Meet the man who killed Pluto

But don't blame Caltech astronomer Mike Brown for just doing his job.

Producer's Note: As part of our first-ever "TechKnow: On the Road" traveling show, we shot on location at Caltech in Pasadena, Calif.

Dr. Mike Brown, a professor of planetary astronomy at the esteemed research institute, joined us to talk about his most well-known accomplishment—contributing to the declassification of Pluto as a planet—as well as his own discovery of a massive planetoid in our solar system.

The declassification of Pluto was just recently put into question during a debate at the Harvard-Smithsonian Center for Astrophysics and according to the debate results, Pluto is still a planet. Dr. Brown says that these debates happen often and the votes go both ways. He notes that the media is keener to cover these happenings when Pluto gets the title of planet back.

Dr. Brown tells TechKnow, “I think the public still feels very sentimental about Pluto.”

Our contributors were fascinated by Brown's work and his techniques and peppered the professor with question after question. The following is an extended, edited transcript of their discussion.

Dr. Mike Brown

Phil Torres, “TechKnow”: Dr. Brown, you’re probably best known as the man who killed Pluto. Why'd you do it?

Dr. Mike Brown: You know, the obvious answer is that [Pluto] really had it coming. If it wasn't me, somebody else was gonna do it and it just needed to happen.

PT: And what happened? Tell me the story.

MB: The short version of the story is that Pluto never should have been called a planet in the first place. It was really just a big mistake because everybody thought it was as big as Jupiter when it was first discovered. Now it's known just how small it really is—smaller than our moon. And there are thousands of other things out there just like it in our solar system. [There’s an] asteroid belt that's between Mars and Jupiter and we don't call any of the things in the asteroid belt planets. Although, people did back in 1801, but they got over it. Out beyond Neptune there’s this other belt of all these small bodies that are flitting around the outside edge of the planetary system.

PT: What is special about that belt?

MB: These objects are on the very outer edge of the solar system, and they have been in sort of cold storage for the last four and a half billion years. So if you can figure out what they're made out of, figure out where they came from, figure out why their orbits are the crazy orbits that they have—you are basically looking back at a fossil record of the beginning of the solar system.

Shini Somara, “TechKnow”: Our understanding of the solar system seems to really depend on where technology is at.

MB: That is absolutely true. The reason that we started finding these objects just in the last 15 years was because of the development of digital cameras—the same digital cameras that all of us now have in our pockets on our cell phone. Now we can take pictures of vast areas of the sky, very quickly process them, find the small things that are moving across the frame, track them down, go to the big telescopes which also didn't exist 20 years ago and really start to make progress understanding this region.

PT: All of this effort to look at the edge of our solar system. Why is that important?

MB: It’s really the key to understanding how our solar system put itself together, how the planets formed, how they rearranged. If you have 8 planets, it’s not enough to really be able to put the story together very well. But you have thousands and thousands of these small bodies—and so small bodies are in a sense like the blood spatter on the wall after some massive murder in the outer solar system. The planets have all been moved away, but [with] that “blood spatter” you can read exactly who did what to whom.

PT: So if Pluto isn't a planet, then what is it?

MB: The official term for what pluto is is a dwarf planet. I didn't come up with that one. I think it’s a pretty silly word, but that's what it is.

PT: What would you call it?

MB: Planetoid is actually a nicely serviceable word—it’s smaller than a planet, but kind of looks like a planet.

PT: When you came out with this announcement about Pluto, did you face much resistance within your field or in the public?

MB: I didn't really come up with an announcement about Pluto—this was a decision of the International Astronomical Union. I pushed hard to make sure they made the right decision. I had found an object that's more massive than Pluto, and so what part of the discussion was—what do we do with this object that I found? Is it a planet? Is it the 10th planet? If I had not stood up and said, no, this thing I found is not a planet, don't be ridiculous—and neither is Pluto—I think that really helped people, astronomers make the decision. Was there a lot of resistance? Sure. There still is. I got hate mail  from young children for many years. I don't get as much now because young children think it’s funny that they know Pluto is not a planet and their parents don't. So, the children are on board. I get obscene phone calls late at night. That started more recently, and it's always on like a Friday or Saturday night. So I'm fairly sure it’s the same children from whom I got  the hate mail, and they're now off in college at their first frat party and they think it'd be really funny to call me up and yell at me. I save them all, because they're hilarious. And there are definitely a very small but vocal set of scientists who don't like the idea, mainly because they studied Pluto and they feel like saying it’s not a planet means that it’s less important. I think that they are looking at things the wrong way. I think it's better to classify things correctly—and then let’s explain why Pluto’s [still] actually really quite an important thing to study.

PT: You also found the largest object in the solar system in the last 150 years. What was it?

MB: It’s the most massive thing—right now we don't know if it is bigger than Pluto or exactly the same size or a little bit smaller. Eris was the object that led to all this debate and eventual demotion of Pluto. It’s very far away, about three times further away than Pluto is right now, but it comes in really close. It’s got a moon around it and a surface covered in methane. It’s got nitrogen in its atmosphere, and most of that atmosphere is frozen. It’s this fascinating little world. I don't think the fact that its a dwarf planet makes it any less interesting.

SS: Are you expecting to find a larger planetoid than Eris at some point?

MB: Yes, it would shock me if Eris is the most massive thing out there.

SS: It seems like the more advanced our technology becomes, the larger our outer solar system seems to become as well.

MB: It's certainly true. In the next 10 years, we'll find many many objects driven by new telescopes that are coming online in South America that have even bigger cameras on them. I think we're gonna start to detect things even farther out.

Crystal Dilworth, “TechKnow”: I love the story of the de-classification of Pluto, because I think its a great example of how new information can really change the entire idea that a group of scientists have about something that they've taken for granted to be true for a really long time.

MB: The interesting part of the grumblings about Pluto not really being a planet started when Pluto was discovered, but they eventually got pushed to the side. Everybody knew that this was something that would be a very difficult public conversation to have. What finally made the discussion have to happen was this discovery of Eris—either there’s gonna be a 10th planet, or if you really wanted to make sense there would have to be 200 planets. Or there’s gonna be eight planets. Finally that forced astronomers to actually have a rational conversation about what to do. Classification matters—as scientists, this is the first thing we do when we are confronted with an observation of a new phenomenon that we don't know. We classify things, and we use that classification to figure out what questions to ask, how else to investigate it. If we had been aliens walking into the solar system for the first time, no alien would put Pluto with these other things. The aliens would say, you know, there’s terrestrial planets, and there’s giant planets, and there’s asteroid belts over here, and there’s the stuff outside there.

SS: It’s really impossible to imagine that we're the only life form. Do you ever think about discovering other life forms?

MB: I think a lot about the question. I don't think about discovering it [myself], but I think about the question a lot. I don't even think, the right question is, “Are there other life forms out there?” Because the answer has to be yes, there’s just no possible way that the universe could exist in such a way in its vastness that we are the only intelligent life form that developed. That would be crazy. The important question is: Is it common or rare? Are there intelligent life forms at every star that we look up at in the sky? Or in our galaxy, we’re the only ones and you have to go to the next galaxy so you can find the other one. We have no idea what the answer to that is. If you have the right conditions, there’s a 100 percent chance that you'll have life. We find answers to questions like that by looking in our own solar system.

Crystal Dilworth

CD: With all of this stress on scientific funding these days, what would you say are the most important reasons to continue funding your type of research?

MB: That's a good question because the stuff that I do is, it’s hard to imagine it’s ever gonna have practical applications. People ask, “Why should we even worry about these sorts of things at the outer edge of the solar system?” And the answer that I have is that this is exploration. We are a species inherently explorers, and I think always have been. And we are continuing to explore the outer edges of what we think of as our home. Our home used to be our village. And then it was our continent, and then we crossed the oceans and the entire Earth was our home. We went to the moon and could look back and feel like this is our home now. We're expanding those outer reaches through telescopes, through robots that go out through space, and we're gonna continue to do that. We're gonna continue to want to learn more and farther away and explore what's out there.

PT: How far away is your work looking at?

MB: The things that I have been finding and discovering—the typical distance is about 4 billion miles away. Eris is about 9 billion miles away. It's the most distant object that humans have ever seen in orbit around the sun, and the day that it was announced, a person just down the road here in Riverside and he found it with his backyard telescope. It’s big, it’s bright, it was relatively easy to see. It’s pretty small, because it’s really, really far away. But for me it’s still kinda close.


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