Planetary Radio • Jun 05, 2019

Starchaser: Extraordinary Astronomer Jay Pasachoff

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Jay Pasachoff

Field Memorial Professor of Astronomy for Williams College

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Mat Kaplan

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

Jay Pasachoff visits Planetary Society headquarters for a conversation about the latest edition of his and Alex Filippenko’s monumental textbook The Cosmos. But that’s just the start of a discussion that explores solar astronomy, art and science, the history of astronomy and Jay’s nearly 60-year history of total solar eclipse observations. The Planetary Society’s LightSail 2 may look like LightSail 1, but Jason Davis tells us there are important differences between these spacecraft, beginning with their missions. What’s Up brings another opportunity to win Alan Stern’s great book, Chasing New Horizons in the space trivia contest.

Jay Pasachoff
Jay Pasachoff Jay Pasachoff in 2005 standing in front of the largest telescope in the world, the 10.4-meter reflector in the Canary Islands.Image: Jay Pasachoff
Total solar ecilpse
Total solar ecilpse The Williams College Eclipse Expedition was in Salem, Oregon, for the total solar eclipse that occurred on August 21, 2017.Image: Jay Pasachoff and the Williams College solar Eclipse Expeditions

This week's question:

What is the alloy that the LightSail 2 booms are made of? These long booms pull the sections of the solar sail out of the body of the spacecraft.

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, June 12th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

What is the brightest pulsar as seen from Earth at radio wavelengths?


The answer will be revealed next week.

Question from the May 22 space trivia contest:

Name everyone who has served as NASA Administrator more than once. Terms of office must be non-contiguous or separated by some amount of time. This means Acting Administrators who are immediately appointed as Administrator don’t count!


The only individuals who have served as NASA Administrator more than once without going immediately from Associate Administrator to Administrator are James Fletcher and Alan Lovelace.


Transcribed by Planetary Society volunteer Jake Bathman:

[Mat Kaplan]: Extraordinary astronomer, author, and eclipse chaser Jay Pasachoff, this week on Planetary Radio. welcome. I'm at Kaplan of the Planetary Society with more of the human adventure across our solar system and beyond. As you'll hear, Jay Pasachoff doesn't like the term "eclipse chaser." His alternatives for that title are part of our wonderful conversation with him that will touch on art, poetry, mysteries of the universe, and the history of civilization. Jay also makes a cameo appearance in this week's What's Up segment with Bruce Betts. You might want a copy of Chasing New Horizons in the space trivia contest. Why is the launch of a second LightSail spacecraft so important to the Planetary Society? That's just one of the questions answered by the Society's Jason Davis in our opening segment. Jason you already wrote last week, that was your May 30 entry in the [00:01:00] Planetary Society blog, LightSail 2 Arrives in Florida, that our spacecraft is at its final destination at least before it takes off for Earth orbit. And it's what inside the Prox-1 carrier now?

[Jason Davis]: Yeah, it's already inside the spacecraft. It's been there since it was integrated back into Mexico at the Air Force Research Lab and then they shipped him both as an integrated unit down to Florida, so presumably at some point very soon it'll get attached to the launch vehicle. From there, it's launch time. So it's coming up fast.

[Mat Kaplan]: And as far as we know that launch date is still set for June 22nd?

[Jason Davis]: Yes, and we have a time now: 11:30 in the evening. So it's going to be a night launch for the Falcon Heavy.

[Mat Kaplan]: You and I will be there watching and that really will be spectacular.

[Jason Davis]: Yes. Yeah, that should be something to see.

[Mat Kaplan]: You have this new piece, which is out today as this program is published on the Planetary Society website, that being [00:02:00] June 5th, and it talks about the differences between LightSail 1 and LightSail 2, which I guess we've gotten a lot of questions about?

[Jason Davis]: Yeah, we wrote this just to have something to refer to because we do get this question a lot. What are the differences between the two spacecraft? You know, they're they're very similar and from the outside they look almost alike, but there are some key differences. So that's why we wanted to publish this ahead of the launch.

[Mat Kaplan]: Now, the big difference is nothing internal to the spacecraft. It's just where it's going, which we've talked about on the show before but just very briefly, we're going into a higher orbit this time. Why is that?

[Jason Davis]: Yeah. So atmospheric drag is still a pretty dominating force in low earth orbit. You know, the International Space Station, which is about 500 kilometers, has to raise its orbit every now and then with thrusters because it's slowly being dragged down. So we need to go to a higher orbit where the thrust from solar sailing can overcome that and that generally you can barely overcome it around 700 kilometers. We're going to about 720 [00:03:00] kilometers in that should just be enough to where we can make a measurable change in the orbit from solar sailing.

[Mat Kaplan]: We'll be able to sail on the light of the Sun for the first time at least at least for a Planetary Society spacecraft. I know there are software upgrades as well based on what we learn from LightSail 1, but let's go on to a couple of hardware improvements including the presence this time of a momentum wheel, I still like to call them reaction wheels, maybe as a tribute to Isaac Newton.

[Jason Davis]: But yeah, yeah exactly. The the right-hand rule where you curl your fingers in the direction something's spinning and then your point your thumb up and that's the direction of the force that's imparted. At least, I think I have that right, I'm obviously not a physicist here.

[Mat Kaplan]: But I like that.

[Jason Davis]: Bigger spacecraft use sets of these to do all of their attitude control meaning to turn around in space, and they spin one of these things up and it actually rotates the spacecraft in a certain direction. LightSail doesn't need three momentum wheels because it's a smaller [00:04:00] spacecraft. So it uses these little torque rod things to do its turning. But when it turns its solar sail back and forth that is a pretty big force required to do that when the sail is out. So it needs a single momentum wheel to do that. It makes two 90-degree turns each orbit using that momentum wheel. So the first spacecraft did not have one of those installed because we didn't need one but the second one definitely does so that's one of the big differences in hardware between the two spacecraft.

[Mat Kaplan]: So we'll be keeping that momentum wheel pretty busy, it sounds like, if it has to do this twice every what 90 minutes or so I assume.

[Jason Davis]: Yeah, exactly.

[Mat Kaplan]: And the torque rods we talked about before, they're just so cool. Using the Earth's magnetic field to adjust the position or at least the orientation of your spacecraft. Really what is cooler than that?

[Jason Davis]: Yeah. Yeah. It's like a magical free form of attitude control. It's pretty mind-blowing, you know, and I didn't even know about these until you know, I started learning about the LightSail mission several years ago. Actually, I just heard [00:05:00] people that have been following StarLink spacecrafts that SpaceX launched, they use torque rods for some of their orbital changes or rather attitude control changes as well. So yeah, these are pretty common. It's pretty neat concept.

[Mat Kaplan]: I'll be darned. I didn't know that about LightSail until recently either and I sure didn't know it about those new first in that constellation from SpaceX. All right, finally, we have these little reflectors on LightSail 2 that were not on LightSail 1 and they mean that we have this much in common with that Beresheet spacecraft that the folks in Israel sent to the Moon and who knows those mirrors may still be in little pieces somewhere on the Moon. Why are they there on LightSail 2?

[Jason Davis]: Basically when you want to find the distance to something really precisely you can shoot a laser at it. And when the reflection comes back you measure how long it took for the reflection to come back and that will give you a distance estimate because we know the speed of light is a universal constant. [00:06:00] Beresheet had them because we were going to use them as kind of a navigation system in orbit. There're actually retroreflectors left by the Apollo missions on the surface of the Moon the we can still to this day shoot from Earth and tell how far the distance is between the Earth and the Moon. Beresheet had one because you know, NASA is really interested in going to the Moon and they need to kind of build up a navigation system for when spacecraft are in orbits. So orbiting spacecraft can zap these things and tell how close they are to the surface essentially and that's what we're going to do with LightSail. We're going to be able to zap it from the ground and determine exactly where it is in space. Now, that's really important for LightSail because we're trying to measure the change in its orbit from solar sailing. So we need really precise orbital measurements. And that's one way we're going to do it. LightSail 1 had a few of those small mirrors on it, but for LightSail 2 they wanted to make sure that we get that signal back and added a cluster of mirrors on the bottom of it. So that should be [00:07:00] enough to get that return signal until where it is.

[Mat Kaplan]: More extreme coolness, bouncing a laser off of a solar sail. Almost a little preview of how light sails may be driven outside the solar system. By much more powerful lasers will see. Jason, thank you. I sure look forward to joining you in Florida on and even a little bit before June 22nd for that launch.

[Jason Davis]: Yep. Sounds fun. I will see you there.

[Mat Kaplan]: That's Jason Davis, our embedded reporter with the LightSail project, also the Digital Editor for the Planetary Society. When I learned that Jay Pasachoff would be back in Pasadena, I hoped I'd have another opportunity to sit down with this astronomer and astrophysicist who [00:08:00] has witnessed eclipses around the world for nearly 60 years. As you'll hear, Jay has contributed much more than good science to society. We'll talk about his first love solar astronomy before we move to his love of astronomy's long history and its ties to artistic endeavor. Sharing his passion has always, always been part of his work. Jay Pasachoff, welcome back to Planetary Radio. It's great to have you here in the Planetary Society studio for a conversation.

[Jay Pasachoff]: Well, I'm really glad to see your new studio and I've known a lot of people of the Planetary Society for many years going back to when I was a Harvard undergraduate and Carl Sagan was assistant professor there and I've met Bruce and Bill and and it's a very Great pleasure to be here with you.

[Mat Kaplan]: Bruce Murray, Bill Nye. I bet you've run into Lou Friedman, too.

[Jay Pasachoff]: Can't miss Lou.

[Mat Kaplan]: You mentioned to me when we saw that nice portrait of your former professor outside and I didn't realize that he had been a Harvard before he went to [00:09:00] Cornell.

[Jay Pasachoff]: Yes. He was a very inventive then. I remember being With him at some party at night and there was some little game being played where you imagined a room and most people said, all right, it's a 6x9 room and we have a library or something, but he added extra dimensions to the room when he gave his answer. So even then he was a very inventive fellow.

[Mat Kaplan]: Yeah and lucky for Cornell they were the ones who gave him tenure and he spent the rest of his career there.

[Jay Pasachoff]: My understanding was he was a little too inventive for the Harvard astronomy department at that time and they weren't sure he was going to settle down and do grinding astronomy. He was interested in too many other things so they didn't give them tenure.

[Mat Kaplan]: Lucky for us he never did settle down that way.

[Jay Pasachoff]: Well, the last thing he said to me when I visited him at Cornell is that he said, Jay, we ought to see each other more often. So I remember that but unfortunately he died too young.

[Mat Kaplan]: That's a lovely tribute, though. You and another one of my [00:10:00] contemporary science astronomy heroes, Alex Filippenko, are about to publish the fifth edition of The Cosmos: Astronomy in the New Millennium. I'm reaching over for the paperback copy that you brought in and even the paperback is so heavy I have to strain a little bit. It's already being called the best written introductory astronomy textbook on the market, but then you've been out there for a long time. This has been the first formal introduction to astronomy for countless students. Congrats, first of all...

[Jay Pasachoff]: Thank you very much.

[Mat Kaplan]: ...on this pending publication, scheduled for June 30th. Right?

[Jay Pasachoff]: Well, we have the first copies there have been printed and they're just on a boat coming from China at the moment where the books were printed, but they were edited in mainly in the United Kingdom.

[Mat Kaplan]: And you told me that this is maybe the only copy currently in the United States?

[Jay Pasachoff]: Well Alex has a copy too so I think maybe there are two copies in the United States, but it's expensive to bring things by air and the bulk come by [00:11:00] sea, but we're really very very pleased with it. There is so much new stuff new stuff in every chapter and the history of the book and even before Alex joined me four editions back, NASA once made a study of how their space projects were covered in the general public by looking at all the editions of my book that had been out, up to that time.

[Mat Kaplan]: Wow. That's a nice compliment. It's only been six years since the 4th edition. I guess a lot has happened since then, right? What do you think are some of the highlights?

[Jay Pasachoff]: Well, we've put the eclipse of 2017 on the on the cover and there's a lot about the sun and the sunspot cycle as it goes up and down at the moment very down and discoveries with the spacecraft that are that are being made about the Sun. So we keep advancing that. There are certainly new things of interest in the planetary sciences. The Curiosity is [00:12:00] roaming around. We have latest pictures from from Curiosity. Cassini has spiraled into Saturn and and we have some great images and discussions of that. At the last minute after it was all closed I've ran the Pluto chapter by Alan Stern and he said wait a minute, there's some new newer stuff. So in fact, we went out to him and Cruikshank and a few other people at the last minute. The publisher really was getting angry with me for all the last-minute things we were doing after after closing but we have a whole lot of statements about what the latest ideas about Pluto are and we did get in a picture of Ultima Thule which you and I were together at the flyby on on January 1st.

[Mat Kaplan]: New Year's Eve, yeah.

[Jay Pasachoff]: So we receive, yeah. Yes. In communicating extraterrestrial intelligence. There's new tries that have been made to sending message out, but [00:13:00] maybe the biggest thing as of this week is the question of how old the universe is. So and Alex Filippenko, my co-author, was the only guy who was on both of the Nobel Prize teams for the acceleration of the expansion of the universe. So I was actually even a little skeptical when he was redoing the chapter about the Hubble expansion of the universe and whether there was a real discrepancy between the value for the age of the universe at the speed of expansion that we get from the Planck spacecraft and the value we get from supernova observations, but it's a big thing now. There's a new article by Adam Riess there. And and I'm at the Carnegie observatories on sabbatical this semester from Williams college and I see Barry Madore there who's working with his wife Wendy Friedman on their values which are now significantly differing from the the Planck value which [00:14:00] requires a model to update the structure at the very early Universe to what's going on now. So, somewhere there's a problem and it's looking more and more as though it's a serious problem.

[Mat Kaplan]: Challenging everything we had come to believe or at least accept in theory about our universe since that Planck constant is so basic to how we understand the universe...

[Jay Pasachoff]: Hubble, the Hubble constant.

[Mat Kaplan]: I'm sorry. I was thinking of that the Planck length. Doesn't that just make this business that you're in that much more exciting?
[Jay Pasachoff]: Well it sure it's very exciting and the Hubble constant when Hubble was doing it was in the 500s and then when I started doing my book some decades ago, there was a discrepancy between Sandidge and Tommen here in Pasadena with a value of about a hundred and du Vogelare from University of Texas at 50 or maybe vice versa. I think but then there was a fight between a hundred and fifty and now we're fighting between [00:15:00] 74 and 68. So there's... and the precision is down to plus or minus less than 2 so there have been tremendous advances and we're talking about some details and now that we're in this this detail, we can really test some fundamental ideas about the universe and how it evolved.

[Mat Kaplan]: I got another one that I think I'm pretty sure made it into this new edition of the book and that is the detection of gravity waves.

[Jay Pasachoff]: Oh certainly there's a lot there's a lot about LIGO. I was very glad to be here at Cal Tech and on sabbatical when the LIGO announcements were made and I watched from the auditorium at the astronomy building... astrophysics building at at Cal Tech, which incidentally for those of you who are spectral nerds it's a 1218 East California Boulevard and 1218 is the wavelength of the lyman-alpha line of the hydrogen. So that's why they chose that. So anyway, there's a lot about LIGO. And [00:16:00] I've been to the sites in Livingston, Louisiana and in Hanford, Washington but when I left that that wonderful press conference and and comments that were being made that day, they gave us coffee cups and bumper stickers. So I was really sorry I hadn't hung around the print shop a couple of days in advance and they were making things to get a little advance notice. I have actually had to move some of the discussion of LIGO and gravitational waves from the neutron star chapter where it had been with with supernovae and move it into the black hole chapter because the first we had the merging the merging black holes. Actually, I've been working on the LIGO interest for decades because I did a book called Invitation to Physics with Richard Wilson around 1980 and I visited Rainer Weiss at MIT at that time. He showed me some of the equipment. That was interesting, but he didn't really convey to me or maybe I didn't understand that the [00:17:00] discovery was going to be decades off. I thought this was going to actually find the the stuff at the time. Anyway, my wife and I went up from a meeting of the American Geophysical Union a year or so ago for my second visit to LIGO in Louisiana. And I found out why it's in Louisiana because they wanted it as far as possible from Hanford Washington. So first they looked in the east coast, but it turns out that the waves of the Atlantic Ocean hitting the shore at the east coast of the United States is so strong that the vibration would have been a problem and by moving it nearer to the Gulf Coast the the waves on the Gulf Coast aren't as strong and it is an hour or two inland, also.

[Mat Kaplan]: You know, we have talked about the exquisite sensitivity of those detectors, and apparently it's only getting better.

[Jay Pasachoff]: I understand that there are online now in the getting a couple of events a week.

[Mat Kaplan]: Wow. It would have been enough to see the confirmation of these gravity waves that had been predicted [00:18:00] so many so long ago by we know who, Albert, but does this also mean that some day you may be adding a chapter to The Cosmos about gravity-based astronomy?

[Jay Pasachoff]: Well, I certainly hope so. In fact when I came out with my first edition, before Alex came on, there was a chapter on the outer planets and then the next year NASA went by Jupiter and the next year Saturn and I kept adding chapters and now there's a chapter on Jupiter and a chapter on Saturn and the chapter on Uranus and Neptune. So I do like to keep up and expand on these things and it's just been wonderful to follow the progress of astronomy in this time.

[Mat Kaplan]: More of our very special conversation with Jay Pasachoff. This is Planetary Radio. What's new in solar astronomy?

[Jay Pasachoff]: The Parker solar probe is going from NASA up close to the Sun and it's doing it in a gradual way in a series of [00:19:00] ellipses that gets closer and closer. So from my point of view as a solar astronomer who studies eclipses, I've been trying to figure out the lines of sight that would intersect the kinds of of matter around the Sun that the solar probe is in at any given time. But we are able to get improved observations of the solar corona. And right now I'm busy in in getting ready for the July 2nd total solar eclipse that we're going to observe from Chile. I was very pleased over the last month and then technically definitely yesterday to get the confirmation of a grant from the National Science Foundation for three more years of my scientific study of the eclipse with my students from Williams college and colleagues from around the world. We will be in Chile on the Centerline. And four of the people will be at the top of Cerro Tololo at the observatory there at 7,500 [00:20:00] feet. The corona is just different every time. Maybe they'll be some eruptions. There were some a couple of eclipses ago that we could study. At this last eclipse where we have these wonderful observations from Oregon and we compare it with observations made at other places across the country. We can compare velocities in the corona how quickly things change we do see the temperature of the corona change over the solar activity cycle what matches the sunspot cycle and at solar minimum the corona is a little little cooler. We monitor that especially with some spectral lines from iron. And particular back in 1869 a spectral line was discovered in the corona from iron that has lost 13 of its normal 26 electrons and it had to be a million degrees to to do that though it took till around 1940 for that to be figured out. And then there's another another spectral line from iron [00:21:00] 10, which is 9 times ionized iron. So that's a little cooler. We can see the ratio of those two intensities change from solar maximum to solar minimum. I work with a very talented instrumentationist, Eras Vulgaris from Thessaloniki in Greece, who has now modified a special filter that we borrowed from the Big Bear Solar Observatory here in California, and he's able to change the wavelength to match argon 10 that's 9 times ionized argon and that gives us an image of the corona and a yet another temperature region. So we'll be trying that out for the first time from Cerro Tololo on July 2nd.

[Mat Kaplan]: I wish I was going to be there with you. I thought I might be able to make it but it's not going to happen. So have typically wonderful time down there. Are we closing in on understanding the great mysteries about the sun like why the corona is so very incredibly hot?

[Jay Pasachoff]: Well, what I like to say is that problem has been [00:22:00] solved and I've been saying for a while the problem has been solved in 12 different ways by 12 different people. But actually then I went to a meeting six months ago and the speaker Steve Cranmer from Boulder gave a list of 19 different people who are different different theories. So we're sure it has something to do with the magnetic field on the sun, which was discovered right near here by George Ellery Hale in 1908, on Wilson. But just the details of what kind of loops of magnetic material might be vibrating for example, or what kind of little flares called nanoflares might be might be doing is something that we can test a bit and and one of my sets of eclipse observations that we made in 2017 together with a colleague from MIT, Mike Person, who had a one of our filters in that coronal iron 14 line and iron 10 line, so called coronal green line and red line, [00:23:00] we observed several times a second and the predictions of some of those theories are different whether they're a short periods or longer periods or no periods. If it's just those nanoflares going off all the time. So some of what we're doing at eclipses is testing the theories that have been advanced and trying to distinguish among them.

[Mat Kaplan]: You obviously have an endless, literally endless, fascination with our star.

[Jay Pasachoff]: I guess that's fair. It started back in high school when I was a member of the Amateur Astronomers Association in New York, although I am about to go next month to the 65th reunions of my sixth grade class from PS114 in the Bronx and when we started having reunions for the 25th, they said Jay you're the only one who's followed through with his original plan, idea. So I have validation that I really was interested mainly from the Hayden Planetarium in New York, I [00:24:00] guess in astronomy all that time and I found a picture from high school with a telescope I had built. When I went to Harvard as a freshman, Professor Donald Menzel, the director of the observatory was a distinguished astronomer who observe many eclipses and study the solar coronalsphere especially and he was giving freshman seminar the first in a series of freshman seminars that Harvard was trying to use to bring senior professors together with the the elementary students. And it just happened that two weeks after we started my freshman year there was a total eclipse of the Sun that began over Massachusetts. And he borrowed an airplane a DC-3 from North East Airlines, neither of which is in service at the moment, and and took our freshman seminar along with a few friends aloft and the started me off on solar astronomy or eclipse astronomy.

[Mat Kaplan]: What a great start. You know, I have to ask, how many total eclipses have you observed now, [00:25:00] do you have any idea?

[Jay Pasachoff]: Well, there are people who keep who keep track. Bill Kramer has a website at It does show it and I do have a list. This will be my 35th total solar eclipse that's coming up and my 71st solar eclipse including the annulus and partials.

[Mat Kaplan]: Did you tell me once that you don't like being called an eclipse chaser?

[Jay Pasachoff]: Well, the eclipse is go with thousands of miles across the Earth. So I'm an eclipse preceeder, and some people might say an eclipse enthusiastic. And my friend Glenn Schneider from University of Arizona has used the word umbraphile.

[Mat Kaplan]: Oh, I like that.

[Jay Pasachoff]: So, I do like that. There are some people who object to putting a Latin root together with a Greek root, but it's as an umbraphile we've worked together on several things and I've sent him a lens to take on the eclipse flight that he has been navigating for out of Easter Island and they are able to keep up with [00:26:00] this with this totality for more than eight minutes, which is probably going to be the longest ever for an eclipse aside from that one Concorde flight.

[Mat Kaplan]: I remember reading about that, didn't they put a window in the fuselage of a Concord?

[Jay Pasachoff]: Well, it's a problem. It was a problem because well also if you want to be competitive is as I am did the people who were on that flight for for 70 minutes actually see the eclipse or were they just locked up in this... in this tube in the this metal tube with a with a few glances out if they could look through some instrument for a short time, which is basically what happened.

[Mat Kaplan]: I see.

[Jay Pasachoff]: But for that eclipse to be the 7-minute long eclipse on the ground that that it was the sun had to be high in the sky that had to be almost noon. So there are no windows there. They had to take this model Concord, this experimental model Concord, [00:27:00] which was fortunately going to be retired and they they did put some quartz windows right in right in the top and some instruments looked looked out that and it flew from off the coast of Africa and landed in Chad and I did I did hear that they didn't have enough fuel for a go round when they reached when they reach Chad, but the plane is actually now on display at Le Bourget airport in France in Paris, where there's an exhibit about that eclipse flight and there's an air and Air and Space Museum. One of my most successful eclipse events was at the eclipse of 1970 in in Mexico where I went to Indian village Mia what land south of Oaxaca with Professor Manzo and by that time I was a postdoctoral fellow no more just a freshman and we had some very elaborate equipment at that time and I've been contacted by some people from Oaxaca who are now on arranging a 50th anniversary exhibition of related things there [00:28:00] and we had a National Geographic article at that time and we got some very interesting observations and we did so well in that eclipse in 1970 that we decided to look ahead for the longest possible eclipse, which was this 1973 one that was going to be up to 7 minutes and 4 seconds long. But at that time there were not computer screens which you could press buttons. So I got a map from National Geographic and we pasted it on Professor Menzel's door and I got latitude and longitude and plotted a path and then I looked right in the middle to for the longest place and and I look for the nearest place to that and it said Timbuktu. I hadn't even known that Timbuktu was a real place at that time. Of course, it's a name that you use for things that are really too far away, which is also what Ultima Thule incidentally, I discovered was use it's a something been in use for a couple of thousand years for something in the in the Far Far North very appropriate. So anyway, so [00:29:00] Professor Menzel and I went to Timbuktu or we went to Agadez first in Niger, adjacent, and then we saw whether we could mount an expedition about an hour north of Agadez or an hour north of of Timbuktu. He actually didn't come on the second part of the trip and we decided that we actually couldn't manage all the equipment. We needed it seven minutes and four seconds. So he went to Mauritania where there was 6 minutes and I think 20 seconds and I went with the National Science Foundation team to Kenya where we had over five minutes. But a better chance of clearer skies, and that was a major effort with a coordinated push by the US National Science Foundation.

[Mat Kaplan]: So August 21st, 2017. I know where I was I was in Carbondale, Illinois at Southern Illinois University in front of 16,000 people looking up at the only cloud in the sky that blocked most of totality. [00:30:00] Where were you and since this was obviously much more accessible than Timbuktu for an observation like that not just where were you but what do you bring with you?

[Jay Pasachoff]: Well, first of all, I rely on my friend and colleague Jay Anderson, Canadian retired meteorologist who who looks at 20 years of statistics of cloudiness from from satellites, and he and I are actually redoing the Peterson Field Guide to the Atmosphere. Hmm, and now for the for Houghton Mifflin.

[Mat Kaplan]: Another series of books that you've also have done.

[Jay Pasachoff]: Done the Peterson Field Guide to the Stars and Planets which occurs I took over from Professor Menzel who did the first edition. This is now the fourth edition and and this new 16 printing has some images from the eclipse in Illinois and in Aragon, but in any case the best weather seemed to be clearest predictions seem to be for [00:31:00] Oregon and we looked around to see where to go and I noticed that there was a city in Oregon called Salem that I didn't know anything about that was right in the path. And then I wrote the professor of astronomy there who was very hospitable. He said come take a look and and then I saw that somebody I knew from graduate school had actually given a talk there recently and it turned that he would Frank Bashi from Texas. He was an alumnus then I discovered that the President of Willamette University is in fact a pulsar astronomer, Steve Thirsted, so they were very hospitable and I went out there and we went and looked around and we decided we could observe from the balcony outside the math and computer science building where we would have some security we would have some internet and some electricity and in fact later that day I got an email from Glenn Schneider, my friend and colleague who [00:32:00] said I was looking on Google Earth and looks like there's a balcony that you might go take a look at. So even Google Earth that turned out to be the spot and and in any case we had a big group there. I now travel often with a travel group of tourists in addition to my scientific team and my students. And so we had a lot of arrangements there. I like to be able to sleep in the zone of totality so we don't have to worry about traffic and getting there on the morning of the eclipse.

[Mat Kaplan]: Which was a problem in Illinois.I can tell you.

[Jay Pasachoff]: Well and and so we could walk over to our site one of my colleagues at Williams College who worked with us on a planetarium drove a truck across the country for us with a with a lot of our equipment. So it was easy to get the equipment there than it is for chile, but we actually have shipped equipment this week from Williams College to my colleague David Zelinsky in Philadelphia who is transshipping [00:33:00] to the Kitt Peak National Observatory in Arizona because they will be packaging it with other equipment that goes to Chile getting it through customs for for us to go to the Cerro Tololo Inter-American Observatory. So we're already organized for the for the equipment there, but in 2017 we were able to just take a truck with a lot of telescopes and cameras and tracking mounts.

[Mat Kaplan]: You've been doing this for so long. Is it as exciting as thrilling as as the first one that you saw all those years ago?

[Jay Pasachoff]: Oh it gets more exciting now, they're just so fabulous and I keep trying to explain to people how beautiful they are and how important it is to get in the zone of totality.

[Mat Kaplan]: Yeah, you're not alone.

[Jay Pasachoff]: So one of the examples I've given is imagine you go down to Yankee Stadium, after all I'm from the Bronx, and you go down and you buy a ticket and then you go home and somebody says where've you been? And you say, I went to Yankee Stadium. Well, that's correct statement, but you missed the [00:34:00] game. So to go to a partial eclipse is like going to the ticket booth, but not seeing the game. And then last month I was at the National Museum of American History in Washington DC and you know what they have there. They have a 1920s ticket booth from Yankee Stadium.

[Mat Kaplan]: How appropriate. I can tell you that one of our parting gifts for our now Executive Director Emeritus, Lou Friedman, were a couple of seats from Yankee Stadium when when he retired from his his job here at the Society.

[Jay Pasachoff]: Yes, Lou and I have reminisced together.

[Mat Kaplan]: So fellow Yankees fan, let me turn away from eclipses for a bit, though not too far away. Where does astronomy stand among the sciences?

[Jay Pasachoff]: There's an old joke when you're on a plane and you don't know if you want to talk to the person next to you on the plane for the six or 10 hour flight. And if you want to talk you say you're an astronomer and if you want to have quiet and no questions, you say you're an [00:35:00] astrophysicist. So astronomy, very justifiably has a wonderful place in the public image. I don't have to tell you here at the Planetary Society about that, but the people are very interested in not only the planets but also the the universe beyond and the things that have just been found over the last few years not to mention the decades before, the century before, have just been fabulously interesting and continue to be interesting with the new planetary launches and Mars and another Mars launch next year. From, well several from different countries.

[Mat Kaplan]: Yes.

[Jay Pasachoff]: Well all this LIGO stuff and neutron stars and not to mention the black holes merging there's just stuff across the board and this week has been the hundredth anniversary of the eclipse that took place on May 29 [00:36:00] 1919. It was not long after World War 1 and during the war this strange German scientist Albert Einstein had an idea that that advanced his earlier special theory of relativity that didn't include gravity and he worked on an idea that did include gravity, a general theory of relativity. There was one young German scientist Erwin Finlay-Freundlich who went in 1914 to Crimea to try to observe it and just as he got to the Russian border World War 1 broke out and he was interned in his equipment was seized and they didn't observe that eclipse in 1914, which was a good thing in the history of Science and the philosophy of science because Einstein didn't yet have his final idea for what had to be in his theory, and when he kept working on it a couple of years later he actually doubled the prediction and there's a very nice letter between [00:37:00] Einstein and George Ellery Hale here in Pasadena asking Hale if they could test this at at an eclipse and the idea is that when Starlight comes near the sun if it's near enough, it would be warped. It would be deflected by the warping space caused by the mass of the Sun and then when you're looking back on your line of sight the Stars would appear to be slightly deflected. And in 1919 there was an eclipse with the sun in the hyades a star cluster so there'll be a number of stars to test this on if they could get these good observations and Arthur Eddington an English scientist worked on this especially and he ran an expedition to the island of Príncipe which is now in the country São Tomé and Príncipe's off what's now Gabon where we were for an eclipse in 2013 and a second [00:38:00] team led by another English scientist Cromelin went to Brazil. The Astronomer Royal Frank Dyson was the one who really coordinated the reduction of data when when it was all over. When the results were released in November 1919 at a joint meeting of the Royal Society and the Royal Astronomical Society, it confirmed Einsteins results and Einstein became famous the world over with headlines and papers all over the world. Now in recent years, there's been some doubts raised as to whether Eddington fudge the results a bit than choosing which cameras to use or not because one of the cameras was out of focus for example, and do use those results or not. But this is now been carefully looked at including in a new book by Dan Kennefict. And the result comes out fine, and Dyson was really in charge not Eddington, and Dyson was opposed more than favored. But but the result really does back Einstein and has [00:39:00] since 1919.

[Mat Kaplan]: And there have been endless tests of general theory of relativity since then, Albert stands up pretty well through all of these and of course now the detection of gravity waves. It really does make for quite a history. Do you think you could make the argument that astronomy may have been the first science we may not have thought of it as science when our hominid precursors here those who preceded us were looking up at the stars, but certainly they were fascinated by the sky.

[Jay Pasachoff]: Oh, yes. Astronomy has been very important. And in fact to go back to my eclipse theme you get an image of what we call a pinhole camera, but that's just really any hole with something shining through and the Sun is round. So you don't notice that there's an image of the sun below a hole, but when the sun is partially eclipsed then you see the Crescent or the the dip out of the Sun. So the idea is a couple of thousand years ago [00:40:00] somebody noticed this imaging at an eclipse of the Sun and that eventually led to a pinhole camera and a camera obscura and of course led them to photography and and TV. So astronomy is at the basis of everything.

[Mat Kaplan]: You know, I never put those together that that series of developments but it makes perfect sense. Your love of astronomy history has led you and your wife to the collection of a pretty amazing personal library. Who are some of the astronomers whose works you've collected?

[Jay Pasachoff]: Well when I was in college, I was scared to go in the Widener Library at Harvard College, the open library, but when I started getting some royalties from my textbook I decided to see if I could get some books by the people who I mentioned the textbook. So those are going to be the main line astronomers like Galileo and Copernicus, etc. So I asked the librarian of the rare book library at Williams College [00:41:00] if I wanted to buy a book by somebody like Galileo, what would I do, and he said well, we don't have any money but but Mr. Chapin, is it at the library used to buy books from somebody in New York. So I called that dealer and I said I wanted to buy a book by somebody like Galileo, what would I do? Their response was well, I have a book from Galileo here. Why did you come down to New York and see it?

[Mat Kaplan]: We're not talking about reprints here we're talking about original...

[Jay Pasachoff]: This is the 1632 book The Dialogo. Which got Galileo in his final trouble that got him into house arrest. And that's what got my book collection started. And then I had known at Harvard from from even my undergraduate years the astronomer Owen Gingerich who got interested in Copernicus's anniversary year in checking on Copernicus books and then eventually few years later I asked him if I wanted to get a Copernicus De Revolutionibus from [00:42:00] 1543. What would I what would I do and he looked around the world for the with his connections and and help me get Copernicus at that time. So I have a few dozen books, but they are from the major people, particularly fond of the books by Galileo and Kepler and of course the the Copernicus.

[Mat Kaplan]: So just as you were once afraid to go into the rare books collection, I would have the same fear if you had brought one of these with you, I wouldn't want to touch it. Not just because I would be afraid that it would dissolve under my fingers and you'd never forgive me, but because of what that represents in the history of civilization.

[Jay Pasachoff]: Well, one of the nice things about being at Williams College as we really are centered at our students and I did now twice give a rare books course with a dozen students in in the room and we pulled out a bunch of these original things each each of the dozen sessions each semester. So the students really do get to [00:43:00] play around with with the books. These are pretty sturdy books. They had much better quality paper back then then we then we have now so there you can touch them, I invite you to come and see us at Williamstown. I'd be glad to show you some books.

[Mat Kaplan]: Oh I will take you up on that someday. I'm going to come forward several hundred years now. I loved Walt Whitman, but that's in spite of him writing the poem called When I Heard The Learn'd Astronomer, I'm sure you're familiar with the poem.

[Jay Pasachoff]: Well, there are two things wrong with Whitman one is he's from Brooklyn and I'm from the Bronx. So there right away. There's a problem there. But but I actually wrote somewhere a response to that poem. I very much objected to When I Heard The Learn'd Astronomer because he makes the point from his point of view that all the calculations take away from the enjoyment of this guy and for me and many people like me knowing in more detail [00:44:00] what the what the sky is like really adds enjoyment. So there's there there's a repast to to Whitman's to Whitman's poem.

[Mat Kaplan]: The analogy that I always draw and this is taking us in a direction that I was hoping to go is that if you go into an art gallery famous art museum the National Gallery, or wherever, the Huntington here in town where you're headed after our conversation. Don't you get a lot more out of that art when you know about the life of the artist and you have someone who has studied that work talk to you about the composition and what this object might have meant to the artist. Isn't it the same with science?

[Jay Pasachoff]: I certainly think so and I like to learn more about the details of what the paints are, what the background is. My wife and I went to hear the pianist Lang Lang on Sunday play with the LA Philharmonic and we went to the the session before in which the principal [00:45:00] violist played on actually a viola that they brought from Germany that had been the orchestra that Beethoven used but we learn something about the the pieces in the background so I certainly do think we benefit from these things. The Whitman poem is not the only poem I object to. There's this annoying poem twinkle twinkle little star how I wonder what you are, and but but so I've got a version Twinkle Twinkle Little Star now, we know just what you are. And and then some other people have written alternative versions also, so so that's a poem that could be updated, too.

[Mat Kaplan]: This is taking us in a direction I wanted to go and I did not know that you would be bringing this other book, which is not quite out yet. And I read a little bit about online Cosmos the Art and Science of the Universe by Jay Pasachoff and your collaborator on this one Roberta Olson. We were just looking through it a little bit before we started recording. This is an absolutely gorgeous [00:46:00] book and as listeners know, I love it when it's possible for us to bring science together with art on this program. Sure looks like that's what you were up to here.

[Jay Pasachoff]: I've now been working with Roberta Olson for quite a while. She is a professor emeritus of art history. She was at Wheaton College at the time and now she's at the New York Historical Society and we were brought together by Halley's Comet. She actually had been teaching art history and was talking about an image by Giotto of the Star of Bethlehem, and she noticed it had a tail. And so that was the discovery that it was Halley's Comet in the Giotto. And in fact the European Space Agency asked your permission I understand to name thier mission to Halley's Comet the Giotto.

[Mat Kaplan]: Oh, yes.

[Jay Pasachoff]: Yes, really her permission to give so in any case. I did know that she came to Williams College to give a lecture in 1985 just before the main part of Halley's Comet and we realized that we had [00:47:00] similar lectures except the last part of hers was art and last part of mine was science. So we work together all this time. We had a grants in the 90s from the Getty Foundation to work especially on comets in British art. And we had a grant from the National Endowment of the Humanities to go to Nuremberg to see The Originals of the Nurburgring Nicole and the drawings the so-called exemplars and we've written a number of papers and spoken at meetings over the years. And finally we decided it was time for our magnum opus. So we have 10 chapters on different astronomical topics, comets or meteors or sun or Moon, history of photography, galaxies. And so we were able to work with the this very nice publisher, Reaction Books. We have some 300-plus photographs and of art works mainly a few astronomical photographs, too, and we're really very pleased with the way it came out.

[Mat Kaplan]: I'll [00:48:00] say it again. It is absolutely gorgeous. I don't know whether it is more an art book or a science book and I guess that's a good thing.

[Jay Pasachoff]: Yes, yeah. That's good.

[Mat Kaplan]: Anyway, this is one. I mean I get a lot of books. I want this one. But I you said again this is the only copy in the country?

[Jay Pasachoff]: If I had more than one copy in the country I would give it to you.

[Mat Kaplan]: We'll see if we can get one later from your publisher who is the publisher of this one by the way?

[Jay Pasachoff]: It's called Reaction Books, which is a London publisher and it's distributed the United States by the University of Chicago Press.

[Mat Kaplan]: And Cambridge University Press is once again...

[Jay Pasachoff]: Yeah the textbook is Cambridge University Press. Just to have a URL that's easy to remember at I have a link to various books that I've done.

[Mat Kaplan]: You've received so many awards more than we have time to mention here. The last major one that least that I read about, maybe there's something else that wasn't documented, two years ago you receive the 2017 Richt Meyer Memorial Award from the American [00:49:00] Association of Physics Teachers. Quoting now, "for outstanding contributions to physics and effectively communicating those contributions to physics educators." You continue to serve and take leadership positions on all sorts of bodies within all of science working in formal and informal science education. Why have you devoted so much of your life to writing and other ways of sharing this love? I mean you could have just gone off and you know published a paper now and then about what you were learning about the Sun but you've done so much more.

[Jay Pasachoff]: This just a matter of doing what's been interesting. I've always been interested in communicating what we've been doing. In fact when I was a graduate student I spent time as a non-resident tutor at Kirkland House at Harvard College working with undergraduates. And as I recall, I was in fact called in at one time by the Director of the Observatory the chairman of the department at the time and [00:50:00] why wasn't I devoting a hundred of my time to my thesis. But I did write an article on the Sun for Volume 1, number one, issue number one, of Astronomy Magazine for example, and and then at one point the later chairman of the astronomy Department thought of me when there was a job at Williams College that that came up. So I've been very fortunate to be able to do what I have liked most to do and that's involved not only doing some research on astronomy, but also in talking to people about it and taking students with me on expeditions.

[Mat Kaplan]: Interesting that you have that in common with your former professor at Harvard, Carl Sagan, the both of you at one point or another got in a little bit of trouble for being a little distracted and going as they saw too far afield from your field. There's another astronomer you've mentioned a couple of times and because you have returned to Pasadena, I just want to get your thoughts about that pioneer who [00:51:00] also like to share what his love, George Ellery Hale who had such a huge role not just astronomy, but in this region.

[Jay Pasachoff]: Yes, Hale not only founded for a while it was called Hale Observatory, and now that the Mount Wilson part run with together with the Magellan telescope in South America is is it's not called by the name anymore. But Hale built a laboratory in Pasadena now called the Hale Solar Laboratory in the 1930s and did observations from there when he was no longer able to go up Matt Wilson.

[Mat Kaplan]: In his home, right?

[Jay Pasachoff]: Well, no, actually he lived elsewhere, I discovered. The current owners live on that property, but that house was built later. Hale actually lived elsewhere and and had this ;laboratory adjacent to the Huntington Library was at Huntington property how convinced Huntington to come here and Hale played a role in founding the National Academy of Sciences [00:52:00] based in Washington and the role in the international solar Union, which morphed into the international astronomical Union. So Hale was a big a big figure in doing that and his grandson Sam Hale is an old friend of mine is now the head of the Mount Wilson Association, which is bringing Mount Wilson to the public. In fact, my wife and I are going to a concert in the hundred inch dome in a in a couple of weeks and artist has put a set of prisms on the hundred fifty foot solar tower that puts a solar spectrum down to Pasadena and he can direct it to various places even quite further afield.

[Mat Kaplan]: No kidding. We're within sight of Mount Wilson,we'll have to see if we can do that here in the parking lot at the Planetary Society. You have given me a very good reason to make another pilgrimage up the hill here from the Planetary Society [00:53:00] to Mount Wilson one of my favorite spots on Earth. I am so glad though that you were able to come here to our headquarters, Jay. Thank you for doing this and may you enjoy many more years not only of astronomy but is a wonderful ambassador of science and astronomy.

[Jay Pasachoff]: Well, thank you very much. You're very kind and it's been my pleasure to know you for a while and to know the people at the Planetary Society and including Carl and Lou Friedman and other people who were involved, now Bill Nye, Bruce Murray earlier. It's just wonderful to have this this gospel of astronomy spread so widely and the Planetary Society is being very helpful in that.

[Mat Kaplan]: Amen to that. Thanks again, Jay. Time for What's Up on Planetary Radio. So we are back with the Chief Scientist of the Planetary Society, Dr. Bruce Betts. Welcome back.

[Bruce Betts]: Thank you, Mat, good to be back. How are you doing?

[Mat Kaplan]: Great, and I you [00:54:00] haven't heard it yet. But we had a good conversation with Jason Davis earlier in this week's show about the current status of LightSail and the difference between LightSail 1 and LightSail 2 so all good stuff as we lead up to that launch on, we hope, the 22nd.

[Bruce Betts]: Jason who? Just kidding.

[Mat Kaplan]: So What's Up?

[Bruce Betts]: It's Focus on Jupiter Week because Jupiter is at opposition. So it's on the opposite side of the Earth from the Sun. So it its closest point out that it varies hugely, but it's good time to see it. It also means that it's rising in the East around sunset and setting in the west around dawn. You can check it out looking like a super bright star in the east in the early evening. Saturn coming up couple hours later in the East looking yellowish, but let's focus on Jupiter this week, shall we?

[Mat Kaplan]: All right. I wish I could have focused on it. It's been so overcast here. [00:55:00] Almost every night that I've missed out, but, yeah.

[Bruce Betts]: Dammit man, would you fix those clouds?

[Mat Kaplan]: I cannot fix the clouds, Captain.

[Bruce Betts]: All right onto this week in space history. It was 1985 that the Soviet Vega 1 spacecraft released a lander and a balloon into Venus, so that was kind of crazy. Vega 2 joined it shortly thereafter.

[Mat Kaplan]: And I know that there are still people who want to send balloons back to Venus, right?

[Bruce Betts]: Oh, yeah. Oh, yeah. I think we're ready for random space fact, and I do have a celebrity intro for you.

[Jay Pasachoff]: Hi Bruce, this is Jay Pasachoff. What's this week's random space fact, please?

[Bruce Betts]: Excellent. Thank you, Jay. We're going to fly LightSail, I don't know if you heard about that. Oh wait. Yes, you did. It's a solar sail and people often get confused because we talk about solar sailing. They think we're sailing on the solar wind. We are not, we're sailing on light [00:56:00] pressure, the photons pushing into the sail, but let's talk about the solar wind shall we? Because it's kind of amazing. The solar wind reaches speeds of 250 to 750 kilometers per second. Per second. It's really Zippy. It's even faster than LightSail.

[Mat Kaplan]: For now.

[Bruce Betts]: For now. Well for LightSail 2 I'm pretty sure it's gonna win. So let's move on to the trivia contest. I asked you to name everyone who served as NASA administrator more than once. How'd we do, Mat?

[Mat Kaplan]: Doesn't take long to answer this one because as most people figured we've only had a couple of Administrators who serve twice. So see if this matches your research. They were Dr. James C. Fletcher who served from 1971 into 1977 and then again '86 to '89, so quite a separation there. [00:57:00] And Dr. Allan Lovelace, who served in 1977 and then again in 1981. Both of those times, Lovelace was serving as acting administrator while of course James Fletcher one of the better-known NASA administrators who was a full-fledged not acting but the real thing administrator.

[Bruce Betts]: There you go. That all sounds right. I call them Grovers. Obscure US Presidential reference.

[Mat Kaplan]: Oh interesting, Grover Cleveland.

[Bruce Betts]: There it is.

[Mat Kaplan]: I'm very happy to say that Matt Mintor, a first-time winner even though we've been hearing from him for years very much like last week's winner, Mel Powell, don't forget Mel. Matt you are going to be the happy winner who gets a 200 point account and a Planetary Society kick asteroid rubber asteroid this week. [00:58:00] Congratulations. And I said don't forget Mel because sure enough Mel in Sherman Oaks, he submitted this who knew NASA had such an accomplished drama department so many acting administrators.

[Bruce Betts]: Aaahhhhh.

[Mat Kaplan]: And then he added, sorry Dr. Betts for the groan you'll unleash if Mat reads this one.

[Bruce Betts]: That's my own personal permutation of a groan.

[Mat Kaplan]: We're ready for a new one.

[Bruce Betts]: Gonna bore down into LightSail spacecraft trivia. What is the name of the alloy that the LightSail spacecraft booms are made of? The booms that pull out the solar sail, they are made of a kind of a weird alloy or tell me what it what it's made of but I'm looking for the name primarily. Go to

[Mat Kaplan]: It's not unobtainium, I don't think, right?

[Bruce Betts]: Dang it. Now. I need a new question. [00:59:00]

[Mat Kaplan]: That would help them deploy because they have an antigravity property that James Cameron... ah, never mind. You have until the 12th. That would be June 12 at 8:00 a.m. Pacific time Wednesday the 12th to get us this answer and somebody is going to win, I can almost guarantee it, somebody is going to win a 200 point account, worth a couple hundred bucks on that nonprofit World Wide network of telescopes and we'll do a couple more of these but we're getting near the end here for a while, another chance to win yourself a Planetary Society rubber asteroid and let us also throw in from that library of books that we have. it's Chasing New Horizons, the terrific book about the mission of New Horizons by Alan Stern and David Grinspoon. I think they've just come out with the paperback version of it and they sent us one of those and that one can be yours if [01:00:00] you win the contest this week. That's it.

[Bruce Betts]: All right, everybody go out there, look up the night sky and think about all the photons bouncing off your head. Thank you and good night.

[Mat Kaplan]: Not doing me any good, I'm afraid. I don't feel any thrust and it's not growing any hair, so. Thank you. He'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 our starry-eyed members. MaryLiz Bender is our Associate Producer. Josh Doyle our theme which was arranged and performed by Pieter Schlosser. I'm Mat Kaplan. Ad Astra.