Jupiter's Cosmic Blueprint, White Dwarf Feasts & Chiron's Evolving Rings

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Andrew Dunkley: Hello, thanks for joining us. This is Space

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Nuts. My name is Andrew Dunkley, and we're

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here to talk astronomy and space science. And

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on this episode, we are going to look at a

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study into Jupiter's role in shaping

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our solar system. What shape is that?

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It's rhomboid. No, we don't know. we're also

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going to look at a, white dwarf star that's

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chowing down on a planetesimal. Sounds

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appetizing. observing a rapidly

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developing ring system, and it's not far

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away. And if we've got time, an exoplanet

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that in inverted commas may

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be a life candidate. That's all coming up on

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space nuts. 15 seconds. Guidance is

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internal. 10, 9.

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Ignition sequence start. space nuts. 5, 4,

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3, 2. 1, 2, 3, 4, 5, 5,

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4, 3, 2, 1.

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Jonti Horner: Space nuts.

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Andrew Dunkley: Astronauts report it feels good. And it's

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good to have Jonti Horner back with us again.

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Professor of astrophysics at the University

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of Southern Queensland. Hi, Jonti.

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Jonti Horner: Good evening. How are you going?

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Andrew Dunkley: I am well. Good to see you.

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Jonti Horner: Oh, it's good to be back. Although I'm

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admittedly a bit of a zombie, so I warn

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everybody, I've had less sleep than I should

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have done in the last couple of days because

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of the weather. we had some weather happen on

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Sunday, which led to the power here being

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knocked out for 24 hours during a mini heat

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wave. So I didn't get much sleep then. And

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then this morning I've got a colleague from

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Japan visiting, so I had to pick him, his

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wife and their two lovely daughters up from

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Brisbane Airport. So I've had six hours of

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driving today off the back of two nights of

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not much sleep. So if I seem less coherent

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than normal, and I appreciate I'm normally

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not that coherent to begin with, you know

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why, of course.

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Andrew Dunkley: Yes, we've all been there. we've had dreadful

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weather here too. But it hasn't been the

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extreme heat, it's been the extreme wind.

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I got woken up, last night about

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1am by the Fly, screens rattling. It

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was so windy. Yes, they, they were just

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shuddering. And I thought, I can't live with

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this.

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Jonti Horner: So I went outside.

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Andrew Dunkley: It was freezing cold, supposed to be late

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spring here, and I

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just jammed some wood chips

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into the. I just went off to the

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garden and grabbed some mulch and shoved it

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in the wind in, in the fly screens to stop

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them rattling.

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Jonti Horner: It worked.

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Andrew Dunkley: I've done it better during the day, but,

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well, that's just Been ridiculous.

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Jonti Horner: I know your parents. I mean having said that

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we had heat wave conditions and couldn't

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sleep because of the heat, I'm happ confess

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that I've had the wood serve on today because

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having had 36, 38 degrees so

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that's around 100 for our American friends

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last few days. Today has been a toasty kind

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of 15 degrees. and we've got a rain event

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happening. so we've had everything in the

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last week we've had kind of almost tornadic

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storms, we've had hailstones the size of your

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fists, we've had under a kilometer an hour

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gusts and now we've got random cold that

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makes me feel like I'm back in the uk. So

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yeah, all happening. And this is why

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Australia is an interesting place to live

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even to the extent that with the

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thunderstorms. We had got an email through

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yesterday that our wonderful observatory,

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Queensland's only professional astronomical

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observatory in Mount Kent was closed

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yesterday. We weren't allowed to go there

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because there was a bushfire within 10km of

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it that had been sparked by the lightning

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from the storms and fanned by the heat wave

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in a place that got lightning but no rain. So

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ah, it's all happening here.

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Andrew Dunkley: Yes, dry storms are not uncommon where I am.

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We we do get quite a few storms every year

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with lightning and thunder and nothing else.

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and they, yeah, they're very well known for

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sparking bushfires.

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Jonti Horner: Yeah.

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So while we're on the diversion of the

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weather, actually I'll apologize for Maya the

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dog chirping in the background but my

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partner's just got home. But we're also

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sitting here with an incredibly heartbreaking

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record, record breaking storm in the

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Caribbean. Yes, I know she's just come

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home. Thank you for joining me with the

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podcast Happy Dog. but yeah, there's

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borderline record breaking storm in the

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Caribbean which is going to be a Category 5

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hurricane hitting Jamaica and doing a, ah,

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hell of a lot of damage. And it's one of

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these that from a scientist point of view,

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fascinating watching it looking at the radar

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footage and all the satellite footage and on

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one hand you've got this thing of incredible

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exceptional beauty and on the other hand the

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devastation it's going to cause. So the

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people in the, in the firing line for that.

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Andrew Dunkley: Yeah, I saw the satellite images this

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afternoon. It is enormous.

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Jonti Horner: Yeah, you look at the false color one

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with the color of the clouds which is an

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indication of the severity of the storm and

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the shape and it's the kind of thing that you

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only see with the strongest storms we've ever

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seen, typically in the Pacific. So for this

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thing to not only be happening in the

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Atlantic, which is less common, but

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to be, you know, crosshairs on Jamaica,

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which has had a bit of a charmed life with

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some sacks of the high mountains that tend to

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bounce and go around a bit. This one looks

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like it's not so much going to bounce a

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splat.

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Andrew Dunkley: So yeah, when we were in Panama earlier

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this year, we did the Panama Canal and

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they were saying that they never get

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hurricanes ever.

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Jonti Horner: Too equatorial is my understanding. You need

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to be far enough away from the equator to get

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enough spin so. So it's very rare that you

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get storms getting right up to the equator

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because coriolis force and things like that.

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Andrew Dunkley: Yeah, yeah, it's interesting, isn't it?

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Very interesting. Okay, we better get

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on with what we came here to get on with. And

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we're going to start with a study that's

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been released into Jupiter's role in shaping

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the solar system. Now I do recall Fred

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mentioning that Jupiter, if Jupiter

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didn't exist we wouldn't. And this study

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basically adds a lot of fuel to that claim.

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Jonti Horner: It does. Now where Fred said,

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Fred and other people talk about if Jupiter

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didn't exist then we probably wouldn't. Ties

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into something that's a pretty big

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myth in science communication, Ansel in

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science papers and stuff, which is the idea

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of Jupiter shielding us from impacts. And my

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most favorite piece of research I ever did in

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my career is proving that to be a lot of

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cobblers and it's actually a lot more

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complicated. Jupiter throws things at us as

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well as protecting us. So I've always got a

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bit of an eye on any study that says, hey

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guys, if Jupiter wasn't there, neither would

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we. But this is a really interesting one that

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looks an entirely different aspect of

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Jupiter, which is the role that Jupiter

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played on the formation and evolution of the

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early solar system, the formation of the

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planets. And I've actually been teaching

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planet formation this week to my undergrad

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students. I've just, prior to recording this,

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had a two hour tutorial with them where I've

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been talking about planet formation and

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brought this story up because it

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really highlights the fact that when we

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often see in documentaries and the stuff we

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get taught at school, we get the impression

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that everything's solved, that we know the

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answers, that we know full well how the

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planets formed in microscopic detail and

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we've got everything figured out and the

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Reality is that we haven't. We have a really

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good broad picture and we're getting better

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and better at understanding the processes

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that went on. But there's still a lot to

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learn. And part of that is that while we've

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known the solar system since the year dot,

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we've only known other planetary systems for

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the last 30 years. And in reality we're still

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learning an awful lot about the planetary

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systems we find elsewhere. And learning about

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them is cool and all, but it also gives us

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insights that help us better understand our

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planetary system and how it formed. And that

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ties into this because the more we

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study those other planetary systems, the more

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we're getting observations of really

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beautiful things like planetary systems that

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are in formation, where you've got a

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protoplanetary disk. And we're getting these

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gorgeous images from things like the

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ALMA array, the Ataccama Large Millimeter

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Array that shows disks of planet

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forming material around stars with gaps in

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them and ripples in them and bands in them,

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and all these beautiful structures. And some

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of these have been previous astronomy.

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Picture of the days where this ties into the

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solar system is if you imagine that kind of

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stereotypical image of a

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protoplanetary disk, a disk of gas and dust

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around a young star like the sun, where

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material is feeding in through that disk to

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the star. So while the gas and dust is

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orbiting the star, there is this kind of

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sense of inward motion where the stars kind

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of nominating at the inner edge of the disk,

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materials falling in, and more material from

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outside flowing in to replace it. Yeah, and

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some of the models of the formation of the

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solar system struggle to make the terrestrial

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planets as a result of that. Because the

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material in the inner solar system is

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destined to fall onto M the star. And how do

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you stop that happening to let that material

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hang around to actually form into planets?

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Now it's been pretty well established for a

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long time that the first planet that formed

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in the solar system and got to a good size

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was Jupiter. And there's good reasons for

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that. It formed far enough away from the sun

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that the temperature was cold enough that the

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disk was rich in ice, which at, the

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distance the Earth is from the sun, all that

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ice would be gas. when you're forming solid

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objects, you need solid objects to feed from.

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And so when you've got a lot of ice, you've

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got a lot more solids. So things grow

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quicker, there's a lot more to eat. And it's

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only when you get to about 10 or 12 times the

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Mass of the Earth that You're massive enough

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to effectively start gobbling up the gas as

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well. So Jupiter formed beyond this point

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called the snow line, where there's a lot

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more solid material. It got to grow really

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quickly. It grew quicker than things further

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out because the further out you go, the

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slower things happen. So Jupiter was very

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much in the sweet spot, grew really quickly

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and eventually got big enough that it started

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clearing the gas and the dust it could gather

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the gas as well. And it opened up a gap in

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the disk. And that's very analogous to what

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we're seeing with these beautiful images from

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ALMA places like this. So the team of

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researchers behind this work have run some

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really in depth computer modeling of the

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formation of the solar system formation of

258
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Jupiter, and showed that when Jupiter opens

259
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up the gap in the disk, its gravity will

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also have an impact on the inner solar

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system. It'll effectively create the

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gravitational equivalent of speed bumps,

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creating areas where the dust that's

264
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spiraling inwards can pile up and be

265
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stopped from traveling further in.

266
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Effectively. It also creates

267
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a gap between the in run out of solar system

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that nothing crosses because if anything gets

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in that gap, Jupiter noms on it. And that's

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really interesting because some studies that

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have looked at primordial material we've

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found from in the solar system suggests that

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there is a bit of a chemical difference

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between material that formed in the inner

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solar system and material that formed in the

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outer solar system. So this gap

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dividing the two gives a natural way for that

278
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to happen. But the really big exciting result

279
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from this is really that modeling of

280
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the structure that Jupiter would have imposed

281
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on the inner solar system. These kind of pile

282
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up regions where you get more m dust and

283
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debris than normal, the structures that, that

284
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would carve out ripples in the disk

285
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effectively and how that would then

286
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contribute to the formation of the

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terrestrial planets. and therefore suggesting

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that not only did Jupiter help the

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terrestrial planets form by creating sweet

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spots where material could pile up, but it

291
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may also have had a really strong influence

292
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on the architecture of the inner solar system

293
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by setting where the planets would form,

294
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which then would go through a bit of a

295
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randomization phase as everything collides

296
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with each other. But it kind of possibly set

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the blueprint for the inner solar system. And

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therefore, if Jupiter hadn't formed where it

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did and how it did, the Earth would look

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very, very different and we might not be

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here.

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Andrew Dunkley: Yeah, it's truly fascinating. And

303
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when you look at other systems that

304
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we've discovered, exoplanet solar systems,

305
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ours is starting to look a little bit more

306
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unusual than normal. and

307
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Jupiter may be the reason.

308
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Jonti Horner: It could well be. And it's one of those

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things, I'm reminded of the Monty Python

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thing. I think it's in Life of Brian, where

311
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you've got that thing of we're all

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individuals. Yes, we're. No, we're not. I'm

313
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not. Every

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planetary system is going to be unique

315
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because it is influenced by

316
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such a wide variety of things going on. Even

317
00:12:01.240 --> 00:12:03.000
the stars that form in the local

318
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neighborhood, whittling it away from the

319
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outside, it all starts going on. But what

320
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we're seeing is there's a commonality among a

321
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lot of the planetary systems that we find

322
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that look very different to ours.

323
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The thing that gives us a little bit of pause

324
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though, is that we have these observational

325
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biases that make us more likely to find

326
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systems that are different to ours than we

327
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are to find systems like ours. And so you've

328
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always got that question of do we look

329
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unusual because we are unusual,

330
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or do we look unusual because we're not yet

331
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very good at finding places that look like

332
00:12:33.730 --> 00:12:35.550
home? and that's where colleagues of mine,

333
00:12:35.550 --> 00:12:37.660
like professor, Rob Wittenmayer, my colleague

334
00:12:37.660 --> 00:12:40.620
at unisq, have done really interesting

335
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work where what they

336
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do is look at what we found, but work

337
00:12:46.380 --> 00:12:49.260
out what doesn't exist

338
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based on what we haven't found yet. So they

339
00:12:52.100 --> 00:12:54.340
can start getting an estimate of how common

340
00:12:54.420 --> 00:12:57.060
our, ah, planetary systems like ours based on

341
00:12:57.060 --> 00:12:59.740
the fact we haven't found them yet. And it's

342
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a really kind of weird type of science where

343
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the absence of finding thing places limits on

344
00:13:05.500 --> 00:13:08.340
how common that thing is. So if you said

345
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that every star had a planet exactly like the

346
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Earth, on an orbit that's one year long that

347
00:13:12.740 --> 00:13:14.700
is exactly the same size as us and all the

348
00:13:14.700 --> 00:13:16.900
rest of it, then we can work out

349
00:13:16.900 --> 00:13:18.740
statistically, based on how good our

350
00:13:18.740 --> 00:13:21.260
telescopes are and our techniques are, how

351
00:13:21.260 --> 00:13:23.019
many of those planets we would have found.

352
00:13:23.019 --> 00:13:24.660
And we wouldn't have found anywhere near all

353
00:13:24.660 --> 00:13:26.900
of them because it's really hard to do. But

354
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we'd have found X amount. And the fact that

355
00:13:28.830 --> 00:13:30.830
we've only found a very small number smaller

356
00:13:30.830 --> 00:13:33.590
than that places an upper limit on how common

357
00:13:33.590 --> 00:13:36.200
things can be. So you get this perverse

358
00:13:36.360 --> 00:13:39.160
science where you get the observations

359
00:13:39.160 --> 00:13:40.800
that tell us what we found and what we've

360
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seen, but you can also put inferences on

361
00:13:43.600 --> 00:13:45.620
what isn't there and what is there based on

362
00:13:45.620 --> 00:13:47.900
what we haven't found yet, which allows you

363
00:13:47.900 --> 00:13:49.820
to put limits on how common things are that

364
00:13:49.820 --> 00:13:52.820
you couldn't really find very easily. Which,

365
00:13:52.820 --> 00:13:54.260
if that makes your head hurt. it makes my

366
00:13:54.260 --> 00:13:56.260
head hurt a little bit as well. But it's a

367
00:13:56.260 --> 00:13:59.180
really kind of clever use of the data we get

368
00:13:59.750 --> 00:14:01.750
to extrapolate further and draw more

369
00:14:01.750 --> 00:14:04.430
conclusions. And the net result of that is

370
00:14:04.430 --> 00:14:07.390
that the solar system is not hugely rare, but

371
00:14:07.390 --> 00:14:10.070
it's not common either. It's usual.

372
00:14:10.390 --> 00:14:11.690
And, that's really cool. And that probably

373
00:14:11.690 --> 00:14:13.370
extends to everything. Like I say, we're all

374
00:14:13.370 --> 00:14:16.370
individuals. The Earth, even though it's

375
00:14:16.370 --> 00:14:18.010
peeing it down outside at the minute, the

376
00:14:18.010 --> 00:14:20.570
Earth's actually a very dry planet. If you

377
00:14:20.570 --> 00:14:22.130
took all the water off the Earth and made a

378
00:14:22.130 --> 00:14:23.420
little blob of it next to the Earth, that

379
00:14:23.420 --> 00:14:25.860
blob would be fairly tiny. And everybody

380
00:14:25.860 --> 00:14:27.620
views the Earth as being very wet, but I view

381
00:14:27.620 --> 00:14:30.580
it as being very dry because water is such a

382
00:14:30.580 --> 00:14:33.500
common compound in the universe. It's made of

383
00:14:33.500 --> 00:14:36.020
the first and third most common atom. You put

384
00:14:36.020 --> 00:14:37.900
them together. Yet water waters everywhere.

385
00:14:37.900 --> 00:14:40.580
So for the Earth to be as dry as it is is

386
00:14:40.580 --> 00:14:42.660
telling you a lot about the uniqueness of the

387
00:14:42.660 --> 00:14:44.780
solar system. And maybe that's partially

388
00:14:44.780 --> 00:14:46.710
because of Jupiter. Not, necessarily

389
00:14:46.710 --> 00:14:48.550
shielding us from impacts, but preventing

390
00:14:48.550 --> 00:14:51.430
that icy material spiraling in, preventing

391
00:14:51.430 --> 00:14:54.390
us from becoming an ocean world. It's also

392
00:14:54.390 --> 00:14:56.150
partly down to the moon forming impact. The

393
00:14:56.150 --> 00:14:57.750
moon forming impact would have stripped a lot

394
00:14:57.750 --> 00:14:59.990
of the primordial Earth's water away because

395
00:14:59.990 --> 00:15:02.110
it walked as light and sits near the surface.

396
00:15:02.830 --> 00:15:05.430
So a lot about our Earth and a lot about the

397
00:15:05.430 --> 00:15:08.190
solar system is down to the random nature of

398
00:15:08.190 --> 00:15:11.110
the events around us. When we formed the moon

399
00:15:11.110 --> 00:15:13.470
forming impact, a nearby star going

400
00:15:13.470 --> 00:15:15.750
supernova and lacing our solar system with

401
00:15:15.750 --> 00:15:17.840
radioactive aluminium. Things like this.

402
00:15:17.840 --> 00:15:19.400
There's all these oddities that made our

403
00:15:19.400 --> 00:15:22.200
solar system unique, but if those

404
00:15:22.200 --> 00:15:23.720
hadn't happened, other things would have

405
00:15:23.720 --> 00:15:25.040
happened and we'd have still ended up with

406
00:15:25.040 --> 00:15:26.840
something unique because of other random

407
00:15:26.840 --> 00:15:27.600
things happening.

408
00:15:28.320 --> 00:15:30.440
It's all fascinating and I just love this

409
00:15:30.440 --> 00:15:30.800
stuff.

410
00:15:31.120 --> 00:15:33.440
Andrew Dunkley: Yeah. And it adds more and more weight to the

411
00:15:33.440 --> 00:15:35.840
theory that we are just a freak accident.

412
00:15:36.000 --> 00:15:36.560
Jonti Horner: Yes.

413
00:15:37.040 --> 00:15:39.040
Andrew Dunkley: And probably a one off in the universe.

414
00:15:39.760 --> 00:15:41.920
That's one argument. So, yeah,

415
00:15:42.560 --> 00:15:45.410
who knows if, if we find a

416
00:15:45.410 --> 00:15:47.330
solar system just like ours, with a planet

417
00:15:47.330 --> 00:15:50.120
just like ours, orbiting a

418
00:15:50.440 --> 00:15:53.080
star just like ours. That would be

419
00:15:53.720 --> 00:15:56.680
the, you know, one of the greatest

420
00:15:56.680 --> 00:15:58.560
discoveries in astronomical history, I

421
00:15:58.560 --> 00:16:01.440
imagine. But no, we do that.

422
00:16:01.440 --> 00:16:02.960
Jonti Horner: We would have to get in touch with the planet

423
00:16:02.960 --> 00:16:04.720
builders at Magrathea and demand that money

424
00:16:04.720 --> 00:16:06.120
back. Because we thought we had a limited

425
00:16:06.120 --> 00:16:06.600
edition.

426
00:16:06.760 --> 00:16:09.350
Andrew Dunkley: Yes, yes. weren't they the white mice? Was

427
00:16:09.350 --> 00:16:10.270
that the white mice?

428
00:16:10.350 --> 00:16:11.600
Jonti Horner: Yes, it was.

429
00:16:11.600 --> 00:16:13.320
Andrew Dunkley: Yeah. All right, if you want to read all

430
00:16:13.320 --> 00:16:15.880
about it, you can find, the paper,

431
00:16:16.540 --> 00:16:19.240
which was published in the journal Science

432
00:16:19.400 --> 00:16:20.040
Advances.

433
00:16:23.000 --> 00:16:25.960
Jonti Horner: Roger, your labs are here. Also space nuts.

434
00:16:26.180 --> 00:16:28.350
Andrew Dunkley: now, Jonti, let's move on to our next story.

435
00:16:28.430 --> 00:16:31.260
And this one is about a planetismal,

436
00:16:32.190 --> 00:16:35.110
that appears doomed. According to the, paper

437
00:16:35.110 --> 00:16:37.190
I'm reading, it's a white dwarf that's

438
00:16:37.190 --> 00:16:39.790
chowing down very, very hungry, hungry

439
00:16:39.790 --> 00:16:40.990
individual is this one.

440
00:16:41.790 --> 00:16:44.270
Jonti Horner: It is. So just to remind the audience, a

441
00:16:44.270 --> 00:16:47.030
white dwarf is the kind of little husk

442
00:16:47.030 --> 00:16:48.990
that's left after a cell like our sun comes

443
00:16:48.990 --> 00:16:51.430
to the end of its life, burns all its

444
00:16:51.430 --> 00:16:53.870
hydrogen, becomes a red giant, and then

445
00:16:53.870 --> 00:16:55.750
eventually blows off its outer layers. And it

446
00:16:55.750 --> 00:16:58.110
leaves a big chunk of the star's mass

447
00:16:58.510 --> 00:17:00.350
compressed into an object about the size of

448
00:17:00.350 --> 00:17:03.270
the Earth. That whole process will

449
00:17:03.270 --> 00:17:05.870
have a fairly hefty impact on the

450
00:17:05.870 --> 00:17:07.870
planetary system that star's got around it.

451
00:17:08.230 --> 00:17:09.710
And of course, as we just discussed, we now

452
00:17:09.710 --> 00:17:11.670
know that pretty much every star has planets.

453
00:17:12.150 --> 00:17:14.310
The expectation is that when the sun reaches

454
00:17:14.310 --> 00:17:16.350
this stage, unfortunately it's in about 7

455
00:17:16.350 --> 00:17:18.060
billion years, so nothing to worry about.

456
00:17:18.060 --> 00:17:20.700
Immediately it will swell up and it will

457
00:17:20.860 --> 00:17:23.020
chow down on Mercury and chow down on Venus.

458
00:17:23.020 --> 00:17:25.820
They'll just be swallowed up and gone. Yeah,

459
00:17:25.820 --> 00:17:27.700
There is some debate over whether the Earth

460
00:17:27.700 --> 00:17:30.300
will be swallowed up or will survive. Just

461
00:17:31.100 --> 00:17:33.230
all the models of star, evolution suggest

462
00:17:33.230 --> 00:17:35.190
that the sun will swell up to be about the

463
00:17:35.190 --> 00:17:37.510
radius of the Earth's orbit. But whether the

464
00:17:37.510 --> 00:17:39.390
Earth is there to nominal or not is still

465
00:17:39.390 --> 00:17:41.870
open for debate. It may be that the loss of

466
00:17:41.870 --> 00:17:44.590
mass from the sun in the time before may just

467
00:17:44.590 --> 00:17:46.670
mean that the Earth nudges far enough away to

468
00:17:46.670 --> 00:17:48.510
survive as a burnt husk rather than be

469
00:17:48.510 --> 00:17:51.430
devoured. It still would be ideal

470
00:17:51.430 --> 00:17:53.270
to be around when that wouldn't be pleasant.

471
00:17:53.270 --> 00:17:54.630
I mean, that said, the Earth is going to

472
00:17:54.630 --> 00:17:56.870
become uninhabitable a lot sooner than that

473
00:17:56.870 --> 00:17:58.750
because the Sun's getting brighter and the

474
00:17:58.750 --> 00:18:01.550
Earth's oceans will boil and it'll all go

475
00:18:01.550 --> 00:18:04.460
downhill. But after all that process

476
00:18:04.460 --> 00:18:06.700
happens when the sun sheds its outer layers,

477
00:18:07.020 --> 00:18:09.380
that'll have a pretty cataclysmic event on

478
00:18:09.380 --> 00:18:12.060
the planets and the debris that are left. So

479
00:18:12.060 --> 00:18:14.020
suddenly the sun goes on the ultimate kind of

480
00:18:14.020 --> 00:18:16.860
weight loss kick loses mass. And that

481
00:18:16.860 --> 00:18:18.860
will mean that all of the objects going

482
00:18:18.860 --> 00:18:21.300
around the sun will be held less strongly.

483
00:18:21.300 --> 00:18:23.020
And so therefore their orbits will move

484
00:18:23.020 --> 00:18:25.700
outwards because the gravity pulling them in

485
00:18:25.700 --> 00:18:28.580
gets weaker. Now, if you suddenly Press the

486
00:18:28.580 --> 00:18:30.960
button and vanished half of the mass of the

487
00:18:30.960 --> 00:18:33.560
Sun. What had happened is that the speed that

488
00:18:33.560 --> 00:18:35.720
any of the objects are going in their orbit

489
00:18:35.880 --> 00:18:37.680
will be too quick for that orbit to be

490
00:18:37.680 --> 00:18:40.520
circular. So at that instant, at that

491
00:18:40.520 --> 00:18:43.040
point, they'd now be at their new perihelion,

492
00:18:43.040 --> 00:18:44.560
they'd be at their closest point to the sun,

493
00:18:44.560 --> 00:18:45.960
and they'd all move out onto much more

494
00:18:45.960 --> 00:18:48.520
elongated orbits with a longer orbital

495
00:18:48.520 --> 00:18:51.200
period, but orbits that would then cross one

496
00:18:51.200 --> 00:18:53.640
another. So if you imagine you lose half of

497
00:18:53.640 --> 00:18:56.320
the Sun's mass, Jupiter moves onto an orbit

498
00:18:56.320 --> 00:18:58.480
where its perihelion is 5 au from the sun,

499
00:18:58.480 --> 00:19:00.840
but its aphelion could be 15 au from the Sun.

500
00:19:01.400 --> 00:19:03.760
Saturn at the same time would have perihelion

501
00:19:03.760 --> 00:19:06.120
at 10 au and aphelion at say 20 au. And I'm

502
00:19:06.120 --> 00:19:08.440
making the numbers up a bit here. So suddenly

503
00:19:08.440 --> 00:19:11.199
Jupiter and Saturn are on orbits that

504
00:19:11.199 --> 00:19:14.120
cross one another. Their orbits

505
00:19:14.120 --> 00:19:16.520
will probably still have the same ratio of

506
00:19:16.520 --> 00:19:19.400
orbital periods, so 12 years to 29 years. But

507
00:19:19.400 --> 00:19:21.290
they'd scale up to be something like, I don't

508
00:19:21.290 --> 00:19:23.650
know, 30 to 70 or something like that,

509
00:19:23.970 --> 00:19:25.570
because they've both moved out by the same

510
00:19:25.570 --> 00:19:27.650
amount. But suddenly you've got these planets

511
00:19:27.650 --> 00:19:29.450
that are on orbits that cross each other and

512
00:19:29.450 --> 00:19:32.130
therefore can really strongly interact. They

513
00:19:32.130 --> 00:19:33.890
can stir everything else up because all of

514
00:19:33.890 --> 00:19:35.570
the objects in the asteroid belt, all of the

515
00:19:35.570 --> 00:19:37.330
objects beyond Neptune, this happens to

516
00:19:37.330 --> 00:19:39.770
everything. Now the mass loss is a bit more

517
00:19:39.770 --> 00:19:42.330
gradual than that in actuality. So what

518
00:19:42.330 --> 00:19:44.370
happens is you get the orbit spiraling out,

519
00:19:44.370 --> 00:19:46.170
but getting perturbed, being made more

520
00:19:46.170 --> 00:19:48.640
eccentric. You've also got these objects

521
00:19:48.640 --> 00:19:51.240
moving through the headwind of possibly half

522
00:19:51.240 --> 00:19:53.200
a solar mass of material being blown

523
00:19:53.200 --> 00:19:55.560
outwards. That provides friction and so

524
00:19:55.560 --> 00:19:57.720
causes them possibly to spiral inwards a bit.

525
00:19:58.520 --> 00:20:00.760
Causes Jupiter potentially to gather mass as

526
00:20:00.760 --> 00:20:03.400
it numbs on all that gas that's going out. At

527
00:20:03.400 --> 00:20:04.960
the same time, its atmosphere is probably

528
00:20:04.960 --> 00:20:07.360
being blasted away by all this wind blowing

529
00:20:07.360 --> 00:20:10.280
past. All of this complexity means

530
00:20:10.280 --> 00:20:12.200
that you couldn't predict with absolute

531
00:20:12.200 --> 00:20:14.080
certainty what the solar system would look

532
00:20:14.080 --> 00:20:16.920
like at the end of this, but certainly

533
00:20:16.920 --> 00:20:19.320
there'd be a period of chaos. A lot of stuff

534
00:20:19.320 --> 00:20:21.800
would survive, but it would survive on orbits

535
00:20:21.800 --> 00:20:24.520
that are now much more unstable. So you get a

536
00:20:24.520 --> 00:20:26.570
lot of material flung inwards and, some of

537
00:20:26.570 --> 00:20:29.170
that will be flung inwards far enough for it

538
00:20:29.170 --> 00:20:31.370
to impact on the Earth sized object in the

539
00:20:31.370 --> 00:20:33.700
middle and, for the white dwarf to get a

540
00:20:33.700 --> 00:20:36.300
snack. Now all that's expected to happen

541
00:20:36.300 --> 00:20:38.860
really early on. And over time everything

542
00:20:38.860 --> 00:20:41.530
stabilizes out, things get flung around and

543
00:20:41.530 --> 00:20:44.250
clean up happens a bit like the

544
00:20:44.250 --> 00:20:45.730
solar system. You know, we were talking early

545
00:20:45.730 --> 00:20:47.170
on about the early stages of planet

546
00:20:47.170 --> 00:20:49.090
formation. Everything gets flung around and

547
00:20:49.090 --> 00:20:51.210
by the time you get to now, four and a half

548
00:20:51.210 --> 00:20:52.770
billion years down the road, it's fairly

549
00:20:52.770 --> 00:20:55.210
quiet. There's a bit going on, but most of

550
00:20:55.210 --> 00:20:57.730
the drama's finished. So the

551
00:20:57.730 --> 00:20:59.730
expectation is you'd see white dwarfs that

552
00:20:59.730 --> 00:21:02.450
are very young occasionally eating things

553
00:21:02.450 --> 00:21:04.650
because things get flung in and they get a

554
00:21:04.650 --> 00:21:06.780
bit of a snack. And the material from that

555
00:21:06.780 --> 00:21:08.820
snack will be spattered over the surface of

556
00:21:08.820 --> 00:21:10.980
the white dwarf and be visible in its

557
00:21:10.980 --> 00:21:13.620
spectrum as anomalous added

558
00:21:14.100 --> 00:21:16.420
solid material, heavy elements.

559
00:21:17.140 --> 00:21:19.300
But that signal would only last a short time

560
00:21:19.300 --> 00:21:21.220
because the outer layer of the white dwarf is

561
00:21:21.220 --> 00:21:24.220
kind of a hydrogen soup and heavier elements

562
00:21:24.220 --> 00:21:27.140
would sink down. So any given time you'd eat

563
00:21:27.140 --> 00:21:29.660
something. The evidence for that meal would

564
00:21:29.660 --> 00:21:31.740
only remain for a few tens of thousands of

565
00:21:31.740 --> 00:21:34.650
years, SOPs before it goes away. Okay, so

566
00:21:34.650 --> 00:21:36.530
the fact is we've seen some white dwarfs

567
00:21:36.530 --> 00:21:38.810
which have these anomalous heavy element

568
00:21:38.810 --> 00:21:41.010
readings in their atmospheres. We can tell

569
00:21:41.010 --> 00:21:42.690
they're eating stuff, but typically they're

570
00:21:42.690 --> 00:21:45.450
young. So you'd expect that.

571
00:21:45.930 --> 00:21:48.010
The quirky thing here is that this white

572
00:21:48.010 --> 00:21:49.850
dwarf, which goes by the name of

573
00:21:49.850 --> 00:21:52.820
lspm, which I think is a survey name,

574
00:21:52.820 --> 00:21:54.010
m followed by

575
00:21:54.010 --> 00:21:57.770
J020733331.

576
00:21:58.330 --> 00:22:00.210
So that's a coordinate on the sky. So that's

577
00:22:00.210 --> 00:22:01.690
telling you where in the sky this is. It's

578
00:22:01.690 --> 00:22:04.390
catalog number. Yeah, this thing is an old

579
00:22:04.390 --> 00:22:06.310
white dwarf. It's thought to be about 3

580
00:22:06.310 --> 00:22:08.350
billion years old. So in other words, the

581
00:22:08.350 --> 00:22:11.230
star that formed it died 3

582
00:22:11.230 --> 00:22:13.510
billion years ago and it's been sitting there

583
00:22:13.510 --> 00:22:16.390
minding its own business. That's old enough

584
00:22:16.390 --> 00:22:18.070
that you'd expect everything to have calmed

585
00:22:18.070 --> 00:22:20.910
down around it. But what the new

586
00:22:20.910 --> 00:22:23.870
observations have shown is evidence of

587
00:22:23.870 --> 00:22:25.870
13 different heavy elements,

588
00:22:26.670 --> 00:22:28.750
including carbon, chromium,

589
00:22:29.980 --> 00:22:32.220
strontium, titanium, a lot of these different

590
00:22:32.220 --> 00:22:35.100
elements, roughly in the kind of abundance as

591
00:22:35.100 --> 00:22:37.630
you'd see on the Earth, added, to this white

592
00:22:37.630 --> 00:22:40.230
dwarf's atmosphere. So it's

593
00:22:40.230 --> 00:22:42.350
obviously just had a meal and we know it's a

594
00:22:42.350 --> 00:22:44.470
case of just had a meal rather than it's been

595
00:22:44.470 --> 00:22:47.190
a leftover from a long time ago, because this

596
00:22:47.190 --> 00:22:49.150
stuff will sink and disappear over the next

597
00:22:49.150 --> 00:22:52.110
few tens of thousands of years. So what

598
00:22:52.110 --> 00:22:54.190
that means is that this white dwarf

599
00:22:55.020 --> 00:22:57.380
has just had a snack. Now it might have had

600
00:22:57.380 --> 00:23:00.220
that snack 30,000 years ago, or it

601
00:23:00.220 --> 00:23:03.020
may still be in the process of eating as

602
00:23:03.020 --> 00:23:05.820
we speak. Now what the team have been able to

603
00:23:05.820 --> 00:23:08.340
do is look at the amount of material you'd

604
00:23:08.340 --> 00:23:10.140
need to give the strength of signal you've

605
00:23:10.140 --> 00:23:12.080
got in the spectrum of the star. And, what

606
00:23:12.080 --> 00:23:14.320
they've calculated is that to get this amount

607
00:23:14.320 --> 00:23:17.080
of material you'd need to eat an asteroid

608
00:23:17.800 --> 00:23:19.960
about 200 kilometers in diameter.

609
00:23:20.760 --> 00:23:22.520
So that's comparable to some of the larger

610
00:23:22.520 --> 00:23:24.200
asteroids in the asteroid belt, but not the

611
00:23:24.200 --> 00:23:26.920
largest by any means. It's within the bounds

612
00:23:26.920 --> 00:23:28.680
of possibility of what we see here at home.

613
00:23:29.080 --> 00:23:31.160
But the real question is why is it eating it

614
00:23:31.160 --> 00:23:33.520
now? Why is this happening now when you'd

615
00:23:33.520 --> 00:23:35.200
expect the system to have had plenty of time

616
00:23:35.200 --> 00:23:37.560
to calm down? What

617
00:23:37.960 --> 00:23:40.760
it suggests to me, and it suggests in the

618
00:23:40.760 --> 00:23:42.960
paper, it suggests in the articles about this

619
00:23:42.960 --> 00:23:45.240
as well, is that the only way you can get

620
00:23:45.240 --> 00:23:48.070
something eating this late, after 3 billion

621
00:23:48.070 --> 00:23:50.830
years have passed, is if you've still got a

622
00:23:50.830 --> 00:23:53.310
number of planet mass objects in the system

623
00:23:53.310 --> 00:23:56.230
serving things up, which is what we've got

624
00:23:56.230 --> 00:23:57.910
in the solar system. If we look at the inner

625
00:23:57.910 --> 00:24:00.270
solar system, fragments of comets and

626
00:24:00.270 --> 00:24:02.070
asteroids are falling onto the sun all the

627
00:24:02.070 --> 00:24:04.350
time. We've got near Earth asteroids, short

628
00:24:04.350 --> 00:24:06.390
period comets and long period comets whizzing

629
00:24:06.390 --> 00:24:08.760
around. And, they're being bounced around by

630
00:24:08.760 --> 00:24:10.480
the planets. Jupiter's throwing a lot of

631
00:24:10.480 --> 00:24:12.920
stuff away. Their orbits are constantly

632
00:24:12.920 --> 00:24:15.800
getting tweaked. And so therefore the sun

633
00:24:15.800 --> 00:24:18.640
is still getting this rain of solid material

634
00:24:18.640 --> 00:24:20.880
falling on it as a result of the planets

635
00:24:20.880 --> 00:24:23.560
stirring things up. Even though the solar

636
00:24:23.560 --> 00:24:25.760
system mostly quietened down, the planets are

637
00:24:25.760 --> 00:24:28.320
still injecting material to the inner solar

638
00:24:28.320 --> 00:24:30.760
system, which is why we're getting meteorites

639
00:24:30.760 --> 00:24:32.400
and it's why the sun occasionally gets to

640
00:24:32.400 --> 00:24:35.120
numb some stuff. The idea here is

641
00:24:35.120 --> 00:24:37.400
that this star reached the end of its life.

642
00:24:37.400 --> 00:24:40.260
Puff dots with its outer layers. You have

643
00:24:40.260 --> 00:24:42.260
this really chaotic period where everything

644
00:24:42.260 --> 00:24:44.820
had got stirred up, then it settled down. But

645
00:24:44.820 --> 00:24:46.660
because you still got planet mass objects

646
00:24:46.660 --> 00:24:49.020
there, they're still bouncing around what

647
00:24:49.020 --> 00:24:51.620
debris is left. And we're just catching this

648
00:24:51.620 --> 00:24:54.460
white dwarf just at the right time, when

649
00:24:54.460 --> 00:24:56.740
another asteroid has been flung inwards close

650
00:24:56.740 --> 00:24:59.100
enough to be torn apart by the star's gravity

651
00:24:59.260 --> 00:25:01.900
and to give it a snack. So in other words,

652
00:25:02.220 --> 00:25:04.460
seeing this snack happening this late in the

653
00:25:04.460 --> 00:25:07.060
life of this white dwarf is fairly strong

654
00:25:07.060 --> 00:25:09.500
evidence that planets survived the death of

655
00:25:09.500 --> 00:25:12.140
its star, have lived there for 3 billion

656
00:25:12.140 --> 00:25:14.460
years, which a is really cool in of itself.

657
00:25:14.460 --> 00:25:17.380
But it also means that here is a star that we

658
00:25:17.380 --> 00:25:19.860
should look at when the Gaia data release

659
00:25:19.940 --> 00:25:22.500
comes next year. Gaia Dr. AH4,

660
00:25:22.980 --> 00:25:24.780
which will have been measuring this star's

661
00:25:24.780 --> 00:25:26.460
position on the sky. And if there Are planets

662
00:25:26.460 --> 00:25:28.220
there, we'll be able to detect the wobble and

663
00:25:28.220 --> 00:25:31.100
confirm them. So it's also holding up a flag

664
00:25:31.100 --> 00:25:33.760
to exoplanet people saying,

665
00:25:33.920 --> 00:25:36.520
hey, folks, here's a target for you to look

666
00:25:36.520 --> 00:25:38.320
at when the data release comes out where you

667
00:25:38.320 --> 00:25:39.840
might be able to find some planets, because

668
00:25:39.840 --> 00:25:42.240
we think there's a smoking gun here that the

669
00:25:42.240 --> 00:25:44.600
planets are feeding the white dwarf, giving

670
00:25:44.600 --> 00:25:46.160
it little snacks every now and again.

671
00:25:47.120 --> 00:25:49.040
Andrew Dunkley: Okay, wow. All right.

672
00:25:49.040 --> 00:25:51.950
so are there many white dwarf

673
00:25:52.030 --> 00:25:54.830
stars out there? What, do they, sort of,

674
00:25:55.870 --> 00:25:58.560
percentage wise, inhabit the star field?

675
00:25:58.720 --> 00:26:01.480
Jonti Horner: There would be a fair few of them. So the

676
00:26:01.480 --> 00:26:03.600
more massive a star is, the shorter its life

677
00:26:03.600 --> 00:26:05.850
is. And, that's a really rapid function.

678
00:26:06.330 --> 00:26:08.860
Where that works is, if your star's more

679
00:26:08.860 --> 00:26:11.420
massive, its gravitational pull is stronger,

680
00:26:11.980 --> 00:26:14.940
so its ability to pull material into

681
00:26:14.940 --> 00:26:17.900
the middle of the star is higher, which means

682
00:26:17.900 --> 00:26:19.780
that that star's got to give off a lot more

683
00:26:19.780 --> 00:26:21.900
energy to balance that gravitational pull.

684
00:26:21.900 --> 00:26:24.140
And so stars in the main sequence part of

685
00:26:24.140 --> 00:26:26.690
their life are in equilibrium. The radiation

686
00:26:26.690 --> 00:26:28.330
coming out from the nuclear fusion in the

687
00:26:28.330 --> 00:26:31.250
middle balances gravity pulling in. The

688
00:26:31.250 --> 00:26:33.730
more massive you are, the hotter and denser

689
00:26:33.730 --> 00:26:35.490
you get in the middle, so the more energy you

690
00:26:35.490 --> 00:26:38.250
give off. And the result of that is that it

691
00:26:38.650 --> 00:26:40.809
roughly, it varies a little bit by star's

692
00:26:40.809 --> 00:26:42.850
mass, but roughly the brightness of a star,

693
00:26:42.850 --> 00:26:45.570
the luminosity of a star is proportional to

694
00:26:45.570 --> 00:26:47.050
the mass of the star to the power

695
00:26:47.050 --> 00:26:49.890
4.3.54. Which means if you

696
00:26:49.890 --> 00:26:52.480
double the mass of a star, it'll get between

697
00:26:52.480 --> 00:26:54.560
10 and 16 times brighter.

698
00:26:55.440 --> 00:26:58.240
So twice the mass, Call it a factor of 10

699
00:26:58.240 --> 00:26:59.960
just to keep it easy. If it's 10 times

700
00:26:59.960 --> 00:27:02.600
brighter, that means it's burning its fuel 10

701
00:27:02.600 --> 00:27:04.880
times quicker to produce 10 times as much

702
00:27:04.880 --> 00:27:07.120
energy. But it's only twice the mass, so it's

703
00:27:07.120 --> 00:27:09.920
only got twice as much fuel, so its

704
00:27:09.920 --> 00:27:11.920
life will be a factor of five times shorter.

705
00:27:12.080 --> 00:27:13.800
And the more massive you get, the shorter the

706
00:27:13.800 --> 00:27:16.640
life gets. Now, stars of different masses

707
00:27:16.720 --> 00:27:19.330
have different. A star like Proxima

708
00:27:19.330 --> 00:27:21.770
Centauri will never swell up to become a red

709
00:27:21.770 --> 00:27:23.490
giant. It'll just be a dull, glowing ember

710
00:27:23.490 --> 00:27:26.090
and eventually go out. But even the

711
00:27:26.090 --> 00:27:28.570
oldest stars like Proxima Centauri are still

712
00:27:28.730 --> 00:27:30.370
really in their youth because they're burning

713
00:27:30.370 --> 00:27:33.170
their fuel so slowly. Stars that are more

714
00:27:33.170 --> 00:27:35.050
massive eventually get stars like the sun,

715
00:27:35.050 --> 00:27:37.520
which are what form like dwarfs. And, they

716
00:27:37.680 --> 00:27:39.600
eventually swell up to become a red giant,

717
00:27:39.600 --> 00:27:41.680
puff off their outer layers. And for a star

718
00:27:42.000 --> 00:27:44.930
of the Sun's mass, that process from

719
00:27:44.930 --> 00:27:46.770
forming to the end of its life is thought to

720
00:27:46.770 --> 00:27:49.010
be about 12 billion years. It used to be 10

721
00:27:49.010 --> 00:27:51.130
billion models seem to have refined. So

722
00:27:51.130 --> 00:27:52.730
people nowadays seem to say it's about 12

723
00:27:52.730 --> 00:27:55.690
billion years. So a star of

724
00:27:55.690 --> 00:27:58.180
the mass of the sun that formed when our,

725
00:27:58.180 --> 00:28:00.740
Milky Way was very young will have lived and

726
00:28:00.740 --> 00:28:02.900
died and become a white dwarf more than a

727
00:28:02.900 --> 00:28:05.860
billion years ago. But stars more massive

728
00:28:05.860 --> 00:28:08.180
than the sun can form white dwarfs as well,

729
00:28:08.180 --> 00:28:10.750
up to maybe two or even three times the mass

730
00:28:10.750 --> 00:28:12.590
of the sun, depending how effective it is at

731
00:28:12.590 --> 00:28:14.870
shedding mass at the end. Yeah, the maximum

732
00:28:14.870 --> 00:28:17.070
mass for white dwarf, you can get about 1.4

733
00:28:17.070 --> 00:28:19.390
times the mass of the Sun. If stars lose half

734
00:28:19.390 --> 00:28:20.750
their mass, that gives you something about

735
00:28:20.750 --> 00:28:22.710
three times the mass of the sun before you

736
00:28:22.710 --> 00:28:25.430
start it. Three times the mass of the sun.

737
00:28:26.150 --> 00:28:28.230
Three to the power four is three times three

738
00:28:28.230 --> 00:28:30.430
times three times three. That's 81 if my

739
00:28:30.430 --> 00:28:33.030
mental arithmetic is correct. So three times

740
00:28:33.030 --> 00:28:35.270
the mass of the sun burns its fuel 81 times

741
00:28:35.270 --> 00:28:38.050
as quickly, which means it would live a 27th

742
00:28:38.050 --> 00:28:40.930
as long. Which means instead of 12 billion

743
00:28:40.930 --> 00:28:43.400
years, you get down to, 1.2 billion years,

744
00:28:43.400 --> 00:28:45.360
you get down to or like, 600 million years,

745
00:28:45.440 --> 00:28:48.200
500 million years. So there will have been a

746
00:28:48.200 --> 00:28:50.520
lot of stars that were more m massive than

747
00:28:50.520 --> 00:28:52.560
the sun that have lived and died and created

748
00:28:52.560 --> 00:28:54.960
white dwarfs. And so there's going to be a

749
00:28:54.960 --> 00:28:57.880
lot of white dwarfs out there. I saw

750
00:28:57.880 --> 00:29:00.120
someone talking a while back about how old

751
00:29:00.120 --> 00:29:02.760
the oldest white dwarf will be in how dim it

752
00:29:02.760 --> 00:29:04.680
will be, because white dwarfs just cool and

753
00:29:04.680 --> 00:29:07.240
gradually go from being blue to white to

754
00:29:07.240 --> 00:29:09.360
yellow to red. You know, gradually dim down.

755
00:29:09.680 --> 00:29:11.910
Yeah. but what that all means is that there

756
00:29:11.910 --> 00:29:14.350
are probably a really large population of

757
00:29:14.350 --> 00:29:16.190
white dwarfs out there. We know quite a large

758
00:29:16.190 --> 00:29:19.030
number, but we won't know anywhere near

759
00:29:19.030 --> 00:29:21.230
as many of them as we do stars that are

760
00:29:21.230 --> 00:29:22.630
actually the mass of the sun, that are in the

761
00:29:22.630 --> 00:29:24.990
prime of their life because they're much

762
00:29:24.990 --> 00:29:27.110
fainter and harder to spot because they've

763
00:29:27.110 --> 00:29:28.670
got a much smaller surface area. So even

764
00:29:28.670 --> 00:29:30.130
though they're hot, they're tiny and,

765
00:29:30.080 --> 00:29:31.940
therefore they're faint. and the best example

766
00:29:31.940 --> 00:29:33.860
of that, of course, is a white dwarf that is

767
00:29:33.860 --> 00:29:36.220
a companion to Sirius. Sirius is the

768
00:29:36.220 --> 00:29:38.020
brightest star in the night sky. It's more

769
00:29:38.020 --> 00:29:40.860
massive than the Sun. It's also nearby. Its

770
00:29:41.100 --> 00:29:44.060
white dwarf companion is something

771
00:29:44.060 --> 00:29:46.940
like a factor of a million times fainter than

772
00:29:46.940 --> 00:29:49.500
Sirius is. So even though the white dwarf is

773
00:29:49.500 --> 00:29:51.660
comparable in Master Sirius A,

774
00:29:52.300 --> 00:29:55.060
it is like a million times dimmer because

775
00:29:55.060 --> 00:29:57.220
it's so tiny. And that's why they're Hard to

776
00:29:57.220 --> 00:29:57.500
find.

777
00:29:58.270 --> 00:30:00.070
Andrew Dunkley: Yeah, even though there's probably a hell of

778
00:30:00.070 --> 00:30:02.980
a lot of them out there. Okay, if you would

779
00:30:02.980 --> 00:30:05.180
like to read more about this particular white

780
00:30:05.180 --> 00:30:08.050
dwarf star that is, you know, got a case of

781
00:30:08.050 --> 00:30:10.610
the munchies, probably spent too much time

782
00:30:10.770 --> 00:30:13.360
smoking the juju. you can read all about it

783
00:30:14.240 --> 00:30:17.200
in the Astronomical Journal. This is Space

784
00:30:17.200 --> 00:30:20.080
Nuts with Andrew Dunkley and Jonti Horner.

785
00:30:20.240 --> 00:30:22.680
Jonti Horner: Okay, we checked all four systems and being

786
00:30:22.680 --> 00:30:24.170
with the jerk space nets,

787
00:30:25.140 --> 00:30:26.600
Andrew Dunkley: Don'T know why we went down that road.

788
00:30:26.600 --> 00:30:29.280
Let's go to our next story. And this

789
00:30:29.280 --> 00:30:32.050
one is, this one's close to home.

790
00:30:32.080 --> 00:30:35.030
a, an object that is rapidly developing

791
00:30:35.030 --> 00:30:37.840
a ring system and it's it's in

792
00:30:37.840 --> 00:30:40.080
the outer solar system.

793
00:30:40.480 --> 00:30:43.120
Jonti Horner: It is, this is an object called Chiron,

794
00:30:43.920 --> 00:30:45.920
which was the first of the centaurs to be

795
00:30:45.920 --> 00:30:47.240
discovered. And I always like to talk about

796
00:30:47.240 --> 00:30:48.920
the centaurs because they're what I studied

797
00:30:48.920 --> 00:30:51.660
for my PhD, so, so I was at one

798
00:30:51.660 --> 00:30:54.220
point, 20 odd years ago, one of the world's

799
00:30:54.220 --> 00:30:56.140
experts in how these things move around the

800
00:30:56.140 --> 00:30:57.740
solar system. And then science has moved on

801
00:30:57.740 --> 00:31:00.060
and I haven't, so I probably can no longer

802
00:31:00.060 --> 00:31:02.740
claim that. But Chiron is

803
00:31:02.820 --> 00:31:04.980
an interesting object. It's an icy object,

804
00:31:05.220 --> 00:31:08.220
bit more than 200km across. It was

805
00:31:08.220 --> 00:31:10.900
one of, if not the first object to get both a

806
00:31:10.900 --> 00:31:12.980
classification as an asteroid and as a comet.

807
00:31:13.540 --> 00:31:15.940
So it was initially discovered as a tiny

808
00:31:15.940 --> 00:31:17.460
speck of light moving around. It's discovered

809
00:31:17.460 --> 00:31:19.300
by Cowell I think in 1970,

810
00:31:20.340 --> 00:31:22.380
moving on an orbit that spends nearly all its

811
00:31:22.380 --> 00:31:24.220
time between the orbits of Saturn and Uranus.

812
00:31:24.220 --> 00:31:25.980
At the minute. Long term it's an unstable

813
00:31:25.980 --> 00:31:28.500
orbit. There's about a, ah, one in three

814
00:31:28.500 --> 00:31:29.940
chance that this will eventually end up in

815
00:31:29.940 --> 00:31:31.540
the inner solar system at some point in the

816
00:31:31.540 --> 00:31:33.780
next few million years. And that's part of

817
00:31:33.780 --> 00:31:36.060
the work I did during my PhD was running

818
00:31:36.060 --> 00:31:37.540
simulations of where this thing's going to

819
00:31:37.540 --> 00:31:40.100
go. That in itself is interesting because

820
00:31:40.100 --> 00:31:42.580
it's about a bit more than 200km across.

821
00:31:43.300 --> 00:31:44.900
So if this thing got trapped in the inner

822
00:31:44.900 --> 00:31:46.540
solar system, it will be, be a comet like

823
00:31:46.540 --> 00:31:48.780
nothing we've seen in recorded history. Hale

824
00:31:48.780 --> 00:31:51.660
Bopp, which was ridiculous, had a 50

825
00:31:51.660 --> 00:31:54.660
kilometer nucleus. If this thing's 250

826
00:31:54.660 --> 00:31:56.420
kilometers across, that's five times the

827
00:31:56.420 --> 00:31:59.220
radius, which means it's something like 25

828
00:31:59.220 --> 00:32:01.899
times the surface area, which means it will

829
00:32:01.899 --> 00:32:04.450
be a lot more impressive. So it's obviously

830
00:32:04.450 --> 00:32:07.130
an interesting object. Back in

831
00:32:07.130 --> 00:32:10.010
2011, team of scientists

832
00:32:10.410 --> 00:32:13.200
traveled across the world to gather to

833
00:32:13.200 --> 00:32:15.560
watch Chiron block out the light from a

834
00:32:15.640 --> 00:32:18.000
background star. So as this thing's moving

835
00:32:18.000 --> 00:32:20.560
through space, it just happened to pass in

836
00:32:20.560 --> 00:32:23.080
front of a star, from a subset of locations

837
00:32:23.080 --> 00:32:25.680
across the Earth. Now the distant stars are

838
00:32:25.680 --> 00:32:27.839
effectively so far away, we can consider the

839
00:32:27.839 --> 00:32:30.640
light coming in perfectly parallel. And

840
00:32:30.640 --> 00:32:32.200
so a 200 kilometer

841
00:32:33.000 --> 00:32:35.240
centaur will cast a shadow on the earth

842
00:32:35.240 --> 00:32:37.280
that's 200 kilometers across. And that shadow

843
00:32:37.280 --> 00:32:39.730
will whip across our planet. As the object

844
00:32:39.730 --> 00:32:41.570
and the Earth move around the sun, the shadow

845
00:32:41.570 --> 00:32:43.850
moves, the Earth moves through it. And so you

846
00:32:43.850 --> 00:32:46.850
get a 200 kilometer roughly scale band on the

847
00:32:46.850 --> 00:32:48.970
Earth where that star will disappear, then

848
00:32:48.970 --> 00:32:51.810
reappear. We know how fast everything's

849
00:32:51.810 --> 00:32:53.690
moving. So if you can get in that location,

850
00:32:54.010 --> 00:32:56.210
have a lot of telescopes spread out in a

851
00:32:56.210 --> 00:32:58.730
line, you can observe that

852
00:32:58.730 --> 00:33:01.330
occultation event and, by how long the star

853
00:33:01.330 --> 00:33:03.250
vanishes from different locations, you can

854
00:33:03.250 --> 00:33:05.640
actually figure out the shape and the size of

855
00:33:05.640 --> 00:33:08.320
the centaur because you can essentially map

856
00:33:08.560 --> 00:33:11.320
that shadow. And if you're near the edge, the

857
00:33:11.320 --> 00:33:12.880
star will disappear and reappear really

858
00:33:12.880 --> 00:33:14.520
quickly. If you're near the middle, you'll

859
00:33:14.520 --> 00:33:17.080
get a longer period where it vanishes. So

860
00:33:17.080 --> 00:33:18.720
these kind of, ah, occultation observations

861
00:33:18.800 --> 00:33:21.520
are really valuable to scientists. What

862
00:33:21.520 --> 00:33:23.560
happened in 2011 was they set their

863
00:33:23.560 --> 00:33:25.280
telescopes up and started watching a bit

864
00:33:25.280 --> 00:33:26.760
early to make sure they were looking at the

865
00:33:26.760 --> 00:33:29.320
star. And they noticed the star flickered on

866
00:33:29.320 --> 00:33:31.400
and off a couple of times before it properly

867
00:33:31.400 --> 00:33:33.540
disappeared for the main occultation. Then

868
00:33:33.540 --> 00:33:35.380
after it reappeared, it flickered on and off

869
00:33:35.380 --> 00:33:37.580
again a couple of times. And that's really

870
00:33:37.580 --> 00:33:40.420
weird. Now there was a kind of

871
00:33:40.420 --> 00:33:42.260
precedent for this with observations that

872
00:33:42.260 --> 00:33:44.780
were made in 1977, I believe,

873
00:33:45.100 --> 00:33:47.820
of Uranus, which was being observed from, I

874
00:33:47.820 --> 00:33:49.540
think it was the Kuiper Airborne Observatory

875
00:33:49.540 --> 00:33:52.100
doing one of these occultations. And they'd

876
00:33:52.100 --> 00:33:54.660
observed Uranus for this occultation because

877
00:33:54.660 --> 00:33:57.180
they wanted to understand the atmosphere of

878
00:33:57.180 --> 00:33:59.500
Uranus. And they figured as a stalwart behind

879
00:33:59.500 --> 00:34:02.109
Uranus, you'd see it not just disappear, but

880
00:34:02.109 --> 00:34:03.989
actually fade out as the light passed through

881
00:34:03.989 --> 00:34:06.149
the atmosphere. So you could measure the

882
00:34:06.149 --> 00:34:08.549
atmosphere and with that occultation of

883
00:34:08.549 --> 00:34:11.549
Uranus, occultation by Uranus, sorry, they

884
00:34:11.549 --> 00:34:12.949
got this flickering on and off thing. And

885
00:34:12.949 --> 00:34:14.749
that was the discovery of Uranus, of ring

886
00:34:14.749 --> 00:34:17.749
system. So basically the star vanished behind

887
00:34:17.749 --> 00:34:19.149
the rings, then reappeared, then vanished

888
00:34:19.149 --> 00:34:20.749
again, then reappeared, then went behind the

889
00:34:20.749 --> 00:34:23.629
planet. Right. So with this

890
00:34:23.629 --> 00:34:26.589
2011 event, the same kind of thing applied.

891
00:34:27.179 --> 00:34:29.139
It was the discovery of a ring system around

892
00:34:29.139 --> 00:34:31.259
this icy object. So this is a tiny thing,

893
00:34:31.899 --> 00:34:34.539
smaller than even Mimas, that we talked about

894
00:34:34.539 --> 00:34:36.299
last week with the subsurface ocean,

895
00:34:36.539 --> 00:34:38.419
something so small that its gravity is

896
00:34:38.419 --> 00:34:39.659
probably not strong enough to make it

897
00:34:39.659 --> 00:34:42.360
spherical. It's probably peanut shaped or

898
00:34:42.349 --> 00:34:44.028
rugby ball shaped or something like this.

899
00:34:44.028 --> 00:34:46.508
It's probably not spherical. Around this

900
00:34:46.508 --> 00:34:48.628
object, it seems that there is a system of

901
00:34:48.628 --> 00:34:50.268
rings where there are three or four narrow

902
00:34:50.268 --> 00:34:52.548
rings at various distances. I think the

903
00:34:52.548 --> 00:34:55.419
distances are something like 273, 325, 438

904
00:34:55.419 --> 00:34:58.379
and 1400 kilometers from the

905
00:34:58.379 --> 00:35:01.259
center of Chiron. Got this ring

906
00:35:01.259 --> 00:35:03.819
system and it's been observed again since

907
00:35:03.819 --> 00:35:06.739
they did observations in 2018, 2022 and

908
00:35:06.739 --> 00:35:09.579
2023, where they again figured

909
00:35:09.579 --> 00:35:11.579
out that the shadow of Chiron was going to

910
00:35:11.579 --> 00:35:13.939
scan across the planet, got a load of

911
00:35:13.939 --> 00:35:16.299
telescopes, went on a road trip and observed

912
00:35:16.299 --> 00:35:18.739
it happen to get more information about the

913
00:35:18.739 --> 00:35:21.059
rings. Because having a ring system around an

914
00:35:21.059 --> 00:35:23.139
object that isn't a planet is really cool.

915
00:35:23.649 --> 00:35:23.969
Andrew Dunkley: Yeah.

916
00:35:24.049 --> 00:35:26.489
Jonti Horner: And how did it form? How long has it been

917
00:35:26.489 --> 00:35:28.329
there? What's going on? How common are ring

918
00:35:28.329 --> 00:35:31.249
systems like this? Incidentally, a former PhD

919
00:35:31.249 --> 00:35:33.649
student of mine, Jeremy Wood, did some really

920
00:35:33.649 --> 00:35:36.089
cool dynamical studies that basically showed

921
00:35:36.089 --> 00:35:38.289
that the ring system could be

922
00:35:38.449 --> 00:35:40.809
primordial. It could be as old as the solar

923
00:35:40.809 --> 00:35:43.129
system. From the point of view of Chiron has

924
00:35:43.129 --> 00:35:45.009
never been close enough to one of the planets

925
00:35:45.009 --> 00:35:48.009
to disrupt the rings. So that

926
00:35:48.009 --> 00:35:49.529
doesn't put an edge limit on it, but it was

927
00:35:49.529 --> 00:35:52.169
still quite cool. What the new observations

928
00:35:52.169 --> 00:35:53.749
have shown though, is that, the ring system

929
00:35:53.829 --> 00:35:56.309
now seems to be different to how it was in

930
00:35:56.309 --> 00:35:59.269
2011. In other words, the ring

931
00:35:59.269 --> 00:36:01.949
system is evolving before our very

932
00:36:01.949 --> 00:36:04.069
eyes and it actually seems to be a denser,

933
00:36:04.069 --> 00:36:06.829
stronger ring system now than it was 10 or 15

934
00:36:06.829 --> 00:36:09.109
years ago. So it's possible that we're

935
00:36:09.109 --> 00:36:11.389
actually witnessing this ring system as it is

936
00:36:11.389 --> 00:36:14.069
forming or as it's changing over time.

937
00:36:14.069 --> 00:36:16.869
Now I know Chiron has been quite active,

938
00:36:17.309 --> 00:36:19.469
it's been outgassing because it's been closer

939
00:36:19.469 --> 00:36:21.629
to the sun, hence the cometary type

940
00:36:21.629 --> 00:36:24.629
classification it got. Maybe some

941
00:36:24.629 --> 00:36:26.309
of the material it's ejecting in that

942
00:36:26.309 --> 00:36:28.389
outgassing is being ejected gently enough

943
00:36:28.389 --> 00:36:31.009
that it doesn't escape from Chiron and,

944
00:36:30.959 --> 00:36:33.799
that's repopulating the rings. We just don't

945
00:36:33.799 --> 00:36:36.719
know. But the only way we'll find

946
00:36:36.719 --> 00:36:38.399
out is by doing more of these observations.

947
00:36:38.399 --> 00:36:41.279
But I think it's just really exciting and

948
00:36:41.279 --> 00:36:44.229
it's a really good reminder again that we

949
00:36:44.229 --> 00:36:46.069
always kind of imagine the solar system as a

950
00:36:46.069 --> 00:36:48.429
very sad and boring, placid place where not

951
00:36:48.429 --> 00:36:50.709
much changing anymore because it's four and a

952
00:36:50.709 --> 00:36:52.389
half billion years old. And as you get older,

953
00:36:52.389 --> 00:36:53.949
you Get a bit more sedentary and not much

954
00:36:53.949 --> 00:36:56.829
happens. But in fact it's a reminder that

955
00:36:56.829 --> 00:36:59.269
the solar system's a really dynamic place and

956
00:36:59.349 --> 00:37:01.269
things are constantly influenced, constantly

957
00:37:01.269 --> 00:37:03.429
changing. We talked about it last week. The

958
00:37:03.429 --> 00:37:05.829
ocean on Mimas that is possibly

959
00:37:06.149 --> 00:37:08.469
only 15 million years old. Now, 50 million

960
00:37:08.469 --> 00:37:11.029
years sounds like a really long time, but in

961
00:37:11.029 --> 00:37:12.749
a system that's four and a half thousand

962
00:37:12.749 --> 00:37:15.709
million years old, that's like something

963
00:37:15.709 --> 00:37:17.829
that has happened to me in the last couple of

964
00:37:17.829 --> 00:37:20.389
weeks. That's a new feature, not something

965
00:37:20.389 --> 00:37:22.389
I've had since birth. And this is yet another

966
00:37:22.389 --> 00:37:24.069
example of the fact that the solar system

967
00:37:24.069 --> 00:37:26.709
just seems to be continually rapidly changing

968
00:37:26.709 --> 00:37:27.309
and evolving.

969
00:37:27.789 --> 00:37:29.629
Andrew Dunkley: Yeah, yeah, it's a really interesting

970
00:37:29.789 --> 00:37:32.769
situation. how far out is chiron?

971
00:37:33.809 --> 00:37:36.089
Jonti Horner: It varies. So it's closest to the sun, It's a

972
00:37:36.089 --> 00:37:37.729
little bit closer to the sun than the orbit

973
00:37:37.729 --> 00:37:39.719
of Saturn. at its furthest, it's a bit

974
00:37:39.719 --> 00:37:41.279
further away than the orbit of Uranus. And

975
00:37:41.279 --> 00:37:42.959
that's an unstable orbit. So it bounces

976
00:37:42.959 --> 00:37:45.479
around over time, it will have encounters

977
00:37:45.479 --> 00:37:47.839
with them that fling it around. But at the

978
00:37:47.839 --> 00:37:50.399
minute it's in the outer solar system

979
00:37:50.479 --> 00:37:53.159
between the orbits of Saturn and Uranus most

980
00:37:53.159 --> 00:37:55.679
of the time. Unstable solution. It probably

981
00:37:55.679 --> 00:37:57.719
originated out beyond the orbit of Neptune.

982
00:37:57.719 --> 00:38:00.199
And it's one of this population called the

983
00:38:00.199 --> 00:38:03.059
Centaurs that are, the future parents of the

984
00:38:03.059 --> 00:38:04.699
next generation of short period comets.

985
00:38:04.699 --> 00:38:06.139
Effectively in the same way that the near

986
00:38:06.139 --> 00:38:08.379
Earth asteroids have their origin in the

987
00:38:08.379 --> 00:38:10.939
asteroid belt, short period comets have their

988
00:38:10.939 --> 00:38:13.579
origin in the Transeptunian region. But to

989
00:38:13.579 --> 00:38:15.059
get here from there, they've got to pass

990
00:38:15.059 --> 00:38:16.419
through the outer solar system. And that's

991
00:38:16.419 --> 00:38:17.459
what the Centaurs are.

992
00:38:18.019 --> 00:38:20.299
Andrew Dunkley: Okay. Fascinating. Yeah, it's really

993
00:38:20.299 --> 00:38:22.659
interesting and probably not one that,

994
00:38:23.048 --> 00:38:25.529
too many people would be aware of. I remember

995
00:38:25.529 --> 00:38:28.529
when it was making the news some

996
00:38:28.529 --> 00:38:30.969
years ago, and that's why the name stuck when

997
00:38:30.969 --> 00:38:33.499
you, when you sent the story to me. But, you

998
00:38:33.499 --> 00:38:35.459
don't really hear much about it. But now

999
00:38:35.929 --> 00:38:37.769
we've got a very good reason to look at it.

1000
00:38:38.209 --> 00:38:40.129
if you would like to look into that

1001
00:38:40.129 --> 00:38:43.009
particular paper, it's been published in

1002
00:38:43.009 --> 00:38:45.809
the Astrophysical Journal Letters.

1003
00:38:51.809 --> 00:38:53.729
Our final story, Jonti, is,

1004
00:38:54.689 --> 00:38:57.449
an exoplanet that the popular press are going

1005
00:38:57.449 --> 00:38:59.909
to say has got, some kind of life on it. it's

1006
00:38:59.909 --> 00:39:02.759
a, it's a maybe life candidate, story,

1007
00:39:02.759 --> 00:39:05.749
this one. And Yeah, but they're still

1008
00:39:05.749 --> 00:39:07.309
using the term super Earth.

1009
00:39:07.469 --> 00:39:09.869
Jonti Horner: Yeah, I'll keep this one a little bit short

1010
00:39:09.869 --> 00:39:12.709
and try not to get too grumpy. But one of my

1011
00:39:12.709 --> 00:39:15.549
big bug bears all the way through my career

1012
00:39:15.629 --> 00:39:18.479
is a good way for people to get media

1013
00:39:18.479 --> 00:39:20.679
coverage of their new planet discovery is say

1014
00:39:20.679 --> 00:39:23.119
it could be habitable. It's in the Goldilocks

1015
00:39:23.119 --> 00:39:23.759
zone. Hooray.

1016
00:39:24.079 --> 00:39:25.279
Andrew Dunkley: Using the L word.

1017
00:39:25.599 --> 00:39:27.119
Jonti Horner: Rumble, rumble, grumble, grumble.

1018
00:39:27.199 --> 00:39:28.879
Andrew Dunkley: It's a four letter word too, that one.

1019
00:39:28.879 --> 00:39:30.829
Jonti Horner: It is, and it's one of the terrible four

1020
00:39:30.829 --> 00:39:33.669
letter words. Part of the problem here is

1021
00:39:33.659 --> 00:39:35.499
there's this concept of the Goldilocks zone,

1022
00:39:35.499 --> 00:39:37.019
of the habitable zone, which has become

1023
00:39:37.019 --> 00:39:38.939
really entrenched in the popular

1024
00:39:38.939 --> 00:39:41.139
consciousness. And it's always viewed as

1025
00:39:41.139 --> 00:39:43.539
being this sweet spot for life. And the idea

1026
00:39:43.539 --> 00:39:45.219
is that if you have a planet in the habitable

1027
00:39:45.219 --> 00:39:46.659
zone, it will have liquid water on its

1028
00:39:46.659 --> 00:39:48.739
surface and all sorts of happy life things

1029
00:39:48.739 --> 00:39:51.179
will happen and everything will be good.

1030
00:39:52.169 --> 00:39:54.649
What it actually means is that if you took

1031
00:39:54.649 --> 00:39:56.829
the Earth, as it is today and put it where

1032
00:39:56.829 --> 00:39:59.149
that planet is, the Earth would still

1033
00:39:59.149 --> 00:40:01.869
maintain its liquid water because planets are

1034
00:40:01.869 --> 00:40:04.669
really diverse. If you took Venus and put

1035
00:40:04.669 --> 00:40:06.349
Venus where the Earth is, With Venus's

1036
00:40:06.349 --> 00:40:08.109
current atmosphere, Venus will be too hot to

1037
00:40:08.109 --> 00:40:10.469
have liquid water. But if you observe the

1038
00:40:10.469 --> 00:40:12.589
solar system from a long long way away and

1039
00:40:12.589 --> 00:40:15.079
you discovered Venus on the Earth's

1040
00:40:15.079 --> 00:40:17.729
orbit, it wouldn't look any different to the

1041
00:40:17.729 --> 00:40:19.059
Earth. it's a planet about the size of the

1042
00:40:19.059 --> 00:40:21.069
Earth, sat in the habitable sun. We, it's

1043
00:40:21.069 --> 00:40:23.709
habitable. Hooray. Whereas Venus is actually

1044
00:40:23.709 --> 00:40:25.749
so hot that on the surface it had melt lead.

1045
00:40:25.749 --> 00:40:27.629
And I certainly wouldn't want to visit there.

1046
00:40:27.629 --> 00:40:30.389
It's even hotter than my room was the other

1047
00:40:30.389 --> 00:40:32.869
night when the power cut had happened. And

1048
00:40:32.869 --> 00:40:35.849
that was bad enough and brutal enough. so

1049
00:40:35.849 --> 00:40:38.329
what this means is that ah, people

1050
00:40:38.649 --> 00:40:40.729
have become very fond of

1051
00:40:41.809 --> 00:40:44.609
find a planet around a star, you can work out

1052
00:40:44.849 --> 00:40:46.649
where the boundaries of the habitable zone

1053
00:40:46.649 --> 00:40:48.649
will be based on a few assumptions. And this

1054
00:40:48.649 --> 00:40:51.409
is work going back about a decade of the

1055
00:40:51.409 --> 00:40:53.129
definitions we use now. And you've got the

1056
00:40:53.129 --> 00:40:55.249
conservative and the optimistic habitable

1057
00:40:55.249 --> 00:40:57.399
zone, which are basically loosely based

1058
00:40:57.399 --> 00:40:59.839
around the fact that if you're as close to

1059
00:40:59.839 --> 00:41:02.279
the star that you get an amount of radiation

1060
00:41:02.279 --> 00:41:04.119
coming in comparable to Venus, you'll be too

1061
00:41:04.119 --> 00:41:05.959
hot. If you're about where Mars is, you'll be

1062
00:41:05.959 --> 00:41:07.359
too cold, but in the middle you'll be just

1063
00:41:07.359 --> 00:41:09.899
right m. and that's about it.

1064
00:41:10.059 --> 00:41:12.659
Now that definition doesn't really take any

1065
00:41:12.659 --> 00:41:14.339
account of the mass of the planet or its

1066
00:41:14.339 --> 00:41:17.339
atmosphere. What that

1067
00:41:17.339 --> 00:41:20.099
means is that ah, when you find a planet that

1068
00:41:20.099 --> 00:41:22.139
is a super Earth that Is four times the mass

1069
00:41:22.139 --> 00:41:24.539
of the Earth. That is almost certainly

1070
00:41:24.859 --> 00:41:27.019
nothing like our planet at all.

1071
00:41:27.899 --> 00:41:30.059
You'll do a calculation and say it sits in

1072
00:41:30.059 --> 00:41:32.779
the optimistic habitable zone. So there is a

1073
00:41:32.779 --> 00:41:34.419
potential it could have liquid water on its

1074
00:41:34.419 --> 00:41:37.369
surface. That's full of a whole heap

1075
00:41:37.369 --> 00:41:39.409
of assumptions. But to me it's a really long

1076
00:41:39.409 --> 00:41:41.009
stretch from saying it could have life.

1077
00:41:41.649 --> 00:41:41.969
Andrew Dunkley: A.

1078
00:41:41.969 --> 00:41:43.409
Jonti Horner: You're assuming it's got the right kind of

1079
00:41:43.409 --> 00:41:45.529
atmosphere to have liquid water where it's

1080
00:41:45.529 --> 00:41:46.889
four times the mass of the Earth. So its

1081
00:41:46.889 --> 00:41:48.589
atmosphere is almost certainly much, much m

1082
00:41:48.609 --> 00:41:50.689
thicker, Therefore

1083
00:41:51.329 --> 00:41:53.649
likely has a much stronger greenhouse effect,

1084
00:41:54.049 --> 00:41:55.969
Therefore probably runaway greenhouse. Not

1085
00:41:55.969 --> 00:41:56.289
good.

1086
00:41:56.849 --> 00:41:58.729
The other thing with this particular planet,

1087
00:41:58.729 --> 00:42:01.499
GJ 251C is it's a super

1088
00:42:01.499 --> 00:42:03.639
Earth orbiting a red dwarf star, ah,

1089
00:42:04.259 --> 00:42:06.749
nearby, less than 20 light years away. And

1090
00:42:06.749 --> 00:42:08.389
that's part of why people are excited. It's

1091
00:42:08.389 --> 00:42:09.869
near enough that we'll learn a lot more about

1092
00:42:09.869 --> 00:42:11.909
it in the future. However,

1093
00:42:12.629 --> 00:42:15.069
planet orbiting a red dwarf star means that

1094
00:42:15.069 --> 00:42:16.609
to be in the habitable zone, it's got to be

1095
00:42:16.609 --> 00:42:18.889
close in. This thing goes around its star

1096
00:42:18.889 --> 00:42:21.689
every 54 days, which means that it is

1097
00:42:21.689 --> 00:42:23.729
closer to its star than Mercury is to the

1098
00:42:23.729 --> 00:42:25.769
sun. And given the difference in the masses,

1099
00:42:25.769 --> 00:42:28.239
it's actually much closer in than that. That

1100
00:42:28.239 --> 00:42:30.439
means it's up close and personal with a red

1101
00:42:30.439 --> 00:42:32.759
dwarf star, which are notorious for being

1102
00:42:32.999 --> 00:42:35.479
active and flary and noisy, Particularly when

1103
00:42:35.479 --> 00:42:37.279
they're young. They're tempestuous teenagers

1104
00:42:37.279 --> 00:42:40.239
in their early days with mega stellar flares

1105
00:42:40.239 --> 00:42:43.039
and stuff like this. So it seems to be

1106
00:42:43.039 --> 00:42:44.999
fairly widely accepted that planets around

1107
00:42:44.999 --> 00:42:47.679
red dwarf stars that are close enough to be

1108
00:42:47.679 --> 00:42:50.119
warm enough to have liquid water will have a

1109
00:42:50.119 --> 00:42:51.879
hard time holding onto their atmospheres,

1110
00:42:51.959 --> 00:42:53.119
Particularly when the stars are young,

1111
00:42:53.119 --> 00:42:55.769
because it'll be having all sorts of

1112
00:42:55.769 --> 00:42:57.819
bonkers fun. And that's kind of borne out

1113
00:42:57.899 --> 00:43:00.699
with the planets around Trappist 1, which for

1114
00:43:00.699 --> 00:43:02.939
years have been people saying these are the

1115
00:43:02.939 --> 00:43:04.499
most Earth like planets ever and we'll find

1116
00:43:04.499 --> 00:43:06.899
life on them and hooray. And then when they

1117
00:43:06.899 --> 00:43:08.539
finally got to use the James Webb space

1118
00:43:08.539 --> 00:43:10.739
telescope and look at those planets, none of

1119
00:43:10.739 --> 00:43:13.179
them have an atmosphere. Now I don't know

1120
00:43:13.179 --> 00:43:15.499
about you, but I kind of like to breathe.

1121
00:43:15.659 --> 00:43:17.949
It's a fairly important part of living. And a

1122
00:43:17.949 --> 00:43:19.949
planet without an atmosphere is not going to

1123
00:43:19.949 --> 00:43:21.629
have liquid water on the surface because if

1124
00:43:21.629 --> 00:43:23.029
you take the atmosphere away, there's no

1125
00:43:23.029 --> 00:43:25.769
pressure, the oceans boil and then are blown

1126
00:43:25.769 --> 00:43:28.129
away by the red dwarfs, which makes that

1127
00:43:28.129 --> 00:43:30.249
planet a desiccated husk, which not

1128
00:43:30.249 --> 00:43:32.929
particularly habitable. The reason I Get

1129
00:43:33.169 --> 00:43:35.969
energized and activated about this. It's a

1130
00:43:35.969 --> 00:43:37.729
lovely discovery. It's a really interesting

1131
00:43:37.729 --> 00:43:39.439
planet. We'll, learn a lot more about planets

1132
00:43:39.439 --> 00:43:41.999
elsewhere. If there is an atmosphere, it's

1133
00:43:41.999 --> 00:43:43.639
around us now that's near enough to us that

1134
00:43:43.639 --> 00:43:45.119
with James Webb, we'll be able to study it,

1135
00:43:45.119 --> 00:43:46.599
learn more about the atmosphere. We'll learn

1136
00:43:46.599 --> 00:43:48.759
a whole heap from it. But I get really

1137
00:43:48.759 --> 00:43:50.479
energized about this because there's only so

1138
00:43:50.479 --> 00:43:52.399
many times that people can hear a story that

1139
00:43:52.399 --> 00:43:54.519
says we found the most Earth like planet ever

1140
00:43:55.239 --> 00:43:57.639
before they think we found the Earth before

1141
00:43:57.639 --> 00:44:00.279
they think we found life elsewhere. And that

1142
00:44:00.279 --> 00:44:02.359
then really devalues it. When we finally do

1143
00:44:02.359 --> 00:44:04.799
find planets that are, ah, properly like the

1144
00:44:04.799 --> 00:44:07.439
Earth, when we do find signs of life

1145
00:44:07.439 --> 00:44:09.759
elsewhere, scientists will be getting really

1146
00:44:09.759 --> 00:44:11.279
excited because we've finally done it. And

1147
00:44:11.279 --> 00:44:13.079
everybody will be like, well, why bother?

1148
00:44:13.079 --> 00:44:15.439
You've done this a million times before. The

1149
00:44:15.439 --> 00:44:16.999
whole boy who cried wolf thing

1150
00:44:18.519 --> 00:44:21.199
again, a big bugbear. And something that's

1151
00:44:21.199 --> 00:44:22.759
really critically important these days is

1152
00:44:22.759 --> 00:44:25.629
trust in science and trust in scientists. We,

1153
00:44:25.779 --> 00:44:27.819
we've got all the controversies about topics

1154
00:44:27.819 --> 00:44:29.249
that, are much more controversial than we're

1155
00:44:29.249 --> 00:44:31.369
talking about with astronomy, with vaccine

1156
00:44:31.369 --> 00:44:34.169
denial, with climate change denial, with

1157
00:44:34.169 --> 00:44:36.449
people refusing to evacuate in the path of a

1158
00:44:36.449 --> 00:44:38.409
hurricane that's coming because they don't

1159
00:44:38.409 --> 00:44:41.289
believe the scientists. Anything that

1160
00:44:41.528 --> 00:44:44.009
makes people less trusting of scientists

1161
00:44:44.009 --> 00:44:46.809
because they're overblowing stories is

1162
00:44:46.809 --> 00:44:49.809
damaging now far more than it has been in

1163
00:44:49.809 --> 00:44:51.569
decades past. It's part of why I get so

1164
00:44:51.569 --> 00:44:54.209
frustrated with Avi Loeb and Three Eye Atlas.

1165
00:44:54.209 --> 00:44:56.739
It's why get frustrated with the media

1166
00:44:56.739 --> 00:44:58.259
coverage of stories like this and the

1167
00:44:58.259 --> 00:45:00.819
scientists pushing, I think, somewhat

1168
00:45:00.819 --> 00:45:03.299
unethically an argument that this could be a

1169
00:45:03.299 --> 00:45:06.259
habitable planet because it makes

1170
00:45:06.259 --> 00:45:07.819
the rest of us look like fools. And it makes

1171
00:45:07.819 --> 00:45:10.259
people, it gives them ammunition to say,

1172
00:45:10.259 --> 00:45:12.819
well, scientists lie to us when they're not.

1173
00:45:13.379 --> 00:45:15.339
They're saying that this meets the criteria

1174
00:45:15.339 --> 00:45:16.819
for the Habitable Zone paper that was

1175
00:45:16.819 --> 00:45:19.219
published 10 years ago. But

1176
00:45:19.539 --> 00:45:21.899
it weakens that trust in science, which is so

1177
00:45:21.899 --> 00:45:23.739
important now more than it ever has done. And

1178
00:45:23.739 --> 00:45:25.369
I said I wouldn't go on a run and I'm now

1179
00:45:25.839 --> 00:45:27.719
waving the flag and banging the table and all

1180
00:45:27.719 --> 00:45:30.359
the rest of it. But it's a frustration that's

1181
00:45:30.359 --> 00:45:32.159
wider than this story. And this story is

1182
00:45:32.159 --> 00:45:34.799
lovely. It's an awesome discovery. They found

1183
00:45:34.799 --> 00:45:36.519
a planet going around a star. That's very

1184
00:45:36.519 --> 00:45:38.399
cool. We'll learn a lot more about it. It's a

1185
00:45:38.399 --> 00:45:41.159
brilliant result. You don't need to tag every

1186
00:45:41.159 --> 00:45:43.079
result like this and say that this planet

1187
00:45:43.079 --> 00:45:43.759
could have life.

1188
00:45:45.519 --> 00:45:47.759
Andrew Dunkley: And yet that's what, that's what happens.

1189
00:45:47.719 --> 00:45:49.419
it's sort of like, what artificial

1190
00:45:49.419 --> 00:45:51.619
intelligence is doing to social media. You

1191
00:45:51.619 --> 00:45:53.999
don't know. You don't know what you're

1192
00:45:53.999 --> 00:45:56.719
looking at anymore. And my

1193
00:45:56.719 --> 00:45:59.559
trust levels have dropped significantly in

1194
00:45:59.559 --> 00:46:00.199
recent months.

1195
00:46:02.119 --> 00:46:04.729
Jonti Horner: My dad is, 80, and

1196
00:46:04.729 --> 00:46:06.529
he's still on Facebook. And he doesn't like

1197
00:46:06.529 --> 00:46:08.329
it, but he's on it because it's a way to

1198
00:46:08.329 --> 00:46:10.089
communicate with people back in the uk. Moved

1199
00:46:10.089 --> 00:46:12.609
over here a few years ago and he's constantly

1200
00:46:12.609 --> 00:46:14.529
saying to me, he's getting so frustrated with

1201
00:46:14.529 --> 00:46:16.929
these AI stories and fake news things that he

1202
00:46:16.929 --> 00:46:18.569
doesn't know what to trust on there anymore

1203
00:46:18.649 --> 00:46:21.059
because he'll see a story that some famous

1204
00:46:21.059 --> 00:46:23.659
actors died and then he'll look up on

1205
00:46:23.659 --> 00:46:25.459
Wikipedia and they're still alive and kicking

1206
00:46:25.459 --> 00:46:26.779
and they've got a film coming out. But

1207
00:46:26.779 --> 00:46:28.099
there's this thing of, you'd never believe

1208
00:46:28.099 --> 00:46:31.059
the tragic photos. And it's

1209
00:46:31.059 --> 00:46:33.699
bizarre. And at a time when we need fidelity

1210
00:46:33.699 --> 00:46:36.019
and trust in our news and trust in our

1211
00:46:36.019 --> 00:46:38.979
science, we've got to be careful about how

1212
00:46:38.979 --> 00:46:41.099
much hyperbole we put into stories. I think.

1213
00:46:41.419 --> 00:46:43.979
Andrew Dunkley: I totally agree. Yes. If you'd like to read

1214
00:46:43.979 --> 00:46:46.809
about that, particular exoplanet, you can,

1215
00:46:47.159 --> 00:46:49.619
pick up that yarn through the Astronomical

1216
00:46:49.619 --> 00:46:51.419
Journal where they publish the paper. Or you

1217
00:46:51.419 --> 00:46:53.519
can read up on all the stories we've talked

1218
00:46:53.519 --> 00:46:53.719
about

1219
00:46:53.719 --> 00:46:56.639
today@space.com

1220
00:46:57.199 --> 00:46:59.569
and I'm sure a few other, platforms have

1221
00:46:59.569 --> 00:47:00.569
published them as well.

1222
00:47:01.019 --> 00:47:03.169
and that brings us to the end of, this

1223
00:47:03.409 --> 00:47:05.329
program. Jonti, thank you so much.

1224
00:47:05.969 --> 00:47:07.729
Jonti Horner: It's a pleasure. It's lovely to chat. Thanks

1225
00:47:07.729 --> 00:47:09.609
for bearing with me, being a bit flighty and

1226
00:47:09.609 --> 00:47:11.329
flirty thanks to the power cuts and the

1227
00:47:11.329 --> 00:47:11.649
weather.

1228
00:47:12.529 --> 00:47:15.129
Andrew Dunkley: You've done well. You've done well. We'll,

1229
00:47:15.129 --> 00:47:17.129
catch you on the next program, a Q and A

1230
00:47:17.129 --> 00:47:19.099
program. Johnty, Horn, a professor of

1231
00:47:19.099 --> 00:47:21.419
astrophysics at the University University of

1232
00:47:21.419 --> 00:47:24.079
Southern Queens. And thanks to Huw in the

1233
00:47:24.079 --> 00:47:26.399
studio, who couldn't be with us today

1234
00:47:27.119 --> 00:47:30.119
because he never tells me. I

1235
00:47:30.119 --> 00:47:32.639
have no idea. I just make up the reasons he's

1236
00:47:32.639 --> 00:47:34.839
not here. I honestly don't know why he didn't

1237
00:47:34.839 --> 00:47:36.719
turn up this week. Probably because we didn't

1238
00:47:36.719 --> 00:47:37.839
tell him when we were recording.

1239
00:47:38.319 --> 00:47:39.359
Jonti Horner: That might have been it.

1240
00:47:39.569 --> 00:47:41.769
Andrew Dunkley: and from me, Andrew Dunkley, thanks for your

1241
00:47:41.769 --> 00:47:44.409
company. Catch you on the very next episode

1242
00:47:44.409 --> 00:47:46.049
of Space Nuts. Bye.

1243
00:47:46.049 --> 00:47:46.369
Jonti Horner: Bye.

1244
00:47:47.409 --> 00:47:49.689
You've been listening to the Space Nuts

1245
00:47:49.689 --> 00:47:52.609
podcast, available at

1246
00:47:52.609 --> 00:47:54.569
Apple Podcasts, Spotify,

1247
00:47:54.729 --> 00:47:57.529
iHeartRadio or your favorite podcast

1248
00:47:57.529 --> 00:47:59.889
player. You can also stream on demand at

1249
00:47:59.889 --> 00:48:00.969
bytes. Com.

1250
00:48:01.289 --> 00:48:03.369
Andrew Dunkley: This has been another quality podcast

1251
00:48:03.369 --> 00:48:05.099
production from Bytes. Com.