Planetary Radio: Space Exploration, Astronomy and Science - First Earth-Sized Exoplanet is Next Door!

Episode Date: December 10, 2012

Xavier Dumusque is the young astronomer who was lead author for the announcement of the first exoplanet found in the Alpha Centauri system, just 4.3 light years from Earth. It's also the first Earth-sized world found outside our own system.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

An Earth-sized planet, right next door, this week on Planetary Radio. Welcome to the travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. It has been nearly two months since we learned that the first Earth-sized exoplanet had been discovered orbiting Alpha Centauri b. We'll talk with Xavier Dumasque, the lead author of the paper that revealed this find. Later in the show, we'll reveal what you, our listeners, thought Curiosity should have found on Mars. But we'll begin by visiting once again with Senior Editor Emily Lakdawalla.

Emily, it was great to see you and work with you at that big galaxy event that our friends at Cartel put on last Friday. We'll come back to that in a moment, but first, I guess it was in preparation for that that you found some really historic images. Yeah, I was asking myself what some of the first pictures were from space, and I found these Mariner 4 photos. And, of course, Mariner 4 took under 20 pictures, a very small number of pictures of Mars. And there were a first view of a Mars that was covered in craters. And there's a wonderful comparison showing, you know, much, much better images that we can make now. My, we've come a long ways, compared to what was sent back by Mariner 4. And the difference is so striking.

Actually, it's funny that you mention that comparison because the comparison isn't even to a very modern camera. It's to the Viking images. Because if you look at a modern camera's images of Mars, they're so tight, they're so tightly focused on small areas that you really can't see the wide expanses that the Mariners and Vikings saw. Yeah, that's why there's a context camera, right? That's right.

Let's turn to this Galaxy event. It was last Friday, December 8th, at something called L.A. Mart, which has an empty floor, and these folks from Cartel put on this big event, Science Art Party. You helped provide the science. Yeah, I did, and what a fun crowd that was. I have to say, much more expressive and responsive than my usual audience. They were great. And I showed them lots of really beautiful photos from Mariner 4, from much more recent Mars exploration, like Curiosity's work, and from

Cassini at Saturn. And they were mesmerized and appreciative, and I had fun talking to them. Let me play just a few seconds of what you had to say. A little bit of your conversation. You were showing them, actually, all the unexplored worlds in our solar system. Now, there are actually now eight planets in the solar system. How many of you are unhappy about Pluto's demotion? Let me show you something kind of interesting about our solar system. The rest of the solar system, there are 20 other round worlds inside this 8 planet solar system. We have of course our own moon and Ceres and asteroid and the moons of Jupiter, Saturn, Uranus and Neptune.

They are, all of the round ones are Io, Europa, Ganymede, Callisto, Minus, Enceladus, Tethys, Dione, Rhea, Titan, Iapetus, Miranda, Ariel, Umbriel, Titania, Oberon, and Triton. Those are all of the other grand things in the solar system. Even more exciting than all of those round worlds in the solar system, I want you to look way down at the right-hand corner of this montage. There are, if you can see it, there are 200 round worlds beyond Neptune. It's not just Pluto and Pluto's moon, Charon. It's Eris. It's Haumea.

It's Make Make and Quabar and Sedna and Veruna and countless other really exciting worlds that we haven't even begun to visit yet. So it's up to you guys to imagine what they look like. So that's Emily at Galaxy just last Friday, this big science art party that was put on here in L.A. Great fun. Just one more thing to mention, Emily, I guess we've got another big one flying by. Yeah, we have an alien visitor. It's asteroid 41792 TARDIS is going to be making a close approach. It does that every four years. And as usual, radar will be shooting it to make beautiful photos. But this time it's getting a

visitor from Earth, which is the Chinese Chang'e 2 spacecraft, used to be a lunar orbiter, now on its way to an asteroid. Very cool. And that closest pass will be Wednesday, the 12th of December, so if you are hearing this program before that, you might be able to get in on it online. We'll try to find some links for you.

Thanks so much, Emily, and I look forward to having you on stage with us at Planetary Radio Live next week. Can't wait. She's Emily Lakdawalla, the senior editor for the Planetary Society and our planetary evangelist, also contributing editor to Sky and Telescope magazine. I will be right back when we'll take you to an Earth-sized planet near Alpha Centauri. It was a discovery that electrified the astronomy community and the public. In mid-October, the European Southern Observatory announced it had found the smallest exoplanet yet,

and it found it barely four light-years from our home system. This was largely thanks to HARPS, the High Accuracy Radial Velocity Planet Searcher, but much of the credit also goes to the young lead author of the paper published in Nature. That author was Xavier Dumas. In a recent Skype conversation, Xavier described this new world to me along with the painstaking work that made its discovery possible. Xavier, thanks so much for joining us on Planetary Radio and congratulations to you and your team on this stunning discovery that has attracted so much attention around the world. Yeah, it's a pleasure

to talk to you also. Yeah, it's true that it has been a big discovery. I didn't expect it that there have been so much media interest in this. But it's true that in the American side, there really have been a lot of interest. You bet. And this was very, very nice. Yeah, we've been hearing it from our listeners for the past couple of months, wondering when we're going to have you or someone else from the team to talk with us. But as lead author, I'm especially happy to have you on.

Let's start with having you tell us a little bit about this world that you and your team have found. So this world, the thing is that we are continuously finding some new exoplanets, but this one is really special in the sense that it's the smallest that we have discovered so far. So if you think about its mass, it's a mass that is similar to the one of the Earth. So this is really the lightest one we have discovered yet. And the signal is so small that it was really difficult to find it. You cannot just look to the data and you see the signal in this. So you have, first of all, to analyze,

to remove plenty of different type of signal before discovering this planet. And so it has been a big challenge. And so this planet is Earth's mass orbiting the star, so Alpha Centauri b, which is one of the closest stars to us. So it's four light years from us. It's really close, if you think in terms of the galaxy. And so this planet is orbiting the star in three days. So it means that the planet is very close to the star. And for example,

if you compare this to the solar system, the closest one is Mercury, which is at 100 days of period around the sun. And so this planet is seven times closer than Mercury to the sun. So it's very close. And since it's very close, it's also very hot. So we estimate more or less the surface of this planet to be at 1,000 Kelvin, more or less. So the temperature is very high. So for the moment, we cannot expect any type of life. No, and that, of course, is the famous now almost cliché quote, no life as we know it is likely on this planet. What evidence do you have for this being Earth-like in the sense that you suspect it is a rocky planet?

When you arrive to this type of mass, one Earth mass, the material that you have is not massive enough to acquit some gas on it. So you start to acquit some gas when the planet is something like 10 Earth mass. You start to acquit some gas when the planet is something like 10 Earth masses. So basically, what you have below 10 Earth masses, it's a rocky cause. So we are quite sure that this planet is a rocky planet. This is quite evident. Is there reason to believe in this system that is so close to us that there may be additional planets farther out from one of these stars and therefore more difficult

to detect. Yeah, this is exact. If you look to the big detection technique, the detection technique that have found the most planets nowadays, you have two techniques, basically transit and radial velocity, the one we have found, Alpha San B. And basically, these two detection techniques arrive to the same conclusion that when you go to small mass planet, you don't have just one planet per star, but you have a lot.

If you have small mass planet, you have multi-planetary system. So it's true that in this system Alpha Sun B, we have found this planet as three days. There is a lot of chance to have also other planets further away. And why not a planet in the habitable zone? The thing is that the technique that we use, so the radio velocity technique, which

basically, you look not to the planet because you cannot see it because it's too faint. So you look to the star and if you see the star moving a little bit, you know that there is something orbiting around and with this technique the further you go from this from the star the smallest will be the amplitude of the effect so here's three uh here's three days of period with a nose mass planet

it's a 50 centimeter per second of speed of the planet of the star so it so this is really tiny this is at four light years so it's a thousand of billions of kilometers away from us so you can detect a 50 centimeter per second it's three kilometers per hour it's really really tiny and so if you imagine for example a an Earth-mass planet at 200 days, which would be the zone where there could be liquid water on the surface of this planet. So the effect would be not 50 centimeters per second, but 10 centimeters per second. So even five times lower. And this was already very challenging to find 50 centimeters per second.

So for the moment, we don't have the detection capabilities to find Earth-like planet as we know it, as the Earth, with water liquid on it. I love, to put this in context, the comparison that is given in the press release that came out

in October, which is that this 50 centimeters per second is roughly the speed that came out in October, which is that this 50 centimeters per second is roughly the speed that a baby crawls, which is, and you know, 4.3 light years, yes, close, but still a long ways. My conversation with Xavier Dumas continues in a minute. This is Planetary Radio. Hey, Bill Nye here, CEO of the Planetary Society, speaking to you from PlanetFest 2012, the celebration of the Mars Science Laboratory rover Curiosity landing on the surface of Mars. This is taking us our next steps in following the water and the search for life, to understand those two deep questions.

Where did we come from, and are we alone? This is the most exciting thing that people do, and together we can advocate for planetary science and dare I say it, change the worlds. Hi, this is Emily Lakdawalla of the Planetary Society. We've spent the last year creating an informative, exciting, and beautiful new website. Your place in space is now open for business.

You'll find a whole new look with lots of images, great stories, my popular blog, and new blogs from my colleagues and expert guests. And as the world becomes more social, we are too, giving you the opportunity to join in through Facebook, Google+, Twitter, and much more. It's all at planetary.org. I hope you'll check it out. Welcome back to Planetary Radio.

I'm Matt Kaplan. A hot little world is revolving around a star like our own that is just 4.3 light-years away. Our guest this week, Xavier Dumas, is lead author of the paper that announced its discovery in nature a few weeks ago. We have talked in the past, at least once on this show, about this exquisite sensitivity of the harps instrument. But you've already mentioned that it wasn't just harps. It's the fact that you had to subtract out all the natural noise of this star and, in fact, the nearby star. And I would suggest that people take a look at the actual paper, which is available at the ESO.org website.

We'll put up a link to this, by the way. That's the European Southern Observatory, of course, which made this announcement. And it goes into some detail as to how you and the team did this work. Can you tell us a little bit about what you had to compensate for? At this level of precision, we have 50 centimeters per second, 1 meter per second. The thing is that the stars are not static, they move. So what, for example, the surface of the star, it's very warm. I would say the surface is like boiling water if you want.

It's not water in this case, it's plasma. So it's melted rock if you want. But basically you have some bubbles of plasma that goes up and some other that goes down, like in boiling water. And at the precision we are, we start to see all these effects that are appearing on the surface of the planet. So this induces an effect of about one meter per second, something like that. So really of the same level as the planetary signal. And then you have other effects. For example, when you look to the sun.

So for example, when the sun is not active, because the sun has an 11-year activity cycle, and when the sun is not active, for example, you don't have any spots on the surface. You can see some dark spots sometimes on the sun. And when the Sun is not active, you don't see anything. When it's active, you see a lot of spots on the Sun. And you have exactly the same for Alpha Centauri b, because it's a star that is very similar to our Sun.

If you don't have any spot, you will not have any signal from this activity. And when you will have a lot of spot, this will create some signal. So this is another type of signal that will also cause us some problems when we want to detect very small signal due to planets. Xavier, I want to switch gears here for a moment. And I hope you don't mind my asking, how old are you? So I'm 27 now, so soon 28 in one month. All right, well, happy birthday in advance. But very young for not only to be a co-author of a paper like this, but not co-author, the lead author in this discovery.

How is it that you came to be able to do this? So I think this is just because we have a very nice team here that give a lot of power, if I want to say, to students. One year ago, they gave me this wonderful data that we have on Alpha Centauri B. So now I'm finishing my thesis. All the work during my thesis was on analyzing all these kind of stellar signals and everything. So I was the guy to do this analysis in the team here in Geneva. And then they were very kind to give me this paper, I would say, because it's true that it's really a big thing. Your mentor and colleague, Stéphane Oudry, said very nice things about you.

I think it's looking good for you for your PhD. When do you hope to achieve that PhD? So I defend my thesis, in fact, in one week. So next Monday. Well, then I'm especially grateful to you for taking time with us today because you have a lot of other things on your mind. Best of luck with that.

Let me finish with this question. I mean, you've already indicated that we need about a five-fold improvement to find Earth-like planets or sized planets out at the orbit that we would call the habitable zone. Do you see this coming? Is it just a natural progression as we get better and better at this? Here in Geneva, and with a big collaboration in Europe, we are building now a new instrument, which is called Expresso. It will be normally finished in 2016. And so now ARPS, the best instrument in the world to search for planets with the wide-diversity technique,

Now ARPS, the best instrument in the world to search for planets with the wide-areocity technique, is at one meter per second of precision, basically. And so this new instrument will be at 10 centimeters per second. Wow. And as I said before, 10 centimeters per second is the effect of the Earth on the sun. So basically, this new instrument will have the precision to find other Earths, I would say, other Earth twins. The only problem is that, as we said already, at the meter per second precision level, we have all these kind of signals coming from stars and not from the planet orbiting around. So we don't know yet if it will be able to correct all this type of signal to go down to 10 cm per

second. This will be the next challenge. And I would say that this paper on Alpha Centauri b is really interesting from the point of view that it's a very small mass planet, that it's orbiting Alpha Centauri b, the closest neighbor to the Earth, but also because it's more or less the first time that we have characterized all the type of stellar signal, at least the one that we know, and we have started to remove their effect from the data. And it's more or less the first time that we do this, I would say, in a general way,

with all the type of signal just for one star. I would say in a general way with all the type of signal just for one star. And so this is an important step for Expresso that will be able to find us if we manage to correct all this type of signal. Well, Xavier, we are out of time. I thank you for the discovery of this world and for giving us hope that much, much better things are in store. And I look forward to talking to you again. At that point, we will call you, I'm sure, Dr. Dumas. Best of luck with that.

Thanks a lot. He is Xavier Dumas. He was the lead author of this paper that was trumpeted in mid-October because it discovered the smallest ever exoplanet circling a star only 4.3 light years away, the famous Alpha Centauri, actually Alpha Centauri B in this case, in that triple star system. Xavier is, as you heard, going after that doctorate. He is at the Geneva Observatory in Switzerland, also the Center for Astrophysics at the University of Porto in Portugal.

We're going to talk with another astronomer. Yep, it's time to speak with Bruce Betts. And we'll find out what else is up in the sky in just a few moments. Time for What's Up on Planetary Radio. Here's Bruce Betts, the director of projects for The Planetary. He says, I'm a little hoarse. I was out late last night because I went to see Wait, Wait, Don't Tell Me, the NPR show. You're familiar with it? Oh, yes.

And I now know the only difference between that show and Planetary Radio Live is that they don't have science. Really? Yeah. So we have a big advantage. Okay. Okay, well, you know what they also don't have is a rundown of the night sky. Huh? Or clever segments like that.

They probably will start next week having heard you say that. I'm sure. They probably will start next week, having heard you say that. I'm sure. So check out Jupiter bright in the east in the early evening, all through the night getting overhead. And in the pre-dawn, extremely bright Venus, still dominating with Saturn up above it, much dimmer and yellowish. And don't forget the Geminids meteor shower, the best meteor shower of the year on average, with an average of 60 meteors per hour. That's one per minute on average, Matt.

Let me see. Wait a minute. Yeah, that's right. One per minute. From a dark side. And that peaks on the 13th and 14th, and it's particularly groovy this year because it's new moon time, so there's none of that pesky moonlight to interfere. Hope it's clear here.

It is a bit of a broad peak, so if you get clouded out right on the peak, you can check it out a couple days before or after. This week in space history, it was a big, big week. 50 years ago this week, first ever successful planetary flyby, NASA's Mariner 2 at Venus. 40 years ago this week, the last humans left the moon. Not quite as worth celebrating, but still very significant. But they went there. They did good stuff.

We can celebrate that. That's right. We move on to random space fact! It's amazing. How many? 500 of these roughly so far, and you're still finding new ways to do it. Every one of them. Kind of. Absolutely unique. Like fingerprints.

They're subtly different. So tidal effects cause the Earth's rotation to slow down over time. The interactions between the Earth and primarily the moon, and the moon to revolve slower and get farther and farther out from us. So even though this is a tiny effect on human time scales, over billions of years, the day has gotten longer by many, many hours. I've calculated that in another two billion years, I expect I'll be able to get everything done that I expect to get done each day.

All right. Something to look forward to. We move on to the trivia contest. We had our big humor fest trivia contest uh john grozikern the mars science laboratory principal investigator had uh had said in an interview with npr they had a discovery they would announce that would be one for the history books everyone went crazy crazy coming up with crazy theories and of course it really was just they have their instruments work really well and got really good base data. But we wanted you to tell us what the

discovery could have been or will be based on humor, creativity and originality. What was discovered by Curiosity on Mars? How'd we do Matt? You know, this is I know how we did. You do know because you've got half of them in front of you. I do. And we did better with this, or you guys, you listener types, did better with this than just about any of our previous silly make us laugh contests. We got some terrific responses. And

of course, we do not have time to read all of them to you here as part of the radio show. But we're going to post more than we have time to read on the radio show site, planetary.org slash radio. You can get to the episode page right from there. I think you'll enjoy it. There's some very good stuff here we just don't have time for. So we thank everybody. But let's get through. We're going to try to read a bunch. Yeah, we have a bunch. And

you're going to start us through the runners up. Okay, so what did Curiosity find on Mars? From Carol Novak of Poland, Mars Nazis, obviously. And probably related to that, here's what Daryl Gardner of Lake Stevens, Washington said we will find, or it has found. An Illudium Q36 explosive space modulator. Oh, I am so happy someone submitted a Marvin the Martian thing so you could do your very own question. You're happy.

That's been giddy about this ever since he got the entry. All right, moving on. A copy of the Earthling Chronicles. That from Derek Urbanowski of Seattle, Washington. Stephen Porter of Piedmont, California. One of two entries, actually. One that said, we brought this item with us on Curiosity to tempt the Martians. But Stephen actually says,

we found them there. What else? Twinkies. Nice. Here we've got a long entry I will attempt to summarize from Kurt Lewis of Missouri City, Texas. Basically, 65 million years ago, the impact that wiped out the dinosaurs shot part of Earth to Mars. They discovered it on Mars, including an infestation of cockroaches. Now we're sending a roach motel. A big one. A big one. Bug-sized. Volkswagen bug-sized. So here's sixth place.

From Ed Lupin in San Diego, I believe. The Curiosity rover has discovered evidence of ancient tanning salons, proving conclusively that there has never been intelligent life on Mars. And from John Kimberly in the United Kingdom, a copy of Douglas Adams' Hitchhiker's Guide to the Galaxy plus fossilized remnants of a towel. Yeah, I like that one a lot. Here's fourth place from Jeff Belback of Bethel Park, Pennsylvania. This is one of your favorites, I think.

It was a bag of marbles, believed to be that belonging to Tootles, one of Peter Pan's lost boys. Who lost his marvels. I've lost me marvels. Something like that. All right, moving on. From Stephen Hawkins. Oh, and this is third place, by the way, and I think we're going to send a T-shirt to these folks,

third place, second place, because they need something a little bit. They need to be rewarded. All right, from Stephen Hawkins. What'd they find on Mars? D.B. Cooper and to be rewarded. All right. From Stephen Hawkins, What'd They Find on Mars? D.B. Cooper and Amelia Earhart opening a Starbucks. Can you see it? As baristas?

That's a really odd vision. In second place, Torsten Zimmer, who sent us, he would be in first place for quantity, but he's got one that got him this highfalutin position in our ratings. Curiosity discovered a zombie, because they're everywhere these days. And now NASA scientists are debating whether they found life or not. There's the real challenge. And here is

our grand prize winner, who will get not just a Planetary Radio t-shirt, but one of those terrific year in space wall calendars that other people can get if they really want one. All right. What did Curiosity find on Mars? Waldo. Get it? Where's Waldo? It's a book series. You look for Waldo. Yeah. Waldo's got to be published all over the world. So we hope that those of you outside of North America get that. And we bet that you do. So there's Waldo. There's Waldo. Finally.

Stop looking for him in those pictures. Congratulations to all of you who entered. And, again, we'll have a bunch of them on the webpage by the time you hear this radio show. All right. We move on to a more mundane, well, that's probably a poor choice of words, but a simpler, non-humorous contest, unless you want to make it humorous. What is the most common graphical symbol for Neptune designed to look like? Hmm.

Okay. So a symbol, there are symbols for the planets. What's the one for Neptune designed to look like? Go to planetary.org slash radio, find out how to enter. You have until Monday, December 17, at 2 p.m. Pacific time to get us this answer. All right, everybody go out there, look up at the night sky, and think about Waldo on Mars. Thank you and good night. I used to love doing that with my daughters.

He's Bruce Batts, the director of Projects for the Planetary Society, and he joins us every week here for What's Up. Join us for Planetary Radio Live next week, featuring the leaders of the Curiosity Mars rover mission. You can watch the live webcast at 2 p.m. Pacific time on Saturday, December 15. The link is on our show page at planetary.org slash radio. Planetary Radio is produced by the Planetary Society in Pasadena, California, and made possible by a grant from the Kenneth T. and Eileen L. Norris Foundation

and by the generous members of the Planetary Society. Clear skies. Thank you.