00:00:00 --> 00:00:01 Hello again and thank you for joining us
00:00:02 --> 00:00:03 on another episode of Space Nuts. This
00:00:03 --> 00:00:06 is a Q&A edition where we take audience
00:00:06 --> 00:00:08 questions, we put them on paper, and
00:00:08 --> 00:00:11 then we put them on a roll that goes on
00:00:11 --> 00:00:14 a little thing in a bathroom.
00:00:14 --> 00:00:16 Or we could answer them. We can do that.
00:00:16 --> 00:00:19 Uh coming up today, we have uh questions
00:00:19 --> 00:00:22 uh from John about Martian days. The
00:00:22 --> 00:00:25 length of a Martian day. It's close, but
00:00:25 --> 00:00:27 is it close enough to Earth's standard?
00:00:27 --> 00:00:31 We'll discuss that. Uh, the growth of a
00:00:31 --> 00:00:34 black hole has been uh brought up again.
00:00:34 --> 00:00:37 Uh, we've got a um a uh question from an
00:00:37 --> 00:00:39 11-year-old named Thomas. Hi, Thomas. He
00:00:39 --> 00:00:42 wants to talk about the galactic center.
00:00:42 --> 00:00:45 And Paul is asking our uh about our
00:00:45 --> 00:00:47 galactic location. So, we'll deal with
00:00:47 --> 00:00:50 all of that today on this episode of
00:00:50 --> 00:00:51 Space Nuts.
00:00:51 --> 00:00:56 >> 15 seconds. Guidance is internal. 10 9
00:00:56 --> 00:00:59 ignition sequence start. Space Nuts.
00:00:59 --> 00:01:01 >> 5 4 3 2
00:01:01 --> 00:01:04 >> 1 2 3 4 5 5 4 3 2 1
00:01:04 --> 00:01:05 >> Space Nuts.
00:01:05 --> 00:01:08 >> Astronauts report. It feels good.
00:01:08 --> 00:01:10 >> Joining us again to sort all of that out
00:01:10 --> 00:01:13 is Professor Fred Watson, astronomer at
00:01:13 --> 00:01:14 large. Hello, Fred.
00:01:14 --> 00:01:16 >> Hello, Andrew. Good to see you again.
00:01:16 --> 00:01:18 >> Good to see you, too.
00:01:18 --> 00:01:20 >> Yes. Despite the hole in my head.
00:01:20 --> 00:01:23 >> Yeah. Yeah. It doesn't look any better
00:01:23 --> 00:01:24 than the last time I show you.
00:01:24 --> 00:01:26 >> It doesn't, does it?
00:01:26 --> 00:01:28 >> No. I mean, you know, it's only been
00:01:28 --> 00:01:30 minutes. You'd think it would have
00:01:30 --> 00:01:32 improved by now.
00:01:32 --> 00:01:34 >> That's what happens when you walk into a
00:01:34 --> 00:01:37 when you walk into a closed screen door.
00:01:37 --> 00:01:37 >> Yeah.
00:01:37 --> 00:01:38 >> In the dark,
00:01:38 --> 00:01:40 >> it hurts.
00:01:40 --> 00:01:44 >> Now, that's why they have stuff um on on
00:01:44 --> 00:01:46 glass sliding doors. You know, that
00:01:46 --> 00:01:48 that's a standard safety standard
00:01:48 --> 00:01:50 required these days so that you know the
00:01:50 --> 00:01:51 door is there.
00:01:51 --> 00:01:52 >> Yeah.
00:01:52 --> 00:01:54 But when it's nighttime and it's a
00:01:54 --> 00:01:56 screen door, not not many excuses left
00:01:56 --> 00:01:58 there, Fred. Really?
00:01:58 --> 00:02:00 >> Only stupidity, I think, is the is the
00:02:00 --> 00:02:03 last one. But that's that's my excuse
00:02:03 --> 00:02:05 many, many times.
00:02:05 --> 00:02:07 >> Yeah. Well, like I said before, we've
00:02:08 --> 00:02:09 all done it.
00:02:09 --> 00:02:11 >> Uh shall we try and answer these
00:02:11 --> 00:02:11 questions?
00:02:11 --> 00:02:12 >> We should.
00:02:12 --> 00:02:14 >> Okay, let's go to question one. This one
00:02:14 --> 00:02:18 comes from John. Uh we know that the
00:02:18 --> 00:02:20 Martian day is 39 minutes longer than an
00:02:20 --> 00:02:23 Earth Day. That's about 4 and 1/2 hours
00:02:23 --> 00:02:27 a week. Uh when and if Mars is populated
00:02:27 --> 00:02:30 with humans, how would we work with the
00:02:30 --> 00:02:32 longer day/week?
00:02:32 --> 00:02:35 Would human biology tend to keep to the
00:02:35 --> 00:02:38 24-hour day or would we adapt to a
00:02:38 --> 00:02:41 longer dayight cycle? Thanks. Love the
00:02:41 --> 00:02:43 show and have been a listener since you
00:02:43 --> 00:02:45 started. Wow, you've got a lot of spare
00:02:45 --> 00:02:49 time, John. Uh thank you so much uh for
00:02:49 --> 00:02:51 sending your question in and hope all is
00:02:51 --> 00:02:55 well. Uh I love this question because it
00:02:55 --> 00:02:58 you've got a planet that is close enough
00:02:58 --> 00:03:00 for us to get to in the not too distant
00:03:00 --> 00:03:02 future. Probably
00:03:02 --> 00:03:04 not a permanent settlement, but a
00:03:04 --> 00:03:07 rotating settlement of some kind will be
00:03:07 --> 00:03:09 the initial stages of humans being on
00:03:09 --> 00:03:11 Mars.
00:03:11 --> 00:03:15 and yet you've got an extra 39 minutes a
00:03:15 --> 00:03:18 day to deal with. What is going to be
00:03:18 --> 00:03:20 the impact?
00:03:20 --> 00:03:22 >> Um I think we've already
00:03:22 --> 00:03:26 >> have um a lot of data on this because
00:03:26 --> 00:03:27 the
00:03:27 --> 00:03:28 >> we've already talked about this once
00:03:28 --> 00:03:31 before in the dead dark past came up
00:03:31 --> 00:03:31 again. Yeah.
00:03:31 --> 00:03:34 >> Yeah. because of the the um um rover
00:03:34 --> 00:03:36 drivers.
00:03:36 --> 00:03:40 >> Uh they um people the people who are uh
00:03:40 --> 00:03:42 in command of if I can put it that way
00:03:42 --> 00:03:43 because they don't actually drive them
00:03:44 --> 00:03:46 directly but in command of the the
00:03:46 --> 00:03:48 rovers on Mars and the two active NASA
00:03:48 --> 00:03:51 ones at the moment are Curiosity and
00:03:51 --> 00:03:52 Perseverance.
00:03:52 --> 00:03:58 uh they adapt to a 20 to 24 hours 39
00:03:58 --> 00:04:01 minutes day uh and do it quite
00:04:02 --> 00:04:05 successfully as far as I've been able to
00:04:05 --> 00:04:06 work out.
00:04:06 --> 00:04:09 >> Well, I hope so.
00:04:09 --> 00:04:10 >> Yeah. Otherwise, there might be a pile
00:04:10 --> 00:04:13 up on Mars. Um, and in fact, the reason
00:04:13 --> 00:04:14 why I said they don't actually drive
00:04:14 --> 00:04:17 them is because the the rovers
00:04:17 --> 00:04:19 themselves have got to be to some extent
00:04:19 --> 00:04:22 autonomous because of the the the delay
00:04:22 --> 00:04:25 in in signal time to get between Mars
00:04:25 --> 00:04:28 and the Earth. You can't have video
00:04:28 --> 00:04:29 coming back from your rover and a
00:04:29 --> 00:04:31 steering wheel so that you respond to
00:04:31 --> 00:04:33 that because you'd have a sort of 20 or
00:04:33 --> 00:04:36 30 minute delay probably before
00:04:36 --> 00:04:39 >> uh before um you you turn before the
00:04:39 --> 00:04:41 wheels turned on on the rover.
00:04:41 --> 00:04:44 >> I would I would imagine that the the
00:04:44 --> 00:04:48 manual driving of a rover from Earth on
00:04:48 --> 00:04:50 Mars would be damn near impossible
00:04:50 --> 00:04:52 because even your images would be out of
00:04:52 --> 00:04:53 sync with
00:04:53 --> 00:04:54 >> everything's out of sync. That's right.
00:04:54 --> 00:04:56 So you see, oh, there's a rock coming
00:04:56 --> 00:04:58 up. That was 40 minutes ago.
00:04:58 --> 00:05:01 >> I'll turn left now.
00:05:01 --> 00:05:03 >> Oops.
00:05:03 --> 00:05:08 >> Yeah. Um so so the the rovers drive
00:05:08 --> 00:05:12 themselves basically uh with a lot of um
00:05:12 --> 00:05:15 assistance and monitoring from Earth uh
00:05:15 --> 00:05:18 in order to see what's coming up and see
00:05:18 --> 00:05:21 what the onboard computers are doing in
00:05:21 --> 00:05:23 terms of what route they're taking
00:05:23 --> 00:05:26 through the rocks and debris on Mars.
00:05:26 --> 00:05:29 uh and um so but those people as I
00:05:29 --> 00:05:32 understand it do go on to uh this 24
00:05:32 --> 00:05:36 hours and 39 minutes day length uh I
00:05:36 --> 00:05:38 think it's near enough to our 24 hours
00:05:38 --> 00:05:39 that I think they adapt quite quickly
00:05:39 --> 00:05:41 from my recollection of our previous
00:05:42 --> 00:05:44 conversation about this Andrew
00:05:44 --> 00:05:47 >> yeah I if I remember rightly we were
00:05:47 --> 00:05:48 talking about the fact that if you're
00:05:48 --> 00:05:51 going to stay on Mars long term you
00:05:51 --> 00:05:55 would have to adapt
00:05:55 --> 00:05:59 um you wouldn't adapt naturally
00:05:59 --> 00:06:01 at all. You you'd have to take catnaps
00:06:01 --> 00:06:05 or something like that to to catch up um
00:06:05 --> 00:06:08 or something to that effect.
00:06:08 --> 00:06:11 >> Well, it Yes. So, your circadian rhythms
00:06:11 --> 00:06:12 would they'd be under stress. They
00:06:12 --> 00:06:14 they'd change.
00:06:14 --> 00:06:17 >> Um um and I suppose you'd have a
00:06:17 --> 00:06:19 permanent feeling of jet lag probably.
00:06:19 --> 00:06:21 Probably what it feels like.
00:06:21 --> 00:06:23 >> It would be tough. I read an article uh
00:06:23 --> 00:06:26 last weekend which I I found fascinating
00:06:26 --> 00:06:30 and it was um detailing how the 8hour
00:06:30 --> 00:06:33 night cycle that humans have like going
00:06:33 --> 00:06:36 to bed for 8 hours is a myth.
00:06:36 --> 00:06:37 >> Yes.
00:06:37 --> 00:06:40 >> And that um it was it was actually
00:06:40 --> 00:06:42 something invented by a mattress company
00:06:42 --> 00:06:45 back in 1938. Have you heard this?
00:06:45 --> 00:06:46 >> No. Yes.
00:06:46 --> 00:06:49 >> I I I do know that we used to sleep
00:06:49 --> 00:06:50 twice in the night with it.
00:06:50 --> 00:06:52 >> That's right. So, you go to bed at like
00:06:52 --> 00:06:54 9:00
00:06:54 --> 00:06:56 >> and you'd sleep for 4 hours and then
00:06:56 --> 00:06:58 you'd get up for 2 hours and you'd do
00:06:58 --> 00:06:59 stuff
00:06:59 --> 00:07:01 >> like stuff we can't talk about on this
00:07:01 --> 00:07:04 podcast, but other stuff like um
00:07:04 --> 00:07:08 >> they cited a couple of um famous people
00:07:08 --> 00:07:10 um whose names have dropped straight out
00:07:10 --> 00:07:14 of my head. Um, William Shakespeare
00:07:14 --> 00:07:17 >> uh apparently wrote a lot of his famous
00:07:17 --> 00:07:20 works between 1 and 3 in the morning
00:07:20 --> 00:07:22 when he got up and then he go back to
00:07:22 --> 00:07:25 bed for 4 hours. And Bethovven did the
00:07:26 --> 00:07:27 same thing with some of his symphonies.
00:07:27 --> 00:07:30 He wrote some of the best works that he
00:07:30 --> 00:07:35 ever created at 3:00 in the morning um
00:07:35 --> 00:07:37 during his wake time between his two
00:07:37 --> 00:07:41 sleeps. Yeah. So the 8hour sleep
00:07:41 --> 00:07:44 that we have at night was an invention
00:07:44 --> 00:07:46 apparently to sell mattresses.
00:07:46 --> 00:07:48 That's what I'm told. I look I haven't
00:07:48 --> 00:07:52 confirmed or denied that but it seems it
00:07:52 --> 00:07:55 seems possible I suppose. Well, yes. I I
00:07:55 --> 00:08:00 think I think we have we've I think um
00:08:00 --> 00:08:02 there's been evidence from, you know,
00:08:02 --> 00:08:04 the earliest times,
00:08:04 --> 00:08:06 uh the times when people truly were
00:08:06 --> 00:08:08 ancient peoples back thousands of years
00:08:08 --> 00:08:10 ago, uh that that's how they lived their
00:08:10 --> 00:08:12 lives, exactly as you've said. And maybe
00:08:12 --> 00:08:14 there were the last vestigages of that
00:08:14 --> 00:08:15 were
00:08:15 --> 00:08:17 >> keeping going in Shakespeare's time and
00:08:17 --> 00:08:20 then in Beethoven's time. Um
00:08:20 --> 00:08:22 there weren't that many clocks around
00:08:22 --> 00:08:23 then. There were some, but not that
00:08:23 --> 00:08:25 many. It wasn't like you had a
00:08:26 --> 00:08:27 smartwatch by your bedside or anything
00:08:28 --> 00:08:30 like that. So, uh it would be a natural
00:08:30 --> 00:08:34 rhythm that they would use uh to, you
00:08:34 --> 00:08:36 know, to to sleep and wake up.
00:08:36 --> 00:08:37 >> Yes. And if you're natural,
00:08:37 --> 00:08:39 modernization certainly messed us up,
00:08:39 --> 00:08:40 hasn't it?
00:08:40 --> 00:08:41 >> Yeah. Yeah, that's right. I think in
00:08:41 --> 00:08:42 that case it has.
00:08:42 --> 00:08:45 >> And I think uh on Mars it will be um it
00:08:45 --> 00:08:48 will be a pretty difficult thing. I I
00:08:48 --> 00:08:48 imagine
00:08:48 --> 00:08:51 >> it may be. So, um maybe I can just
00:08:51 --> 00:08:54 sidestep here slightly, Andrew, because
00:08:54 --> 00:08:58 um I would very much like to know uh
00:08:58 --> 00:09:00 what answer one of our listeners would
00:09:00 --> 00:09:02 give to that. And that's Dr. Heidi
00:09:02 --> 00:09:05 Deblock, who's I think based in Houston,
00:09:05 --> 00:09:07 if I remember rightly, who is a
00:09:07 --> 00:09:11 basically a space medic. Uh and um it
00:09:11 --> 00:09:13 will be very interesting to hear her
00:09:13 --> 00:09:16 take on how humans will adapt to that.
00:09:16 --> 00:09:18 And if I may, she was in touch with us
00:09:18 --> 00:09:20 recently to comment on one of our
00:09:20 --> 00:09:22 earlier questions. Would it be all right
00:09:22 --> 00:09:23 if I read that?
00:09:23 --> 00:09:25 >> And that was when we were talking about
00:09:25 --> 00:09:28 how people deal with um gravity when
00:09:28 --> 00:09:30 they get back on Earth after being out
00:09:30 --> 00:09:31 in space for a while.
00:09:31 --> 00:09:33 >> Correct. Yes, that's right.
00:09:33 --> 00:09:37 >> Uh she says, um, "I just finished the
00:09:37 --> 00:09:40 July 5th Space Nuts and wanted to help
00:09:40 --> 00:09:41 answer the question about how the
00:09:41 --> 00:09:43 astronauts feel when they land back on
00:09:43 --> 00:09:45 Earth. Of course, I haven't experienced
00:09:45 --> 00:09:47 it in person, but have worked with
00:09:47 --> 00:09:49 plenty of astronauts at landing in
00:09:49 --> 00:09:51 particular. All of our physiology
00:09:51 --> 00:09:54 changes in space as we are designed for
00:09:54 --> 00:09:57 1G. Some astronauts are pretty good when
00:09:57 --> 00:09:58 they land, especially those who are on
00:09:58 --> 00:10:01 the shuttle and in space for short time
00:10:01 --> 00:10:04 for a sorry a 4A short time. Some had
00:10:04 --> 00:10:07 significant problems. They stem from the
00:10:07 --> 00:10:10 orthostatic hypotension as a result from
00:10:10 --> 00:10:12 the cardiovascular changes. Some of the
00:10:12 --> 00:10:14 changes in the inner ear with balance
00:10:14 --> 00:10:16 and knowing where you physically are,
00:10:16 --> 00:10:19 some mild weaknesses, etc. These changes
00:10:20 --> 00:10:22 are more exaggerated with long duration
00:10:22 --> 00:10:23 flight in the International Space
00:10:23 --> 00:10:26 Station. The vision problems are called
00:10:26 --> 00:10:30 SANS, SNS, which is an acronym for
00:10:30 --> 00:10:33 spaceflight associated neuroccular
00:10:33 --> 00:10:36 syndrome. Our lab is studying that as
00:10:36 --> 00:10:38 well. That's a whole other fascinating
00:10:38 --> 00:10:40 issue.
00:10:40 --> 00:10:42 I could tell you some fun stories about
00:10:42 --> 00:10:44 astronauts and how weird some of them
00:10:44 --> 00:10:46 feel when they get back. Maybe we need
00:10:46 --> 00:10:47 to get Heidi on the show.
00:10:48 --> 00:10:49 >> Maybe we do.
00:10:49 --> 00:10:52 >> Yeah. No, that's um that's uh she has
00:10:52 --> 00:10:54 another interesting comment actually
00:10:54 --> 00:10:57 about the uh about the uh Voyager Golden
00:10:57 --> 00:10:59 Record, but we might talk about that
00:10:59 --> 00:11:00 another time.
00:11:00 --> 00:11:01 >> Fair enough. Yeah. All right. Thank you,
00:11:01 --> 00:11:03 Heidi. That was fascinating. Yeah. Um
00:11:04 --> 00:11:05 what a what an amazing job working with
00:11:06 --> 00:11:08 all those incredible people
00:11:08 --> 00:11:10 trying to figure out how to deal with
00:11:10 --> 00:11:13 the zerog problem. But uh on Mars the
00:11:13 --> 00:11:15 gravity will also be an issue. So um
00:11:16 --> 00:11:17 there's there's a heck of a lot that
00:11:17 --> 00:11:21 needs to be sorted out before we um
00:11:21 --> 00:11:24 >> put people down there because it it it's
00:11:24 --> 00:11:25 so such a long trip to get there. It's
00:11:25 --> 00:11:27 not like you can go ah no this is no
00:11:27 --> 00:11:28 good and come straight back. It's not
00:11:28 --> 00:11:30 going to be that simple.
00:11:30 --> 00:11:31 >> No, that's right. Once you're on your
00:11:31 --> 00:11:33 way, you're on your way. And the only
00:11:33 --> 00:11:35 way back is to keep going.
00:11:35 --> 00:11:37 >> Yeah, exactly. Thanks for the question,
00:11:37 --> 00:11:40 John. Uh, well asked. And, uh, yeah,
00:11:40 --> 00:11:42 it's not going to be a snack, that's for
00:11:42 --> 00:11:44 sure. Let's, uh, move on to our next
00:11:44 --> 00:11:48 question from Dan. Hello, gentlemen. Dan
00:11:48 --> 00:11:50 from the Gold Coast here. Uh, now, I
00:11:50 --> 00:11:53 know you've been asked a million
00:11:53 --> 00:11:56 questions about black holes. Uh, but I
00:11:56 --> 00:11:57 do have a quick two-parter, and I'm
00:11:58 --> 00:11:59 hoping it's something you've never had
00:11:59 --> 00:12:02 to answer before. really quickly from
00:12:02 --> 00:12:05 the point when a black hole is born,
00:12:05 --> 00:12:06 birth, created, whatever you want to
00:12:06 --> 00:12:09 call it. Uh how quickly is that growing
00:12:09 --> 00:12:11 to become a let's say super massive
00:12:11 --> 00:12:12 black hole or just something a lot
00:12:12 --> 00:12:16 bigger? Um or is that not how black
00:12:16 --> 00:12:18 holes work and I'm not understanding it
00:12:18 --> 00:12:22 properly? two, uh, hypothetically, if
00:12:22 --> 00:12:24 there's no matter or energy or anything
00:12:24 --> 00:12:28 surrounding the black hole to take in
00:12:28 --> 00:12:31 and let's say eat, uh, is the black hole
00:12:31 --> 00:12:33 still going to grow? Is there more to
00:12:33 --> 00:12:36 the black hole growing than I
00:12:36 --> 00:12:39 understand? Um, yeah, hopefully that
00:12:39 --> 00:12:40 made sense and hopefully it's worth
00:12:40 --> 00:12:43 answering. Love the show. Love you guys
00:12:43 --> 00:12:45 work. Cheers. Bye.
00:12:45 --> 00:12:47 >> Thank you, Dan. Uh, nice to hear from
00:12:47 --> 00:12:50 you. Uh yeah, a couple of questions in
00:12:50 --> 00:12:52 that one. Um we never talk about black
00:12:52 --> 00:12:55 holes, but we will today. Uh speed of
00:12:55 --> 00:12:59 growth. Um that's an interesting one. Uh
00:12:59 --> 00:13:01 given that we're starting to think that
00:13:01 --> 00:13:06 there were some absolutely enormous
00:13:06 --> 00:13:09 um black holes in the early universe.
00:13:09 --> 00:13:13 Um and and that they're looking for more
00:13:13 --> 00:13:14 and more evidence to see what was going
00:13:14 --> 00:13:17 on early on. Um, but we've got some
00:13:17 --> 00:13:21 gargantuan ones still around. Uh, so how
00:13:21 --> 00:13:24 fast did they get that big? And I I I'm
00:13:24 --> 00:13:26 starting to think, Fred, it wouldn't be
00:13:26 --> 00:13:28 a stock standard approach.
00:13:28 --> 00:13:31 Maybe not. Maybe not. Uh, but well, I
00:13:31 --> 00:13:34 mean, Dan's asking uh one of the
00:13:34 --> 00:13:35 fundamental questions of astrophysics at
00:13:35 --> 00:13:37 the moment. This is a very hot topic.
00:13:37 --> 00:13:39 Yeah. And what set the cat among the
00:13:39 --> 00:13:41 pigeons and made it a hot topic is the
00:13:41 --> 00:13:44 James Web Space Telescope because um
00:13:44 --> 00:13:48 until that came along, the idea was that
00:13:48 --> 00:13:51 as basically as Dan suggests, black
00:13:51 --> 00:13:54 holes were formed in the early universe
00:13:54 --> 00:13:58 by exploding stars that um collapsed at
00:13:58 --> 00:14:00 the end of their lives to to form a
00:14:00 --> 00:14:02 black hole. the core would collapse to a
00:14:02 --> 00:14:05 black hole and that then over over
00:14:05 --> 00:14:07 billions of years that black hole would
00:14:08 --> 00:14:10 grow and eventually in our own epoch
00:14:10 --> 00:14:13 today 13.8 billion years after the after
00:14:13 --> 00:14:16 the big bang uh you have super massive
00:14:16 --> 00:14:17 black holes at the center of every
00:14:18 --> 00:14:21 galaxy. That was the old wisdom. But the
00:14:21 --> 00:14:22 James Webb telescope has turned that
00:14:22 --> 00:14:25 completely on its head because we have
00:14:25 --> 00:14:28 serious evidence of super massive black
00:14:28 --> 00:14:32 holes within the first 500 million years
00:14:32 --> 00:14:34 of the universe's existence. And that's
00:14:34 --> 00:14:39 too quick for or too short a time for
00:14:39 --> 00:14:42 this um you know the this slow accretion
00:14:42 --> 00:14:46 of of stuff uh as being the um the the
00:14:46 --> 00:14:49 the growth mechanism for black holes. Uh
00:14:49 --> 00:14:50 it's too too short a time for that to be
00:14:50 --> 00:14:55 the case. Uh so either our ideas of how
00:14:55 --> 00:14:59 fast they gobble up matter is wrong and
00:14:59 --> 00:15:01 they gobble up faster matter a lot
00:15:01 --> 00:15:02 faster than we thought. And we actually
00:15:02 --> 00:15:05 covered a story on this I think about
00:15:05 --> 00:15:07 four or five episodes ago because there
00:15:07 --> 00:15:10 are some scientists who came to
00:15:10 --> 00:15:11 conclusion that one of the things that
00:15:12 --> 00:15:15 we thought limited how fast a black hole
00:15:15 --> 00:15:17 can gobble stuff up uh was actually
00:15:17 --> 00:15:20 invalid under certain circumstances.
00:15:20 --> 00:15:23 >> So that's that's one avenue of research
00:15:23 --> 00:15:26 that's come from the James Web telescope
00:15:26 --> 00:15:28 showing us that we've got these super
00:15:28 --> 00:15:29 massive black holes in the early
00:15:29 --> 00:15:31 universe. But the other one is the the
00:15:31 --> 00:15:33 idea of the little pink dots or the
00:15:33 --> 00:15:35 little red dots as they're called. And
00:15:36 --> 00:15:39 these are thought to be basically just
00:15:39 --> 00:15:43 clouds of gas, hydrogen gas, which are
00:15:43 --> 00:15:46 directly feeding a black hole that may
00:15:46 --> 00:15:48 have been formed in the Big Bang. In
00:15:48 --> 00:15:49 other words, you didn't have to have
00:15:49 --> 00:15:52 star formation and then stars blowing up
00:15:52 --> 00:15:55 to create back black holes in order to
00:15:55 --> 00:15:57 kick this process off. the big bang
00:15:57 --> 00:15:59 itself might have kicked off the process
00:15:59 --> 00:16:00 of black hole formation by producing
00:16:00 --> 00:16:03 these things that we call primordial
00:16:03 --> 00:16:07 black holes. Um and they may have turned
00:16:07 --> 00:16:10 out to be able to grow very quickly uh
00:16:10 --> 00:16:13 by immersing themselves simply in big
00:16:13 --> 00:16:15 clouds of hydrogen and gobbling it all
00:16:16 --> 00:16:16 up.
00:16:16 --> 00:16:20 >> Yeah. Of course uh when they run out of
00:16:20 --> 00:16:23 stuff they can't grow. Is that right?
00:16:23 --> 00:16:25 >> That's right. So, that's part two of
00:16:25 --> 00:16:28 Dan's question. Uh, what happens when
00:16:28 --> 00:16:29 there's nothing there for them to eat?
00:16:29 --> 00:16:31 And they become what we call quiescent
00:16:31 --> 00:16:33 black holes. They they they don't do
00:16:33 --> 00:16:36 anything. They're there. Uh, and they're
00:16:36 --> 00:16:39 still things that um if if a cloud of
00:16:39 --> 00:16:42 hydrogen strayed by, they they might
00:16:42 --> 00:16:44 seize it by their own gravity and pull
00:16:44 --> 00:16:45 it in. Yeah.
00:16:45 --> 00:16:47 >> But, um, they're not going to go out
00:16:47 --> 00:16:49 roaming through the um roaming through
00:16:49 --> 00:16:51 the universe looking for stuff to
00:16:52 --> 00:16:53 accrete. In other words, looking for a
00:16:53 --> 00:16:54 snap.
00:16:54 --> 00:16:56 >> Yeah. I used to work with a guy whose
00:16:56 --> 00:16:58 nickname was queercent black hole. He
00:16:58 --> 00:17:03 was there, but he didn't do anything.
00:17:03 --> 00:17:08 >> Yes, I think I know who you mean.
00:17:08 --> 00:17:11 Yeah. Anyway, quent black holes are
00:17:11 --> 00:17:13 basically what what Dan has described.
00:17:13 --> 00:17:15 But the first part of his question is
00:17:15 --> 00:17:17 absolutely asking the same questions
00:17:17 --> 00:17:20 that today's astrophysicists are. It's
00:17:20 --> 00:17:22 one whose answer we don't know. But the
00:17:22 --> 00:17:24 contentus will emerge over the next
00:17:24 --> 00:17:26 probably not very long because we're
00:17:26 --> 00:17:28 getting so much data from the James Webb
00:17:28 --> 00:17:29 telescope
00:17:29 --> 00:17:30 >> uh that I think it'll be quite soon
00:17:30 --> 00:17:32 before this whole issue is resolved.
00:17:32 --> 00:17:34 >> I would think sorry
00:17:34 --> 00:17:36 >> I was just going to say when when there
00:17:36 --> 00:17:38 is hard evidence of a primordial black
00:17:38 --> 00:17:40 hole being discovered, one that was
00:17:40 --> 00:17:43 created in the Big Bang, then that'll be
00:17:43 --> 00:17:45 Nobel Prizewinning science when we get
00:17:45 --> 00:17:47 to that stage.
00:17:47 --> 00:17:48 >> But it won't be us.
00:17:48 --> 00:17:50 >> Indeed. I was going to suggest that um
00:17:50 --> 00:17:53 black holes are probably like humans.
00:17:53 --> 00:17:54 Consumption will decide how big they
00:17:54 --> 00:17:56 get.
00:17:56 --> 00:17:57 >> Maybe that's right.
00:17:57 --> 00:17:58 >> Yeah. Yeah.
00:17:58 --> 00:18:01 >> We'll have to wait and see. All right,
00:18:01 --> 00:18:03 Dan. Uh hopefully we covered that for
00:18:03 --> 00:18:05 you adequately. Thanks for sending in
00:18:05 --> 00:18:07 the question. This is Space Nuts with
00:18:07 --> 00:18:12 Andrew Dunley and Professor Fred Watson.
00:18:12 --> 00:18:15 >> Three, two, one.
00:18:15 --> 00:18:18 >> Space nuts. Our next question, Fred,
00:18:18 --> 00:18:21 comes from Thomas Reed. Thomas is 11
00:18:21 --> 00:18:23 years old. He says, "Something has been
00:18:23 --> 00:18:25 troubling me in books I've read. They
00:18:25 --> 00:18:28 say that the centers of galaxies are
00:18:28 --> 00:18:30 very big black holes, and I have a few
00:18:30 --> 00:18:32 questions about them, but I'm only an
00:18:32 --> 00:18:35 11year-old kid, so the questions might
00:18:35 --> 00:18:36 sound silly, but here they are. Now, we
00:18:36 --> 00:18:38 got five questions, Fred, so we can be
00:18:38 --> 00:18:41 brief on them on them, unless you want
00:18:41 --> 00:18:43 to sit here another couple of hours. Um,
00:18:43 --> 00:18:45 if Jy was here, we would be a couple of
00:18:45 --> 00:18:46 hours.
00:18:46 --> 00:18:49 Um, can the galactic centers swallow all
00:18:49 --> 00:18:51 the stars and planets in the galaxy? How
00:18:51 --> 00:18:54 big are the galactic centers or do we
00:18:54 --> 00:18:56 not know? Uh, if they can swallow up all
00:18:56 --> 00:18:59 the stars and planets, is there a limit?
00:18:59 --> 00:19:01 If there is a limit, what is it? And if
00:19:02 --> 00:19:04 there is a limit, what happens when the
00:19:04 --> 00:19:06 limit is reached? Thank you for taking
00:19:06 --> 00:19:08 the time to read this. And I would love
00:19:08 --> 00:19:09 it if you could reply. Well, we are
00:19:10 --> 00:19:13 going to reply right now, Thomas. Um,
00:19:13 --> 00:19:15 yeah, it's uh it's great that uh
00:19:15 --> 00:19:18 somebody so young is is taking a keen
00:19:18 --> 00:19:20 interest in something so mysterious as a
00:19:20 --> 00:19:23 as a black hole. Uh we want to start at
00:19:23 --> 00:19:25 the top. Can the galactic center swallow
00:19:25 --> 00:19:27 all the stars and planets in the galaxy?
00:19:27 --> 00:19:30 >> Well, so the answer is no. Um so the
00:19:30 --> 00:19:32 galaxies are very big. Um ours is about
00:19:32 --> 00:19:35 100 light years across. Uh, black
00:19:35 --> 00:19:38 holes have a a kind of sphere of
00:19:38 --> 00:19:41 influence um, which gravitationally
00:19:41 --> 00:19:43 stretches to the edge of the galaxy, but
00:19:43 --> 00:19:45 by the time you get there, the gravity
00:19:45 --> 00:19:47 of the black hole is very very weak
00:19:47 --> 00:19:50 indeed. Uh, and so it's only in the
00:19:50 --> 00:19:53 central region of a galaxy where you
00:19:53 --> 00:19:55 could get material being swallowed up
00:19:55 --> 00:19:58 uh, to create this activity that we talk
00:19:58 --> 00:19:59 about when we talk about active black
00:19:59 --> 00:20:03 holes. uh where there's uh an accretion
00:20:03 --> 00:20:05 disc, a disc of material swirling around
00:20:05 --> 00:20:08 it and these jets that point basically
00:20:08 --> 00:20:09 at right angles to the accretion disc.
00:20:09 --> 00:20:11 Jets of material traveling at nearly the
00:20:11 --> 00:20:13 speed of light. Quite extraordinary.
00:20:13 --> 00:20:16 >> So, um that's all great and a black hole
00:20:16 --> 00:20:18 is like a factory or a furnace doing
00:20:18 --> 00:20:20 that, but it's it stretch is not very
00:20:20 --> 00:20:24 far. Uh it's measured in light years,
00:20:24 --> 00:20:25 but not in hundreds of thousands of
00:20:25 --> 00:20:27 light years, which you'd have to be to
00:20:27 --> 00:20:29 to grab everything in the galaxy. So the
00:20:29 --> 00:20:32 answer is no. Uh the galactic center
00:20:32 --> 00:20:34 black hole cannot swallow all the stars
00:20:34 --> 00:20:36 and planets in the galaxy.
00:20:36 --> 00:20:39 >> So So Thomas can sleep well tonight. Um
00:20:39 --> 00:20:41 how big are the galactic centers? Do we
00:20:41 --> 00:20:43 know how big?
00:20:43 --> 00:20:47 >> We do. Yes, we do because we can measure
00:20:47 --> 00:20:50 we can measure the uh the speed of
00:20:50 --> 00:20:54 rotation of stuff swirling around a
00:20:54 --> 00:20:56 black hole if it's an active one.
00:20:56 --> 00:20:58 >> Yeah. And that directly tells you the
00:20:58 --> 00:21:01 mass of the black hole. Um because the
00:21:01 --> 00:21:03 bigger the black hole the faster the
00:21:03 --> 00:21:07 stuff is going. And so um in terms of
00:21:07 --> 00:21:10 you know if the if if by big Thomas
00:21:10 --> 00:21:13 means what's their mass uh we can we can
00:21:13 --> 00:21:16 measure them quite accurately. Now
00:21:16 --> 00:21:18 because we can measure their mass we can
00:21:18 --> 00:21:20 also work out their event horizon
00:21:20 --> 00:21:24 diameter or radius. The event horizon is
00:21:24 --> 00:21:26 that sort of imaginary sphere around a
00:21:26 --> 00:21:29 black hole beyond which light cannot
00:21:29 --> 00:21:32 escape and so it would appear as a dark
00:21:32 --> 00:21:35 sphere. Um so the event horizon is the
00:21:35 --> 00:21:36 point of no return for anything going
00:21:36 --> 00:21:39 into a black hole and it's also the
00:21:39 --> 00:21:42 point of no escape for for light waves.
00:21:42 --> 00:21:45 Uh so we can knowing the mass of a black
00:21:45 --> 00:21:48 hole we can calculate how big that event
00:21:48 --> 00:21:50 horizon would be. And some of the super
00:21:50 --> 00:21:52 massive ones are really very big.
00:21:52 --> 00:21:55 They're measured in light years, tens of
00:21:55 --> 00:21:56 light years perhaps for the super
00:21:56 --> 00:21:57 massive black holes.
00:21:57 --> 00:22:00 >> Yeah, that it's it's a level of enormity
00:22:00 --> 00:22:01 that you just struggle to get your head
00:22:02 --> 00:22:02 around.
00:22:02 --> 00:22:04 >> Yeah. I suppose in terms of the rest of
00:22:04 --> 00:22:06 Thomas's questions, you've basically
00:22:06 --> 00:22:08 answered it with the answer to the first
00:22:08 --> 00:22:10 question cuz he's asking if they can
00:22:10 --> 00:22:12 swallow all the stars and planets. Is
00:22:12 --> 00:22:14 there a limit? If there is a limit, what
00:22:14 --> 00:22:17 is it? Uh and if there is a limit, what
00:22:17 --> 00:22:19 happens when the limit is reached? Well,
00:22:19 --> 00:22:23 the limit is probably the local area of
00:22:23 --> 00:22:25 the center of the galaxy and what's
00:22:25 --> 00:22:27 available to eat.
00:22:27 --> 00:22:28 >> Yes, that's right. So the the limit the
00:22:28 --> 00:22:33 limiting factor is um basically the the
00:22:33 --> 00:22:35 what you might call the grasp of the
00:22:35 --> 00:22:37 black hole. How how far it can reach to
00:22:37 --> 00:22:40 pull something in. And that is dependent
00:22:40 --> 00:22:43 on how fast the objects are moving. So
00:22:43 --> 00:22:45 you can have some stars and there are
00:22:45 --> 00:22:47 some we've observed them uh with
00:22:47 --> 00:22:50 infrared radiation that are comfortably
00:22:50 --> 00:22:54 in orbit uh around the the black hole at
00:22:54 --> 00:22:56 the center of our own galaxy which are
00:22:56 --> 00:22:58 not being pulled in. They're orbiting
00:22:58 --> 00:23:00 and that's because their speed is enough
00:23:00 --> 00:23:02 to keep them out of the out of the grasp
00:23:02 --> 00:23:05 of the black hole. um their distances
00:23:05 --> 00:23:07 from the black hole are measured, you
00:23:07 --> 00:23:09 know, in not two dissimilar units from
00:23:09 --> 00:23:11 the from the solar system, sort of half
00:23:11 --> 00:23:14 a light day or something like that, you
00:23:14 --> 00:23:17 know, light light day. That's that's the
00:23:17 --> 00:23:18 sort of measures that we're talking
00:23:18 --> 00:23:19 about.
00:23:19 --> 00:23:22 >> Um which probably denies what I just
00:23:22 --> 00:23:25 said a few minutes ago about um some
00:23:25 --> 00:23:27 black hole event horizons being tens of
00:23:27 --> 00:23:29 light years. I don't think they are. I
00:23:29 --> 00:23:30 think they're smaller than that.
00:23:30 --> 00:23:32 >> Okay. I've thought of a way to explain
00:23:32 --> 00:23:34 it to Thomas. say, "Uh, Thomas, you've
00:23:34 --> 00:23:37 won a competition and you can go to
00:23:37 --> 00:23:40 McDonald's and eat everything you want."
00:23:40 --> 00:23:43 Absolutely. Just keep eating until you
00:23:43 --> 00:23:45 know the cows come home. However, you
00:23:45 --> 00:23:47 aren't allowed to move from wherever
00:23:47 --> 00:23:49 you're standing and you can only eat
00:23:49 --> 00:23:52 what's within reach.
00:23:52 --> 00:23:54 Once you run out of food, you stop
00:23:54 --> 00:23:57 growing. And you're the black hole, by
00:23:57 --> 00:23:59 the way. How's that for an analogy?
00:23:59 --> 00:24:00 >> It's a nice one. I like it.
00:24:00 --> 00:24:03 >> Yes. Yeah. Because the your reach is the
00:24:03 --> 00:24:04 sort of gravitational
00:24:04 --> 00:24:04 >> Yeah.
00:24:04 --> 00:24:06 >> force that you can exert. Yeah, it's a
00:24:06 --> 00:24:07 good way of putting it, Andrew. Well
00:24:07 --> 00:24:08 done. You should be on the reach.
00:24:08 --> 00:24:11 >> I try to think on 11y old level, but I'm
00:24:11 --> 00:24:12 I'm thinking Thomas was probably much
00:24:12 --> 00:24:15 brighter at 11 than I was.
00:24:15 --> 00:24:17 >> Struggle to get to 11. So do I.
00:24:17 --> 00:24:19 >> Yes. Thanks, Thomas. That was really
00:24:20 --> 00:24:21 terrific. Thanks for sending it in. And
00:24:21 --> 00:24:25 uh keep on listening.
00:24:25 --> 00:24:27 >> Swiftity
00:24:27 --> 00:24:30 base here. The angle has landed. Space
00:24:30 --> 00:24:31 Nuts.
00:24:31 --> 00:24:35 >> Final question, Fred, comes from Paul.
00:24:35 --> 00:24:37 Hello, Space Nuts. Paul here from sunny
00:24:37 --> 00:24:38 Bris Vegas, where it's currently
00:24:38 --> 00:24:40 bucketing down in what is being
00:24:40 --> 00:24:45 described as a rare rain occurrence.
00:24:45 --> 00:24:47 Anyway,
00:24:47 --> 00:24:50 I am currently looking through a very
00:24:50 --> 00:24:53 old book of mine. Guess it's old
00:24:53 --> 00:24:56 compared to the students I teach. It was
00:24:56 --> 00:24:58 published back in 1978. I think I got in
00:24:58 --> 00:25:01 in 1980 from uh an uncle of mine, Uncle
00:25:01 --> 00:25:03 Jim. Thank you very much. It's called
00:25:03 --> 00:25:05 Stars and Planets, and it's probably
00:25:05 --> 00:25:09 what got me into the whole field of
00:25:09 --> 00:25:11 astronomy in the first place, at least
00:25:11 --> 00:25:16 my interest in astronomy, obviously. Uh
00:25:16 --> 00:25:18 very very grateful. I'm on the page
00:25:18 --> 00:25:20 where it's talking about how the
00:25:20 --> 00:25:24 American astronomer Harlo Shepley
00:25:24 --> 00:25:28 used the 1.5 m reflector on top of Mount
00:25:28 --> 00:25:31 Wilson in California
00:25:31 --> 00:25:35 to work out that our sun is not at the
00:25:35 --> 00:25:37 center of our galaxy as was previously
00:25:37 --> 00:25:39 thought, but is about 2/3 of the way to
00:25:40 --> 00:25:43 the edge. Could you please give us some
00:25:43 --> 00:25:48 idea how he actually managed to do that?
00:25:48 --> 00:25:52 Was it something about the density of
00:25:52 --> 00:25:55 stars? I mean, how many stars in the
00:25:55 --> 00:25:57 field of view uh when you point it one
00:25:57 --> 00:25:59 way compared to the other? How did he do
00:25:59 --> 00:26:01 it? I'm really curious. And I know I
00:26:01 --> 00:26:03 could Google it, but I'd rather hear it
00:26:03 --> 00:26:07 from you guys. So, thanks in advance.
00:26:07 --> 00:26:10 love the show and dare I say, keep up
00:26:10 --> 00:26:13 the good work. Cheers.
00:26:13 --> 00:26:15 >> Cheers, Paul. Thanks for sending that
00:26:15 --> 00:26:18 in, uh, sending the question in and, uh,
00:26:18 --> 00:26:21 we don't know the answer. So,
00:26:21 --> 00:26:24 but we're going to Google it. No. Um,
00:26:24 --> 00:26:28 1978, Stars and Planets. Uh, I tried to
00:26:28 --> 00:26:30 look it up. There are teen books named
00:26:30 --> 00:26:31 Stars and Planets.
00:26:31 --> 00:26:32 >> Yeah.
00:26:32 --> 00:26:34 >> So, I haven't been able to, you know,
00:26:34 --> 00:26:36 distinguish one from the other as yet.
00:26:36 --> 00:26:39 So um uh yeah, you'll have to do some
00:26:39 --> 00:26:41 fishing to find the book that Paul was
00:26:41 --> 00:26:44 talking about. But he wanted to know
00:26:44 --> 00:26:48 about the man who decided or discovered
00:26:48 --> 00:26:50 that the sun was not the center of
00:26:50 --> 00:26:53 everything. Uh which was a common belief
00:26:54 --> 00:26:55 back in the day.
00:26:55 --> 00:26:58 >> It was um it was actually 1919 when that
00:26:58 --> 00:26:59 discovery was made. Um
00:26:59 --> 00:27:01 >> is it was it that recent?
00:27:01 --> 00:27:04 >> Yeah. Um I I it's one of my favorite
00:27:04 --> 00:27:06 astronomical discoveries, which is why I
00:27:06 --> 00:27:07 didn't need to go to Google to look it
00:27:07 --> 00:27:11 up. Um so it goes back to the time of
00:27:12 --> 00:27:16 William Hershel, uh who was a
00:27:16 --> 00:27:19 German turned British astronomer,
00:27:19 --> 00:27:22 worked late in the 18th century and
00:27:22 --> 00:27:23 early in the 19th century. He discovered
00:27:23 --> 00:27:26 the planet Uranus in 1781.
00:27:26 --> 00:27:28 But what he was doing when he discovered
00:27:28 --> 00:27:30 Uranus was actually mapping the Milky
00:27:30 --> 00:27:34 Way. He was observing uh the the Milky
00:27:34 --> 00:27:36 Way in a very systematic way with a
00:27:36 --> 00:27:39 relatively small telescope. So he sort
00:27:39 --> 00:27:42 of counting stars in the field of view
00:27:42 --> 00:27:44 of his telescope and then moving the
00:27:44 --> 00:27:46 telescope a bit further along the Milky
00:27:46 --> 00:27:48 Way. Counting stars again, how many he
00:27:48 --> 00:27:51 could see in the field of view and doing
00:27:51 --> 00:27:52 that and doing it. He couldn't do it all
00:27:52 --> 00:27:54 the way around the Milky Way because
00:27:54 --> 00:27:55 there's parts of it that he he could
00:27:55 --> 00:27:56 never see because they're in the
00:27:56 --> 00:27:58 southern hemisphere. But he got round
00:27:58 --> 00:28:01 most of it. And what he discovered was
00:28:01 --> 00:28:04 that the star counts are pretty even all
00:28:04 --> 00:28:06 the way around.
00:28:06 --> 00:28:09 >> And so that led him to build the
00:28:09 --> 00:28:12 hypothesis that the stars are in a sort
00:28:12 --> 00:28:15 of flattened disc, which is correct, uh,
00:28:15 --> 00:28:17 but that we're very near the middle,
00:28:17 --> 00:28:20 which is not correct. And the reason why
00:28:20 --> 00:28:23 he got that erroneous answer was that
00:28:23 --> 00:28:25 when you look through a I think it was a
00:28:25 --> 00:28:28 7-in telescope if I remember rightly a
00:28:28 --> 00:28:30 telescope of that size at the Milky Way,
00:28:30 --> 00:28:33 the stars that you see are all
00:28:33 --> 00:28:36 relatively nearby. They're perhaps a
00:28:36 --> 00:28:38 thousand light years away or something
00:28:38 --> 00:28:40 like that, maybe a bit more, maybe a
00:28:40 --> 00:28:42 couple of thousand light years away in
00:28:42 --> 00:28:44 the plane of the Milky Way. And that's
00:28:44 --> 00:28:46 partly because the Milky Way is very
00:28:46 --> 00:28:48 dusty. Uh there's a lot of dust
00:28:48 --> 00:28:50 everywhere. It's probably better
00:28:50 --> 00:28:52 described as smoke, but we call it dust
00:28:52 --> 00:28:54 in the world of astronomy. And so that
00:28:54 --> 00:28:57 dust limits how far you can see. And so
00:28:57 --> 00:28:59 when you look at the Milky Way, it does
00:28:59 --> 00:29:01 look generally relatively even. There's
00:29:01 --> 00:29:03 one bit in the constellation of
00:29:03 --> 00:29:05 Sagittarius where it's it's brighter and
00:29:05 --> 00:29:07 that's because you are looking towards
00:29:07 --> 00:29:09 as we now know the galactic center. But
00:29:09 --> 00:29:12 um Hershel um he couldn't see that very
00:29:12 --> 00:29:13 well from the northern hemisphere
00:29:14 --> 00:29:16 anyway. But he did sort of discount that
00:29:16 --> 00:29:19 uh he said by and large it's the same
00:29:20 --> 00:29:21 count all the way around. So we must be
00:29:21 --> 00:29:25 in the middle. Uh roll on the the years
00:29:25 --> 00:29:28 and in 1919 Harlo Shappley a very gifted
00:29:28 --> 00:29:30 American astronomer although he did get
00:29:30 --> 00:29:33 one thing one big thing wrong. Uh but
00:29:33 --> 00:29:36 what he did was he was interested in
00:29:36 --> 00:29:38 objects that we call globular clusters.
00:29:38 --> 00:29:40 And so these are in fact they were named
00:29:40 --> 00:29:42 by William Hershel. He gave them that
00:29:42 --> 00:29:44 name clusters of stars that appear like
00:29:44 --> 00:29:49 a globe. Uh and uh her halos Shappley
00:29:49 --> 00:29:52 was uh obser he like he was interested
00:29:52 --> 00:29:54 in globular clusters. He noticed there
00:29:54 --> 00:29:59 were a lot of them in our skies. Uh they
00:29:59 --> 00:30:02 tended to be different sizes.
00:30:02 --> 00:30:04 Uh and he didn't know whether that was
00:30:04 --> 00:30:06 cuz they were all the same size and some
00:30:06 --> 00:30:08 were nearer than others or whether they
00:30:08 --> 00:30:10 were intrinsically different sizes. But
00:30:10 --> 00:30:12 what he did notice was that there's a
00:30:12 --> 00:30:15 concentration of them in the southern
00:30:16 --> 00:30:19 hemisphere sky. Uh he was observing from
00:30:19 --> 00:30:21 California, so he could see a fair swath
00:30:21 --> 00:30:23 of the southern hemisphere sky. But he
00:30:23 --> 00:30:26 he noticed that they were concentrated
00:30:26 --> 00:30:28 in that direction and that made him
00:30:28 --> 00:30:32 wonder if that was where the center of
00:30:32 --> 00:30:34 the galaxy lay rather than us being near
00:30:34 --> 00:30:38 the center. Uh but then his other step
00:30:38 --> 00:30:41 was that he recognized that within these
00:30:41 --> 00:30:43 globular clusters were something called
00:30:43 --> 00:30:46 clust they called them cluster variables
00:30:46 --> 00:30:49 stars that varied in a certain way on a
00:30:49 --> 00:30:52 with a periodicity of about a day. Uh
00:30:52 --> 00:30:55 today we call them rli variables and I
00:30:55 --> 00:30:56 actually started my astronomical
00:30:56 --> 00:30:58 research back in the 70s studying these
00:30:58 --> 00:31:03 things. uh rlari variables uh and they
00:31:03 --> 00:31:07 they are good because they've got a
00:31:07 --> 00:31:11 basically a known distance uh if you if
00:31:11 --> 00:31:13 you can see an RLI variable and identify
00:31:13 --> 00:31:16 it as one you know how intrinsically
00:31:16 --> 00:31:19 bright it is uh and then from that you
00:31:19 --> 00:31:21 can work out how far away it is. And so
00:31:21 --> 00:31:24 he found these variable stars in the
00:31:24 --> 00:31:27 globular clusters and recognized that he
00:31:27 --> 00:31:29 could draw a chart with the the globular
00:31:29 --> 00:31:32 clusters all at their correct distance
00:31:32 --> 00:31:34 on it, make a kind of three-dimensional
00:31:34 --> 00:31:37 map of the sky. And sure enough, um they
00:31:37 --> 00:31:40 concentrated around the galactic center
00:31:40 --> 00:31:43 around a point. Uh he actually got the
00:31:43 --> 00:31:45 answer wrong because his magnitude, his
00:31:45 --> 00:31:47 brightness that he had for the uh
00:31:47 --> 00:31:50 cluster variables was incorrect. uh and
00:31:50 --> 00:31:51 I can't remember what answer he got, but
00:31:52 --> 00:31:55 in modern parliament it's about 25
00:31:55 --> 00:31:58 light years. The cluster, the globular
00:31:58 --> 00:32:00 clusters themselves cluster around a
00:32:00 --> 00:32:03 point about 25 light years away,
00:32:03 --> 00:32:05 which is deeply hidden by the dust
00:32:05 --> 00:32:08 clouds in Sagittarius. So
00:32:08 --> 00:32:10 >> he figured out that that's where the
00:32:10 --> 00:32:12 center of the galaxy was. A brilliant
00:32:12 --> 00:32:14 piece of detective work. We know he was
00:32:14 --> 00:32:17 right. Uh what he was wrong about was uh
00:32:17 --> 00:32:21 he had a big discussion I think in 1923
00:32:21 --> 00:32:24 just before Hubble recognized that
00:32:24 --> 00:32:26 galaxies were big things a long way
00:32:26 --> 00:32:28 away. Uh Shappley was arguing that
00:32:28 --> 00:32:31 galaxies lie within our own Milky Way
00:32:31 --> 00:32:32 that they're small objects in our own
00:32:32 --> 00:32:36 Milky Way. And he was um arguing it was
00:32:36 --> 00:32:37 a public debate actually between
00:32:38 --> 00:32:40 Chappley and a guy called Hea Curtis. Uh
00:32:40 --> 00:32:42 Curtis had the answer right. He said
00:32:42 --> 00:32:44 they're big and a long way off. Uh
00:32:44 --> 00:32:46 Shappley said, "No, they're small and
00:32:46 --> 00:32:48 nearby." And it was very soon after that
00:32:48 --> 00:32:50 that Hubble produced that they're big
00:32:50 --> 00:32:52 and a long way proved that they're big
00:32:52 --> 00:32:53 and a long way off.
00:32:53 --> 00:32:54 >> Yeah.
00:32:54 --> 00:32:55 >> So Shappley was wrong in that, but he
00:32:55 --> 00:32:57 was right about the Galactic Center.
00:32:57 --> 00:33:00 Fantastic. Gee whiz. Um great question,
00:33:00 --> 00:33:04 Paul. And um yeah, if people are looking
00:33:04 --> 00:33:06 for that uh that book, Stars and
00:33:06 --> 00:33:09 Planets, uh it is out there. Uh, look,
00:33:09 --> 00:33:10 I've I've found a couple that were
00:33:10 --> 00:33:13 actually published around that time that
00:33:13 --> 00:33:15 Paul mentioned, but um not sure if
00:33:15 --> 00:33:17 they're the ones I I can't remember the
00:33:17 --> 00:33:19 author now um that he said, but
00:33:19 --> 00:33:20 >> I don't think he mentioned an author,
00:33:20 --> 00:33:21 did he?
00:33:21 --> 00:33:22 >> I thought he did, but uh No, he might
00:33:22 --> 00:33:25 have mentioned an uncle
00:33:25 --> 00:33:27 mention
00:33:27 --> 00:33:28 it.
00:33:28 --> 00:33:30 >> But um
00:33:30 --> 00:33:32 um so yeah, thanks Paul. Thanks for the
00:33:32 --> 00:33:34 the question. And um yeah, it's it's a
00:33:34 --> 00:33:37 fascinating um history in astronomy as
00:33:37 --> 00:33:39 we discover these things. I think one of
00:33:39 --> 00:33:40 my favorite
00:33:40 --> 00:33:43 >> moments I suppose in in astronomical
00:33:43 --> 00:33:45 history was when they discovered that
00:33:45 --> 00:33:48 our sun was a star.
00:33:48 --> 00:33:50 >> Yeah, that was a long long time ago.
00:33:50 --> 00:33:51 >> Yeah.
00:33:51 --> 00:33:53 >> But for a while there we didn't think of
00:33:54 --> 00:33:54 it like that.
00:33:54 --> 00:33:55 >> Thought it was something else. That's
00:33:55 --> 00:33:57 right. Something bit special.
00:33:57 --> 00:34:00 >> Yeah. Um, and and I I saw that on a BBC
00:34:00 --> 00:34:02 documentary many years ago, and I sat
00:34:02 --> 00:34:05 there and went, "Wow, I never thought
00:34:05 --> 00:34:07 about that cuz I've always known it to
00:34:07 --> 00:34:10 be a star, but for generations, they
00:34:10 --> 00:34:12 didn't."
00:34:12 --> 00:34:14 Quite quite intriguing. And why would
00:34:14 --> 00:34:16 you? It doesn't look like a star.
00:34:16 --> 00:34:20 >> That's That's right. Uh, it's uh it's
00:34:20 --> 00:34:24 clearly quite different from a star.
00:34:24 --> 00:34:25 >> Incredible. Thanks, Paul. Thanks for
00:34:25 --> 00:34:27 sending that in. And if you have a
00:34:27 --> 00:34:29 question for a thanks to all our
00:34:29 --> 00:34:31 senderiners, I've always wanted to say
00:34:31 --> 00:34:33 that uh for their questions. And if you
00:34:33 --> 00:34:34 would like to send a question, go to our
00:34:34 --> 00:34:37 website spaceenutspodcast.com
00:34:37 --> 00:34:39 or spacenuts.io
00:34:39 --> 00:34:42 and there's a little AMA tab at the top
00:34:42 --> 00:34:44 which stands for ask me anything. Not me
00:34:44 --> 00:34:48 personally, it's the royal me. And um
00:34:48 --> 00:34:50 just put your uh question in there. It
00:34:50 --> 00:34:52 can be text or audio. Don't forget to
00:34:52 --> 00:34:53 tell us who you are and where you're
00:34:53 --> 00:34:55 from and have a look around while you're
00:34:55 --> 00:34:57 there. Don't forget to leave a review at
00:34:57 --> 00:35:00 your favorite podcasting platform. We're
00:35:00 --> 00:35:02 all done. Thanks, Fred.
00:35:02 --> 00:35:05 >> A great pleasure, Andrew. We um we uh
00:35:05 --> 00:35:07 continue to get great questions from
00:35:07 --> 00:35:09 great listeners and long may it
00:35:09 --> 00:35:09 continue. Thank you.
00:35:10 --> 00:35:12 >> Yes, indeed. We we continue to solve and
00:35:12 --> 00:35:13 evolve.
00:35:13 --> 00:35:15 Um maybe not.
00:35:15 --> 00:35:18 >> I'm not evolving.
00:35:18 --> 00:35:20 >> When once you reach a certain certain
00:35:20 --> 00:35:22 age, evolving just is not part of the
00:35:22 --> 00:35:23 program.
00:35:23 --> 00:35:24 >> That's right.
00:35:24 --> 00:35:26 >> Yeah. Ask my mom in the internet. Uh,
00:35:26 --> 00:35:28 thanks Fred. We'll see you soon.
00:35:28 --> 00:35:29 >> Sounds great. Thanks.
00:35:29 --> 00:35:31 >> Professor Fred Watson, astronomer at
00:35:31 --> 00:35:32 large. And thanks to Hugh in the studio.
00:35:32 --> 00:35:35 He's just turned up. Um, we started 39
00:35:36 --> 00:35:38 minutes ago. And and um, Hugh set his
00:35:38 --> 00:35:41 clock to a Martian day. So that's why
00:35:41 --> 00:35:43 he's 39 minutes late. Boom. Boom. And
00:35:43 --> 00:35:45 from me, Andrew Dunley, thanks for your
00:35:45 --> 00:35:46 company. We'll see you on the next
00:35:46 --> 00:35:48 episode of Space Nuts. Bye-bye.
00:35:48 --> 00:35:51 >> Space Nuts. You've been listening to the
00:35:51 --> 00:35:54 Space Nuts podcast. Missing complete
00:35:54 --> 00:35:57 >> available at Apple Podcasts, Spotify,
00:35:57 --> 00:35:59 iHeart Radio, or your favorite podcast
00:35:59 --> 00:36:02 player. You can also stream on demand at
00:36:02 --> 00:36:05 bytes.com. This has been another quality
00:36:05 --> 00:36:09 podcast production from byes.com.