What Makes Our Solar System Special?

Researchers say that if the conditions had been slightly different for our solar system, planets could have careened into the sun or been expelled into deep space. Also: A volunteer astronomer spots a strange gaseous object some are calling a "cosmic ghost."

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IRA FLATOW, host:

You're listening to Talk of the Nation: Science Friday. I am Ira Flatow. In a little bit later in the hour, we'll be talking about drug testing in the Olympics, but up next, continuing more space news. First, a new study makes the case for why our solar system is special, why is it unique. Astronomers have long figured that solar systems similar to ours could probably be found all over the universe. But a new model that simulates the birth and evolution of planets shows that conditions need to be just, just right to get a solar system like ours. We're going to hear about that.

And a strange new space object has just been discovered by a Dutch schoolteacher named Hanny van Arkel. She was participating in an online research project called Galaxy Zoo. She was cataloging images of galaxies when she saw something in one image that she couldn't place. She couldn't find it, you know, match it up in the galaxies. Well, it turns out that astronomers don't know for sure what it is either. They've dubbed it a cosmic ghost, and hope to get a better look at it next year when they can get some telescope time on the Hubble Space Telescope.

One of the cofounders of the Galaxy Zoo was here to talk about this comic ghost - cosmic ghost. And hello, armchair astronomers. If you are one of them can pitch in on the project, our number is 1-800-989-8255, 1-800-989-TALK. As always, you can join us also in Second Life. Search for Science Friday's Island. Let me introduce my guest. Edward Thommes is an adjunct professor in the department of physics at the University of Guelph in Guelph, Ontario, and he joins us today from his office. Welcome to the program, Dr. Thommes.

Dr. EDWARD THOMMES (Physics, University of Guelph): Thank you. It's a pleasure to be on the show.

FLATOW: Kevin Schawinski is a cofounder of the Galaxy Zoo Project and a post doctoral associate in the Yale Center for Astronomy & Astrophysics at Yale in New Haven. And he joins us today from the campus there. Welcome to the program, Dr. Schawinski.

Dr. KEVIN SCHAWINSKI (Cofounder, Galaxy Zoo Project; Post Doctoral Research Associate, Yale Center for Astronomy): Thank you. It's wonderful to be here.

FLATOW: Let me ask Dr. Thomas first, you have a new model that shows how our planets are formed, and what - does it tell us why we're so special?

Dr. THOMMES: Well, it seems to us, from these simulations that we did, that sort of a history of violence is the norm, rather than the exception, when it comes to the formation of planetary systems. And it seems like our own was a more rare and more orderly and peaceful instance of this process.

FLATOW: So, let's go through the two kinds. Let's go to the normal or the violent one first. What happens there?

Dr. THOMMES: Well, the violent one, which we think is the more common version, is - you basically have sort of a rapid succession of giant planets forming. We're talking here in particular about big things like Jupiter, like Saturn. So, we think these things are sort of popping out one after another. These discs out of which they're forming are basically forming planets early and often, and at the same time, the disc then pushes these planets inward and sort of pushes them up against each other. They gravitationally interact, and we get these sort of eccentric, elongated orbits and also these sort of closed-in, or what are often called hot Jupiters, which, interestingly, are exacting the sort of thing we see in many cases amongst the exoplanets that have been discovered.

FLATOW: But you say that's not what you think happened to our solar system.

Dr. THOMMES: Well, what we think happened in our solar system is that we are an example of a system that was sort of near the boundary between something that actually formed gas giants, formed, well, the Jupiter and Saturn that we see today, and something that if conditions had been a little bit different wouldn't have really formed any gas giants at all. It would have just contained a bunch of smaller rocky terrestrial bodies, maybe a couple of Neptune mass things. And because of that, the planets, the gas giants which did form, had a relatively peaceful birthing process and their orbits essentially stayed relatively close to where they were originally born.

FLATOW: And we had to have just the right conditions for that to happen?

Dr. THOMMES: It seems like you need a fairly narrow range of conditions. You kind of - you have to have the planets that do form forming just in time. They don't form too early. They don't form too late. So, the conditions have to be relatively tuned in order for that to happen.

FLATOW: 1-800-989-8255 is our number, talking about the planetary formation. So, that means that there was not that violence in our solar system.

Dr. THOMMES: Not really, I mean, it's all relative. We think there may have been some violent events in our solar system. It's possible that the smaller giant planets - Uranus and Neptune, these guys are usually called ice giants rather than gas giants - they may have had some violence in their history. And we had this event later on called the late heavy bombardment, which we think took place in the terrestrial regions. So, it's all relative. Even in our relatively sedate system, violent things probably did happen. But what we think is that the really big guys, Jupiter and Saturn, had it relatively easy and they didn't suffer so much at this.

FLATOW: And how are you able to come up with this idea? Is this something you thought up on your own? Or did you look at other planets out there and say, hey maybe we had a little bit different evolution than they did?

Dr. THOMMES: Well, there's been this sort of almost disconnect in a way between these exoplanets that we have been discovering in our own system because we have been really finding all of these hot Jupiters and eccentric planets. And certainly for awhile, and even now still, it does make sense to a degree that the hot Jupiters are simply easier to find and they're quicker to find.

So, to a large degree, we are still suffering from what scientists call selection effect. We don't really see the true distribution of these planets. But at the same time, what we started to understand about the formation process, we thought there would indeed be a lot of these orbits of giant planets spiraling inward after they're born and things that give you, for instance, hot Jupiters. And then we started, you know, scientists, astronomers started to wonder, well, why is it that Jupiter and Saturn seem to be pretty much where we expect them to have been born? And so that was sort of the jumping off point in what we did.

FLATOW: Let me turn now to Kevin Schawinski and this cosmic ghost. Why are we calling this a cosmic ghost?

Dr. SCHAWINSKI: The reason we call it a ghost is because we believe it is something called a light echo. It is sort of the dying embers of what we think was a very luminous and powerful event in an object right next to this ghost. And it may encode some information about the past of a super massive black hole.

FLATOW: So, that is what you're seeing - we're seeing information about the past, the history of the black hole?

Dr. SCHAWINSKI: Yeah, it's essentially an echo. It's what we call a light echo, an effect that we've seen around supernovas - stars that explode - and because of the vast scales involved, the speed of light is actually very slow. And so, you can actually, like, in an echo in sound, you can see the light moving outwards. And so, what we believe in this case happened is there used to be an extremely luminous quasar right next to this gas cloud. But this quasar has now disappeared. It shut down. But this gas cloud, because it is so far away, about 40,000 light years is still seeing the quasar, though we are not.

FLATOW: Wow. So, it's just shining there.

Dr. SCHAWINSKI: It's just shining.

FLATOW: So, is it moving towards us or away from us?

Dr. SCHAWINSKI: It's right next to this galaxy with the telephone number IC249,7 and it's sort of in our cosmic backyard. It's not incredibly distant, but it's also not exactly nearby.

FLATOW: I find it surprising. I'm always delighted to hear that amateur astronomers continue to make these interesting discoveries and - in something called the Galaxy Zoo Project. Tell us what that is.

Dr. SCHAWINSKI: The Galaxy Zoo is an Internet portal that invites members of the public to participate in astrophysics research. The basic task that we have as astronomers studying galaxies is trying to classify them and divide them into their basic categories, which have been with us almost a century. There are spiral galaxies, like our own Milky Way, and then there are elliptical galaxies, sort of football or rugby ball shaped. And it turns out, that computers are actually not very good at distinguishing the two classes. And nowadays, we have so much data with these vast surveys with millions of galaxies and it's just impossible for small teams of astronomers to sort through them by hand, by eye, and classify them. And so we invited members of the public to do this with us.

FLATOW: Are members still open to join?

Dr. SCHAWINSKI: Absolutely, anybody can do this. Anybody can sign up at galaxyzoo.org, and after a brief tutorial where you just see some examples of what you're supposed to look for, you're ready to go. And the really marvelous thing is that after about 10 minutes of training, most people are as good as professional astronomers at this.

FLATOW: Wow. Is there a name, besides cosmic ghost - has this been named, this object?

Dr. SCHAWINSKI: Yeah, as discoveries usually are named after their discoverer, it has been named after Hanny van Arkel, but instead of calling it Hanny's Object, it quickly became known in our online community as Hanny's Voorwerp - voorwerp simply being the Dutch word for object but it sounds cooler.

FLATOW: And a lot easier for you to say than for me to say. 1-800-989-8255, while we get some phone calls up there. And you can have some telescope time on the Hubble to get to take a better look at this?

Dr. SCHAWINSKI: Yeah. So, next year after the service mission with the space shuttle, which will hopefully take place later this year, after the new instruments that are going up have been installed, and the old instruments that have broken have been repaired...

FLATOW: Mm-hm.

Dr. SCHAWINSKI: We'll hopefully get a really fantastic look at it.

FLATOW: Mm-hm. Cora in San Antonio, welcome to Science Friday. Hi.

CORA (Caller): Well, hi. Well, I'm always calling, I'm never on and today it's, like, oh, I'm on, so excited. Anyway, I had a real good conversation just last weekend with a young friend who is Bible-oriented and I'm evolution-oriented. And yet when I was confronted with a question, but how did it all began, did we come out of nothing? What kind of an answer can I give him? You know, how can say, well, it always was. Well, that's what God is...

FLATOW: Mm-hm.

CORA: You know, he always was in and he created it.

FLATOW: Mm-hm.

CORA: How do I answer that?

FLATOW: Edward...

CORA: I'll take my answer off the air.

FLATOW: OK.

CORA: Thank you.

FLATOW: You're welcome. Edward Thommes - or Kevin, you want - can anybody give a shot at that?

Dr. THOMMES: A little bit outside of my area, I think, where we can sort of just deal with the stuff that the life stands on after it's created.

FLATOW: Mm-hm. Kevin, any...

Dr. SCHAWINSKI: Similar answer, I mean, I think the best starting point is to look at the universe around us, and see what does nature tell us, what can we learn about the universe...

FLATOW: Mm-hm.

Dr. SCHAWINSKI: And over the last centuries and in particular the last century, we've learned an awful lot about what our place in the universe is. And that knowledge is still, you know, not complete, but it does tell us an awful lot.

FLATOW: Mm-hm. 1-800-989-8255, a caller to - let's go to Lynette in La Fargeville, New York.

Hi, Lynette, are you there?

LYNETTE (Caller): Hi. Yes, I'm here.

FLATOW: Where is La Fargeville? Where is that?

LYNETTE: La Fargeville, we are a little over an hour north of Syracuse, New York.

FLATOW: Ah.

LYNETTE: We're the Canadian border.

FLATOW: Right by the Finger Lakes, and right by the Great Lakes.

LYNETTE: North of the Finger Lakes.

FLATOW: Closer - Great Lake area.

Dr. THOMMES: Yeah, OK.

LYNETTE: Yes, we're near Lake Ontario, actually.

FLATOW: Mm-hm, all right. Go ahead. Do you have a question?

LYNETTE: Yes, I do. I have a friend who's very interested in things astronomical, and he told me that our sun is our second sun. Is that true?

FLATOW: You mean S-U-N?

LYNETTE: Our sun, S-U-N. Right. Our sun, our star.

FLATOW: You want to get into family matters here, then.

(Soundbite of laughter)

LYNETTE: Is that - I - and I didn't question him, because he's quite, you know...

FLATOW: Yeah.

LYNETTE: You know, he's somewhat of an authority or (unintelligible)...

FLATOW: Precocious. OK. Let's see if we get an answer for you.

LYNETTE: OK.

FLATOW: Gentlemen?

Dr. THOMMES: That's an intriguing statement.

FLATOW: Any reaction? How do we know this is our first sun?

Dr. SCHAWINSKI: Ah...

Dr. THOMMES: Well, as far as we know, it - this - our sun goes back to about four and half billion years, and I don't know of any indication that we ever swapped suns with anybody, but it's...

LYNETTE: Or that there was a second - second - oh, dear...

FLATOW: You mean, like, we have two suns?

LYNETTE: I know I'm really going to go out there. I'm going to say a second coming. What I mean is, like, a second explosion or whatever formed the first one.

Dr. THOMMES: Because with something that has been sort of bandied about is the theory that we've had a close encounter with another sun, with another star in our past, and there are actually some traces in the outer ranges, in the outer reaches of our planetary system, in the so-called Kyper Belt, that there may have been some gravitational disturbance in the past, which may have flung things around, and one of the theories is that we may just have had a sort of, you know, two-ships-passing-in-the-night kind of thing with another star.

FLATOW: Mm. Interesting.

LYNETTE: OK.

FLATOW: All right?

LYNETTE: OK.

FLATOW: Maybe Kevin wants to drop a comment there.

Dr. SCHAWINSKI: Sure. I think there's another possibility for that I might refer to. It might be the fact that he meant that our Sun is a second generation star. Our sun is enriched with heavy elements, with metals, and oxygen, and so forth, that have to have been made inside another star that died before our sun and our solar system formed.

FLATOW: Ah.

Dr. SCHAWINSKI: And so our sun is at least a second generation, if not the third generation star.

Dr. THOMMES: Ah, yes. That might be what he meant indeed.

FLATOW: We're talking about the solar system this hour of Talk of the Nation: Science Friday from NPR News. Explain that a bit more. The sequence would be what, Kevin?

Dr. SCHAWINSKI: So, in the very early universe, most of the elements that were made in the Big Bang were hydrogen and helium, and very few trace elements of heavier elements, like oxygen and iron and so forth. And these heavy elements are very important for making stars, because they allow the hydrogen and the helium to clump together, and collapse into stars then, and start to shine. And so the first generation of stars was probably very massive and short-lived...

FLATOW: Mm-hm.

Dr. SCHAWINSKI: Though this very much - a lot of work going on in that topic at the moment - that then seeded the material around it, as these stars exploded in supernovae, allowing the second generation of stars with a little bit more heavy elements to form, and then probably, you know, our solar system and our sun was made - was probably - has gone through the cycle probably at least a couple of times, before this particular cloud collapse that gave us our sun and our solar system around it.

FLATOW: Where do we still see remnants of those originals, any around?

Dr. SCHAWINSKI: They probably would have disappeared a long time ago.

FLATOW: Yeah.

Dr. THOMMES: And this fact that we are a later generation is probably also good news for our existence here, because what observers have been finding is that it is the more metal-rich stars that are seem to be more likely to have planets orbiting them. So, there seems to be - it seems to be the case that a higher content of heavy elements actually helps you form planets

FLATOW: I - in the few moments we have left, Dr. Thommes, what would be the chance of finding a solar system just like ours, if it's so special?

Dr. THOMMES: Well, it's more rare. Having said that, it's certainly not unique. I mean, even in our, you know, hundred or so simulations, we found several that sort of resembled the solar system. So, we think there are more of them out there.

FLATOW: Mm-hm.

Dr. THOMMES: We had have ordered a few percent of systems that where the giant planets at least resemble the architecture in our own system, as to whether we would then have terrestrial planets in the habitable zone, the chances of that actually aren't too bad, because the terrestrial planets, we think, they kind of sprout like mushrooms pretty much anywhere.

FLATOW: Right.

Dr. THOMMES: So, that's - that is the picture that we have. Well, gentlemen, I want to thank you for taking time to be with us. Good luck in your work.

Dr. THOMMES: Thank you very much.

Dr. SCHAWINSKI: Thank you.

FLATOW: You're welcome. Kevin Schawinski is cofounder of the Galaxy Zoo Project and a post doctoral associate at the Yale Center for Astronomy & Astrophysics at Yale University in New Haven, Connecticut. Ed Thommes is adjunct professor in the department of physics at the University of Guelph in Guelph, Ontario, Canada. Have a good weekend, gentlemen.

We're going to take a short break and when we come back, we're going to talk about the Olympics. This is the first day of the Olympics. Ceremonies are getting underway. And also, there's already talk about doping there. We'll talk with a scientist about that issue. Stay with us. We'll be right back. I'm Ira Flatow. This is Talk of the Nation: Science Friday from NPR News.

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