Planetary Radio: Space Exploration, Astronomy and Science - Back to Saturn for Brand New Cassini Science

Episode Date: October 17, 2018

Our most frequent guest returns with exciting, just-published research enabled by the 20-year mission’s enormous success. Linda Spilker has served as Cassini Project Scientist for 8 years, and was Deputy Project Scientist for the previous 13.  You’ll also get the chance to win Bruce Betts’ great new intro to  astronomy book in this week’s space trivia contest. Learn more at: http://www.planetary.org/multimedia/planetary-radio/show/2018/1017-2018-linda-spilker-cassini-science.htmlLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

New wonders from Saturn, this week on Planetary Radio. Welcome. I'm Matt Kaplan of the Planetary Society, with more of the human adventure across our solar system and beyond. I'm back from a brief vacation with a treat for you. It's another wonderful conversation with Linda Spilker, project scientist for the great Cassini-Huygens mission. What? You thought the fun ended when the spacecraft plunged into Saturn's atmosphere just over a year ago? Wait till you hear the latest great science based on data gathered a billion miles from our home world.

And stick around for what's up. Bruce Betts has a very special prize for the winner of a new space trivia contest. Linda, welcome back. It is great to once again sit across from you here in the Planetary Society studio. Well, thank you, Matt. It's a pleasure to be here. And congratulations. You won an Emmy. Absolutely amazing. yes. Cassini won an Emmy in the Outstanding Original Interactive Program. And it was for the integrated interactive experience. We had two 360-degree cameras in the room during that final few hours leading up to the plunge. And that was part of it.

Social media. We had eyes on the solar system. So many ways that the public could participate. And we had some pretty impressive competitors, Google, Pixar, Disney, and Sony. And so we were just thrilled to go up. What an honor to accept that award. Clearly, I should have stayed at home last year and just enjoyed this coverage instead of being at Caltech and JPL.

I'm lying. I wouldn't have given that experience for the world. Or what we did, what was it, two days later, three days later, that wonderfully enthusiastic audience in Beckman Auditorium at Caltech. Thank you and your colleagues so much for being a part of that. I was almost in tears. It was so thrilling to be able to celebrate your mission that way. That's right. It really was a celebration of an incredible mission, getting science through to the very last moment. And a series of papers that have recently come out are talking about some of those findings flying through that gap between the rings and the planet. So it paid off. And we're going to get to those, but I'm going to save them because it's like one is more spectacular than the other.

But first, a little review. 20 years in space, 13 of them circling Saturn, almost 8 billion kilometers or about 5 billion miles if you choose, 294 orbits, almost half a million images, 27 nations involved in the mission, 4,000 papers, and counting. A lot more to come. Absolutely. I think that discoveries within the Cassini data will continue for years to come. We really just have skimmed the cream off the top of this firehose of data that came back. And so stay tuned. There's more to come. I want to look back at some of the—this isn't old science. This is still very recent science.

And what's really interesting is that the first thing I'm going to mention is based on images that the spacecraft captured in 2009. But, I mean, it's such great evidence of how even data from a few years ago is unveiling new science. And you probably figured out I'm talking about this paper that was published just last month, September of 2018, about dust storms, dust storms on Titan. It's incredible, Matt. Around equinox, it turns out that there appeared to be a lot of wind. And in the equatorial region around Titan, where we have these dunes, there are some data from the visual infrared mapping spectrometer showing what look like clouds of organic dust particles. And so they've done some

work on that. And so the dune region would be the place that you would expect to see this kind of dust storm. And it just took careful analysis and ruling out clouds, ground fog, other possibilities until they could come out with these brand new results. This crazy little world becomes more like our own planet, it seems, every day. Absolutely. Lakes and seas, river channels, clouds that rain methane, so many things that are very, very familiar. We could talk about a lot more of the science prior to these six papers that have just been released, but there's one more that I know we should talk about,

and that is that still mysterious hexagon above the North Pole, which apparently we know it really is well above the North Pole now. That hexagon is quite interesting. When Cassini first arrived, the hexagon was in darkness. It was summer at the South Pole. Then as the seasons changed, that part of the atmosphere heated up, and we could still see the hexagon in the images and lower down in the atmosphere. in the images and lower down in the atmosphere. But as the atmosphere heated up, starting in about 2014, the stratosphere, about several hundred kilometers higher, warmed up, and there was another hexagonal shape higher up in the atmosphere.

And so as the temperatures increased, we went towards summer, that hexagon got more and more apparent, and it matched. Its corners matched the hexagon below. So now the question is, are these two hexagons connected in some way or communicating in some way? And it's very puzzling because it's not obvious that you could have this connection from much lower in the atmosphere to this hexagon that's brand new, just observed higher in the atmosphere. It might have been there, but just too cold. It took the atmosphere heating up for the composite infrared spectrometer to actually see it. You may regret using that word communicating because you or I or maybe both of us

are going to get email from people saying, what do you mean they're communicating? They're alive? Well, no, but they certainly are fascinating phenomena. Absolutely. Maybe it's some kind of a wave process that connects those two hexagons. Maybe it's just one giant tube that's connected in some way. And so there are lots of puzzles still to solve in those data. I'm not going to mention it immediately, but this makes me think of at least one of these six papers, which as we speak, they are being published today, or actually the press release is coming out today,

that will talk about these six additional papers. They haven't quite been published yet. We can talk about them because this show is not going to be heard for a few days. And I want to get into those, and I'll take them in the order that I saw them in the press release that you shared with me, beginning with ring scientists that you are, some exciting stuff about stuff coming out of the ring, ring rain. It's just incredible, Matt. When we flew through this region, we didn't know what we'd find. So on that first orbit, we used the high-gain antenna as a shield to protect us from bigger ring particles in that region. And as we flew through, we used the radio and plasma wave antennas as our particle detectors,

any little particles that hit these antennas generate an electric current. And we'd seen that in the Enceladus plume, in the region closer to the F ring. And we fly through this region and nothing. We don't see any particle hits. And then as we look at other data, and that was great news for Cassini. That meant we were safe. We could fly the rest of our 22 orbits in whatever configuration we wanted to, to get the best science. And it turns out those grains are tiny, mostly nanograins, about the size of smoke particles.

And so for the first time, we could measure their composition. And that's where the ring grain comes in. The Cosmic Dust Analyzer, as we flew through this region, measured the particles. And they found that some particles in the equatorial region were probably going into the planet, and they were made of water and of silica. But further away from the equator, those particles had gotten charged up. They were spiraling along magnetic field lines

and going into Saturn's atmosphere. And that's the ring rain that we talk about, these tiny icy particles going in at different latitudes around Saturn,'s the ring rain that we talk about, these tiny icy particles going in at different latitudes around Saturn, creating the ring rain. But there's this other population that we've seen from other experiments that go directly into the atmosphere in the equatorial plane from the D-ring directly into Saturn. And also our ion and neutral mass spectrometer that usually measures gases. These particles hit so hard because we were going so fast, 75,000 miles per hour that they vaporized. And so the ion and neutral mass spectrometer could measure the vapor.

And they found not only water, but they found ammonia, carbon dioxide, methane, and a whole host of organics, carbon dioxide, methane, and a whole host of organics all the way out through the full range of the instrument out to the 100 atomic mass units up to about C6, six carbons in a chain. So just amazing to think there might be organics in the rings. Then part of the question is there's a ringlet in this D ring, this innermost ring, that had brightened several years earlier as though something had hit it, thrown up a bunch of dust, and that dust looked very bright. And so we wonder, was there some kind of interaction with material from whatever that impactor was? And perhaps we're seeing some of it. And just by looking at the various instruments, we sort of have the pieces of the puzzle. And we still are trying to fit those pieces together to come out with a picture of

what's happening in this very interesting region where no one had flown before. What's going on in this gap between the rings and Saturn? We could spend the rest of the conversation just talking about this stuff. I mean, first of all, was this expected? Was it predicted that if particles hit the spectrometer, they would vaporize and you'd be able to analyze them? We weren't sure exactly what would happen. In fact, going in, the ion and neutron mass spectrometer thought they would see hydrogen and helium, you know, the gases from Saturn. And so they weren't expecting this very rich spectrum of these other organic particles. In fact, we didn't think we would see organics that would be there in the first place. We thought that the ring particles that we'd seen further

out, that they would just sort of be going into Saturn and the smaller ones would be creating this ring rain along the field lines. So, so many of our assumptions turned out to be wrong. But of course, for scientists, that's great. There's nothing better than having to basically, okay, let's try and figure out what these new data are really telling us. Keith, part of what you said a moment ago is that you detected organics up to the limit of this spectrometer. And of course, we're talking about an instrument that was, what, put together, designed 25 years ago maybe, or maybe locked down 25 years ago. If you had, let's say, the kind of spectrometer that is soon going to be headed to Europa on the Europa Clipper, would you have been able to detect even more

complex, that is, heavier organics? That's very possible, Matt, because perhaps what we're seeing in this organic population are just fragments of bigger molecules that perhaps broke apart. And this instrument was really designed to look at the upper atmosphere of Titan primarily. And then once we found the plume on Enceladus, it was repurposed, both it and the cosmic dust analyzer, looked at the particles and the vapor in the plume. And now here's a chance to look at material in this gap. So it's possible. It's really intriguing. Oh, that's the word.

Yeah. Yeah. Great to go back and find out. That's just one of the six papers that's the word, yeah. Yeah, great to go back and find out. That's just one of the six papers that's about to be published. Next one, there is some kind of electrical connection between the planet and the rings? It looks like, yes, there's a current flowing between the inner edge of the D-ring and Saturn's atmosphere. And how this exactly is happening, that's still a work in progress. But that current was definitely detected by the magnetometer on Cassini. And it might play with

the spiraling particles on the field lines as well. So it's an interesting story and it's still evolving. There's an awful lot going on in that space, inside those rings. You found what sure sounds like a Van Allen belt, but one that's really close to the planet? Right, a radiation belt in that region, in that gap region. And that radiation belt has some connection to some of the ringlets in the D ring. We'd seen hints of a radiation belt from a distance at Saturn orbit insertion, but to fly through it multiple times and directly measure it was tremendously exciting. It's a very weak belt. Saturn's rings are very good at shielding out the radiation.

It's not like an environment like Jupiter. Those rings are really sort of radiation-free zone. But when you get into the gap, then you have this tiny radiation belt that's back again. When I saw that the tilt of Saturn's magnetic field has now been measured to an extraordinary degree of accuracy, the first thing I thought was, aha, are we close to answering that great mystery of how fast is this planet spinning? Well, it turns out that the magnetic field axis and the rotation axis of Saturn are almost perfectly aligned. I think it's something like 0.009 degrees is the difference. And it's so small that we really can't use the offset in the magnetic field

to get to the internal rotation rate for Saturn. If you look at Jupiter, we're very successful in using the magnetic field offset to get a measurement of its interior rotation rate, for instance. But the story isn't over yet. There are hints that there are waves in Saturn's rings that are created by the way Saturn is oscillating. And you can have sort of a seismology, a chronoseismology, if you will, creating a series of waves in the rings. And so scientists are looking at this. We saw the waves from a series of stellar occultations over the course of the mission. And so the rotation rate might actually come from these waves in the rings. As a ring scientist, I think that would be great.

That is great. And when you say the planet is oscillating, it's almost as if somebody had struck a bell? Right, and it's vibrating at different modes, different frequencies, creating these waves. The sun does the same kind of thing. Do you expect more news soon about this rotation rate? A group of scientists are working right now to pinpoint

and look at the waves taken together to see if they can come up with a number for the internal rotation rate. Because you perhaps might remember we used the Saturn kilometric radiation, we thought, from Voyager. We thought that provided the rotation rate for Saturn. But once Cassini got there, that rotation rate was so different. We knew that the source of the SKR wasn't the inside of Saturn. Instead, it appears to be coming from the auroral zones. And that's another one of the papers we actually flew through, this SKR region, because these orbits were in so close to Saturn. And it does indeed appear that they're coming from the auroral regions. And we knew that previously because we had a different

SKR rate in the northern hemisphere. I'm sorry, SKR is? It's Saturn Kilometric Radiation. Think of radio waves that are coming out from Saturn. And it was, I guess that last of the six papers is about the aurora because you flew over both poles repeatedly. That's right. Flew through those field lines that connect the auroral region and flew through them with Cassini. And before we'd been too far away, our orbits were really too big to actually directly sample this region, or at least not very often that we would do that. Here's a shot in the dark. It didn't occur to me until just now. But the Juno spacecraft, the Jupiter, is also, of course, flying over the

north and south poles of that planet. And I bet you're looking at their data too, probably talking to people on that team. How do the two planets compare? Yes, there is work going on, Matt, comparing Juno data to Cassini data. And that's really just now getting started. And we're finding similarities and also some very astonishing differences. There are some more papers that will be coming out in a few months in science, one about the gravity field of Saturn and the winds of Saturn, and those are turning out to be quite different from what Juno is seeing at Jupiter. And then there's another paper in more detail about the rings, the really

high-resolution data sets we got of the rings, and then the views of those tiny ring moons. So there's more to come. As we have been saying, not just last year when the mission ended, but I think all through these conversations we've had over many years, the flow of science is not going to stop. No, not at all, Matt. All of the data are now in the planetary data system and available for researchers, Cassini scientists, and researchers at universities throughout the world

to take a look and help us figure out just what's going on in the Saturn system. There were a couple of standout features, are a couple of standout features, on the Cassini website, part of the JPL website, that we will provide a link to on this week's episode page at planetary.org slash radio. One of them is 10 Ways Cassini Mattered. And we don't have to spend a lot of time on this, but I thought we'd go through it quickly if you don't mind. And number one, lots of firsts. Well, I think that's probably obvious. Right. I think some of the most significant findings of the mission will be the detection of this plume at Enceladus telling us about a global ocean underneath its

icy surface, a salty ocean, and with evidence of hydrothermal vents on the seafloor and possible habitat for life, you know, much like Jupiter's moon Europa. Then, of course, landing on the surface of Titan with the Huygens probe, giving you ground truth, and then using the Cassini spacecraft or the remainder of the mission, 127 close flybys of Titan to reveal its atmosphere, its surface, and such an intriguing world. And one of the new Frontiers missions, Dragonfly, would go back, and if selected, it would land on the surface of Titan and hop around and make measurements. You know, it's a quadcopter that would be flying around in Titan's atmosphere and following up on so many of the questions that Cassini left.

Final decision, of course, has not been made yet regarding Dragonfly and its competition. But without sounding too biased, there sure are a lot of us who are excited. And, you know, as in all cases, when you see these wonderful concepts for missions that have to compete against each other, we all here at the Planetary Society say, why not both? Absolutely. That would be great. Number two, understanding of worlds that could harbor life. I assume, again, we're talking about Enceladus, primarily. Primarily Enceladus, but Titan also has a liquid water ocean underneath its icy crust. And then, of course, there's the intriguing possibility, could you have life in the methane seas on Titan?

You know, what kind of life would it be to use liquid methane instead of liquid water? So basically some of these discoveries from Cassini have sort of changed our view, a paradigm shift, if you will, of where you might find life. And the answer might come there are several places within our own solar system that could perhaps harbor life. Liquid methane life, definitely not as we know it. And I know that there are people, I think of Chris McKay, the astrobiologist, who are actually trying to figure out how that chemistry might work. Right. Which chemical reactions would work? And it seems like they're just not as efficient. And this life, if it does exist, would be very slow moving in the very low cold temperatures at Titan.

We've got to find out. Three, Titan is Earth-like. Well, we kind of covered that. Right, with the lakes and seas, the river channels, the dunes, now the dust storms, you know, weather on Titan, changes with the seasons, just so many things just using methane instead of liquid water. Cassini was a time machine, which is kind of tied to number eight here, I think, our understanding of the solar system.

You know, why did going to Saturn help us learn more about our own past? Well, the rings are one example. Perhaps by understanding how the ring particles coalesce and come together, forming objects like propellers, we might understand more about the protoplanetary disk in our own solar system and perhaps for exoplanets. How do planets form from these planetesimals in the disk? And then there's some thought that maybe Titan is a lot like the early Earth. You think of Titan as the early Earth in deep freeze.

And by studying its chemistry and what's going on there, we might have clues for our planet as well. So just a lot of very interesting findings in the system. We have talked about, I think in every one of our conversations, that a long mission allowed for observation of not just weather, climate, but seasons since you were able to hang out there for 13 years. Right. To see almost two full Saturn seasons, so seasonal change on Saturn and Titan, but also temporal changes, looking for temporal changes in the rings, temporal and seasonal changes in the magnetosphere of the planet as well. So just be able to hang out and follow up on your new discoveries, that that's a very powerful thing to do as well. Enceladus, Titan, but all those other moons and each one of them unique, that's number six. Right. Each moon is its own unique world with its unique characteristics. Iapetus is a great example with a very dark side and a very bright side.

It turns out that that dark material is Phoebe dust coming from a distant moon coating that dark side. And then that ridge that makes Iapetus look like a walnut. Could that have been maybe Iapetus had a ring, and maybe the ring particles fell into the equator and created a very ancient ridge that's now just peppered with craters? Wow. And of course, Dione. There's hints that Dione might be active, but we just didn't happen to be at the right place at the right time to actually see a mission from Dione. But there are hints that maybe there's another world at Saturn that might be active. And Hyperion, which I mentioned only because its appearance

is so creepy. Right. It looks sort of like a sponge or something, you know, these- A wasp nest. Yeah, yeah. But the dark material in these little cups are crater-like features on Hyperion, and it's very irregularly shaped. Number seven, the complexity and dynamism. I couldn't come up with a better word for it. Of the rings, if that's not already obvious from what we've been talking about. So many of our ideas have changed about the rings from, say, the Voyager era, that no longer do we see the rings as individual particles floating around, but so many places these particles clump together, forming the larger objects we call propellers, creating self-gravity wakes and

waves in the rings. And just getting in close in those final orbits really allowed us to get a sense of how much of this clumping is going on throughout Saturn's rings. And then watching the motion of the propellers as they migrated in and out in this disk of particles, and how did that happen? Or the beautiful waves along the edges of some of the gaps that are created by the moons and the Enkei and the Keeler gaps. Just so many incredible things about the rings. Number eight, I mentioned our understanding of the solar system. So I'm going to go right on to number nine. These last two are particularly human in their value. Simply the Cassini was a staggering human achievement. Just an incredible mission that originally was slated to last four years in orbit around Saturn. And then just to have such a healthy spacecraft and a great set of

instruments that could explore so much. We had a very diverse, very broad set of instruments that allowed us to repurpose as needed, follow up on discoveries. And then I think a key aspect of the mission was the international collaboration. You know, NASA teaming with ESA and OSE to come up with this mission, provide scientists from around the world to work together as a team to answer so many questions about Saturn. I agree, really a staggering achievement. And OSE, the Italian Space Agency. Right. Finally, wondrous beauty, which I don't think has been lost on anybody I've ever spoken to on your team or anybody else who appreciated this mission.

Saturn and its moons and rings are just some times we caught incredibly beautiful images. And one of my favorites is actually a solar eclipse image where Saturn is covering up the sun. And you can actually see all of the rings of Saturn. And there's three planets in that picture as well to kind of give you a sense of the majesty of Saturn. And the E ring is glowing like a giant blue halo around Saturn and just so many other instances of beauty in the Saturn system. Do you have an idea of how many people worked on Cassini over the years? Well, probably within the Cassini teams themselves, there were several hundred scientists. But those scientists also had postdocs and graduate students and other affiliates that

worked on Cassini over the course of the mission. And then, of course, there's the Cassini team. But then as the mission progressed, many, many scientists outside the Cassini teams. In fact, early on we did a look about 2014 at the number of papers with Cassini scientists as first or second author and non-Cassini scientists. It was about 50-50. That's a lot of scientists from around the world that are part of other institutions that have been part of helping us unravel the mysteries posed by Cassini's data. And then who knows how many, maybe you know, engineers, clerical support, people who built the spacecraft. It's definitely in thousands and thousands.

I agree. And we basically are now taking all these scientists and engineers and now they're going out and working on other missions. So those little bits of their knowledge or their expertise from Cassini, they're now going out to other missions. I'll close with this. There was this other, I said there were two really charming features on the website, which people ought to take a look at. And the other one is this sort of rotating little tribute to some of the leaders of the mission and other participants, largely scientists, but not entirely. You see their images, you see something that they had to say about the mission, and also what people say about them. One was quite striking, and we should have talked about it at the time when she passed away, but that was Claudia Alexander, who I think you knew pretty well, didn't you?

Yes, I did. Yes, I did. She passed away, very sadly, before the end of the mission, a year before, I guess, or two years before. Right. Yeah, she had worked on the Rosetta mission as one of the project scientists there and also had worked on Cassini. And she was very dynamic and active and really were helping us promote getting our data out in a way that people could easily use and understand it and leading to user guides for some of the Cassini data. The science goes on. We humans may not, but the science and the exploration certainly go on. Yes, the science analysis, looking through the data, will, I think, go on for decades to come.

And I think I can say with confidence that there are more discoveries in the Cassini data. We just have to find them. Linda, I say it every time. You have been the most frequent guest on this program. We may not be talking quite as often now that the mission is, in quotation marks, over, but as you've amply demonstrated, it is not over, and so we will talk again. I think you're going to hold that record for a while. Thank you again for sharing all of this and coming down to the Society office today. Well, thank you, Matt. It's been a pleasure. Time again for What's Up

on Planetary Radio. The chief scientist of the Planetary Society is Dr. Bruce Betts. He is on the phone with me. If you heard our show last week, you heard him in Washington, D.C. We were trying to use his Nameless Hotel's terrible internet connection. Because we had to pre-record this one, because I'm going on vacation, I now have him on the phone. Hi, Bruce. Hi, Matt. Can you hear me? I can hear you, and it is so much better than what we had to go through last week. Let's truck

on into this because we have a very special—we don't have any prizes to award this week because we didn't have a new contest two weeks ago, but we have a really great prize that joins our fantastic prize package when we get to the new contest this week. Awesome. Let's go to up in the night sky, and let's start where I don't usually start. October 23rd, Uranus. That's right, Uranus is at opposition, so it's on the opposite side of the Earth from the Sun. That means it's marginally closer than it is other times during the year. It'll be rising around sunset, setting around sunrise. You'll want to look up a finder chart to look for it.

If you have a really dark sky, you might be able to see it with your eye. dark sky, you might be able to see it with your eye. If you pull out binoculars or a telescope, you probably can see it as a little blue star, a little blue-green dot. So it's a good time to go looking for Uranus. It also got much easier to see Mars in the south looking reddish and Saturn in the southwest in the early evening, and then in the early evening, Jupiter getting lower and lower, looking bright low in the west. We move on to this week in space history. It was two years ago that the trace gas orbiter of the European Space Agency went into orbit around Mars, joining a whole fleet of other spacecraft there and looking for trace gases, including groovy things like methane.

And now and then is able to sniff that out from orbit, which is pretty amazing. A little snuffling there. Snuffle. That's a good word. Isn't it? It's just a heartwarming word. I was going to try to snuffle random space fact, but I don't really know how to do that. No, I can't do it. I don't know.

That was a pretty good try, I think. No. Space. That's a little gross, but I might just go with that. Okay. So, as you know, the sun is huge, but the bright red star anteres in scorpius is super enormously gigantically impossible to imagine huge if we're aware the sun is in our solar system the outer parts of anteres would extend out beyond the orbit of mars good lord

goes down mars that is That is one big star. God, that's a bigger star than Lady Gaga. Glad you're taking a vacation. Yeah, I guess it's time. Okay, well, like we said, no contest to answer. So I suppose we can go straight on to a new one. We're going to talk a little bit about things you can observe the night sky with. So on a typical pair of binoculars, what do the two numbers mean? For example, 10 by 50 binoculars, what do the numbers mean? Go to planetary.org slash radio

contest and get us your answer. You know, I just read a book that actually explains that and does it so that you understand how to use binoculars to look for stuff like Uranus and other cool stuff in the sky. I can't remember the name of the book, though. Can you help me? Why, yes, I can, Matt. The book is called Astronomy for Kids, How to Explore Outer Space with Binoculars, a Telescope, or Just Your Eyes. It'll be so much easier for me to look up this book if you tell me who the author was. Bruce Betts, Ph.D. Okay, no more fooling around. It's a great new book that Bruce has just completed, and it's going on sale, I guess, as we speak.

Is the e-book version available? Yes. Well, no. Not quite, but you can go to Amazon and learn more. Pre-ordering is open. E-book will be out October 30th, and the books will ship November 13th. I look forward to getting the hard copy version of this. I read it as basically as a

PDF, you know, a preliminary version, pre-publication. It's a terrific book. I've read a lot of intro to astronomy books. This one is targeting, what would you say, young adults, kids, but it really is good for anybody, and it's just nicely done. It's beautifully designed, and it's very much in your voice, so I have no qualms at all recommending this book. Well, thank you, Matt. That means a lot to me. So let's offer a signed copy of the book to whoever wins this brand new contest, along with, of course, a Planetary Radio t-shirt, chopshopstore.com, where you can see the whole Planetary Society store,

and a 200-point itelescope.net account. And you can use that account to look for some of the stuff that maybe you can't see from where you are, but the stuff you'll read about in Bruce's book. Cool. And the signed copy, I sign it, right? I don't think they would care as much if I signed it. Maybe we'll both sign it. No, you'll just sign it. You'll sign it. You and Lady Gaga. I'm not sure we can totally fulfill on that part, but I suppose we could try.

All right, no promises, but Bruce for sure. And I think that means we're done. Oh, I never said. You have until the 24th, October 24th, at 8 a.m. Pacific time to answer this one and maybe win Bruce's book. Astronomy for Kids. All right, everybody. Go out there, look up the night sky, and think about alarm clocks and how annoying they are. Thank you, and good night. Getting up bright and early tomorrow, huh? Yeah, just staring at the alarm clock, dreading it.

Just ignore that jet lag. He's Bruce Betts, the chief scientist of the Planetary Society, who joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its Saturnian members. Mary Liz Bender is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser. I'm Matt Kaplan, Ad Astra.