Planetary Radio: Space Exploration, Astronomy and Science - Hunting for Extrasolar Planets

Episode Date: May 31, 2004

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Let's go hunting for planets on Planetary Radio. Hi everyone, I'm Matt Kaplan. This time we visit with the most successful discoverer of worlds outside our own solar system. We'll join Jeff Marcy of UC Berkeley as he works with our world's largest telescope. Bruce Betts provides his regular update of what's up in the night sky along with the new trivia contest and we'll get started with Emily Laktawalla's Q&A about the first tourist to visit a mysterious place called Titan. I'll be right back. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, what will happen to

the Huygens probe if it lands in an ocean on Titan? It's not known for sure whether there are seas or oceans on Titan or not. The Huygens probe, built and operated by the European Space Agency, will spin away from the Cassini spacecraft on December 25, 2004, and, after free-falling for three weeks, will enter the dense, hazy atmosphere of Saturn's largest satellite. The probe's main mission is to spend two and a half hours parachuting down through

Titan's clouds, transmitting measurements of the atmosphere and of the approaching surface, whatever it may be made of. Huygens' signals will be transmitted to the Cassini spacecraft, which will relay them back to Earth. The data will include images captured constantly during Huygens' descent. But will Huygens survive hitting Titan's surface? Stay tuned to Planetary Radio to find out. If you go to the headlines section of the Planetary Society's homepage on the web, you'll find the first of what will be a series of articles about the hunt for extrasolar planets. This search only saw its first success 10 years ago, and already well over 100 other bodies circling other stars have been found. Most of those were discovered by a team working

under Jeff Marcy, professor of astronomy at UC Berkeley. When I spoke to him last week, Jeff was hard at work at the world's largest telescope using Doppler spectroscopy to add even more planets to his record. Jeff Marcy, welcome to Planetary Radio. Has it been a good night for planet hunting? It's been a spectacular night. It's 4 a.m. here at the Keck Telescope remote operations room, and we've observed about 80 stars hunting for planets around each one of them, and the night's been clear, and the stars are hardly twinkling.

They're just little tiny dots going right into our spectrometer. So it's just fantastic. Sounds like a beautiful night. You're on the slopes of Mauna Kea, somewhere below this amazing instrument? That's right. I'm in a town called Waimea in the foothills of the hopefully dormant volcano called Mauna Kea, where the telescope actually resides. We mentioned in our introduction that the Planetary Society on its website

is beginning a series of articles about the search for extrasolar planets, which, of course, we being the Planetary Society, we're pretty interested in. We could hardly do that, and we could hardly have gotten a better start to complement it on the radio than by talking to the guy who has discovered most of them. What's your total now, 70-plus? Well, we've discovered 75 planets around other stars so far, and in fact we have another eight that we're just about to announce. stars so far, and in fact, we have another eight that we're just about to announce.

I've just finished writing the paper, so it'll be up to sort of 82 or 83 by next week when we send the paper into the Astrophysical Journal. Congratulations. Thanks. Still living. What can you say? Discovering other worlds? I get paid on a commission basis per planet, you know, so I got to keep them coming. Well, please do. What are the results that you're getting there today? I mean, I don't imagine that

you look at these and while you're at the telescope facility can say, oh, look, there's another one. No, that's right. The planets that we're finding these days, the new discoveries, No, that's right. The planets that we're finding these days, the new discoveries, are planets that take a year, three or five years to go around the star. And we can't confirm the planet until the planet has gone around the star at least once, causing the star to wobble in response to the gravity of the planet. So it takes a while, and each time we go to the telescope, we get a little more information about the orbit, if any, of the planet going around the star. Now, there is an excellent explanation of your technique for discovering these planets in the article that is currently on the Planetary Society websites by my very talented colleague, Amir Alexander. But could you give sort of the

25-cent explanation of Doppler spectroscopy? Well, it's very easy how we find planets. As a planet orbits a star, that planet pulls gravitationally on the star, yanking the star around into a little circle, sort of like a dog on the end of a leash yanks its owner around, the stars get pulled around by their attendant planets. So we watch the stars and look for the so-called Doppler effect, which everybody's familiar with. When a train goes by, the train whistle changes its pitch as it's a coming and a-going, and similarly stars, as they wobble around due to their planets, change the pitch or frequency of the light waves. So that's what we're watching for is the change in the light waves

due to the planet yanking on the star. Now of these planets that you've found so far, 75 and 8 more are about to be announced, you said. Right. They have a lot in common, don't they? Well, the planets we're finding so far are large ones, the size of Jupiter

and Saturn. They're the only ones we can detect. Saturn and Jupiter being the two largest planets, of course, in our own solar system. And many of the planets we're finding are strange. Some of them orbit very close to the host star, others farther away. And many of the planets, this is the odd part, orbit in not circular motion around the star,

but elongated elliptical motion around the star. And that actually is one of the biggest puzzles is why it is, we don't really know, That actually is one of the biggest puzzles is why it is, we don't really know, why it is that most of the planets we're finding around other stars orbit in these elongated, stretched-out orbits. So these are not just the mild sort of ellipses that a planet like Earth goes around the sun in, but really stretched-out ones. Yeah. In fact, the comets in our own solar system go around the sun in these very elongated orbits. We all know that Halley's Comet only comes every 85 years or so, and that's because most of the time Halley's Comet is very far away, and then it dips down in close to the sun and the earth and then goes zooming back out again.

And that's sort of the kind of orbits we're finding for these extrasolar planets. And that's sort of the kind of orbits we're finding for these extrasolar planets. And indeed, therein lies the probable explanation for the wacko orbits that these planets are in. Probably these planets just got gravitationally yanked into these weird orbits, just as the comets did in our own solar system. I thought that most of the planets, these giants that have been discovered so far, have also been discovered fairly close into their stars, and that this maybe required a little revision of our theories about solar system formation?

I have to interrupt you at the moment. Sure. There's a little miniature problem. Yeah, HD 188015. We did that already, so we can skip it. Actually, what I'd like to do, Chuck, is go to HD 185144, back about six or seven on the list, and then we'll go back to our regularly scheduled stars. Now, I think that Jeff is talking to the actual telescope operator. We'll find out in a moment here.

185144 is the next star we should do. Yeah, we got it. We're about to move the Keck telescope to a famous star called Sigma Draconis. Sigma Draconis is easily visible to the naked eye, and it's one of the closest sun-like stars to us, and it's one of our primary planet-hunting stars. Have you observed that star before? We have.

We have seven or eight years of data on this star, and frankly, so far, no sign of a planet. But it's such a close star, thereby making it very exciting and interesting, that we continue to look. Maybe there's a Neptune or a small Saturn in there that has eluded our detection so far. By the way, who were you speaking to there? Well, I'm sitting here at the Keck 1 telescope remote operations room, and in front of me is a giant TV screen where I have video and audio communication

with the summit of Mauna Kea where the telescope operator resides. And so I'm talking to him, conferring about which star to move the telescope toward next, watching the quality of the data, the quality of the sky, and so on. So he's the one who really moves the telescope, and I'm just trying to keep the data flowing in from down below here. But for tonight, the Keck is pretty much yours. Yep, that's right. Hang on, I'm about to start a new exposure.

You know what, Jeff, let me... Starting, yes. We're going to take a break. This is a great time to do it, and we'll rejoin you in a couple of minutes. Sounds good. Our special guest, and isn't this interesting, radio, is Jeff Marcy, professor of astronomy at UC Berkeley. We're speaking to him as he sits on the slopes of Mauna Kea below the Keck telescope

that he's using as we speak, looking for evidence of extrasolar planets. Planetary Radio will be back right after this. This is Buzz Aldrin. When I walked on the moon, I knew it was just the beginning of humankind's Planetary Radio will be back right after this. We're tracking near-Earth asteroids and comets. We sponsor the search for life on other worlds. And we're building the first-ever solar sail. You can learn about these adventures and exciting new discoveries from space exploration in The Planetary Report. The Planetary Report is the Society's full-color magazine. It's just one of many member benefits. You can learn more by calling 1-877-PLANETS.

That's toll-free, 1-877-752-6387. And you can catch up on space exploration news and developments at our exciting and informative website, planetarysociety.org. The Planetary Society, exploring new worlds. And then way down at the bottom of the list, we'll finish off the night with Tau Ceti. That's HD 10700. There's one I know. Yeah.

And then the next one right below it, HD 11964A. And then the last star, HR 8781. We have only 45 minutes left in the night here. Oh, my. Okay. Well, don't left in the night here. Oh, my. Okay, well, don't let us interrupt at all. Oh, no, no, no. It's fine. It'll all go smoothly, I hope.

Well, we continue to eavesdrop on Jeff Marcy as he searches for extrasolar planets there at the Keck Telescope, the world's largest, or one of them, in Hawaii, the island, the big island of Hawaii. He has that telescope for the night. Jeff, thank you for letting us listen in, first of all. This really is exciting stuff. Well, it's my pleasure. We're having a lot of fun here ourselves. As you give these instructions to the actual telescope operator, he then reorients the telescope.

You look at that star, and I take it that what you're doing is getting these very accurate spectrographic analyses? That's right. We go star after star, spending about 10 minutes on each star. And when we point at one star, the starlight goes into the telescope. But then where your eyepiece would be, we remove the eyepiece and put a spectrometer instead. And so the starlight just passes on into this spectrometer,

which is just a fancy word meaning a prism that spreads out the light into all of its composite colors, blue, green, yellow, and red. So we store that spectrum of colors permanently on the computer. Is this a particularly sensitive spectrometer to detect these what must be fairly tiny Doppler changes in the color? Well, we're very lucky here at the Keck Telescope. We have basically the world's finest spectrometer. This machine at the back end of the telescope is about $10 million, the telescope itself

being $100 million. dollars, the telescope itself being $100 million. So we have both a great telescope and a great spectroscopic instrument with which to measure these tiny Doppler shifts that we have to measure to find the planets around stars. Before we took the break, I asked you a question. I want to come back to that now. And let me just summarize it. What have we learned already because of the discovery of these 100-plus and counting extrasolar planets that has changed our views about the formation of solar systems

and, for that matter, the presence of planets in the galaxy? Well, we've learned so many things, it's hard to know where to begin. But I would say the highlights are, first of all, we know there are many, many, many planets out there in our Milky Way galaxy. It contains 200 billion stars, and something like 10% of those 200 billion stars harbor planets. At least 10%. We can only see the Jupiters and Saturns. So it's anybody's guess as to how many of the smaller Earth-like planets are out there, but probably even more. So the basic reality is that our galaxy harbors billions, indeed tens of

billions of planets, many of which are undoubtedly small and rocky and may have a temperature that allows water to remain in liquid form, which is, of course, the essential ingredient for life. So you sound pretty confident that once we improve our instruments, once we're able to find them, we're going to find these ever-smaller planets until we start finding these new Earths. Yeah, I have no doubt about it. We haven't found any Earths yet, but all the theories and all the observations are pointing to more and more of the smaller planets that we can't quite detect yet. And because there's so many of them out there, I'm sure that there are the Earth-sized ones that have just the right temperature to support the kind of biology that we're used to. You have a great job.

Well, it's crazy. You know, I'm working all night here at the world's largest telescope. It's an incredible privilege. It's a joy. It's exciting. It's exhilarating. I've been up for 24 hours now. I got up at 7 a.m. Pacific time.

It's now 7 a.m. Pacific time again, and I haven't slept for 24 hours, and as you can tell, I'm having the time of my life. Yeah, you sound pretty coherent. Obviously, it's exciting, and you've had a lot of practice. Where do we go from here? We obviously do need, I mean, as great as this technique is, this Doppler spectroscopy that you and your team have had such wonderful results from, where do we go to fine-tune things so that we can find those small rocky planets?

There are three spectacularly wonderful new telescopes being built by NASA specifically to detect Earth-sized planets. And I'll tell you the names and a little bit about them because they're just so intriguing. The first one is called Kepler. It will launch in 2007, and it's a space-borne telescope NASA's building to try to find Earth-sized planets when they cross in front of a star, dimming the star by virtue of the Earth blocking the light from that star. So this telescope will look for stars winking, if you will, due to Earth's crossing in front. And then the next big telescope is called the Space Interferometry Mission

that NASA is building for launch in 2010. And that one is supposed to actually find Earths around the nearest stars by watching for the wobble of a star due to those Earths. the nearest stars by watching for the wobble of a star due to those Earths. And then the real spectacular, incredible machine that NASA is hoping to build in 2015 or 2017 is called the Terrestrial Planet Finder. And this machine should take the first pictures of Earth-sized planets, hoping to see a pale blue dot orbiting a star in the blackness of space. And it'll be a wonderful day when we get our first picture of another Earth orbiting a yellow, sun-like star.

I'm using the word exciting a lot, but I especially like your use of that term, pale blue dot. Well, it's, of course, reminiscent of our old friend Carl Sagan, who was the first one to talk about how glorious it would be to find another Earth and maybe life on that Earth. We have much to look forward to, obviously. In the meantime, though, you are using the best available instruments to continue this search, and I guess you're not going to be letting up anytime soon. Well, we're not. The first thing we're going to try to find are other Jupiters that are exactly like our own Jupiter. If we could find a star that had a Jupiter that

looked like ours, well, that's a pretty good signpost that perhaps there's an Earth there, too, that's a little bit like our own Earth. Jeff Marcy, we've only got about a minute left. I wonder if you want to direct anyone to any websites, which we will also put on the Planetary Society website, planetary.org,

where people can hear this program. Or any other parting thoughts? Well, my website that my team has developed is easy. It's www.exoplanets.org, e-x-o-planets.org. And I think the last thing to be said here is that we humans are remarkably lucky. We've crawled over the globe of the Earth starting on the East African savannah only 2 million years ago. Somehow we're reaching out into our galaxy to try to learn about the origin of planets and more interestingly, the origin of life.

to try to learn about the origin of planets and, more interestingly, the origin of life, oddly enough, to find out how it is that we crawled out of the East African savannah 2 million years ago. So we're learning about our own roots by reaching out to the stars. We look for other Earths to learn about our own and ourselves. A great way to finish. Jeff Marcy, we'll let you get back to hunting for planets and good hunting. Thank you very much. Jeff Marcy is professor'll let you get back to hunting for planets and good hunting. Thank you very much. Jeff Marcy is professor of astronomy at UC Berkeley. He and his team have discovered the majority of the extrasolar planets, the exoplanets, that have been found to date.

He is confident that we will be finding many others. And this has been a great way to kick off a new series of articles about the search for extrasolar planets on the Planetary Society website. Check it out there, planetary.org, and we will also have a link to Jeff's website, www.exoplanets.org. I'll be back

with Bruce Betts, What's Up?, and our latest trivia contest, right after this return visit from Emily. I'm Emily Lakdawalla, back with Q&A. After her two-and-a-half-hour descent, Huygens may survive landing on the surface of Titan, but there are no guarantees. If Huygens doesn't find an ocean and lands on a hard surface, she may not survive the fall, and even if she does, she could tip over into a direction so that her antenna is no longer pointing to the Cassini spacecraft. If she's lucky enough to

encounter the theorized seas, she is designed to float. Huygens is designed to report how hard the surface is by telling how much deceleration she feels when she hits. If the surface is liquid, there are sensors that can measure all of the liquid's physical qualities, the density, temperature, refractive index, thermal conductivity, heat capacity, and electrical permittivity. A tilt sensor will report any motion due to waves. And an acoustic sounder will measure the speed of sound in the liquid and possibly even its depth. Huygens could transmit data for half an hour or more after a soft landing. 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 this edition of Planetary Radio. We haven't done this by phone in a while. It seemed like a good idea this time because Bruce Betts has been a little bit under the weather. Are you feeling better? I am. I'm glad to hear it.

He is the director of projects for the Planetary Society, and he's going to tell us what's up. Well, let's start with what's not up or what's going away, which is Venus, which we've bonded with for so many months now. Really tough to see if at all in the twilight after sunsets. But this leads to the Venus transit of the sun, which will occur on June 8th and has not happened for well over 100 years. So those of you who can see it, which includes most of the world except for North America, once again, try to figure out a good way to see it. So we'll discuss it again next week on next week's show,

but it is on June 8th, Venus transit, very rare. It'll pass across the sun for several minutes. You'll need to have some safe way to observe the sun or cast an image of the sun to see it. It'll be a dark circle going across the sun. And by sheerest coincidence, we're, what, less than two months, I think, from the launch of the Messenger spacecraft, which is going to Mercury, but am I right that it's going

to pass Venus as well? Yes, indeed you do. Funny you'd mention Messenger. But we'll come back to that. Okay. All right, let's see what is up in the sky, since I was not able to say what's not there. But we'll be there in front of the sun. But in the evening, you can still see Saturn and Mars in the early evening in west-ish.

If you can find the twins in Gemini, Pollux and Castor, the bright stars, Mars and Saturn are below them. And Saturn is below Mars and brighter. And then Jupiter, brightest thing up there now that Venus is out of the way. And Jupiter is up there in the early evening. You can see it almost overhead, just past it, heading towards the west. So those are good planets to go see. We've also got a whole lot of other good space to look at. So do that. Let's move on. On to random space facts. Excuse me. Did you know, Matt,

that the giant planets vary tremendously in how giant they are and also how massive they are. As an example, the largest planet, of course, Jupiter, is about 317 Earth masses, whereas Uranus, compared to that, is a wee bitty 15 Earth masses. So 317 versus 15. You know, I've been looking at these guys for a long time, and I didn't realize there was that much of a disparity between them. But then again, we've also been hearing in this program just a few minutes ago about planets that put Jupiter to shame, kind of like when they made Alaska a state, how it made Texas feel. I'm glad you like that one.

Exactly. Yeehaw. Okay. Apparently I'm still running a little slow from being under the weather. Slowly. I can't even use my adverbs properly. I don't know how I'm running. I'm not running at all.

I'm walking. Nay, I am crawling. Let us move on to the trivia contest, shall we? Please. Last week we asked you, how many orbits did Apollo 8 make around the moon? How did we do? We got a good sheaf of entries since we went back to just a factoid, a trivia contest this week. And our winner, one of many who had the correct answer, is one of our regulars.

I don't believe she's won in quite a while. Hannah Beck of Ridgefield, Connecticut. Hannah Beck said that Apollo 8 circled the moon ten times before safely returning to Earth. Yay! She'll get one of our fabulous Planetary Radio t-shirts. So, congratulations. And moving on to this week's trivia contest. You happened to mention Matt.

Matt Messenger. Messenger Matt. That's my job. Good job. Well, I'm going to ask people this week to go answer our trivia contest of what MESSENGER stands for. It's one of the longest acronyms out there in the planetary exploration world. Good Lord. It amazed me that it's an acronym.

It didn't even occur to me that that could possibly be an acronym. It's so long. MESSENGER. Okay. Indeed. When shown in print, it is correctly all capitalized. So tell us what the acronym MESSENGER stands for. Go to planetary.org slash radio.

Enter our trivia contest. Try to win that wonderful Planetary Radio t-shirt. And do try to enter by this coming Thursday. What would that be? The 3rd of June, June 3, 2004, by noon Pacific time, if you would, because that will help us to make sure that your entry makes it into next week's What's Up contest. In my deluded state, Matt, I forgot to mention our friends the Comets. I do want people to see that.

Oh, please do. We have a couple of moments left. They're still up there. Comet NEAT, or as we now call it, the bucket full of marmots, Comet NEAT, or as we now call it, the bucket full of marmots, discussed in last week's show, is fading pretty fast. But you can still pick it up in binoculars if you've got a good sight. It will be off in the west-ish. How's Bob doing? I had to get that in. How's Bob?

Bob is doing great. Bob, also known as Comet Linear, is becoming visible again right around now for northern observers. It's been visible for a couple weeks for southern hemisphere observers. And it's visible also in the evening sky, also in the general direction of west. And is doing pretty well. And it is outshining NEAT now. So you can see it naked eye from at least a somewhat dark region. And you can definitely see it with a nice pair of binoculars, as I say, probably the best way to see a comet in the evening sky.

So go out and look for them. Linear also will be fairly brief in its apparition and starting to fade fairly soon. So go out and take a look. We've got finder charts linked from our webpage at planetary.org slash radio, and you can figure out exactly where to look for those old fuzzballs. Let me leave you with this, Bruce. One of my daughters got her entry in

for naming the comets, but she was too late, and I don't think she would have beaten a bucket full of marmots anyway. Pinky in the brain. That's their trademark issue. I bet Warner Brothers would have gone along with that, but anyway. the brain. Unless they're a trademark issue. It is, yeah. You can say not to do that. I bet Warner Brothers would have gone along with that, but anyway. Let's keep that in mind.

Okay. There'll be more. Are we all done? Oh, I hope so. I mean, yes. I think we are, Matt. Well, you keep recovering, and I hope to see you in person next time for the next edition of What's Up.

Sounds good. And everybody, look up in the night sky and think about bubble gum. Thank you. Good night. The inexplicable but recovering Bruce Betts is the Director of Projects for the Planetary Society. He joins us each week here for What's Up. That's it for this edition of Planetary Radio. We'll be back out there in the cosmos again next week.

I hope you'll join us. Take care.