White Dwarfs, Black Holes & Cosmic Oddities Unpacked | Q&A

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Andrew Dunkley: Hi there. Thanks for joining us on another

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episode of Space Nuts. This is a Q and A

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edition. This is where we answer audience

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questions. Well, we read them out or we

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listen to them and we nod

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and then we go home. Uh, today we're

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going to be discussing white dwarf stars. An

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interesting question, a double barreled

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question in fact. Um, we've got

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one about uh, the different size of black

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holes. Gosh, a question about black holes.

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How odd. Uh, the effect of being in orbit

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come up and Casey wants to know about

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some of the oddities that exist in the

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cosmos. We'll cover all of that in this

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edition of space nuts. 15

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seconds. Guidance is internal. 10,

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9, ignition sequence start.

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Professor Fred Watson: Space nuts.

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Andrew Dunkley: 5, 4, 3, 2. 1, 2, 3, 4,

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

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nuts. Astronauts report it feels good.

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And Fred Watson brought with him today his

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brain the size of a planet to answer all your

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questions. Professor Fred Watson, what's an

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astronomer at large? Hello Fred Watson.

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Professor Fred Watson: Hello Andrew. Fancy seeing you here.

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Andrew Dunkley: It's unusual, isn't it, really?

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We've got a fair bit to get through, so we

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might just get straight into it, uh,

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as they say in Britain, we'll muck in.

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Professor Fred Watson: Um, I think it's, you'll find it's muckin

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nookin mukin.

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Andrew Dunkley: I've got to get the accent right.

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Professor Fred Watson: Yes, of course.

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Andrew Dunkley: All right, uh, our first question comes from

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Bloomington, Indiana. Two questions, if I

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may, about white dwarf stars. After a very

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long period of initial cooling, white

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dwarf stars undergo crystallisation before

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eventually transforming into theoretical

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black dwarf objects. So the

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questions are, uh, what is the process of

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crystallisation and how might crystallisation

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slow the further cooling of a white dwarf for

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such an incredibly long time? Thank you very

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much for your terrific podcast, Keep Smiling

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in the Land down under. That comes from Mark.

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Thank you, Mark. Lovely to hear from you. We

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don't talk all that often about white dwarfs,

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although we have had them pop up a couple of

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times lately. But um, yeah, you might want to

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tackle that uh, process of crystallisation

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first. What is that?

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Professor Fred Watson: Uh, so, um, you need to sort of think about

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what a white dwarf is before you get to the

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crystallisation.

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Andrew Dunkley: I suppose so, yeah, yeah. Is that what our,

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uh, sun's going to turn into?

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Professor Fred Watson: Yeah, yeah it is. So, uh, a couple of weeks

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time, I think, uh, it was it

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uh, after tomorrow, wasn't it? I can't

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remember. Yeah, anyway, um, it's or the, the

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Andrew Dunkley: billionth of a year after tomorrow.

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Professor Fred Watson: Yes, it's about, uh, so

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it will be in the region of 5 billion

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years.

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Andrew Dunkley: Oh, that's okay.

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Professor Fred Watson: Then have to put up with that. So

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uh, as well, let's take this and as an

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example, so the um, the outer.

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So what, what basically happens at the

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moment? We've got this reaction taking place

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that converts hydrogen into helium

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and produces a few other things as well.

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There are other reactions going on, uh, many

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of which produce carbon. Uh, and so

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carbon sort of builds up in the core

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of the sun over

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time and in particular as, as it

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gets nearer the end of its life it becomes

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quite carbon rich, uh, the

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nuc. So um,

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when it sheds its outer

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atmosphere and turns into what we call a

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planetary nebula. Nothing to do with planets,

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it's just that the early astronomers thought

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they looked like planets, but they're

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actually clouds of gas. Yeah, um, William

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Herschel, who called them planetary nebulae,

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he called a lot of things their names that we

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still use. Very eminent astronomer.

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Anyway, you get a planetary nebula,

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uh, but the, the core of the

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star that's left

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uh, behind basically

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collapses under its own gravity because it

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doesn't have the radiation any longer to

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support a swollen star. If

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I can put it that way. Radiation's gone.

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So uh, it's still. But it's incredibly hot,

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which is why it's a white dwarf. It's because

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the radiation pushes it into a very

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extreme white part of the spectrum. A bit

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like uh, a lot of the headlights on cars

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these days with LED, ultra white

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LEDs, it's that sort of thing. Um, but for

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different processes it's very hot. That's why

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it radiates the whiteness. Uh, but it

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basically uh, is an object with

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uh, it's in a state of what's

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called electron degeneracy. And that means

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that the electrons

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are uh, the only thing stopping it collapsing

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into something more dense

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like ah, a black hole. So it's this electron

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pressure that uh, sort of stops a

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further collapse. Uh, and

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essentially um, you've got.

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Matter does very, very funny things under

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those circumstances because it's under

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extreme compression. Uh, and

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so you've got basically

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a carbon oxygen rich

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carbon core which uh, in the

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initial stages, uh, as Mark

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says, uh, um, after a very

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long period of initial cooling, that's what

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he says in those initial stages, uh,

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it's liquid, It's a liquid core, a liquid of

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carbon and oxygen. Uh, and

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it's very hard for us to imagine

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that now as that cools it,

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uh, it's when the crystallisation takes

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place, it becomes a lattice of rather than

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a slushy liquid of these Atoms,

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they form a lattice structure which we call a

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crystal. Uh, and

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that uh. So Mark asks

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what's the process of crystallisation? It's

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the cooling of the, of the liquid core

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further. Uh, so uh, under the extreme

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pressure you get basically diamond

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forming, that's what it is. Um,

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and so that crystallisation, it means that

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the core is diamond related.

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Um so uh,

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that's the sort of end product.

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Um, so

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then that process of

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diamond formation actually releases

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heat, what we call latent heat. It releases

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heat and so it slows down the

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star's cooling. Uh, and apparently it slows

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it down by roughly a billion years.

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Uh, and so the

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suggestion, uh, there's a comment here that

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um, I'm looking at that says Gaia data,

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that's the measurement of the positions of

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billions of stars and their colours.

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Recent uh, Gaia data suggests this is a

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common 10 million year long high density

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phase. Uh, but when it,

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when it, when um, when you've, when

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you've basically not quite sure why, there's

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a conflict of numbers there which are

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struggling to understand. But if you've got

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the star cooling delayed by a

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billion years and then

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the cooling phase keeps on going,

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uh, you've got then many tens of billions of

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years before it becomes a cold and dead

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object, uh, which we call a black dwarf.

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Uh, I don't think there are any black dwarfs

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yet because the universe isn't old enough for

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them to, them to be, to have been created.

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Andrew Dunkley: So they're theoretical. But they um,

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might suppose in terms of

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theoretical, they're probable.

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Professor Fred Watson: Yes, that's right. That's about right.

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Andrew Dunkley: Okay.

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Professor Fred Watson: The diamond stars, I mean it's a nice

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concept, isn't it?

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Andrew Dunkley: Yeah. Gee, it's such a. Time frames

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that you just can't, yeah.

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Contemplate. It just makes us seem so tiny

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and small and insignificant, doesn't it?

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Professor Fred Watson: Uh, yes. Although we're important to each

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other.

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Andrew Dunkley: Yeah, that's, that's true. Um, I, I was

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just doing a bit of research while you were

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talking. Apparently they think 97%

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of stars in the Milky Way will become white

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dwarfs.

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Professor Fred Watson: Yeah, that's right. They're, they're, you

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know, they're the ones that go supernova are

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the rarities.

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Andrew Dunkley: That's good though. I mean imagine if 97

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of the stars in the Milky Way became black

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holes. We'd all be in trouble.

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Professor Fred Watson: Yeah.

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Andrew Dunkley: Could be messy.

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Professor Fred Watson: Uh, that, that's right. Yes we

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would, it would be a much more

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um, inhospitable universe.

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Andrew Dunkley: Indeed. Thank you, Mark.

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Hopefully we adequately answered Your

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question.

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Great to hear from you. Uh, we've got an

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audio question now. This one comes from

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Steve.

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Speaker C: Hi guys. Love your podcast. Keeps

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me uh, awake a little later every

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evening listening.

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Steve here from Tin Can Bay

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in Queensland. Very dark sky

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place actually. And my question is to

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do with different sized black holes

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and gravitational gradient.

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Not that I know much about this. I was

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wondering, um, if you fell into a

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smaller black hole, believe this

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specification effect where the

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gravity at one end of your body to the other

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would tear uh, you apart, that if you

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free fell into a

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super large black hole,

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wouldn't the gravitational gradient be

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more even out across the plane and

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you uh, would just free fall into it?

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Can explain that and make

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more sense of it.

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Andrew Dunkley: Thank you, Steve. Uh, Tin Can Bay. What a

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beautifully named place. I love it.

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Professor Fred Watson: Have you ever been, Andrew?

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Andrew Dunkley: I haven't been there, no.

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Professor Fred Watson: No, I haven't either.

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Andrew Dunkley: Yeah, sounds like it's a great place to

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visit, especially at night if it's a dark sky

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area. Fantastic.

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Professor Fred Watson: Yep. Cheque it out.

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Andrew Dunkley: Um, so we're talking about different sized

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black holes and if you fell into them, well,

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we all know what would probably happen. But

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uh, what if it's super large? Uh, is

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its gravitational gradient spread evenly

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and does that mean you could fall into it

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without too much trouble?

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Professor Fred Watson: I think, um, so if you think about the um,

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the gravitational, well the shape of this,

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this sort of vortex that is the black

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hole in gravity. Um, yes,

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for a bigger black hole, ah, black hole, uh,

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it will be less steep. It will

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basically extend over a much wider area than

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for a small black hole and will start

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off less steep because it's, it's a gentler

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slope, um, which means, and

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what that's telling you is the event horizon

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is bigger, uh, for a larger

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black hole, a larger mass black hole, but the

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end product is pretty well all always

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the same. Uh, maybe your

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spaghettification will be a bit gentler, but

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you're always going to end up in a very, very

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steep gravity gradient. Um, and

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yes, I think, um,

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uh, you know, Steve's question, Steve's

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thinking I think is right, that

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the way that gradient changes is what

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uh, tells you how quickly you're going to be

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spaghettified. Um, and it changes

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more slowly for a larger mass black hole than

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for a smaller black hole. But uh,

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you're still going to wind up in deep trou,

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um, you're still going to get spaghettified

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in the end.

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Andrew Dunkley: Yeah, I suppose depending on the size and

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gravity effect of the black hole, it could be

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spaghettified or linguinified

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you know, it could, it could be variables

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like that.

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Professor Fred Watson: It could be. Yes, that's right. Yes. Yeah.

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Andrew Dunkley: Well, I haven't thought to fly pastified.

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That would be. That would be really

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different.

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Professor Fred Watson: Yeah.

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Andrew Dunkley: Uh, very unusual. But, um, I think in the

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movie Interstellar, they broke the laws of

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physics when they actually did successfully

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go through a black hole at one point in that

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film. Um, I think they did. I think they

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described it as a. It was a supermassive

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black hole, but it was very, very well

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tempered, something to that effect.

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Um, but yes, that, that, um. Because what

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they were looking for was only available to

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them, uh, in terms of research on the

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inside of a black hole. And so they had to go

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in there and find what they needed to save

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the world.

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Professor Fred Watson: Yeah, Y.

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Yes, that's right.

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Andrew Dunkley: Great film though. One of my favourites. Uh,

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thank you, Steve. Hopefully we answered, uh,

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your question today on Space Nuts. Uh,

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and you're listening to a Q A edition with

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Andrew Dunkley and Professor Fred Watson

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Watson.

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Speaker C: M. Space Nuts.

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Andrew Dunkley: Okay, uh, next question, Fred Watson. Over

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the years, Fred Watson has explained how

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astronauts orbiting the Earth are affected by

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gravity about the same as us because

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they are in effect continually falling. When

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they leave orbit and head into space, how far

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do they need to travel before they no longer

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feel the effects of gravity? Also,

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uh, when they orbit the moon, is it the same

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as orbiting the Earth? Uh, that one comes

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from Wayne. Hi, Wayne. Thanks for the

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question.

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Professor Fred Watson: Yes. So how far do you need to

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go?

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Andrew Dunkley: I had a question, but it dropped out of my

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head. But, um, uh, I suppose that the first

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point we look at, if you're orbiting Earth,

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you're continually falling, but

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you're still, uh, feeling weightlessness,

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aren't you?

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Professor Fred Watson: Yes. So that's how it works. You're

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being pulled towards the centre of the Earth

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by gravity. Uh, and you're feeling much the

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same gravity as we do on the surface. Uh, but

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what's stopping you from falling is your

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forward motion. You're always, um,

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moving, uh, in an orbit that means

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that you never actually reach the centre of

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the Earth. Uh, which is just as well because

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it's not a nice place. No, um, not really,

340
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but. Okay. So then you, uh, you fire your

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rockets, you do translunar injection or

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whatever that is. Uh,

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wherever you're going, if you're going to the

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moon, it's a translunar injection, that's

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what they call it, which puts you.

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Takes you from the orbit that you're in, a

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circular orbit around the Earth and puts you

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into a different orbit which,

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uh, will carry you out towards the moon.

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Uh, and if you don't do anything, uh,

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as happened with Artemis 2, there were a

352
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couple of minor course corrections, but

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basically that will bring you back to Earth

354
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because you're still in an orbit,

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even though it's a very long thin one. It was

356
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a figure of 8:1 in the case of Artemis 2. But

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you're still in orbit, you're still being

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pulled towards the Earth. Uh, the Earth's

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gravity is

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reducing, uh, as you go further out,

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uh, um, but you're still

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feeling it. And okay, uh, if

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you go out, uh, to Saturn,

364
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um, you're still feeling the Earth's gravity.

365
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Um,

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there comes a time, uh, which is when

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you expand your voyage beyond the

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Earth moon system. There comes a time when

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you're feeling the sun's gravity more so

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of technically in orbit around the sun. And

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that's what happens with interplanetary

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probes. You go to Saturn,

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you're in an orbit, but you're still being

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pulled back towards the sun. And if you don't

375
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do anything when you get to Saturn, like fire

376
00:16:06.470 --> 00:16:08.350
your braking rockets to slow you down, to put

377
00:16:08.350 --> 00:16:10.510
you in orbit around Saturn, if you don't do

378
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anything, you'll wind up going back to the

379
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sun. You'll end up coming back.

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Andrew Dunkley: Is that what's happening with comets and

381
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asteroids?

382
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Professor Fred Watson: Yeah, yeah. They're just feeling the pull of,

383
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so, um, comets in particular. Out there in

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the Oort cloud, they get a little bit of a

385
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nudge. That means that um,

386
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their velocity is not enough to keep them

387
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from falling in towards the sun. Uh,

388
00:16:34.120 --> 00:16:36.960
and so they do. And it takes them a long time

389
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to get in towards the sun. Hundreds of

390
00:16:39.280 --> 00:16:41.680
thousands of years, but they still do it.

391
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They're still in orbit.

392
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Andrew Dunkley: Okay, so how, how far would

393
00:16:46.320 --> 00:16:48.840
you have to go outside the solar system

394
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to not feel that effect?

395
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Or you're always going to feel something

396
00:16:55.400 --> 00:16:55.920
somewhere.

397
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Professor Fred Watson: Yeah, gravity's not something that

398
00:16:59.160 --> 00:17:01.920
disappears. It actually falls

399
00:17:01.920 --> 00:17:04.920
away and uh, effectively becomes zero at

400
00:17:04.920 --> 00:17:07.760
very big distances. But it's still there, as

401
00:17:07.760 --> 00:17:10.520
witnessed by the oak clouds a light year away

402
00:17:10.520 --> 00:17:12.850
or something like that. Um, you know,

403
00:17:13.420 --> 00:17:15.330
um, the,

404
00:17:16.690 --> 00:17:19.570
what eventually happens in interstellar space

405
00:17:19.570 --> 00:17:22.250
is you feel, you still feel the pull of stars

406
00:17:22.250 --> 00:17:24.370
around you, including the sun, but

407
00:17:24.930 --> 00:17:27.689
you're also under the influence of the

408
00:17:27.689 --> 00:17:30.360
galaxy itself. So our,

409
00:17:30.360 --> 00:17:32.850
uh, sun for example, is in orbit around the

410
00:17:32.850 --> 00:17:35.290
galactic centre. It's falling towards the

411
00:17:35.290 --> 00:17:38.060
galactic centre, but its velocity of, uh,

412
00:17:38.060 --> 00:17:40.690
200 kilometres per second,

413
00:17:41.720 --> 00:17:44.620
uh, actually about nearer

414
00:17:44.620 --> 00:17:47.460
to 250 kilometres per second around the

415
00:17:47.460 --> 00:17:49.100
centre of the galaxy. That's what's stopping

416
00:17:49.100 --> 00:17:51.180
it falling in towards the galactic centre

417
00:17:52.300 --> 00:17:54.380
goes around in about 200 million years.

418
00:17:55.020 --> 00:17:58.020
It's weird. Yeah, it is

419
00:17:58.020 --> 00:17:59.940
weird. It's very weird.

420
00:17:59.940 --> 00:18:01.740
Andrew Dunkley: I mean we're talking about that next with

421
00:18:01.740 --> 00:18:04.340
oddities in space, but that's one of them. I

422
00:18:04.340 --> 00:18:06.700
mean we've got this situation where these

423
00:18:06.700 --> 00:18:09.450
things been doing this for billions of years

424
00:18:09.450 --> 00:18:12.410
and that's not going to stop in a hurry.

425
00:18:12.410 --> 00:18:14.850
And, and even when our

426
00:18:15.570 --> 00:18:18.570
solar system ultimately has the

427
00:18:18.570 --> 00:18:21.170
sun go, you know, boom,

428
00:18:21.970 --> 00:18:23.730
it's still going to be happening like that,

429
00:18:24.450 --> 00:18:25.170
is it not?

430
00:18:26.050 --> 00:18:28.530
Professor Fred Watson: Yes, well, I mean the sun will

431
00:18:28.530 --> 00:18:31.250
swell, uh, to possibly

432
00:18:31.650 --> 00:18:33.930
engulf the inner planets, but the centre of

433
00:18:33.930 --> 00:18:36.050
its gravity is still where it is now,

434
00:18:36.340 --> 00:18:39.140
effectively. Um, so yes.

435
00:18:39.700 --> 00:18:42.380
Andrew Dunkley: What about maybe uh, you know, getting

436
00:18:42.380 --> 00:18:44.180
yourself into a Lagrange point?

437
00:18:45.060 --> 00:18:47.980
Professor Fred Watson: Yeah. So that's where those points

438
00:18:47.980 --> 00:18:50.460
are, where gravity and often

439
00:18:50.460 --> 00:18:52.900
centrifugal force balance out.

440
00:18:53.460 --> 00:18:55.380
So you've got this stable point

441
00:18:56.200 --> 00:18:58.860
M. You still. They're not that stable

442
00:18:58.860 --> 00:19:01.700
actually. The, you can tip one way or the

443
00:19:01.700 --> 00:19:03.540
other. It's more like a saddle in the

444
00:19:03.540 --> 00:19:06.260
gravitational pull, but they're still

445
00:19:06.890 --> 00:19:07.450
more stable.

446
00:19:07.530 --> 00:19:09.850
And I was actually going to mention that, um,

447
00:19:09.930 --> 00:19:12.890
that leads then to this idea of the

448
00:19:12.890 --> 00:19:14.490
interplanetary superhighway.

449
00:19:16.730 --> 00:19:19.210
The planets and their Lagrange points are

450
00:19:20.090 --> 00:19:22.890
kind of interlinked by these low energy

451
00:19:22.890 --> 00:19:25.770
pathways through the solar system. So if you

452
00:19:25.770 --> 00:19:28.410
push uh, an object into one of these low

453
00:19:28.490 --> 00:19:30.930
energy pathways, they are feeling the gravity

454
00:19:30.930 --> 00:19:33.440
of not just the sun and the Earth, but the

455
00:19:33.440 --> 00:19:35.680
moon and other planets as well. But they can

456
00:19:35.680 --> 00:19:37.960
wander their way along one of these pathways,

457
00:19:38.580 --> 00:19:40.520
uh, till they get to the other Lagrange

458
00:19:40.520 --> 00:19:42.640
point. And that's something that's been

459
00:19:42.640 --> 00:19:44.600
looked at for slow speed

460
00:19:44.920 --> 00:19:47.920
interplanetary travel, maybe for supply ships

461
00:19:47.920 --> 00:19:49.800
or something like that. But you're going to

462
00:19:49.800 --> 00:19:52.000
take decades to get to wherever you want to

463
00:19:52.000 --> 00:19:52.280
go.

464
00:19:52.360 --> 00:19:55.360
Andrew Dunkley: And by then, um, um, your

465
00:19:55.360 --> 00:19:57.880
iPhone's probably defunct.

466
00:19:58.320 --> 00:20:00.060
Uh, the technology would be too old.

467
00:20:00.060 --> 00:20:02.940
Professor Fred Watson: Yeah, yeah, yeah, yeah.

468
00:20:02.940 --> 00:20:05.860
Andrew Dunkley: Uh, so if you get far enough away from the,

469
00:20:05.860 --> 00:20:08.500
the pull of the Earth and the moon, the sun's

470
00:20:08.500 --> 00:20:09.140
going to grab you.

471
00:20:09.140 --> 00:20:11.140
Professor Fred Watson: You, you feel other things as well. Yeah,

472
00:20:11.140 --> 00:20:12.220
Jupiter's another.

473
00:20:12.220 --> 00:20:15.060
Andrew Dunkley: Oh yeah. Well it, yeah, it does not

474
00:20:15.060 --> 00:20:16.140
like being ignored.

475
00:20:16.540 --> 00:20:17.900
Professor Fred Watson: No it doesn't. That's right.

476
00:20:18.620 --> 00:20:21.500
Andrew Dunkley: In fact, that's another factor in our

477
00:20:21.780 --> 00:20:24.700
uh, solar system that Jupiter, because of its

478
00:20:24.700 --> 00:20:27.540
size and gravitational effect, is

479
00:20:28.420 --> 00:20:30.980
a good barrier for Earth when it comes to

480
00:20:31.940 --> 00:20:34.100
big, um, rocks heading in this direction.

481
00:20:34.420 --> 00:20:37.340
Professor Fred Watson: That's right. That's been um,

482
00:20:37.340 --> 00:20:40.100
postulated as one of the reasons why the

483
00:20:40.100 --> 00:20:42.899
Earth has evolved life because

484
00:20:42.899 --> 00:20:45.180
it's protected to some extent, particularly

485
00:20:45.180 --> 00:20:48.000
by comets. From comets, uh,

486
00:20:48.000 --> 00:20:50.500
by Jupiter, which turns a lot of comets

487
00:20:51.380 --> 00:20:54.140
from having fallen in from the Oort Cloud.

488
00:20:54.140 --> 00:20:55.820
They get grabbed by Jupiter's gravity and

489
00:20:55.820 --> 00:20:57.940
become what we call short period comets.

490
00:20:58.540 --> 00:21:01.480
Uh, so. But I've read papers that

491
00:21:01.480 --> 00:21:04.280
say the opposite is true. Jupiter's effect is

492
00:21:04.280 --> 00:21:07.080
not as protective as we'd like it to be. And

493
00:21:07.080 --> 00:21:09.120
maybe some of Jupiter's

494
00:21:10.160 --> 00:21:12.720
malevolence, uh, is when it redirects comets

495
00:21:12.720 --> 00:21:14.960
into short period orbits and we run into

496
00:21:14.960 --> 00:21:15.280
them.

497
00:21:16.400 --> 00:21:19.280
Andrew Dunkley: Yeah, not nice. Not nice at all.

498
00:21:19.320 --> 00:21:22.200
Um, so basically, doesn't matter where

499
00:21:22.200 --> 00:21:24.160
you go, you're going to be affected by some

500
00:21:24.160 --> 00:21:25.160
sort of gravity?

501
00:21:25.160 --> 00:21:27.340
Professor Fred Watson: That's right. Yes, you will. Even if you're

502
00:21:27.900 --> 00:21:29.940
deep in interstellar space, you'll still be

503
00:21:29.940 --> 00:21:31.700
feeling the effect of the gravity as a whole,

504
00:21:31.700 --> 00:21:32.540
as that

505
00:21:32.540 --> 00:21:35.500
Andrew Dunkley: means weightlessness is a myth in real terms.

506
00:21:35.900 --> 00:21:38.460
Professor Fred Watson: Um, yeah. Yes,

507
00:21:38.860 --> 00:21:41.060
in a sense it is. Uh,

508
00:21:42.380 --> 00:21:45.340
weight needs gravity. Um, and

509
00:21:46.700 --> 00:21:48.620
if you are experiencing forces

510
00:21:49.340 --> 00:21:52.060
that balance that, uh, force of gravity, then

511
00:21:52.060 --> 00:21:53.700
you're weightless and that's what happens

512
00:21:53.700 --> 00:21:55.540
when you're in orbit. There you go.

513
00:21:55.620 --> 00:21:58.340
Andrew Dunkley: All right, Good question. Thanks, Wayne.

514
00:21:58.340 --> 00:22:00.420
Lovely to hear from you. Our final question

515
00:22:00.500 --> 00:22:03.300
in this episode comes from Casey.

516
00:22:03.380 --> 00:22:05.860
Speaker C: Hi, guys, this is Casey from Colorado.

517
00:22:06.260 --> 00:22:08.300
There's a lot of weird stuff in space and I

518
00:22:08.300 --> 00:22:09.780
was wondering what some of your favourite

519
00:22:09.780 --> 00:22:12.780
oddities are. Thanks for the podcast

520
00:22:12.780 --> 00:22:15.140
and shout out to Huw for fixing the audio

521
00:22:15.140 --> 00:22:16.420
submissions. Bye.

522
00:22:17.060 --> 00:22:19.540
Andrew Dunkley: Thank you, Casey. Oh, Huw did some work. My

523
00:22:19.540 --> 00:22:22.280
goodness. Um,

524
00:22:22.430 --> 00:22:25.150
only took a couple of months. Um, no, thanks,

525
00:22:25.150 --> 00:22:27.710
Casey. Uh, oddities in space. I love this

526
00:22:27.710 --> 00:22:30.110
question, uh, because there are many,

527
00:22:30.780 --> 00:22:32.870
uh, if you go through an official list, of

528
00:22:32.870 --> 00:22:34.910
course, number one would be dark matter,

529
00:22:35.070 --> 00:22:36.910
number two would be dark energy.

530
00:22:37.820 --> 00:22:40.370
Um, those are obvious. Um,

531
00:22:41.230 --> 00:22:42.550
have you had a think about this one,

532
00:22:42.550 --> 00:22:43.790
Fred Watson? What have you come up with?

533
00:22:44.030 --> 00:22:45.630
Professor Fred Watson: Well, you know, we've just been talking about

534
00:22:45.830 --> 00:22:47.390
what, Something that's really odd and

535
00:22:47.390 --> 00:22:49.270
counterintuitive. A diamond star?

536
00:22:49.590 --> 00:22:50.150
Andrew Dunkley: Yeah.

537
00:22:50.880 --> 00:22:53.830
Professor Fred Watson: Um, a, uh, metal asteroid. That would

538
00:22:53.830 --> 00:22:56.150
be an oddity. We think Psyche is a metal

539
00:22:56.150 --> 00:22:58.030
asteroid. We'll find out when the Psyche

540
00:22:58.030 --> 00:23:00.880
spacecraft reaches Psyche. I, uh,

541
00:23:00.910 --> 00:23:03.350
think in 2031 or thereabouts. I think it's

542
00:23:03.350 --> 00:23:06.270
got a way to go yet. Uh, maybe not

543
00:23:06.270 --> 00:23:08.870
that far anyway. Sure, it's going to happen.

544
00:23:09.280 --> 00:23:11.110
Um, but I think

545
00:23:14.210 --> 00:23:16.930
some of the coincidences, uh, are

546
00:23:16.930 --> 00:23:19.690
oddities. And the one that always

547
00:23:19.690 --> 00:23:21.890
blows my mind is the coincidence of the sun

548
00:23:21.890 --> 00:23:24.490
and the moon looking to be the same size in

549
00:23:24.490 --> 00:23:27.489
the sky. That's a complete random thing

550
00:23:27.489 --> 00:23:29.250
with no physical

551
00:23:30.050 --> 00:23:32.370
mechanism that has caused that. And you've

552
00:23:32.370 --> 00:23:33.930
got these two objects which are the most

553
00:23:33.930 --> 00:23:35.850
prominent objects in our skies and they

554
00:23:35.850 --> 00:23:37.650
appear to be exactly the same size.

555
00:23:38.280 --> 00:23:40.760
Andrew Dunkley: And it's just a coincidental, just a

556
00:23:40.760 --> 00:23:42.920
coincidence proximity thing, isn't it?

557
00:23:42.920 --> 00:23:43.480
Professor Fred Watson: Very weird.

558
00:23:43.560 --> 00:23:45.760
Andrew Dunkley: Yeah. Actually I've got one that involves the

559
00:23:45.760 --> 00:23:48.240
moon I just, uh, found. And um,

560
00:23:48.440 --> 00:23:50.560
despite the fact that we look at it in the

561
00:23:50.560 --> 00:23:53.440
night sky and it's round, um, they say it's

562
00:23:53.440 --> 00:23:56.200
lemon shaped. Is that true?

563
00:23:56.900 --> 00:23:59.800
Professor Fred Watson: Um, it's

564
00:23:59.800 --> 00:24:02.760
got a slight deviation. Yes, that's right.

565
00:24:03.060 --> 00:24:05.900
Uh, ah, a bulge.

566
00:24:06.220 --> 00:24:07.740
Because it's always feeling,

567
00:24:08.980 --> 00:24:10.940
uh, because it always faces the same

568
00:24:11.980 --> 00:24:14.780
side to the Earth, I think it's slightly

569
00:24:15.020 --> 00:24:16.860
elongated in that direction.

570
00:24:17.180 --> 00:24:17.780
Andrew Dunkley: Okay.

571
00:24:17.780 --> 00:24:19.820
Professor Fred Watson: Um, I think that's the case. But

572
00:24:20.700 --> 00:24:23.500
in the, from the direction

573
00:24:23.500 --> 00:24:26.300
we see it, uh, because that lemon

574
00:24:26.300 --> 00:24:29.300
shape is towards us, what we see

575
00:24:29.300 --> 00:24:31.380
is an object that is almost perfectly

576
00:24:31.380 --> 00:24:34.100
circular. The moon. Very, very,

577
00:24:34.500 --> 00:24:37.060
very, very, uh, perfectly circular.

578
00:24:37.380 --> 00:24:39.260
Andrew Dunkley: And while we're talking about that, because

579
00:24:39.260 --> 00:24:41.340
you just popped into my head while you were

580
00:24:41.340 --> 00:24:43.860
talking, the sun in terms of,

581
00:24:44.920 --> 00:24:47.700
um, being spherical is almost the perfect

582
00:24:47.700 --> 00:24:48.660
circle, isn't it?

583
00:24:48.900 --> 00:24:51.900
Professor Fred Watson: It is, um, it differs from

584
00:24:51.900 --> 00:24:54.340
being spherical by something like 10

585
00:24:54.420 --> 00:24:57.060
kilometres and it's 1.4 million

586
00:24:57.060 --> 00:25:00.020
kilometres in diameter. That's right. And

587
00:25:00.020 --> 00:25:02.380
actually that raises another oddity in my

588
00:25:02.380 --> 00:25:05.180
mind, uh, which we've talked about many

589
00:25:05.180 --> 00:25:07.900
times. The mountains on neutron stars. Oh,

590
00:25:07.900 --> 00:25:10.180
yes. A few millimetres high.

591
00:25:10.420 --> 00:25:12.740
Andrew Dunkley: Yeah. That's just crazy, isn't it?

592
00:25:13.860 --> 00:25:16.580
Yeah. M. If you do

593
00:25:16.580 --> 00:25:18.260
Google searches for these things, it's

594
00:25:18.340 --> 00:25:21.260
millions of them. But uh, you know, if

595
00:25:21.260 --> 00:25:23.080
we stick to our solar system for a moment,

596
00:25:23.080 --> 00:25:25.860
um, a day on Mercury

597
00:25:26.310 --> 00:25:27.670
is twice as long as a year.

598
00:25:28.390 --> 00:25:29.430
Professor Fred Watson: Yes, that's right.

599
00:25:29.670 --> 00:25:32.520
Andrew Dunkley: Is that because of its, um, uh,

600
00:25:32.520 --> 00:25:35.270
what do you call it, um, tidal locking? Yes,

601
00:25:35.270 --> 00:25:36.430
tidal locking does sound.

602
00:25:36.430 --> 00:25:39.390
Professor Fred Watson: It's not quite tidally locked, but there's a

603
00:25:39.390 --> 00:25:41.510
relationship between the rotation and the

604
00:25:41.510 --> 00:25:44.030
revolution period, which is what you've said.

605
00:25:44.030 --> 00:25:46.750
Yeah, very weird. Yeah. Some of the

606
00:25:46.750 --> 00:25:48.710
planets have very weird things. I mean,

607
00:25:49.060 --> 00:25:51.790
um, Uranus on its side, that's an

608
00:25:51.790 --> 00:25:54.700
oddity. Um, that's very

609
00:25:54.700 --> 00:25:56.820
strange. But we think that's caused by a

610
00:25:56.820 --> 00:25:58.540
collision in the early solar system.

611
00:25:58.700 --> 00:26:01.660
Andrew Dunkley: Yeah. Uh, all the planets

612
00:26:01.660 --> 00:26:03.820
could fit between Earth and the moon.

613
00:26:03.820 --> 00:26:04.780
Professor Fred Watson: Yes, that's right.

614
00:26:04.940 --> 00:26:06.940
Andrew Dunkley: I mean that just blows my mind.

615
00:26:10.140 --> 00:26:12.460
Professor Fred Watson: It's actually. Go ahead.

616
00:26:12.540 --> 00:26:14.100
Andrew Dunkley: No, uh, that would make for some very

617
00:26:14.100 --> 00:26:16.300
interesting nights of observation, I imagine.

618
00:26:16.620 --> 00:26:19.160
Professor Fred Watson: Yeah. And it's an issue. It's um,

619
00:26:19.520 --> 00:26:22.400
quite interesting because the moon's, you

620
00:26:22.400 --> 00:26:24.560
know, the moon's orbit around the Earth is

621
00:26:24.560 --> 00:26:27.280
not circular, so sometimes it's nearer than

622
00:26:27.280 --> 00:26:29.800
at others. Perigee is when it's at its

623
00:26:29.800 --> 00:26:32.080
closest apogee is when it's at its furthest.

624
00:26:32.820 --> 00:26:35.760
Uh, the planets. The eight planets. Sorry,

625
00:26:35.760 --> 00:26:37.960
seven planets. Because the Earth's not part

626
00:26:37.960 --> 00:26:40.480
of it. Uh, they will only

627
00:26:40.800 --> 00:26:43.720
fit between the Earth and the Moon when

628
00:26:43.720 --> 00:26:46.120
the Moon is near apogee, if it's near

629
00:26:46.120 --> 00:26:48.160
perigee, you can't squeeze them in and it

630
00:26:48.160 --> 00:26:49.880
becomes a bit ugly, really.

631
00:26:49.960 --> 00:26:52.960
Andrew Dunkley: Yeah, I imagine so, yeah. Uh, I like

632
00:26:52.960 --> 00:26:55.680
this one. A teaspoon of neutron star

633
00:26:55.680 --> 00:26:57.640
weighs the same as the human population.

634
00:26:59.720 --> 00:27:01.160
I don't know how they figured that out.

635
00:27:01.860 --> 00:27:04.860
Professor Fred Watson: Uh, yes, yeah, uh,

636
00:27:04.860 --> 00:27:05.480
that's right.

637
00:27:06.920 --> 00:27:09.240
Andrew Dunkley: But, yeah, they're very heavy. Heavy.

638
00:27:10.040 --> 00:27:12.360
Professor Fred Watson: The one I like, the numerical one that I like

639
00:27:12.840 --> 00:27:15.000
is. And again, it's completely

640
00:27:15.480 --> 00:27:18.320
bizarre. It's got no reason for it. But the

641
00:27:18.320 --> 00:27:20.560
number of astronomical units and an

642
00:27:20.560 --> 00:27:22.240
astronomical unit is the distance from the

643
00:27:22.240 --> 00:27:25.200
sun to the earth, 150 million million

644
00:27:25.200 --> 00:27:27.920
kilometres. The number of astronomical units

645
00:27:27.920 --> 00:27:30.200
in a light year is almost

646
00:27:30.360 --> 00:27:33.280
exactly the same as the number of inches in

647
00:27:33.280 --> 00:27:33.880
a mile.

648
00:27:35.960 --> 00:27:38.730
It's very, very weird. 63,000 is the

649
00:27:38.730 --> 00:27:40.690
number, so there's a few digits that don't

650
00:27:40.690 --> 00:27:41.170
fit, but.

651
00:27:41.170 --> 00:27:44.130
Andrew Dunkley: Yeah, that's incredible. Uh, and then, and

652
00:27:44.130 --> 00:27:46.300
then there's these ones that sound, um,

653
00:27:46.610 --> 00:27:49.530
weird, but so logical when you

654
00:27:49.530 --> 00:27:51.730
explain it. That there are stars in the

655
00:27:51.730 --> 00:27:53.290
universe that we will never see.

656
00:27:54.890 --> 00:27:57.330
Professor Fred Watson: Yeah, uh, yes, because the light will never

657
00:27:57.330 --> 00:27:58.330
reach us. That's right.

658
00:27:59.130 --> 00:28:01.770
Andrew Dunkley: And that's probably why we'll never, ever

659
00:28:02.250 --> 00:28:04.980
find alien life too far away.

660
00:28:06.260 --> 00:28:09.100
Professor Fred Watson: Maybe. Maybe. Maybe the

661
00:28:09.100 --> 00:28:10.420
SETI people aren't giving up.

662
00:28:10.500 --> 00:28:13.220
Andrew Dunkley: No, they're not. Uh, now, I did say that,

663
00:28:13.480 --> 00:28:16.460
um, um, a day on Mercury is twice as long

664
00:28:16.460 --> 00:28:18.740
as a year. But on Venus,

665
00:28:19.700 --> 00:28:22.660
I think, um, it's a similar

666
00:28:22.660 --> 00:28:25.380
storey, isn't it? A day on Venus is longer

667
00:28:25.380 --> 00:28:25.940
than a year.

668
00:28:26.340 --> 00:28:27.860
Professor Fred Watson: Very long. Yeah. I can't remember the

669
00:28:27.860 --> 00:28:30.490
details, but Venus basically rotates the

670
00:28:30.490 --> 00:28:32.730
wrong way around. Uh, so

671
00:28:34.170 --> 00:28:36.090
its North Pole is facing downwards.

672
00:28:37.450 --> 00:28:40.370
That's what gives you the funny rotation. You

673
00:28:40.370 --> 00:28:43.210
define the north and south poles as

674
00:28:43.210 --> 00:28:45.930
being the direction or the point on a

675
00:28:45.930 --> 00:28:48.210
planet where, if you're looking at it from

676
00:28:48.210 --> 00:28:50.570
above, it's rotating anti clockwise.

677
00:28:51.370 --> 00:28:54.210
Because virtually everything in the solar

678
00:28:54.210 --> 00:28:56.490
system is rotating and revolving anti

679
00:28:56.490 --> 00:28:58.530
clockwise as seen from above the. The North

680
00:28:58.530 --> 00:29:01.010
Pole. Weird.

681
00:29:01.330 --> 00:29:03.650
Andrew Dunkley: Oh, you like this one, Casey? Neptune has

682
00:29:03.810 --> 00:29:05.930
only, uh, completed one orbit since it was

683
00:29:05.930 --> 00:29:08.770
discovered. M Very

684
00:29:08.770 --> 00:29:11.730
quirky, very quirky. And look, there must

685
00:29:11.730 --> 00:29:14.050
be billions of these.

686
00:29:14.530 --> 00:29:17.330
Like, um, you know, the, the weirdness of

687
00:29:17.330 --> 00:29:20.090
rogue planets or, um. Yeah, or the sun

688
00:29:20.090 --> 00:29:21.890
losing a billion kilos per second.

689
00:29:23.570 --> 00:29:24.290
Professor Fred Watson: That's right, yes.

690
00:29:24.290 --> 00:29:26.170
Andrew Dunkley: We found out the secret to that somebody

691
00:29:26.170 --> 00:29:27.800
could make billions of dollars on

692
00:29:27.800 --> 00:29:30.800
Professor Fred Watson: Earth, I reckon needs quite high

693
00:29:30.800 --> 00:29:31.920
temperatures to do that.

694
00:29:32.000 --> 00:29:34.880
Andrew Dunkley: Yeah, yeah. Um, and the list goes on.

695
00:29:34.880 --> 00:29:35.600
You got any more?

696
00:29:36.940 --> 00:29:39.000
Professor Fred Watson: Uh, well, you know, even black holes are

697
00:29:39.000 --> 00:29:41.960
things so weird. And the fact

698
00:29:41.960 --> 00:29:43.440
that we can actually, here's another

699
00:29:43.520 --> 00:29:45.200
statistic that's mind blowing.

700
00:29:45.700 --> 00:29:48.640
Um, it's the, the

701
00:29:48.640 --> 00:29:50.860
ligo, um,

702
00:29:50.860 --> 00:29:53.400
interferometer, which measures gravitational

703
00:29:53.400 --> 00:29:56.010
waves. The accuracy that we

704
00:29:56.010 --> 00:29:58.890
position it or know the mirrors to

705
00:29:59.210 --> 00:30:01.130
is something like a thousandth of the

706
00:30:01.130 --> 00:30:04.010
diameter of a proton. It's just incredible.

707
00:30:04.010 --> 00:30:06.410
But that's technology rather than space

708
00:30:06.410 --> 00:30:09.210
oddities really. That's technology. Yeah,

709
00:30:09.370 --> 00:30:10.730
that blows my mind too.

710
00:30:11.770 --> 00:30:14.570
Andrew Dunkley: And another one that's um, not talked about

711
00:30:14.570 --> 00:30:16.850
much. But our days are getting longer. I

712
00:30:16.850 --> 00:30:18.610
think there was an official report not so

713
00:30:18.610 --> 00:30:21.500
long ago about uh, the new length of a,

714
00:30:21.730 --> 00:30:23.690
of a day on Earth. But they uh, are getting

715
00:30:23.690 --> 00:30:26.330
longer because our rotation's

716
00:30:26.330 --> 00:30:27.810
slowing. Is that what it is?

717
00:30:28.130 --> 00:30:30.410
Professor Fred Watson: Yeah, it actually speeds up occasionally as

718
00:30:30.410 --> 00:30:33.290
well due to probably the movement of

719
00:30:33.290 --> 00:30:35.490
ice and things of that sort. But the overall

720
00:30:35.490 --> 00:30:37.889
trend is definitely slowing of the rotation.

721
00:30:38.370 --> 00:30:40.440
Andrew Dunkley: Yeah, there are so many of them, Casey.

722
00:30:40.440 --> 00:30:43.440
Um, and if, if anybody comes uh,

723
00:30:43.650 --> 00:30:45.330
across one they'd like to ask us about,

724
00:30:45.410 --> 00:30:47.770
please, uh, please send it in. But uh, thanks

725
00:30:47.770 --> 00:30:48.830
Casey. That was a lot of fun.

726
00:30:49.620 --> 00:30:51.820
Uh, and uh, that brings us to the end of the

727
00:30:51.820 --> 00:30:52.660
show, Fred Watson.

728
00:30:53.460 --> 00:30:55.940
Professor Fred Watson: Yes. Another show in the bag.

729
00:30:55.940 --> 00:30:58.860
Andrew Dunkley: And yeah, we're in the can as you, you know.

730
00:30:58.860 --> 00:31:00.420
That's the shop talk way of saying it.

731
00:31:00.420 --> 00:31:03.300
Professor Fred Watson: Shop talk. Yes, in the can. In the can.

732
00:31:03.340 --> 00:31:05.460
Um, and hopefully there'll be many more,

733
00:31:05.460 --> 00:31:05.940
Andrew.

734
00:31:06.180 --> 00:31:08.700
Andrew Dunkley: That would be lovely. Uh, we'll, we'll catch

735
00:31:08.700 --> 00:31:11.460
you on the next one in uh, a few days time.

736
00:31:11.540 --> 00:31:12.220
Fred Watson, thank you.

737
00:31:12.220 --> 00:31:14.180
Professor Fred Watson: Sounds like it. Thanks a lot. Take care.

738
00:31:14.340 --> 00:31:15.980
Andrew Dunkley: Professor Fred Watson Watson, astronomer at

739
00:31:15.980 --> 00:31:18.400
large. And thanks to Huw in the studio, uh,

740
00:31:18.400 --> 00:31:21.170
who couldn't be with us today due to

741
00:31:21.330 --> 00:31:24.090
some kind of oddity, a space

742
00:31:24.090 --> 00:31:26.640
oddity. Um, and don't uh,

743
00:31:26.890 --> 00:31:29.500
forget to visit us online at our website, uh,

744
00:31:29.500 --> 00:31:32.090
or on social media and send us your questions

745
00:31:32.090 --> 00:31:34.570
via the Ask me anything link at the top of

746
00:31:34.570 --> 00:31:37.530
our webpage, uh, in audio

747
00:31:37.530 --> 00:31:40.460
form or uh, as a text. And uh,

748
00:31:40.460 --> 00:31:42.170
don't forget to tell us who you are and where

749
00:31:42.170 --> 00:31:44.010
you're from. Always lovely to hear from you,

750
00:31:44.010 --> 00:31:46.540
wherever you are, are in the world and from

751
00:31:46.540 --> 00:31:48.020
me, Andrew Dunkley. Thanks for your company.

752
00:31:48.020 --> 00:31:50.260
We'll catch you on the next episode of Space

753
00:31:50.260 --> 00:31:53.260
Nuts. Bye bye. You've

754
00:31:53.260 --> 00:31:55.660
been listening to the Space Nuts podcast

755
00:31:57.260 --> 00:31:59.980
available at Apple Podcasts, Spotify,

756
00:32:00.220 --> 00:32:02.980
iHeartRadio or your favourite podcast

757
00:32:02.980 --> 00:32:04.700
player. You can also stream on

758
00:32:04.700 --> 00:32:06.980
demand@bytes.com this

759
00:32:06.980 --> 00:32:09.380
Professor Fred Watson: has been another quality podcast production

760
00:32:09.380 --> 00:32:10.860
from bytes.com.