A Talk With the Man Who Would Banish Pluto

A New York Astronomer Kisses Pluto Goodbye

Neil de Grasse Tyson, director of the Hayden Planetarium, got up on stage the evening of Feb. 1. He had some bad news for the roughly 60 science buffs in a Museum of Natural History lecture hall.

“There’s this big argument raging about whether Pluto is indeed a planet,” he said. “I can tell you now that it’s got no hope. Just kiss it goodbye! On its way out! Just say, ‘Goodbye, Pluto, nice knowing you,’ because it’s not coming back as a planet. It’s a Kuiper Belt object , a Trans-Neptunian object , but it ain’t a planet. Get used to it.”

The banishment of Pluto from the solar system is not easy for some people to accept, but it is Mr. Tyson’s job to go with the facts. He has been spreading the word on Pluto’s demotion for some time now, in lectures and in his Natural History magazine column.

“Does Pluto match the other eight planets?” he said later that same night, in his small, windowless office at the Museum of Natural History. “The answer is flatly No , and that’s not debatable. The controversy comes out because Pluto spent 70 years as a planet in the hearts and minds of the public. So Pluto has sentimentality in its favor.”

Mr. Tyson was wearing a blue blazer, red planetary tie, khakis and tasseled loafers. There were paintings of eclipses on the walls.

“I’m close enough to the public sentiment to understand and empathize,” he said. “It has historical inertia in its favor: Why don’t we just grandfather it in, right? I can understand that. But when I put on my scientist hat, there’s just no question about it.”

On the shelves in his office were translations of his own books ( Merlin’s Tour of the Universe and Universe Down to Earth among them) and a stack of CD’s (Mozart, Buddy Guy).

“People had always knew that Pluto was a little weird,” he said. “But it wasn’t until the 1980’s where people had the courage to pluck Pluto out of the discussion of the other planets and include it in the discussion about comets and asteroids and other vagabonds of the solar system.”

In 1992, he said, two scientists were searching for objects in the outer solar system when they came upon a new class of objects–icy and cometlike, with orbits that were elliptical, like Pluto’s. “At that point,” he said, “you raise an eyebrow and you say, ‘This object looks more like Pluto than either of them look like any of the other planets, so maybe Pluto is a member of another class of objects, where it fits better.'”

It is simply time to stop making excuses for Pluto.

“If Pluto came to the distance of Earth, it would grow a tail,” he said. “What more do you want me to tell you? So Pluto is more like comets than it is anything else. People always knew it was icy, but you could brush that off and say, It’s so far out, of course it’s going to be icy.”

Now the question becomes: How do we tell the children?

“Pluto is by far the favorite planet of so many people,” the scientist said, “especially school kids. Why is it beloved? I don’t know. It’s the farthest planet, it’s the coldest, it’s the littlest–kind of like the underdog of the solar system. That’s my guess. It’s cute, it’s funny to say–sounds like it’s the punch line of a joke: ‘Where were you–on Pluto ? I was looking for you!’ Both Pluto the planet and Pluto the dog were invented by the Disney studio in 1930.”

Mr. Tyson was sitting still, with no fidgeting.

“The object will still be out there,” he said. “It’s not like we’re yanking it out of the solar system. It’s still there. But I think it’s hard, because there are people who their entire lives have only known there to be nine planets. You recite that as a schoolchild and now you have to subtract one away from that. Some will wonder, Oh, scientists are just changing their minds again–as though there’s no straight flow of knowledge. But in fact there is, and it’s a deeper understanding of how the solar system works. A richer understanding.”

Mr. Tyson got interested in the stars at the age of 10, when he looked through a friend’s binoculars. He went to the Bronx High School of Science, where he was captain of the wrestling team and editor of the physical science journal. He said he was underestimated. “It’s subtle,” he said. “People would go out of their way to tell me or call to my attention athletic opportunities, but not academic opportunities. I filled the stereotype of the black athlete.”

He went on to Harvard College, then got a master’s in astronomy at the University of Texas at Austin and a Ph.D. in astrophysics at Columbia University. Mr. Tyson, 40, is married, with a daughter, and he lives down by City Hall.

“Do you ever feel like you’re on a different plane?”

“You know when I think I’m on a different plane? When I buckle my seat belt and I see that other people don’t, because I’ve taken physics, and I know what happens in a collision. You study this. The transfer of momentum, the transfer of energy, the impulse of the car hitting the wall. So I put on a seat belt, and I see people come up with reasons why they should not, and I say to myself, ‘I’m on another plane.’ I walk up and down Broadway, you go into buildings, and two-thirds of the buildings do not have a 13th floor. It skips them. I’m on another plane. Somebody is afraid to put a 13th floor in a building, all right? There’s an old saying, ‘Lottery is a tax on people who don’t understand mathematics.’ O.K.? I’m on another plane. And by the way, I don’t like being there alone. I want to bring other people there with me, so they, too, can look at the lottery and see what a ridiculous waste of money it is.”

“Do you think there’s life in outer space?”

“The size of the universe is so immense and we’re so small a part of that, that it would be egotistical to suggest that we’re the only life in the universe.”

“What would you be satisfied with?”

“Any life at all, could be a little bacteria–because the step to go from no life to bacteria, as far as we know, is far greater than go from bacteria to a human being.”

He likened the change in Pluto’s status to the realization among paleontologists that the dinosaur known as brontosaurus had been put together wrong. “They found out the brontosaurus was the wrong head on the wrong body–and so there was no such thing as a brontosaurus anymore,” he said. “That classification has been retired. It’s unsettling, because you base your confidence in the world around you on the basis of unchanging knowledge–and if knowledge changes every day, you lose your footing on what is your assessment of reality. So I think that’s what makes people uncomfortable.”

Children nowadays have apatosaurus where brontosaurus used to be, just as they will soon learn that Neptune is the last planet in an eight-planet solar system.

“A whole new class of objects has been discovered,” said Mr. Tyson, sounding excited, “and now Pluto belongs to a family, whereas before it was an outcast. It may be the largest icy body in the solar system. It has a new status and I think it’s happier in that status. I’m a scientific optimist–so I would say that Pluto is enjoying its new status as the big man on campus and looking at Earthlings and saying, ‘Don’t be so cocky, because if you think I’m small compared to you, what do you think Jupiter is thinking of you?’ That difference is much bigger than Earth to Pluto.”

So he’s happy for Pluto, but sympathetic toward Clyde W. Tombaugh, the astronomer who dubbed it the ninth planet in 1930. “I know that he just died a couple years ago,” Mr. Tyson said. “His body’s barely cold, and here we are, taking the planet status away from the guy–but that’s what it is.”

By now, Mr. Tyson has put in a lot of time contemplating Pluto. “Pluto might have been lonely out there,” he said, “wondering where it came from, what its origins were. We all wonder that. ‘Where did I come from, where am I going? What is life about?’ And now with a whole family, I think it’s clear. Part of the Kuiper Belt of comets! It’s icy, just like everybody else. It orbits in a tipped path, just like everybody else in its class. So I think it would be happy. It found a home.”