Cosmic Queries: Understanding Black Holes, Galactic Centres, and Mars Days | Space Nuts:...

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Kind: captions
Language: en

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Hello again and thank you for joining us


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on another episode of Space Nuts. This


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is a Q&A edition where we take audience


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questions, we put them on paper, and


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then we put them on a roll that goes on


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a little thing in a bathroom.


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Or we could answer them. We can do that.


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Uh coming up today, we have uh questions


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uh from John about Martian days. The


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length of a Martian day. It's close, but


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is it close enough to Earth's standard?


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We'll discuss that. Uh, the growth of a


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black hole has been uh brought up again.


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Uh, we've got a um a uh question from an


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11-year-old named Thomas. Hi, Thomas. He


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wants to talk about the galactic center.


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And Paul is asking our uh about our


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galactic location. So, we'll deal with


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all of that today on this episode of


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Space Nuts.


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>> 15 seconds. Guidance is internal. 10 9


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ignition sequence start. Space Nuts.


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>> 5 4 3 2


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>> 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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>> Joining us again to sort all of that out


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is Professor Fred Watson, astronomer at


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large. Hello, Fred.


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>> Hello, Andrew. Good to see you again.


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>> Good to see you, too.


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>> Yes. Despite the hole in my head.


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>> Yeah. Yeah. It doesn't look any better


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than the last time I show you.


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>> It doesn't, does it?


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>> No. I mean, you know, it's only been


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minutes. You'd think it would have


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improved by now.


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>> That's what happens when you walk into a


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when you walk into a closed screen door.


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>> Yeah.


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>> In the dark,


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>> it hurts.


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>> Now, that's why they have stuff um on on


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glass sliding doors. You know, that


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that's a standard safety standard


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required these days so that you know the


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door is there.


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>> Yeah.


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But when it's nighttime and it's a


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screen door, not not many excuses left


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there, Fred. Really?


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>> Only stupidity, I think, is the is the


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last one. But that's that's my excuse


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many, many times.


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>> Yeah. Well, like I said before, we've


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all done it.


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>> Uh shall we try and answer these


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questions?


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>> We should.


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>> Okay, let's go to question one. This one


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comes from John. Uh we know that the


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Martian day is 39 minutes longer than an


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Earth Day. That's about 4 and 1/2 hours


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a week. Uh when and if Mars is populated


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with humans, how would we work with the


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longer day/week?


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Would human biology tend to keep to the


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24-hour day or would we adapt to a


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longer dayight cycle? Thanks. Love the


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show and have been a listener since you


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started. Wow, you've got a lot of spare


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time, John. Uh thank you so much uh for


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sending your question in and hope all is


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well. Uh I love this question because it


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you've got a planet that is close enough


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for us to get to in the not too distant


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future. Probably


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not a permanent settlement, but a


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rotating settlement of some kind will be


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the initial stages of humans being on


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Mars.


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and yet you've got an extra 39 minutes a


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day to deal with. What is going to be


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the impact?


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>> Um I think we've already


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>> have um a lot of data on this because


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the


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>> we've already talked about this once


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before in the dead dark past came up


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again. Yeah.


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>> Yeah. because of the the um um rover


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drivers.


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>> Uh they um people the people who are uh


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in command of if I can put it that way


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because they don't actually drive them


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directly but in command of the the


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rovers on Mars and the two active NASA


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ones at the moment are Curiosity and


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Perseverance.


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uh they adapt to a 20 to 24 hours 39


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minutes day uh and do it quite


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successfully as far as I've been able to


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work out.


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>> Well, I hope so.


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>> Yeah. Otherwise, there might be a pile


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up on Mars. Um, and in fact, the reason


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why I said they don't actually drive


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them is because the the rovers


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themselves have got to be to some extent


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autonomous because of the the the delay


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in in signal time to get between Mars


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and the Earth. You can't have video


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coming back from your rover and a


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steering wheel so that you respond to


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that because you'd have a sort of 20 or


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30 minute delay probably before


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>> uh before um you you turn before the


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wheels turned on on the rover.


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>> I would I would imagine that the the


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manual driving of a rover from Earth on


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Mars would be damn near impossible


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because even your images would be out of


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sync with


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>> everything's out of sync. That's right.


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So you see, oh, there's a rock coming


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up. That was 40 minutes ago.


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>> I'll turn left now.


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>> Oops.


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>> Yeah. Um so so the the rovers drive


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themselves basically uh with a lot of um


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assistance and monitoring from Earth uh


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in order to see what's coming up and see


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what the onboard computers are doing in


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terms of what route they're taking


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through the rocks and debris on Mars.


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uh and um so but those people as I


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understand it do go on to uh this 24


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hours and 39 minutes day length uh I


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think it's near enough to our 24 hours


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that I think they adapt quite quickly


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from my recollection of our previous


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conversation about this Andrew


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>> yeah I if I remember rightly we were


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talking about the fact that if you're


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going to stay on Mars long term you


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would have to adapt


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um you wouldn't adapt naturally


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at all. You you'd have to take catnaps


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or something like that to to catch up um


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or something to that effect.


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>> Well, it Yes. So, your circadian rhythms


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would they'd be under stress. They


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they'd change.


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>> Um um and I suppose you'd have a


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permanent feeling of jet lag probably.


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Probably what it feels like.


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>> It would be tough. I read an article uh


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last weekend which I I found fascinating


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and it was um detailing how the 8hour


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night cycle that humans have like going


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to bed for 8 hours is a myth.


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>> Yes.


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>> And that um it was it was actually


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something invented by a mattress company


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back in 1938. Have you heard this?


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>> No. Yes.


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>> I I I do know that we used to sleep


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twice in the night with it.


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>> That's right. So, you go to bed at like


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9:00


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>> and you'd sleep for 4 hours and then


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you'd get up for 2 hours and you'd do


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stuff


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>> like stuff we can't talk about on this


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podcast, but other stuff like um


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>> they cited a couple of um famous people


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um whose names have dropped straight out


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of my head. Um, William Shakespeare


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>> uh apparently wrote a lot of his famous


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works between 1 and 3 in the morning


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when he got up and then he go back to


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bed for 4 hours. And Bethovven did the


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same thing with some of his symphonies.


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He wrote some of the best works that he


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ever created at 3:00 in the morning um


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during his wake time between his two


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sleeps. Yeah. So the 8hour sleep


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that we have at night was an invention


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apparently to sell mattresses.


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That's what I'm told. I look I haven't


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confirmed or denied that but it seems it


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seems possible I suppose. Well, yes. I I


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think I think we have we've I think um


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there's been evidence from, you know,


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the earliest times,


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uh the times when people truly were


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ancient peoples back thousands of years


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ago, uh that that's how they lived their


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lives, exactly as you've said. And maybe


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there were the last vestigages of that


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were


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>> keeping going in Shakespeare's time and


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then in Beethoven's time. Um


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there weren't that many clocks around


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then. There were some, but not that


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many. It wasn't like you had a


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smartwatch by your bedside or anything


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like that. So, uh it would be a natural


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rhythm that they would use uh to, you


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know, to to sleep and wake up.


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>> Yes. And if you're natural,


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modernization certainly messed us up,


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hasn't it?


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>> Yeah. Yeah, that's right. I think in


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that case it has.


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>> And I think uh on Mars it will be um it


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will be a pretty difficult thing. I I


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imagine


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>> it may be. So, um maybe I can just


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sidestep here slightly, Andrew, because


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um I would very much like to know uh


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what answer one of our listeners would


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give to that. And that's Dr. Heidi


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Deblock, who's I think based in Houston,


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if I remember rightly, who is a


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basically a space medic. Uh and um it


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will be very interesting to hear her


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take on how humans will adapt to that.


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And if I may, she was in touch with us


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recently to comment on one of our


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earlier questions. Would it be all right


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if I read that?


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>> And that was when we were talking about


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how people deal with um gravity when


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they get back on Earth after being out


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in space for a while.


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>> Correct. Yes, that's right.


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>> Uh she says, um, "I just finished the


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July 5th Space Nuts and wanted to help


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answer the question about how the


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astronauts feel when they land back on


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Earth. Of course, I haven't experienced


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it in person, but have worked with


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plenty of astronauts at landing in


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particular. All of our physiology


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changes in space as we are designed for


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1G. Some astronauts are pretty good when


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they land, especially those who are on


00:09:58.640 --> 00:10:01.269
the shuttle and in space for short time


00:10:01.279 --> 00:10:04.550
for a sorry a 4A short time. Some had


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significant problems. They stem from the


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orthostatic hypotension as a result from


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the cardiovascular changes. Some of the


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changes in the inner ear with balance


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and knowing where you physically are,


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some mild weaknesses, etc. These changes


00:10:20.000 --> 00:10:22.150
are more exaggerated with long duration


00:10:22.160 --> 00:10:23.910
flight in the International Space


00:10:23.920 --> 00:10:26.470
Station. The vision problems are called


00:10:26.480 --> 00:10:30.069
SANS, SNS, which is an acronym for


00:10:30.079 --> 00:10:33.190
spaceflight associated neuroccular


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syndrome. Our lab is studying that as


00:10:36.320 --> 00:10:38.550
well. That's a whole other fascinating


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issue.


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I could tell you some fun stories about


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astronauts and how weird some of them


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feel when they get back. Maybe we need


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to get Heidi on the show.


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>> Maybe we do.


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>> Yeah. No, that's um that's uh she has


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another interesting comment actually


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about the uh about the uh Voyager Golden


00:10:57.360 --> 00:10:59.110
Record, but we might talk about that


00:10:59.120 --> 00:11:00.150
another time.


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>> Fair enough. Yeah. All right. Thank you,


00:11:01.680 --> 00:11:03.990
Heidi. That was fascinating. Yeah. Um


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what a what an amazing job working with


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all those incredible people


00:11:08.720 --> 00:11:10.230
trying to figure out how to deal with


00:11:10.240 --> 00:11:13.190
the zerog problem. But uh on Mars the


00:11:13.200 --> 00:11:15.990
gravity will also be an issue. So um


00:11:16.000 --> 00:11:17.829
there's there's a heck of a lot that


00:11:17.839 --> 00:11:21.590
needs to be sorted out before we um


00:11:21.600 --> 00:11:24.230
>> put people down there because it it it's


00:11:24.240 --> 00:11:25.829
so such a long trip to get there. It's


00:11:25.839 --> 00:11:27.350
not like you can go ah no this is no


00:11:27.360 --> 00:11:28.790
good and come straight back. It's not


00:11:28.800 --> 00:11:30.069
going to be that simple.


00:11:30.079 --> 00:11:31.430
>> No, that's right. Once you're on your


00:11:31.440 --> 00:11:33.030
way, you're on your way. And the only


00:11:33.040 --> 00:11:35.110
way back is to keep going.


00:11:35.120 --> 00:11:37.430
>> Yeah, exactly. Thanks for the question,


00:11:37.440 --> 00:11:40.310
John. Uh, well asked. And, uh, yeah,


00:11:40.320 --> 00:11:42.389
it's not going to be a snack, that's for


00:11:42.399 --> 00:11:44.870
sure. Let's, uh, move on to our next


00:11:44.880 --> 00:11:48.470
question from Dan. Hello, gentlemen. Dan


00:11:48.480 --> 00:11:50.870
from the Gold Coast here. Uh, now, I


00:11:50.880 --> 00:11:53.910
know you've been asked a million


00:11:53.920 --> 00:11:56.310
questions about black holes. Uh, but I


00:11:56.320 --> 00:11:57.990
do have a quick two-parter, and I'm


00:11:58.000 --> 00:11:59.269
hoping it's something you've never had


00:11:59.279 --> 00:12:02.069
to answer before. really quickly from


00:12:02.079 --> 00:12:05.190
the point when a black hole is born,


00:12:05.200 --> 00:12:06.710
birth, created, whatever you want to


00:12:06.720 --> 00:12:09.269
call it. Uh how quickly is that growing


00:12:09.279 --> 00:12:11.509
to become a let's say super massive


00:12:11.519 --> 00:12:12.790
black hole or just something a lot


00:12:12.800 --> 00:12:16.949
bigger? Um or is that not how black


00:12:16.959 --> 00:12:18.550
holes work and I'm not understanding it


00:12:18.560 --> 00:12:22.310
properly? two, uh, hypothetically, if


00:12:22.320 --> 00:12:24.949
there's no matter or energy or anything


00:12:24.959 --> 00:12:28.150
surrounding the black hole to take in


00:12:28.160 --> 00:12:31.509
and let's say eat, uh, is the black hole


00:12:31.519 --> 00:12:33.509
still going to grow? Is there more to


00:12:33.519 --> 00:12:36.470
the black hole growing than I


00:12:36.480 --> 00:12:39.269
understand? Um, yeah, hopefully that


00:12:39.279 --> 00:12:40.550
made sense and hopefully it's worth


00:12:40.560 --> 00:12:43.190
answering. Love the show. Love you guys


00:12:43.200 --> 00:12:45.509
work. Cheers. Bye.


00:12:45.519 --> 00:12:47.509
>> Thank you, Dan. Uh, nice to hear from


00:12:47.519 --> 00:12:50.470
you. Uh yeah, a couple of questions in


00:12:50.480 --> 00:12:52.710
that one. Um we never talk about black


00:12:52.720 --> 00:12:55.750
holes, but we will today. Uh speed of


00:12:55.760 --> 00:12:59.590
growth. Um that's an interesting one. Uh


00:12:59.600 --> 00:13:01.910
given that we're starting to think that


00:13:01.920 --> 00:13:06.470
there were some absolutely enormous


00:13:06.480 --> 00:13:09.430
um black holes in the early universe.


00:13:09.440 --> 00:13:13.350
Um and and that they're looking for more


00:13:13.360 --> 00:13:14.790
and more evidence to see what was going


00:13:14.800 --> 00:13:17.590
on early on. Um, but we've got some


00:13:17.600 --> 00:13:21.030
gargantuan ones still around. Uh, so how


00:13:21.040 --> 00:13:24.150
fast did they get that big? And I I I'm


00:13:24.160 --> 00:13:26.310
starting to think, Fred, it wouldn't be


00:13:26.320 --> 00:13:28.870
a stock standard approach.


00:13:28.880 --> 00:13:31.269
Maybe not. Maybe not. Uh, but well, I


00:13:31.279 --> 00:13:34.069
mean, Dan's asking uh one of the


00:13:34.079 --> 00:13:35.910
fundamental questions of astrophysics at


00:13:35.920 --> 00:13:37.829
the moment. This is a very hot topic.


00:13:37.839 --> 00:13:39.750
Yeah. And what set the cat among the


00:13:39.760 --> 00:13:41.590
pigeons and made it a hot topic is the


00:13:41.600 --> 00:13:44.790
James Web Space Telescope because um


00:13:44.800 --> 00:13:48.629
until that came along, the idea was that


00:13:48.639 --> 00:13:51.350
as basically as Dan suggests, black


00:13:51.360 --> 00:13:54.949
holes were formed in the early universe


00:13:54.959 --> 00:13:58.389
by exploding stars that um collapsed at


00:13:58.399 --> 00:14:00.470
the end of their lives to to form a


00:14:00.480 --> 00:14:02.470
black hole. the core would collapse to a


00:14:02.480 --> 00:14:05.750
black hole and that then over over


00:14:05.760 --> 00:14:07.990
billions of years that black hole would


00:14:08.000 --> 00:14:10.790
grow and eventually in our own epoch


00:14:10.800 --> 00:14:13.670
today 13.8 billion years after the after


00:14:13.680 --> 00:14:16.470
the big bang uh you have super massive


00:14:16.480 --> 00:14:17.990
black holes at the center of every


00:14:18.000 --> 00:14:21.110
galaxy. That was the old wisdom. But the


00:14:21.120 --> 00:14:22.710
James Webb telescope has turned that


00:14:22.720 --> 00:14:25.590
completely on its head because we have


00:14:25.600 --> 00:14:28.230
serious evidence of super massive black


00:14:28.240 --> 00:14:32.230
holes within the first 500 million years


00:14:32.240 --> 00:14:34.949
of the universe's existence. And that's


00:14:34.959 --> 00:14:39.110
too quick for or too short a time for


00:14:39.120 --> 00:14:42.389
this um you know the this slow accretion


00:14:42.399 --> 00:14:46.389
of of stuff uh as being the um the the


00:14:46.399 --> 00:14:49.110
the growth mechanism for black holes. Uh


00:14:49.120 --> 00:14:50.949
it's too too short a time for that to be


00:14:50.959 --> 00:14:55.910
the case. Uh so either our ideas of how


00:14:55.920 --> 00:14:59.350
fast they gobble up matter is wrong and


00:14:59.360 --> 00:15:01.269
they gobble up faster matter a lot


00:15:01.279 --> 00:15:02.870
faster than we thought. And we actually


00:15:02.880 --> 00:15:05.030
covered a story on this I think about


00:15:05.040 --> 00:15:07.670
four or five episodes ago because there


00:15:07.680 --> 00:15:10.069
are some scientists who came to


00:15:10.079 --> 00:15:11.990
conclusion that one of the things that


00:15:12.000 --> 00:15:15.189
we thought limited how fast a black hole


00:15:15.199 --> 00:15:17.509
can gobble stuff up uh was actually


00:15:17.519 --> 00:15:20.470
invalid under certain circumstances.


00:15:20.480 --> 00:15:23.750
>> So that's that's one avenue of research


00:15:23.760 --> 00:15:26.310
that's come from the James Web telescope


00:15:26.320 --> 00:15:28.150
showing us that we've got these super


00:15:28.160 --> 00:15:29.430
massive black holes in the early


00:15:29.440 --> 00:15:31.509
universe. But the other one is the the


00:15:31.519 --> 00:15:33.910
idea of the little pink dots or the


00:15:33.920 --> 00:15:35.990
little red dots as they're called. And


00:15:36.000 --> 00:15:39.829
these are thought to be basically just


00:15:39.839 --> 00:15:43.189
clouds of gas, hydrogen gas, which are


00:15:43.199 --> 00:15:46.150
directly feeding a black hole that may


00:15:46.160 --> 00:15:48.310
have been formed in the Big Bang. In


00:15:48.320 --> 00:15:49.910
other words, you didn't have to have


00:15:49.920 --> 00:15:52.870
star formation and then stars blowing up


00:15:52.880 --> 00:15:55.030
to create back black holes in order to


00:15:55.040 --> 00:15:57.350
kick this process off. the big bang


00:15:57.360 --> 00:15:59.110
itself might have kicked off the process


00:15:59.120 --> 00:16:00.949
of black hole formation by producing


00:16:00.959 --> 00:16:03.189
these things that we call primordial


00:16:03.199 --> 00:16:07.749
black holes. Um and they may have turned


00:16:07.759 --> 00:16:10.629
out to be able to grow very quickly uh


00:16:10.639 --> 00:16:13.749
by immersing themselves simply in big


00:16:13.759 --> 00:16:15.990
clouds of hydrogen and gobbling it all


00:16:16.000 --> 00:16:16.550
up.


00:16:16.560 --> 00:16:20.470
>> Yeah. Of course uh when they run out of


00:16:20.480 --> 00:16:23.189
stuff they can't grow. Is that right?


00:16:23.199 --> 00:16:25.269
>> That's right. So, that's part two of


00:16:25.279 --> 00:16:28.150
Dan's question. Uh, what happens when


00:16:28.160 --> 00:16:29.509
there's nothing there for them to eat?


00:16:29.519 --> 00:16:31.430
And they become what we call quiescent


00:16:31.440 --> 00:16:33.910
black holes. They they they don't do


00:16:33.920 --> 00:16:36.389
anything. They're there. Uh, and they're


00:16:36.399 --> 00:16:39.430
still things that um if if a cloud of


00:16:39.440 --> 00:16:42.389
hydrogen strayed by, they they might


00:16:42.399 --> 00:16:44.150
seize it by their own gravity and pull


00:16:44.160 --> 00:16:45.189
it in. Yeah.


00:16:45.199 --> 00:16:47.749
>> But, um, they're not going to go out


00:16:47.759 --> 00:16:49.910
roaming through the um roaming through


00:16:49.920 --> 00:16:51.990
the universe looking for stuff to


00:16:52.000 --> 00:16:53.590
accrete. In other words, looking for a


00:16:53.600 --> 00:16:54.310
snap.


00:16:54.320 --> 00:16:56.790
>> Yeah. I used to work with a guy whose


00:16:56.800 --> 00:16:58.629
nickname was queercent black hole. He


00:16:58.639 --> 00:17:03.189
was there, but he didn't do anything.


00:17:03.199 --> 00:17:08.390
>> Yes, I think I know who you mean.


00:17:08.400 --> 00:17:11.110
Yeah. Anyway, quent black holes are


00:17:11.120 --> 00:17:13.829
basically what what Dan has described.


00:17:13.839 --> 00:17:15.750
But the first part of his question is


00:17:15.760 --> 00:17:17.829
absolutely asking the same questions


00:17:17.839 --> 00:17:20.069
that today's astrophysicists are. It's


00:17:20.079 --> 00:17:22.630
one whose answer we don't know. But the


00:17:22.640 --> 00:17:24.549
contentus will emerge over the next


00:17:24.559 --> 00:17:26.309
probably not very long because we're


00:17:26.319 --> 00:17:28.230
getting so much data from the James Webb


00:17:28.240 --> 00:17:29.430
telescope


00:17:29.440 --> 00:17:30.870
>> uh that I think it'll be quite soon


00:17:30.880 --> 00:17:32.710
before this whole issue is resolved.


00:17:32.720 --> 00:17:34.630
>> I would think sorry


00:17:34.640 --> 00:17:36.470
>> I was just going to say when when there


00:17:36.480 --> 00:17:38.630
is hard evidence of a primordial black


00:17:38.640 --> 00:17:40.549
hole being discovered, one that was


00:17:40.559 --> 00:17:43.430
created in the Big Bang, then that'll be


00:17:43.440 --> 00:17:45.669
Nobel Prizewinning science when we get


00:17:45.679 --> 00:17:47.270
to that stage.


00:17:47.280 --> 00:17:48.310
>> But it won't be us.


00:17:48.320 --> 00:17:50.630
>> Indeed. I was going to suggest that um


00:17:50.640 --> 00:17:53.029
black holes are probably like humans.


00:17:53.039 --> 00:17:54.710
Consumption will decide how big they


00:17:54.720 --> 00:17:56.070
get.


00:17:56.080 --> 00:17:57.510
>> Maybe that's right.


00:17:57.520 --> 00:17:58.549
>> Yeah. Yeah.


00:17:58.559 --> 00:18:01.029
>> We'll have to wait and see. All right,


00:18:01.039 --> 00:18:03.029
Dan. Uh hopefully we covered that for


00:18:03.039 --> 00:18:05.590
you adequately. Thanks for sending in


00:18:05.600 --> 00:18:07.669
the question. This is Space Nuts with


00:18:07.679 --> 00:18:12.710
Andrew Dunley and Professor Fred Watson.


00:18:12.720 --> 00:18:15.510
>> Three, two, one.


00:18:15.520 --> 00:18:18.950
>> Space nuts. Our next question, Fred,


00:18:18.960 --> 00:18:21.830
comes from Thomas Reed. Thomas is 11


00:18:21.840 --> 00:18:23.909
years old. He says, "Something has been


00:18:23.919 --> 00:18:25.750
troubling me in books I've read. They


00:18:25.760 --> 00:18:28.390
say that the centers of galaxies are


00:18:28.400 --> 00:18:30.789
very big black holes, and I have a few


00:18:30.799 --> 00:18:32.870
questions about them, but I'm only an


00:18:32.880 --> 00:18:35.110
11year-old kid, so the questions might


00:18:35.120 --> 00:18:36.870
sound silly, but here they are. Now, we


00:18:36.880 --> 00:18:38.950
got five questions, Fred, so we can be


00:18:38.960 --> 00:18:41.029
brief on them on them, unless you want


00:18:41.039 --> 00:18:43.750
to sit here another couple of hours. Um,


00:18:43.760 --> 00:18:45.510
if Jy was here, we would be a couple of


00:18:45.520 --> 00:18:46.710
hours.


00:18:46.720 --> 00:18:49.510
Um, can the galactic centers swallow all


00:18:49.520 --> 00:18:51.909
the stars and planets in the galaxy? How


00:18:51.919 --> 00:18:54.230
big are the galactic centers or do we


00:18:54.240 --> 00:18:56.710
not know? Uh, if they can swallow up all


00:18:56.720 --> 00:18:59.270
the stars and planets, is there a limit?


00:18:59.280 --> 00:19:01.990
If there is a limit, what is it? And if


00:19:02.000 --> 00:19:04.230
there is a limit, what happens when the


00:19:04.240 --> 00:19:06.390
limit is reached? Thank you for taking


00:19:06.400 --> 00:19:08.150
the time to read this. And I would love


00:19:08.160 --> 00:19:09.990
it if you could reply. Well, we are


00:19:10.000 --> 00:19:13.750
going to reply right now, Thomas. Um,


00:19:13.760 --> 00:19:15.909
yeah, it's uh it's great that uh


00:19:15.919 --> 00:19:18.230
somebody so young is is taking a keen


00:19:18.240 --> 00:19:20.470
interest in something so mysterious as a


00:19:20.480 --> 00:19:23.270
as a black hole. Uh we want to start at


00:19:23.280 --> 00:19:25.029
the top. Can the galactic center swallow


00:19:25.039 --> 00:19:27.430
all the stars and planets in the galaxy?


00:19:27.440 --> 00:19:30.230
>> Well, so the answer is no. Um so the


00:19:30.240 --> 00:19:32.549
galaxies are very big. Um ours is about


00:19:32.559 --> 00:19:35.270
100,000 light years across. Uh, black


00:19:35.280 --> 00:19:38.549
holes have a a kind of sphere of


00:19:38.559 --> 00:19:41.510
influence um, which gravitationally


00:19:41.520 --> 00:19:43.430
stretches to the edge of the galaxy, but


00:19:43.440 --> 00:19:45.510
by the time you get there, the gravity


00:19:45.520 --> 00:19:47.270
of the black hole is very very weak


00:19:47.280 --> 00:19:50.630
indeed. Uh, and so it's only in the


00:19:50.640 --> 00:19:53.350
central region of a galaxy where you


00:19:53.360 --> 00:19:55.909
could get material being swallowed up


00:19:55.919 --> 00:19:58.470
uh, to create this activity that we talk


00:19:58.480 --> 00:19:59.830
about when we talk about active black


00:19:59.840 --> 00:20:03.029
holes. uh where there's uh an accretion


00:20:03.039 --> 00:20:05.270
disc, a disc of material swirling around


00:20:05.280 --> 00:20:08.070
it and these jets that point basically


00:20:08.080 --> 00:20:09.750
at right angles to the accretion disc.


00:20:09.760 --> 00:20:11.510
Jets of material traveling at nearly the


00:20:11.520 --> 00:20:13.590
speed of light. Quite extraordinary.


00:20:13.600 --> 00:20:16.549
>> So, um that's all great and a black hole


00:20:16.559 --> 00:20:18.390
is like a factory or a furnace doing


00:20:18.400 --> 00:20:20.870
that, but it's it stretch is not very


00:20:20.880 --> 00:20:24.070
far. Uh it's measured in light years,


00:20:24.080 --> 00:20:25.590
but not in hundreds of thousands of


00:20:25.600 --> 00:20:27.669
light years, which you'd have to be to


00:20:27.679 --> 00:20:29.669
to grab everything in the galaxy. So the


00:20:29.679 --> 00:20:32.310
answer is no. Uh the galactic center


00:20:32.320 --> 00:20:34.630
black hole cannot swallow all the stars


00:20:34.640 --> 00:20:36.630
and planets in the galaxy.


00:20:36.640 --> 00:20:39.190
>> So So Thomas can sleep well tonight. Um


00:20:39.200 --> 00:20:41.350
how big are the galactic centers? Do we


00:20:41.360 --> 00:20:43.830
know how big?


00:20:43.840 --> 00:20:47.270
>> We do. Yes, we do because we can measure


00:20:47.280 --> 00:20:50.470
we can measure the uh the speed of


00:20:50.480 --> 00:20:54.070
rotation of stuff swirling around a


00:20:54.080 --> 00:20:56.310
black hole if it's an active one.


00:20:56.320 --> 00:20:58.470
>> Yeah. And that directly tells you the


00:20:58.480 --> 00:21:01.830
mass of the black hole. Um because the


00:21:01.840 --> 00:21:03.510
bigger the black hole the faster the


00:21:03.520 --> 00:21:07.110
stuff is going. And so um in terms of


00:21:07.120 --> 00:21:10.549
you know if the if if by big Thomas


00:21:10.559 --> 00:21:13.669
means what's their mass uh we can we can


00:21:13.679 --> 00:21:16.070
measure them quite accurately. Now


00:21:16.080 --> 00:21:18.310
because we can measure their mass we can


00:21:18.320 --> 00:21:20.870
also work out their event horizon


00:21:20.880 --> 00:21:24.310
diameter or radius. The event horizon is


00:21:24.320 --> 00:21:26.870
that sort of imaginary sphere around a


00:21:26.880 --> 00:21:29.510
black hole beyond which light cannot


00:21:29.520 --> 00:21:32.230
escape and so it would appear as a dark


00:21:32.240 --> 00:21:35.029
sphere. Um so the event horizon is the


00:21:35.039 --> 00:21:36.950
point of no return for anything going


00:21:36.960 --> 00:21:39.110
into a black hole and it's also the


00:21:39.120 --> 00:21:42.870
point of no escape for for light waves.


00:21:42.880 --> 00:21:45.270
Uh so we can knowing the mass of a black


00:21:45.280 --> 00:21:48.310
hole we can calculate how big that event


00:21:48.320 --> 00:21:50.390
horizon would be. And some of the super


00:21:50.400 --> 00:21:52.950
massive ones are really very big.


00:21:52.960 --> 00:21:55.029
They're measured in light years, tens of


00:21:55.039 --> 00:21:56.310
light years perhaps for the super


00:21:56.320 --> 00:21:57.510
massive black holes.


00:21:57.520 --> 00:22:00.230
>> Yeah, that it's it's a level of enormity


00:22:00.240 --> 00:22:01.990
that you just struggle to get your head


00:22:02.000 --> 00:22:02.630
around.


00:22:02.640 --> 00:22:04.390
>> Yeah. I suppose in terms of the rest of


00:22:04.400 --> 00:22:06.630
Thomas's questions, you've basically


00:22:06.640 --> 00:22:08.710
answered it with the answer to the first


00:22:08.720 --> 00:22:10.390
question cuz he's asking if they can


00:22:10.400 --> 00:22:12.310
swallow all the stars and planets. Is


00:22:12.320 --> 00:22:14.390
there a limit? If there is a limit, what


00:22:14.400 --> 00:22:17.110
is it? Uh and if there is a limit, what


00:22:17.120 --> 00:22:19.190
happens when the limit is reached? Well,


00:22:19.200 --> 00:22:23.430
the limit is probably the local area of


00:22:23.440 --> 00:22:25.590
the center of the galaxy and what's


00:22:25.600 --> 00:22:27.029
available to eat.


00:22:27.039 --> 00:22:28.950
>> Yes, that's right. So the the limit the


00:22:28.960 --> 00:22:33.669
limiting factor is um basically the the


00:22:33.679 --> 00:22:35.110
what you might call the grasp of the


00:22:35.120 --> 00:22:37.830
black hole. How how far it can reach to


00:22:37.840 --> 00:22:40.870
pull something in. And that is dependent


00:22:40.880 --> 00:22:43.510
on how fast the objects are moving. So


00:22:43.520 --> 00:22:45.270
you can have some stars and there are


00:22:45.280 --> 00:22:47.190
some we've observed them uh with


00:22:47.200 --> 00:22:50.310
infrared radiation that are comfortably


00:22:50.320 --> 00:22:54.789
in orbit uh around the the black hole at


00:22:54.799 --> 00:22:56.870
the center of our own galaxy which are


00:22:56.880 --> 00:22:58.710
not being pulled in. They're orbiting


00:22:58.720 --> 00:23:00.390
and that's because their speed is enough


00:23:00.400 --> 00:23:02.470
to keep them out of the out of the grasp


00:23:02.480 --> 00:23:05.270
of the black hole. um their distances


00:23:05.280 --> 00:23:07.510
from the black hole are measured, you


00:23:07.520 --> 00:23:09.510
know, in not two dissimilar units from


00:23:09.520 --> 00:23:11.430
the from the solar system, sort of half


00:23:11.440 --> 00:23:14.230
a light day or something like that, you


00:23:14.240 --> 00:23:17.430
know, light light day. That's that's the


00:23:17.440 --> 00:23:18.789
sort of measures that we're talking


00:23:18.799 --> 00:23:19.830
about.


00:23:19.840 --> 00:23:22.870
>> Um which probably denies what I just


00:23:22.880 --> 00:23:25.270
said a few minutes ago about um some


00:23:25.280 --> 00:23:27.750
black hole event horizons being tens of


00:23:27.760 --> 00:23:29.110
light years. I don't think they are. I


00:23:29.120 --> 00:23:30.390
think they're smaller than that.


00:23:30.400 --> 00:23:32.390
>> Okay. I've thought of a way to explain


00:23:32.400 --> 00:23:34.470
it to Thomas. say, "Uh, Thomas, you've


00:23:34.480 --> 00:23:37.510
won a competition and you can go to


00:23:37.520 --> 00:23:40.549
McDonald's and eat everything you want."


00:23:40.559 --> 00:23:43.029
Absolutely. Just keep eating until you


00:23:43.039 --> 00:23:45.830
know the cows come home. However, you


00:23:45.840 --> 00:23:47.830
aren't allowed to move from wherever


00:23:47.840 --> 00:23:49.510
you're standing and you can only eat


00:23:49.520 --> 00:23:52.230
what's within reach.


00:23:52.240 --> 00:23:54.870
Once you run out of food, you stop


00:23:54.880 --> 00:23:57.270
growing. And you're the black hole, by


00:23:57.280 --> 00:23:59.350
the way. How's that for an analogy?


00:23:59.360 --> 00:24:00.630
>> It's a nice one. I like it.


00:24:00.640 --> 00:24:03.270
>> Yes. Yeah. Because the your reach is the


00:24:03.280 --> 00:24:04.549
sort of gravitational


00:24:04.559 --> 00:24:04.950
>> Yeah.


00:24:04.960 --> 00:24:06.470
>> force that you can exert. Yeah, it's a


00:24:06.480 --> 00:24:07.750
good way of putting it, Andrew. Well


00:24:07.760 --> 00:24:08.950
done. You should be on the reach.


00:24:08.960 --> 00:24:11.110
>> I try to think on 11y old level, but I'm


00:24:11.120 --> 00:24:12.789
I'm thinking Thomas was probably much


00:24:12.799 --> 00:24:15.430
brighter at 11 than I was.


00:24:15.440 --> 00:24:17.669
>> Struggle to get to 11. So do I.


00:24:17.679 --> 00:24:19.990
>> Yes. Thanks, Thomas. That was really


00:24:20.000 --> 00:24:21.750
terrific. Thanks for sending it in. And


00:24:21.760 --> 00:24:25.830
uh keep on listening.


00:24:25.840 --> 00:24:27.830
>> Swiftity


00:24:27.840 --> 00:24:30.390
base here. The angle has landed. Space


00:24:30.400 --> 00:24:31.430
Nuts.


00:24:31.440 --> 00:24:35.190
>> Final question, Fred, comes from Paul.


00:24:35.200 --> 00:24:37.269
Hello, Space Nuts. Paul here from sunny


00:24:37.279 --> 00:24:38.630
Bris Vegas, where it's currently


00:24:38.640 --> 00:24:40.950
bucketing down in what is being


00:24:40.960 --> 00:24:45.269
described as a rare rain occurrence.


00:24:45.279 --> 00:24:47.190
Anyway,


00:24:47.200 --> 00:24:50.470
I am currently looking through a very


00:24:50.480 --> 00:24:53.510
old book of mine. Guess it's old


00:24:53.520 --> 00:24:56.149
compared to the students I teach. It was


00:24:56.159 --> 00:24:58.549
published back in 1978. I think I got in


00:24:58.559 --> 00:25:01.909
in 1980 from uh an uncle of mine, Uncle


00:25:01.919 --> 00:25:03.510
Jim. Thank you very much. It's called


00:25:03.520 --> 00:25:05.269
Stars and Planets, and it's probably


00:25:05.279 --> 00:25:09.110
what got me into the whole field of


00:25:09.120 --> 00:25:11.510
astronomy in the first place, at least


00:25:11.520 --> 00:25:16.070
my interest in astronomy, obviously. Uh


00:25:16.080 --> 00:25:18.870
very very grateful. I'm on the page


00:25:18.880 --> 00:25:20.870
where it's talking about how the


00:25:20.880 --> 00:25:24.870
American astronomer Harlo Shepley


00:25:24.880 --> 00:25:28.950
used the 1.5 m reflector on top of Mount


00:25:28.960 --> 00:25:31.750
Wilson in California


00:25:31.760 --> 00:25:35.510
to work out that our sun is not at the


00:25:35.520 --> 00:25:37.590
center of our galaxy as was previously


00:25:37.600 --> 00:25:39.990
thought, but is about 2/3 of the way to


00:25:40.000 --> 00:25:43.909
the edge. Could you please give us some


00:25:43.919 --> 00:25:48.789
idea how he actually managed to do that?


00:25:48.799 --> 00:25:52.230
Was it something about the density of


00:25:52.240 --> 00:25:55.269
stars? I mean, how many stars in the


00:25:55.279 --> 00:25:57.350
field of view uh when you point it one


00:25:57.360 --> 00:25:59.669
way compared to the other? How did he do


00:25:59.679 --> 00:26:01.909
it? I'm really curious. And I know I


00:26:01.919 --> 00:26:03.750
could Google it, but I'd rather hear it


00:26:03.760 --> 00:26:07.029
from you guys. So, thanks in advance.


00:26:07.039 --> 00:26:10.870
love the show and dare I say, keep up


00:26:10.880 --> 00:26:13.510
the good work. Cheers.


00:26:13.520 --> 00:26:15.430
>> Cheers, Paul. Thanks for sending that


00:26:15.440 --> 00:26:18.549
in, uh, sending the question in and, uh,


00:26:18.559 --> 00:26:21.669
we don't know the answer. So,


00:26:21.679 --> 00:26:24.710
but we're going to Google it. No. Um,


00:26:24.720 --> 00:26:28.149
1978, Stars and Planets. Uh, I tried to


00:26:28.159 --> 00:26:30.710
look it up. There are teen books named


00:26:30.720 --> 00:26:31.830
Stars and Planets.


00:26:31.840 --> 00:26:32.230
>> Yeah.


00:26:32.240 --> 00:26:34.390
>> So, I haven't been able to, you know,


00:26:34.400 --> 00:26:36.310
distinguish one from the other as yet.


00:26:36.320 --> 00:26:39.590
So um uh yeah, you'll have to do some


00:26:39.600 --> 00:26:41.830
fishing to find the book that Paul was


00:26:41.840 --> 00:26:44.789
talking about. But he wanted to know


00:26:44.799 --> 00:26:48.470
about the man who decided or discovered


00:26:48.480 --> 00:26:50.470
that the sun was not the center of


00:26:50.480 --> 00:26:53.990
everything. Uh which was a common belief


00:26:54.000 --> 00:26:55.830
back in the day.


00:26:55.840 --> 00:26:58.470
>> It was um it was actually 1919 when that


00:26:58.480 --> 00:26:59.909
discovery was made. Um


00:26:59.919 --> 00:27:01.590
>> is it was it that recent?


00:27:01.600 --> 00:27:04.390
>> Yeah. Um I I it's one of my favorite


00:27:04.400 --> 00:27:06.070
astronomical discoveries, which is why I


00:27:06.080 --> 00:27:07.830
didn't need to go to Google to look it


00:27:07.840 --> 00:27:11.990
up. Um so it goes back to the time of


00:27:12.000 --> 00:27:16.070
William Hershel, uh who was a


00:27:16.080 --> 00:27:19.269
German turned British astronomer,


00:27:19.279 --> 00:27:22.070
worked late in the 18th century and


00:27:22.080 --> 00:27:23.750
early in the 19th century. He discovered


00:27:23.760 --> 00:27:26.710
the planet Uranus in 1781.


00:27:26.720 --> 00:27:28.470
But what he was doing when he discovered


00:27:28.480 --> 00:27:30.789
Uranus was actually mapping the Milky


00:27:30.799 --> 00:27:34.630
Way. He was observing uh the the Milky


00:27:34.640 --> 00:27:36.950
Way in a very systematic way with a


00:27:36.960 --> 00:27:39.350
relatively small telescope. So he sort


00:27:39.360 --> 00:27:42.870
of counting stars in the field of view


00:27:42.880 --> 00:27:44.710
of his telescope and then moving the


00:27:44.720 --> 00:27:46.549
telescope a bit further along the Milky


00:27:46.559 --> 00:27:48.789
Way. Counting stars again, how many he


00:27:48.799 --> 00:27:51.110
could see in the field of view and doing


00:27:51.120 --> 00:27:52.870
that and doing it. He couldn't do it all


00:27:52.880 --> 00:27:54.149
the way around the Milky Way because


00:27:54.159 --> 00:27:55.590
there's parts of it that he he could


00:27:55.600 --> 00:27:56.630
never see because they're in the


00:27:56.640 --> 00:27:58.870
southern hemisphere. But he got round


00:27:58.880 --> 00:28:01.430
most of it. And what he discovered was


00:28:01.440 --> 00:28:04.950
that the star counts are pretty even all


00:28:04.960 --> 00:28:06.789
the way around.


00:28:06.799 --> 00:28:09.909
>> And so that led him to build the


00:28:09.919 --> 00:28:12.470
hypothesis that the stars are in a sort


00:28:12.480 --> 00:28:15.110
of flattened disc, which is correct, uh,


00:28:15.120 --> 00:28:17.029
but that we're very near the middle,


00:28:17.039 --> 00:28:20.710
which is not correct. And the reason why


00:28:20.720 --> 00:28:23.269
he got that erroneous answer was that


00:28:23.279 --> 00:28:25.269
when you look through a I think it was a


00:28:25.279 --> 00:28:28.149
7-in telescope if I remember rightly a


00:28:28.159 --> 00:28:30.710
telescope of that size at the Milky Way,


00:28:30.720 --> 00:28:33.430
the stars that you see are all


00:28:33.440 --> 00:28:36.549
relatively nearby. They're perhaps a


00:28:36.559 --> 00:28:38.070
thousand light years away or something


00:28:38.080 --> 00:28:40.630
like that, maybe a bit more, maybe a


00:28:40.640 --> 00:28:42.310
couple of thousand light years away in


00:28:42.320 --> 00:28:44.470
the plane of the Milky Way. And that's


00:28:44.480 --> 00:28:46.389
partly because the Milky Way is very


00:28:46.399 --> 00:28:48.549
dusty. Uh there's a lot of dust


00:28:48.559 --> 00:28:50.070
everywhere. It's probably better


00:28:50.080 --> 00:28:52.389
described as smoke, but we call it dust


00:28:52.399 --> 00:28:54.870
in the world of astronomy. And so that


00:28:54.880 --> 00:28:57.750
dust limits how far you can see. And so


00:28:57.760 --> 00:28:59.669
when you look at the Milky Way, it does


00:28:59.679 --> 00:29:01.909
look generally relatively even. There's


00:29:01.919 --> 00:29:03.430
one bit in the constellation of


00:29:03.440 --> 00:29:05.830
Sagittarius where it's it's brighter and


00:29:05.840 --> 00:29:07.430
that's because you are looking towards


00:29:07.440 --> 00:29:09.830
as we now know the galactic center. But


00:29:09.840 --> 00:29:12.789
um Hershel um he couldn't see that very


00:29:12.799 --> 00:29:13.990
well from the northern hemisphere


00:29:14.000 --> 00:29:16.870
anyway. But he did sort of discount that


00:29:16.880 --> 00:29:19.990
uh he said by and large it's the same


00:29:20.000 --> 00:29:21.830
count all the way around. So we must be


00:29:21.840 --> 00:29:25.590
in the middle. Uh roll on the the years


00:29:25.600 --> 00:29:28.710
and in 1919 Harlo Shappley a very gifted


00:29:28.720 --> 00:29:30.310
American astronomer although he did get


00:29:30.320 --> 00:29:33.350
one thing one big thing wrong. Uh but


00:29:33.360 --> 00:29:36.389
what he did was he was interested in


00:29:36.399 --> 00:29:38.630
objects that we call globular clusters.


00:29:38.640 --> 00:29:40.389
And so these are in fact they were named


00:29:40.399 --> 00:29:42.149
by William Hershel. He gave them that


00:29:42.159 --> 00:29:44.310
name clusters of stars that appear like


00:29:44.320 --> 00:29:49.110
a globe. Uh and uh her halos Shappley


00:29:49.120 --> 00:29:52.230
was uh obser he like he was interested


00:29:52.240 --> 00:29:54.149
in globular clusters. He noticed there


00:29:54.159 --> 00:29:59.350
were a lot of them in our skies. Uh they


00:29:59.360 --> 00:30:02.230
tended to be different sizes.


00:30:02.240 --> 00:30:04.549
Uh and he didn't know whether that was


00:30:04.559 --> 00:30:06.230
cuz they were all the same size and some


00:30:06.240 --> 00:30:08.070
were nearer than others or whether they


00:30:08.080 --> 00:30:10.549
were intrinsically different sizes. But


00:30:10.559 --> 00:30:12.789
what he did notice was that there's a


00:30:12.799 --> 00:30:15.990
concentration of them in the southern


00:30:16.000 --> 00:30:19.350
hemisphere sky. Uh he was observing from


00:30:19.360 --> 00:30:21.590
California, so he could see a fair swath


00:30:21.600 --> 00:30:23.909
of the southern hemisphere sky. But he


00:30:23.919 --> 00:30:26.230
he noticed that they were concentrated


00:30:26.240 --> 00:30:28.389
in that direction and that made him


00:30:28.399 --> 00:30:32.310
wonder if that was where the center of


00:30:32.320 --> 00:30:34.310
the galaxy lay rather than us being near


00:30:34.320 --> 00:30:38.149
the center. Uh but then his other step


00:30:38.159 --> 00:30:41.110
was that he recognized that within these


00:30:41.120 --> 00:30:43.590
globular clusters were something called


00:30:43.600 --> 00:30:46.710
clust they called them cluster variables


00:30:46.720 --> 00:30:49.430
stars that varied in a certain way on a


00:30:49.440 --> 00:30:52.470
with a periodicity of about a day. Uh


00:30:52.480 --> 00:30:55.110
today we call them rli variables and I


00:30:55.120 --> 00:30:56.549
actually started my astronomical


00:30:56.559 --> 00:30:58.710
research back in the 70s studying these


00:30:58.720 --> 00:31:03.669
things. uh rlari variables uh and they


00:31:03.679 --> 00:31:07.750
they are good because they've got a


00:31:07.760 --> 00:31:11.269
basically a known distance uh if you if


00:31:11.279 --> 00:31:13.830
you can see an RLI variable and identify


00:31:13.840 --> 00:31:16.149
it as one you know how intrinsically


00:31:16.159 --> 00:31:19.110
bright it is uh and then from that you


00:31:19.120 --> 00:31:21.750
can work out how far away it is. And so


00:31:21.760 --> 00:31:24.149
he found these variable stars in the


00:31:24.159 --> 00:31:27.269
globular clusters and recognized that he


00:31:27.279 --> 00:31:29.830
could draw a chart with the the globular


00:31:29.840 --> 00:31:32.310
clusters all at their correct distance


00:31:32.320 --> 00:31:34.230
on it, make a kind of three-dimensional


00:31:34.240 --> 00:31:37.590
map of the sky. And sure enough, um they


00:31:37.600 --> 00:31:40.710
concentrated around the galactic center


00:31:40.720 --> 00:31:43.190
around a point. Uh he actually got the


00:31:43.200 --> 00:31:45.269
answer wrong because his magnitude, his


00:31:45.279 --> 00:31:47.509
brightness that he had for the uh


00:31:47.519 --> 00:31:50.310
cluster variables was incorrect. uh and


00:31:50.320 --> 00:31:51.990
I can't remember what answer he got, but


00:31:52.000 --> 00:31:55.909
in modern parliament it's about 25,000


00:31:55.919 --> 00:31:58.870
light years. The cluster, the globular


00:31:58.880 --> 00:32:00.870
clusters themselves cluster around a


00:32:00.880 --> 00:32:03.830
point about 25,000 light years away,


00:32:03.840 --> 00:32:05.750
which is deeply hidden by the dust


00:32:05.760 --> 00:32:08.230
clouds in Sagittarius. So


00:32:08.240 --> 00:32:10.149
>> he figured out that that's where the


00:32:10.159 --> 00:32:12.149
center of the galaxy was. A brilliant


00:32:12.159 --> 00:32:14.149
piece of detective work. We know he was


00:32:14.159 --> 00:32:17.350
right. Uh what he was wrong about was uh


00:32:17.360 --> 00:32:21.830
he had a big discussion I think in 1923


00:32:21.840 --> 00:32:24.310
just before Hubble recognized that


00:32:24.320 --> 00:32:26.389
galaxies were big things a long way


00:32:26.399 --> 00:32:28.549
away. Uh Shappley was arguing that


00:32:28.559 --> 00:32:31.029
galaxies lie within our own Milky Way


00:32:31.039 --> 00:32:32.950
that they're small objects in our own


00:32:32.960 --> 00:32:36.389
Milky Way. And he was um arguing it was


00:32:36.399 --> 00:32:37.990
a public debate actually between


00:32:38.000 --> 00:32:40.870
Chappley and a guy called Hea Curtis. Uh


00:32:40.880 --> 00:32:42.389
Curtis had the answer right. He said


00:32:42.399 --> 00:32:44.789
they're big and a long way off. Uh


00:32:44.799 --> 00:32:46.470
Shappley said, "No, they're small and


00:32:46.480 --> 00:32:48.630
nearby." And it was very soon after that


00:32:48.640 --> 00:32:50.070
that Hubble produced that they're big


00:32:50.080 --> 00:32:52.470
and a long way proved that they're big


00:32:52.480 --> 00:32:53.669
and a long way off.


00:32:53.679 --> 00:32:54.070
>> Yeah.


00:32:54.080 --> 00:32:55.430
>> So Shappley was wrong in that, but he


00:32:55.440 --> 00:32:57.830
was right about the Galactic Center.


00:32:57.840 --> 00:33:00.950
Fantastic. Gee whiz. Um great question,


00:33:00.960 --> 00:33:04.389
Paul. And um yeah, if people are looking


00:33:04.399 --> 00:33:06.710
for that uh that book, Stars and


00:33:06.720 --> 00:33:09.190
Planets, uh it is out there. Uh, look,


00:33:09.200 --> 00:33:10.870
I've I've found a couple that were


00:33:10.880 --> 00:33:13.029
actually published around that time that


00:33:13.039 --> 00:33:15.430
Paul mentioned, but um not sure if


00:33:15.440 --> 00:33:17.110
they're the ones I I can't remember the


00:33:17.120 --> 00:33:19.350
author now um that he said, but


00:33:19.360 --> 00:33:20.950
>> I don't think he mentioned an author,


00:33:20.960 --> 00:33:21.269
did he?


00:33:21.279 --> 00:33:22.870
>> I thought he did, but uh No, he might


00:33:22.880 --> 00:33:25.190
have mentioned an uncle


00:33:25.200 --> 00:33:27.430
mention


00:33:27.440 --> 00:33:28.070
it.


00:33:28.080 --> 00:33:30.710
>> But um


00:33:30.720 --> 00:33:32.789
um so yeah, thanks Paul. Thanks for the


00:33:32.799 --> 00:33:34.950
the question. And um yeah, it's it's a


00:33:34.960 --> 00:33:37.590
fascinating um history in astronomy as


00:33:37.600 --> 00:33:39.269
we discover these things. I think one of


00:33:39.279 --> 00:33:40.950
my favorite


00:33:40.960 --> 00:33:43.509
>> moments I suppose in in astronomical


00:33:43.519 --> 00:33:45.669
history was when they discovered that


00:33:45.679 --> 00:33:48.630
our sun was a star.


00:33:48.640 --> 00:33:50.630
>> Yeah, that was a long long time ago.


00:33:50.640 --> 00:33:51.190
>> Yeah.




00:33:51.679 --> 00:33:53.990
>> But for a while there we didn't think of


00:33:54.000 --> 00:33:54.389
it like that.


00:33:54.399 --> 00:33:55.430
>> Thought it was something else. That's


00:33:55.440 --> 00:33:57.909
right. Something bit special.


00:33:57.919 --> 00:34:00.950
>> Yeah. Um, and and I I saw that on a BBC


00:34:00.960 --> 00:34:02.630
documentary many years ago, and I sat


00:34:02.640 --> 00:34:05.669
there and went, "Wow, I never thought


00:34:05.679 --> 00:34:07.430
about that cuz I've always known it to


00:34:07.440 --> 00:34:10.629
be a star, but for generations, they


00:34:10.639 --> 00:34:12.550
didn't."


00:34:12.560 --> 00:34:14.869
Quite quite intriguing. And why would


00:34:14.879 --> 00:34:16.790
you? It doesn't look like a star.


00:34:16.800 --> 00:34:20.389
>> That's That's right. Uh, it's uh it's


00:34:20.399 --> 00:34:24.069
clearly quite different from a star.


00:34:24.079 --> 00:34:25.669
>> Incredible. Thanks, Paul. Thanks for


00:34:25.679 --> 00:34:27.349
sending that in. And if you have a


00:34:27.359 --> 00:34:29.190
question for a thanks to all our


00:34:29.200 --> 00:34:31.510
senderiners, I've always wanted to say


00:34:31.520 --> 00:34:33.430
that uh for their questions. And if you


00:34:33.440 --> 00:34:34.950
would like to send a question, go to our


00:34:34.960 --> 00:34:37.109
website spaceenutspodcast.com


00:34:37.119 --> 00:34:39.190
or spacenuts.io


00:34:39.200 --> 00:34:42.149
and there's a little AMA tab at the top


00:34:42.159 --> 00:34:44.710
which stands for ask me anything. Not me


00:34:44.720 --> 00:34:48.629
personally, it's the royal me. And um


00:34:48.639 --> 00:34:50.710
just put your uh question in there. It


00:34:50.720 --> 00:34:52.629
can be text or audio. Don't forget to


00:34:52.639 --> 00:34:53.829
tell us who you are and where you're


00:34:53.839 --> 00:34:55.109
from and have a look around while you're


00:34:55.119 --> 00:34:57.829
there. Don't forget to leave a review at


00:34:57.839 --> 00:35:00.550
your favorite podcasting platform. We're


00:35:00.560 --> 00:35:02.150
all done. Thanks, Fred.


00:35:02.160 --> 00:35:05.030
>> A great pleasure, Andrew. We um we uh


00:35:05.040 --> 00:35:07.349
continue to get great questions from


00:35:07.359 --> 00:35:09.109
great listeners and long may it


00:35:09.119 --> 00:35:09.990
continue. Thank you.


00:35:10.000 --> 00:35:12.310
>> Yes, indeed. We we continue to solve and


00:35:12.320 --> 00:35:13.829
evolve.


00:35:13.839 --> 00:35:15.430
Um maybe not.


00:35:15.440 --> 00:35:18.069
>> I'm not evolving.


00:35:18.079 --> 00:35:20.390
>> When once you reach a certain certain


00:35:20.400 --> 00:35:22.630
age, evolving just is not part of the


00:35:22.640 --> 00:35:23.270
program.


00:35:23.280 --> 00:35:24.069
>> That's right.


00:35:24.079 --> 00:35:26.630
>> Yeah. Ask my mom in the internet. Uh,


00:35:26.640 --> 00:35:28.390
thanks Fred. We'll see you soon.


00:35:28.400 --> 00:35:29.750
>> Sounds great. Thanks.


00:35:29.760 --> 00:35:31.430
>> Professor Fred Watson, astronomer at


00:35:31.440 --> 00:35:32.950
large. And thanks to Hugh in the studio.


00:35:32.960 --> 00:35:35.990
He's just turned up. Um, we started 39


00:35:36.000 --> 00:35:38.790
minutes ago. And and um, Hugh set his


00:35:38.800 --> 00:35:41.109
clock to a Martian day. So that's why


00:35:41.119 --> 00:35:43.750
he's 39 minutes late. Boom. Boom. And


00:35:43.760 --> 00:35:45.349
from me, Andrew Dunley, thanks for your


00:35:45.359 --> 00:35:46.950
company. We'll see you on the next


00:35:46.960 --> 00:35:48.950
episode of Space Nuts. Bye-bye.


00:35:48.960 --> 00:35:51.270
>> Space Nuts. You've been listening to the


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Space Nuts podcast. Missing complete


00:35:54.320 --> 00:35:57.270
>> available at Apple Podcasts, Spotify,


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