Planetary Radio: Space Exploration, Astronomy and Science - Planetary Radio 5th Anniversary Show: Astronomer Geoff Marcy on Discovery of Fifth Planet in Star System

Episode Date: November 26, 2007

We celebrate our 5th anniversary by learning about discovery of a five-planet star system, the largest found so far. Q&A on Jupiter's red spot.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Five years and five planets, this week on Planetary Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier, and we've been doing just that for five years. I'm Matt Kaplan. We're just minutes away from announcing the winners of our fifth anniversary contest, including the lucky listener who will own a little chunk of Mars. First, though, we'll talk again with Jeff Marcy, leader of the team that has just found a fifth planet

circling a star barely 40 light-years away. It's the biggest planetary system yet discovered, other than our own, of course. Emily Lakdawalla is seeing red and wondering why. And along with helping me announce our big winners, Bruce Betts will be here to tell us about the night sky. Everyone seems to be taking snapshots of our blue marble of a planet. Now it's Rosetta, the European probe that is headed for a comet. The spacecraft swung by Earth a couple of weeks ago.

You can see the pretty pictures at planetary.org. Speaking of pretty pictures, check out Stars Above, Earth Below, Tyler Nordgren's visual journey of astronomy and space exploration in America's national parks, also at planetary.org. It's off to Jupiter now with Emily. I'll be right back with astronomer and exoplanet discoverer, Jeff Marcy. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked,

What makes Jupiter's Great Red Spot red? Despite the fact that astronomers have seen a red spot on Jupiter for almost 400 years, we don't yet know what's responsible for its color. The Great Red Spot is an anticyclonic storm rotating counterclockwise in the southern hemisphere. Infrared measurements tell us that its clouds are cooler than clouds in neighboring areas, which means its clouds probably stand higher in the atmosphere, so it's probably a place where gases are welling upward from below. The current best explanation for the red color is related to this upwelling.

The idea is that the upwelling air carries with it phosphorus-containing compounds from deeper in the atmosphere. When these compounds reach the high altitudes at the top of the Great Red Spot, they are exposed to ultraviolet radiation from the sun, which alters their chemistry, creating new red-colored phosphorus compounds. Whatever explanation scientists come up with for the red color also has to explain why the color of the Great Red Spot changes over time. Stay tuned to Planetary Radio to find out more. Jeff Marcy of UC Berkeley heads the California and Carnegie Planet Search Team,

Jeff Marcy of UC Berkeley heads the California and Carnegie Planet Search Team, discoverers of more than half the 250 or so exoplanets that have been found so far. The team has just announced that five of those worlds circle one star that is just over 40 light-years from our own system. And they think there may be more children in 55 Cancri's family waiting only for the introduction of instruments that are powerful enough and analysis that is careful enough to find them. When I got Jeff on the phone a few days ago, he was preparing for yet another trip to Mauna Kea on Hawaii,

where the giant twin Keck telescopes are helping to prove that planets around stars are the rule rather than the exception. Jeff, congratulations. You know, we had to talk to you this week. Five years on the air, five planets in a star system. Well, it's been an exciting time, I guess, for both of us. Oh, yeah, I think so. I think you probably have more claim to excitement out of that number five.

Tell us about this system. Well, the star that is garnering so much attention is 55 Cancri. It's visible to the naked eye, if you have good eyes, binoculars, if not in the constellation Cancer. And what's remarkable about 55 Cancri is that it's a sun-like star, the same mass, age, chemical composition. And, of course, what's lovely about our own sun is that it has eight major planets. And what we've just learned is that 55 Cancri has five major planets around it. So it's the record holder for the most planets around any known star. And it's telling us that our own solar system is not an unusual beast, that there are many, many other systems out there in

the Milky Way galaxy with multiple planets. Your group has been studying this star and slowly finding planet after planet for what? Nearly two decades. Well, yeah. In fact, we started in 1987, my collaborator Paul Butler and I, with some sheepishness. At that time, no one had found any planets around other stars, and people thought it was impossible. And I think what's neat about 55 Cancri in particular is the first Doppler shift measurements that we made of this

star were made in 1989, some 18 years ago. And it turns out that the outermost planet takes 14 years to go around the star. So we were lucky to catch this star way back before people thought planet hunting was even possible because those early observations made it possible to detect the outermost planet that's just now completed one orbit. That's amazing. I had no idea there was at least evidence that was indicatory that far back. You know, back in high school when I decided not to be an astronomer, it was when I realized I would still have to learn math. That has a lot to do with how you're still finding these.

I mean, if you could give the standard one- or two-minute explanation of how we are finding planets that we can't see yet. It's actually an amazing thing. You know, even with the Hubble Space Telescope, you could stare at a nearby star, and any planets orbiting that star would be lost in the glare of the host star. So Hubble's actually not very helpful here. What we do instead is we watch the stars themselves, and they would normally be stationary. Big, massive objects like a star would just sit there. But if they're orbited by planets, the planet pulls gravitationally on the host star.

Indeed, our Earth pulls gravitationally on the Sun. And that causes stars, like the Sun, to wobble in space. They move around. And with the world's largest telescopes, we can watch the nearby stars, see them wobble. We actually measure their velocities by this so-called Doppler effect, just like sensing whether a train is a coming or going by the sound of the train whistle. We can tell whether a star is a coming or going from the light waves that are emitted by the star. And so we can determine the masses and the orbits of any planets that are orbiting those stars. determine the masses and the orbits of any planets that are orbiting those stars. But this ability to break down these little Doppler perturbations and say, gee, you know what, there's yet another planet here, I'm kind of blown away by the analysis that must

take. Well, you know, it is a little bit of math here, I have to admit, but it's very simple stuff. The idea is that if you watch a star and you see it wobble back and forth, back and forth, that's simply due to one planet that's orbiting that star, pulling it in a regular, repeatable way. But if instead you see the star wobble with a normal period, but there's another period superimposed on that first period, a little bit like one person moving a hula hoop around,

and that person with the hula hoop is actually sitting on a merry-go-round, you would see one circle superimposed on another circle. That's what we see in our stars, telling us there are two planets. And then if that isn't enough to explain the motion, we would then add a third circular motion to our computer model, and sooner or later we add enough planets to explain the full-fledged curlicue motion of the star. This technique, of course, favors big planets, and so far you've found in this system, what, moderately large to at least one very large planet.

Well, it's a remarkable system, 55 Cancri. The architecture is amazing. There's an outer giant planet, as you say, that's about four times the mass of our Jupiter. But then inward of that massive planet are four considerably smaller planets. In fact, they orbit quite close in, closer than the Earth is to the Sun. Indeed, the innermost is only 10 times the mass of our Earth. So what's lovely here is that we have a planetary system whose structure is similar to our own solar system. Of course, our solar system has Jupiter far out and four rocky terrestrial planets inward, Mercury, Venus, Earth, and Mars. And this new system around 55 Cancri has a giant planet

and four smaller planets inward, albeit all of them larger than the Earth. And one of those planets that's a bit closer is in what we're becoming to call the habitable zone. Yeah, there's this amazing region around all stars where the temperature isn't too hot or too cold, but instead just right for water to be in liquid form. And we think, that is to say, the biologists tell us that when you have water in liquid form, it serves as the solvent, the mixer of biochemical reactions, allowing amino acids and proteins to form, and eventually maybe something like DNA that replicates and codes for life generation after generation.

So what's very exciting is when you find a planet that could have liquid water, there's a chance that biology is also occurring on that planet. That's Berkeley astronomer and exoplanet hunter Jeff Marcy. He'll rejoin us in a minute. This is Planetary Radio. Hey, hey, Bill Nye the Science Guy here. I hope you're enjoying Planetary Radio. We put a lot of work into this show and all our other great Planetary Society projects.

I've been a member since the disco era. Now I'm the Society's Vice President. And you may well ask, why do we go to all this trouble? Simple. We believe in the PB&J, the passion, beauty, and joy of space exploration. You probably do too, or you wouldn't be listening. Of course, you can do more than just listen. You can become part of the action, helping us fly solar sails, Transcription by CastingWords org slash radio or by calling 1-800-9-WORLDS. Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed

Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. UC Berkeley professor of astronomy Jeff Marcy is telling us about the latest member of the family of planets discovered at star 55 Cancri. Don't be surprised if that family keeps growing. Your colleague Deborah Fisher at San Francisco State, part of this team that you lead, seems to think maybe some of the most exciting stuff in this system is yet to be found. It's in a gap where we simply aren't yet able to detect planets. Well, this is the thing about astronomy. Sometimes it's what you don't see that's more interesting than what you do.

And here's the case with 55 Cancri between that outermost fifth planet and then those four inner planets. There's this very large gap. It's something like the gap between Earth and Jupiter, but in this case, even larger. So you have to ask yourself, why don't we detect any planets at all in that giant gap between planet four and planet five? And of course, the answer might be that it's our own limited human technology. We simply can't detect at the present time Earth-like planets. So there could well be Marses and Venuses and even Earths in that gap that are lurking, just waiting for

the next generation of astronomers to come along and detect them. And how far off is that generation? I mean, you and your friendly competitors around the world seem to forever be pushing the envelope of what we can get our current technology to do. Well, what we're hoping to do, and we're already planning for it, in Northern California, we're building a brand new telescope designed specifically to detect Earth-like planets. We call it the Automated Planet Finder, APF, and we're building it at Lick Observatory. And if we can get a little bit more funding, we're really hoping to finish this thing, and we'll find Earths around nearby stars. And then to top all of that off, NASA, of course, is kicking in its own space-borne telescopes

that will have different capabilities, but those NASA space-borne telescopes are designed also to find Earth-like planets. So there's a real movement, a new subfield of science, in which we may begin for the first time to study Earths around other stars and compare them to our own Earth. So were you a betting man, and you had some of these new instruments to look into that gap at 55 Cancri? to look into that gap at 55 Cancri. How far off in years do you think we might be from finding a small, rocky planet in that habitable zone?

I suspect we're going to be finding something in that gap in the next few years. We will obviously observe this star, 55 Cancri, night after night using the world's largest telescopes. And if there's anything there rocky of a few Earth masses or less, we might be able to start picking it up, and we'll get early hints in the next few years. And it would be very exciting, you know, to sense another planetary system with an Earth reminding us of home. Oh, man, you think? My colleague Amir Alexander at the Planetary Society wrote a great article.

November 7th is when it was posted at Planetary dot org. And he mentions that actually a few years back, you suggested to your UC Berkeley colleague, Dan Wertheimer, that they start looking at 55 Cancri. Dan, of course, leader of the SETI at home crew. They couldn't find anything then, but let's say that you find that Earth-sized planet in the habitable zone out there. What would you want to see happen next? Well, this is the $60 million question. What we hope to do with this new telescope we're building now is to find a good population of other Earths, a handful of other Earths.

now is to find a good population of other Earths, a handful of other Earths. And of course, out of the 200 billion stars in our Milky Way galaxy, what direction should you point your radio telescope to try to pick up extraterrestrial signals? And the answer is, of course, point them at the stars that you know have Earths. So people like Dan Wertheimer will, of course, be avidly pointing their radio telescopes at the Earth-like planets out there, hoping to pick up signs of an advanced technology. And boy, would that be an exciting day to get the first hint that we are indeed not alone in the universe. that sadly, at least in my and probably your opinion, and a lot of our listeners, that those great radio instruments don't find anybody trying to talk to us. How far off might we be, I'd say considerably further, from being able to actually image one of these planets, Earth-like planets, and begin to say, you know what, there's water and oxygen circling that globe? Well, the greatest telescope ever conceived is being designed by NASA right now. In fact, there isn't funding for it at all due to budget pressures, but it's called the Terrestrial Planet Finder.

And this is a space-borne telescope that would be above the Earth's atmosphere, take pictures, that would be above the Earth's atmosphere, take pictures, as you say, of pale blue dots orbiting a yellow sun-like star, image it, and get a spectrum of the light from that planet, allowing us to assess how much oxygen and methane, maybe even signs of chlorophyll in this spectrum of light from that planet. And, of course, it would be just an extraordinary day for us to learn that there are other planets with actual signs of life on them. And I think this is unfortunately probably 20 years away, but it's not 50 years away. In the next two decades, we will have space-borne telescopes hunting for and hopefully detecting other Earth-like planets. So years ahead, pretty much as exciting as you and others have made the last 10 or 20. Well, it's been an extraordinary ride.

You know, if we think back 20 years, the only knowledge we had about planets or other stars came from watching Star Trek. And now we actually have real data. We know that our solar system is not unique. And for the first time, we're asking questions like, how will we detect life? And what do we do when we detect advanced civilization? So it's amazing the level of sophistication of our questions has risen enormously. Well, Jeff, search long and prosper. And are you off to Hawaii? As a matter of fact, in three days, I go again to use the world's largest telescope on the Big Island of Hawaii,

located high atop a hopefully dormant volcano called Mauna Kea. And we will be hunting for Earth-like planets every night. It's always a pleasure, Jeff. Congratulations once again. Thank you so much. Jeff Marcy leads the California and Carnegie Planet Search Team. He's a professor of astronomy at UC Berkeley, where he also directs the Center for Integrative Planetary Sciences. We will be right back to celebrate our fifth

anniversary and name those fifth anniversary prize winners. That's when Bruce Betts joins us for this week's edition of What's Up, right after a return visit by Emily. Return visit by Emily. I'm Emily Lakdawalla back with Q&A. It's a common misconception that Jupiter's great red spot has looked more or less the same for almost 400 years. But that's not true. A great red spot was first observed at Jupiter in the 17th century. But there were no recorded observations of a red spot through most of the 18th century. The present red spot has only been seen since about 1830, and like everything else

about Jupiter, the red spot is always changing. Pioneer 11's view of Jupiter showed a red spot two or three times larger and much more oval-shaped than the one we see today. Not only is the red spot smaller and rounder than it used to be, it's also much less red. Sometimes the spot is brick red. Sometimes, as now, it's pale salmon orange in color. Sometimes it's almost white. These changes can happen fast, within a few years or even less. And now the red spot has competition.

Recently, several medium-sized storms merged to form a new, bigger storm that has since turned red. The so-called Little Red Spot is now half the size of the Great Red Spot and still growing. It's possible that the two storms could merge one day. Or maybe the Great Red Spot will eat the Little Red Spot. Or perhaps the Little Red Spot will take the Great Red Spot's place as the largest storm on Jupiter. We'll only know if we keep watching. Got a question about the universe?

Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Time for What's Up on Planetary Radio. Bruce Betts, the director of projects, is here. This is the big one. Happy anniversary, Bruce. Happy anniversary, Matt. This is going to be fun.

Five years. Yes, five years and four big winners. Five, really, if you include the T-shirt winner this time around, the regular contest. Dive right in. Tell people about the night sky. Well, in the night sky we have still comet homes being comedy. Fuzzball-y. You can see it in the north, in the

northern hemisphere. It's in Perseus. You can check out a finder chart. It is near our friend, the star Murphak, as we have discussed in previous shows. And we'll again next week. Yes, with the trivia contest. And you can check it out with naked eye if you know where you're looking.

But I suggest pulling up some binoculars or a small telescope. Binoculars are great for it, and it will be very, very obvious in there. You'll see its coma, the dust and gas around it. And that will be lovely. You can also check out some nice meteors with the Geminid meteor shower, which is peaking on December 14th. On average, about 60 per hour from a dark site. And it's a good time.

Geminid's traditionally the best of the year. A little tough for the northern hemisphere, especially the colder climates. Don't always get clear weather and cold, but the most meteors on average during the year. Pre-dawn, you can check out Venus looking extremely bright in the east. Up above Venus is Saturn, and way up in the east up above venus is saturn and way up in the sky at that point is mars mars coming up in the evening you can check it out in the east coming up in the the early evening now coming to opposition december 24th and so that's our night sky roundup oh do you have more for us? Yeah, of course I have more. How many shows have we done?

Like 250? About that, yeah. Yeah, I have more. Okay. All right, we at least have to do Random Space Fact! With fifth anniversary joie de vivre. Exactly. I was feeling kind of laissez-faire. So I thought I'd throw it out there.

Random space fact, we're going to talk about the big guy, the big yellow guy, the sun, the surface temperature of the sun. It's hot. So depending on your degree system, it's kind of in the middle, around 9,000 Fahrenheit or more, around 6,000 Celsius Kelvin, ballpark. So that's the surface temperature of the sun. Kelvin ballpark. So that's the surface temperature of the sun. And when we come back for the trivia contest, we'll talk about other parts of the sun and their temperatures, because it's hot. And by the way, that temperature is why we see it as yellow. That whole fun blackbody radiation. Hotter stars bluish, cooler stars reddish. Alright,

now we can go to the trivia contest. Alright! We'll start with that boring but lovely Planetary Radio t-shirt. We asked you, what was the largest crater on Mars' moon Phobos? What or for whom was it named? How did we do? We did great. And so did the listeners. Of course, this was the last time that people were eligible.

By entering this contest, they were also eligible for the fifth anniversary. So huge turnout, gigantic turnout. Thank you, everyone who's participated over the last five weeks, and we hope you'll hang in there and keep going for a T-shirt. We got lots and lots of correct answers. Now, Michael Capps went above and beyond, because check this out. He actually sent a picture of Chloe Angeline Stickney-Hall. Dude, she is hot dude you are you're so right you're so immature but you're so right score so she was like the

the wife right of asaph uh hall and she was also like trey brilliant yeah yeah she was his geometry professor of all things. And, you know, they fell in love and the rest is history. That's true. So name for her, Stickney, the biggest creator on Phobos, almost so big the impact would have broken it apart. Stickney being her maiden name. Yep. And the actual winner this time around was Teril Prouty.

Teril Prouty of Sukhothai, Thailand, who says there's no astronomy in Thailand, only astrology, which apparently is not really true, at least in his case. So hang in there, Terrell. Bring astronomy to the masses there in Thailand, and you'll be able to do it much more easily wearing your Planetary Radio t-shirt. Cool. Okay, drum roll or fanfare, please. Yeah, that's good, but I'm going to find a real one, I think.

All right, all right, that'll do. All right, fine. Go ahead and insert a real one. So what are you going to do here? What are you going to do? I know we got our big prizes. Yeah, we've got four prizes in the fifth anniversary contest. This is the one people have been thrilled about.

And so you're going to start with the biggest one first. No, I'm going to start the other way around. What kind of, what sense of drama do you have? Sorry. And by the way, we had hundreds and hundreds of entries. And I only wish we had a Mars meteorite for every one of you. But we really, really don't. We have one.

That's right. Turns out we have one. All right. We're going to start with the Space Station Sim games. We have two of these from Vision Video Games. Thank you very much for that donation. Very fun, very cool. Very cool.

You played with it? I have. Yeah, you have been playing with it. I love the opening. Okay, our first winner, Betty Reagan. Betty Reagan of Socorro, New Mexico, is going to get a copy of Space Station Sim. Congratulations, Betty. Should we go right on? Roger Smith of Grand Rapids, Michigan.

Roger, you're going to get to build your own space station with Space Station Sim. I thought we'd do the Star Trek poster next. All right. Star Trek poster. Star Trek Remastered, courtesy of Mike Okuda, our good friend. And CBS, you know, that little company that runs a network or two. Oh, yeah. And Steve Proko. Steve Proko, if I'm pronouncing it correctly.

You're going to take home that Star Trek Remastered poster signed by Mike Okuda. And Steve, congratulations. He's from Davie, Florida. Okay. I'll be quiet for the official drum roll. Okay. Either that was two or three seconds of silence or I actually found one to stick in. Here it is, ladies and gentlemen, the grand prize winner. You just couldn't resist, could you? I couldn't. I'm sorry. From Plano, Texas, it's Mike Tate.

Mike, congratulations. You have won a fragment of a Mars meteorite, courtesy of SpaceFlory.com. Congratulations once again, and thanks to all of you for entering. Thank you very much, and thanks to those who donated our prizes. So happy anniversary, Matt. Happy anniversary. Back in the old days, when it was only the first anniversary, you actually let me have the interview thing, and I did that lovely, insightful interview with you. That was a million years ago, at least. That was a million years ago.

People can still find it in the archives, though, and learn all about Matt Kaplan. But right now I want to ask one question. Yes. What's your favorite flavor of ice cream? That's a tough one. It used to be fudge ripple. Now I'm not sure I could say. Difficult to say.

I'll work on that. All right. Ask another question. A trivia question. A trivia question. Matt trivia? No. That's trivial, no doubt.

Oh, okay. Well, I thought I'd ask, so I shouldn't have people researching your life? Okay. All right. Instead, we will ask you about the sun. We return to that. And to win a Planetary Radio t-shirt, which is more valuable than any piece of any planet out there,

answer the following question. What is the temperature at the center of the sun? And, of course, you know, it's theoretical, but we have good theoretical handles on it. So close to the estimates. And we'll put you in the hopper for random selection of the winner. And go to planetary.org slash radio to find out how to enter or to check our archives of those past wonderful shows, including insightful interviews by, well, you and, you know, once or twice me. But be sure to get that entry to us by Monday, December 3rd at 2 p.m. Pacific time. We're out of time.

Oh, all right. Everybody, go out there, look up the night sky, and think about pink newts. That one courtesy of my sons. Pink newts. Pink newts. Girl newts. They didn't specify. I leave that to the listener.

It's radio. He's Bruce Betts. Pink newts. Girl newts. They didn't specify. I leave that to the listener. It's radio. He's Bruce Betts. He's on the radio with us every week here with What's Up. He's the director of projects for the Planetary Society. I've got to say it one more time. Congratulations. Congratulations. Happy anniversary.

Oh, all of you who have made Planetary Radio the worldwide success that it is, and especially those of you who have told usary Radio the worldwide success that it is, and especially those of you who have told us that you enjoy the show almost as much as we enjoy bringing it to you, thank you, thank you, thank you. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great week. Thank you.