Nov. 10, 2022



We've got an episode that divides by five. So, it means it's all questions.
And we've got a range of questions today, which cover the whole universe, basically. Several about the moon, which is a great one because by chance today there is an eclipse...

We've got an episode that divides by five. So, it means it's all questions.
And we've got a range of questions today, which cover the whole universe, basically. Several about the moon, which is a great one because by chance today there is an eclipse of the moon.
But they range from that out to vertical particles in the universe and the origin of dark matter.

Astronomy, Science, Space, and Stuff.
Space Nuts Episode 330 with Professor Fred Watson & Andrew Dunkley

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[0:00] Hello, thanks for joining us on Space Nuts, the astronomy and space science podcast. My name is Andrew Dunkley and it's always good to have your company. Hope you're well. Coming up on this episode,
being a divisible by five episode, 330, it's all questions. We've got some text questions and some audio questions to go through. Three of them are focused on the moon, so and very different
questions they all are. We've also got a follow up to the Dart mission and a question about virtual matter and what of the future of ground based telescopes now that we're getting such great
technology out into the ether. We're going to tackle all of that today on Space Nuts.
And I couldn't do this without Professor Fred Watson astronomer at large. Hello Fred.

[1:09] I'm sure you could Andrew. You know, in fact, you might do a better job.

[1:16] I know. No, no. Well, it might be the science fiction show, but that's all right. That's what it would turn into. Well, we'd have to call the podcast BS by Andrew.
That would be it which is not what astronomy daily is all about that's that's certainly factual but it's not me creating the information I'm just passing it on which is what on.
Generally reasonably average at Yeah, how you been? I mean I've been away even though we've had episodes continuing We previously recorded a whole batch before I went away. So have you been the last few weeks?
Very well. Thank you, Andrew a few hiccups here and there few ups and downs been down in South Australia doing gigs down there and South coast of New South Wales doing gigs down there. It's been good fun
But and there's more to come actually we've got tremendous things happening at the end of this month, but it's been fine And I'm looking forward to hearing about your trip away.

[2:18] Yeah, I haven't got much time to talk about it today, but I did have a question because I discovered something. We went to Florence, so I saw a statue of Galileo there, which I took a photo of. But when we were in Monaco, I saw an observatory. Are you aware of that? Yes, it is the observatory in Nice. Yeah, it wouldn't be in Monaco, but I was in Monaco and I could see it on the top of the mountain.
That's right. Yeah. Yeah, I've never been. I have, like you've been on the train probably to Monaco, but I did have a colleague who worked there and she said it was a delightful place to work as he'd expect the observatory of Nice. It's a very vertical place.
It is. Yes, it is. I know per square meter, it's the most expensive real estate in the world, but I couldn't live there because you're going up and downstairs and lifts and travel laders and I mean, I don't know how they write a race formula ones there. There is no room to move. There were, last time I was there, they were just, I think they had the Grand Prix and they were dismantling all the stands and things. So you could sort of see how it all fitted into the city. But yeah, it was quite impressive.

[3:34] Yeah, it was. Anyway, it was a fantastic trip, but I'll tell you about it in a later episode. Sounds good. Anyway, we'll get back to my holiday some other time when we've got time to talk about it. But we've got an all questions episode today, Fred, and we're going to kick off with a question from Zach in Washington.

[3:55] Now, we've heard from Zach before, but he's following up the Dart mission.
Hello, Andrew and Fred love the podcast. This is Zach from Washington DC Watch the dart mission broadcast live thought it was amazing. The whole mission was great.

[4:10] Fantastic idea to save the planet. I know this mission was a proof of concept But wasn't the impact asteroid the smaller one?

[4:20] Too small in itself even to have hypothetically done any damage to earth like we would this mission would be sort of Extrapolated to larger celestial bodies that pose an impact.
So I'm just kind of wondering about the the value We we would probably in the future need to repeat this with a larger payload
Anyways, that's my question. Thank you. Hmm. Yeah, it makes a very valid point does Zach
No he doesn't. Because, Zach forgive me for that sounded very cheeky, but the bottom line is that demorphous the object that was moved and it was successfully moved by the spacecraft
is about 170 meters in diameter and that would do
almost continent-wide damage if it hit the earth it is a significant object poses a Significant risk if an object that size entered the earth's.
You know atmosphere and then hit the ground.

[5:27] The so when you think of it so the.

[5:31] The sort of size scales that We've got Historical records of or in the region of 50 meters the Tungusk event was probably an object 50 meters or so across that.
Devastated thousands of square kilometers of.

[5:48] Siberian forest had it been a city that would have been You know curtains for the city so 170 meters is definitely potentially hazardous and dangerous object and.

[6:01] It's that scale of objects that approximate size that is currently the The target of interest for all the various telescopes that are looking for these things so far We have found none of that size that would impact the earth within the next hundred years.

[6:18] But the you know the the potential for damage from one of those is significant So this this experiment was not just a proof of concept in the sense that
you know, can this be done for asteroid of any size? It actually is a great test of what we might need to do if one of these things turns up
We think we only know about 40% of those objects of that size that would cross the Earth's orbit Whereas when you look up to a kilometer or so, we think we've got most of them
Not all of them because there are some some within the Earth's orbit that are hard to find There was one turned up last week 20 22 AP 7 Which was hitting the headlines last week because this is an asteroid which won't actually hit the Earth.
But 1.5 kilometers in diameter.
It's the size that we think we're pretty well sure of that we've got most of them But because that one orbits within the Earth it is it is not.

[7:15] Yet It hasn't been found yet. We talked about that A month or so ago about I think there was an astronomer that came out and said look
We need to pay more attention to the Sun for those objects that are orbiting within
the orbit of the earth because there are risk as well because we're looking outwards at things coming in but there could be things on the inside coming out. And this and this is one of them I must say I saw the headline while I was on holidays pop up from the popular press saying planet killing asteroid discovered and then of course the next line said but it won't hit earth.
That's right it's it's orbit actually keeps it away from earth even though it the orbit does cross the earth orbit but the asteroids said it's 2022 a p seven it's in what's called a resonant orbit with the earth so.

[8:12] Every once once round for the earth is five times sorry every five times round for the earth is once round for the asteroid it's never in the same place but it is possible that down the track. Orbit's change if you've got gravitational interactions with things like Jupiter and that thing goes a long way out into the solar system on its sort of outer side.
But yeah it highlighted exactly what that astronomer said a car remember who said that that we really need to keep an eye on things inside the earth orbit the best way to do that is actually with the spacecraft orbiting. Somewhere probably at the first Lagrange point between earth and the sun which is a stable point looking back at the earth for these near earth objects tracking not too far from the earth from the earth within the earth orbit.
Yeah the sun is a rather pesky thing isn't it just it's so bright it blinds us from seeing some of the threats to earth that may exist. And therein lies the problem but there are ways of getting past that surely with radar and you know things of that sort that's right.
You tend to know need to know where things are before you can squirt radio waves up them together reflection that's a fair point. So that's assessment of the size of the office was.
Yeah a bit of an under.
Under reaction maybe.

[9:35] That's all fine or overreaction maybe I don't know but so it is a nasty one if it would ever hit us yeah so did he must have been worse
that's nearly 700 meters i think or 750 that's yeah but did he most is big enough that we would probably know about it already yeah we do yeah we do obviously we've been there done that now.

[9:58] It's actually in the main asteroid belt it's never going to come anywhere near the earth oh that's good news yeah but yeah we keep an eye out for um whatever may develop out there because.

[10:09] There's there are there are plenty of sources of asteroids and it just takes a nudge or a bumper a wink or you know under the table payment and it's on its way yeah forgive me i must correct.

[10:22] Myself i said that did he most is in the main asteroid belt it's not actually it is um one that comes within the uh in a solar system um but uh but it's always stable and we're cool i
suppose what we're getting at here is size when it comes to asteroids size does matter does indeed so how small is small enough for it not to do anything
two or three meters they probably come in every week right burn up in the atmosphere maybe as a fireball or an explosion in the atmosphere yeah as you know though you know the the event that's
the asteroid that hit the atmosphere above uh jelly blinks jelly beans that's right back in 2013 that was about 30 meters across and look at the damage that did yeah shockwave when it hit the ground
indeed yes um yeah we got lucky on that one didn't we all right so zach yeah it does um it does seem that um dimorphis could do some horrendous damage but you're right if it's a bigger object um we're
going to probably have to find other ways to redirect them because
that experiment probably was just small in the scheme of things and I think we've discussed the potential for multiple impacts on an object or painting it white on one side.

[11:46] It all depends on how long you've got. Yes. A long time then you can do all these tricks. Indeed. Zach, lovely to hear from you. Now we've got an email from Rusty in Donnybrook in Western.

[11:58] Australia. Hi Andrew and Fred. I'm wondering could dark matter be virtual matter? We know that virtual matter exists but we have no idea of its matter density. We know that VM pairs are extremely
short lived but do not exist in great numbers for tiny amounts of time. During that time if barionic in nature they should each have a tiny mass for that tiny time. Barion particles all have
positive mass so both members of any pair would not cancel with respect to mass. There could be a great deal of mass trapped within the fabric of space as virtual particles but we have not worked
out a way of quantifying it. Dark matter interacts gravitationally with ordinary matter and other dark matter. VM could also do this. There may be a flow of current VM as a result and this could explain the rotation of spirals and other dark matter phenomena. What do you think?
Thanks for the best podcast in the known universe Rusty. Thanks Rusty.
That's a really interesting theory. It is. And I'm just sort of trying to think about it. So virtual matter pairs are.

[13:21] I am pretty sure that everything of that kind is taken into account already in our assessment of the matter content of the universe. And it's true that you're probing a region of
space-time that I'm not an expert in, but I'm in a slight way surprised that Rusty has postulated this as an explanation for dark matter because virtual matter pairs popping in and out of existence.
Permeate the whole universe, not just where normal matter is. And so what I might have expected is Rusty to say is this an explanation for dark energy? Because dark energy is everywhere.
Dark matter isn't. Dark matter is not something that sort of spreads through the whole universe. And we know that it's distributed in a clumpy fashion just like the galaxies are in the universe.

[14:28] Now, my guess is that what would knock this idea on the head is gravitational lensing because for that to happen...
You need particles, you need something real, not something virtual, and it needs to be clumpy. Otherwise it doesn't work, you can't just have it popping in and out everywhere.
So, you know, imagining something that might, a flow of matter that might interact with real matter and speed up the rotation of spiral galaxies or whatever that is, I don't think that's a goer.
Because I think you'd struggle to explain dark, to explain gravitational lensing with this model. And now a particle physicist sitting here might just say, well, it doesn't work anyway because X, Y and Z.

[15:24] But I'm not one of those. So I'm not going to say that.
I'm just bringing my own personal view of this and hope that Rusty accepts it in the spirit of constructive debate. You certainly run the broom over our first two guests today, Fred.
Sorry, folks. Please tune in next week. It was nice knowing you, Zach and Rusty, and hope you come back again one day.

[15:50] But no, fair enough. I mean, it's a good question to ask. Maybe it was a typo, maybe he meant dark energy. Never mind. No, it's good.

[16:02] Alright, thanks, Rusty. Good to hear from you as always. This is Space Nuts with Andrew Dunkley and Professor Fred Watson. Roger, you're live. You're here also. Space Nuts.

[16:14] Now, being a Episode 330, we're just going to carry on with the questions. And the next question comes from, I hope, Trevor, who is also in Australia in a place called...Drewan, I think it's called.
Sorry about that Trevor. Now I've done it. Now he says, my questions are about our moon and its similarities to the sun. Our moon appears exactly the same size as the sun in the sky. It rises in
the east, it sets in the west, same as the sun. It traverses the northern sky as seen from the southern hemisphere, same as the sun. Its path across the sky changes with the seasons, same as
the sun. So my questions are how common is this within our solar system? Do the moons of other planets exhibit the same behavior as our moon? How did this affect early astronomers understanding
of the moon and the sun? Did the fact that the moon and the sun appeared to be the same size and behaved similarly help or hinder their understanding of what was going on in the heavens? Many thanks for your podcast. Damn fine question Trevor. Yeah, it's great stuff. It is great stuff. And.

[17:33] Better than Rusty's and Zach's. So the answer to Trevor's question is yes. All right. There you go.
And now the next question comes from...
It is the most extraordinary coincidence and you know, I think it's almost spooky This is such an amazing coincidence that the angular diameter of the moon and the angular diameter of the Sun.

[18:03] Are essentially the same. They do vary slightly, both of them, because the Earth has an elliptical orbit around the Sun so the Sun looks slightly bigger and slightly smaller at some times. Likewise, the moon has an elliptical orbit around the Earth.

[18:17] And so the moon looks smaller and larger. In fact, it varies by 14%, which is quite significant.
And that's why we get different sorts of eclipses. Sometimes the moon doesn't quite cover the disk of the Sun and we get an annular eclipse or a ring of fire as it's sometimes called.
So that, as I said, is a coincidence and it certainly would have exercised the minds of very early astronomers. I think it's one of the reasons why we have religion actually, because the moon's disk exactly covers the disk of the Sun
so periodically the Sun turns to blackness, which, if you didn't really know what was going on, would be a terrifying experience.
I imagine so. We know actually, Andrew, that Indigenous First Nations people here in Australia have original people. A lot of the dream time stories about the Sun and the Moon actually indicate that these people did understand.
Back to the earliest times, they understood what was happening. The moon was covering up the disk of the Sun and that's a stunning realisation. Makes the flat Earthes look even dumber, doesn't it?
Yes, yes, try. Well, yes, anyway. That's another story altogether. So it is a coincidence and when you look elsewhere in the solar system, yes there are.

[19:47] Eclipses by other bodies, the moons of other planets and you don't have to look very far to find a stunning video taken in April this year of Mars's bigger moons, FODO, Fobos in real time traversing the disk of the sun, seen from the by the perseverance rover. I remember that. Yeah, was spectacular.
And happened fast too, didn't it? It was like 30 seconds. Yeah, something like 40 seconds. Something like that. That's right. Yeah, it's extraordinary. I'm going to show that tonight in a talk I'm giving because it's such fabulous footage. So they do happen elsewhere, but there is nowhere else where they exactly cover the disk of the sun. The nearest is one of the moons of Saturn, a tiny moon of Saturn, that if you were standing on the.

[20:32] Upper cloud decks of Saturn, you would see this oval body kind of just about cover the disk of the sun. That's the nearest there is. So it's a remarkable coincidence. And the reason why the sun, you know, the moon follows the sun in the sky.
And it's path through the sky similes that's just because its orbit around the earth is not very different in terms of its
orientation to the orbit of the Sun, of the orbit of the Moon, sorry, the orbit of the Earth around the Sun. That's in a plane called the ecliptic
plane and the Moon's orbit is tilted at five degrees to the ecliptic plane so it's virtually the same and what that's telling you is that the Moon's
always going to be roughly in the same region of the sky as the Sun is or following it depending on the phase of the Moon. So yeah, interesting coincidence
is interesting stuff now well understood except for this curious similarity between the angular size of the Sun and the Moon and just one other
aspect of this, this is a temporary phenomenon. In about 300 million years it won't be doing that because the Moon will have drifted away and so yep. Make the
most of it while you can. Yes, yes. Go and watch any clips. Yeah and don't take too long or you'll never see it again. I suppose his question about.

[21:57] Whether or not early astronomers got an understanding of the Moon and the Sun because of this weird coincidence is a good one. I imagine though being.

[22:05] Astronomers they would have really puzzled over it and figured it out quite fast.
Yes, that's right. I think the ancient Greeks would have sussed this completely and knew how to predict eclipses as other early peoples did as well.

[22:29] I suppose we are guilty of being ignorant of the intelligence of past civilizations. I mean, I walked the streets of Pompeii a couple of weeks ago and honestly, I've got to tell you.

[22:42] It was like walking through any town or city that we know of today. The only thing they didn't have was electricity, but for all intents and purposes, it was a city like any other. It was just, you
know, old and made of rock, but it had streets, it had footpaths, it had shops, it had houses, it had...
Questionable premises. It had it had everything that a modern city has and you know to walk those streets just incredible. So don't underestimate the intelligence of ancient civilizations because.

[23:18] They knew what they were doing. We just assume we're better at it than the neighborhood. And it's not not an absolute. I don't think. And as you said, the indigenous peoples of Australia figured out the moon and the sun thousands upon thousands of years ago. All right. Great question, Trevor.
Thank you. And great to hear from you. Now let's go to a question from Judd and Lisa, who are patrons. So thank you for supporting Space Nuts financially. It's certainly appreciated.
And you know, we've been able to buy a lot of coffee. So hello, Andrew and Fred. Always enjoy your fascinating podcast. So I was watching an episode of QI recently that mentioned a bit of
space junk I hadn't heard before. It said that there is a theory that our moon originated from 12 smaller moons that gradually coalesced into one. Interesting theory. QI isn't my number one
source of space facts. So I'll put this to Fred. Any truth to the 13 moon idea? Why exactly 12?
Not thousands of smaller asteroids. What did they all? Why did they all?

[24:33] I'm lost my place here. Why did they all completely coalesce into one? We're trying to read across a widescreen. So I keep losing the beginning of the next line. Wouldn't there be stragglers drifting
around like the space junk we've added?
What is the most widely accepted theory of the origin of the moon? I think I'll recall one about a collision with a small molten earth that knocked a blob that became the moon.
Wouldn't want to have been around that day. No, me neither. That comes from Judd and Lisa in Sydney.
Thank you for your questions. The moon seems to be a popular topic this week.
Yes, indeed this is. As you dexpack with eclipses around. So really the question that's probably the one to go straight to in Judd and Lisa's.

[25:25] Text is it i can't remember it's an email yeah it's an email yeah is is what's the what's the current.

[25:32] You know most accepted theory of the origin of the moon and it certainly isn't that there were 12 moonlets that uh is one that i haven't come across before but it sounds as though it is right on the fringes of.
The currently accepted ideas of how the moon formed and i'm a bit surprised at qi but their fact checkers sometimes a little bit off the mark and actually they often get things about the moon wrong
oh i've noticed that yeah i don't watch qi these days because i'm time but when i used to uh that was it anyway um what is the most widely accepted view of the origin of the moon and it's exactly as jordan lisa say
uh the idea that the early earth was impacted by a large object something the size of mars.

[26:21] Um which uh when when it collided essentially removed a lot of the outer layers of the earth uh and blasted them into orbit around the earth so we've got a you know debris cloud around the earth
which itself eventually coalesces to form the moon and the main you know one of the main pieces of supporting evidence for that is the fact that the moon and the earth are basically made of the same rock.

[26:46] There are differences between them but but the the the bottom line is that most of the uh material of of the moon is the same as the stuff in the earth's mantle that's the outer layer.
Of the earth itself so um that's kind of very strong evidence which came from the apollo era moon missions very strong evidence that suggests that they have a common origin that they
they came from the same blob of stuff and in fact people are so confident of that theory that we've given that uh that colliding object to name it's called thea named after the the mother of the moon
um in Greek mythology if i remember rightly so that's the the most widely accepted view and
it would be hard to see how exactly this you know the questions that Judd and Lisa ask about the 12 moon idea why aren't there any leftover and things of that sort it would be hard to see how how you could make a moon like the one we've got today.
From a Lego building set of 12 objects I don't know how that would work at all.

[27:51] We do currently have two moons though don't we there's a small object that's been captured by the Earth's gravitational pull but it won't be permanent. That's right and it's probably a rocket
body I think. No I think this one is actually a rock okay but it's only tiny. These things do come and go. Yeah yeah that's what they said you said there were only slight differences between the Earth and the moon that being that the moon's partially made of Swiss cheese. Now apparently.
Yeah I just thought I'd throw that one in there because it's very important very important to be factual.

[28:28] All right did we cover all of their question? I think so yes I hope so anyway thank you very much. Well they do pay us so we want we want to cover it. Yeah absolutely.
Yes indeed. Thanks, Judd. Thanks, Lisa. Lovely to hear from you and thanks for supporting Space Nuts. You're with Andrew Dunkley and Professor Fred Watson.
0G and I feel fine. Space Nuts. OK, Fred. To wrap this up, we've got a couple of audio questions and the first one comes from someone who sends us a lot of questions and they're very astute.
And this one I like because when I played it for you in rehearsal, it tickled your fancy. You went, whoa, great question. So this is Buddy in Oregon.
Hi guys, this is Buddy from Oregon again. Just a real quick question this time. I was listening to an episode and you were talking about how the spin of the Earth doesn't affect time, and I get that. But if we were to reverse,
somehow reverse the spin of Earth, would that reel the moon in?
Or would they keep progressing out?

[29:42] Thanks guys, huge fan, you guys are awesome. Thank you buddy. Look, it's a great question and Superman has actually done that. But we don't know what happened to the moon. He reversed the.

[29:56] Spin of the earth so he could reverse time and save Lois. We all know that.

[30:02] That's what happened, was it? Yeah, of course, I do remember that. Yeah, I think I was there at the time actually. So yeah, it's a great question buddy and as with many of these the answer is,
it depends because okay, so if you had the spin of the earth reversed, but the rotation, sorry, the revolution of the moon around the earth continued in the same direction, then I think,
I really need to think about this a bit more carefully. So I'm talking off the top of my head here, but I think you'd reel the moon in. Oh, right. Because the gravitational bulge.

[30:48] Which the moon raises on the earth would be projected in the direction away from the moon's motion. And so that I think would slow down the revolution of the moon. Yeah, it would. It would
have a breaking effect on the moon. And when you break an object in orbit, you pull it in. So if the moon kept going in its same direction, but the earth suddenly spun the other way, yeah, we'd
pull the moon back. Okay. That would be a very interesting phenomenon. But anything that would reverse the spin of the earth might reverse the direction of the moon as well, in which case it
would still keep drifting away from it. Yeah, I suppose that would have to have to be a factor. I mean, I wouldn't imagine it had hauled it into the point where it would smash into us.

[31:37] What? No, I don't think so. I think you still get a stable outcome at the end of it.
But yes. I suppose also, I love these what if questions, if you didn't already know. But if you reverse the spin of the earth and the moon kept going the way it is now.
It would lap us twice as fast wouldn't it? Yeah that's right yeah it will be quite phenomenal the speed at which it would appear to go through the sky. And that would have to have a high impact
on tides and life on earth in general. It's such a counter-intuitive thing. It would still go around wanting a moon. But it would...
It would certainly change the way it goes through the sky to be used to go through the sky with the diamond rotation of the moon. See what you started buddy.
Hmm started the old brain cells with a buddy there until you get your thinking i love the question it's a really good one and thanks for sending it in. Now Fred one more question to finish off this week's episode and this one's fairly close to home for you at self explanatory to.

[32:54] Hi Fred and Andrew, my name is Barry Brook and I knew Fred when I was a lad living up at sighting spring in the 1980s. Fred had no doubt remember my dad Graham Brook who worked up there
as electronics technician for about 13 years at the site. It's always been fun to hear Fred's voice over the last seven years anyway during which time I must have listened to all 320 episodes I think.

[33:15] Anyway to my question, given that we're now entering the age of giant ground-based telescopes that was adaptive optics like the LT and they're situated in ideal isolated dry high altitude sites.
I was wondering if there was any role left to play for existing mid-sized instruments like the UK Schmidt 2.3 meter or even the AAT.
Do you think they can be upgraded to keep pace or at least continue to fulfill a meaningful scientific role? I noticed that even at Sighting Spring there seems to be a recent focus on building smaller specialized instruments like SkyMapper and the Huntsman.
Are they the future of the Sight?
Anyway thanks both and keep up the terrific podcast thanks Barry lovely to hear from you there's a little bit of a bolt from the past Fred yes and Barry is completely modest because he hasn't
mentioned that he's actually a professor himself oh and just thinking back I've run into Barry a few times you know over there
decades and it's always a delight to see him and I do remember his father Graham well but and I'm I apologize Barry but I can't remember what you are a professor of but I do remember.

[34:33] Being very impressed with your academic you know academic achievements because I seem to remember you won some awards as well these are all locked in there somewhere so great to hear your question
great to talk to you but I think your question is actually absolutely on the money you know we've got an era now where the best observing sites for optical telescopes the best observing sites in the
world are about half a dozen if that's mountaintops many of which certainly many of the southern hemisphere ones are in northern Chile where conditions are probably the best in the world
or for optical astronomy some would argue that Antarctica is better because they have some excellent conditions there too but there are other issues that come to play in Antarctica.

[35:30] Not the least of which you you only see half the sky and you only see for half a year so you know that they're all issues but certainly northern Chile is where things like the very large telescope.

[35:43] The suite of telescopes that European Southern Observatory runs which Australian astronomers have access to now and the and the coming ELT the extremely large telescope which will be at.

[35:53] Saro Amazonas in northern Chile and not forgetting the the planned HLT the honkingly large telescope
We've all got one of those in the back of our mind. I like the idea, yes, yes, we're honkingly large. I used to call it the SBT for the phenomenally big telescope because by then people won't be able to spell.
So it's, you know, anyway, that's fine. And I was about to correct you.
The bottom line is that so the ELT the European telescope at Sarro Amazon is will be exactly 10 times the diameter of the Anglo-Australian telescope which has a 3.9 meter mirror this
will have a 39 meter mirror. Wow. And that is going to show us things that the AT never could because of course you're talking about very faint objects which come into focus with a big
telescope like that. So it's tempting to think that you know instruments like this and the you know the current 8 to 10 meter class of telescopes which are today's workhorses of astronomy that
they might be redundant.
I don't actually know whether that will ever happen The issue of what you do with these telescopes is reasonably clear cut.

[37:20] Many of the four metre class telescopes in the world, and there were several Built at the same time as the Engl Australian Telescope here in New South Wales Back in the 70s and 80s, many of those are now...

[37:33] Sorry! Thought I had that on mute With a musical introduction, they are now what you call single purpose telescopes.

[37:43] So they've got an instrument that lets them do one job Like one that's run by the European Southern Observatory, 3.6 metre.

[37:53] That has an instrument on that's finding planets, it's called HABS I've heard of that one And some of the big telescopes in the Northern Hemisphere, the four metre class One of them's got a...

[38:08] Sort of survey type facility on it to measure lots and lots of stars and planets. So these things do compress rather than trying to be all things to all astronomers which they were when they were
built, the four meter class telescopes now generally are single purpose. Actually the angle Australian telescope is still offering five different instruments and that makes it quite
unique in this world or almost unique. But it comes with a price in the sense that the economics of this is such that you've got to have a big crew to operate an old telescope with many different
facilities. So there may be a time in the future when the angle Australian telescope just becomes a one facility instrument. A one-trick pony. Yeah and that's a nice name for it. I thought it was insulting.

[39:04] Yeah just fine as long as it you know it keeps the telescope operating. As long as it's a good trick. And it's a good trick. The other thing about these telescopes certainly in regard to the
angle Australian telescope is that it has it's on Australian soil. It's not on the best the most supreme sites in the world. These are in northern Chile as I said in the summer hemisphere. It's in
a climate where you've got perhaps two-thirds of the nights are clear. You've got...
Not quite the best atmospheric turbulence it can be very good but it doesn't match the Chilean size and that's the important criterion but it's in Australia and what that means is that you've got.

[39:47] A workhorse on which people can try out new ideas for instruments so it's a test bed for new instruments and that's happened with the UK Schmidt telescope that Barry also mentioned that's been a test bed for a number of new instruments the angle Australian telescope is as well.
Plus it lets you train astronomers on a telescope where they don't have to go halfway across the world.

[40:11] They can use it on Australian sites with perhaps less competition for time on that telescope so there is a role for them now whether that role will extend more than 20 or 30 years I don't know.
I think perhaps in a decade people will be looking seriously at some of these telescopes and asking whether they are viable none of the four meter class telescopes have yet closed and that
includes the one another that Barry mentioned the United Kingdom infrared telescope although I think that's the one that may well be the first to close if and when it does so retrofitting them and.
Yeah updating them putting new equipment on that's right that may be the option it well that's what's happened that's why they're still competitive today in an era of eight to ten meter class telescopes
but not a permanent fix it's their ultimate they're going to reach an end date I think that's probably right yes I don't know when it will be though yeah but it's actually part of my job Andrew
is looking at the long-term future of the anglo-australian telescope
hoping that we can find the money to keep running it. Yeah, all comes down to money, doesn't it? Does in the end. All right. Thank you, Barry. And great to hear from you. And thanks
for your backstory, even though you left out the most important bit, which is your scholastic achievement. But that's okay. A lot of people don't like to skyten. That's fine. Fred did it for you.
That wraps it up, Fred. Thank you so much.

[41:39] It's been great hasn't it and welcome back again Andrew from your Sojourns in Europe and we'll talk again very soon. We will indeed and don't forget if you've got questions for us send them through
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