Planetary Radio • Feb 03, 2021

A Cosmic Odyssey: Decades of Discovery at the Palomar Observatory

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Linda Schweizer

Author and astronomer

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Mat Kaplan

Senior Communications Adviser and former Host of Planetary Radio for The Planetary Society

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

Astronomer Linda Schweizer spent countless hours interviewing the explorers who revolutionized astronomy through observations made at California’s Palomar Observatory. She tells their fascinating stories and shares their science in her new book Cosmic Odyssey: How Intrepid Astronomers at Palomar Observatory Changed our View of the Universe. Attention space poets! You might win a Planetfest ’21 t-shirt as Mat and Bruce invite your best efforts in the new What’s Up contest. Hey, it could be verse!

Cosmic Odyssey Book Cover
Cosmic Odyssey Book Cover Cover art for the book Cosmic Odyssey: How Intrepid Astronomers at Palomar Observatory Changed our View of the Universe by Linda Schweizer.
Hale Dome Trails
Hale Dome Trails The Hale Telescope and its dome at Palomar Observatory.Image: Palomar/Caltech

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Trivia Contest

This week's prizes:

5 Planetfest ’21 t-shirts. Our grand prize winner will also receive Linda Schweizer’s Cosmic Odyssey.

This week's question:

To celebrate Perseverance, Hope, and Tianwen-1 reaching Mars, write a poem about one or more spacecraft at or arriving at Mars. Judging will be entirely subjective and capricious. Be profound or make us laugh.

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Complete the contest entry form at or write to us at [email protected] no later than Wednesday, February 10th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

What person’s name has to do with both Earth’s and Mars’ prime meridian?


The winner will be revealed next week.

Question from the 20 January space trivia contest:

What did Galileo want to name the Galilean moons after?


Galileo intended to name the four bodies we now know as Jupiter’s Galilean moons the “Medician Stars” after his patrons, Cosimo, Francesco, Carlo and Lorenzo Medici.


Mat Kaplan: The Cosmic Odyssey of Discovery at Palomar Observatory, this week on Planetary Radio. Welcome, I'm Mat Kaplan of The Planetary Society with more of the human adventure across our solar system and beyond. Cosmic Odyssey: How Intrepid Astronomers at Palomar Observatory Changed Our View of the Universe. That's the new book by astronomer, Linda Schweizer. It documents how George Ellery Hale's crowning achievement, including the 200 inch Hale Telescope, changed our view of everything from our own solar system to the outer reaches of the cosmos.

Mat Kaplan: Linda joins me today for a fascinating conversation. Get your quills out, Bruce Betts wants your poems about spacecraft at or arriving at Mars. Five of you will get the new Planetfest '21 t-shirt for your troubles. Planet Fest is almost upon us, our virtual celebration of the Perseverance Rover, the United Arab Emirates' Hope Orbiter and China's Tianwen-1 begins on Saturday, February 13th. Details are at

Mat Kaplan: Readers of the Downlink, our free weekly newsletter know that the Red Planet isn't having all the fun in the neighborhood. We learned last week that NASA's OSIRIS-REx probe will leave Bennu for Earth on May 10th, that will give the spacecraft one more flyby of the asteroid. Astronauts completed yet another spacewalk outside the International Space Station. Did you know the ISS will soon be getting upgraded solar panels? The originals are starting to show their age.

Mat Kaplan: We also learned that NASA's TES, and the European Space Agency's Cheops spacecraft have discovered a distant solar system with five planets locked in a dance that makes them align now and then, which must be some kind of holiday for anybody living there, wouldn't you think? You can find much more at

Mat Kaplan: Linda Schweizer says she fell early and hard for the stars. That love affair would lead her to a PhD in Astronomy from UC Berkeley. Observations made it three observatories in Chile where she lived for a while, and research published in the Astrophysical Journal. Her favorite job though, was teaching science writing at Caltech, which happens to be the operating entity for the Palomar Observatory, not quite 200 kilometers southeast of the university.

Mat Kaplan: Longtime listeners know of my longtime love of Palomar. Linda feels the same way. She also loves the stunning and revolutionary science that is flowed from the collection of telescopes on the mountain. Now, she has captured the stories and the humans behind that science in Cosmic Odyssey, published by the MIT Press. Linda and I talked a few days ago. Linda, welcome to Planetary Radio. It is a pleasure to have you on and an even greater pleasure to have read this book, Cosmic Odyssey. Thank you for joining us.

Linda Schweizer: I'm very happy to participate. Thank you for inviting me. I'm excited.

Mat Kaplan: Let me just read a paragraph that shows up early in the book, because I think it sets the theme for the book both in terms of your approach to your topic, and the style in which your tales are told. Justice Mount Wilson astronomer Edwin Hubble opened up the boundaries of the universe in the 1920s. So, astronomers at Palomar wrote and rewrote the textbooks of astronomy in the mid to late 20th century. Through the Big Eye, the world encountered quasars, if you prefer and super massive black holes, understood the chemistry that turns stardust into life, and pressed the limits of the known universe relentlessly outward. That is some lovely prose.

Linda Schweizer: Thank you. Well, my purpose in writing the book was to restrict the stories to the science. So, I presented the more basic material in the first chapters and then I followed threads of discovery, some of them from pre-Palomar, all the way to today, I tried to provide context for the discoveries, and I showed the broad data and first images. I conducted several hundred hours of interviews, and I had to navigate some serious egos to get the real story here.

Linda Schweizer: Curiously, while writing I became attached to many of the characters, so I vicariously live through their epiphany and uncertainty. I would wake up in the middle of the night trying to work out kinks in the storyline. Sometimes I felt like I was writing a novel, even though it was about science, but science is novelesque.

Mat Kaplan: You do have some marvelous characters in this book. While it is largely about the science, as you've said, there are just some wonderful men and women, as we will talk about, who were part of this history. There was a reference in that paragraph to the Big Eye, and while it is not the only telescope at Palomar, it is certainly the one that has gotten the most attention, the most good press over the years. Which one are we talking about here?

Linda Schweizer: We're talking about the the 200 inch telescope, which was the largest telescope in the world for something like 45 years, twice as large as the Mount Wilson, 100 inch you could see twice as far into the universe, and everybody was just incredibly excited about it.

Mat Kaplan: You also mentioned upfront that others have written histories of the Palomar Observatory itself, and George Ellery Hale, the man who was responsible for it. Previously, the three previous largest telescopes on Earth. Your purpose really was something else, and you've started to address that. But again, what were you trying to document here?

Linda Schweizer: Well, no one has yet written a book about the comprehensive scientific history of Palomar. They've written about the construction and some science and then there are bits and pieces of the science in various other works, and sometimes the discoveries made at Palomar are not even attributed to Palomar. It's like everybody forgot about Palomar once the bigger telescopes came out. This is a forgotten but very important history of 20th century astronomy.

Mat Kaplan: That is abundantly clear as you read the stories in this book, and I do think of them as stories, detective stories, really. Sometimes they thread back 10, 20, 50 years, across continents, to other teams and telescopes. It's a quote actually, to retrieve a relevant clue as you say in the book. Do you think of these as cosmic detective stories?

Linda Schweizer: Yes, and that's because real life research is a detective story. You're just naming what is, and that's an important concept for me to portray with the agony and ecstasy that goes along with it. For example, radio astronomers and optical astronomers collaborated for years at Palomar to identify strange radio sources. You had people from different continents and different wavelength regions collaborating over many, many years, it's a very long thread, in fact.

Linda Schweizer: Since the Palomar Observatory Sky Survey images, known as the POSS were shared with an international community, others had a chance to explore and discover, was very generous of Palomar to share those. When Russian astronomer who had subpar data, he had photocopies, Xeroxes at the time of these survey images, but lots of determination contradicted Allan Sandage's claim that all type 1 supernovae reached same maximum brightness, it turns out that he won, he was right, and Sandage was wrong. There was a lot of work done over, he said many continents and over many decades, collaborations.

Mat Kaplan: That survey that you mentioned and others that followed it, how much do they represent, essentially, that the foundation of a lot of the other work that you document?

Linda Schweizer: I think you could say that, basically, we're blind without such survey telescopes, like the Schmidt. They produce a roadmap with which we can visually identify sources discovered in other wavelengths. We can find transient objects, we can survey and just find what is out there so that the Big Eye can find it. The Schmidts were used to photograph and identify radio sources, gamma ray sources, they allowed astronomers to compile catalogs of stellar data, interacting galaxies, galaxy clusters, quasars, et cetera, and one of the longest threads involves the supernovae that I just mentioned, they'd been discovered in Andromeda in 1885, the first one, and yet there were very few studies of supernova until the Schmidt cameras.

Linda Schweizer: For a long time, Zwicky was a record holder of supernova discoveries, I think he got up to 120 of them. Now, there are soon to be over a 10,000 found per year.

Mat Kaplan: Wow.

Linda Schweizer: They're pretty fundamental.

Mat Kaplan: That's Fritz Zwicky, of course, who... Well, we're going to bring him up again in a minute. But you also need to say more, you've referred to the Schmidts, the Schmidt cameras, and not everybody out there is going to know what we're talking about. I'm lucky enough to own a Schmidt–Cassegrain. But I didn't know the story behind the Schmidt who came up with this system of optics. Why are these two other quite a bit smaller telescopes at Palomar, up there, they share the mountain with the Hale, the 200 inch, they have been very, very important.

Linda Schweizer: They weren't planned from the beginning because nobody knew about them. It wasn't until Walter Baade who was friends with Bernhard Woldemar Schmidt when he worked in Germany, heard from his old friend that he had been able to solve a major problem in astronomy, which is being able to achieve good focus and clarity out to the very edge of a field of view.

Linda Schweizer: Baade found this out, I think it was about 1934, the 200 inch was still under construction. The design was brought to Palomar and the decision was made with money from the Rockefeller Foundation to build a small one, a test Schmidt 18 inch test Schmidt. Zwicky took that on and he was the sole sitting on Palomar observing with this Schmidt for 12 years before the 200 inch came aboard. It was so successful, that they decided to build a 48 inch that would be more closely matched to the 200 inch in terms of being able to be the scout for that telescope.

Mat Kaplan: That's the relationship, isn't it? It's one has this wide view, and therefore is the Scout, as you say, and then the 200 inch, and now of course, other telescopes, even larger can zoom in, is that fair?

Linda Schweizer: The other telescope, yes, they zoom in, they have a much... The 200 inch has a very tiny field of view. It's like looking through a keyhole at the universe. So, it can see very long and far out into the universe. But if you wanted to cover the whole sky, it would take several human lifetimes to do so. Whereas the Schmidt can cover it very quickly.

Mat Kaplan: Before we go on to talking about the science, which as we said, is really the core of this book, we have to talk a little bit more about Palomar because like you, I think of Palomar, and I've said this before on the show, as a shrine of science. I have climbed that catwalk up to the prime focus cage, way up there near the top of the dome. My colleague, Bruce Betts, who we'll be hearing from in a few minutes as part of What's Up, he observed from it as a grad student. He tells a literally bone chilling story about the hazing he received there on his first night, because nobody told him that you had to dress warmly to sit up there in the so called cage. Do you feel the same kind of awe that I feel and so many feel when they visit and go inside that dome?

Linda Schweizer: Oh, absolutely. Every time I go up there, I always spend quite a bit of time standing inside the dome, all the lights are out, the slit is open, the telescope is wearing their tiny red lights occasionally. I just stand there, and I just admire and I just feel the magnificence of this installation. It's a really spiritual connection, and I think that many people who observe there have it, from all my interviews, everybody just loves going there. In fact, I've been told it's their favorite observatory to observe at.

Mat Kaplan: You document some of the stories. You quote, some of the people that you, thank goodness, were able to interview before we lost them, who talk about that experience of sitting up there. Who was it that had this transcendent experience that you mentioned in the book, because he felt like he was alone in the universe?

Linda Schweizer: That was Martin Schmidt. He was one of my favorite interviewees. Everyone who I knew had observed in the prime focus cage, I asked, "I know what you did up there, I read your papers. But what did you think about and how did you feel?" He was very open with me about his feelings, and he described his experience up there and it was almost mystical.

Mat Kaplan: Yeah. There's another quote, I'll read this from Allan Sandage, who I think you've spent quite a bit of time with and he comes up over and over in the book. He gave you this wonderful quote, "During the period of explosive discovery at Palomar that lasted from 1950 to 1965, I was psychologically in a different world, part of something fundamentally magnificent, that was so much bigger than everyday life. It's the way I suppose religious people would describe some sort of a revelation they have had, some sort of epiphany. It's never happened to me in religion, but it certainly did occur for 15 years straight in my research. Everything was opening, and it was like picking flowers in so many fantastic gardens." You weren't the only one who could come up with great prose in this book.

Linda Schweizer: Oh, Sandage was a fantastic writer. He was a voracious reader. But even though we were old friends, I had to ask him three times for an interview before he agreed. Once he did, the first interview lasted six hours, interrupted with a lunch with Manhattan's which was his favorite drink, but I always heard stories and the interviews would often open with a discussion of the book he had just finished reading. So, he's quite well read, and he was incredibly passionate about astronomy. He was Edwin Hubble's assistant at the 200 inch when he was still a grad student, speaking of grad students, but he was the first and the only for quite a period of time grad student to be able to observe with a 200 inch.

Linda Schweizer: He worked on several groundbreaking projects, including measuring the expansion rate of the universe, and his favorite was understanding how stars evolve. He proposed the first model of how our galaxy itself formed and evolved. Then he finished Edwin Hubble's Atlas of Galaxy. He was in the quasar game for a while and he discovered a new class of objects. He received a lot of nights on the 200 inch telescope. Like the telescope, he was relentless and tireless in his pursuit of his programs.

Mat Kaplan: Some of these characters are going to continue to come up, like I said, Fritz Zwicky, I'm sure, but let's turn more now toward the science that these tales that you tell these detective stories, each chapter of the book explores a different field or line of inquiry and how Palomar helped filled the gaps in our knowledge, or revealed entirely new and stunning objects, as you've already mentioned. We're not going to be able to cover everything, of course, but I'm hoping that we can talk about at least a couple, maybe more, and one of them is the strong, not just an impression I got but the documentation you provide for the fact that Palomar and the astronomers who used it really expanded the universe, they kept making this place where we live bigger, didn't they?

Linda Schweizer: I had to make a joke, the universe was expanding long before there were humans to appreciate that. So, the volume, you might say that it is the volume of the known universe was enormously increased by discoveries from Palomar, and this was done through various standard candles, such as [inaudible 00:16:46] stars and various types of supernovae, and more recently, super-luminous supernovae.

Mat Kaplan: These standard candles, I'm glad you mentioned them, these cosmological milestones, can you talk about why it was that they were so important for finding our way around and seeing just how big the universe is?

Linda Schweizer: They are crucial. The sky appears two dimensional to the human eye, but it's our smarts that must learn to distinguish between a parent and the intrinsic attributes such as size and color and distance and chemical composition, environment, motion, things like that.

Linda Schweizer: For example, you might ask is an object blue because it's hot, or because the molecular structure of its surface absorbs red light, and you have to use standard candles to find distances so that you can study objects with their appropriate size, temperature, et cetera. Otherwise, you're just seeing a screen full of colored dots and you don't know anything about them.

Mat Kaplan: Take into account Doppler, of course, the famous redshift.

Linda Schweizer: Yes, that's part of it.

Mat Kaplan: I think of how the work to find these milestones and make sure that they were reliable standard candles, so called, is a big part of the book. There's even a story of a long effort to determine if one particular type of object was a standard candle, and it turned out it was not. Do you remember the one I'm talking about?

Linda Schweizer: Oh, there's so many answers to that, or so many possibilities. One standard candle that Sandage tried to use was clusters of galaxies in the distance. He started observing clusters of galaxies, and then he plotted their distance and their size and apparent magnitude, until he realized, he was told or learned, he learned really, that they're not standard candles, because clusters of galaxies have evolving galaxies within them, they have interacting galaxies that completely change the cluster over time and change the color of the light coming from the cluster, and you can't depend on them as standard candles.

Mat Kaplan: Which must have been quite a disappointment. But then that's how science goes. You mentioned interacting galaxies, and that reminded me of something else that I was fascinated by. I can faintly remember reading as a very young kid in the 1960s, that galaxies could almost certainly pass right through each other with barely a scratch. Apparently, we know differently now, as you talked about in one of the chapters.

Linda Schweizer: That's a great question. We know differently now, but Zwicky knew differently then, and that was frustrating to him. This thought that galaxies could just sail right through each other was the wrong notion of two researchers who should have known better. One of them was a famous dynamicist. They interpreted a dark gash that was in front of a bright elliptical galaxy as an edge on spiral that was just sailing right through the elliptical unscathed, and they didn't understand the concept of gravitational tides.

Linda Schweizer: While it might be true that the stars themselves really collide, because their size relative to their distances is very tiny, they're not likely to collide with each other, but their positions and velocities are altered in the changing gravitational fields, two galaxies that are moving past each other stars and gas can even be cleared out during this process. That's why we see big arms pulled out, ridges and tails they're called and interacting galaxies.

Mat Kaplan: I have many more questions for astronomer and cosmic Odyssey author, Linda Schweizer, and I'll ask them after this break.

Bill Nye: Greetings, Bill Nye here. Saturday, Sunday, a fleet of spacecraft including NASA's Perseverance Rover is arriving at Mars. Join our live online celebration, Planetfest '21 is February 13th and 14th. I'll be there with explorers. Including Jim Bell, Katie Mack, author of The Martian and the weird NASA JPL Chief engineer Rob Manning and my old friend Phil Plait the bad astronomer. Get your tickets We are going to Mars.

Bill Nye: Mat, was that too much? I got into it there.

Mat Kaplan: No, you nailed it, boss. This realization by Fritz Zwicky, which was rejected by so many others who studied cosmology, it makes it a little bit easier maybe to understand why he was kind of an irascible character. Can you talk about Zwicky?

Linda Schweizer: Oh my gosh, there have been many books written about Zwicky. I don't know what came first, the chicken or the egg. Is he irascible to begin with or was he made irascible? He certainly had a lot of reason to be irascible, but on the other hand, he would swear and call his colleagues spherical bastards if he disagreed with them. That's a person who's a bastard from any angle you look at them.

Linda Schweizer: I wouldn't judge Zwicky, and wouldn't judge his reactions. He did have some reason. He wasn't allowed to observe on the 200 inch, because nobody wanted him on the 200 inch, so they made rules that meant he couldn't. He had a lot of reason, and I don't know what came first.

Mat Kaplan: Yet, in spite of these limitations, self and externally imposed, he's another one who pops up over and over in the book because he contributed to so many discoveries. I think you probably would agree that he was one of the major influencers in the period that Palomar was king.

Linda Schweizer: Oh, absolutely. He was a physicist turned astrophysicist, which is important because he had a good, solid physics background. He was a genius of all trades. He was decades ahead of his colleagues. He compiled monumental catalogs of 40,000 galaxies and 10,000 clusters of galaxies, and especially because of his physics background, he noticed, and this ties into a story we just talked about, about galaxies passing through, he noticed that peculiar looking, or so called damaged galaxies, those that are pristine and perfect, occur in pairs, or small groups.

Linda Schweizer: He thought that was a result of gravitational ties and interactions between them. He also proposed that there was dark matter in the universe. Unfortunately, his work was largely ignored, until more recently, he was far ahead of the crowd. He was a rather pugnacious character, which may have been part of it. He didn't like anyone who had fossilized notions, and who didn't look at things from a physics background.

Mat Kaplan: This is one of those stories that we could spend our entire time dwelling to it, and another recommendation for the book there. But let's go to a different one, here we are talking about expanding, at least our view of how big the universe is. Yet, I find this irony of looking across more than 10 billion light years toward the beginning of the universe, but at the time anyway, not being able to see a mere 25,000 or 30,000 light years to the center of our own galaxy, which is another of these great stories that you tell in the book.

Linda Schweizer: That is a very puzzling story when you look at it from the outside. Absolutely true. You couldn't see the center of our galaxy, even though we were seeing astronomers were chasing quasars. The reason for that is that the disks of galaxies, spiral galaxies, especially, including our own is filled with a kind of smog. It's made up of gas and dust, which absorbs visible light. The smog is produced by the puffed off atmospheres of aging stars. So, the smog is enriched with the products of nuclear burning, like sooty carbon compounds. I have a beautiful picture in the book of one of these stars with all of the shells around it as this stuff is puffed off.

Linda Schweizer: It has nitrogen, iron or silicon, but they all absorb the blue light, and the soot gets enormously opaque in visible light, but it's not opaque in infrared light. A workaround for that was discovered in the late '50s, with infrared sensitive detectors, which allowed us to see the nucleus of our own galaxy, and we could see these inside dusty stellar nurseries where starburst was taking place, and we could also see planetary surfaces.

Mat Kaplan: Since you've mentioned at least one of the illustrations, I should say, the book is pretty richly illustrated and has lots of graphs and charts. Some of these graphs and charts were actually history making. They remain famous today among astronomers, don't they?

Linda Schweizer: Yes, absolutely. One is, Ellen Sandage's, I think it's the front page of one of the chapters, this chart he made, showing how stars evolve, which fundamentally changed our whole concept of stellar evolution, and there are papers too that are just fundamental... Astronomers referred to them only by the first initials of the authors because they're so well know. Eggen, Lynden-Bell, & Sandage is a paper about formation of our own galaxy, was the first global attempt to model how our own galaxy formed, how the entire Milky Way formed.

Mat Kaplan: Mm-hmm (affirmative). Let me turn to a different chapter, chapter 10, which takes up the effort to understand the structure of the universe, something that continues today, doesn't it?

Linda Schweizer: Absolutely. Since light travels at a finite speed, a telescope is kind of like a time machine. When we observe objects far away, we're actually looking at the past when the universe was much younger. With distant objects, astronomers can study the contents of the universe when it was young, when structure began to form, like geologists reading a core sample.

Linda Schweizer: We find that distant galaxies all connect to a cosmic web that's created by dark matter, and by studying the cosmic web in these distant galaxies, we can hope to disentangle the early history of our universe.

Mat Kaplan: Wrapped up with our discoveries revolving around not just dark matter, but dark energy.

Linda Schweizer: Yes, yes, and that dark energy is a discovery, or an implication based on the study of how the universe appears to be expanding. We've always thought that the universe is slowing down in this expansion, which is what you would expect with normal gravity. But when two teams of astronomers observed these Type 1A supernovae, which I've mentioned, out to the very edge of the universe, they discovered that, wait a minute, the expansion of the universe seems to be accelerating. We don't know what dark energy is, but to match dark matter, they grabbed the nomor dark energy to explain it, but we really don't know what it is, but the universe is accelerating. The expansion of the universe is accelerating.

Mat Kaplan: One of the great mysteries remaining in astronomy and astrophysics. We have to talk about chapter 11, because after all, I work for The Planetary Society and it opens by recounting the work of one of our founders, not an astronomer, but a geologist. What was he doing in your book and who are we talking about?

Linda Schweizer: I adored Bruce Murray. He was one of the most fun people to interview.

Mat Kaplan: I liked him too.

Linda Schweizer: He was just a great subject. He came to Caltech as a postdoc in geology. He came directly from the Air Force. He would later become the director of JPL, but he loved to recount his experiences at Palomar, especially with his fellow buccaneer, I called them buccaneers, Jim Westfall. When he wanted to reserve planetary surfaces in the solar system at Palomar, he drove out to the China Lake military Installation. He still had his commission and security clearance. He glad handed the personnel there, he had to explain what glad handed meant to me.

Linda Schweizer: He glad handed the personnel with stories of all the wonderful things you might find at Palomar with the 200 inch. They were so impressed that they stuffed state of the art infrared detectors into his pockets as he walked out. I know, this couldn't happen today, right?

Mat Kaplan: Probably not.

Linda Schweizer: With the agreement that he would tell them how the detectors performed, and what he found out about the planets. This is a funny story, once he took a friend of his to Palomar when Zwicky happened to be up there observing. After what must have been a raucous dinner at the monastery, the friend, who was a psychiatrist whispered to Murray, "Why isn't Zwicky on a leash?"

Linda Schweizer: In general, during dinners, Murray and Westfall felt that they had to be obsequious, so as not to rile the optical astronomers who weren't very happy about their being there. They had these messy, long tubes snaking around, that they had to pull into the telescope, and all these coolers, and they weren't very tolerant, until they realized that actually, you can see better in infrared than in optical when you're looking through the disc when you want to see the center of our galaxy, and then they lightened up a bit.

Mat Kaplan: Now, we realize, infrared astronomy is an absolutely essential area of study, that portion of the electromagnetic spectrum.

Linda Schweizer: Absolutely. It allows you to see further back in the universe, it allows you to see, as I just mentioned, the dusty cocoons where starburst takes place. It allows you to see cool surfaces of planets. It really cuts through a lot of dust that otherwise would block the light and you couldn't observe anything out in the distant universe.

Mat Kaplan: Quite literally. Are you prepared to talk about some of the women who played a role?

Linda Schweizer: Am I ever?

Mat Kaplan: Good. All right. Not by accident, we have so far talked... I think we've only mentioned men who were lucky enough, beginning in the 1940s, to work at Palomar, actually earlier than that. That's not because there weren't women who were very well qualified and certainly deserve to have access to these instruments. Why were they shut out?

Linda Schweizer: It's funny that you asked that, because I've been thinking about it, and why weren't there more female astronomers who were involved in some of these revolutionary discoveries? I realized that was in part because the monastery was set up for only men.

Mat Kaplan: The monastery being the place of Palomar and at Mount Wilson-

Linda Schweizer: The dormitory-

Mat Kaplan: Yeah, the dorms, right.

Linda Schweizer: The dormitories, yeah, where you sleep and you eat and everything, there's a library in there. For a while, women were denied at serving time on that basis. It was a matter of access as much as anything else. It's called the monastery, right?

Mat Kaplan: Yeah.

Linda Schweizer: Until the 1960s you couldn't stay there as a female astronomer because Palomar wasn't designed for cohabitation. The assumption being that only men would be doing this, that is observing, right? It was a widely known secret that Margaret Burbidge had her husband apply for 200 inch time, and she did the observing on her program while he sat in the library and read. Vera Rubin was turned down on her first application for 200 inch time, and then she was able to return in the mid-60s to observe at the 48 inch Schmidt. She stayed at the monastery, her bedroom was on the second floor, and the stairs were closed off to men with a velvet rope. There are two stairwells going up to the second floor. So, one half was all hers.

Linda Schweizer: Henrietta Swope, who worked with Walter Baade was not allowed to join Baade at Palomar to observe. Instead, she had to sit in the offices at Santa Barbara Street, measuring and calculating and plotting. Baade went off to Europe and unexpectedly died, and Swope was left doing all the reduction and the interpretation of the data and publishing the papers.

Linda Schweizer: Then she placed Baade's name first on that paper, she admired him, I guess. Vera Rubin didn't return to observe on the 200 inch telescope until the 1980s. Although today, an observatory is named after her with an eight meter telescope. So, why were women invisible, you ask? I think it's in part because they weren't allowed to be visible. It's that simple. Women weren't allowed into the, "fantastic gardens" that Sandage mentions, in order to pick the flowers of discovery.

Mat Kaplan: How different is the situation today?

Linda Schweizer: Oh, it's completely open today. anybody can observe there. Anybody can stay there at the monastery.

Mat Kaplan: Thank goodness.

Linda Schweizer: As a graduate student at Berkeley, Jill Tarter worked on models predicting the colors of dwarf star atmospheres. Since her models predicted that dwarfs changed temperature, she chose to label them brown because it's a mixture of blue, red and yellow. So, she covered all the bases. She didn't observe at Palomar, but the story of brown dwarfs continues with a team at Palomar that had a new instrument and they joined an international race that had already been in progress for three decades, not being able to find brown dwarfs. And graduate student, Rebecca Oppenheimer, then known as Ben R. Oppenheimer, was part of that team, and she ended up discovering the first brown dwarf in the mid-1990s, then told me that she began leaping with delight around the dome at the thought of what lay in store with this discovery.

Linda Schweizer: She, by that time, of course, was an accepted member at Palomar of the monastery. She could stay there any time. She then went on to lead a team to design and construct an ingenious state of the art instrument that for the first time can simultaneously take spectra and images of exoplanets, and she's doing this from Palomar. She's a real success story and certainly a female presence at Palomar.

Mat Kaplan: Great evidence of how much things have changed since those days in the '40s and '50s, and how much better it is for all of science and for these researchers, like Rebecca. Of course, I think I had told you that I was surprised to read that old friend of Planetary Radio, Jill Tarter, not only was an old friend of yours, but I didn't know that she had come up with the term brown dwarf.

Linda Schweizer: Yeah.

Mat Kaplan: Readers of Cosmic Odyssey should not stop at the end of the last chapter, you really need to read the acknowledgments that you've included, they extend over several pages. I'm very proud to say that you credit many people who have been guests on Planetary Radio. Right at the end, you provide a credit, sort of a statement of gratitude, and it allowed me to discover that you and I have something in common, and that is spending a good part of our childhood at the Griffith Observatory, on that hill above Los Angeles.

Linda Schweizer: Wonderful, wonderful. We may have bumped into each other.

Mat Kaplan: We might very well have. There were times in our early little family life when we lived very close to the observatory. My parents knew how much I loved going there. It had such a huge role in leading me in the direction that it did, talking to people like. Sounded like it had a big role in you becoming the astronomer that you are now.

Linda Schweizer: It absolutely did, yes. I was fascinated, I didn't understand everything at the beginning, but I worked at it, and it led me to do every single school report was on some astronomical subject; spectroscopy or the planets or whatever, every single one, and my teachers tolerated it, fortunately.

Mat Kaplan: Good for them. Is there an ongoing role for Palomar? All of the instruments up there, as we see ever larger telescopes, both ground and space space coming online? Here we go, hoping that the James Webb Space Telescope will unfold properly and begin its work this year. Then of course, those new giant telescopes, which are under construction right now. Is this wonderful, old shrine of science going to play a role?

Linda Schweizer: Absolutely. Palomar is an ideal testbed for the sophisticated instruments that are under construction. It's a short three hour drive, from Caltech to Palomar. So, instruments can be built in the labs at Caltech and then checked out periodically at the telescope. Adaptive Optics has brought Palomar considerably, and it's played a big role in their sustainability, as has the coronagraph which is a device that blocks out light from bright stars.

Linda Schweizer: Te mirrors are intrinsically very high quality. The telescopes are incredibly sturdy. So, you can just hang whatever you want from those telescopes, and they'll still work like a Swiss watch. They were built like battleships, they're not going anywhere.

Mat Kaplan: I am so glad to hear that, and I look forward to making-

Linda Schweizer: Me too.

Mat Kaplan: ... someday I hope that we can visit up there together.

Linda Schweizer: That would be wonderful, yes.

Mat Kaplan: Just one other observation that you make in your last chapter of the book, which is titled Astronomical Exotica, that that captured my imagination. It was about how so much of what you write about in the book lives on a continuum, if you will. Could you talk about that?

Linda Schweizer: I was talking about how planets and stars had always been considered separate kinds of entities. But when brown dwarfs were discovered, astronomers realized that they had found the missing link between planets and stars. The highest mass are the stars and the lowest are planets, and they're linked by a sequence of brown dwarfs. So they all form a continuum of increasing mass from planets [inaudible 00:39:40] stars. Only stars generate energy. But what a wonderful idea that is, right? Early on, when you've got only a handful of objects you've observed, then it's easy to categorize them and see their differences. But when you observe more objects, you realize there are fine gradations, which sometimes work into a continuum.

Mat Kaplan: I think of what you document in the book as a continuum of human discovery that is representative of so much of science.

Linda Schweizer: Yes, discoveries are building blocks. Sometimes a block falls, sometimes it's knocked off, but the general trend seems to be upward that we're discovering more and more and putting all of these building blocks together to reformulate our picture of the universe.

Mat Kaplan: And building something magnificent with them.

Linda Schweizer: Yes.

Mat Kaplan: As I think you have with this book, Linda. Thank you very much for for writing it and for joining us on Planetary Radio to talk about it.

Linda Schweizer: You are very welcome. I had a great time.

Mat Kaplan: I'm glad. The book is Cosmic Odyssey: How Intrepid Astronomers at Palomar Observatory Changed Our View of the Universe. It was just published in November of 2020 by the MIT Press, no surprise there. You can find it in all the usual places. You can also find an opportunity to win your own copy, when we get to this week's Space Trivia Contest with Bruce Betts, coming up in just moments. Linda Schweizer has a PhD in Astronomy from UC Berkeley and she has observed at many observatories around the world. Published research in the Astrophysical Journal, teaches science writing and was a visiting scholar at Caltech, the California Institute of Technology, all while raising four daughters.

Mat Kaplan: Time for What's Up on planetary radio. We are joined by the Chief Scientist of The Planetary Society. Bruce Betts, he who used to long time ago go down to Palomar and apparently freeze. Have you ever warmed up?

Bruce Betts: No, not really. Long time ago. Yeah, I was back there when they were building it back in the '40s.

Mat Kaplan: Yeah, you really have well preserved.

Bruce Betts: We had electric lights, man, it was okay. I was so scared, they made... We're going to the Prime Focus. Take everything out of your pockets. "Oh, why?" "You don't want to drop a coin on the Palomar 200 inch mirror." So, it's a bad thing. Turns out they keep those domes cold during the day, someone should have told the brand new grad student who showed up in a t-shirt, after the night that had been 30 degrees.

Mat Kaplan: You didn't have so much as a hoodie?

Bruce Betts: No. I did next time we went up there, I was very, very warm.

Mat Kaplan: I'm glad you survived and a little envious, although, as I told Linda Schweizer I have walked up there.

Bruce Betts: I learned a lot, and I spent 12 nights at Palomar not getting any data but that left more time for exploring the telescope and playing Cowboy Billiards.

Mat Kaplan: Cowboy Billiards? All right, you'll have to describe that a different day.

Bruce Betts: But let's talk about the night sky, that stuff you can see with your eyes. In that evening sky, Mars is fading but it's still looking like a bright reddish star in the evening in the south, and it is fairly close, if you look over to the left to Aldebaran, which is a reddish star that they're actually pretty similar in brightness right now.

Bruce Betts: The other way you can do it is find Orion, which is quite stunning as always in that evening sky, in the evening east, southeast. If you follow the Orion's belt, you draw a line in one direction you come to Sirius, the brightest star in the sky. If you go the other direction, you come kind of close to Aldebaran, reddish star in Tauri, and you go farther, and you'll see reddish Mars. So, it's a whole little party.

Bruce Betts: Here's a fun fact, Mat, the day that Perseverance is going to land on Mars, the 18th of February, the moon will be really close to Mars in the night sky. On to This Week in Space History, 50th anniversary of Apollo 14 landing on the surface of the moon and learning stuff with people and golf clubs. We've got a great article on our website,, Mat may even put a link from the show page.

Mat Kaplan: We might indeed.

Bruce Betts: On to [inaudible 00:44:24] I hear you may have been speaking of the Palomar 200 inch Hale telescope.

Mat Kaplan: Indeed and the other telescopes out there.

Bruce Betts: The 200 inch Hale telescope is about 500 tons, but it's kept so well balanced that only one to three horsepower motors are used for slowing and tracking. For the first 65 years, it was only a one twelve horsepower motor that was used for tracking. Whenever they add instruments they have to rebalance the telescope to keep it all perfectly balanced.

Mat Kaplan: As Linda Schweizer said, like a fine Swiss watch, except built like a battleship.

Bruce Betts: That's a good analogy. It seems like a battleship, but then it does these incredibly precise things, as do all of those big telescopes out there. We move on to the trivia contest, and I asked you, what did Galileo want to name what became known as IO Europa, Ganymede, and Callisto also called the Galilean satellites, what or who did he want to name them after? How did we do, Mat?

Mat Kaplan: A huge response, the biggest one we've had in quite a long time, and a bunch of first time listeners. So welcome to all of you. First time winner, although a longtime listener, Thomas [Ancillary 00:45:44] in New York. Thomas said, "The Galileo wanted to name the moons the Cosmian stars after Cosimo de' Medici or the Medician stars, which would honor all four brothers in the Medici clan.

Mat Kaplan: He eventually settled on the latter. Who are those brothers? Cosimo, Francesco, Carlo, and Lorenzo, I should have rolled the R on that one. Is he correct?

Bruce Betts: He is correct. An early example of the fine tradition of naming things after your sponsors, which was not as popular elsewhere in the world, hence the reason we came up with those mythological names tied to Jupiter.

Mat Kaplan: Thomas, congratulations, and it is about time. You have won yourself a Planetary Radio t-shirt. So, we'll check with you about what size shirt you would like to get from The Planetary Society Store at Chop Shop. That's the, if you want to check out all of our merchandise. A lot of people speculated What if those names had stuck? Marcel John [Krigsman 00:46:52] in the Netherlands. He says, "I can't wait for the Francesco Clipper Mission." Pretty clever.

Mat Kaplan: Mark Moffett in Georgia, he first read of Galileo's discovery as a child, took his telescope out, found the moons. He later took a certain Bruce Betts' online class about the solar system and learned so much more.

Bruce Betts: How good. Still out there at, free, by the way.

Mat Kaplan: Joseph [inaudible 00:47:23] in Nevada just read all about this in Alien Oceans by Kevin Hand. Of course, Kevin hand at JPL, expert on ocean worlds wrote that great book. We talked to him about it last year. To quote the book, he even named them The Stars of the Medici, in honor of the Medici family since they were funding his research. He adds in parentheses, (Galileo was no idiot). Quite the opposite.

Mat Kaplan: Ian Jackson in Germany, "Not officially known but Galileo visited the moons as excellently documented by Kim Stanley Robinson." It's true, you got to read Stan's book, Galileo's Dream, it's very entertaining. Stephanie Delgado in Arizona, within the family, according to Stephanie, not just Lorenzo, but Lore, the evil twin. Live long and prosper, Stephanie. Finally from our Poet laureate, Dave Fairchild in Kansas, "When old Galileo unveiled how moons around Jupiter sailed, "We'll call them," He said, "For the clan Medici." I'm glad that his naming scheme failed."

Mat Kaplan: We also got a great poem from Jean Lewin in Washington, it's too long for us to read here, but maybe we'll put it on the show page at

Bruce Betts: Radio.

Mat Kaplan: We're ready for another one.

Bruce Betts: For our next contest, I will challenge your creativity. To celebrate Perseverance, Hope and Tianwen-1 arriving at Mars, your assignment is to write a poem about spacecraft, one or more at or arriving at Mars. Write us a poem and we will of course, judge it in a completely objective way, or subjectively go with whatever makes us laugh or is profound. We don't know. But write us a poem and submit it to When are you going to win, Mat?

Mat Kaplan: You might think that boy, this one's in the bag for our poet laureate or some of the other people who regularly submit poems, but we've got five prizes to give away and each one of them is the brand new Planetfest '21, To Mars and Back t-shirt. Why? Because it's coming up, it's the 13th and 14th of February. You want to learn more It is a really cool... I cannot wait to get my t-shirt. Then our grand prize winner will get not only the t-shirt, but a copy of Cosmic Odyssey by Linda Schweizer. Not bad, huh?

Bruce Betts: No, it's good stuff. When do they need to get those in by, Mat?

Mat Kaplan: Oh, there's that, isn't there? By, let's say February 10th, Wednesday, February 10th at 8:00 AM Pacific Time.

Bruce Betts: All right, everybody go out there, look up the night sky and think about which extraterrestrial ocean you'd most like to scuba dive. Thank you, and good night.

Mat Kaplan: There's so many to choose from. I think I'll go with the obvious one, Europa, and it sounds like it'd be a lot of fun, it's just the elevator ride down through the ice that I don't think I would enjoy very much. He's Bruce Betts, Chief Scientist of The Planetary Society, who joins us every week here for a warm and toasty, What's Up.

Mat Kaplan: The recording of my great conversation with Her Excellency, United Arab Emirates Minister for Advanced Sciences, Sara Al Amiri is now on YouTube. We've got that link and much more on this week's episode page at Planetary radio is produced by The Planetary Society in Pasadena, California, and is made possible by its farsighted members. Join them at Mark Hilverda is our Associate Producer, Josh Doyle composed our theme which was arranged and performed by Peter Schlosser.