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Astrophysicist Neil deGrasse Tyson

9 minute read
Gilbert Cruz

Once a planet, now a dwarf, Pluto has lodged itself in the American consciousness for three-quarters of a century. Astrophysicist Neil deGrasse Tyson, director of New York City’s Hayden Planetarium, explores the little guy’s allure in his new book The Pluto Files. He talked to TIME about demoting a planet, how he became one of America’s best-known scientists and how science will fare in the Obama Administration.

Why in the world do Plutophiles, which you make a pun on in your book title, even exist? What’s so special about Pluto?
All Plutophiles are based in America. If you go to other countries, they have much less of an attachment to either the existence or preservation of Pluto as a planet. Once you investigate that, you find out that Disney’s dog Pluto was sketched the same year the cosmic object was discovered. And Pluto was discovered by an American. So here you have a recipe for Americans falling in love with a planet that really is just a tiny ice ball. (See pictures of Mars.)

How did it get to be a planet in the first place?
There were high expectations that there was a planet of commensurate mass and size to Uranus and Neptune, orbiting behind Neptune. Scientists saw the path of Neptune around the sun, and they saw that it wasn’t quite following Newton’s laws of gravity. And so either Newton was wrong — though he’d been right for hundreds of years, so why assume that? — or there was some other mass out there that they hadn’t cataloged yet that was influencing the motion of Neptune. So that was the famous Planet X. And eventually, Clyde Tombaugh in Arizona discovered a planet, which got named Pluto. Not by an American, though, because an American would never have named it after a highly advertised, highly marketed laxative of the same name that was popular then.

So when did we figure out that Pluto is actually pretty minuscule?
What you do is, you look at the sky chart of stars and find the day when Pluto moves to intersect the light of a star. You set up observers across the earth, and you each get a different angle of view of Pluto intersecting the light of the star. And when you do this, you can actually map the size of an object in the solar system. Here’s what happened. They said, “O.K., here’s a star that’s going to get really close, and Pluto is surely going to blot out the light of the star.” Nope. The star just went right on by untouched. “Well, here’s a closer passing one.” Nothing. So for every star whose light was not blocked out, Pluto got smaller and smaller and smaller. People started getting suspicious in the 1970s and started thinking of it not as the ninth planet but as one of the vagabonds of the solar system. It was smaller than Earth’s moon. There are seven moons in the solar system bigger than Pluto. That doesn’t bode well if you’re trying to hang out in the ranks of planets. (See pictures of the Moon.)

You and your planetarium played a part in setting off this controversy. How did that come about?
We rebuilt the Hayden Planetarium between 1997 and 2000 at great expense. There was new science that needed to go in the facility, and you want the most reliable, longest-shelf-life science you can come up with. So I called in a panel of experts on the status of Pluto. And by the end of the night, it was clear that Pluto’s day was over and it was time to rethink the structure and the form of the outer solar system. Our exhibit was that way for a year, and nobody complained about it until it showed up in the New York Times, Page One: “PLUTO’S NOT A PLANET? ONLY IN NEW YORK.” That’s when all hell broke loose and the hate mail started.

So, how much hate mail did you get?
Let me be a little more honest in the word choice there. People felt very strongly and chose sides, and most of the hate mail was in fun.

There wasn’t any, “Stop talking smack about Pluto or I’m going to slash your tires”?
There were no threats of bodily harm. But there were tongue-in-cheek threats. And most of the schoolchildren were clearly disgruntled, pleading with me to put Pluto back where it belongs, as a planet.

See pictures of Earth from space.

See the top 50 space moments since Sputnik.

What, then, are the criteria for a planet?
In our exhibits, we abandoned the word planet as a useful word completely. We don’t organize by planet status. We organize by what objects look like compared to what other objects look like. So we look at the family photo of the solar system, and in it, you have the sun, which obviously is its own thing. Then you have the terrestrials — Mercury, Venus, Earth and Mars, all small, all rocky, all dense. Then you have the asteroid belt — craggy chunks of rock and metal — orbiting between Mars and Jupiter. Tens of thousands of them, likely hundreds of thousands of them. Then you have Jupiter, Saturn, Uranus and Neptune. They’re all big, all bulbous, all gaseous; they have rings; they all have many moons. That’s a group of objects. (See pictures of Mars.)

So when people say, “How many planets are there now?” I say, That’s the wrong question. Do not distract yourself over the answer to that question, because that question contains no science. Now I am partly to blame, as an educator, because to third-graders you teach the planets in sequence, and books celebrate this, and kids boast about memorizing planet names, thinking that they’ve accomplished something. But it would be much more effective intellectually if you tell me what Mercury, Venus, Earth and Mars have in common. Or why they are different. That’s a much more useful scientific inquiry than the recitation of planets in sequence. (See pictures of Earth’s mysteries and miracles.)

Is the way we teach kids about the universe in schools too simplistic, then?
Its not that it’s simplistic, but it doesn’t train the mind to think scientifically. There’s a lot of memorization that goes on in school. You memorize vocabulary words and all these sorts of things. But in science, memorization is not the ticket to understanding, and so, given that fact, why not teach it in a way that fosters insight into the form and structure of the solar system? (See pictures of animals in space.)

How does one get in your position, where you’re essentially the most famous astrophysicist in America and one of the most famous scientists in America? How does one even do that?
I’ve thought about that. I’ll tell you what it is. My first-ever interview for national television was in 1995 for NBC Nightly News. And I was interviewed about the discovery of the first planet outside of our own solar system. So, they came to the planetarium. I’m an easy date for them because I’m just up the street. I give them my best professorial reply. I talk about the Doppler shift and the measurement and the spectra, and I say, There’s not really a wobble — which is how it was commonly described — it was more like a jiggle; and I do a little jiggle with my hips. I rush home, watch the interview on TV, and hardly anything I said made it onto the clip. It only shows my hips jiggling. And I realized that I am visiting their medium. They’re not in my medium. My medium would be the lecture hall. But you’re going to put me on the evening news — now that’s a different way of communicating.

So I had my wife call out words, concepts, phrases that relate to the universe, and I stared in the mirror, and I delivered two or three sentences on each topic, in rapid fire. For each word, I would come up with two or three sentences that were informative, interesting and at best a little bit fun to listen to. I worked it. Then on the next interview, I handed them a sound bite. I essentially trained myself in sound bites. They can’t edit it; they don’t need to edit it. It’s self-contained. You just slot it right in. It fits in, and it makes you smile. And so, when that started, they kept coming back. And they never stopped.

With this new Administration, is there a sense in the scientific community that there is at least an attitudinal change coming to Washington with regard to science?
What’s driving attitudinal change is the fact that we need solutions to our energy crisis, and we need them fast. You can’t get those solutions from politics. You have to get them from scientists and engineers. So the value of science to the nation, I think, is currently being driven by our economic needs. But what people need to keep sight of is that the bigger value of science and technology to a nation is so that you can thrive as a nation going forward, so that you can thrive five years out, 10 years out, 20 years out. And investments in research and development today pay dividends on those time scales, not on the time scales of the re-election of politicians. Someone has to have foresight beyond their own election cycle.

See pictures of five nations’ space programs.

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