Exploring Moons with Atmospheres, Hot Jupiters, and the Mysteries of Black Holes

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Andrew Dunkley: Hello again and thank you for joining us on

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yet another episode of Space Nuts. I don't

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know what we're up to.652.

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Blimey. And we only started yesterday.

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Uh, coming up in this Q and A episode, we

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will be answering questions about, uh, moons

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with atmospheres, secret

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astronomy. This is a fascinating question.

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Uh, we've also got, uh, a question about hot

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Jupiters. We've talked about them before. And

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a very rare, never before

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asked black hole question that's

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coming up in this Q and A edition of space

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nuts. 15 seconds.

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Professor Fred Watson: Guidance is internal. 10,

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9, ignition sequence start. Uh,

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space nuts. 5, 4, 3, 2. 1, 2,

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

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Andrew Dunkley: Space nuts.

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Professor Fred Watson: Astronauts report it feels good.

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Andrew Dunkley: Joining us again to resolve all of that is

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Professor Fred Watson Watson, astronomer at

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large. Hi, Fred Watson.

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Professor Fred Watson: Hello, Andrew. How are you? Good to see you

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again.

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Andrew Dunkley: I'm as well as I was the last time you saw

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me.

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Professor Fred Watson: Yes. All those years ago. That's right, yeah.

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Andrew Dunkley: Minutes or seconds, whichever comes first.

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Uh, we've got some good questions today and,

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uh, I thought we might just get straight into

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it if you're, uh, ready to.

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Oh, no, I've got an announcement.

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Professor Fred Watson: Oh, yes, Better do that then.

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Andrew Dunkley: It's a bit of shameless self promotion. I've

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finally released my science fiction trilogy.

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Yes, it's out there. Um, I'm just putting the

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final touches on a few bits and bobs. But the

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ebook is out. Uh, the paperback

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should be out by the time you hear this.

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Um, unless you're watching us live on

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YouTube.

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Professor Fred Watson: Hello.

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Andrew Dunkley: It's called the Human Epoch.

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M which I did look up to see if there are

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any other science fiction books with that

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name, and there are not. So the human

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epoch, parts 1, 2 and 3. I released them all

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at once.

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Andrew Dunkley: Oops.

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Andrew Dunkley: I, uh, nearly released the microphone. Yeah,

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all at once. I thought, I'm gonna write the

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whole thing and release it as a batch rather

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than write one book and then

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release it and then make people wait a year.

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Now the whole bang lot's out there already

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on its way.

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Professor Fred Watson: Seasons one, two and three.

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Andrew Dunkley: Yes, exactly. I hope people enjoy it. Can't

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wait to get the feedback. Good, bad or

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indifferent. So the Human Epoch.

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Professor Fred Watson: Look for it.

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Andrew Dunkley: Uh, and you should be able to order it from

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bookshops. I don't know. I don't know how it

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works. Um, but you know, looking

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at the cost of printing and the

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sharing of spoils, um, if you

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sell a book for 20 bucks these days, you

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might get two or three dollars out of that.

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It's a Tough industry.

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Professor Fred Watson: Very. Yeah.

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Andrew Dunkley: I mean, you've really got to sell

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m tens of thousands of books to even scratch

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the surface. Which I have not done.

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Professor Fred Watson: Yeah, neither have I.

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Andrew Dunkley: No, no. But anyway, I

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thought I'd give it a mention. I've mentioned

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that I was writing it times. I thought I

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might as well people. It's out there. So

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there. That's, um, done.

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Professor Fred Watson: So you're not emulating Douglas Adams with a

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trilogy in four parts?

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Andrew Dunkley: No, but, you know, I

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might. Yeah, I might continue the

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storey because I became very. Isn't.

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Andrew Dunkley: Uh.

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Andrew Dunkley: I don't know if this happens to other

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authors. I'm sure it does.

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Professor Fred Watson: Oh, there you are.

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Andrew Dunkley: It happens to Earth.

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Professor Fred Watson: Yes, it does. He's a bit late.

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Andrew Dunkley: We could have used him in the last episode.

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Professor Fred Watson: We could. That's right. With the dogs.

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Andrew Dunkley: Um, you get a bit attached to some of

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the characters you create.

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Professor Fred Watson: Yes. I believe that happens when you write

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fiction.

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Andrew Dunkley: Um, the main character in this trilogy,

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um, I've come to adore. I really. I love his

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attitude. That's all I say.

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Professor Fred Watson: Okay. All right.

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Andrew Dunkley: Okay. He's

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a different kind of character.

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Professor Fred Watson: Is he based on anybody real?

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Andrew Dunkley: No, I made him up. Um, and I made him

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Canadian. Uh, I don't know why. I just did.

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Professor Fred Watson: I just thought Canadian.

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Andrew Dunkley: Canadians never get much of a mention in

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science fiction novels. So I thought, I'll

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make my hero a Canadian.

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Professor Fred Watson: Good on you. Yeah.

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Andrew Dunkley: All right.

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Professor Fred Watson: Before we do that, I better just go and see

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what's, um. Because I'm home alone at the

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moment. Jordy, I won't be a sec.

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All right?

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Andrew Dunkley: Okay. This doesn't happen very often. He

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could have done that while I was spruiking

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the book, you know, because, um, that would

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have been a nice filler. But now he's

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just left me swinging in the breeze.

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Which, um, happens occasionally.

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This used to happen on radio. I remember

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once, uh, years ago, um, we were

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expecting some guests, so I played an

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appropriate song. I think they were circus

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performers. And I played

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circus by Britney Spears in the hope that

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they would actually arrive while the song was

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on. And, uh, I got lucky. They

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walked in the door just as it was finishing.

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So I got the interview on air in time. It's

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sometimes a bit scary like that. Anyway,

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welcome, uh, back, Fred Watson. Is Jordie

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okay?

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Professor Fred Watson: Yes. I don't know what was causing

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the howling. Uh, ruckus.

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Andrew Dunkley: A butterfly, probably.

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Professor Fred Watson: Could have been. Honestly, it's that level

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that sets him off. You know, a leaf

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moves two, uh, hundred metres away across

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the forest and off he goes. That's right.

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Andrew Dunkley: He could probably use a GPS collar.

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Professor Fred Watson: There were times when he could use a muzzle,

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I think to speak.

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Andrew Dunkley: Um, now let's get into some questions. I

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think that's why we're here.

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Professor Fred Watson: Oh, I suppose it is, yes. Yes.

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Andrew Dunkley: Um, so first question comes from Chris

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in Exmouth in the uk. Just

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wondering, could a moon ever have

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an atmosphere and is it possible for a moon

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to be close enough to a planet to share

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an atmosphere? Really enjoy the show. Thank,

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uh, you Chris for sending that in. Um,

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look, we already know in our solar system

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there are moons with atmospheres and I do

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believe they do share their stuff with their

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home planets, some of them.

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Professor Fred Watson: Uh, correct. That's right. Although

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it's sort of um, probably not quite

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what Chris has, his mind. So yes. Uh, I mean

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the classic example is Saturn's moon Titan,

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that has a very thick atmosphere,

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um, atmospheric pressure I think one and a

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half times that of the Earth. It's a dense

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atmosphere and um, also

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opaque because it's rich in um,

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ah, hydrocarbons. The same

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stuff that makes smog in a city. Uh, is why

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we can't see through Titan's atmosphere. So

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yes, a moon can have an atmosphere, um,

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but you can't have a situation where

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uh, you had a planet and a

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moon which were sort of embedded in a much

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larger dense atmosphere. Uh,

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and that's because the, you basically

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slow down the moon as it orbits the planet,

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uh, and it doesn't last very long. Uh, in

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fact that's what brings satellites down uh,

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from orbit. Low Earth orbit above the Earth.

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They are slowed down by the Earth's

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atmosphere, even though it's very tenuous up

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there. And uh, nevertheless it slows them

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down and they fall deeper into the atmosphere

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and the deceleration continues.

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But the example that you've mentioned is the

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one that came to mind when I read this

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question as well. Uh, which is

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the dwarf planet Pluto, uh,

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which has a large moon. It's uh,

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about half the size of Pluto actually. It's

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called Charon, uh, or Charon, not

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Charon. Some people call it Charon.

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Andrew Dunkley: They do.

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Professor Fred Watson: Charon, Shaz for short.

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Shaza. Yeah, um,

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it's uh, it's a large moon, as

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I said, half the size of Pluto.

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Uh, and so they are in a sense a

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binary dwarf planet system because

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they orbit around a point which

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is outside the body of Pluto, uh,

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which is the kind of definition of a binary

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system, something orbiting around a common

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centre of gravity. Uh, so you've

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got that ah, unusual situation to start

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with, but um,

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it Appears that because of that

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geometry,

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the atmosphere of

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Pluto, which is very, very thin, but it is

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there. I was once helping a project that

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measured the atmosphere of Pluto not from

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space, but by Pluto passing in front of a

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star as observed with the Anglo Australian

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telescope. We could see it dimmed gradually,

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the light of the star rather than just

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switching off as it would have been if

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there'd been no atmosphere. So, uh, that

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atmosphere is mostly nitroge gas,

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uh, or the part that's

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escaping. Uh, and

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apparently it is basically

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captured by Charon. There's

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this flow of the nitrogen

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from Pluto to its dwarf

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planet companion. Um,

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there's probably something similar happens

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with the Earth and Moon, but very, very much

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less intense. Uh, there's probably a

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bit of gas transfer, uh, from

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the Earth, uh, to the Moon. Given that

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the pressure of the Earth's atmosphere

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doesn't just stop suddenly, it falls away

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very gradually. And in fact there are some of

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the molecules of the Earth's atmosphere that

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are out at the distance of the Moon. Uh, so

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they probably do exchange, you

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know, some low levels of gas, but

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not very much. And it is, yes, it's

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a different situation from perhaps what Chris

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had in mind with an atmosphere, with a planet

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and its moon both orbiting within it.

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Andrew Dunkley: Yeah, I understand what he was saying. Uh,

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and as you suggested, um, it

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would be an impossible situation. Although

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we do see, I think around the gas giants,

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some of those planets, particularly the ice

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worlds, do shed some of their

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material, which is picked up by

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um, um, the gas giant, I think.

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Is it Enceladus?

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Professor Fred Watson: Uh, yeah, that forms, um, that's correct.

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So that's solid matter. Actually it's the

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ice crystals that come from Enceladus

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Ocean. They form, uh, Saturn's E

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ring, uh, which is a very, um,

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non dense, very, uh, rarefied ring.

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One. I think it's the outermost ring of

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Saturn. Um, and it's basically,

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uh, the orbit of uh, Enceladus is embedded in

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that. So, yes, that's a sort of similar sort

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of situation. Yeah, that's right.

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Andrew Dunkley: It's not sharing atmosphere, but it's sharing

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material in a way.

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So, uh, the answer to both of your points,

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Chris, is definite. Yes, um,

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but no, in terms of them both sharing the

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same atmosphere. Hold us,

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Bolus. As we say so. Yeah, but great

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question, uh, Christian Exmouth. Where's

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Exmouth, Fred Watson?

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Professor Fred Watson: Uh, down in Devon. It's a lovely part of the

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country. Uh, and um, it's

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uh, not far from Exeter. The River X

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runs through both of them, as you'd expect.

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Andrew Dunkley: Uh, and the River X owned by Elon

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Musk.

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Professor Fred Watson: Probably, yes. It's spelled

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slightly differently from Elon Musk's X, but

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yes, probably still the same thing.

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Andrew Dunkley: Thanks for the question, Chris.

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Next question comes from, uh, somebody

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who's keeping their name a secret. And it's,

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uh, it's about secret astronomy. Oh, hang

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on, That's. I've got to change pages. Here we

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go. Here we go.

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Professor Fred Watson: I have a question about secret

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astronomy. We know that gamma

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ray bursts were first detected by spy

291
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satellites looking for nuclear testing. We

292
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know that satellites use star tracking and

293
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star catalogues for calculating their

294
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position. And we, uh, know that the Nancy

295
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Grace Roman launching, hopefully in August,

296
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uses, um, is built out of a,

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um, spy satellite the National Reconnaissance

298
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Office, the US Uh spy satellite agency,

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donated to NASA because they weren't going to

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launch it. They donated two and only one is

301
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being used yet. And we know that the Space

302
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Force released, um, a bunch of observational

303
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data around bolides to, um, help with

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planetary defence and asteroid detection

305
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and understanding. So by their nature, spy

306
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satellites tend to point at the Earth. Um,

307
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but obviously they push into a lot of

308
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astronomy and astronomy adjacent, um, things.

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I just wondered if you could speculate, given

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their budgets and um,

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constantly improving capabilities, where they

312
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might be ahead of public astronomy or running

313
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into things that, um. Uh,

314
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yeah, it might be pretty interesting in a few

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years. Thank you so much.

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Andrew Dunkley: Thank you for the question.

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Professor Fred Watson: Um,

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Andrew Dunkley: yeah, I don't know who that was, but, um.

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That's okay. Happens from time to time. But

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interesting, uh, question, Fred Watson.

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Professor Fred Watson: Really, it's, uh, not just an interesting

322
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question, but a very well posed one as well.

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Because everything our anonymous questioner

324
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said is true. Uh, and so we are being

325
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invited to speculate on what, what else

326
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might be up and running. Uh, we didn't know

327
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for a long time that there were two more

328
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Hubble telescopes, uh, because,

329
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you know, the company kept their. Built

330
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it. I think it might have been perkinelmer.

331
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I'm, um, not sure. But they kept their cards

332
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very close to their chest, uh, in terms

333
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of, uh, the existence of the Hubble

334
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telescope. But it turned out subsequently we

335
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found out there were two more built for

336
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surveillance. Um, something else

337
00:13:51.260 --> 00:13:54.120
that did find its way into astronomy

338
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that was originally secret was, um,

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President Reagan's Star wars technology,

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uh, which, um, required

341
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adaptive optics. And those are optical

342
00:14:05.480 --> 00:14:08.380
surfaces that change in response to, um,

343
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basically things like, um,

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uh, scintillation in the atmosphere or

345
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twinkling for a star. So that adaptive

346
00:14:16.920 --> 00:14:19.600
optics technology is now used very commonly

347
00:14:19.600 --> 00:14:22.030
in astronomy. Uh, it's not Used

348
00:14:22.510 --> 00:14:25.470
here in Australia we don't have a

349
00:14:25.470 --> 00:14:28.040
site that is naturally good enough um,

350
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to be able to compensate for um,

351
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this um, atmospheric turbulence. Whereas some

352
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of the better sites in the world like Mauna

353
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Kea in Hawaii and Ceropa

354
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Paranal, uh, in Chile, they do. And

355
00:14:41.510 --> 00:14:44.350
so they use um, adaptive optics

356
00:14:44.350 --> 00:14:46.990
very, very uh, commonly for their work.

357
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Basically allows you to take out the

358
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twinkling of a star which is something that

359
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ruins the images as you see them through

360
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telescopes. Uh and um,

361
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as I said, came from Star wars technology.

362
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Uh, that technology by the way, this is uh.

363
00:15:01.760 --> 00:15:04.050
Not really along the lines of the question

364
00:15:04.050 --> 00:15:06.730
but uh. It's leapfrogged as well from

365
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astronomy into um,

366
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ophthalmology. So uh, people are now using

367
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adaptive optics to compensate for

368
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the turbulence inside your eye

369
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when they're doing sort of retinoscopy and

370
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things like that. Uh, so that adaptive optics

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technology is now uh, gone from

372
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defence through astronomy and is

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now um, being developed for uh,

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health reasons, which is very, very good.

375
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Andrew Dunkley: Don't know if it's quite the same thing but

376
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my optometrist was telling me they've

377
00:15:40.270 --> 00:15:42.590
invented a new um, kind of

378
00:15:42.790 --> 00:15:45.430
um, lens that replaces human

379
00:15:45.430 --> 00:15:47.630
lens that can now

380
00:15:49.120 --> 00:15:51.920
do the same thing as a human lens. Like okay,

381
00:15:52.480 --> 00:15:54.600
when you have a cataract operation they

382
00:15:54.600 --> 00:15:56.680
replace the human lens. That's all fogged up

383
00:15:56.680 --> 00:15:59.520
with generally a plastic lens of some

384
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kind. But it was a fixed lens. It could only

385
00:16:02.320 --> 00:16:05.240
do one thing. They've now advanced the

386
00:16:05.240 --> 00:16:07.600
technology to the point where they can put a

387
00:16:07.600 --> 00:16:10.600
lens in that will be able to

388
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be controlled by your brain and give you

389
00:16:13.850 --> 00:16:15.210
various focal lengths.

390
00:16:15.450 --> 00:16:15.890
Professor Fred Watson: Yeah.

391
00:16:15.890 --> 00:16:17.130
Andrew Dunkley: Which I think is amazing.

392
00:16:17.290 --> 00:16:19.250
Professor Fred Watson: It's what you. What your eye naturally does.

393
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It's called accommodation you that the eye

394
00:16:21.410 --> 00:16:23.290
accommodates to different distances by

395
00:16:23.290 --> 00:16:25.810
changing the shape of the lens. Yeah, yeah.

396
00:16:25.810 --> 00:16:28.530
So um, that's pretty. Yes. Quite remarkable

397
00:16:28.530 --> 00:16:31.530
and um. Would be a real breakthrough for

398
00:16:31.730 --> 00:16:34.450
um. You know, for vision, uh, for poor

399
00:16:34.450 --> 00:16:34.810
vision.

400
00:16:34.810 --> 00:16:36.490
Anyway, we've strayed off the topic here. We

401
00:16:36.490 --> 00:16:38.340
have a bit and uh.

402
00:16:38.340 --> 00:16:40.890
Andrew Dunkley: I do, I'm sure never happens usually.

403
00:16:43.010 --> 00:16:45.750
Professor Fred Watson: I'm sure that um. Uh. Our uh.

404
00:16:45.750 --> 00:16:47.930
Listener is on the money suggesting that

405
00:16:47.930 --> 00:16:50.690
there are technologies that are being used

406
00:16:51.090 --> 00:16:52.910
in secrets, um.

407
00:16:53.650 --> 00:16:53.870
Professor Fred Watson: Ah.

408
00:16:53.870 --> 00:16:56.290
Professor Fred Watson: Or restricted environments.

409
00:16:56.770 --> 00:16:59.730
Uh, that would be of great

410
00:16:59.730 --> 00:17:02.670
value for astronomy. I uh.

411
00:17:02.770 --> 00:17:05.170
Guess the kind of thing that comes to mind is

412
00:17:05.890 --> 00:17:08.410
quantum detectors and. And things of that

413
00:17:08.410 --> 00:17:11.330
sort. Um, there is no. I don't think there's

414
00:17:11.330 --> 00:17:14.210
any equivalent uh, for example in the

415
00:17:14.210 --> 00:17:16.690
field of gravitational wave astronomy. I

416
00:17:16.690 --> 00:17:18.050
don't think there's anything that the

417
00:17:18.050 --> 00:17:19.850
military are doing that could feed into that.

418
00:17:19.850 --> 00:17:21.730
Although quantum optics are being used in

419
00:17:21.730 --> 00:17:24.690
that now. So, um, I

420
00:17:24.690 --> 00:17:26.930
suspect it's in, you know, in relation to the

421
00:17:26.930 --> 00:17:29.440
tools that are developed for, uh,

422
00:17:30.090 --> 00:17:32.300
our observations. Um,

423
00:17:32.730 --> 00:17:35.490
we owe infrared detectors,

424
00:17:35.650 --> 00:17:37.770
the things that see redder than red light or

425
00:17:37.770 --> 00:17:40.210
heat radiation. We owe them to the military.

426
00:17:40.210 --> 00:17:43.110
That's a spin off from military work. Um,

427
00:17:43.110 --> 00:17:46.050
I do remember, uh, one of the first

428
00:17:46.050 --> 00:17:48.250
infrared instruments on the Anglo Australian

429
00:17:48.250 --> 00:17:51.010
telescope. When it was being delivered.

430
00:17:51.310 --> 00:17:53.730
Uh, I think,

431
00:17:54.030 --> 00:17:56.450
um, the detector came under armed guard

432
00:17:56.450 --> 00:17:58.810
almost. It wasn't quite like that. But there

433
00:17:58.810 --> 00:18:01.170
was a lot of hoops to jump through when this

434
00:18:01.170 --> 00:18:03.890
detector was delivered. Because it had to be

435
00:18:03.970 --> 00:18:06.850
certain not to stray into the hands

436
00:18:06.850 --> 00:18:09.210
of certain foreign nations who the

437
00:18:09.370 --> 00:18:12.250
Americans who developed this detector didn't

438
00:18:12.250 --> 00:18:15.050
want, uh, them to get hold of.

439
00:18:15.370 --> 00:18:17.930
So those technologies do eventually

440
00:18:19.050 --> 00:18:21.250
kind of sprinkle down to astronomy where the

441
00:18:21.250 --> 00:18:24.010
poor relations in that regard, uh, although

442
00:18:24.010 --> 00:18:25.930
we do push the limits perhaps more than

443
00:18:25.930 --> 00:18:28.250
anybody else, uh, in technology.

444
00:18:29.210 --> 00:18:31.210
So, um, yes,

445
00:18:31.850 --> 00:18:34.020
I, I don't have any

446
00:18:35.300 --> 00:18:38.030
definite, um, speculations, uh,

447
00:18:38.030 --> 00:18:40.540
except to say that nothing would

448
00:18:40.540 --> 00:18:42.580
surprise me in that regard

449
00:18:43.380 --> 00:18:44.180
when it comes.

450
00:18:45.220 --> 00:18:47.940
Andrew Dunkley: I'm not a conspiracy theorist, but I do

451
00:18:47.940 --> 00:18:50.340
believe there's a heck of a lot going on up

452
00:18:50.340 --> 00:18:53.260
there that we do not and probably will

453
00:18:53.260 --> 00:18:56.260
not know about. Um, and

454
00:18:56.500 --> 00:18:59.290
I truly believe that the technology

455
00:18:59.930 --> 00:19:02.810
available today in space and on

456
00:19:02.810 --> 00:19:05.450
the planet, um, in those

457
00:19:05.530 --> 00:19:08.410
dark corners of government buildings

458
00:19:08.490 --> 00:19:10.730
is far, far more advanced than we

459
00:19:11.450 --> 00:19:14.049
could possibly imagine. I think given what

460
00:19:14.049 --> 00:19:16.730
we've got access to in a domestic sense in

461
00:19:16.730 --> 00:19:18.570
the public arena today,

462
00:19:19.650 --> 00:19:22.290
uh, what's been developed already behind

463
00:19:22.290 --> 00:19:25.170
closed doors that we're unaware of. And

464
00:19:25.170 --> 00:19:27.560
it's probably up. They're circling the planet

465
00:19:27.560 --> 00:19:28.280
as we speak.

466
00:19:29.080 --> 00:19:31.800
Professor Fred Watson: Yeah, I think it works both ways though,

467
00:19:31.800 --> 00:19:34.520
because I think, um, we're now

468
00:19:34.520 --> 00:19:37.320
seeing, uh, the military adopting

469
00:19:37.880 --> 00:19:39.880
what would have been thought of as commercial

470
00:19:39.880 --> 00:19:41.940
products before. Uh,

471
00:19:42.680 --> 00:19:45.240
and that's happened certainly in Ukraine.

472
00:19:45.400 --> 00:19:48.280
There's been an adaptation of

473
00:19:48.440 --> 00:19:51.160
all sorts of commercial products for

474
00:19:51.400 --> 00:19:54.040
military purposes. Um, so

475
00:19:54.120 --> 00:19:55.920
what I guess I'm saying is that the

476
00:19:55.920 --> 00:19:58.780
technology that we use every day is not

477
00:19:58.780 --> 00:20:01.300
as far removed from what the military use

478
00:20:01.700 --> 00:20:04.420
as it would have been 20 or 30 years ago.

479
00:20:05.150 --> 00:20:08.140
Uh, I think that's probably fair to say, but

480
00:20:08.140 --> 00:20:09.940
that's me going out on a limb. And who can

481
00:20:09.940 --> 00:20:10.820
prove me wrong?

482
00:20:11.620 --> 00:20:14.550
Andrew Dunkley: Well, that's a good point too. Yeah, it's a,

483
00:20:14.550 --> 00:20:16.060
uh, really interesting question. Thank you

484
00:20:16.060 --> 00:20:18.700
for sending it in. This is Space Nuts Andrew

485
00:20:18.700 --> 00:20:20.420
Dunkley here with Professor Fred Watson

486
00:20:20.420 --> 00:20:20.980
Watson.

487
00:20:22.900 --> 00:20:25.020
Professor Fred Watson: I believe that this nation should commit

488
00:20:25.020 --> 00:20:27.140
itself to achieving the goal

489
00:20:27.980 --> 00:20:30.940
before this decade is out of landing A man

490
00:20:30.940 --> 00:20:33.020
on the moon and returning him safely

491
00:20:33.020 --> 00:20:34.540
Andrew Dunkley: to the Earth face nuts.

492
00:20:35.660 --> 00:20:38.540
Another audio question from Fred.

493
00:20:39.260 --> 00:20:41.780
Andrew Dunkley: Hi, this is Fred calling you from St. Paul,

494
00:20:41.780 --> 00:20:44.540
Minnesota in the US I have a question for

495
00:20:44.540 --> 00:20:47.420
you regarding the solar systems that contain

496
00:20:48.050 --> 00:20:50.620
uh, so called hot Jupiter planets, those

497
00:20:50.620 --> 00:20:53.180
which are very close, ah, around their

498
00:20:53.180 --> 00:20:55.930
suns. Is it reasonable at all to

499
00:20:55.930 --> 00:20:58.010
expect that they will have

500
00:20:58.570 --> 00:21:00.890
smaller planets, rocky planets,

501
00:21:01.370 --> 00:21:04.370
or are there good reasons that

502
00:21:04.370 --> 00:21:06.130
come to mind where that should not be the

503
00:21:06.130 --> 00:21:08.970
case? Um, I'd uh, appreciate hearing

504
00:21:09.130 --> 00:21:12.130
your theories on this, uh, what the variables

505
00:21:12.130 --> 00:21:14.730
would be in this and I of course enjoy

506
00:21:15.050 --> 00:21:17.930
listening to your show. Thank you very much.

507
00:21:18.330 --> 00:21:19.050
Goodbye.

508
00:21:19.450 --> 00:21:22.010
Andrew Dunkley: Thank you Fred. Uh, Fred's one of our semi

509
00:21:22.010 --> 00:21:24.430
regular sender inners and um,

510
00:21:24.890 --> 00:21:27.350
he's always got a very interesting question

511
00:21:27.350 --> 00:21:30.030
in mind. Um, so uh, yeah, I'm

512
00:21:30.030 --> 00:21:32.390
guessing that what he is asking is if you've

513
00:21:32.390 --> 00:21:35.220
got a solar system with hot Jupiters, uh,

514
00:21:35.220 --> 00:21:38.070
that are orbiting their parent star in

515
00:21:38.070 --> 00:21:41.030
close proximity, could those systems

516
00:21:41.030 --> 00:21:43.550
have rocky planets further out? Now, uh, the

517
00:21:43.550 --> 00:21:45.950
downside of exoplanet detection is rocky

518
00:21:45.950 --> 00:21:47.990
planets are very hard to find at a distance.

519
00:21:47.990 --> 00:21:50.670
You generally find the gas giants

520
00:21:50.670 --> 00:21:53.600
fast or first. Um,

521
00:21:53.910 --> 00:21:55.830
we do know there are a lot of hot Jupiters

522
00:21:55.830 --> 00:21:57.430
out there because we've talked about them.

523
00:21:58.150 --> 00:22:00.130
Um, but uh, yeah,

524
00:22:01.170 --> 00:22:04.010
uh, what's the likelihood that that's a

525
00:22:04.010 --> 00:22:06.970
common thing? Um, not that there's

526
00:22:06.970 --> 00:22:09.930
anything absolutely common about anything you

527
00:22:09.930 --> 00:22:12.210
find when you start looking around at other

528
00:22:12.210 --> 00:22:13.090
solar systems?

529
00:22:13.409 --> 00:22:16.330
Professor Fred Watson: Yeah, that's exactly right. Our solar

530
00:22:16.330 --> 00:22:18.250
system is very neat and tidy compared with

531
00:22:18.250 --> 00:22:20.930
most of the other ones that we've detected.

532
00:22:20.930 --> 00:22:23.530
But you're absolutely right Andrew. Um, the

533
00:22:23.530 --> 00:22:25.830
rocky planets are the, the tricky ones to

534
00:22:25.830 --> 00:22:28.190
observe. And so it might well be that

535
00:22:28.990 --> 00:22:31.030
what we're seeing is effectively a selection

536
00:22:31.030 --> 00:22:33.630
effect. We're selecting the easiest ones,

537
00:22:34.190 --> 00:22:37.070
uh, to discover. Uh, and that's why we see a

538
00:22:37.070 --> 00:22:40.030
lot of hot Jupiters without any evidence

539
00:22:40.030 --> 00:22:42.910
of rocky planets in the same solar systems,

540
00:22:43.870 --> 00:22:46.710
I think, and I haven't looked at this for

541
00:22:46.710 --> 00:22:49.550
some time but um, one of the ideas

542
00:22:49.710 --> 00:22:52.250
for why we've got this

543
00:22:52.250 --> 00:22:55.250
situation with hot Jupiters is basically

544
00:22:56.210 --> 00:22:59.170
a planetary migration. This is where planets

545
00:22:59.170 --> 00:23:01.970
change their positions in the solar system.

546
00:23:02.760 --> 00:23:04.330
Uh, and that might have happened to some

547
00:23:04.330 --> 00:23:07.250
extent in our solar system, but not

548
00:23:07.810 --> 00:23:10.690
in um, a really sort

549
00:23:10.690 --> 00:23:13.570
of existential way. Not in a way that will

550
00:23:13.650 --> 00:23:15.890
totally alter the shape of the solar system

551
00:23:16.130 --> 00:23:17.930
because we've got four rocky planets which

552
00:23:17.930 --> 00:23:20.810
are the innermost ones and they exist within

553
00:23:20.810 --> 00:23:23.320
a zone where um,

554
00:23:23.540 --> 00:23:26.300
water exists as a

555
00:23:26.300 --> 00:23:29.140
gas, whereas beyond the orbit of Mars,

556
00:23:29.220 --> 00:23:31.500
and we sometimes call that the frost line or

557
00:23:31.500 --> 00:23:34.100
the ice line water exists

558
00:23:34.780 --> 00:23:37.619
uh, as ice and that ice is what

559
00:23:37.619 --> 00:23:40.260
has allowed the gas giants to grow

560
00:23:40.820 --> 00:23:43.700
to the size that they have because the ice

561
00:23:43.700 --> 00:23:46.580
basically collects and uh, the

562
00:23:46.660 --> 00:23:48.680
planets absorb it. So you've got ah,

563
00:23:50.100 --> 00:23:52.580
not just a massive rock being formed but ice

564
00:23:52.580 --> 00:23:55.540
as well. And then you end up with a gas

565
00:23:55.540 --> 00:23:58.340
giant planet. Uh so the four gas giants

566
00:23:58.340 --> 00:24:00.300
we think are ah, like that because they're

567
00:24:00.300 --> 00:24:03.220
outside the frost line. Now if you've got

568
00:24:03.220 --> 00:24:05.940
planetary migration taking place then

569
00:24:06.180 --> 00:24:08.620
some of those planets could wander in to the

570
00:24:08.620 --> 00:24:10.740
inner solar system. Uh and

571
00:24:11.700 --> 00:24:14.700
it may essentially leave your solar

572
00:24:14.700 --> 00:24:16.940
system looking like some of the ones that we

573
00:24:16.940 --> 00:24:19.820
see with a hot Jupiter orbiting very close

574
00:24:19.820 --> 00:24:22.160
to Paris star. But also

575
00:24:22.480 --> 00:24:24.720
perhaps with some rocky planets lingering

576
00:24:25.160 --> 00:24:27.760
uh, moaning around or moping around

577
00:24:28.280 --> 00:24:31.200
uh, where they've been uh, projected

578
00:24:31.200 --> 00:24:33.280
to by the rearrangement of the planets

579
00:24:33.600 --> 00:24:35.760
because some of them could be ejected by

580
00:24:35.840 --> 00:24:38.400
planetary migration. If you've got your gas

581
00:24:38.400 --> 00:24:40.680
giant wanders too near your little rocky

582
00:24:40.680 --> 00:24:42.520
planet, it's going to boot it out the solar

583
00:24:42.520 --> 00:24:45.360
system altogether. Uh but um, I

584
00:24:45.360 --> 00:24:47.850
suspect that there will be solar systems uh,

585
00:24:48.340 --> 00:24:50.840
ah that will turn out to have both hot

586
00:24:50.840 --> 00:24:53.020
Jupiters and rocky planets. And as our

587
00:24:54.060 --> 00:24:56.300
um, technology improves and allows us to

588
00:24:56.300 --> 00:24:59.220
detect these things uh, at lower masses, I

589
00:24:59.220 --> 00:25:01.420
think we'll be finding them as well. So um,

590
00:25:01.420 --> 00:25:03.300
watch this space phantom. That's the bottom

591
00:25:03.300 --> 00:25:03.740
line there.

592
00:25:04.220 --> 00:25:06.060
Andrew Dunkley: Theo was a wandering planet.

593
00:25:06.540 --> 00:25:08.540
Professor Fred Watson: Yes, that's right. Theo wandered into the

594
00:25:08.540 --> 00:25:11.420
Earth back in the uh, literally

595
00:25:11.500 --> 00:25:14.380
late 4,000 B.C. yeah,

596
00:25:15.260 --> 00:25:17.540
4,000 million BCS. I beg your pardon. Four

597
00:25:17.540 --> 00:25:18.780
billion. Yeah.

598
00:25:19.570 --> 00:25:22.290
Andrew Dunkley: I think um, the train of thought these days

599
00:25:22.290 --> 00:25:25.170
is that uh, in terms of solar systems,

600
00:25:25.370 --> 00:25:28.370
um, just about every star has at least got

601
00:25:28.370 --> 00:25:31.250
one planet. Um, that's based

602
00:25:31.250 --> 00:25:33.890
on an average assumption. But um,

603
00:25:34.530 --> 00:25:36.790
it also stands to reason that uh,

604
00:25:37.250 --> 00:25:40.250
solar systems are as many and as varied as

605
00:25:40.250 --> 00:25:43.170
there are stars in the sky. Ours

606
00:25:43.490 --> 00:25:45.290
which has the four rocky planets, then the

607
00:25:45.290 --> 00:25:47.890
gas giants as you move out and then the dwarf

608
00:25:47.890 --> 00:25:50.610
planets beyond that um, ours

609
00:25:50.610 --> 00:25:53.330
seems to be quite different

610
00:25:53.330 --> 00:25:54.050
from most.

611
00:25:54.690 --> 00:25:56.930
Professor Fred Watson: It does, that's what I meant. It's very neat

612
00:25:56.930 --> 00:25:59.250
and tidy compared with uh, what we see

613
00:25:59.250 --> 00:26:02.210
elsewhere. Um, certainly

614
00:26:02.610 --> 00:26:05.530
if you were on uh, the planet of

615
00:26:05.530 --> 00:26:08.410
a star 100 light years away, our rocky

616
00:26:08.410 --> 00:26:10.250
planets would be very difficult to detect.

617
00:26:10.250 --> 00:26:12.410
And you just think, you'd probably think all

618
00:26:12.410 --> 00:26:15.410
it had was Jupiter, uh because you'd be

619
00:26:15.410 --> 00:26:17.850
able to detect Jupiter relatively easily. If

620
00:26:17.850 --> 00:26:19.630
it passed in front of the sun it would, would

621
00:26:19.630 --> 00:26:22.470
produce a 1% drop in the um, light

622
00:26:22.470 --> 00:26:25.310
of the sun. And that's easy to

623
00:26:25.310 --> 00:26:28.110
measure. So yes. So um,

624
00:26:28.170 --> 00:26:30.790
uh is the future

625
00:26:31.270 --> 00:26:33.510
of our solar system, one that does involve

626
00:26:33.510 --> 00:26:36.430
planetary migration. Um, it doesn't seem

627
00:26:36.430 --> 00:26:38.310
to be. The planets seem to be in very, very

628
00:26:38.310 --> 00:26:40.870
stable orbits. And maybe that's just

629
00:26:40.870 --> 00:26:42.470
something to do with the geometry of the

630
00:26:42.470 --> 00:26:44.830
solar system itself. But maybe it's something

631
00:26:44.830 --> 00:26:47.630
to do also with why intelligent

632
00:26:47.630 --> 00:26:49.390
life has evolved on one of those planets.

633
00:26:49.390 --> 00:26:51.280
Because we've had this idea long term

634
00:26:51.280 --> 00:26:53.640
stability over many millions of years,

635
00:26:54.520 --> 00:26:54.800
which

636
00:26:54.800 --> 00:26:56.640
Andrew Dunkley: is why it's going to be near impossible to

637
00:26:56.640 --> 00:26:59.240
find another intelligent, communicative

638
00:26:59.400 --> 00:27:02.160
civilization. Because, um, the circumstances

639
00:27:02.160 --> 00:27:03.000
are unique.

640
00:27:03.240 --> 00:27:05.360
Professor Fred Watson: Could be, probably, yeah, could be almost

641
00:27:05.360 --> 00:27:06.800
unique. Yes.

642
00:27:06.800 --> 00:27:07.720
Andrew Dunkley: Thank you, Fred.

643
00:27:10.280 --> 00:27:11.720
Professor Fred Watson: Roger, you're allowed to clear here.

644
00:27:11.720 --> 00:27:14.280
Andrew Dunkley: Also space nuts. Our final question

645
00:27:14.520 --> 00:27:17.040
comes from Ed. Now this is not dissimilar to

646
00:27:17.040 --> 00:27:19.400
a question we had recently, but it's not

647
00:27:19.400 --> 00:27:21.960
quite the same either. Uh, we believe

648
00:27:22.580 --> 00:27:25.060
that nothing can escape from a black hole.

649
00:27:25.060 --> 00:27:27.900
And yet when two black holes merge, the mass

650
00:27:27.900 --> 00:27:30.260
of the surviving black hole is significantly

651
00:27:30.260 --> 00:27:31.980
less than the combined mass of the two

652
00:27:31.980 --> 00:27:34.740
merging black holes. It would appear this

653
00:27:34.740 --> 00:27:36.780
missing mass, which I understand is converted

654
00:27:36.780 --> 00:27:39.580
to gravitational waves, has to come from the

655
00:27:39.580 --> 00:27:42.300
black holes, hence energy. Matter does

656
00:27:42.300 --> 00:27:44.820
escape from black holes. Is this

657
00:27:44.980 --> 00:27:47.740
wrong? Ed asks. Hello, Ed, thanks for the

658
00:27:47.740 --> 00:27:50.140
question. Uh, black hole questions,

659
00:27:50.140 --> 00:27:52.860
Fred Watson. It's not. A week goes by we

660
00:27:52.860 --> 00:27:54.090
don't get a black hole.

661
00:27:54.240 --> 00:27:56.200
Professor Fred Watson: A great one, though. It's a good question

662
00:27:56.200 --> 00:27:59.200
that Ed's raised. Um, so it's.

663
00:27:59.440 --> 00:28:02.400
Yes, the uh, gravitational radiation

664
00:28:03.200 --> 00:28:03.600
is

665
00:28:06.640 --> 00:28:07.760
quite different from

666
00:28:09.540 --> 00:28:11.920
uh, the electromagnetic radiation that's

667
00:28:12.160 --> 00:28:14.280
coming from a black hole which does get

668
00:28:14.280 --> 00:28:16.480
trapped. It can't pass the event horizon.

669
00:28:16.480 --> 00:28:18.000
That's what the event horizon is all about.

670
00:28:18.800 --> 00:28:21.770
Because gravitation is a property

671
00:28:22.250 --> 00:28:25.250
not of the black hole, but of

672
00:28:25.250 --> 00:28:28.210
the universe itself. Ah. It's

673
00:28:28.210 --> 00:28:30.970
the underlying sort of fabric of space that

674
00:28:30.970 --> 00:28:33.770
is what carries gravity. Um,

675
00:28:33.930 --> 00:28:36.890
and so if you've got these colliding

676
00:28:36.890 --> 00:28:39.130
black holes, they shake the space

677
00:28:39.930 --> 00:28:42.570
itself rather than emit

678
00:28:43.130 --> 00:28:45.730
something. So that's the

679
00:28:45.730 --> 00:28:48.440
difference. The gravitational waves. Uh,

680
00:28:48.570 --> 00:28:51.450
yes, indeed. They're caused by, uh, the,

681
00:28:51.750 --> 00:28:54.270
by a loss of mass from the black holes. But

682
00:28:54.270 --> 00:28:56.790
they're not a property of the black holes. If

683
00:28:56.790 --> 00:28:59.790
I can put it that way. Yes, it's an

684
00:28:59.790 --> 00:29:02.070
effect rather than something being emitted.

685
00:29:02.390 --> 00:29:05.350
So, um, um, Ed's quite right that

686
00:29:05.350 --> 00:29:07.709
nothing can escape a black hole, but

687
00:29:07.709 --> 00:29:10.590
gravitational waves apparently do. But

688
00:29:10.590 --> 00:29:13.030
they're not. Basically what you're seeing is,

689
00:29:13.670 --> 00:29:15.870
uh, something to do with the universe, not

690
00:29:15.870 --> 00:29:16.630
the black hole.

691
00:29:17.910 --> 00:29:20.110
Andrew Dunkley: Okay, yeah, I get it. It's the old pebble in

692
00:29:20.110 --> 00:29:21.150
the pond trick.

693
00:29:21.150 --> 00:29:23.350
Professor Fred Watson: Yeah, that's right. Yes it is, yeah.

694
00:29:24.390 --> 00:29:27.230
The ripples in the pond, uh, don't come

695
00:29:27.230 --> 00:29:30.230
from the pebble. They come from the fact that

696
00:29:30.230 --> 00:29:32.710
the pebble has disturbed the underlying

697
00:29:33.269 --> 00:29:35.390
fabric. Uh, of the water, in fact. Put it

698
00:29:35.390 --> 00:29:37.750
that way. Yeah, it's a really good analogy.

699
00:29:39.750 --> 00:29:41.030
Andrew Dunkley: I come up with all sorts.

700
00:29:41.190 --> 00:29:43.310
Professor Fred Watson: You do, but that's a cracking good one,

701
00:29:43.310 --> 00:29:44.550
Andrew. Well done. I like that.

702
00:29:45.030 --> 00:29:46.870
Andrew Dunkley: I think you told it to me once before.

703
00:29:48.960 --> 00:29:49.280
Maybe.

704
00:29:49.440 --> 00:29:49.930
Professor Fred Watson: Maybe.

705
00:29:49.930 --> 00:29:52.160
Andrew Dunkley: Um, so that's the simplicity of it, really.

706
00:29:52.160 --> 00:29:53.680
There's not much more to tell.

707
00:29:53.680 --> 00:29:55.520
Professor Fred Watson: No, no, that's right. It's not. You know, it

708
00:29:55.520 --> 00:29:58.040
doesn't defy the logic of nothing being able

709
00:29:58.040 --> 00:30:01.030
to escape a black hole. Uh, it's, um,

710
00:30:01.440 --> 00:30:04.200
because you, um. Yes, Ed's right. Nothing

711
00:30:04.200 --> 00:30:06.480
can. Nothing solid or,

712
00:30:07.030 --> 00:30:09.840
um, electromagnetic or particles

713
00:30:09.840 --> 00:30:12.560
can't either. Uh, but the

714
00:30:12.560 --> 00:30:15.080
gravitational field is different. It's

715
00:30:15.080 --> 00:30:17.360
something to do with the underlying universe.

716
00:30:18.410 --> 00:30:20.570
Andrew Dunkley: Indeed it is. Uh, thanks, Ed. Great question.

717
00:30:21.210 --> 00:30:24.170
And, um, yeah, answered

718
00:30:24.250 --> 00:30:26.810
very simply in the end. Which

719
00:30:27.050 --> 00:30:28.570
doesn't happen often, does it, really?

720
00:30:29.130 --> 00:30:30.970
Professor Fred Watson: No, usually they're not answered at all.

721
00:30:32.410 --> 00:30:33.690
Andrew Dunkley: Or just adequately.

722
00:30:33.690 --> 00:30:36.010
Professor Fred Watson: Yes, adequately. That's right.

723
00:30:36.090 --> 00:30:38.010
Andrew Dunkley: Thanks, Ed. Uh, thanks to everyone who's sent

724
00:30:38.010 --> 00:30:39.810
in questions. And if you would like to send a

725
00:30:39.810 --> 00:30:41.970
question to us, please do go to our website,

726
00:30:41.970 --> 00:30:44.730
spacenutspodcast.com or spacenuts

727
00:30:44.810 --> 00:30:47.170
IO and there's a little button, uh, up the

728
00:30:47.170 --> 00:30:49.930
top top. Uh, or a tab or a link or whatever.

729
00:30:49.930 --> 00:30:52.650
It's a link. Uh, AMA stands for Ask me

730
00:30:52.650 --> 00:30:54.570
Anything. And you can send your questions in

731
00:30:54.570 --> 00:30:56.850
through that particular interface,

732
00:30:57.570 --> 00:31:00.210
text or audio. Don't forget to tell us who

733
00:31:00.210 --> 00:31:01.570
you are or where you're from. Although

734
00:31:01.570 --> 00:31:03.650
sometimes people forget. And you're not going

735
00:31:03.650 --> 00:31:06.090
to get into trouble for that. We're not that

736
00:31:06.090 --> 00:31:07.840
kind of people. M

737
00:31:08.290 --> 00:31:10.650
Nobody there. Have a look around. Visit the

738
00:31:10.650 --> 00:31:13.090
shop, become a supporter. And don't forget to

739
00:31:13.330 --> 00:31:15.490
leave, uh, reviews wherever you listen to us.

740
00:31:15.730 --> 00:31:18.680
Maybe the people listening live right now

741
00:31:18.680 --> 00:31:20.760
via YouTube could leave reviews. That'd be

742
00:31:20.760 --> 00:31:23.120
nice. Unless they hated us. Just don't do

743
00:31:23.120 --> 00:31:26.000
anything. No, I'm just kidding. They've stuck

744
00:31:26.000 --> 00:31:27.680
around, so we must be doing something right.

745
00:31:28.160 --> 00:31:28.720
Professor Fred Watson: Yeah.

746
00:31:28.880 --> 00:31:30.360
Andrew Dunkley: And we're all done, Fred Watson. Thank you

747
00:31:30.360 --> 00:31:30.880
very much.

748
00:31:31.440 --> 00:31:34.280
Professor Fred Watson: Thank you, Andrew. Um, we'll talk again soon.

749
00:31:34.280 --> 00:31:35.520
I, uh, look forward to it.

750
00:31:35.840 --> 00:31:37.880
Andrew Dunkley: I hope so. Uh, Professor Fred Watson Watson,

751
00:31:37.880 --> 00:31:39.640
astronomer at large, thanks to Huw in the

752
00:31:39.640 --> 00:31:42.640
studio, um, who couldn't be with

753
00:31:42.640 --> 00:31:45.440
us today because, uh, he's got a black

754
00:31:45.440 --> 00:31:48.120
hole problem. He called a plumber and neither

755
00:31:48.120 --> 00:31:50.500
of them can get out. And from me, Andrew

756
00:31:50.500 --> 00:31:52.780
Dunkley. Thanks for your company. I'll catch

757
00:31:52.780 --> 00:31:55.380
you on the next episode of Space Nuts. Until

758
00:31:55.380 --> 00:31:58.220
then, bye bye. You've been

759
00:31:58.220 --> 00:32:00.460
listening to the Space Nuts podcast

760
00:32:01.980 --> 00:32:04.700
available at Apple Podcasts, Spotify,

761
00:32:05.020 --> 00:32:07.700
iHeartRadio or your favourite podcast

762
00:32:07.700 --> 00:32:09.460
player. You can also stream on

763
00:32:09.460 --> 00:32:11.310
demand@bytes.com um,

764
00:32:11.500 --> 00:32:13.540
Professor Fred Watson: this has been another quality podcast

765
00:32:13.540 --> 00:32:15.660
production from bytes.um com.