A Travel Guide to the Solar System

From ancient mythology to the recent battle over Pluto's planetary status, people's imaginations have been captured by our companions around the Sun. Author Dava Sobel discusses her personal fascination with the eight (or nine?) planets, and how she expressed that interest in a recent travel guide to the solar system.

Copyright © 2006 NPR. For personal, noncommercial use only. See Terms of Use. For other uses, prior permission required.

IRA FLATOW, host:

This is TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow.

You know, there's probably not a kid out there who hasn't had to memorize the planets in our solar system or who hasn't fashioned a grammar school solar system in a shoebox. Remember, with a twisted bunch of wire hangers, maybe hang it as a mobile in your classroom. Remember that?

Or how about your first trip to the planetarium, leaning way back in that darkened auditorium to watch the stars come out and see the whole night sky, more than you could ever view from your rooftop or your backyard because it never got dark enough to see everything or the trees or stuff were in the way. Remember that? I remember that from the Hayden Planetarium of my early days here in New York.

And my first guest today has the same experiences, and when she did, she was hooked. She entered into a lifelong love affair with our solar system, the fruits of which come to bear in her most recent book, The Planets. So we're going to start the hour today with a guided tour of the solar system your planetarium may have left out.

You may not hear some of the stuff we're going to talk about today, from, let's say, the history of Mars as told by a famous Martian rock, to the story of Jupiter presented through the lens of astrology, and of course the saga of Pluto. Yes, recently bumped from the planetary lineup by the vote of astronomers - who was there. She was there when that happened, and we're going to get her account.

And of course I'm speaking of Dava Sobel. She's a science writer in East Hampton, New York, originally from the Bronx, right?

Ms. DAVA SOBEL (Author, The Planets): That's right. (unintelligible)

FLATOW: We New Yorkers, we can make fun of the Bronx.

Ms. SOBEL: Right.

FLATOW: She is the author of Longitude and The Planets, out there in hard cover last year and now out in paperback, and she joins me today from our NPR studios. Welcome back, Dava. Glad to see you.

Ms. SOBEL: Thank you.

FLATOW: Let's talk about the planets. What made you write the book The Planets? Was it that - were you influenced going to the Hayden Planetarium, as I was, when you were a kid?

Ms. SOBEL: Oh, absolutely. That's when it started for me and also in school because we had really good science instruction -

FLATOW: Yes.

Ms. SOBEL: - in grade school when I was a child, and I got very interested. And my mother was also an astronomy enthusiast and actually knew all the constellations. So I had all that nice preparation.

FLATOW: Remember that first experience going - when you went into the planetarium and you leaned back?

Ms. SOBEL: Oh, definitely, and we went every year in school, so it's an indelible memory now. I'm not sure I remember which was the first time.

FLATOW: Yeah.

Ms. SOBEL: But it was always exciting.

FLATOW: Yeah. You begin a book about the planets with the sun by quoting from the creation story in Genesis and then telling the scientific story of creation, the Big Bang. Do you think in this age of where we're trying to reconcile religion and science that the two can be reconciled this way?

Ms. SOBEL: Well, the planets certainly owe everything to the sun.

FLATOW: Right.

Ms. SOBEL: They were all formed at the same time, and that is the creation story that most of us have been told. Scientifically, I don't think they can really be reconciled. But in this book, all links to popular culture were fair game, and I wanted to talk about the planets in ways that would be familiar to people who were not necessarily informed or even interested in astronomy.

Much to my surprise, I actually won an award from a religious magazine for that chapter, which was a dubious distinction for me actually. I took a lot of risks like that in this book.

FLATOW: Yes. Why?

Ms. SOBEL: Again, to underscore the fact that the planets have played a role in popular culture from before the written word. They were the most obvious thing in the night sky after the moon or even after the sun. In fact the sun and the moon were considered planets by some of the earliest people because they moved. Planet just means wanderer, so anything that was moving with regard to the fixed stars was a planet.

FLATOW: And so much of early science revolved, so to speak, around those planets. Right.

Ms. SOBEL: Around figuring out what that was about, why they moved the way they did, why they looked the way they did. It was a great puzzle.

FLATOW: Yeah, 1-800-989-8255.

Now, let's talk about Pluto for a little bit.

Ms. SOBEL: Yes.

FLATOW: Because I know you're an expert on it and you have some inside information about the casting off of Pluto from the realm of planethood.

Ms. SOBEL: Well.

FLATOW: What's your view on that?

Ms. SOBEL: Well, frankly, the whole issue about Pluto was about coming up with a definition for this word planet. Because it's never had a scientific definition. And so contrary to what you've heard or said yourself, the whole meeting in Prague was not really about whether Pluto should be kicked out of the solar system, but really how to define the word and how to decide whether the Hayden Planetarium did the right thing when it dropped Pluto from the list of major planets a few years ago or whether some of the new bodies that have been discovered can be considered planets.

So I was on the committee that drafted the resolution. And then that draft was presented to the world community of astronomers for voting. And as you know we were shredded in the voting. But it was a very interesting experience because our group of seven people represented widely differing opinions, but after two days of talking, we had reached unanimous consensus -

FLATOW: It was - go ahead. I'm sorry.

Ms. SOBEL: - and we would have - our definition would have left Pluto in. Also would have included a few other small bodies, so we would have had a solar system of 12 objects.

FLATOW: But that was rejected.

Ms. SOBEL: Yes. And I really think that both takes are fair. Any definition is arbitrary. You have to come down hard on some things, somewhere, and some people are going to be upset. I've been stunned by how upset people are.

FLATOW: Yeah.

Ms. SOBEL: They feel that Pluto's actually been physically ejected from the solar system.

FLATOW: It's surprising the amount of emotion.

Ms. SOBEL: Amazing.

FLATOW: Yeah.

Ms. SOBEL: And now I ask people why are you upset? And for many people it's just a question of change. They feel so much has changed, so much has been taken away from them, why does this treasured memory of childhood have to be affected?

Others feel it was some kind of cruel plot or just whimsical behavior on the part of planetary scientists, but it really is this difficult attempt to frame a good definition.

FLATOW: And it doesn't affect the scientists very much, does it?

Ms. SOBEL: Well, at the moment it does because they're not in agreement.

FLATOW: Yeah.

Ms. SOBEL: Some of them feel that the new definition is still unsatisfactory, and I think -

FLATOW: And that definition is, the new definition?

Ms. SOBEL: Well, basically it's a body in orbit around a star that is big enough for its own gravity to have shaped it round, and it has to be the dominant body in its orbit.

FLATOW: It has to carve out an orbit for itself?

Ms. SOBEL: Right, without other things -

FLATOW: Right.

Ms. SOBEL: - having as much importance in that orbit.

FLATOW: Right.

Ms. SOBEL: Pluto, for example, has its big moon Charon and many other things in its orbit so that it's not dominant the way Neptune or Saturn is.

FLATOW: And so scientists are affected - or are still talking - troubled a bit as far as (unintelligible).

Ms. SOBEL: Yes, yes, and this new term has been given to Pluto: dwarf planet. But a dwarf planet is not a planet, and in astronomy there are dwarf stars which are stars and dwarf galaxies which are galaxies. So it's a term that no one can love - dwarf planet. But something -

FLATOW: Just the committee.

Ms. SOBEL: It's something -

FLATOW: (unintelligible) to be done by committee.

Ms. SOBEL: But now there'll be more committees. You'll see. It's not over.

FLATOW: Yeah? And so we haven't heard the last word on this.

Ms. SOBEL: No, absolutely not.

FLATOW: Who's the biggest proponent of bringing it back as a planet?

Ms. SOBEL: It's hard to say.

FLATOW: Are there a group of scientists?

Ms. SOBEL: Yes, there are hundreds of scientists who have expressed displeasure with the voted-upon definition.

FLATOW: If it remains as a dwarf planet, does that diminish its role in the solar system? I mean -

Ms. SOBEL: Well, not to a scientist who's interested in Pluto, certainly not. I think there was some real concern that if the status had been changed before the launch of the New Horizon spacecraft last January, people were afraid the mission might have even been canceled, but it's on its way now. There's no calling it back, which is a good thing. And in 2015, we'll finally find out what Pluto really looks like.

FLATOW: Yeah, 1-800-989-8255. We're talking with Dava Sobel, who is author of the recent released paperback The Planets, and just the cover itself is worth buying the book. It's just gorgeous, the graphics. Do you help choose that or all that's publisher who did this?

Ms. SOBEL: No, no. The brilliant jacket designer, Evan Gasney, did that.

FLATOW: What - and do you have a favorite planet?

MS. SOBEL: Yes, the Earth. I think it's only fair. It's the only planet that would have me. And it's really the best place to live.

FLATOW: Right.

Ms. SOBEL: But if I'm looking at the night sky, then I would say Venus would be my favorite. And if there's a telescope around, then it would be Saturn or Jupiter.

FLATOW: I think Venus just pops out there first. It's like the beacon in the west.

Ms. SOBEL: Yes, when it's there.

FLATOW: When it's there.

Ms. SOBEL: Yes.

FLATOW: Do you actually look at the planets through your own telescope?

Ms. SOBEL: I do.

FLATOW: Yeah?

Ms. SOBEL: I do. I'm very bad with equipment, though. I really - there's so much you can't see with the naked eye.

FLATOW: Right.

Ms. SOBEL: And astronomers, especially amateur astronomers, are so generous. If anybody wants to see the planets through a telescope, there's always an amateur group ready to have a public viewing night. And they would just love to show you something through their telescope.

FLATOW: You know, my fondest remembrance of a trip to Las Vegas, of all places, was out there by the Red Rock. There was a amateur viewing night. And I mean how long can you, you know, stay in Vegas? And you take a drive outside, and as my way back in, as the sun was setting, I just drove right into the parking lot and had the time of my life looking at, you know, a dozen telescopes.

Ms. SOBEL: Isn't it great? Yeah. And it's actually more fun for them when newcomers arrive and feel their excitement. They really love that.

FLATOW: Yeah, of course a lot of people have to get outside because you can't see a lot of, you know, horizon if you don't get up high enough to see things that are close to the horizon.

Ms. SOBEL: Right.

FLATOW: So it's a good deal.

Ms. SOBEL: Right, I thought you were talking about Vegas. People have to get out.

FLATOW: Well, there's so much light pollution now.

Ms. SOBEL: Yeah, yeah.

FLATOW: You know? That if you're not facing the right - you don't watch the west with the rising - you don't face the right direction, you're not going to see the planets.

Ms. SOBEL: Right.

FLATOW: They're going to be really drowned out. We're going to take a short break and come back and talk lots more with Dava Sobel, who is the author of The Planets. She's going to talk about why she's used some of her artistic knowledge, like talking about astrology when we're talking about the chapter on Jupiter. So it's interesting stuff. She took chances, as she said, in writing the book. We'll have her take a chance with you and your phone calls when we get back. Don't go away.

I'm Ira Flatow. This is TALK OF THE NATION: SCIENCE FRIDAY from NPR News.

(Soundbite of music)

FLATOW: You're listening to TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow.

We're talking with Dava Sobel, a science writer and author of Longitude in 1995 and now The Planets, out in hard cover and - last year, that was released in hard cover - this year out in soft cover, paperback, beautiful book. Our number, 1-800-989-8255.

Your chapter about Jupiter is titled Astrology. Why is that?

Ms. SOBEL: Astrology is certainly one of the ways people know the planets, and if you ask a group of people how many of you know your sign, almost every hand goes up.

FLATOW: Right.

Ms. SOBEL: So I didn't think I could leave that out. And astrology has certainly played an important part in the history of astronomy because most of the famous astronomers had to cast horoscopes as part of their work for their patrons. Galileo, Kepler, they all did that work. And so there's a shared history, and I made the astrology chapter about Jupiter because in astrology Jupiter is the greatest positive force.

And I worried about this a lot. Carl Sagan was really a mentor to me, and he worked so hard in his life to point out the fallacies of pseudoscience and astrology in particular. And of course as a science writer I'm supposed to say that it's just nonsense, and if you want to know your real connection to the universe, you should study astronomy and realize you're made of stardust, which is true. But still, the astrology is interesting historically, and I felt it legitimately belonged in the book. And my answer to Carl would have been it's for the purposes of public education.

FLATOW: Well, as another wonderful writer - double Pulitzer Prize writer - John Wilford of The New York Times once said to me, you got to have a little whimsy.

Ms. SOBEL: Yeah, yeah. Oh, I'm great fan of his.

FLATOW: Sure, so he - you know, there's an interesting way you to present and look at all these things. You actually drew a chart for the Galileo spacecraft, right?

Ms. SOBEL: Yeah. Well, I didn't do it, but I went to an astrologer to have it done. Galileo had done his own chart in his lifetime, so I had that analyzed. And then I had a chart done for the spacecraft, and it was just fun looking at the problems that that spacecraft had and comparing that to what was actually in its chart. If you remember, it had all sort of problems with its antenna because -

FLATOW: Right, as soon as it was launched it had them, right, right.

Ms. SOBEL: As soon - the antenna wouldn't open.

FLATOW: Right.

Ms. SOBEL: And then tape recorder was jamming. So it had all these communications problems. So you look on the chart, and there the planet Jupiter has a square or the worst possible aspect with the planet Mercury, the planet of communication. Now that's very entertaining.

FLATOW: Very whimsical.

Ms. SOBEL: Yes. So - but I was roundly attacked for talking about it at all and for saying that. I mean there were people who thought I was as earnest about astrology as I'd been about the Bible.

FLATOW: Wow.

Ms. SOBEL: So I -

FLATOW: So you took heat for that.

Ms. SOBEL: I did.

FLATOW: Yeah.

Ms. SOBEL: I still do.

FLATOW: Yeah.

Ms. SOBEL: But I would do it again.

FLATOW: Yeah.

Ms. SOBEL: And I actually really like that chapter. I think it works particularly well.

FLATOW: 1-800-989-8255. Let's see if we can get some calls in. Let's go to Robert in San Antonio. Hi, Robert.

ROBERT (Caller): Hi, how you doing this afternoon?

FLATOW: Hi, go ahead.

ROBERT: Okay, I had the privilege of listening to Longitude and The Planets, the audio book version, and I think that, you know, they're both steeped in poetry. The way The Planets was it came through beautifully in the audio book format, and I just wanted to make that comment.

Ms. SOBEL: Well, thank you. I'm really glad you liked it. I listened to it also. I thought she did a very good job of reading it.

ROBERT: Absolutely.

FLATOW: Thanks for calling. Have a good weekend.

ROBERT: Thank you.

FLATOW: 1-800-989-8255. Let's go to Cindy in Eau Claire, Wisconsin. Hi, Cindy.

CINDY (Caller): Hi, I just - I find it curious, also, that the entire zodiac is beautifully entiled in the floor of the Library of Congress in Washington, DC, and also in the University of Wisconsin, Madison, library entrance. It's on a whole wall, and it just seems curious to me.

Ms. SOBEL: Curious that it's there at all?

CINDY: Curious because there's so much negativity about the mystical or about the zodiac, the astrological aspect of things. I understand in Greek times that the word for astrology and astronomy was one word. They weren't separate.

FLATOW: Do you have a question, Cindy?

CINDY: Yes, I do. I called to ask about if the author has any comments about the planetoid or dwarf planet Charon orbiting - in a 50-year orbit between Saturn and Uranus? And also if there is - the second question is if she has -if you have any information or confirmation about a 12th planet (unintelligible) Samarian scholar called the 12th planet. It was a very highly elliptical, 3,000-year orbit. And I'll just hang up, thank you.

FLATOW: Thank you.

Ms. SOBEL: Well, Charon I'd -

FLATOW: She sounds very knowledgeable.

Ms. SOBEL: Yes. Charon is not included in my book because it's not quite a planet. It's even less of a planet than Pluto may be now, but it does figure in astrologers' charts. They definitely count it in. And the 12th - that 12th planet, no.

What was really interesting was the 10th planet which was for a long time called Xena and which really forced the issue of the planet definition because that body is larger than Pluto. So if Pluto was a planet, then Xena would have been, too. But it is not, and it has now gotten its official name of Eris, which convinces me that scientists still have a sense of humor.

FLATOW: They do. They do. Well, so anybody who can come up with Charmed and, you know, all those kinds of names for things, they do have a good sense of humor. I think one of our - the planet that has been in most view lately is, of course, I think Mars, considering there are rovers that are going around there sending back these great pictures.

Ms. SOBEL: Fantastic images, and the rovers just going on and on and on, far beyond their life expectancy.

FLATOW: Yeah, they're entering their third year - the three years now of their three month tour.

Ms. SOBEL: Right. This is why robots are so great.

FLATOW: Are they better than people, do you think, then for exploring space?

Ms. SOBEL: I think they are. I really do. I mean there's no question that they last longer, are cheaper to send, go to places that people will never be able to go. One of the things that I worry about with this Moon/Mars Initiative is when people are finished with the Moon and Mars, they're really finished.

FLATOW: Right.

Ms. SOBEL: And - whereas a robot can go to Pluto -

FLATOW: Right.

Ms. SOBEL: - and Neptune, and they're much more versatile. And yet people seem to need an astronaut in space from time to time just to feel a human response to the void, the greatness.

FLATOW: You know, I think that's true to a certain extent, but how many people know that there are astronauts right at this moment orbiting around us or care, even know, you know, know that?

Ms. SOBEL: That's true. It's not - it doesn't get the attention that it got in the early days.

FLATOW: You're showing your '60s influence. It was as exciting as the World Series.

Ms. SOBEL: It was so exciting.

FLATOW: In classrooms you turn on the radio and the PA system came on.

Ms. SOBEL: Right, everybody followed them.

FLATOW: Everybody followed them, and now no one even knows that they're there. What about the moons of Jupiter? You know, after - was WC - was Arthur C. Clarke prescient when he talked about 2001: A Space Odyssey and said go to Jupiter. Those moons have something special there.

Ms. SOBEL: Right, and he even mentioned Europa.

FLATOW: Yeah. Isn't that amazing.

Ms. SOBEL: Which is absolutely amazing. And now NASA thinks that maybe there might be something living or coming to life on Europa, which is why the Galileo spacecraft was intentionally destroyed.

FLATOW: Yeah.

Ms. SOBEL: In case someday it should go derelict and blunder into Europa and perhaps kill something there.

FLATOW: Let me see if I have one more call I can take. Let's go to Lucinda in Boise, Idaho. Hi, Lucinda.

LUCINDA (Caller): Hi, there.

FLATOW: Hi, there.

LUCINDA: Hi. I really had a - I'm fascinated by your discussion and the fact that there's so much great nature of whimsical ideas in astronomy and astrology. I have a question. I have a three-year-old granddaughter, and I would love to get her interested in the stars and the fact that there's a whole lot more than our neighborhood. Any suggestions for - other than, you know, going to planetariums - any suggestions for good books?

Ms. SOBEL: Oh, I know a nice book called There Once Was A Sky Full of Stars, but that won't teach you the constellations.

LUCINDA: Okay.

Ms. SOBEL: I'm afraid I don't know anything for children that young. But that's a very good question. And I will have to research that myself.

LUCINDA: Yeah, I've been looking and I've been having kind of a hard time finding something that will really motivate really young kids to get excited about being, you know, just sitting out in the back yard looking.

And luckily for us where I live, we can see the stars still, this week. Maybe not - some day it will be like the Bronx, I'm sure. But so far we can still see the stars.

FLATOW: Well, the Bronx has the Yankees so everybody else has the stars.

LUCINDA: Then there is that. There is - doesn't have a baseball team. Thank you.

FLATOW: Sorry to hear that. Thanks, Lucinda. Have a good weekend.

LUCINDA: Bye bye. You, too.

FLATOW: 1-800-989-8255. One more call from Bill in New Albany, Indiana.

BILL (Caller): Yes. Hello.

FLATOW: Hi, there.

BILL: I just wanted to say what a pleasure it is to speak with you, Ms. Sobel. Thank you for taking my call. I was wondering if you would comment about - and I apologize. It's been almost a year since I read the book and I haven't read it since then although I have read Longitude three or four times.

But the one chapter that has the woman writing the letters -

Ms. SOBEL: Yeah.

BILL: - about the discovery of either Neptune or Pluto, I was very interested in the way you brought the woman's influence in the scientific discoveries in that. I'm currently reading Galileo's Daughter and I really enjoy the way you incorporate women's influence and contributions into your works.

Ms. SOBEL: Thank you. It was about the discovery of Uranus and Neptune. And I did that as a letter from Caroline Herschel, who was the sister of William Herschel who discovered Uranus.

And then Caroline lived a very long life. She lived to be 98. So she was still alive when Neptune was discovered about 60 years later. And I had her write a letter to the only other woman in the world who had also discovered a comet. And that was Maria Mitchell, young American astronomer. And there's no evidence that they ever had any sort of correspondence. But that seemed the best way to handle that chapter.

FLATOW: Thank you, Bill, for calling.

BILL: Thank you very much.

FLATOW: You're welcome. Well, we're going to have to say goodbye, Dava. It's so always a pleasure to have you. You can come back any time you'd like, talk about the planets.

Ms. SOBEL: I'll take you up on that.

FLATOW: You know, when another little one is thrown out we'll give you a call.

Ms. SOBEL: Or if Pluto comes back.

FLATOW: You're right. You do give us a call.

Ms. SOBEL: I will call you.

FLATOW: You give us a call. You'll be right on talking about Pluto coming back. Dava Sobel, author of The Planets. You know her from Longitude, Galileo's Daughter, a terrific book. It was great the first time, even better the second time for another read. The Planets.

Thank you very much for taking time to be with us.

Ms. SOBEL: Thank you.

FLATOW: You're listening to TALK OF THE NATION: SCIENCE FRIDAY from NPR News.

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