Why isn't Pluto a planet?
The Supermassive Podcast
Izzie Clarke
4.6 • 556 Ratings
🗓️ 30 June 2025
⏱️ 51 minutes
🧾️ Download transcript
Summary
Izzie and Dr Becky decided that little ol’ Pluto doesn’t get much attention anymore. So we’re giving the dwarf planet some time in the spotlight. Why isn't Pluto a planet? How small is it? And what makes it so unique?
Thank you to Prof Alan Fitzsimmons from Queens University of Belfast joining us episode.
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Transcript
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| 0:00.0 | Our moon is actually six times heavier than Pluto. |
| 0:04.0 | How many planets do you want? |
| 0:05.4 | We've got eight or do you want 13? |
| 0:07.7 | What is the criteria for being a planet? |
| 0:11.1 | And how does Pluto fall short? |
| 0:17.1 | Hello and welcome to the supermassive podcast from the Royal Astronomical Society with me, |
| 0:22.9 | science journalist Izzy Clark and astrophysicist Dr. Becky Smethurst. |
| 0:26.7 | We decided that little old Pluto doesn't get much attention anymore, so we're giving |
| 0:31.3 | the dwarf planet some time in the spotlight. |
| 0:34.3 | Yeah, it's about time. |
| 0:35.6 | It is, it is, yeah. |
| 0:36.9 | So in a moment, we'll hear from Alan |
| 0:38.9 | Fitzsimmons, Professor of Astronomy at Queen's University of Belfast to tell us more about Pluto |
| 0:44.1 | and why it was reclassified. And Dr. Robert Massey, the deputy director from the Royal |
| 0:49.2 | Astronomical Society, will take on listener questions later on in the show. So Becky, you get the opening |
| 0:55.1 | question this time. How did you feel when Pluto went from being a planet to a dwarf planet? |
| 1:01.2 | I mean, I was a little bit sad like everybody, right? I think we can't help but anthropomorphize |
| 1:05.9 | these things. We're like, I'm so sorry, Pluto. I don't like change. And yeah, I was, you know, still one of the generations that grew up, you know, being like, there's nine planets and, you know, what do you do now to all your demonic now that Pluto's not at the end and all this kind of thing. But I think, you know, these feelings are slightly irrational because they are just inanimate objects, you know. And the IAU, the International Astronautical Union, |
| 1:29.3 | they were trying to tidy up all these designations of objects that we have in the solar system. |
| 1:33.6 | The number of bodies that we knew about was growing as we detected more and more things |
| 1:37.5 | beyond the orbit of Neptune and also big things in the asteroid belt as well, like series. |
| 1:43.4 | And it was sort of just getting a little bit messy to be like, well, those are planets because we knew about those for ages, but those aren't planets because we just discovered them and they're a bit fun. Like, yeah, sorry, there's no more room. There's no more room. Yeah, you know, it was either we had nine planets or we had, you know, ever-growing list, which the nymonics also |
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