Tip:
Highlight text to annotate it
X
ROBERT KRULWICH: Big news in the neighborhood. This is our solar system. And a couple of
years ago, almost everybody would have told you that orbiting our Sun you would find one,
two, three, four, five, six, seven, eight, nine planets; but, as of this past year, we've
got a tenth. Or do we?
MIKE BROWN: This will absolutely rewrite the "History of Astronomy" textbooks. There is
now a tenth planet out there.
ROBERT KRULWICH: When Mike Brown and his team at Caltech announced they'd discovered what
looked like a new planet, they did not give it a name. Names are bestowed by an international
commission of scientists. So, in the meantime, since they were looking at this little bright
light for more than year, they gave it a nickname.
MIKE BROWN: It had no name at all, so we had to call it something, so when we talked to
each other we'd know what we were talking about. So we always give things code names,
nicknames, and this one we codenamed Xena.
ROBERT KRULWICH: From...?
MIKE BROWN: From, of course, the TV show, Xena, Warrior Princess.
Of course, Xena has a satellite, which we had no choice but to call Gabrielle, which
is Xena's sidekick in the TV show.
ROBERT KRULWICH: No choice?
MIKE BROWN: No choice.
ROBERT KRULWICH: But in proper scientific circles, when scientists talk about this object
they use...
MIKE BROWN: ...the very unwieldy 2003UB313.
ROBERT KRULWICH: And it will stay 2003UB313 until the International Astronomical Union
officially decides that this is, indeed, a planetówhich by the way, they have not done.
They're not even close.
MIKE BROWN: We're in committee limbo, international committee limbo, which is about the worst
possible place you could imagine being.
ROBERT KRULWICH: But what exactly is the problem? It looks like a planet. I mean, it's round;
planets are round.
MIKE BROWN: Nothing's really round. The Earth has got a bulge in it, and Saturn is actually
quite squashed.
ROBERT KRULWICH: Okay, but Xena's round enough; and it's got a moon, which is very planet
like; and it orbits the sun. But it turns out, this matter is still debatable because
there's no precise scientific definition for "planet," and there hasn't been one for a
long time.
NEIL deGRASSE TYSON: Did you know that in 1801 a new planet was discovered orbiting
between Mars and Jupiter?
ROBERT KRULWICH: Neil deGrasse Tyson is director of New York's Hayden Planetarium.
NEIL deGRASSE TYSON: They called it Ceres. And they looked some more, and they found
another planet, and another and another. The count of planets in the early 1800s was greater
than it is today, thirteen planets in the solar system. And they kept looking, and the
numbers kept growing. And they were running out of names, and they realized that, rather
than counting new planets, they had discovered a new swath of real estate in the solar system
called the asteroid belt.
ROBERT KRULWICH: So Ceres became an unplanet, and was re-designated to a new class. And
it became the biggest asteroid.
NEIL deGRASSE TYSON: So we've been there before. We know how to demote something.
ROBERT KRULWICH: And that's exactly what he did to Pluto. When the Hayden Planetarium
reopened in the year 2000, Neil Tyson decided to de-planetize Pluto. "In our opinion," he
said, "Pluto is now an icy object that's different from the other planets."
NEIL deGRASSE TYSON: It's got enough ice, so that if you were to take Pluto and transport
it to where Earth is right now, the heat from the Sun would evaporate the ice and it would
grow a tail. And that's just no kind of behavior for a planet. We have words for things with
tails, they're called comets.
ROBERT KRULWICH: Same for Xena, another icy body that lives in the Kuiper Belt out beyond
Neptune. But a lot of people simply ignored Neil Tyson and the Hayden Planetarium and
stuck with the list they'd learned in school. Remember those planets in the right order?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.
NEIL deGRASSE TYSON: My very educated mother just served us nine pizzas.
MIKE BROWN: Martha visits every, Martha visits every Mondayómust be for Marsóand just stays
until noon, period. So there are two stupid things there. There's an "and" which is dumb,
except the "and" is right where the asteroid belt is. I don't know if that's an accident
or not. And then, I remember at the time, being in third grade, thinking that there's
something funny about Pluto if it's really just a period at the end of a sentence.
ROBERT KRULWICH: Sophisticated scientists and ordinary folks can't seem to get together
on this one. And Mike Brown, even though he discovered what could be the tenth planet,
has this advice for the scientists:
MIKE BROWN: What I favor is the "give up" approach, which is to say, the word planet
is not scientific, and it doesn't need to be. And as astronomers, we just need to get
over it.
NEIL deGRASSE TYSON: These are the Pluto files, okay? This is hate mail that I've gotten from
elementary school children. Handwritten letters saying, "Please, Dr. Tyson, what are you doing
with Pluto? What? That's our favorite planet!"
"You are missing Pluto. Please make a model of it. This is what it looks like. It is a
planet. Turn to the other page. A picture of Pluto."
"Dear Dr. Tyson, I think that Pluto is a planet for a lot of reasons, but you treat it like
nothing! So if you can, please leave it a planet. And if you don't, then I say it is.
And have a good day."