Stellar Q&A: Rusty Moons, Space Stations & What If Earth Disappeared? | Space Nuts: Astronomy...

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Language: en

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Hi there. Thanks for joining us. This is


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a Q&A edition of Space Nuts. Not only do


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we talk astronomy and space science, we


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pretend to answer questions from our uh


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wonderful audience. We've got a bunch


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today. Uh Bill is asking about small


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bodies in solar systems. I don't think


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that's got anything to do with weight


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loss, but we'll see. Uh Peter is asking


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about leaving something behind that


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could survive the destruction of Earth.


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Wow, that's a what if question. Tiny


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moons and giant planets and issues with


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a giant space station. Those are


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questions we will endeavor to answer


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today on this edition of Space Nuts.


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>> 15 seconds. Guidance is internal. 10 9g


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Ignition sequence start.


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>> Space nuts.


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>> 5 4 3 2 1 2 3 4 5 5 4 3 2 1.


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>> Space nuts.


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>> Astronauts report. It feels good.


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And with us again is Professor Fred


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Watson, astronomer at large. Hello,


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Fred.


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>> Hello, Andrew. Uh, fancy seeing you


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here.


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>> Yes. Unusual. We're both wearing black.


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>> Is it black?


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>> Uh, it is. Yeah.


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>> It's the um this is the the shirt that


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if I have Jordi sitting on my lap, you


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you can't see him at all cuz it's


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exactly the same color as he is. Jet


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black. Uh, that'll make a good Instagram


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photo.


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>> Well, it might do. Yes.


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>> Just two eyes poking out.


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>> Now, um, we got a lot to get through, so


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we'll start straight away with, uh, a


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question that comes from Bill, and he


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asks, "If small bodies in the solar


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system formed by accretion of fine dust


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and gas, why are they not all fluffy,


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low gravity powder puffs? Um,


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we're all dense stony uh or uh were all


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dense stony or metallic objects


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originally part of a larger body that


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could differentiate under uh decent


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gravity levels then were smashed to


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small pieces in collisions. Uh thanks


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for the great podcast uh that comes from


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Bill. Um so yeah, why isn't everything


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puffy?


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>> Um I think it was to start with. Uh well


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so yeah so we you know um people often


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say


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people who should know better often say


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that if you want to know how planet


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formation starts look under your bed


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because the bits of the bits of fluff


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that you tend to find under your bed are


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made of dust sticking together uh


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usually by electrostatic forces which we


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think played a part in in the early


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evolution of planets. uh these things


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stick together, you build up bigger and


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bigger fluff balls. Um and eventually


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the fluff balls because as exactly as um


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as Bill says, they do tend to collide


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with one another. We're now talking


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about a very very densely a very very


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dense dusty environment. We're talking


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about the protolanetary disc that


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surrounded the sun. uh very dusty place


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with lots of um basically lots of


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capacity for uh dust fluff balls to


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build up to have bigger and bigger


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sizes. Eventually these various forces


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uh will cause the dust balls to sort of


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collapse. Probably collisions will


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contribute to that. Um by that I mean


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that they tend to lose their porosity.


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In other words, they become more solid.


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Um, now having said that, there are


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objects in space that we know are very


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porous. Um, well, we've we've found


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powder puff planets, haven't we?


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>> Yes, that's right. Uh, yes, almost


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exactly a good description of them. I'm


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just thinking more nearer to home,


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though. Um uh uh Phobos, the larger moon


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of Mars, is thought to have a


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composition a bit a bit like um God, the


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word's gone. Uh stuff that forms when


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eruptions uh take place under water.


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>> A honeycomb.


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>> Yes. Um but it's got a word. Oh, that's


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ridiculous. When you get to a certain


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age, words just disappear. Um it'll come


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to me in a minute. I know. Uh but yeah,


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the the stuff that floats on on the


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water from an underground eruption.


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Pummus, the very word. That's what I was


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looking for. Thank you. Thank you,


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Andrew. So, pummus is, you know, it's


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porous. It's a it's a a stony structure


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uh that's got a lot of gaps in it. And I


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guess that might well be an intermediate


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structure of many of these objects. As I


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said, Phobos is like that. Uh one of


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Saturn's moons, and I can't remember


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which one it is. It's the one shaped


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like a potato. That'll probably come to


00:04:56.560 --> 00:04:59.590
me in a minute as well. Uh it's also got


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that sort of structure. Um so maybe you


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know when you get things like that


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colliding uh then you and and building


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up in size then you're eventually going


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to get to this situation where gravity


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takes over uh and it pulls um these low


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density materials into something more


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solid. Um


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>> is it a m A malfia. A mouth.


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>> No. Uh, it's one with a better known


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name. It's It's very highly created and


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potato-shaped.


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>> Okay.


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>> Uh, it's uh, yeah, it's one of the most


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created objects in the in the solar


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system. I'm annoyed I can't remember it.


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It's ridiculous.


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>> I was getting too old for this, Andrew.


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>> Oh, no you're not.


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>> No, I know. Maybe I'm not. No. Keeps


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your brain active. Well, except it's


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demonstrating quite clearly uh that the


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memory banks are disappearing. Anyway,


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um it'll come to me as I said in a


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minute. It's not Enceladus, but it's


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something like that. Uh so, uh if you've


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got, you know, gravity taking over, then


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you're likely to get basically solid


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rock emerging from that. Uh as as uh as


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Bill says, dense stony or metallic


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objects, that's basically what they turn


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into. And then they collide. uh uh the


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larger objects are differentiated that


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means the heavy stuff sinks to the


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middle uh exactly as Bill says but they


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collide and that's how you can get stony


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meteorites or metallic meteorites


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because the metal tends to sink mostly


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uh to the middle so I think it's um it


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is a natural process but it's one in a


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way it's counterintuitive to us you know


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how do you get from a dust a fluff ball


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under your bed how do you get from that


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to a to a stone to rock gravity


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>> and yes that's right gravity but over a


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long period of time


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>> uh and probably heat as well you know


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you've got heat processes coming into


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this too


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>> so um uh I think I think uh what um


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Bill's saying is right if the small


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bodies in the solar system formed by


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accretion of fine dust and gas why are


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they not all fluffy lowg gravity powder


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puffs well some of them are and that's


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perhaps you could describe them like uh


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like um Phobos. Perhaps he could


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describe them as unevolved. They haven't


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evolved much. I think it might be


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Hyperion, the one I'm thinking of.


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>> Okay.


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>> Um I think it might be Hyperion.


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>> I'll have a look.


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>> Have a look. See if it's uh shaped like


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a potato and got lots of craters on it.


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>> Yeah. There's got to be a photo of it


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somewhere. Yes, it is.


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>> Yeah. Okay. Good.


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>> It's got It's got that big um


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>> It's got a massive crater in it,


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actually.


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>> Yeah, it does. Yes. Yeah. Yeah. So, um,


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so


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>> you got there in the end, Fred,


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>> in the end. Yeah. It's Yes. It's just


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the processing speed's down a bit. I


00:07:53.520 --> 00:07:55.510
must be offline or something like that.


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Uh,


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>> probably need a reboot.


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>> God, don't say that. I might never come


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back.


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>> Well, that's happened. My car did that


00:08:02.720 --> 00:08:04.150
while we were away.


00:08:04.160 --> 00:08:07.110
>> Came home and came home and to uh to to


00:08:07.120 --> 00:08:08.710
stop falling asleep, we decided we'd go


00:08:08.720 --> 00:08:10.150
and do the groceries straight after


00:08:10.160 --> 00:08:11.350
getting off a long haul flight.


00:08:11.360 --> 00:08:12.869
>> Oh, yes. Yeah.


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And the car wouldn't start.


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>> Yeah, the battery died. So


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>> Oh, the battery died.


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>> Yeah, that's another 315 bucks. Thank


00:08:20.879 --> 00:08:22.309
you very much.


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>> Yes.


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>> Anyway, that's okay.


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>> It happens. It was 4 years. It lasted


00:08:25.840 --> 00:08:26.309
four years.


00:08:26.319 --> 00:08:27.510
>> Oh, that's all right. That's about as


00:08:27.520 --> 00:08:29.189
long as you get from a battery. Yes, it


00:08:29.199 --> 00:08:31.589
>> is indeed. Uh, but thanks, Bill, for the


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question. I think you answered it


00:08:33.120 --> 00:08:35.829
yourself, but um yes. Uh, and although


00:08:35.839 --> 00:08:39.430
if if you're um someone like me um and


00:08:39.440 --> 00:08:41.190
you don't clean under the bed, uh you


00:08:41.200 --> 00:08:42.949
can watch pl you can watch planets


00:08:42.959 --> 00:08:46.230
evolve. That's what's happening.


00:08:46.240 --> 00:08:47.670
>> Yep, you can.


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>> All right. Uh thanks, Bill. Our next


00:08:49.360 --> 00:08:50.870
question


00:08:50.880 --> 00:08:55.110
uh is coming from Peter. Hello, this is


00:08:55.120 --> 00:08:58.230
Peter in Bington Spa


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and I want to know what would it take


00:09:02.080 --> 00:09:04.630
for humans


00:09:04.640 --> 00:09:09.670
to make something that will survive the


00:09:09.680 --> 00:09:12.150
destruction of Earth


00:09:12.160 --> 00:09:15.269
and then potentially be incorporated


00:09:15.279 --> 00:09:17.670
into a new planet when all the bits of


00:09:17.680 --> 00:09:20.070
Earth become a different planet in


00:09:20.080 --> 00:09:24.870
sometime in the future. Is it possible?


00:09:24.880 --> 00:09:26.550
>> Have a good evening.


00:09:26.560 --> 00:09:28.150
>> Thank you, Peter. That's a what if


00:09:28.160 --> 00:09:30.710
question. Uh yeah, I wonder that's


00:09:30.720 --> 00:09:33.350
that's a very it's a longhaul science


00:09:33.360 --> 00:09:35.750
fiction situation. You you you build


00:09:35.760 --> 00:09:37.350
something that will survive the


00:09:37.360 --> 00:09:39.269
destruction of Earth and then somehow


00:09:39.279 --> 00:09:41.590
the planet reconstitutes itself and


00:09:41.600 --> 00:09:43.590
billions of years later there's an


00:09:43.600 --> 00:09:45.670
intelligent race living on the planet


00:09:45.680 --> 00:09:47.509
and they go, "Oh, hello. What's all this


00:09:47.519 --> 00:09:49.030
then?


00:09:49.040 --> 00:09:51.030
>> This is some leftover of humankind."


00:09:51.040 --> 00:09:51.829
Yeah,


00:09:51.839 --> 00:09:52.870
>> whatever they were.


00:09:52.880 --> 00:09:55.350
>> There there was a a TV series that I


00:09:55.360 --> 00:09:56.710
watched many years ago called


00:09:56.720 --> 00:10:00.150
Childhood's End and it was about the


00:10:00.160 --> 00:10:03.190
destruction of Earth and before it


00:10:03.200 --> 00:10:06.790
before it was destroyed uh the humans


00:10:06.800 --> 00:10:09.269
asked the aliens that rescued the


00:10:09.279 --> 00:10:12.310
children basically uh can we can we just


00:10:12.320 --> 00:10:14.150
leave something behind so they know we


00:10:14.160 --> 00:10:17.430
were here. So they left music.


00:10:17.440 --> 00:10:19.990
>> Lovely. I like that. Yes, I like that


00:10:20.000 --> 00:10:20.550
very much.


00:10:20.560 --> 00:10:21.990
>> I just spoiled the whole thing too, by


00:10:22.000 --> 00:10:22.790
the way.


00:10:22.800 --> 00:10:25.990
>> Um I don't think you did really. Uh


00:10:26.000 --> 00:10:28.150
because yes, that's that's a kind of


00:10:28.160 --> 00:10:29.590
concept, isn't it, that you're leaving


00:10:29.600 --> 00:10:33.990
behind. Uh and my mind when I read


00:10:34.000 --> 00:10:35.910
Peter's question or heard Peter's


00:10:35.920 --> 00:10:38.790
question went to


00:10:38.800 --> 00:10:41.269
more concrete things, not necessarily


00:10:41.279 --> 00:10:42.310
made of concrete.


00:10:42.320 --> 00:10:46.630
>> I wasn't about to say that. But the but


00:10:46.640 --> 00:10:48.470
in a sense we've already done it,


00:10:48.480 --> 00:10:53.829
Andrew, because there are five um little


00:10:53.839 --> 00:10:59.190
spacecraft which are absolute um uh


00:10:59.200 --> 00:11:02.150
monuments to humanity leaving the solar


00:11:02.160 --> 00:11:02.630
system.


00:11:02.640 --> 00:11:03.190
>> Yeah.


00:11:03.200 --> 00:11:05.910
>> Um way way beyond the orbit of Earth.


00:11:05.920 --> 00:11:09.990
Voyager one is probably beyond the


00:11:10.000 --> 00:11:12.870
Actually, that's not quite true. Uh I


00:11:12.880 --> 00:11:14.630
was going to say beyond the limits of


00:11:14.640 --> 00:11:16.630
the sun when it turns into a red giant


00:11:16.640 --> 00:11:20.949
star. Um it will it Voyager one will


00:11:20.959 --> 00:11:25.030
probably survive um the red giant phase


00:11:25.040 --> 00:11:28.230
of our sun. Uh which will take place in


00:11:28.240 --> 00:11:29.990
a few billion years. Yeah.


00:11:30.000 --> 00:11:33.190
>> Uh three or four billion years. um it'll


00:11:33.200 --> 00:11:36.069
survive that but might not survive the


00:11:36.079 --> 00:11:37.910
formation of a planetary nebula when


00:11:37.920 --> 00:11:41.670
you've got hot gas coming off the uh


00:11:41.680 --> 00:11:43.509
being puffed off the surface of the red


00:11:43.519 --> 00:11:45.590
giant. It might actually melt in that


00:11:45.600 --> 00:11:47.590
because it's because planetary nebula


00:11:47.600 --> 00:11:50.069
get to be light years in diameter. Uh


00:11:50.079 --> 00:11:52.630
our voyer is only well it's nearly a


00:11:52.640 --> 00:11:55.269
light day away. Um, on the other hand,


00:11:55.279 --> 00:11:57.430
we've got 3 or 4 billion years to play


00:11:57.440 --> 00:11:59.110
with because the sun's not going to do


00:11:59.120 --> 00:12:01.910
anything really nasty uh within that


00:12:01.920 --> 00:12:03.829
time. So, yes, Voyager One will be well


00:12:03.839 --> 00:12:06.550
out of the way. Probably will survive


00:12:06.560 --> 00:12:11.509
the eventual um evolution and final


00:12:11.519 --> 00:12:13.670
uh final evolutionary stages of the sun


00:12:13.680 --> 00:12:15.110
when it actually turns into a white


00:12:15.120 --> 00:12:18.230
dwarf star. Uh so yes, uh those


00:12:18.240 --> 00:12:20.629
spacecraft, Voyager 1, Voyager 2,


00:12:20.639 --> 00:12:23.350
Pioneer 10, Pioneer 11, is that right?


00:12:23.360 --> 00:12:26.470
and New Horizons. They're the five that


00:12:26.480 --> 00:12:28.629
are leaving the solar system which will


00:12:28.639 --> 00:12:30.550
probably outlive humanity.


00:12:30.560 --> 00:12:32.389
>> They probably won't they probably won't


00:12:32.399 --> 00:12:34.629
be the last. And they won't be the last.


00:12:34.639 --> 00:12:39.430
No, I think that's right. Uh but um


00:12:39.440 --> 00:12:43.430
I mean the the idea of um of the earth


00:12:43.440 --> 00:12:46.069
being destroyed


00:12:46.079 --> 00:12:47.829
the kinds of things that might destroy


00:12:47.839 --> 00:12:50.949
the earth are first of all that eventual


00:12:50.959 --> 00:12:53.190
evolution of the sun to a red giant star


00:12:53.200 --> 00:12:54.870
that will almost certainly melt the


00:12:54.880 --> 00:12:55.670
earth


00:12:55.680 --> 00:12:57.430
>> because it'll you know that this the


00:12:57.440 --> 00:13:01.350
sun's um surface put it that way will be


00:13:01.360 --> 00:13:03.990
um a quarter of a mile from the earth


00:13:04.000 --> 00:13:06.230
and we might be on the inside of it uh


00:13:06.240 --> 00:13:08.629
it'll be it could even overtake the


00:13:08.639 --> 00:13:11.829
planet Mars. So so it's hard to imagine


00:13:11.839 --> 00:13:14.629
how you'd rebuild the earth from the


00:13:14.639 --> 00:13:17.190
debris that is really just molecules uh


00:13:17.200 --> 00:13:19.670
because it will have been vaporized. U


00:13:19.680 --> 00:13:22.150
so I think you've uh in in addressing


00:13:22.160 --> 00:13:23.670
this question you've really got to think


00:13:23.680 --> 00:13:26.470
about things that are have left the


00:13:26.480 --> 00:13:29.269
earth and that really basically pushes


00:13:29.279 --> 00:13:31.590
your mind to the to spacecraft. There


00:13:31.600 --> 00:13:34.069
are some spacecraft which are in orbit


00:13:34.079 --> 00:13:37.670
around the sun uh which have you know


00:13:37.680 --> 00:13:40.230
spacecraft that have been sent exploring


00:13:40.240 --> 00:13:42.790
the inner solar system. Mostly these


00:13:42.800 --> 00:13:44.629
days we we try and get rid of them. We


00:13:44.639 --> 00:13:47.430
plunge them uh into either Jupiter or


00:13:47.440 --> 00:13:49.269
Saturn. Jupiter in the case of Galileo,


00:13:49.279 --> 00:13:52.470
Saturn in the case of Cassini. uh those


00:13:52.480 --> 00:13:55.030
uh spacecraft were destroyed purposely


00:13:55.040 --> 00:13:57.670
so that they didn't accidentally land on


00:13:57.680 --> 00:13:59.430
one of the moons of Jupiter or Saturn


00:13:59.440 --> 00:14:01.509
and leave microbes behind. Yeah.


00:14:01.519 --> 00:14:03.590
>> Um so so you're really talking about


00:14:03.600 --> 00:14:05.030
something that's left the solar system


00:14:05.040 --> 00:14:07.990
and that leaves those five spacecraft


00:14:08.000 --> 00:14:09.990
I've mentioned and they definitely will


00:14:10.000 --> 00:14:12.069
outlast humankind.


00:14:12.079 --> 00:14:14.470
Okay, there you have it, Peter. Um so


00:14:14.480 --> 00:14:16.790
we've already done it kind of. Uh, I I


00:14:16.800 --> 00:14:19.269
don't think you could probably build


00:14:19.279 --> 00:14:21.590
some kind of monolith or something that


00:14:21.600 --> 00:14:25.509
would survive the red giant phase of the


00:14:25.519 --> 00:14:28.150
sun and and overwhelm Earth. That would


00:14:28.160 --> 00:14:31.269
all get destroyed. Um, unless you did it


00:14:31.279 --> 00:14:33.509
deep down inside, but I I don't even


00:14:33.519 --> 00:14:36.550
know if you could do that. I I think a


00:14:36.560 --> 00:14:38.069
red giant phase would be pretty


00:14:38.079 --> 00:14:39.910
cataclysmic, wouldn't it?


00:14:39.920 --> 00:14:42.389
>> Yeah. Uh, yes. If your planet's being


00:14:42.399 --> 00:14:43.829
vaporized, your planet's being


00:14:43.839 --> 00:14:46.069
vaporized. includes a whole.


00:14:46.079 --> 00:14:47.189
>> Yeah,


00:14:47.199 --> 00:14:49.670
>> indeed. Thank you, Peter. Great to hear


00:14:49.680 --> 00:14:51.829
from you. Uh, I love what if questions.


00:14:51.839 --> 00:14:53.829
So, um, thanks for serving it up. This


00:14:53.839 --> 00:14:56.310
is Space Nuts with Andrew Dunley and


00:14:56.320 --> 00:14:59.829
Professor Fred Watson.


00:14:59.839 --> 00:15:01.509
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00:15:01.519 --> 00:15:04.310
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00:17:17.520 --> 00:17:20.789
Listen, Tanganity base here. The angle


00:17:20.799 --> 00:17:21.590
has landed.


00:17:21.600 --> 00:17:23.270
>> Space nuts.


00:17:23.280 --> 00:17:25.029
>> Our next question, Fred, comes from


00:17:25.039 --> 00:17:27.669
Martin in Hezwall. Hezwall, is that


00:17:27.679 --> 00:17:28.390
right?


00:17:28.400 --> 00:17:29.669
>> Yes. Hezwall. Yeah.


00:17:29.679 --> 00:17:30.950
>> Where's that? I know. I'm going to guess


00:17:30.960 --> 00:17:32.549
it's the UK somewhere.


00:17:32.559 --> 00:17:35.510
>> It is indeed. It's um uh on the Whirl


00:17:35.520 --> 00:17:37.430
Peninsula. So, if you think of


00:17:37.440 --> 00:17:38.950
Liverpool, you've been to Liverpool.


00:17:38.960 --> 00:17:39.830
>> I have.


00:17:39.840 --> 00:17:42.070
>> And done the Beatles experience. Is that


00:17:42.080 --> 00:17:44.150
right? Yes. Yeah. Well, across the river


00:17:44.160 --> 00:17:46.230
Murzy from Liverpool is the Whirl


00:17:46.240 --> 00:17:49.909
Peninsula and Hezwall is one of the uh


00:17:49.919 --> 00:17:52.150
one of the towns on that. Um I've said


00:17:52.160 --> 00:17:54.470
before and in fact we've had listener


00:17:54.480 --> 00:17:56.630
comments about this. I had a girlfriend


00:17:56.640 --> 00:17:59.029
once who lived on the Whirl Peninsula


00:17:59.039 --> 00:18:00.710
and so I used to be a very regular


00:18:00.720 --> 00:18:02.070
visitor there to a village called


00:18:02.080 --> 00:18:03.669
Barnston which was not that far from


00:18:03.679 --> 00:18:04.390
Hezil.


00:18:04.400 --> 00:18:06.470
>> There you are. All right. It's very


00:18:06.480 --> 00:18:08.150
pretty too. It's a pretty village.


00:18:08.160 --> 00:18:11.590
>> H okay. Um just wanted to know where you


00:18:11.600 --> 00:18:13.350
were Martin. So, thank you for that. Uh,


00:18:13.360 --> 00:18:15.430
I hope uh you'll answer this question.


00:18:15.440 --> 00:18:18.630
According to Wikipedia, there are now


00:18:18.640 --> 00:18:21.990
known to be 292 satellites


00:18:22.000 --> 00:18:24.390
uh with confirmed orbits around Saturn.


00:18:24.400 --> 00:18:26.789
Presumably, many of these moons are very


00:18:26.799 --> 00:18:29.750
small. So, is there a minimum size for


00:18:29.760 --> 00:18:32.630
an object to be called a moon? And is


00:18:32.640 --> 00:18:34.630
there a minimum size for an object to


00:18:34.640 --> 00:18:38.070
maintain a stable orbit around a planet?


00:18:38.080 --> 00:18:40.950
uh as all the giant planets have ring


00:18:40.960 --> 00:18:43.669
systems, would the smaller particles


00:18:43.679 --> 00:18:45.590
just be absorbed into the rings?


00:18:45.600 --> 00:18:48.390
Conversely, I suppose that many objects


00:18:48.400 --> 00:18:50.230
could be knocked out of the rings to


00:18:50.240 --> 00:18:52.070
form independent satellites that may


00:18:52.080 --> 00:18:53.830
become permanently separated from the


00:18:53.840 --> 00:18:57.990
rings. Will Saturn get uh to 1,000 moons


00:18:58.000 --> 00:19:01.029
or more? Also, uh can you recommend a


00:19:01.039 --> 00:19:03.909
website which has the latest data about


00:19:03.919 --> 00:19:06.630
uh the solar system as the numbers vary


00:19:06.640 --> 00:19:09.029
from one site to the next? No doubt due


00:19:09.039 --> 00:19:11.270
to how recent the information is. Keep


00:19:11.280 --> 00:19:14.310
up the good work. Thanks, Martin. That's


00:19:14.320 --> 00:19:16.549
a good question because yeah, we we know


00:19:16.559 --> 00:19:19.909
that the ring systems um are full of


00:19:19.919 --> 00:19:21.590
dust and ice, but they've also got


00:19:21.600 --> 00:19:23.750
larger objects that are referred to


00:19:23.760 --> 00:19:26.710
regularly as moons.


00:19:26.720 --> 00:19:28.390
Um, it's interesting. This was one of


00:19:28.400 --> 00:19:30.870
the exact questions that came up in the


00:19:30.880 --> 00:19:33.510
Q&A night, the science in the pub night


00:19:33.520 --> 00:19:36.230
that we had on Lord How Island uh at the


00:19:36.240 --> 00:19:37.510
Dark Sky Festival.


00:19:37.520 --> 00:19:39.350
>> That was that was Martin. He was he was


00:19:39.360 --> 00:19:40.630
there.


00:19:40.640 --> 00:19:43.029
>> Not No, he probably wasn't. Carry on.


00:19:43.039 --> 00:19:44.950
>> Might have been might be. There was a


00:19:44.960 --> 00:19:45.669
Martin there.


00:19:45.679 --> 00:19:48.950
>> Was Did he have a British accent?


00:19:48.960 --> 00:19:51.669
>> Uh, no. He's he's quite Australian, but


00:19:51.679 --> 00:19:53.510
he's not from not from Haswell. But


00:19:53.520 --> 00:19:56.470
yeah. Uh so but no interesting


00:19:56.480 --> 00:19:58.710
coincidence to get the two and I don't


00:19:58.720 --> 00:20:03.029
think at the moment there is a a


00:20:03.039 --> 00:20:06.710
limiting size to differentiate between a


00:20:06.720 --> 00:20:08.630
ring particle


00:20:08.640 --> 00:20:15.110
and a moon. Um so it's it's a it is a


00:20:15.120 --> 00:20:18.470
great question. Um how do you define a


00:20:18.480 --> 00:20:21.110
moon around a planet which is festoned


00:20:21.120 --> 00:20:23.510
with objects orbiting around it


00:20:23.520 --> 00:20:25.750
>> uh in the form of rings. So we think the


00:20:25.760 --> 00:20:30.149
rings of Saturn are the debris of a


00:20:30.159 --> 00:20:33.430
probably a satellite that came within


00:20:33.440 --> 00:20:37.029
the ro limit of the of the planet. The


00:20:37.039 --> 00:20:40.310
ro limit being the point at which uh a


00:20:40.320 --> 00:20:43.270
solid object can't actually survive


00:20:43.280 --> 00:20:45.750
within that distance. In other words,


00:20:45.760 --> 00:20:49.510
that close to the planet. Um, and so it


00:20:49.520 --> 00:20:53.190
broke up into lots of small particles.


00:20:53.200 --> 00:20:56.870
Probably the biggest ring sized, sorry,


00:20:56.880 --> 00:21:00.230
the biggest ring particles


00:21:00.240 --> 00:21:04.070
are in the region of 10 m


00:21:04.080 --> 00:21:05.830
because the rings themselves are only


00:21:05.840 --> 00:21:07.190
about 100 m thick.


00:21:07.200 --> 00:21:10.789
>> Yeah, it's it's quite staggering.


00:21:10.799 --> 00:21:14.549
Um, and 250,000 kilometers in diameter.


00:21:14.559 --> 00:21:17.909
So it's yes it's quite a contrast. Um a


00:21:17.919 --> 00:21:19.830
sort of blade of material in space is


00:21:19.840 --> 00:21:21.909
the way I've always described it.


00:21:21.919 --> 00:21:23.590
>> Uh


00:21:23.600 --> 00:21:26.310
but some of the smaller satellites of


00:21:26.320 --> 00:21:28.789
Saturn and some of them are actually


00:21:28.799 --> 00:21:31.990
embedded in the ring system. Uh some of


00:21:32.000 --> 00:21:35.590
them are measured in single single digit


00:21:35.600 --> 00:21:38.789
kilometers. So they're not that much


00:21:38.799 --> 00:21:42.789
more than the biggest ring particles.


00:21:42.799 --> 00:21:44.470
And I'm not sure that there is a


00:21:44.480 --> 00:21:47.830
definition between the two. And in a


00:21:47.840 --> 00:21:50.549
sense, you could say that every solid


00:21:50.559 --> 00:21:52.470
object within Saturn's rings is a


00:21:52.480 --> 00:21:54.870
satellite. And so you're then talking


00:21:54.880 --> 00:21:57.430
about millions or maybe even billions of


00:21:57.440 --> 00:22:00.870
of moons of Saturn. Uh it's a great


00:22:00.880 --> 00:22:02.630
question and one that I don't have an


00:22:02.640 --> 00:22:05.110
answer for and I perhaps ought to have


00:22:05.120 --> 00:22:06.630
checked it out in the wake of the


00:22:06.640 --> 00:22:09.110
question that came uh at the at the


00:22:09.120 --> 00:22:11.830
science in the pub science in the bolo


00:22:11.840 --> 00:22:13.750
on Lord. Island the week before last


00:22:13.760 --> 00:22:15.350
when we when we did the Dark Sky


00:22:15.360 --> 00:22:16.470
Festival there.


00:22:16.480 --> 00:22:21.990
>> Yeah. Yeah. I He also asked about


00:22:22.000 --> 00:22:24.630
Yeah. Well, I just did a quick check and


00:22:24.640 --> 00:22:27.990
uh top of the tree is is NASA uh for


00:22:28.000 --> 00:22:31.590
upto-date solar system information.


00:22:31.600 --> 00:22:33.830
>> Uh yeah. Uh but the other ones that you


00:22:33.840 --> 00:22:38.070
could try uh the skylive.com


00:22:38.080 --> 00:22:41.750
uh apparently is very highly rated um


00:22:41.760 --> 00:22:43.669
says it offers comprehensive information


00:22:43.679 --> 00:22:45.270
about the most interesting celestial


00:22:45.280 --> 00:22:47.029
objects and sets tools designed to


00:22:47.039 --> 00:22:49.590
support the exploration etc.


00:22:49.600 --> 00:22:52.310
uh the planets today


00:22:52.320 --> 00:22:55.110
uh is also there and there's a specific


00:22:55.120 --> 00:22:58.390
uh NASA page that you can look up called


00:22:58.400 --> 00:23:01.590
eyes on the solar system um and it


00:23:01.600 --> 00:23:05.830
provides a 3D solarcape if you like.


00:23:05.840 --> 00:23:09.110
>> So there's a few ideas if you want to um


00:23:09.120 --> 00:23:11.830
chase them up Martin but um there'd be


00:23:11.840 --> 00:23:14.149
plenty more out there. There's um just


00:23:14.159 --> 00:23:17.590
to name a few more, Global Solar Atlas,


00:23:17.600 --> 00:23:21.510
um the Noah homepage, the space weather


00:23:21.520 --> 00:23:24.070
prediction homepage, um and and Planet


00:23:24.080 --> 00:23:27.350
Labs, just to name a few. So, um and and


00:23:27.360 --> 00:23:29.430
they're constantly being updated as as


00:23:29.440 --> 00:23:32.230
far as I'm aware as things change or as


00:23:32.240 --> 00:23:34.390
new things come to light. So, might be


00:23:34.400 --> 00:23:36.710
worth chasing all of those up because


00:23:36.720 --> 00:23:38.630
they do seem to be um highly


00:23:38.640 --> 00:23:40.710
credentialed. Fred.


00:23:40.720 --> 00:23:43.590
>> Yeah, I was going to say I I usually go


00:23:43.600 --> 00:23:45.830
to NASA when I want the latest figures


00:23:45.840 --> 00:23:49.990
on this sort of thing. Um, so you've uh


00:23:50.000 --> 00:23:51.990
you've confirmed that and also given a


00:23:52.000 --> 00:23:53.350
few other options as well, which is


00:23:53.360 --> 00:23:53.590
good.


00:23:53.600 --> 00:23:55.190
>> Yep. Plenty to look at. There's lots of


00:23:55.200 --> 00:23:57.029
great sites out there. Just just don't


00:23:57.039 --> 00:24:00.390
go to the ones that start with um words


00:24:00.400 --> 00:24:06.710
starting with F and E.


00:24:06.720 --> 00:24:09.029
Um I was thought you were going to say


00:24:09.039 --> 00:24:11.110
don't go to ones that start with space


00:24:11.120 --> 00:24:14.070
and I've not seen the


00:24:14.080 --> 00:24:17.190
that's that's good advice too. Yeah.


00:24:17.200 --> 00:24:19.430
Okay. Uh thank you Martin. Our final


00:24:19.440 --> 00:24:22.950
question today comes from Finn.


00:24:22.960 --> 00:24:25.190
>> Hello Andrew and Fred. It's Finn from


00:24:25.200 --> 00:24:28.070
Nan in the Adelaide Hills in South


00:24:28.080 --> 00:24:30.230
Australia. And a happy May the 4th to


00:24:30.240 --> 00:24:32.310
you as well. I was watching a


00:24:32.320 --> 00:24:34.149
40-year-old documentary the other day


00:24:34.159 --> 00:24:37.029
about a space station orbiting a planet


00:24:37.039 --> 00:24:40.230
and this space station um if it was to


00:24:40.240 --> 00:24:42.149
orbit the earth, I would like to know


00:24:42.159 --> 00:24:45.110
how that would affect the orbit of our


00:24:45.120 --> 00:24:47.909
moon and maybe the orbit of the earth


00:24:47.919 --> 00:24:50.630
around the sun. This space station being


00:24:50.640 --> 00:24:53.510
150 km diameter with a mass of about 10


00:24:53.520 --> 00:24:57.909
the 15 ton. Um, I I'd like to know and


00:24:57.919 --> 00:24:59.590
if for whatever reason this space


00:24:59.600 --> 00:25:02.470
station happened to destroy our planet,


00:25:02.480 --> 00:25:04.549
how would the rest of the planets in the


00:25:04.559 --> 00:25:06.950
solar system be affected by that


00:25:06.960 --> 00:25:08.710
destruction?


00:25:08.720 --> 00:25:11.669
One last question um to you both is um


00:25:11.679 --> 00:25:14.710
what was the first animal in space?


00:25:14.720 --> 00:25:15.990
>> It was a dog.


00:25:16.000 --> 00:25:18.789
>> Ah, don't think it was that. It was


00:25:18.799 --> 00:25:21.110
actually the cow cuz it jumped over the


00:25:21.120 --> 00:25:23.430
moon. Thank you,


00:25:23.440 --> 00:25:25.190
>> dear. Oh, dear Finn. That that was


00:25:25.200 --> 00:25:27.029
probably one of the worst dad jokes I've


00:25:27.039 --> 00:25:28.950
ever heard.


00:25:28.960 --> 00:25:31.830
>> So, but you know, most welcome on this


00:25:31.840 --> 00:25:35.590
show.


00:25:35.600 --> 00:25:35.830
>> Gosh.


00:25:35.840 --> 00:25:37.350
>> Yeah, it was good. It wasn't wasn't even


00:25:37.360 --> 00:25:38.390
adequate that one, was it?


00:25:38.400 --> 00:25:40.470
>> No, it wasn't. No, we strive for


00:25:40.480 --> 00:25:42.870
adequacy and we didn't even achieve


00:25:42.880 --> 00:25:44.310
that.


00:25:44.320 --> 00:25:46.789
>> Thank you, Finn. Uh so the substance of


00:25:46.799 --> 00:25:49.590
his question was uh you got you got a a


00:25:49.600 --> 00:25:52.310
space station orbiting earth at 150


00:25:52.320 --> 00:25:56.149
kilometers in diameter or whatever. Uh


00:25:56.159 --> 00:25:58.470
what kind of effect could that have on


00:25:58.480 --> 00:26:01.750
the orbit of the moon? And


00:26:01.760 --> 00:26:03.350
yeah we'll get to the next part of the


00:26:03.360 --> 00:26:05.190
question after that. Could it have would


00:26:05.200 --> 00:26:08.149
that have any that's pretty big.


00:26:08.159 --> 00:26:10.310
It's it's bit well the critical thing


00:26:10.320 --> 00:26:14.070
was the mass which um which Finn Hley


00:26:14.080 --> 00:26:18.710
mentioned as being 10^ the 15 tons I


00:26:18.720 --> 00:26:22.870
think is what he said. Uh which is 10 to


00:26:22.880 --> 00:26:27.110
the 18 kg. Um and


00:26:27.120 --> 00:26:30.710
so the bottom line is that's not enough.


00:26:30.720 --> 00:26:33.990
Uh the earth just yeah nah forget it. So


00:26:34.000 --> 00:26:38.870
the earth's uh 6* 10 24 kilograms. So


00:26:38.880 --> 00:26:43.830
it's um what is it? It's uh six orders


00:26:43.840 --> 00:26:47.990
of magnitude bigger in mass than uh than


00:26:48.000 --> 00:26:51.590
this space station. And so the other so


00:26:51.600 --> 00:26:54.470
it it it you know it's it's certainly


00:26:54.480 --> 00:26:56.230
not going to affect the orbit of the


00:26:56.240 --> 00:26:59.750
earth. It might perturb the orbit of the


00:26:59.760 --> 00:27:02.549
moon a bit. Yeah. Uh, one of the


00:27:02.559 --> 00:27:05.590
considerations will be how far away is


00:27:05.600 --> 00:27:10.230
it from the earth and our last question


00:27:10.240 --> 00:27:13.029
actually pointed to an answer to that


00:27:13.039 --> 00:27:15.750
and that is that it would if it's 150


00:27:15.760 --> 00:27:18.549
kilometers in diameter it has to be a


00:27:18.559 --> 00:27:20.870
long way away or else it's within the ro


00:27:20.880 --> 00:27:21.830
limit


00:27:21.840 --> 00:27:24.149
>> of of the earth and it would just break


00:27:24.159 --> 00:27:26.630
up straight away. So I I'm not going to


00:27:26.640 --> 00:27:28.149
guess how far away it has to be, but


00:27:28.159 --> 00:27:29.590
it'll be a long way off the Earth if


00:27:29.600 --> 00:27:33.110
it's 150 kilometers in diameter. Um so


00:27:33.120 --> 00:27:36.630
that again um basically mitigates any


00:27:36.640 --> 00:27:39.029
effects it might have on the orbital


00:27:39.039 --> 00:27:40.390
dynamics of the Earth. It certainly


00:27:40.400 --> 00:27:41.830
wouldn't affect the Earth's orbit around


00:27:41.840 --> 00:27:45.029
the Sun. Might just tweak the moon's


00:27:45.039 --> 00:27:48.230
orbit around the Earth a bit. Uh


00:27:48.240 --> 00:27:50.070
wouldn't cause the demolition of the


00:27:50.080 --> 00:27:53.510
Earth. the orbits of the other planets


00:27:53.520 --> 00:27:56.310
wouldn't even bother to to take any


00:27:56.320 --> 00:27:59.269
notice of it. Uh they they are too


00:27:59.279 --> 00:28:01.909
stable compared with uh you know with a


00:28:01.919 --> 00:28:04.149
a thing of that mass and that far away


00:28:04.159 --> 00:28:06.950
from the earth. So, it's a it's an


00:28:06.960 --> 00:28:10.070
interesting thought uh and one that I


00:28:10.080 --> 00:28:12.630
think um we can say yes, you could have


00:28:12.640 --> 00:28:14.870
a space station 150 kilometers in


00:28:14.880 --> 00:28:18.070
diameter weighing 10^ the 15 tons uh and


00:28:18.080 --> 00:28:20.789
it probably would not affect the status


00:28:20.799 --> 00:28:22.549
quo terribly badly.


00:28:22.559 --> 00:28:24.789
>> Okay, there you go. Uh, and I just did a


00:28:24.799 --> 00:28:26.950
quick check, but um, you know, there's


00:28:26.960 --> 00:28:28.950
not much information about how far space


00:28:28.960 --> 00:28:31.269
stations have to be away to avoid the ro


00:28:31.279 --> 00:28:34.549
limit, but a solid object such as a as a


00:28:34.559 --> 00:28:38.630
a rocky body with 150 km diameter would


00:28:38.640 --> 00:28:41.909
have to be at least 141,000 kilometers


00:28:41.919 --> 00:28:43.909
away from Earth.


00:28:43.919 --> 00:28:45.909
>> Probably better off being over 200,000


00:28:45.919 --> 00:28:46.710
kilometers away.


00:28:46.720 --> 00:28:48.549
>> Yes, that that's the sort of distance I


00:28:48.559 --> 00:28:51.269
had in mind. Something like that. three


00:28:51.279 --> 00:28:53.430
times as far away as the um


00:28:53.440 --> 00:28:55.350
geostationary satellites are. There you


00:28:55.360 --> 00:28:58.070
are. Now, he had a second question as to


00:28:58.080 --> 00:28:59.830
what would happen to the other planets


00:28:59.840 --> 00:29:01.990
if Earth was destroyed, no longer


00:29:02.000 --> 00:29:03.750
existed. I think we've been down this


00:29:03.760 --> 00:29:05.430
road before and I can't remember the


00:29:05.440 --> 00:29:06.470
answer.


00:29:06.480 --> 00:29:09.750
>> Yeah. So, um the other planets would


00:29:09.760 --> 00:29:12.710
more or less stay in the present orbits


00:29:12.720 --> 00:29:15.990
there. Those orbits would be perturbed


00:29:16.000 --> 00:29:17.590
uh differently from what they are now.


00:29:17.600 --> 00:29:19.430
So perturbations are the the


00:29:19.440 --> 00:29:21.350
gravitational effects of other bodies in


00:29:21.360 --> 00:29:24.710
the solar system. Uh on the when you


00:29:24.720 --> 00:29:26.310
when you look at the way things are in


00:29:26.320 --> 00:29:27.990
orbit, you start off with a two-body


00:29:28.000 --> 00:29:30.630
problem with the sun and your object in


00:29:30.640 --> 00:29:33.830
orbit. But then you modify it by have it


00:29:33.840 --> 00:29:35.510
taking into account the gravitational


00:29:35.520 --> 00:29:36.950
attraction of other bodies and it


00:29:36.960 --> 00:29:38.389
becomes a three-body problem and then


00:29:38.399 --> 00:29:39.750
four body problem and all the rest of


00:29:39.760 --> 00:29:39.990
it.


00:29:40.000 --> 00:29:40.470
>> Yeah.


00:29:40.480 --> 00:29:43.590
>> Uh now it that three-body problem would


00:29:43.600 --> 00:29:46.470
change if the earth wasn't there. um or


00:29:46.480 --> 00:29:48.149
the endbody problem. I suppose it would


00:29:48.159 --> 00:29:49.990
be a solar system with seven planets


00:29:50.000 --> 00:29:51.190
rather than eight.


00:29:51.200 --> 00:29:53.350
>> Uh that would change the dynamics of the


00:29:53.360 --> 00:29:55.990
planets a little bit. Uh but they would


00:29:56.000 --> 00:29:58.389
basically remain in their present orbits


00:29:58.399 --> 00:30:01.110
uh with with just changes to the orbit


00:30:01.120 --> 00:30:03.029
rather than the orbits being destroyed.


00:30:03.039 --> 00:30:05.190
>> So in other words, if Earth disappeared,


00:30:05.200 --> 00:30:06.710
no great loss.


00:30:06.720 --> 00:30:09.190
>> No, not really. I mean, you know,


00:30:09.200 --> 00:30:11.029
Douglas Adams had it in one. Mostly


00:30:11.039 --> 00:30:11.430
harmless.


00:30:11.440 --> 00:30:13.029
>> Mostly harmless. Yes,


00:30:13.039 --> 00:30:15.669
>> that's right. Thanks for the white mice.


00:30:15.679 --> 00:30:18.149
>> Yes, that's right.


00:30:18.159 --> 00:30:19.750
>> I wonder how all the other mice felt


00:30:19.760 --> 00:30:21.669
about that.


00:30:21.679 --> 00:30:23.909
You know, it was it was mus musculus


00:30:23.919 --> 00:30:25.350
racism. That's what it was.


00:30:25.360 --> 00:30:27.990
>> There it is. Yes. Mass racism. Exactly.


00:30:28.000 --> 00:30:29.029
So,


00:30:29.039 --> 00:30:31.750
>> yeah. Uh, thanks Finn. Great question.


00:30:31.760 --> 00:30:33.909
We We always love these whatifs. So, um,


00:30:33.919 --> 00:30:35.430
if you'd like to keep sending in


00:30:35.440 --> 00:30:36.789
questions like that, or if you got


00:30:36.799 --> 00:30:39.190
something deadly serious to discuss with


00:30:39.200 --> 00:30:41.830
us, like, I don't know, exploding


00:30:41.840 --> 00:30:44.149
rockets and whatever else, uh, you can


00:30:44.159 --> 00:30:46.070
send them into us. Uh, just go to


00:30:46.080 --> 00:30:47.669
spaceenuts.io


00:30:47.679 --> 00:30:49.909
or spacenutspodcast.com,


00:30:49.919 --> 00:30:53.029
click on the ask me anything button. You


00:30:53.039 --> 00:30:54.950
won't be asking me, you'll be asking


00:30:54.960 --> 00:30:57.669
him, but uh, I'll read it out. Or you


00:30:57.679 --> 00:30:59.110
can send us an audio question. As long


00:30:59.120 --> 00:31:00.149
as you've got a device with a


00:31:00.159 --> 00:31:01.830
microphone, you're all set. Uh, and


00:31:01.840 --> 00:31:03.590
while you're there, have a look around.


00:31:03.600 --> 00:31:05.269
Uh, that brings us to the end. Fred,


00:31:05.279 --> 00:31:06.710
thank you very much.


00:31:06.720 --> 00:31:08.789
>> Great pleasure, Andrew. Always good to


00:31:08.799 --> 00:31:10.870
chew the fat and I hope we'll do it


00:31:10.880 --> 00:31:11.430
again soon.


00:31:11.440 --> 00:31:13.269
>> We will. That's Professor Fred Watson,


00:31:13.279 --> 00:31:14.710
astronomer at large, part of the team


00:31:14.720 --> 00:31:16.470
here at Space Nuts. And thanks to Hugh


00:31:16.480 --> 00:31:18.310
in the studio, uh, who couldn't be with


00:31:18.320 --> 00:31:20.070
us today. He was seeing his dietician


00:31:20.080 --> 00:31:24.470
after he reached 10 to the 15 tons.


00:31:24.480 --> 00:31:26.870
I'm surprised he survived. And from me,


00:31:26.880 --> 00:31:28.710
Andrew Dunley, thanks for your company.


00:31:28.720 --> 00:31:30.789
We'll be back again soon with another


00:31:30.799 --> 00:31:32.950
episode of Space Nuts. See you then.


00:31:32.960 --> 00:31:33.909
Bye-bye.


00:31:33.919 --> 00:31:34.870
>> Space Nuts.


00:31:34.880 --> 00:31:36.950
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00:31:39.279 --> 00:31:42.230
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