sky survey was done. And you talked about that a little bit in your lecture. I mean, you're talking about photographing

the stars, but not taking the next step. I mean, what was the place of that survey? Oh, that survey was immensely valuable. I think mostly because of things going on in astronomy that were entirely peripheral to the photographic process, right? Because the survey came along, it really became available in about 1950, I don't remember the exact year, at almost the same time that X-ray astronomy was getting going, that radio astronomy was getting going, that photoelectric measurements of brightnesses and colors of things in the sky were getting going, we had not very much idea about what was out there. And the Palomar survey was of limited use for making precise measurements of things, except positions. It was quite good at measuring positions. And it was just immensely valuable because you could see it. There was a strong radio source.

You would work very hard to figure out where it was in the sky. And maybe you could see it on the Palomar sky survey and learn something about what it was you know whether it was a galaxy whether it was some peculiar cluster whether it was this that or the other and so it was the sort of primary survey tool for astronomers for a very very long time but it was clear that there were serious weaknesses because it was very very difficult to make precision measurements of colors or brightnesses from it and so people talked about better ways to do things with electronic detectors that actually made quantitative measurements but it was a long time before that technology evolved to a place where we could actually do it.

We are going to come to that, of course, because you were the driving force behind that effort when the time came. But I can't leave Palomar yet, because like Linda, you talked in your lecture about this wonderful character, Fritz Zwicky, who was largely behind that Palomar survey. Those Schmidt instruments, I have a Schmidt telescope sitting downstairs on a tripod. And I wonder if you could just say something about what a character he was. Did you know Fritz Zwicky, by the way? No, I knew him quite well, actually. And there are various stories and anecdotes.

There was a recent biography, which I can't remember who wrote it, which captures him, I think, extremely well. He was just incredibly eccentric. You didn't want to cross him. He didn't suffer fools lightly, and he thought almost everybody else in the world was a fool. I got on with him actually very well, partly accidentally. There was an edict which came down in the department at Caltech that retired professors could not have access to the 200-inch telescope. This was aimed entirely at Fritz. Gosh. What a way to run science. Okay. I was a wet-behind-the-ears young astronomer,

and Fritz had various things that he wanted observed, and so he would come to me and I would observe them for him. So we got along really, really quite well. Fritz had various things that he wanted observed, and so he would come to me and I would observe them for him. So we got along really, really quite well. You should tell your listeners that they need to go and read about this man because he was really one of a kind. He was interested in jet propulsion. He invented JATO. Do you remember?

Oh, yes. Jet Assisted Takeoff. Fritz invented that. I'll be darned. During the war while he was working on things. So he was really a universal man. He was interested in engineering. He was interested in... He broke his leg once because he loved to ski, and he was trying to invent a new way to do very fast turns coming down a hill very quickly on skis and spirally fractured one leg. Oh, God. So, you know, he was just a character and a wonderful, wonderful character as long as you were not on his bread list. So I'm glad to hear that you weren't put on his spherical bastard list as he described so many people. No, I don't think I was a spherical bastard. We should explain.

This came up in my conversation with Linda as well, that he said most astronomers were spherical bastards because? Linda as well, that he said most astronomers were spherical bastards because... Well, basically because they look the same from any angle, but I don't remember that. I think that's it. I think that's it. We'll move on. You know, the way you describe Fritz Wicke, because he was into so many things, could do anything. Your colleague, Alison Coyle at UC San Diego, who just provided the introduction to your Kyoto Prize lecture in the Kyoto Prize Symposium that UC San Diego held just a few weeks ago, says that you are that rare combination, a theorist, an experimentalist, and a builder of instruments. Do you agree with her? environmentalist and a builder of instruments. Do you agree with her? You know, it has been said many times, so I have been very lucky in my career. When I was a child,

my father, who was a geophysicist and wandered around the country, had a portable machine shop, which he needed in order to keep his instruments going. And especially during the war, you couldn't find parts. And so I learned very early to be very interested in building things. And that has stayed with me. I think it's actually my passion, even more than science. And so, you know, things like the Palomar instruments and Sloan, I was really building instruments so that other people could do science. And I love to do that. And people have asked me, you know, well, doesn't it make you sad that you didn't do more science?

But I built all these cool toys. That's great. I saw the telescope that I guess you started with your father, which later you actually used and got your first paper published. Yes, yes, that's right, that's right. Actually, I built that after he died, but we was, we had built several things together before then. What started your interest in the sky since you were already mechanically inclined? That's a good question. I think I talked about, I wrote an autobiography for annual reviews recently.

annual reviews recently. I don't think I talked about this in my Kyoto lecture. My dad was a geophysicist, and one of the books that I really liked when I was a kid was his astronomy text. For the life of me, I cannot remember who wrote the book. I will eventually perhaps discover this before I leave this mortal coil. But the subject was, of course, not very well developed. And he had been a college student in the 1920s. And, of course, there was a lot going on in astronomy. But this book was mostly just descriptive, lots of pictures of planets and galaxies the galaxies fascinated me and there was a children's book called the stars for sam which i'm happy to say is still still excellent and has been updated and things and so it just caught my fancy enormously

and because he liked to build things we talked about it and we started building little telescopes and so you know i began my amateur astronomy career at the age of 10 or 9 or 10 or something like that and it just really never and maybe i wasn't clever enough to original enough to think about something else to do because the thing you know that really that really caught my heart so that's and I just stuck with it well that's good for the rest of us I have to say it worked out pretty well I'm glad you weren't distracted by too much you got to Caltech as a grad student, what, in the early 50s, thereabouts? Let me think. I graduated, I did physics and mathematics at Rice, and I think I graduated in 60. Oh, yeah, I'm too early. That's right. Then I got my degree in Caltech, I think, in 65 of that order.

65, 66, yeah. What was the state of cosmology as you got to Caltech, where you thought you were going to work on general relativity, but didn't get the chance? And unfortunately, H.P. Robertson died the summer before I arrived, and he was the only relativist on campus. But I was very lucky. Since I had earlier been a very active amateur and had done astrophotography and built telescopes that tracked and things like this, I sort of got a head start on my colleagues because I knew about telescopes. And so Bob Kraft, who was an astronomer at the Mount Wilson Observatory, and at that time, that family was very closely knit. And so I started working almost right away on a project with him to do stellar spectroscopy. But I was also very

interested in cosmology. And so I sort of kept up. I learned things on my own. There was a general relativity course taught by a wonderful man from JPL called Frank Estabrook. And so I sort of I was able to learn about the things that I that I wanted to learn about. to learn about. And when it came time to do a thesis, I was also quite interested in statistics and surveys and things already then. And so I did a thesis on the statistical structure of galaxies in space, sort of, I think, one of Jim Peebles and I started this subject, but he got there first. So that's just the way it was. But cosmology was not in a good state. I mean, we didn't know about dark matter. We didn't know within a factor of two or maybe more how old the universe was and what the Hubble constant was and all of these things that we now know, you know, to the order of a percent. to the order of a percent. At that time, I could not imagine that we would progress to the extent that we have. But we didn't know about dark energy, right? Oh, no, we certainly didn't know about dark energy.

We didn't even know about dark matter, right? That kind of slowly developed. And the subject at the time was very strange. And the contrast with the subject today is just incredibly marked. The subject then was the province of a few powerful men who had access to the world's biggest telescopes, Alan Sandage, Gerard de Bocaleur. And it was very difficult to know whether any of those characters was correct or not. They published a lot, but there was no way to find out whether a particular thing that they claimed was right or not, because they were the only people who had access to the tools to do the experiment.

The whole idea of science as being something, you know, you do an experiment, somebody else does the same experiment, they get the same answer, and you have some idea about whether it's right or not. Those checks and balances simply didn't exist. I saw a great quote from you. whether it's right or not. Those checks and balances simply didn't exist at the time. I saw a great quote from you. Cosmology may look like a science, but it isn't a science. A basic tenet of science is that you can do repeatable experiments,

and you can't do that in cosmology, said Jim Gunn. Yes, yes, yes. Well, that's just the whole picture of the universe. What we can do is take the science we learn in the lab and locally in the solar system, because we can do some exploration, and try to generalize it, to expand it to the whole universe. We can be lucky sometimes, and we can be unlucky sometimes. we can be unlucky sometimes. But proof is something that's very, very hard to come by in astronomy. You can make theories that fit the observations. But for elaborate science, you can repeat the experiment. But there's only one experiment here. There is just the universe.

And so you don't know whether you're being lucky that your theory fits the things you know today, or whether it's just a fluke, right? The fact that we are making such detailed models now that seem to fit what we see, I think is saying that cosmology is becoming, it's becoming more and more of a science. It was not a science when I started this thing. They were just a million crazy ideas, right? There are still crazy ideas that come out of the woodwork. But my faith in the subject has increased a lot just because of what we understand, the precision with which we understand it. And we can kind of predict what's going to happen next.

I mean, the Event Horizon Telescope, for example, right? That black hole looks like we thought it should have. So that's, I think, pretty amazing. How do you get to one before? So that's, I think, pretty amazing. The most amazing thing to me, actually, is that when Jim Peebles wrote down, who I think, incidentally, is the greatest astronomer of this century, he's a cosmologist of the century, and he wasn't really an observational astronomer, but certainly the greatest cosmologist. He had been fascinated from the beginning, from its discovery in whatever it was,

67 or so, of the cosmic microwave background, how it arose from the Big Bang, the structure that one should see in it. When he first proposed the cold dark matter paradigm, which is essentially the way we believe the universe is today, except that he didn't know about dark energy. He predicted these acoustic modes that came from the universe very, very early. And by God, they were there. And it's just amazing. I hear the emotion in your voice. Yeah. Because of the profound, what, beauty of this?

Well, the beauty and correctness. I mean, it says that we understand basically what went on in the early universe. That's completely remote from the physics of our understanding. But Jim put it all together and predicted essentially exactly what we see. So it's amazing. It's wonderful to hear that you can still be so overwhelmed by a discovery like this, that we mere humans are capable of this kind of work. We're capable of doing these things. That's right. That's right.

We're the Planetary Society. We tend to talk about small, round, hard, cold things. But we do get to talk on this show anyway, now and then, about those largest of structures in our universe, galactic clusters. I can tell this is still a lifelong fascination for you, right? Oh, yes, yes, yes, it is. I sort of got into, you know, exoplanets and things were discovered late in my career, and I never, I'm fascinated by the subject, but I never worked in it. It's certainly a sort of, it's a major tenet of astronomy these days. And I sort of regret that I didn't,

but I was pretty old actually when they came along. Oh, and yet the Sloan survey, as we will talk about in a few minutes, has contributed at that level. So I think the S stuff is just wonderful from Sloan. And it was nothing that we intended to do, right? Well, we'll come back to that. We also, much more regularly on this show, we talk about spectra.

We talk about spectroscopy all the time. Not long ago on the show, it was talking about the spectra of rocks on Mars that have been zapped by lasers. of rocks on Mars that have been zapped by lasers. Your use of spectroscopy has been on a somewhat larger scale than individual rocks. But Sloan looked at rocks, too. You know, but nevertheless. But it was a key point, right, in the upgrade that because of this progress that was needed following the Palomar Observatory survey,

that did a wonderful job. But you, you knew, and you and others knew that we needed to build on that, particularly through spectroscopy. Right, right. Well,

and also photometry. I mean, the, you know, you could do photometry of photographs, but there were only two colors, and so it was very limited, and the accuracy was very limited just because of the photographic process. So what we needed was something that was

very much more quantitative. I don't know, we'll probably talk about this later, but at some point it occurred to me early on that the same telescope that was doing the imaging, which was the thing that I thought of first, and it just then came to me that that very telescope would also be an incredibly useful spectroscopic instrument. So that's basically where the idea of Sloan came from. We had to wait for technology to catch up with the need to learn these things. I'm thinking of the way you and I are looking at each other right now.

CCDs, charge coupled devices. How did you realize that here was a device that might enable the kind of work that you were hoping to do? Well, I think it was pretty obvious from the beginning. Jim Westfall, who was a friend and probably the most important mentor in my career, he was actually a planetary scientist, were very interested in working on detectors. And so we worked on viticons and various things. Somewhere in the middle of this detector work that was going on in 70s, RCA made a tube called a silicon viticon, which had a silicon target, you know, very much like a CCD. The photon comes in, makes a pair. The pair, the electron deposits on the back and you use an electron beam to read it. So it was a sensitive viticon, but the read noise was very, very large.

he was a planetary scientist. And I worked very hard for a while trying to figure out how to take exposures long enough that there was enough signal that you could read them reasonably well, but that came to nothing. A couple of years after the silicon viticon came along, I think it was RCA first, but the real work was done at Tektronix. No, at- Bell Labs? Well, Bell Labs invented the device. Bell Labs invented the CCD. And I think that was during the time that the whole telephone industry was being taken apart by the government because of antitrust things. They never really got into the commercial business of building these things. But RCA started making them for commercial purposes. And Texas Instruments started making them

for scientific and military purposes. NASA was putting a lot of money into the effort at Texas Instruments. They built the first really good detectors, and they went on the Voyager mission. There were lots of places where they went. But since JPL was sort of, you know, right there, and Westfall had been working with them a lot on the silicon viticons, we sort of had an inside track to this development. And, of course, JPL were very interested in people using these things so that they could find out how they worked, because they could test them in the lab, but they couldn't test them in the sky in any reasonable way.

So Jim Westphal and I started working with them and built a couple of cameras using 500 by 500 thin devices. The thinning is very important. And built a camera for Palomar called FUI, which was Prime Focus Universal Extragalactic Instrument. I love it. The combination camera and spectrograph which i they're called parallel beam boxes these days and they're very common but i think that was the first one

and then we got word that a project that was just called space telescope at the time that's now Hubble was in trouble. They were going to use a camera built around one of these big viticons. It wasn't a silicon viticon, but it worked sort of the same way. It was called a secondary electron conduction viticon. And the target in this viticon was potassium chloride, very thin salt window. And it was incredibly fragile. The thought of this thing withstanding launch loads and things like that, just absurd. And it was being done at Princeton, sort of under the aegis of Lyman Spitzer, who had been a major mover, of course, in the project. But NASA really got, they just knew it wasn't going to work. They didn't exactly take the project away from Princeton, but they said, you know, we need a plan B.

And so they put out a proposal for this. And Westfall and I had been working with CCDs enough to know that that's the way you've got to fly. That's the only thing you can do. So we put in a successful proposal for the Wide Field Planetary Camera and the rest, as they say, is sort of history. So we worked a lot with Texas Instruments on CCDs, learned how they worked, did a lot of good astronomy, I think. And we got money from NASA for the same reason, to put these things on the sky.

We built FUI first, which was this single CCD instrument. And then we built a quite massive instrument called Foreshooter that used four CCDs with the same kind of image splitter that was going to be used in the Wide Field Planetary Camera on Hubble. And that was going to be used in the Wide Field Planetary camera on Hubble and that was very successful we found very high redshift quasars we did a survey for clusters of galaxies and so you know I had kind of forgotten about the survey business but Martin Schmidt and Don Schneider and I did a high redshift quasar survey John Hessel and other people and I did a high redshift cluster survey. The high redshift quasar survey was spectroscopy. It was done in a slitless mode with this instrument. That's a little hard to explain, but you have a spectrograph, but you don't have a slit, and so it images. And so what you get is little spectra on the sky background.

So you can't work terribly faint, but you can cover an enormous area. And we found the highest redshift quasars known at the time of redshifts around five. And the cluster survey was just done. you take a picture, you move, you take a picture, you move, you take a picture, you move. But we also developed at that time, we didn't develop actually, we utilized a technique called TDI, which means time delay and integrate. And it's a military technology. And time delay and integrate has absolutely nothing to do with what it does. But, you know, one of the beautiful things about a CCD is that the photons come in, they make charge, and then you read this device by moving those photons along a row at a time in the detector,

and then the last row you read out to an amplifier. And there could be more than one amplifier, but in those days there was only one. The beautiful thing about this technique is that you never stop. It was developed for reconnaissance on the ground. The satellite or the airplane flies along. There is a CCD which is doing this, and you have to move the charge at exactly the right rate. So the image of a tank or something stays on exactly the same pixel as you move. You do it on the sky, a star stays on the same pixel as you move. Do it on the sky, a star stays on the same pixel as you move. And so for both FUI and Foreshooter, we implemented this technique. And so

basically it makes a tapestry of the sky. So you never waste time stopping, closing the shutter, reading the device. The device is reading the whole time. And so it increases the efficiency of light gathering by a very, very large factor. And we were the first people, seriously, I think, other people had a little bit to use it. Stay with us. Jim Gunn has many more stories to share in a minute. I've got something so cool sitting right next to me. It's a digital frame from Aura, and it is displaying beautiful images of my family. I know what you're thinking. Yeah, I had one of those old digital frames. It may still be in my garage. Aura gets it so right.

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up to $100 off their Wi-Fi digital frames with the code PLANET. Visit oraframes.com to redeem this special offer. That's oraframes.com with the code PLANET. We're back with James Gunn. Before we leave the Hubble Space Telescope, what became the Hubble Space Telescope and your contribution to it, that first wide-field planetary camera for HST, I came across this wonderful term, what some of you, I think, called yourselves. Are you a whiff picker? Yes, yes, yes. Because that's what we built, right?

So much cutting edge technology. I mean, not just CCDs, fiber optics, computer processing. Was it during this period that you realized, okay, now we can take on this giant jump over the Palomar Survey, which would become the Sloan Digital Sky Survey? No, no. It wasn't until considerably later. And that's a story also which I told in this annual reviews article, but I'm just trying to place this in time. Sure. Yes, it was before the launch because the launch wasn't until 1982. I had left Caltech and come

to Princeton and was mostly working on theoretical things, although I was still working at Palomar with Martin Schmidt and Don Schneider on the Quasar survey and with other people at Caltech on the cluster survey. And they were nice enough to even – they wouldn't give Uncle Fritz time on the 200. I had left. They wouldn't give me time. I was doing this work with Caltech colleagues, so that was okay. Anyway, one of those trips to California, I walked into my friend Jim Westfall's office, and we were talking about the Wide Wheel Planetary camera because that's what we were doing. and Morley Blauk, who was the chief engineer, CCD engineer at Texas Instruments, completely unannounced, knocks on the door, comes in and says, oh, Jim, I'm glad you're here.

Both Jims, I want to show you something. So Morley reaches in his briefcase and pulls out a chip carrier that's about this size. In it, there is a single chip with a single CCD, two and a half inches across. And the things we had been doing before were a centimeter across. Now, was this TI or was it Tektronix by this point? This was Tektronix by this point. Because Morley had left TI and had gone to Tektronix. Tektronix wanted to develop big CCDs to make really super fast oscilloscopes. So you could write on this thing with an electron beam and take your time reading it later. You didn't have to read the signals in real time. That apparently never worked out,

but they made a lot of money on them because these CCDs are incredibly sensitive x-ray detectors. Well, they were able to make mammography x-rays that exposed the patient to a tiny, tiny dose compared to the technology, to other photographic technology, basically. And it was the same reason. So quantum efficiency one versus quantum efficiency a thousand. I mean, were you blown away when he showed this to you? Caltech to a meeting at Kitt Peak where they were trying to figure out how they could use a three and a half meter honeycomb mirror. They had been working on this honeycomb technology, Roger Angel's technology. I sat there the

whole time during this meeting trying to figure out how to make these huge CCDs. They were not real yet. Morley said, this thing doesn't work, right? Let's go. That was basically how Sloan was born because I knew I can make a telescope that would do this TDI mosaic scanning of tapestry scanning.

And it wasn't until a little later that I realized these devices, that the match between the photometric instrument, because I was just thinking about imaging the sky, I was going to replace the sky survey with a CCD survey that had much, much, go deeper, that had much, much better photometry and many more colors. And then I don't remember exactly how it happened, and it may not have been even my idea. But anyway, it came to be that I realized that these detectors were also marvelous for spectroscopy. And on a two and a half meter telescope, which turned out to be the sweet spot for the backup a little bit. Princeton had just become involved in Apache Point Observatory in New Mexico.

And it was a good site, but not a great site. It turns out that when you consider the size of the pixels, the read noise, the sky brightness, all of these things, there is a kind of sweet spot for a telescope, for a survey telescope anyway. And that turned out to be a little smaller than I was thinking about originally. Two and a half meters was about right. With a two and a half meter telescope and the kind of spectrographs that I knew you could build, we could reach down to about 18th magnitude. And that's about a million galaxies. Then the various people interested in the project sort of divided into two. There were the people interested in the imaging. There were the people interested in the spectroscopy. But we talked to

one another quite a lot. The beauty of it that we hadn't realized at the beginning was that the weather at Apache Point is okay, but it's not great. So when it's great, you image. And when it's not great, you do spectroscopy. And your efficiency is enormously improved because you can use the telescope. Not all the time, because sometimes it's really socked in, right? But when it's clear, we were always able to work. And that's one of the big reasons why Sloan was so successful. So you had the right location. You now had the right detector, or at least the beginnings of it. You now had the right detector, or at least the beginnings of it.

Right. This was such an ambitious, huge project. I mean, there was a consortium to put together. Yeah, that's right. Well, the consortium had already begun because the Hatchey Point Observatory existed some years before Sloan happened. So the prime mover was University of Chicago and Don York. And there was Princeton, there was University of Washington, there was Washington State. I think that was the partnership at the beginning. A three and a half meter telescope, also using this angel lightweight mirror technology, was already underway. We built

a spectrograph for that telescope sort of in the process of doing Sloan but fortunately we did not have to put this consortium together right from the beginning but it was a big enough project that we needed a lot more partners and so we got Fermilab involved, which was, I think, in the end, not a mixed blessing. I think it was a real blessing, but it was different for various reasons. And so the consortium just began to grow. We had no idea how much this thing was going to cost. Just no idea. Nothing like this had ever been done before. We sort of knew how much the telescope would cost. We knew we were negotiating with Tektronix about the detectors,

and they gave us a quite good deal on the detectors. But the thing that we were very naive about was how much it was going to cost to store and reduce the data, write the software, because it was a huge, huge job that we just didn't really have proper appreciation for. I think the first realistic budget, no, no, that's not the right word, the right word. Sort of semi-thought-out budget that we had was around 20 million, and the project cost 80 in the end. It was really very difficult because during the project, there were several occasions when we did not know that we could pay the next pay. We had money for the next payroll. On the other hand, if we had said up front that this project is going to cost $80 million,

it probably would not have been funded. So... That works out. It works out. It does. Thank goodness, thank God, it was funded, and you began this great work, which resulted in this enormous database, which is still so important today. Can you talk a little bit about how big a jump this was over the earlier Palomar survey? The Palomar survey, various people had tried scanning these plates and there were databases. I don't think of anything like the whole sky, but the accuracy just wasn't there.

Data were taken, they were stored, they were reduced. It wasn't anything like this big, but we can't claim that, you know, that we went there first. And that was the infrared astronomy satellite, right? That did this work from orbit, obviously. Right, right. Because, you know, you couldn't store a bunch of photographic prints in your room from that because they didn't exist. Yeah. So it was a really enormous step. I don't know a factor, but I think it was at least 100 times bigger than any other

astronomical database. One thing that we learned very early, I was project scientist in this thing the whole time that it was going on. And I was pretty intransigent about doing the very best job we could do, which not all of our colleagues agreed with because they were interested in saving money. And sometimes doing things, it's my opinion that you always win by doing things right. if you do things not right it just costs you more later because you realize that the data is and and my my Princeton colleagues were very very much with me and so the the thing that we tried to to realize was that in the software the data are their photons and so there are a finite number of photons and so there is finite accuracy that can be achieved and that was the accuracy we wanted to achieve to the photon to the phone and I

don't know that we succeeded 200% but we did a pretty damn good job you know and that has just enabled so much as time has gone on the the asteroid stuff all of the galaxy morphology stuff the galaxy spectra nobody really believed we could do the spectroscopic job that we did with a telescope this size because other spectrographs were not so efficient. So we worked very, very hard on getting the photons to the CCD, but also, you know, having software that can extract the information. But it wasn't just software. You had one slide, you spent maybe 10 seconds mentioning this in your Kyoto Prize lecture, but I was just blown away. And I know

that there has been work done like this since then, but you were the pioneers. You mentioned that you made these plates and that holes were drilled in the plates that exactly corresponded to the positions of the galaxies that were being observed in the telescope, and then you had to put fiber optics behind this. What? I mean, how many of those plates did you have to make? How many holes had to be drilled? There were a couple or 3,000 plates, and each one in Sloan had 640 holes.

Oh, my gosh. But let me tell you my favorite story about that. Well, there are several good stories. Early on in the project, the most fun meetings would be when we would get together and try to figure out how to get the fibers in the focal point. Wonderful things, right? Fancy robots and things. We finally decided. We knew that CNC milling machines could place the holes to the accuracy we wanted. These are those computer-driven milling machines.

Very accurate. Yeah. Very accurate. It was tricky because the focal plane is curved. The light doesn't come in exactly perpendicular to the focal plane, so the plate has to be bent at a different angle when you're drilling from an angle in the telescope. Engineers at UW who did this, they were just wonderful, and it's a quite simple mechanism that does this. We knew how much that was going to cost, roughly, and we knew how much that was going to cost roughly. And we knew how much a not particularly well-trained person who would just plug fibers into the holes cost. And the big problem was, what if they plug them into the wrong hole? so somebody had the bright idea that we what you do you have the plate and you have the fibers plugged in you don't care which hole you just plug the fibers in and the fibers go to a slit

and the fibers are arranged along the slit in order one 1 to 600, you shine a laser along the slit and you watch the fiber on the plate. Brilliant. And video. Isn't it brilliant? Yes, yes. You just reverse the flow of the photons. My wife claims to be the one

who has this idea, and I think correct. She's also an astronomer. Good for her. And that solved the I think, correct. She's also an astronomer. Good for her. You know, and that solved the problem. Fascinating. The other really cool thing was that we got the imager going first, and it was going for a few months first. And we drilled the very first plate, which was a bunch of reasonably bright galaxies in the coma cluster. And we put the plate on the telescope and we got 640 spectra, the very first plate.

Wow. And that was amazing. God, it's like landing on the moon or Mars. But pretty cool. Yeah, very cool. How do you measure your success? I mean, how much of the sky was eventually imaged? How many objects did you get images of or spectra of?

I should know those numbers more accurately than I do. We got the whole northern sky above 30 degrees galactic latitude. We got a big chunk of the southern sky. We basically got all the sky that could be reached with reasonable quality from the site, except for the galactic plane. And we simply could not cope with the data. galactic plane, and we simply could not cope with the data. Later in Sloan 2, there was a project called Segway that did go into the plane, and we had some success with that, but the software is just incredibly complicated. There's 40,000 degrees in the sky. I think we, in the end, did something like 20,000 degrees. The original survey, which has now been surpassed

with later embodiments, did a few more than a million galaxy redshifts, and about 120,000 quasar redshifts. The way this worked was that we took the images first, did the astrometry on the images, so we knew where to drill the holes in the plates. For galaxies, you could see that it was a galaxy. For quasars, it was a little trickier

because we had to depend on colors to be different enough from a star. Basically, we took spectra of almost everything we could whose colors did not look like stars. Most of those were quasars. So that's basically how it worked. We did the imaging first, we reduced the imaging, then went after the spectroscopy. But short of those that you got spectra from, weren't there hundreds of millions of objects? I mean, the spectrographs were only powerful enough to go down to about 18th magnitude, and the imaging went down to 20 seconds. So there were about

a billion objects that we got spectrometry for. Is there anything much more beautiful in nature than galaxies? Oh, I think all of nature is extremely beautiful. Good answer. Galax galaxies are very beautiful. Where I'm going kind of is that I've seen, in fact, in your lecture, you took a piece of sky and zoomed in on it and zoomed and zoomed and zoomed until we saw these beautiful individual objects. The hundreds of billions of our hundred billion or so of them across the sky. And it's just, I mean, you can see it in the, you know, those deep sky fields taken by the Hubble Space Telescope as well. It just blows you away.

Yep. Yep. Now, we have a big mosaic on our wall from the Hyper Supreme Cam. We're somewhat involved in that, the big Japanese camera on Subaru. And it's mind-boggling, you know, and you get close and we're almost at the confusion limit. The galaxies are overlapping. Almost at the confusion limit. The galaxies are overlapping. Those objects that you weren't looking for,

thousands of asteroids discovered by Sloan. But I'm also thinking of those little stars that people pretty much knew existed, I guess. But you know what I'm talking about, the brown dwarfs. Brown dwarfs, that's right, that's right. The amazing thing there was that people had been thinking, they knew that the atmospheres of these stars, that the spectra of these stars would be dominated by methane. And we knew what the methane spectrum looked like.

They're very cool stars. And so people thought, well, you know, you find them in the infrared. But the infrared part of the spectrum is basically wiped out by the methane absorption. So it's much easier to find them in the far red and the visible than it is to find them in the infrared, and that's why we're so successful. Those asteroids, I need to bring those up again

because I'm with the Planetary Society, and we care a lot about asteroids. We're still finding them. Did Sloan help us to understand how many of these rocks there are? I think so. And, you know, that was a very controversial subject. Jelko Ivisic, who was a postdoc here working on that subject, he had not come here particularly interested in asteroids, but was fascinated, you know, as soon as they started showing up. And they were just a nuisance

to begin with, because they had very funny colors, because they were moving. And, you know, we were trying to find quasars and taking, trying to take, and of course, you go back to an asteroid and take a spectrum, and that ain't fair because it's going from there, right? There were two controversies going on. One, it was known that there were several orbital families of asteroids, which I don't think we understand at all yet, you know, exactly how the asteroids came to be. But there were several orbital families.

And there was a little bit of data on photometry, but not a lot. And so as soon as the Sloan, as soon as we discovered hundreds of them, we very quickly discovered that these orbital families also were chemically different. Just from the colors. That was, I think, probably the major thing. But the other thing that really upset the colors. That was, I think, probably the major thing. But the other thing that really upset the community, and we were sort of interlopers in this community doing asteroids, we discovered that there were very many fewer asteroids in the inner part of the solar system than had been thought before. That has immediate impact on a lot of people's research because of Earth crossers. There were many fewer crossers.

I was going to say, no pun intended, impact. Yeah. Precisely. So, you know, people wanted to prove us wrong because they were getting money from NASA to work on Earth crossers and so on. But that's, yeah. Still plenty of them out there for us to worry about, but also fascinating.

And an unintended result. I'm thinking of other impacts that Sloan had beyond the data that you collected that are still with us today just in how science, big science is conducted, big astronomy is conducted. I think that's a very important question and one that I like very much to talk about. Please. When we started astronomy, in particular physics, less so because physics had these huge experiments with hundreds of people on. But in astronomy, most papers had one author.

Some fair fraction had two or three. People working on NASA projects, there were lots of authors because NASA was doing these surveys. But for ground-based astronomy, it was very much a sort of one or a few person subject. And as I said, you know, the field had been dominated for a long, long time by great men. Men. The thing that Sloan changed and which I am actually as proud of as I am of the science is that we really opened up things. The data, we had a small proprietary period to make sure that it was okay. But even within the collaboration, people would get together with various talents, with various specialties, because it was required

to make this work. And so there were large groups, papers already with large groups of people on them, including, and this is an important thing, including the people who built things. Mount Wilson, somebody built that telescope. Somebody built that spectrograph, but their name wasn't on the paper. It was just the people who got the data and who thought about it. We said at the beginning, this is not a good idea. This is not fair. We said at the beginning, this is not a good idea. This is not fair. This is not putting the credit and the blame.

Something doesn't work. Anyway, and we were quite successful at that. And I think it's become a kind of general thing. But then, of course, when the data become public, everybody can work on it. One of the other things that we did that I'm very proud of, other projects and NASA projects even as well, the people who were involved in the project could carve out a thief. And that was their stuff. Right. And we said from the beginning in Sloan, we're not going to do this. Anybody can do anything they want to, right, wrong, whatever. We reviewed the papers, but there was no formal censorship. We would point out that there were all sorts of errors, and we would point out the errors. And it has just worked incredibly well and made the subject so very much richer

than it was before. I think of this as sort of a democratization of science and scientific data. That's a very good, yes, right, right, right. And even beyond sharing with other researchers, I know that you are a fan of citizen science projects, and I'm thinking specifically of Galaxy Zoo. Galaxy Zoo, yes, yes. And it's been, I think, quite incredibly useful. And, of course, it raises the awareness of science and the way science is done in the public, which I think is enormously important. So, yeah, that wasn't my idea. The Galaxy Z wasn't, but I'm very proud that it happened and was part of Sloan.

This was toward the end of your Kyoto lecture. You wanted to give credit because you were being recognized with this prize, well-deserved in my opinion. You wanted to give credit to the many members of the team, some of whom you've mentioned, but you singled out the younger members and the delight that you got from having young people as part of a project like Sloan. Yes, yes, yes. No, that's certainly true. And it comes back to this question about science versus versus building things project things software things like this it became apparent to me quite early this was probably you know pretty close to the end of my

scientific career because it the project was taking so much time that i couldn't do it and then i had to think about you know did, did this matter? And then I came to the conclusion that it didn't matter. The important thing is that the science get done. So let's open this up. It was already pretty clear that we had to open things up. And it was just so wonderful to see young people come along, postdocs and graduate students. You know, the highest redshift quasar for a long time in Sloan was found by a graduate student in Joey Fun. And you say the highest redshift, therefore the farthest back in the history of the universe. And then the farthest away in space. Yes. Right.

And then the farthest away in space. Yes. Right. It's just so rewarding to see young people come along and grab this stuff and run and see all of this wonderful science get done. And I don't really miss not being in the in the thick of that at all. Far prouder to have done what I've done. Right. What are you most excited about, about what's to come? I mean, here we have a whole new generation of giant ground-based telescopes now being built. First light, not far off, but also these new space telescopes. Maybe finally James Webb Space Telescope launching later this year. But what I'm really thinking of, with you in mind, is the Nancy Grace Roman, formerly known as the Wide Field Infrared Space Telescope, or Survey Telescope, WFIRST. Do these excite you? Yes. James Webb excites me quite a lot, because to find out what's going on early in the universe at very high redshift, you have to look farther and farther into the infrared. It doesn't have very much survey capability. The field is too small, but it will certainly tell us a lot

about the way galaxies form and how they evolve early. You know, lots and lots of papers are written about this from ground-based data, but there's always an enormous amount of speculation and extrapolation to do because we just don't have the data and Webb will give it to us. I am somewhat less excited by, and I'm sorry to be saying this because many of my colleagues at Princeton are very involved in LSST or the Nancy Roman Telescope. I think when you're looking very far away and trying to figure out what's wrong, trying to figure out what's wrong, that was a Freudian slip. Trying to figure out what's going on.

It isn't necessary to look at the whole sky because you get such an enormous volume going deep. And so we've been involved for a while in this hyperspring camera on Subaru with the Japanese. And I'm not entirely sure that the Roman telescope is going to tell us very much more than we know from this. The depth is comparable. They certainly cover a lot more sky, but we're so far from, I mean, we're pretty far from exhausting Sloan, and we're just infinitely far from exhausting HSC. I'm a little worried that there's going to be so much data that people get drowned. I don't know. And I'm not sure that it's going to be so unique. Now, that's unfair because one thing that looking at the whole sky does for you is enable you to discover extremely rare objects.

But as far as the statistics of galaxies and the origin of galaxies and all of these things, I'm really not sure that it's going to tell us very much that we won't find out in other ways. I could well be terribly wrong, but that's what I think. You know, right up front, I mentioned your colleague at UCSD, Alison Coyle, who talked about you being sort of a master of many trades. But she also said that when she was at Princeton and she was in the astronomy department in the astronomy building there, she used to see this guy, bearded guy, usually in the basement.

And he seemed so happy. He was whistling all the time. And she thought, oh, he's a technician. He's building instruments. Turned out it was you. But she said you seemed to be the happiest person that she had ever seen. Well, that was when we were building the Sloan camera. And I was pretty happy.

You still sound like a pretty happy guy. Yeah, yeah, yeah, I am. And I really love doing what I'm doing. I mean, this physical business is sort of getting to me. I'm very weak, but it's improving. So, you know, we'll see what happens. I'm glad, Jim. And I sure thank you for what has proven to be a wonderful conversation.

I really have enjoyed this. I hope you have, too. Well, I've enjoyed it and always do, but this was very, very nice, Matt. Thank you. And I hope that both of us get to find out whether the Roman telescope, WFIRST, whether it maybe surpasses your expectations. But generally that happens, right? There are a few instruments which kind of fall on their faces, but generally, if they're well done, and I think both of those are very, very well done, they end up surprising you

in the end. Certainly, Sloan, it just did so enormously more than any of us thought it would. Regardless of the success of any new single instrument, I bet you would agree that there's a heck of a lot of great science ahead of us, some of which we don't even suspect. Oh, yeah, most of which we don't even suspect, I think. Yes, yes, right, right, Matt, absolutely. Thank you, Jim.

Thank you, Matt. It was really, really lovely. Thanks. Bye-bye. Jim Gunn is Emeritus Eugene Higgins Professor of Astrophysical Sciences at Princeton University. He is also the most recent recipient of the Kyoto Prize for Astronomy and Astrophysics. As another astronomer who spent time at Palomar Observatory, Bruce Betts is moments away from joining me for What's Up. Time again for What's Up on Planetary Radio. Here is the chief scientist of the Planetary Society. We're going to talk about stuff that flies later on today, but I guess you could say the stuff that is up there in the night sky for us to look up is flying, right? Sure. We'll talk about flying planets today and flying meteors. They'll fly until they burn up. Let's go ahead and start with the meteor shower. Peaking on May 6th and 7th are the Eta Aquarids, and they're an above average shower, maybe 60 meteors per hour at its peak from a very dark site.

per hour at its peak from a very dark site. You're going to want to be in the southern hemisphere for this one. You can see it from much of the northern hemisphere, but not as many, not as well. It's produced by dust particles left behind by our friend comet Halley. So that's a peak on May 6th and 7th. We also got planets you can see from all over the place. In the evening sky, Mars still dimming, but still looking like a fairly bright reddish star, still hanging out in the southwest in the early evening, near reddish stars. Well, kind of near reddish stars. Aldebaran and Taurus and Betelgeuse and Orion, making for the red triangle. And in the predawn sky, we've got super bright Jupiter hanging out in the east along with Saturn to its upper right, Saturn looking yellowish. They'll be around with us for

many months in the pre-dawn and then moving to the middle of the night and then in the early evening and several months from now. Something to look forward to. Speaking of meteors, big rocks, big dangerous rocks sometimes in the sky, Planetary Defense Conference, you're participating as we speak. Well, near when we speak, right? It's happening this week. It is indeed happening this week. A virtual conference hosted by the United Nations in Vienna, people all over the world, tuning in experts in all aspects of defending the Earth from asteroid impact. So I mentioned up front that the public event that is part of the Planetary Defense Conference

being brought to you, about to be produced by the Planetary Society, you can catch it at planetary.org slash live or on our Facebook page. Just look for the video link there. You're going to be one of my panelists, quite a distinguished group of panelists, a big group too. I thought it was just me. No, I'm sorry.

You're going to have company. But they're all people you like, I think. Yes, they are. And they all are experts in this field. I'm looking forward to it. Anyway, that's it. 8 a.m., bright and early Pacific time anyway. 8 a.m. tomorrow, 11 a.m. Eastern Daylight Time.

And I believe, gosh, I hope I have this right, 3 p.m. or 1500 UTC. Yes, that is correct. Thank you. All right, we move on to this week in space history. we move on to this week in space history and in 1928 future planetary scientist gene shoemaker was born an expert in figuring out that all those pesky craters like meteor crater and craters on the moon were actually from asteroid and comet impacts we have just announced a new round in our grants program named after Gene Shoemaker, the Gene Shoemaker Near-Earth Object Grants Program, which funds astronomers around the world to upgrade their observatories to do planetary defense research. So you can find out more about that

at planetary.org slash neogrants, N-E-O-G-R-A-N-T-S. And I bet you're going to talk about that in our public event tomorrow, which, by the way, I think is called Humans vs. Asteroids, because we're going to talk about the status of planetary defense. What's the score? All right, so we move on to... War! And I'm space back. It's a nice new approach. It's hard coming up with something vaguely new after all this time. As we are recording this, 27 April 2021,

there are six spaceships attached to the International Space Station. I just think that's impressive. You've got two SpaceX Crew Dragon vehicles, Northrop Grumman Cygnus cargo craft, and two Russian Progress resupply ships and a Soyuz cruise ship. Within a few days, we'll be down to four because one of the resupply ships will be packed with trash and sent to burn up in the atmosphere. And the first SpaceX Crew Dragon crews will be headed back. Operational crew will be headed back to Earth. Great RSF. I love to think of that as sort of a parking lot up there. And 11 people inside the station right now, at least for a couple more days. Yeah, it's good stuff. Speaking of good

stuff, I asked you, what was the first successful flight on another planet? So it'll be unpowered, don't count parachutes or heat shields or other things designed primarily to land on the surface. How'd we do, Matt? You're going to love this. We got this answer, and most of them were kidding, from four people. William Malcomus in Pennsylvania, Lauren Privet in Maryland, John Guyton in Australia, Maybe Mel Powell in California said it best. But if BB will accept our moon as a planet for this contest, Al Shepard's golf balls predate what I think is the correct answer by 14 years. Do I win, says Mel? No, says Bruce, he predicts. Survey says no no, no, you do not. For the purpose of one question, we will not be reclassifying the moon as a planet.

All right, here is the answer, hidden away at the end of Gene Lewin's poetic contribution this week. Gene, up in Washington. The ears of Radar O'Reilly perked up the other day, detecting the hum of a chopper lifting from the Martian clay. But back in the 1985, an aerobot took flight, released to an acidic sky at a 50-kilometer height. Vega 1 and 2 released one each through the darkness. They did creep, and since I'm a fan of the Herculoids, I would have named them Gloop and Gleep. I love the twist at the end. I didn't see it coming.

Some cartoon trivia there. Is that correct? Those two balloons? That is correct. With Vega 1 technically being first four days before Vega 2 entered the atmosphere. And they hung out for tens of hours communicating before batteries died, floating around way up in the Venus atmosphere. That's going to make Kevin Leahy in California very happy because, Kevin, you're a first-time winner.

Kevin, you are going to be the first to win a copy of that new pocket atlas of Mars, including an overlay, probably an overlay of the state of California, which is what I got with mine. It's great. I've got it right here. We're going to give away one more, as we'll mention again in a moment or two. Some other interesting stuff. Vlad Bogdanov in British Columbia. Jacques Blamont had a dream of a balloon flying high up in the Venusian atmosphere. Decades of collaboration with the Soviet Union and NASA brought this dream to life.

Jacques Blamont, the great French scientist. Very appropriately, Mark Little in Northern Ireland pointed out that it happened, 1985, was about 202 years after the first balloon carried humans into the air, thanks to the Montgolfier brothers in France. Cool. Ben DeBacke, he knows we love innovative units of measurement and comparison. We haven't heard in a while, so here we go. The tether connecting the balloons to the gondola was 13 meters long,

which is just a little bit less than the length of both our cars, our two daughters, my wife, and me all laid out in a line. Sorry, no picture available. No, but that really helps me visualize it. Of course. Hudson Ansley asks, wonder if they ran into any phosphine? I don't know. I don't think they had things to detect that. Finally, one more bit of verse from our poet laureate, Dave Fairchild in Kansas. The Vega program sent to Venus wasn't just a dream. They were

made of polytetrafluoroethylene floating in an atmosphere of toxic acid rain, measuring the pressure of the wind speed hurricane. Wow, nice pronunciation. Thank you. On hurricane or polytetrafluoroethylene? Show off.

I love saying that. That's fun to say. We're ready for a new one. Who was the asteroid Kaplan named after? No. K-A-P-L-A-N. Who was the asteroid Kaplan named after? Go to planetary.org slash radio contest.

No, no, no, no, no. There can't be because I want one. Everybody knows I want an asteroid named after me. Well, maybe it's named after you, Matt. Maybe this is the greatest surprise ever, or maybe it's just going to be really, really disappointing. We'll find out with the contest in a couple of weeks. It's too far past my birthday, so I have a feeling I'm going to be disappointed. They can still name an asteroid Matthew Kaplan or some such permutation. That'd be okay. That's fine.

I would even let them use my middle name, which I generally avoid mentioning. And what was that again? We'll just move on here. You have until May 5th. That would be Wednesday, May 5th at 8 a.m. Pacific time. To get us the answer to this one, which might be kind of personal, one more time we're going to give the winner the Mars Pocket Atlas from Henrik Hargitay and EuroPlanet, the Central European hub.

It is gorgeous. And, yeah, you might just get that overlay of the region that you happen to live in here on Earth so that you can compare it to places on Mars. All right, everybody, go out there, look up in the night sky and think about Matt's middle name. Thank you and good night. Go ahead. What's your response, Matt? I will provide that middle name if someone, even if it doesn't contain that name, I will provide it if someone names an asteroid after me, preferably the IAU. That's Bruce Betts.

He's the chief scientist of the Planetary Society who joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its members who gaze across the universe, become part of their vision at planetary.org slash join. Mark Hilverde is our associate producer. Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. Ad Astra.