Planetary Radio: Space Exploration, Astronomy and Science - 100 Millions Solar Systems Like Our Own?

Episode Date: March 1, 2010

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100 million solar systems, like ours? This week on Planetary Radio. Hi everyone. Welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. We live in exciting times. Astronomers are beginning to learn what percentage of stars in the Milky Way galaxy may have planetary systems like our own. The formula is based

on a thesis written by my guest this week. We'll talk to Scott Gowdy about his work, which includes collaboration in a project called MicroFun. Bill Nye, the science and planetary guy, reports in from London, England, on the ceremony that presented physicist Stephen Hawking with the Cosmos Award. And a fully recovered Bruce Betts will show us highlights of the night sky, tell us what happened this week in space history, and shatter our microphones with another random space fact.

Turns out Bill Nye isn't our only correspondent who's on the road this week. Emily Lakdawalla is the Planetary Society's Science and Technology Coordinator. Lots of us keep up with the latest planetary science via her entries in the Society's blog at planetary.org. So this week we catch Emily at the airport on her cell phone. The connection could be better, but it's worth it because, Emily, you're on your way where? I'm on my way to Houston for the annual Lunar and Planetary Science Conference, which is something I've been attending almost every year since I was in grad school. It's a convention of geologists talking about the solid surfaces of other planets.

And maybe we can get a more extensive report from you next week. I'll shoot for that. Excellent. We know that you've got to get on a plane. Let's start talking about the latest and greatest in the Planetary Society blog, beginning with these spectacular images of Enceladus. That's right. These are from a November flyby of Enceladus by Cassini

when they got just absolutely astounding views of the plumes actually in flight from the dark side of the South Pole and just flying very high into the, I want to say the sky, but it's not sky, it's a vacuum. They're just absolutely incredible images. I actually had some of these pictures on my blog back in November when they were originally released as raw versions, but these are the processed calibrated versions from the imaging team, and they could not be more spectacular.

I should mention that anybody looking for these in the Planetary Society blog will find them in her February 23 entry. There is another 3D image of one of these little tiger stripes, I guess technically called a sulcus? A sulcus. Sulcus. The C is soft. Yeah, in 3D, these things really surprise you just how

steep and rugged the topography is. And Solidus is, from a distance, it's one of the smoothest moons of Saturn. But from up close, you have this incredibly steep canyon from which all of these plumes issue. It's a lot like Europa in that sense, where Europa is about the smoothest of Jupiter's moons. But up close, it's just seamed and fissured by all these fresh cracks. The reason we're able to see those images coming back from Cassini, it's all thanks to the Deep Space Network. And you had a piece about that recently. That's right. This is something I've been keeping my eye on. The Deep Space Network, I liken them to the bridges of our road systems. They're the sort of unsung, important infrastructure

without which we can't get data back from all of these spacecraft across the solar system. And we've not been making the investments that we need to make in the Deep Space Network to keep it running. The biggest problem is with these giant 70-meter dishes, there's only one of them at each of the three Deep Space Network stations, and they're all about 40 years old. And they just, they're getting more and more downtime as they age. They need to be replaced with phased arrays of multiple 34-meter dishes, and they just broke ground in Australia for the first of three new 34-meter dishes

that are going to help replace the functionality of the aging 70 meters. And new technology, too, with these new dishes. That's right. The most important new technology being this beam waveguide technology that allows them to send the radio signal down into an underground chamber where they can house all the electronics, rather than keeping them out in the weather up on top of the dish where they're much harder to service. Emily, we better let you go. I think they're calling you to climb on board an airplane. They certainly are. Thank you so much, Matt.

Emily is the science and technology coordinator for the Planetary Society and a contributing editor to Sky and Telescope magazine. Hey, hey, Bill Nye the Planetary Guy here. Last weekend, I had the great privilege to attend an event where Stephen Hawking spoke. This is the guy that has proven right his ideas about astrophysics and the relationship of quarks with black holes, with the expanding universe, with all that we seem to not quite know about unifying gravity, the weak atomic force, the strong atomic force, and electromagnetism. And this guy is there. This is the famous guy in the wheelchair who speaks with a voice synthesizer where every sentence is this enormous step in thought. We were all there, your board members and the officers of the Planetary Society,

because he was presented with the Cosmos Award, which is named after one of our founders, Dr. Carl Sagan. And Carl Sagan's wife and widow, Andrea, was there, spoke very, very well. And Martin Rees, who is the Astronomer Royal to the Royal Astronomical Society here in Britain, spoke eloquently about the conflict, the tension between human space exploration and robotic space exploration. His claim, robots are inherently cheaper and better at the job. Humans maybe shouldn't even go. But then other members of the board said, well, without humans, no one's the slightest bit concerned. Compare if a human were going to Mars with a robot going to Mars. The trouble is the price.

Since the Apollo missions happened in the Cold War, where the United States was trying to defeat the Soviet Union by getting to the moon first in this spiritual, national, philosophical way. We don't have that kind of funding anymore, so will we ever go out into space farther to asteroids, Lagrange points where the gravity is balanced, and then on to Mars with people? Well, we'll see. But my claim is we have to do that. Humans have to explore so we can answer these fundamental questions. Where did we come from?

And are we alone? And we were discussing all of this in the presence of Stephen Hawking. It was quite an evening at Cambridge in the United Kingdom. It was exciting. It was a marvelous evening. Thanks for supporting us. I've got to fly. Bill Nye, the Planetary Guy.

Astronomer B. Scott Gowdy is now an assistant professor at Ohio State University, but ten years ago he was a Ph.D. candidate who wondered how many solar systems in our galaxy look like the one we live in. The thesis he wrote on this topic is back in the news, thanks to additional work by Andrew Gould, a colleague of Scott's at OSU. Scott was in Washington, D.C. a couple of months ago to accept the Helen B. Warner Prize. The annual award goes to an American astronomer who has made a significant recent contribution to the field and who is no older than 35. By sheer coincidence, it was Scott's birthday when I called him via Skype. Scott, thank you very much for joining us on Planetary Radio. It's good to be here. My interest in doing this is based on a press

release that came out at the beginning of January when you were about to make a presentation at the AAS, the American Astronomical Society. Let's start, though, with this technique that you have been using, along with collaborators apparently around the world, for finding exoplanets. And it's all part of this project with this wonderful name. I love it because it's kind of whimsical. Microfun. That's right. It's a microlensing follow-up network.

Yeah, the method itself is a relative newcomer among exoplanet detection methods. We found about 10 planets with this method so far. It's based on a phenomenon that was originally predicted by Einstein, gravitational microlensing, although at the time when he first proposed it, he immediately discounted it and said it would never be observed. The basic idea is quite simple. We basically wait, we look at a star and we wait for another star to pass very close to our line of sight to that more distant star. The gravity of

that foreground star takes the light from that background star and it focuses it and bends it into our line of sight, thereby magnifying it. So the foreground star acts like a giant magnifying glass. And as it passes in front of the background star, it makes that background star brighten and then fade in a very characteristic way. Now, if that foreground star happens to have a planet, that planet will also act like a magnifying glass, albeit a weaker magnifying glass. And so it'll create a little bump on top of that microlensing event due to its host star. And that bump will be shorter duration. And it's that little bump that we look for that's

the signature of a planet. And the nice thing about this method is that these light rays pass in the outer regions of the planetary system, so in the separations around the distance of Jupiter from the sun or Saturn from the sun. So therefore, this method is sensitive to planets in those regions of the planetary system. So we're immediately sensitive to planets, giant planets like our own Jupiter and Saturn, Uranus and Neptune, whereas most of the other methods that are more well-known, like the Doppler method or the transit method, are intrinsically sensitive to planets that are very close to their parent star, and so quite dissimilar from the giant planets in our solar

system. Now, how do you know when a star is going to cross the path of another star, as seen from Earth? Have you plotted this out or calculated this, Or do you just kind of notice, gee, look at that, this one's occluding the other one? It's an excellent question. It's actually one of the things that makes this method quite difficult, although quite exciting. The probability of this happening is about one in a million. So you have to look at 100 million stars if you just want to get a few hundred of these kinds of microlensing events. So there are other collaborations like the OGLE and MOA collaboration that actually monitor 100 million stars towards the center of our galaxy every day looking for these characteristic changes in brightness. And then there's websites you can

go to that announce microlensing events. This particular star is now being microlensed by a foreground star. And you can go and you can look at that particular star in detail. So they do all the hard work for us. And then the Microfun collaboration, the Microlensing follow-up network that I'm a member of, we go and we go monitor those particular stars that are the most interesting and the most sensitive to planets and look for these little blips that are the signatures of those planets. And we found a number of planets that way already. There's something I just, I love about that, the cooperative nature of the astronomical community where they're saying, you know, take a look over here, something interesting is going to happen. Well, it gets even better than that, because

not only do we cooperate with these other professional astronomers, but because we don't have a very large budget in the Microfund collaboration, and actually we need telescopes that are available at any given time, since we can't predict when these lensing events are going to happen we actually cooperate a lot with amateur astronomers located throughout the throughout the southern hemisphere and these amateur astronomers are great because they have access to their own telescope in their own backyard they can use it whenever they want and so we call them up or email them and say hey you know this event looks quite interesting can you please try to get some data on it and they they'll go and they'll collect data, stay up all night, maybe to the detriment of their work the next day, and send us their data. And this data has been crucial

in enabling us to find planets. I had no idea the role of amateurs was so important in this. We love these stories about these crazy amateurs who are amateur only in name. Exactly. They're amateur only in name. Exactly. They're amateur only in the sense that they don't get paid for it. Yeah, exactly. Their dedication often surpasses that of professional astronomers. And even some of their instruments nowadays. Oh, they're amazing. I mean, these guys are quite impressive.

We actually have a yearly meeting with Microfun with the amateur astronomers. We just got back from one the end of January, and I'm continually amazed at their dedication and their skill set. Yeah, of course, we take advantage of them as well here within the Planetary Society and the search for near-Earth objects that we fund. But that's a topic for another day. We did say that this is a worldwide collaboration, and I guess you have these amateurs everywhere,

but there are also professional astronomers around the world? That's true. We have professional astronomers in WISE Observatory in Israel, in Chile, all over the world, South Africa. So how many planetary systems or how many exoplanets? You said about 10 so far? 10 have been discovered with this method, and the Microfinance collaboration has been involved with roughly two-thirds of those detections. And the fact that you find different kinds of systems than the two most popular methods that we've talked about on this program that you just mentioned, does this really sort of help fill out our knowledge of solar systems across the galaxy? Absolutely. By comparing these various methods, we can really get a better sense of what's going on in terms of planetary systems. One of the big surprises when the first

planets, giant planets, were found were that they were located very close to their parent stars. And naively, from our planet formation theories, we expected that all giant planets form in the outer regions of the planetary system, similar to where Jupiter and Saturn occur. So we had to figure out that what must happen is that some giant planets form out there but then migrate in closer to their parent stars, like retirees moving to California or Florida in order to get closer to the warm. But it remained an open question because these methods were not sensitive to more distant planets. What fraction of giant planets

actually migrate and what fraction of giant planets basically stay put where they were formed? And in fact, one of the results that I announced during my talk, first time that this has really been determined, is that we figured out the frequency of giant planets using microlensing, compared to that to the frequency of giant planets that are closer in, found by transits and radio velocity, and we find actually far more planets in the outer regions of planetary systems, indicating that, in fact, most systems, the giant planets basically stay put from where they're formed. I'll continue my conversation with astronomer Scott Gowdy in a minute. stay put from where they're from. I'll continue my conversation with astronomer Scott Gowdy in a minute.

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The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. Scott Gowdy is an assistant professor of astronomy at Ohio State University. He won the American Astronomical Society's Warner Prize in January. He's also part of the MicroFun collaboration, which is using gravitational microlensing to find exoplanets, worlds circling other stars. He told us just before the break that most of the really big exoplanets, like Jupiter and Saturn, seem to form and stay in the outer reaches of star systems, just like they have in our own system. of star systems, just like they have in our own system.

Is this good news for smaller planets, planets like ours that sometimes need those big planets farther out to sort of babysit them, take care of them? Well, so, you know, this is a good question. And it has been argued that, you know, in order to have sort of benign environmental conditions and not be constantly impacted by comets or whatever from the outer solar system that we need, Jupiter is the sort of big bully or the protector that will knock these things out of the solar system. I'd say that's a fairly controversial point, but it's something definitely that we'd want to keep in mind. It would be important to figure out how often there are giant planets in the outer parts of planetary systems because it may turn out to be important. But like I said, it's controversial. It's unclear right now. Now, in fact, this was largely the topic of this press release that I got prior to AAS in January. And it involves some work by your colleague there at OSU, Andrew Gould, who apparently had a

realization and he looked back to the PhD thesis that you wrote when you were in your mid-20s about 10 years ago. I guess it indicates that we're beginning to see enough systems that we can start to get an idea of how many solar systems out there kind of look like ours. That's exactly right. Andy Gould is the P.I. of the Microfun Collaboration, and we've been working on finding planets and characterizing them for many years now. And we knew that we were starting to get to the point where we might be able to actually figure out how common these planetary systems are. So not just find individual systems, but look at those events where we didn't find planets

and try to figure out what fraction of stars actually host planetary systems like our own. But we thought this was going to be a horrible job and it would be very, very complicated. Well, what Andy realized by looking back at my thesis was he noticed that, in fact, for every single event that we looked at, it was characterization of the kinds of planets we should find all looked exactly the same. In other words, there was a symmetry in the data that we hadn't recognized before. And by recognizing that and then just making a few simple assumptions, he was able to actually estimate the frequency of solar systems like our own. And he put a number on that? That's right.

So we've actually, a couple years ago, we announced the detection of a planetary system that looks remarkably like our own, or at least like our own Jupiter and Saturn. It's a half-solar mass star with a Jupiter mass planet located half the distance of Jupiter from the sun and a Saturn mass planet located roughly half the distance of Saturn from the sun. So it's a planetary system like our own, except scaled down by a factor of two. So at the time we called this a solar system analog, but we weren't able to figure out how common these were because we hadn't figured out how often we should have detected these if all stars had such systems. Well, we made that calculation a couple months ago with this realization. We figured out we could make this calculation. It turns out if every star

has a solar system like ours, in the sense of having giant planets in the outer regions of the planetary system, we should have found six such systems. We only found one. And so that gives us immediately a very rough estimate of one in six stars host planetary systems like our own. And I suppose the key term there is very rough because, as always, you need more data. That's true. So with just one system, we can't pin that down very clearly. But we can say with a fair amount of confidence that planetary systems like our own are neither very rare, nor are they likely to be in the majority. Let's say there are 10, 15% of the star systems in our galaxy that kind of look

like us. I don't think that's any reason to be depressed. No, I would say that's planetary systems like our own are fairly common. I mean, that's literally hundreds of millions of planetary systems like our own now you know we should be careful to to note that we're not actually sensitive to planets like our own in other words birth like planets located in the habitable zone where we can have liquid water we wouldn't detected those planets if they were there all we can say is that in the sense of having giant planets in the outer parts

of planetary systems of those kinds of stars are, you know, quite common in our galaxy. So what's the future for microfun and microlensing itself amid all of the other exciting things that are going on with the search for exoplanets? Yeah, it's, it's, things are moving very rapidly and, and there's very, all the various techniques are actually trying to vie for dominance. I actually think that the right way to look at it is that the various techniques are very complementary to each other. They can be sensitive to planets in different regions of parameter space. And if we really want to understand planetary formation and really habitability and what kind of solar systems might actually host life,

we really need to understand as much as we can and collect as much data from all these different techniques. Microfund continues to tool along. We have more planets that we found that we're waiting to announce. We found Ford just last year. We expect to find even more this coming year because of certain upgrades and various collaborations, instruments and telescopes. And we're looking towards the future. We're

looking towards a network of telescopes to do this, but even better, funded by the Koreans, and maybe ultimately a space mission, which would really allow us to measure planets with masses as low as a tenth that of Mars, with separations greater than twice the separation of Earth from the sun, and even planets that don't even have host stars, free-floating planets. Wow. This has been delightful. Scott, thank you so much for talking with us. And please pass along my congratulations to your colleague there, Andrew Gould, and everybody else who works with MicroFun.

I will definitely do that. Thank you very much. B. Scott Gowdy is an assistant professor of astronomy and the director of graduate studies at The Ohio State University. He was also the recipient in 2009 from the AAS, the American Astronomical Society, of the Helen B. Warner Prize for Astronomy, which goes to astronomers who are not ancient yet. Not yet. We're not ancient yet. Not yet. And he's joined us here on Planetary Radio, where we'll also be joined by Bruce Betts for our weekly look at the night sky, SON's microlensing. That's coming up in just a few moments.

As promised, time for What's Up with Bruce Betts, the Director of Projects for the Planetary Society. Joining us via Skype, it's not 3 o'clock in the morning. He sounds healthy. How are you doing? Well, I guess it's been kind of a pathetic last couple of weeks. It's been a tough couple of weeks for you, for sure. Yeah, but you sound good. You sound like you're back to your old self. None of that. None of that. Just a little residual. I'm good. And the night sky is good, Matt. Check out Mars in the evening sky. It keeps getting dimmer, but it still looks like one of the brightest stars up there in the sky, looking reddish in the east, already fairly high up after sunset. And if you look above it, you will see Castor and Pollux,

the two bright stars up there of Gemini. And the three of them, as March moves along, will start to line up. Very exciting. And then also check out Saturn, which is rising a little bit later in the, still in the early evening it's uh migrating towards its opposition opposite side of the earth on march 22nd so check it out in the east as well we move on to this week in space history this week 1979 voyager 1 flew past jupiter showed us all sorts of spectacular things we'll talk about one of the bodies that observed a little bit later in the program. Ooh, such a tease. Also, Apollo 9 flew this week, giving us the first independent flight of the funny-looking lunar module,

in this case an Earth orbit, testing it out. Ooh, I think I can do it. I think I can. I think I can. On to random space fact oh my you are back baby i don't think skype could quite handle it i i think it's swooned sorry i saturated uh in a second week in a row it seems appropriate to uh to do something in honor of the Winter Olympics. If you wanted to ski on Mars, well, first of all, you'd need some ice on a slope. So you could go

to the poles, but most people think, hey, Olympus Mons, if we could stick some ice on there, then you could ski. Turns out, despite being just monstrously tall, it is even more monstrously wide. It's like the size of the state of Arizona. Most of its slope, particularly over almost all the volcano except the caldera and then off at the flank slopes, is like two to five degrees. So really kind of lame skiing. Good for cross-country. Yeah, very much a smooth basaltic flow. So, yes, cross-country skiing on Olympus Mons, but not a lot of downhill. Although maybe over on the scarps in the caldera if you're particularly crazed.

All right, the Winter Olympics of 2124. Well, that's what we'll shoot for. We'll be held at Olympus Mons. Yeah. We move on to the trivia contest, and based upon my trip to Vienna to talk about near-Earth objects, I ask you what the

committee that was above the subcommittee that was above the action team that I was on, what does copious stand for? C-O-P-U-O-S in the vernacular of the United Nations? How did we do, Matt? A lot of people got this one.

Big response again this week, people after that T-shirt. I'm just going to tell you who the winner was. It was Matthew Richardson, a first-time winner, as far as I know, from Oberlin, Ohio. He let us know the COPUS stands for Committee on the Peaceful Uses of Outer Space. Matthew, you've won a Planetary Radio t-shirt. Excellent. And if people would like to win another one, I've got another question, oddly enough. Well, before you move on, let me tell you about some of the responses we got from other people.

Oh, please do. Ian Jackson didn't even try for the correct one. He just came up with Committee for the Pensioning of Unemployed and Old Satellites. You know, they deserve a nice pension. Torsten Zimmer, our resident smart aleck. He, I think, had some other terrific meanings for this potential acronym. You ready? Committee of Politicians Unaware of Science.

And this one, which I think we can all identify with, Cell Phone Operators, Please Use Other Seats. And this one, which I think we can all identify with, cell phone operators, please use other seats. Now you can move on. Those are good. Thank you. Now we've covered solar system skiing. What if you want to go ice skating? Well, first place, you know, other than the lack of atmosphere and the high radiation environment, that would come to mind for me would be Europa, covered in mostly water ice.

But how much room would we have? I know it's a silly question, but I needed some kind of lead-in to ask, what is the surface area of Europa compared to Earth? So fractionally or percentage-wise, what's the surface area of Europa compared to the total surface area of Earth? Go to planetary.org slash radio, find out how to enter, and figure out how to ice skate on Europa.

You have until Monday, March 8th at 2 p.m. Pacific time to get us that answer. Cool. Very cool. Cold. Cold. Very cold. 100 colvins. All right, everybody, go out there, look up at the night sky, and think about what winter Olympic sport you would most likely do. Thank you, and good night. Clearly curling for me. I still want to see those tractor trailers scooting down the ice

with a little broom in front of them. That image has really haunted me since we talked about it. Nice. Bruce Betts is the director of projects for the Planetary Society, and guess what? He joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and made possible in part by a grant from the Kenneth T. and Eileen L. Norris Foundation.

Keep looking up. Thank you.