October 20, 2025 • 42 mins
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This episode is brought to you with the support of NordVPN....enhance your online privacy with the best in the game. To get our special Space Nuts price and bonus deal, visit www.nordvpn.com/spacenuts or use the code SPACENUTS at checkout.
Q&A Edition: Dark Matter, Betelgeuse, and Lagrange Points
In this fascinating episode of Space Nuts, hosts Andrew Dunkley and Professor Jonti Horner tackle a variety of listener questions that delve into the mysteries of the cosmos. From the enigmatic nature of dark matter and its interactions with black holes to the potential explosion of Betelgeuse and the intriguing concept of Lagrange points, this episode is packed with thought-provoking insights and scientific discussions.
Episode Highlights:
- Dark Matter vs. Black Holes: Andrew and Jonti explore the relationship between dark matter and black holes, discussing whether dark matter can be 'eaten' by black holes and the implications of such interactions for our understanding of the universe.
- Betelgeuse's Fate: The hosts address a listener's question about the distance of Betelgeuse and what it means for us if it were to explode. They explain how light travel time affects our perception of cosmic events and the philosophical implications of observing the universe.
- Lagrange Points Explained: Mark's inquiry leads to a detailed explanation of Lagrange points, their stability, and how they function within the gravitational dynamics of celestial bodies. Jonti provides a compelling analogy to help visualize these unique gravitational wells.
- Kordeski Plasma Clouds: The episode wraps up with a discussion on the Kordeski clouds, two large dust clouds located at the Earth-Moon Lagrange points. The hosts delve into their transient nature and the challenges faced in confirming their existence.
For more Space Nuts, including our continuously updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on Facebook, X, YouTube Music Music, Tumblr, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favorite platform.
If you’d like to help support Space Nuts and join our growing family of insiders for commercial-free episodes and more, visit spacenutspodcast.com/about.
Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
Got a question for our Q&A episode? https://spacenutspodcast.com/ama
Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support.
This episode is brought to you with the support of NordVPN....enhance your online privacy with the best in the game. To get our special Space Nuts price and bonus deal, visit www.nordvpn.com/spacenuts or use the code SPACENUTS at checkout.
Q&A Edition: Dark Matter, Betelgeuse, and Lagrange Points
In this fascinating episode of Space Nuts, hosts Andrew Dunkley and Professor Jonti Horner tackle a variety of listener questions that delve into the mysteries of the cosmos. From the enigmatic nature of dark matter and its interactions with black holes to the potential explosion of Betelgeuse and the intriguing concept of Lagrange points, this episode is packed with thought-provoking insights and scientific discussions.
Episode Highlights:
- Dark Matter vs. Black Holes: Andrew and Jonti explore the relationship between dark matter and black holes, discussing whether dark matter can be 'eaten' by black holes and the implications of such interactions for our understanding of the universe.
- Betelgeuse's Fate: The hosts address a listener's question about the distance of Betelgeuse and what it means for us if it were to explode. They explain how light travel time affects our perception of cosmic events and the philosophical implications of observing the universe.
- Lagrange Points Explained: Mark's inquiry leads to a detailed explanation of Lagrange points, their stability, and how they function within the gravitational dynamics of celestial bodies. Jonti provides a compelling analogy to help visualize these unique gravitational wells.
- Kordeski Plasma Clouds: The episode wraps up with a discussion on the Kordeski clouds, two large dust clouds located at the Earth-Moon Lagrange points. The hosts delve into their transient nature and the challenges faced in confirming their existence.
For more Space Nuts, including our continuously updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on Facebook, X, YouTube Music Music, Tumblr, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favorite platform.
If you’d like to help support Space Nuts and join our growing family of insiders for commercial-free episodes and more, visit spacenutspodcast.com/about.
Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
Got a question for our Q&A episode? https://spacenutspodcast.com/ama
Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Hello again, thank you for joining us on Space Nuts
Q and A edition. This is where we answer audience questions,
or at least we read them out and pretend we
know what.
Speaker 2 (00:09):
We're talking about.
Speaker 1 (00:10):
Today we will be answering questions about dark matter versus
a black hole. It's a titanic struggle.
Speaker 2 (00:17):
Who would win.
Speaker 1 (00:19):
We are also going to discuss the demise of beetlejuice
or beetlegeis, depending on how you like to pronounce it.
We have a question about lagrange points and the Cordeleski
plasma clouds question has.
Speaker 2 (00:35):
Come up from a YouTuber.
Speaker 1 (00:37):
We'll deal with all that right now on Space Nuts.
Speaker 3 (00:40):
Fifteen second Channel ten nine ignition Squench Space Nuts or
three two.
Speaker 4 (00:53):
Space nuts as.
Speaker 5 (00:54):
And I reported Neils good.
Speaker 2 (00:57):
He's back again for more.
Speaker 1 (00:58):
Has done all the research, has all the answers to
all the questions, except for those four. It's Johnny Horner,
professor of astrophysics at the University of Southern Queensland.
Speaker 2 (01:07):
Johnny, Hello, I'm good afternoon.
Speaker 4 (01:09):
How are you doing.
Speaker 2 (01:10):
I'm all right.
Speaker 1 (01:10):
How are the renots going at your place?
Speaker 4 (01:12):
Well, not too bad. I think they've clocked off for
lunch at the minute, so we might get away with
it on I'm waiting for my other doctor insists I
pay attention to her. Are you yes?
Speaker 2 (01:21):
Dogs do that? Yes, indeed they do.
Speaker 1 (01:25):
All right, let's answer some questions. Firstly, we've got a
question from Howard. He said, first, I should say that
I think dark matter is going to end up as
a follergiston? Is that the word of our times?
Speaker 2 (01:41):
Sorry? Flodgist?
Speaker 1 (01:44):
Could be that of our times, a substance dreamed up
to resolve an otherwise unsolvable problem and later discarded as
science advances. But even so, here's my question. Since gravity
seems to be the only force that interacts with dark matter,
what happens when a black hole, the ultimate source of gravity,
comes into contact with dark matter? Does it eat it?
(02:06):
And if so, what happens? And if not, why not?
Speaker 2 (02:10):
I do?
Speaker 1 (02:10):
We've had questions of similar style and ilk before, and
I can't remember what Fred said, but I think it
said doesn't matter, you know, because dark matter? And yeah,
but I'm sure you've done your homework, because I didn't.
I never did homework as a kid, so why would
(02:31):
I start now?
Speaker 4 (02:32):
Well, there seems to be evidence that homework is fairly pointless. Such, yes,
my Apartner's a primary teacher, and you know, I think
if she had her where, kids wouldn't have any homework,
and at least until you're fairly well through secondary school,
it doesn't seem to serve a purpose other than making
some parents feel like their kids are getting properly worked,
you know. So, but onto something that I actually have
(02:54):
expertise in, rather than being talking about teaching what I
clearly done that much, is a real interesting one. It's
I get what you mean with the flogist, and I
think possibly dark energy, i'd argue, is a bit more
of a flogist and thing than that matter at this stage,
because it's very clear that there is mass out there
(03:14):
that it's having an effect but we can't see. And
that's fundamentally what dark matter is. We can add up
all of the mass of all of the things that
we can see in the forms of dust and gas
and stars and all the rest of it, and the
gravitational pull within galaxies, particularly as you get further out
into galaxies, is more significant than can be explained by
(03:34):
the luminous material art and that's where dark matter comes from,
and we see its effects even if we don't see
it in I guess just the same way as back
in the eighteen hundreds, astronomers saw the effects of Uranus
of Neptune's gravity perturbing the orbit of Uranus as it
went round the Sun, and we detected Neptune indirectly. And
(03:55):
then people said, only point you tell it's goope here,
because it must be a planet in this part of
the sky pulling Urinus around and low, and behold, we
found it. And this is fairly fundamental to me as
an exoplanet science person, in that the vast majority of
planets we found around o the cells we found indirectly.
We see a star doing something unexplained, We see it
winking or we see it wobbling, and we in further
(04:17):
presence of a planet as an explanation for that unexplained behavior.
And when you rule out all the other explanations, someone
that's left as a planet, and Bob's your uncle. You've
added one to the Italian. Like we said in the
earlier episode, we've now passed six cells, and so whoopy
for us, we're doing really well. So there's a lot
of evidence that dark matter is a thing, and what
it is nobody really knows. There's been a lot of speculation,
(04:40):
but what seems to be the case is that dark
matter is something that interacts through gravity but doesn't interact
with anything else. It doesn't interact with light. It doesn't
impede light because we see dust blots light, so dust
is not dark matter. So what happens, Well, if dark
matter interacts with gravity in just the same way as
normal matter, then it will interact with a black hole
(05:02):
in almost the same way as normal matter. And they
almost said a little asterisk. I'll come to in a minute.
What that means is that if something gets close enough
to a black hole to be within its event horizon,
then that means it would have to travel faster than
the speed of light to escape from the gravitational pull
of the black hole. So it's effectively been nombed. And
you've got black holes being the pack man of the
(05:23):
universe that just go around gobbling everything up. Once it
is gobbled up, it doesn't matter if it's dark matter
or normal matter. It's been nombed and it just adds
to the mass of the black hole. And I guess
the black hole is a bit like the ball, and
it's your individuality. Indistinctiveness has been added to our own
and the dark matter has been nombed in just the
same way it would have been with normal matter. So
(05:44):
from that point of view, there is actually no problem.
We'd expect dark matter to be eaten and to stay eaten.
There are suggestions that the supermassive black holes like the
one we've got at the middle of the Milky Way
are only able to be formed if that matter exists,
and even more normal mass black holes have a restriction
(06:08):
on the amount that they can eat. It's almost like
the celestial equivalent of a gastric band or something like that.
It's something called the Eddington limit. Material falling into a
black hole, that is normal matter as it falls in
gets accelerated, gets heated up in its light. And if
you've got a black hole eating a lot of stuff,
(06:28):
there's a lot of material falling and emitting incredible aunts
of radiation. They can essentially push away or the matter
around the black hole and force it to stop eating,
effectively putting a limit on the amount that it can
devour at any given time. And you do get things
that are eating at what's called super Eddington rates, but
(06:49):
that's where something's essentially pushing material in so quickly that
it overcomes that effect. So I guess it's a bit
like saying you can only drink so much water because
you can only swallow so much. But if somebody shoves
a fire hose in your mouth, the water's going to
go somewhere. That's kind of that situation. But that puts
a limit on how much a black hole can eat
(07:10):
at a given time. At the pace at which can
devour matter, dark matter doesn't interact with like al radiation
or anything like that, so the Eddington limit doesn't apply
because a black hole shining like a searchlight will not
impede the motion of dark matter one little bit. And
so there is an idea that actually dark matter is
a more effective food for black holes and normal matter
(07:34):
because dark matter circumvents the Gasrick band. It circumvents this
Eddington limit that prevents a black hole from eating to excess,
and that may actually have been a significant part of
how the supermassive black holes that we get in the
middle of galaxies actually got their start where they got
their start aided by dark matter. And so it's a
(07:55):
really interesting question because I had not really thought of
this until Howard's question. Came through and added a bit
of reading around. But it's actually one of these scenarios
where dark matter, it seems, is a help to black
holes rather than a hindrance, and therefore may help to
explain why the universe is and where that we see
it today, beyond just explaining the rotation curves of galaxies
(08:17):
and things like this, which is why it was hypothesized
in the first place.
Speaker 1 (08:20):
Okay, so you do believe there's interaction between dark matter
and black holes.
Speaker 4 (08:25):
Of course, Yeah, and sorry, of course the sounds to dismissive.
The reason that it's in, of course, is that dark
matter interacts with gravity. That's fundamentally how we found it
in the first place. And therefore, if it falls into
a black hole, it behaves like any other kind of
matter from the point of view gravity.
Speaker 2 (08:46):
And so therefore, and I.
Speaker 4 (08:47):
Mean, there are some suggestions that black holes are a
significant component of dark matter.
Speaker 2 (08:53):
Yes, we can only see them when they're feeding.
Speaker 4 (08:55):
If they're not eating anything, we have no indication of
black holes there other than its effect on the mass
around it. You know, light gets bent around it and
all the rest of it. Yeah, some component of dark
matter may well be primordial black holes. That's one of
a suggestion.
Speaker 1 (09:09):
Yeah, there's still so much to learn. We don't know
much at all, although they also I think if I
recall correctly say that dark matter clusters in around galaxies
and around concentrated points, it's much thinner where the universe
is emptier.
Speaker 2 (09:28):
Is that right?
Speaker 4 (09:30):
And that kind of makes sense as well, because if
dark matter is feeling the effects of gravity like everything else,
the same things that would have pulled an excess of
visible matter together to farm galaxies would have brought together dark.
Speaker 2 (09:41):
Matter as well.
Speaker 4 (09:42):
And there is this discussion that galaxies have dark matter
halos around them. So the rotation curves of galaxies are
evidence for dark matter within those galaxies, meaning that there
is more mass interior to a certain distance from the
middle of the galaxy than we can account for by
what we see. That means that together rotation happening quicker
because it's more master left on, more gravitational pulse or
(10:03):
faster rotation. But the massive galaxy clusters, in terms of
how the galaxies are interacting with each other and how
they're moving within the clusters, the mass within the cluster
has to been bigger than the masters that the galaxies
seem to have from the visible material, even accounting for
the dark matterrhithm causing their rotation speeds to be higher.
(10:24):
And that's suggesting that that matter is also in a
halo around the galaxy, given that galaxy even more muster
even more.
Speaker 2 (10:32):
Yes, it is so fascinating.
Speaker 1 (10:35):
And Flogiston was a hypothetical fire like element once thought
to be contained within combustible bodies and released during combustion,
a theory proposed by Johann Beecher, and it's an outdated
theory that was eventually disproved by Antoine Levosier through his
experience with oxygen, which demonstrated that burning is a chemical
(10:56):
reaction involving the combination of a substance with oxyde, not
the release of flogiston. There you are, all right, Howard,
Thank you so much for a great question. Let's take
a break from the show to tell you about our sponsor,
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Speaker 2 (12:36):
Now back to the show.
Speaker 1 (12:38):
Three space nuts now. Gary is next. He's a fan
from Canada's East Coast. I was only recently on Canada's
East Coast, visited Peggy's Cove and Halifax and lovely part
of the world. He goes on to say, I enjoy
your humor mixed with actual scientific knowledge out of part's
(13:00):
probably not anyway. Question, can you tell me if beetlejuice
Beetlegeiss explodes six hundred and eighty million light years away,
whether we are just seeing something that happened six hundred
and eighty million years ago, traveling at the speed of light.
Speaker 4 (13:17):
It's a really good question. It comes a plot when
I'm doing outreach and stuff like that. Beetlejuice is depending
on whose measurements you expect, it's not quite six hundred
and eighty million light years away. It's somewhere between about
five hundred and seven hundred light years away, so it's
a bit closer to home than that. But the question
still stands. When we see objects in the universe, we
(13:39):
see them as they were when the light was emitted
from them, and that's even true for the rumor around you.
It's just that everything nearby is cell class that you're
effectively seeing instantaneously. Light travels at three hundred thousand kilometers
a second, so we see the moon, which is about
three hundred and eighty four thousand kilometers away, worrying. We
(14:00):
just had all the fuss about the supermoon's yet again.
So the distance to the Moon does very a little bit,
but that means we see the Moon using light that
reflected off the surface of the Moon about one and
one third seconds ago. It's one and one third light
seconds away. We see the Sun with light that left
the surface of the photosphere a bit more than eight
minutes ago. And so when you see anything, you're seeing
(14:24):
light that left a period of time ago. You see
everything as it was in the past, rather than as
it would be in a perverse now that if you
could teleport there instantaneously, it would look different. I mean
that brings into question could you teleport at faster than
the speed of light? But then the question is kind
of teleport anyway, So that's getting getting into the grounds
(14:44):
of science fiction. But it brings open a odd philosophical
kind of question, which is what do you define as
something happening now? Do you define them now as a
perceived now where you are, or do you find now
as being the time that the event happens, that the
(15:06):
light would reach you once it has traveled that business
to get to you. And I'm explaining that badly. But
this is essentially the fundamental of the question. If Beetlejuice
exploded a thousand years ago, on that light reaches as say,
three hundred years in the future, So it turns out
it was seven hundred light years away. Beetlejuice exploded a
(15:27):
thousand years ago, the light travels for seven hundred years,
so it all reaches in three hundred years seven. I'm
sure my head has got flipped over there somewhere. But
on if Beetlejuice exploded a thousand years ago, we saw
it three hundred years in the future, then that'd be
thirteen hundred light years away. That's I'm going the wrong way.
But anyway, we know, if you have exploded in the past,
we see it at some point in the future. Did
(15:49):
that explosion happen in the past of the future? Well,
in Beetlejuice's frame of reference, if you were stood camping
near Beetlejuice, you would have seen it in the past.
You'd have seen it happen already. But any signal you
sent to tell us that it had have happened would
only just arrive at the same time that the explosion did,
because you'd have to see it first, and then the
signal back. So from the point of view of us
(16:11):
here on Earth, when does beetlejuice explode? Is it when
we see it or when we calculate back how long
ago that explosion had to happen for us to see
it today. And it's where we get into the philosophy
of perception and what it actually means to be now,
because everything around us, even the tip of my own nose,
(16:31):
is far enough away that I'm seeing it in the past.
I mean, I'm seeing it in the past by nane
oh seconds, but it's still in the past. And so
there's a weird bit of internal philosophy that has to
go on there that is driven by the size of
the universe. And we came up with this fine with sound.
We see a flash of lightning and then we hear
(16:53):
a rumble of thunder a certain amount of time later,
and we're aware that the two events happened at the
same time, but the sound takes a certain amount of
time to reach us. So if we imagine that there
was some form of instantaneous communication that could happen that
happened faster than the speed of light, and we were
able to have a real ay near beetlejuice. Tellers, beetlejuice
(17:14):
has now gone back, you will see it in seven
hundred years time. Then it makes sense to say that
beetlejuice ex blooded in the past and we only see
it now. But from your perception point of view, you'd
see it happening now when you saw it happen now,
and that will be all now. And so this is
a really fun question because the reality is that it's
(17:35):
all to do with frames of reference and where you stand.
And yeah, I'm listening to a fairly pulpy science fiction
series at the minute called Expeditionary Force that actually talks
about how slow light is when you're having combat happening
in space. You know, if you're shooting lasers and mazers
that people neural lights second away from them. By the
time your laser gets there, they'll have moved, so you've
(17:58):
got to shoot whether going to be not whether they
actually are, but then they know that, so they're dodging.
And the further away you are, the longer it takes
for the light to reach you. So you've got the
bisarre thing of if you can jump through space and
you can go through a wormhole and pay someone else.
You could fight someone and then jump through space and
watch the battle happen and watch yourself fight them.
Speaker 2 (18:17):
Wow.
Speaker 4 (18:17):
And this is where all the philosophy starts to mess
with your head. But it makes for wonderful science fiction
scenarios so long as you build something into your science
fiction world that allows you to have faster than light
travel so you can get ahead of the images of
yourself doing a certain thing.
Speaker 1 (18:34):
That is really interesting. I love science fiction for that
reason because you can just make all this stuff happen
that it is not yet achievable as far as we know.
Speaker 4 (18:43):
There must be is our example. So that when I
was young, I remember the Anne McCaffrey novels really well.
And you know, she was most famous across for the
Dragons series. You know, all the books about people in
a world where they live and bond with dragons and
they burned thread from the end, it turns out that
it's actually a soft sci fi setting rather than a
fantasy setting because reasons you find further down the series.
(19:04):
But she also had a series of books about the
Talents of Earth, which were these people with psychokinetic and
telepathic talents who could transport things using the power of
the mind from one place to one other, and they
could communicate telekinetically. And of course what you do with
people like that in Aan McCaffrey's world is not turn
them into soldiers and warriors like Marvel or the X
Men would do it, but you turn them into the
(19:26):
postal service, and the people effectively become the method by
which we send people to other stars. And if you're
a powerful enough telekinetic, you can pick something up on
Earth and send it to Capella and it'll appear there.
But then they had really powerful telescopes, and they have
had to be really powerful telescopes the first time they
tried sending things to another star, and they'll look at
(19:46):
that start and psychic person goes wibily wobbly, whibly wobbly,
and the thing disappears, and then it appears x to Capella,
and that's all well and good until somebody points out
the fact that the light was seeing from Capella left
it thirty years ago and we've just seen that thing arrive,
so they've obviously teleported it back through time. And then
you end up with this bizarre world where you've got
(20:07):
this web of world's vast distances from each other that
are linked by these postal service workers effectively, who can
from an instant communication instant transportation. But in order to
have it the instant and to maintain the current, now
they've had to send things back in time. But that
that means if they send them back in time, but
(20:28):
they can communicate instantaneously in both directions, could they tell
you thirty years ago to not send them.
Speaker 5 (20:34):
Yeah, it's a similar story in terms of the Dune
sci fi series, because same thing.
Speaker 1 (20:44):
They fold space, so you can go instantly from one
planet to Dune. But it's based on what you just said,
that's not the case. They'd have to be going back
in time as well.
Speaker 4 (20:58):
Yeah, and the un stuff got that part right. But
then you do have that thing of if it can
communicate instantaneously both ways, then you're communicating back in time
by thirty years. But if they then looked back at Earth,
they would see Earth as it was sixty years earlier,
except thirty years back in time. Looking back thirty years,
it strikes me that with big enough telescopes that would
(21:20):
I mean, it's a science fiction world, so we've already
broken the laws of physics. But you would make detective
work and police work totally redundant, because what you do
is you'd say there was a crime last night, Right,
we'll teleport someone fourteen hours away so they're looking back
twenty eight hours, so they can just look back and
see what happened.
Speaker 1 (21:38):
Yes, yeah, it makes I love I love it.
Speaker 2 (21:43):
I love these impossible scenarios.
Speaker 1 (21:47):
But you know, one day they might come up with
a way of doing some weird stuff that we can't
explain today, and there'll be some logic attached to it.
Speaker 4 (21:56):
But I'm sure if we were podcasting one hundred and
twenty five years ago, people will come so he couldn't
have a heavier heavier than their flight, and look how
that worked out.
Speaker 1 (22:04):
Yeah, exactly, all right, Thank you Gary. Hopefully we covered
that question for you. This is Space Nets with Andrew
Dunkley and John y Jonna. Okay, we take all for
space Nuts. Next question, Oh, we're still in Canada. This
question comes from Mark.
Speaker 6 (22:26):
Hi. It's Mark in London and Canada. I'm current listening
to all the back episodes, so I'm in March twenty
twenty one, so if you answer my question, it might
take me a while to hear it. But I was
wondering about lagrange points and the way they're describe as
a gravitational well, and we can send satellites there to
(22:51):
orbit around them.
Speaker 1 (22:52):
Is there a way to.
Speaker 6 (22:54):
Define the mass of the lagrange point? Like, obviously there's
nothing there, it doesn't atch you have a mass, but
we define or we observe things orbiting, and we can
define the mass of all those objects. So when you
see a satellite or design a satellite to go into
orbit around a lagrange point, is there an equivalent mass
(23:18):
that it's orbiting. That's obviously created by the whole system
of the larger objects, But is that does that mass?
Is it definable? Thanks Gat, Thank you Mark.
Speaker 1 (23:32):
So Mark's actually demonstrating time travel. He's listening to us
in the past, but we're hearing him today.
Speaker 4 (23:39):
I was just thinking of that. So the question is
when Mark listens to this answer, is he listening to
in twenty twenty five or twenty twenty nine.
Speaker 1 (23:46):
H's that's a good point, very interesting, and yeah, thanks
for the question, Mark. So we're looking at lagrange points.
Speaker 2 (23:55):
Our next question actually kind of focuses on that as well.
Speaker 1 (23:59):
Lagrange point points, gravitation wheels, the mess of a lagarage
point I think was the gats of his question.
Speaker 4 (24:06):
And it's a really interesting question. In fact, I've got
a pH d student, part time student working with me
who asked a very similar question a couple of months ago,
because he's going to be working and looking at the
Nettune Trojans, which are trapped around the L four and
L five O the grand points of Neptune, and they're
library around following this kind of kidney shaped path over
a period of hundreds of years around this point sixty
(24:28):
degrees ahead or behind Neptune.
Speaker 2 (24:29):
And it so, but.
Speaker 4 (24:31):
What's going on here is, well, take a little bit
of a deeto. When I was a kid, I was
a member of the Scouts, and me too. When you
were in the Scouts and you went walking around the countryside,
you had an Ordermance survey map. And I don't know
if that's called the same thing overseas, but that's what
it was in the UK. And what this map had
was a map of all the roads and all the
hills and all the rest of it, but drawn on
(24:53):
it were contours, and all points on a given contour
were the same height.
Speaker 2 (24:57):
Above sea level yep.
Speaker 4 (24:58):
And so you could tell how told the hills will
how seep the valleys where all the rest of it.
What those maps actually are are maps of gravitational potential.
So all objects at the same distance from the center
of the Earth have the same gravitational potential, and you
join them up with a contour that's exactly the same thing.
So if you make a hypothetical simplified solar system where
(25:20):
you just have the Earth while the Earth and the
Moon's mush into one and the Sun and nothing else,
you can make a contour map where you measure where
you calculate the gravitational potential every location in the solar system,
and then you do the same kind of map. You
join the points that have the same gravitational potential by
a contour, and you get a contoon map, and that
(25:44):
is fundamentally the same as your ordinan survey map. Points
that have the same gravitational potential will be metaphorically at
the same altitude above sea level, same distance above sea
level as a solar system. Now, if you draw a
line directly between the Sun and the Earth, the Sun
is at the bottom of an enormous blooming hole. You know,
(26:04):
the contours are circular around it. The Earth is at
the bottom of a smaller hole, and this is where
the whole metaphor of weights on a rubber sheet bowing
the rubber sheet comes from. So the Earth is at
the bottom of its own hole that is smaller than
the hole that the Sun makes. And so if you
have a line between them, you effectively come up all
from the Sun until you reach a certain point, and
(26:24):
then you tip over and you sat falling down the earthshole.
So you go downhill again. So between the two you've
got like a saddle point where at the top of
that saddle you're at a flat point where s basically
gravitational potential is flat and you could balance, Say you
could put a marble there and it would sit there.
But if that marble goes slightly off in either direction,
it'll roll down the hill.
Speaker 2 (26:44):
So if you get a.
Speaker 4 (26:45):
Little bit closer, then you'll fall off and roll towards
the Sun. If you get a little bit closer to
the Earth, you'll roll off and roll towards the Earth. Now,
if you move out from two dimensions between the Earth
and some three dimensions, if you roll clockwise or anti
clockwise away from that saddle point, you'll actually be trying
to roll uphill, so you'll fall back down into it.
So you've got this kind of really is like a
(27:07):
saddle point, where towards the Sun and towards the Earth
you fall downhill, but at right angles to that you
try and roll up hill. So you've got this local
flat area where if you move a little bit ahead
or behind it in your orbit, you'll roll back down.
So you've got a bit of a restoring force there,
but if you roll inward or outward.
Speaker 2 (27:25):
You'll fall off the hill.
Speaker 4 (27:27):
And that's why that lagrange point is an unstable one.
It's like a saddle point. And the three lagrange points
that are on the line between the Earth and the Sun,
L one, which is between the Earth and the Sun,
L two, which is on the far side of the
Earth beyond the Earth but on that line, and L three,
which is on the far side of the Sun opposite
the Earth. Yeah, those points are all these kind of
(27:49):
saddle points, so they're a bit more stable than normal
space because you can imagine balancing on the flat part
of the hill, but if you roll in either direction,
you fall away. Now a lot of there are spacecraft
sit at the inner or the outer lagrange point L
one or L two. The ones at L one sit
there because they can observe the Sun and give us
prior warning if something's coming our way cell a mass ejection,
(28:10):
something like that. The ones at L two sit there
to be in a good position to observe space, but
have station keeping with the Earth. They move around with
the Earth, and that seems like the James Web Space telescope.
But because those locations are these kind of saddle points,
they're not perfectly stable. Those spacecraft have to have fuel
to stay on stations, so if they start to drift downhill,
they can push themselves back up and get back to
(28:33):
the saddle point. And they actually do this by wabbling
and librating around that point and have a little orbit.
The other two lagrange points are L four and O five,
or sixty degrees ahead and behind the Earth in its
orbit around the Sun, and these are like enormous flat plateaus.
If you look at a contour map of the gravitational
potential of the cell system, you get these big kidney
(28:53):
shaped areas that are pretty flat, and that means if
you have your ball there, it could just sit there,
even if you're quite a long way away from the
center point of that lagrange point. You'd sit on one
of these contours, and if you start to roll, you'd
follow the contoe around, and you'd follow this kind of
kidney shipped path, staying trapped around the lagrange point but
vibrating around it. And they're like plateaus, so they're much
(29:16):
more stable than the kind of saddle points, and that's
why those are the points which in the outer Solar
System have huge populations. In the orbit of Jupiter, have
big populations in the orbit of Neptune. Those are the
Juter and Neptune trojans. The other planets can have trojans too,
but they tend to be temporary because the Solar System
is not simply three objects, it's actually got all the planets.
(29:38):
So if you're sadden near the lagrange points of Earth,
you're getting gravitational pulls from Venus and Mars nearby, from
Jupter and all the other planets as well, and eventually
they'll pull you off the stable plateau and you'll fall away,
so you'll only live there temporarily. Yea. But for Jupter
and Neptune, those planets are so dominant compared to the
other things around. They can hold things permanently at the
least Lagrange points, and the motion of a objects at
(30:00):
the alpha and l five points is that over hundreds
of orbits, they we'll gradually librate around that alphour point,
so they'll be on average sixty degrees our head or
behind the planet, but they'll be moving around that and
they'll be orbiting it. So the concept of trying to
think about whether you can define a mass at the
center of the la Grange point that holds them is
not quite the physics that's going on. That librating around
(30:24):
that point only works if you're in a frame of
reference that is rotating with the orbit of the planet.
So you're let's imagine we're looking at the Jupiter trojans.
You imagine you somehow suspended above the plane of the
Solar System, lying there, watching all the objects in the
Solar System, and you're spinning once every twelve years, just
as Jupiter orbits are some once every twelve years. So
(30:45):
from your point of view, Jupiter and the Sun stain
exactly the same place in your field of view. And
then over much longer time scales of hundreds of years,
these trojans would appay to orbit thet lagrange point. I
guess you could if you wanted to try and construct
some more to visualize that way. You imagine that there
is a virtual mass at the Vela Grange points, and
that's what the trogans are orbiting while they'll librate. It
(31:08):
would have to be a spread out mass because if
it was a point mass, they'd have much more circular orbits,
they wouldn't have these kidney shaped things, so the Masso'd
have to be spread out. But you could, I guess,
visualize it and calculate it, but that would only be
valid in the rotating reference frame, which is a bit
of a conceit anyway. In the normal scheme of things,
(31:29):
where everything's rotating around and you're not spinning above watching it,
these objects are moving on orbitstead of very similar period
to say Jupiter, but slightly longer, slightly shorter, and as
they pull if it's a slightly short orbital period than Jupiter,
gradually they'll insure head of Jupe to get further and
further ahead. Eventually they drift outwards and they're now further
from the Sun, so they're now going around the Sun
(31:51):
slower than Jupiter. And they sat fall back towards it
until Jupiter's gravity tweaks them and they fall inwards a
better than they start moving quicker. So it's actually all
down to the traction between Ju to the Sun and
the object in that case, rather than a virtual mass
off there. So I can see what you're thinking about,
and I can see it as being something that is
a good model to help you visualize what's going on,
(32:13):
But it's not the kind of thing we do calculations of,
and I don't think it's a sufficiently advanced mental model
that you'd want to get to that level with because
it starts taking down a rabbit hole of the physics
doesn't actually work that way, and you can put yourself
in traps when you do that. But it is a
really nice way to visualize initially how it works. It's
(32:35):
if you're librating around one of the lagrange points, it
is as though there is a force keeping you trug
to it. So it's as though there is a mass there,
keeping attracting you towards the lagrange point. It's just that
that isn't actually a mass there. It's simpler to do
with the intraction of all the other objects floating around
that create that virtual thing that keeps you locked around
(32:55):
that place.
Speaker 1 (32:56):
M hm okay ho'pefully then helped you out, Man.
Speaker 4 (33:02):
Broad piece MutS.
Speaker 1 (33:05):
And our next question and our final question kind of
relates to this question that Mark raised, And this came
from a YouTuber. I don't know their name, but that's okay.
Can you do a deep dive on the Cordleski plasma
clouds or do we not have much information on these
strange things now I look them up. The Cordleski or
(33:29):
Cordleuski clouds are two large, tenuous dust clouds located at
L four and L five lagrange points of the Earth
Moon system. Originally predicted in the nineteen fifties, first spotted
in the sixties, their existence was long doubted, but recently
confirmed in twenty eighteen by observations using a polarizing filter
that detected reflected sunlight from the dust. While they are
(33:53):
called dust clouds, summary research suggests they are a complex
a complex form of dusty PLASMI ah, yes.
Speaker 4 (34:01):
So this is a fascinating question. The Koondleshki clouds are transient,
and I think that's probably part of why they've been
hard to confirm because there are areas where as we
just described those lagrange points. If you only have the
Earth and the Moon in space and nothing else, then
the leading alpha and OL five lagrange points of the
(34:22):
Moon could be stable on million year, billionaire time scales.
But in actuality in the system where you've got the Sun,
you've got all the other planets, and for small objects,
the influence of the solar wind and the Sun's radiation
becomes significant as well. What that means is that it
becomes easier to escape from those lagrange points. By being
(34:43):
easier to escape, it also means it's easy to get
trapped there in the first place. Of course, if you
can get out, you can get it. And so what
that means is you can imagine as the Moon and
the Earth are all but in the common center of mass,
sixty degrees ahead and behind of the Moon are these
areas are space in the Moon's orbit that are like
little dimples in space where it's easy for stuff to
(35:05):
build up and get captured there temporarily before getting cleaned
out again. They're not deep enough for things to get
hooked there permanently. But what that means is interplanetary dust,
bits of the solar wind that aren't moving that quick
stuff splutted off the Moon by impact events, can some
of that can congregate there and spend a certain amount
(35:25):
of time there. Now, the dynamics of it as such
as been a lot of modeling done of this that
if dust is there for a reasonable amount of time,
it will actually get congregated into kind of bar features
and streams. I think you'll have to get a bit
of structure in it before it gets cleaned out. But
fundamentally what's going to be happening is that you've got
dust and gas getting temporarily captured there and then getting
(35:47):
cleaned out again, and so the amount of material there
will depend on what's happening at the time. These were
proposed a good long time ago, and they were first
kind of reported to be observed in nineteen sixty one
by Kordolowski. That's why they take that person's name and
got photos observe them with the naked eye. There are
about two magnitudes at that time fainter than the Gaganshine,
(36:11):
which is dust opposite the Moon in its orbit and
is visible as a very faint, fuzzy blob. So they're
very hard to pick up very hard spot. And for
many years after that other people looked for them and
could not see them, and that's where the controversy came
about that they're probably not there. The much more recent
observations by Hungarian astronomers made use of polar eimitary to
(36:32):
actually make these things easier to see, and they were
able to see them. Now there is I would have
thought some debate over whether these have been there permanently
since then, or whether what's happening is that the times
have been detected at times when the dust and gas
there has been a bit denser than normal, making them
easier to see. Yeah, because if this is a time
varying population of stuff there, there will be times when
(36:54):
you see more, times when you see less. And again,
PhD student and again it's just sick her over in
the US. She's talking with Aaron Bully possibly looking at
and doing some modeling of dust ejection from the Moon
and where it would end up, and some of that
dust would temporarily end up in the La Grande points,
become part of the cordialscia clouds, and then disperse again.
(37:16):
So the evidences that they're there, the evidences that they're transient.
The idea that there could be plasma there as well
is just better around the same physics of it being
an area which is like a little dimple where things
can build up and be held there for a little while.
And we're aware that when you've got a perfectly smooth floor,
the dust stays spread evenly, but if you've got any
little dimples and stuff like that, dust can build up
(37:37):
there until the gust of wind blows it out. It's
effectively what's going on there. So they're really interesting. It's
quite likely that all the other objects in the Solar
System would have things like this as well, So Mars's
Moon's Phobos and Demos. They're much less massive than our moon,
so the lagrange points won't be much tinier, but you
might get similar things there. We know that among the
(37:58):
boons of Second we've got a couple of co orbitals satellites,
including a couple of satellites that actually have Trojan companions.
It's not just Jupter and Neptune that have permanent trojans.
It's not just Earth and Mars, Saturn and Euros that
have temporary trojans. There are actually Trojan satellites in the
Saturnian system. And this is just one aspect of this now.
(38:18):
You know, you could imagine that in a very very
different world we could have had the moon and then
we could have had a couple of small satellites, one
leading it, one trailing. It's a bit and it's quite
possible that after the moon forming impact there may well
have been temporary kind of agglomerations of matter there on
a much more substantial level as the Moon was forming.
You can even have you know, small objects been accumulating
(38:40):
their forming there and then escaping and all the.
Speaker 2 (38:42):
Rest of it.
Speaker 4 (38:43):
But hopefully that covers stuff. It is a really fascinating topic.
Speaker 2 (38:47):
You know.
Speaker 4 (38:48):
The kind of imagery people have done to figure this
out back then was really challenging. You're talking about using
a very fast, wide angled lens and doing menthy exposures
to try and get a little bit of contrast between
the rightness of the sky where the clouds are and
the brightness of the sky.
Speaker 2 (39:03):
Where they aren't.
Speaker 4 (39:04):
The more recent work by the Hungarian team in twenty
eighteen did some very very clever stuff where then it
only imaged the clouds at the L five point when
they were there, and did the polarimetry, but they also
imaged the same part of the sky when the L
five point wasn't there. They also imaged it when there
were some high clouds like Cyrus there, when aircraft contrails
(39:25):
were passing through that area of the sky and things
like that, in order to have comparisons from other objects
that had in the past been suggested as giving false
positives here, and they were able to confirm that actually, no,
it was the presence of the L five point and
the dust there was what they got because it looked
sufficiently different to the other things that it was robust,
which is very very cool, And it's a good example
(39:46):
of when you're trying to find something that's incredibly hard
to see and hard to study, then you need to
do some really very impressive and very innovative observations to.
Speaker 2 (39:56):
Make that work.
Speaker 4 (39:57):
And you know, people have done some lovely modeling of
orbital connects to see how long things would reside there,
and there've even been proposals of sending spacecraft there to
check it out. But that's about where we sit with
them at the minute, and it is a fascinating subject.
We'll learn more in the years to come. Doubtless. When
Jessica's PhD is finished and she gets to go on
and do this further research, we'll learn a little bit
(40:19):
more about dust that is kicked off the surface of
the moon and where it goes and how that contributes.
But like everything, you know, there's more to learn than
we already have done, and we're still at the start
of this journey realistically.
Speaker 1 (40:30):
Yeah, yeah, absolutely, Yeah, great question and great to get
a question from our YouTube audience, which is ever growing.
Speaker 2 (40:37):
So thank you for.
Speaker 1 (40:38):
That, and we are done. Thanks for answering all those questions, Johnny.
Speaker 2 (40:43):
That's a pleasure.
Speaker 4 (40:44):
It's good to get some kind of brand teasers and
stuff that makes your head hurt a little bit.
Speaker 1 (40:48):
That does, doesn't it.
Speaker 7 (40:49):
Yeah, Yeah, I think we're Fred and I and now
yourself are constantly amazed by the depth of the inquisitiveness
of it audience.
Speaker 6 (41:00):
Yeah.
Speaker 2 (41:00):
I think that's a good way of just growing it.
Speaker 1 (41:02):
But all right, if you have questions for us, and
we could sure use some audio questions, we are thin
on the ground, jump on our website and send them in.
It's space Nuts podcast dot com or space Nuts dot Io.
Click on the AMA link at the top and you
can send text and audio questions to us that way
if you so desire, and don't forget to tell us
(41:23):
who you are or where you're from, or both. Thanks Johnny,
we'll catch you real soon.
Speaker 2 (41:29):
Thanks for having me, Always a pleasure.
Speaker 1 (41:31):
John ty Horner, Professor of Astrophysics at the University of
Southern Queensland here in the studio, couldn't be with us
again today. You got himself stuck another Grange point and
from me Andrew Dunkley, Thanks for your company. See you
on the next episode of Space Nuts. Bye bye, You'll
be to the Space.
Speaker 4 (41:49):
Nuts podcast available at Apple Podcasts, Spotify, iHeartRadio, or your
favorite podcast player.
Speaker 2 (41:58):
You can also stream.
Speaker 4 (41:59):
Onto Mare at fights dot com.
Speaker 1 (42:01):
This has been another quality podcast production from fights dot Com.
Hello again, thank you for joining us on Space Nuts
Q and A edition. This is where we answer audience questions,
or at least we read them out and pretend we
know what.
Speaker 2 (00:09):
We're talking about.
Speaker 1 (00:10):
Today we will be answering questions about dark matter versus
a black hole. It's a titanic struggle.
Speaker 2 (00:17):
Who would win.
Speaker 1 (00:19):
We are also going to discuss the demise of beetlejuice
or beetlegeis, depending on how you like to pronounce it.
We have a question about lagrange points and the Cordeleski
plasma clouds question has.
Speaker 2 (00:35):
Come up from a YouTuber.
Speaker 1 (00:37):
We'll deal with all that right now on Space Nuts.
Speaker 3 (00:40):
Fifteen second Channel ten nine ignition Squench Space Nuts or
three two.
Speaker 4 (00:53):
Space nuts as.
Speaker 5 (00:54):
And I reported Neils good.
Speaker 2 (00:57):
He's back again for more.
Speaker 1 (00:58):
Has done all the research, has all the answers to
all the questions, except for those four. It's Johnny Horner,
professor of astrophysics at the University of Southern Queensland.
Speaker 2 (01:07):
Johnny, Hello, I'm good afternoon.
Speaker 4 (01:09):
How are you doing.
Speaker 2 (01:10):
I'm all right.
Speaker 1 (01:10):
How are the renots going at your place?
Speaker 4 (01:12):
Well, not too bad. I think they've clocked off for
lunch at the minute, so we might get away with
it on I'm waiting for my other doctor insists I
pay attention to her. Are you yes?
Speaker 2 (01:21):
Dogs do that? Yes, indeed they do.
Speaker 1 (01:25):
All right, let's answer some questions. Firstly, we've got a
question from Howard. He said, first, I should say that
I think dark matter is going to end up as
a follergiston? Is that the word of our times?
Speaker 2 (01:41):
Sorry? Flodgist?
Speaker 1 (01:44):
Could be that of our times, a substance dreamed up
to resolve an otherwise unsolvable problem and later discarded as
science advances. But even so, here's my question. Since gravity
seems to be the only force that interacts with dark matter,
what happens when a black hole, the ultimate source of gravity,
comes into contact with dark matter? Does it eat it?
(02:06):
And if so, what happens? And if not, why not?
Speaker 2 (02:10):
I do?
Speaker 1 (02:10):
We've had questions of similar style and ilk before, and
I can't remember what Fred said, but I think it
said doesn't matter, you know, because dark matter? And yeah,
but I'm sure you've done your homework, because I didn't.
I never did homework as a kid, so why would
(02:31):
I start now?
Speaker 4 (02:32):
Well, there seems to be evidence that homework is fairly pointless. Such, yes,
my Apartner's a primary teacher, and you know, I think
if she had her where, kids wouldn't have any homework,
and at least until you're fairly well through secondary school,
it doesn't seem to serve a purpose other than making
some parents feel like their kids are getting properly worked,
you know. So, but onto something that I actually have
(02:54):
expertise in, rather than being talking about teaching what I
clearly done that much, is a real interesting one. It's
I get what you mean with the flogist, and I
think possibly dark energy, i'd argue, is a bit more
of a flogist and thing than that matter at this stage,
because it's very clear that there is mass out there
(03:14):
that it's having an effect but we can't see. And
that's fundamentally what dark matter is. We can add up
all of the mass of all of the things that
we can see in the forms of dust and gas
and stars and all the rest of it, and the
gravitational pull within galaxies, particularly as you get further out
into galaxies, is more significant than can be explained by
(03:34):
the luminous material art and that's where dark matter comes from,
and we see its effects even if we don't see
it in I guess just the same way as back
in the eighteen hundreds, astronomers saw the effects of Uranus
of Neptune's gravity perturbing the orbit of Uranus as it
went round the Sun, and we detected Neptune indirectly. And
(03:55):
then people said, only point you tell it's goope here,
because it must be a planet in this part of
the sky pulling Urinus around and low, and behold, we
found it. And this is fairly fundamental to me as
an exoplanet science person, in that the vast majority of
planets we found around o the cells we found indirectly.
We see a star doing something unexplained, We see it
winking or we see it wobbling, and we in further
(04:17):
presence of a planet as an explanation for that unexplained behavior.
And when you rule out all the other explanations, someone
that's left as a planet, and Bob's your uncle. You've
added one to the Italian. Like we said in the
earlier episode, we've now passed six cells, and so whoopy
for us, we're doing really well. So there's a lot
of evidence that dark matter is a thing, and what
it is nobody really knows. There's been a lot of speculation,
(04:40):
but what seems to be the case is that dark
matter is something that interacts through gravity but doesn't interact
with anything else. It doesn't interact with light. It doesn't
impede light because we see dust blots light, so dust
is not dark matter. So what happens, Well, if dark
matter interacts with gravity in just the same way as
normal matter, then it will interact with a black hole
(05:02):
in almost the same way as normal matter. And they
almost said a little asterisk. I'll come to in a minute.
What that means is that if something gets close enough
to a black hole to be within its event horizon,
then that means it would have to travel faster than
the speed of light to escape from the gravitational pull
of the black hole. So it's effectively been nombed. And
you've got black holes being the pack man of the
(05:23):
universe that just go around gobbling everything up. Once it
is gobbled up, it doesn't matter if it's dark matter
or normal matter. It's been nombed and it just adds
to the mass of the black hole. And I guess
the black hole is a bit like the ball, and
it's your individuality. Indistinctiveness has been added to our own
and the dark matter has been nombed in just the
same way it would have been with normal matter. So
(05:44):
from that point of view, there is actually no problem.
We'd expect dark matter to be eaten and to stay eaten.
There are suggestions that the supermassive black holes like the
one we've got at the middle of the Milky Way
are only able to be formed if that matter exists,
and even more normal mass black holes have a restriction
(06:08):
on the amount that they can eat. It's almost like
the celestial equivalent of a gastric band or something like that.
It's something called the Eddington limit. Material falling into a
black hole, that is normal matter as it falls in
gets accelerated, gets heated up in its light. And if
you've got a black hole eating a lot of stuff,
(06:28):
there's a lot of material falling and emitting incredible aunts
of radiation. They can essentially push away or the matter
around the black hole and force it to stop eating,
effectively putting a limit on the amount that it can
devour at any given time. And you do get things
that are eating at what's called super Eddington rates, but
(06:49):
that's where something's essentially pushing material in so quickly that
it overcomes that effect. So I guess it's a bit
like saying you can only drink so much water because
you can only swallow so much. But if somebody shoves
a fire hose in your mouth, the water's going to
go somewhere. That's kind of that situation. But that puts
a limit on how much a black hole can eat
(07:10):
at a given time. At the pace at which can
devour matter, dark matter doesn't interact with like al radiation
or anything like that, so the Eddington limit doesn't apply
because a black hole shining like a searchlight will not
impede the motion of dark matter one little bit. And
so there is an idea that actually dark matter is
a more effective food for black holes and normal matter
(07:34):
because dark matter circumvents the Gasrick band. It circumvents this
Eddington limit that prevents a black hole from eating to excess,
and that may actually have been a significant part of
how the supermassive black holes that we get in the
middle of galaxies actually got their start where they got
their start aided by dark matter. And so it's a
(07:55):
really interesting question because I had not really thought of
this until Howard's question. Came through and added a bit
of reading around. But it's actually one of these scenarios
where dark matter, it seems, is a help to black
holes rather than a hindrance, and therefore may help to
explain why the universe is and where that we see
it today, beyond just explaining the rotation curves of galaxies
(08:17):
and things like this, which is why it was hypothesized
in the first place.
Speaker 1 (08:20):
Okay, so you do believe there's interaction between dark matter
and black holes.
Speaker 4 (08:25):
Of course, Yeah, and sorry, of course the sounds to dismissive.
The reason that it's in, of course, is that dark
matter interacts with gravity. That's fundamentally how we found it
in the first place. And therefore, if it falls into
a black hole, it behaves like any other kind of
matter from the point of view gravity.
Speaker 2 (08:46):
And so therefore, and I.
Speaker 4 (08:47):
Mean, there are some suggestions that black holes are a
significant component of dark matter.
Speaker 2 (08:53):
Yes, we can only see them when they're feeding.
Speaker 4 (08:55):
If they're not eating anything, we have no indication of
black holes there other than its effect on the mass
around it. You know, light gets bent around it and
all the rest of it. Yeah, some component of dark
matter may well be primordial black holes. That's one of
a suggestion.
Speaker 1 (09:09):
Yeah, there's still so much to learn. We don't know
much at all, although they also I think if I
recall correctly say that dark matter clusters in around galaxies
and around concentrated points, it's much thinner where the universe
is emptier.
Speaker 2 (09:28):
Is that right?
Speaker 4 (09:30):
And that kind of makes sense as well, because if
dark matter is feeling the effects of gravity like everything else,
the same things that would have pulled an excess of
visible matter together to farm galaxies would have brought together dark.
Speaker 2 (09:41):
Matter as well.
Speaker 4 (09:42):
And there is this discussion that galaxies have dark matter
halos around them. So the rotation curves of galaxies are
evidence for dark matter within those galaxies, meaning that there
is more mass interior to a certain distance from the
middle of the galaxy than we can account for by
what we see. That means that together rotation happening quicker
because it's more master left on, more gravitational pulse or
(10:03):
faster rotation. But the massive galaxy clusters, in terms of
how the galaxies are interacting with each other and how
they're moving within the clusters, the mass within the cluster
has to been bigger than the masters that the galaxies
seem to have from the visible material, even accounting for
the dark matterrhithm causing their rotation speeds to be higher.
(10:24):
And that's suggesting that that matter is also in a
halo around the galaxy, given that galaxy even more muster
even more.
Speaker 2 (10:32):
Yes, it is so fascinating.
Speaker 1 (10:35):
And Flogiston was a hypothetical fire like element once thought
to be contained within combustible bodies and released during combustion,
a theory proposed by Johann Beecher, and it's an outdated
theory that was eventually disproved by Antoine Levosier through his
experience with oxygen, which demonstrated that burning is a chemical
(10:56):
reaction involving the combination of a substance with oxyde, not
the release of flogiston. There you are, all right, Howard,
Thank you so much for a great question. Let's take
a break from the show to tell you about our sponsor,
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Speaker 2 (12:36):
Now back to the show.
Speaker 1 (12:38):
Three space nuts now. Gary is next. He's a fan
from Canada's East Coast. I was only recently on Canada's
East Coast, visited Peggy's Cove and Halifax and lovely part
of the world. He goes on to say, I enjoy
your humor mixed with actual scientific knowledge out of part's
(13:00):
probably not anyway. Question, can you tell me if beetlejuice
Beetlegeiss explodes six hundred and eighty million light years away,
whether we are just seeing something that happened six hundred
and eighty million years ago, traveling at the speed of light.
Speaker 4 (13:17):
It's a really good question. It comes a plot when
I'm doing outreach and stuff like that. Beetlejuice is depending
on whose measurements you expect, it's not quite six hundred
and eighty million light years away. It's somewhere between about
five hundred and seven hundred light years away, so it's
a bit closer to home than that. But the question
still stands. When we see objects in the universe, we
(13:39):
see them as they were when the light was emitted
from them, and that's even true for the rumor around you.
It's just that everything nearby is cell class that you're
effectively seeing instantaneously. Light travels at three hundred thousand kilometers
a second, so we see the moon, which is about
three hundred and eighty four thousand kilometers away, worrying. We
(14:00):
just had all the fuss about the supermoon's yet again.
So the distance to the Moon does very a little bit,
but that means we see the Moon using light that
reflected off the surface of the Moon about one and
one third seconds ago. It's one and one third light
seconds away. We see the Sun with light that left
the surface of the photosphere a bit more than eight
minutes ago. And so when you see anything, you're seeing
(14:24):
light that left a period of time ago. You see
everything as it was in the past, rather than as
it would be in a perverse now that if you
could teleport there instantaneously, it would look different. I mean
that brings into question could you teleport at faster than
the speed of light? But then the question is kind
of teleport anyway, So that's getting getting into the grounds
(14:44):
of science fiction. But it brings open a odd philosophical
kind of question, which is what do you define as
something happening now? Do you define them now as a
perceived now where you are, or do you find now
as being the time that the event happens, that the
(15:06):
light would reach you once it has traveled that business
to get to you. And I'm explaining that badly. But
this is essentially the fundamental of the question. If Beetlejuice
exploded a thousand years ago, on that light reaches as say,
three hundred years in the future, So it turns out
it was seven hundred light years away. Beetlejuice exploded a
(15:27):
thousand years ago, the light travels for seven hundred years,
so it all reaches in three hundred years seven. I'm
sure my head has got flipped over there somewhere. But
on if Beetlejuice exploded a thousand years ago, we saw
it three hundred years in the future, then that'd be
thirteen hundred light years away. That's I'm going the wrong way.
But anyway, we know, if you have exploded in the past,
we see it at some point in the future. Did
(15:49):
that explosion happen in the past of the future? Well,
in Beetlejuice's frame of reference, if you were stood camping
near Beetlejuice, you would have seen it in the past.
You'd have seen it happen already. But any signal you
sent to tell us that it had have happened would
only just arrive at the same time that the explosion did,
because you'd have to see it first, and then the
signal back. So from the point of view of us
(16:11):
here on Earth, when does beetlejuice explode? Is it when
we see it or when we calculate back how long
ago that explosion had to happen for us to see
it today. And it's where we get into the philosophy
of perception and what it actually means to be now,
because everything around us, even the tip of my own nose,
(16:31):
is far enough away that I'm seeing it in the past.
I mean, I'm seeing it in the past by nane
oh seconds, but it's still in the past. And so
there's a weird bit of internal philosophy that has to
go on there that is driven by the size of
the universe. And we came up with this fine with sound.
We see a flash of lightning and then we hear
(16:53):
a rumble of thunder a certain amount of time later,
and we're aware that the two events happened at the
same time, but the sound takes a certain amount of
time to reach us. So if we imagine that there
was some form of instantaneous communication that could happen that
happened faster than the speed of light, and we were
able to have a real ay near beetlejuice. Tellers, beetlejuice
(17:14):
has now gone back, you will see it in seven
hundred years time. Then it makes sense to say that
beetlejuice ex blooded in the past and we only see
it now. But from your perception point of view, you'd
see it happening now when you saw it happen now,
and that will be all now. And so this is
a really fun question because the reality is that it's
(17:35):
all to do with frames of reference and where you stand.
And yeah, I'm listening to a fairly pulpy science fiction
series at the minute called Expeditionary Force that actually talks
about how slow light is when you're having combat happening
in space. You know, if you're shooting lasers and mazers
that people neural lights second away from them. By the
time your laser gets there, they'll have moved, so you've
(17:58):
got to shoot whether going to be not whether they
actually are, but then they know that, so they're dodging.
And the further away you are, the longer it takes
for the light to reach you. So you've got the
bisarre thing of if you can jump through space and
you can go through a wormhole and pay someone else.
You could fight someone and then jump through space and
watch the battle happen and watch yourself fight them.
Speaker 2 (18:17):
Wow.
Speaker 4 (18:17):
And this is where all the philosophy starts to mess
with your head. But it makes for wonderful science fiction
scenarios so long as you build something into your science
fiction world that allows you to have faster than light
travel so you can get ahead of the images of
yourself doing a certain thing.
Speaker 1 (18:34):
That is really interesting. I love science fiction for that
reason because you can just make all this stuff happen
that it is not yet achievable as far as we know.
Speaker 4 (18:43):
There must be is our example. So that when I
was young, I remember the Anne McCaffrey novels really well.
And you know, she was most famous across for the
Dragons series. You know, all the books about people in
a world where they live and bond with dragons and
they burned thread from the end, it turns out that
it's actually a soft sci fi setting rather than a
fantasy setting because reasons you find further down the series.
(19:04):
But she also had a series of books about the
Talents of Earth, which were these people with psychokinetic and
telepathic talents who could transport things using the power of
the mind from one place to one other, and they
could communicate telekinetically. And of course what you do with
people like that in Aan McCaffrey's world is not turn
them into soldiers and warriors like Marvel or the X
Men would do it, but you turn them into the
(19:26):
postal service, and the people effectively become the method by
which we send people to other stars. And if you're
a powerful enough telekinetic, you can pick something up on
Earth and send it to Capella and it'll appear there.
But then they had really powerful telescopes, and they have
had to be really powerful telescopes the first time they
tried sending things to another star, and they'll look at
(19:46):
that start and psychic person goes wibily wobbly, whibly wobbly,
and the thing disappears, and then it appears x to Capella,
and that's all well and good until somebody points out
the fact that the light was seeing from Capella left
it thirty years ago and we've just seen that thing arrive,
so they've obviously teleported it back through time. And then
you end up with this bizarre world where you've got
(20:07):
this web of world's vast distances from each other that
are linked by these postal service workers effectively, who can
from an instant communication instant transportation. But in order to
have it the instant and to maintain the current, now
they've had to send things back in time. But that
that means if they send them back in time, but
(20:28):
they can communicate instantaneously in both directions, could they tell
you thirty years ago to not send them.
Speaker 5 (20:34):
Yeah, it's a similar story in terms of the Dune
sci fi series, because same thing.
Speaker 1 (20:44):
They fold space, so you can go instantly from one
planet to Dune. But it's based on what you just said,
that's not the case. They'd have to be going back
in time as well.
Speaker 4 (20:58):
Yeah, and the un stuff got that part right. But
then you do have that thing of if it can
communicate instantaneously both ways, then you're communicating back in time
by thirty years. But if they then looked back at Earth,
they would see Earth as it was sixty years earlier,
except thirty years back in time. Looking back thirty years,
it strikes me that with big enough telescopes that would
(21:20):
I mean, it's a science fiction world, so we've already
broken the laws of physics. But you would make detective
work and police work totally redundant, because what you do
is you'd say there was a crime last night, Right,
we'll teleport someone fourteen hours away so they're looking back
twenty eight hours, so they can just look back and
see what happened.
Speaker 1 (21:38):
Yes, yeah, it makes I love I love it.
Speaker 2 (21:43):
I love these impossible scenarios.
Speaker 1 (21:47):
But you know, one day they might come up with
a way of doing some weird stuff that we can't
explain today, and there'll be some logic attached to it.
Speaker 4 (21:56):
But I'm sure if we were podcasting one hundred and
twenty five years ago, people will come so he couldn't
have a heavier heavier than their flight, and look how
that worked out.
Speaker 1 (22:04):
Yeah, exactly, all right, Thank you Gary. Hopefully we covered
that question for you. This is Space Nets with Andrew
Dunkley and John y Jonna. Okay, we take all for
space Nuts. Next question, Oh, we're still in Canada. This
question comes from Mark.
Speaker 6 (22:26):
Hi. It's Mark in London and Canada. I'm current listening
to all the back episodes, so I'm in March twenty
twenty one, so if you answer my question, it might
take me a while to hear it. But I was
wondering about lagrange points and the way they're describe as
a gravitational well, and we can send satellites there to
(22:51):
orbit around them.
Speaker 1 (22:52):
Is there a way to.
Speaker 6 (22:54):
Define the mass of the lagrange point? Like, obviously there's
nothing there, it doesn't atch you have a mass, but
we define or we observe things orbiting, and we can
define the mass of all those objects. So when you
see a satellite or design a satellite to go into
orbit around a lagrange point, is there an equivalent mass
(23:18):
that it's orbiting. That's obviously created by the whole system
of the larger objects, But is that does that mass?
Is it definable? Thanks Gat, Thank you Mark.
Speaker 1 (23:32):
So Mark's actually demonstrating time travel. He's listening to us
in the past, but we're hearing him today.
Speaker 4 (23:39):
I was just thinking of that. So the question is
when Mark listens to this answer, is he listening to
in twenty twenty five or twenty twenty nine.
Speaker 1 (23:46):
H's that's a good point, very interesting, and yeah, thanks
for the question, Mark. So we're looking at lagrange points.
Speaker 2 (23:55):
Our next question actually kind of focuses on that as well.
Speaker 1 (23:59):
Lagrange point points, gravitation wheels, the mess of a lagarage
point I think was the gats of his question.
Speaker 4 (24:06):
And it's a really interesting question. In fact, I've got
a pH d student, part time student working with me
who asked a very similar question a couple of months ago,
because he's going to be working and looking at the
Nettune Trojans, which are trapped around the L four and
L five O the grand points of Neptune, and they're
library around following this kind of kidney shaped path over
a period of hundreds of years around this point sixty
(24:28):
degrees ahead or behind Neptune.
Speaker 2 (24:29):
And it so, but.
Speaker 4 (24:31):
What's going on here is, well, take a little bit
of a deeto. When I was a kid, I was
a member of the Scouts, and me too. When you
were in the Scouts and you went walking around the countryside,
you had an Ordermance survey map. And I don't know
if that's called the same thing overseas, but that's what
it was in the UK. And what this map had
was a map of all the roads and all the
hills and all the rest of it, but drawn on
(24:53):
it were contours, and all points on a given contour
were the same height.
Speaker 2 (24:57):
Above sea level yep.
Speaker 4 (24:58):
And so you could tell how told the hills will
how seep the valleys where all the rest of it.
What those maps actually are are maps of gravitational potential.
So all objects at the same distance from the center
of the Earth have the same gravitational potential, and you
join them up with a contour that's exactly the same thing.
So if you make a hypothetical simplified solar system where
(25:20):
you just have the Earth while the Earth and the
Moon's mush into one and the Sun and nothing else,
you can make a contour map where you measure where
you calculate the gravitational potential every location in the solar system,
and then you do the same kind of map. You
join the points that have the same gravitational potential by
a contour, and you get a contoon map, and that
(25:44):
is fundamentally the same as your ordinan survey map. Points
that have the same gravitational potential will be metaphorically at
the same altitude above sea level, same distance above sea
level as a solar system. Now, if you draw a
line directly between the Sun and the Earth, the Sun
is at the bottom of an enormous blooming hole. You know,
(26:04):
the contours are circular around it. The Earth is at
the bottom of a smaller hole, and this is where
the whole metaphor of weights on a rubber sheet bowing
the rubber sheet comes from. So the Earth is at
the bottom of its own hole that is smaller than
the hole that the Sun makes. And so if you
have a line between them, you effectively come up all
from the Sun until you reach a certain point, and
(26:24):
then you tip over and you sat falling down the earthshole.
So you go downhill again. So between the two you've
got like a saddle point where at the top of
that saddle you're at a flat point where s basically
gravitational potential is flat and you could balance, Say you
could put a marble there and it would sit there.
But if that marble goes slightly off in either direction,
it'll roll down the hill.
Speaker 2 (26:44):
So if you get a.
Speaker 4 (26:45):
Little bit closer, then you'll fall off and roll towards
the Sun. If you get a little bit closer to
the Earth, you'll roll off and roll towards the Earth. Now,
if you move out from two dimensions between the Earth
and some three dimensions, if you roll clockwise or anti
clockwise away from that saddle point, you'll actually be trying
to roll uphill, so you'll fall back down into it.
So you've got this kind of really is like a
(27:07):
saddle point, where towards the Sun and towards the Earth
you fall downhill, but at right angles to that you
try and roll up hill. So you've got this local
flat area where if you move a little bit ahead
or behind it in your orbit, you'll roll back down.
So you've got a bit of a restoring force there,
but if you roll inward or outward.
Speaker 2 (27:25):
You'll fall off the hill.
Speaker 4 (27:27):
And that's why that lagrange point is an unstable one.
It's like a saddle point. And the three lagrange points
that are on the line between the Earth and the Sun,
L one, which is between the Earth and the Sun,
L two, which is on the far side of the
Earth beyond the Earth but on that line, and L three,
which is on the far side of the Sun opposite
the Earth. Yeah, those points are all these kind of
(27:49):
saddle points, so they're a bit more stable than normal
space because you can imagine balancing on the flat part
of the hill, but if you roll in either direction,
you fall away. Now a lot of there are spacecraft
sit at the inner or the outer lagrange point L
one or L two. The ones at L one sit
there because they can observe the Sun and give us
prior warning if something's coming our way cell a mass ejection,
(28:10):
something like that. The ones at L two sit there
to be in a good position to observe space, but
have station keeping with the Earth. They move around with
the Earth, and that seems like the James Web Space telescope.
But because those locations are these kind of saddle points,
they're not perfectly stable. Those spacecraft have to have fuel
to stay on stations, so if they start to drift downhill,
they can push themselves back up and get back to
(28:33):
the saddle point. And they actually do this by wabbling
and librating around that point and have a little orbit.
The other two lagrange points are L four and O five,
or sixty degrees ahead and behind the Earth in its
orbit around the Sun, and these are like enormous flat plateaus.
If you look at a contour map of the gravitational
potential of the cell system, you get these big kidney
(28:53):
shaped areas that are pretty flat, and that means if
you have your ball there, it could just sit there,
even if you're quite a long way away from the
center point of that lagrange point. You'd sit on one
of these contours, and if you start to roll, you'd
follow the contoe around, and you'd follow this kind of
kidney shipped path, staying trapped around the lagrange point but
vibrating around it. And they're like plateaus, so they're much
(29:16):
more stable than the kind of saddle points, and that's
why those are the points which in the outer Solar
System have huge populations. In the orbit of Jupiter, have
big populations in the orbit of Neptune. Those are the
Juter and Neptune trojans. The other planets can have trojans too,
but they tend to be temporary because the Solar System
is not simply three objects, it's actually got all the planets.
(29:38):
So if you're sadden near the lagrange points of Earth,
you're getting gravitational pulls from Venus and Mars nearby, from
Jupter and all the other planets as well, and eventually
they'll pull you off the stable plateau and you'll fall away,
so you'll only live there temporarily. Yea. But for Jupter
and Neptune, those planets are so dominant compared to the
other things around. They can hold things permanently at the
least Lagrange points, and the motion of a objects at
(30:00):
the alpha and l five points is that over hundreds
of orbits, they we'll gradually librate around that alphour point,
so they'll be on average sixty degrees our head or
behind the planet, but they'll be moving around that and
they'll be orbiting it. So the concept of trying to
think about whether you can define a mass at the
center of the la Grange point that holds them is
not quite the physics that's going on. That librating around
(30:24):
that point only works if you're in a frame of
reference that is rotating with the orbit of the planet.
So you're let's imagine we're looking at the Jupiter trojans.
You imagine you somehow suspended above the plane of the
Solar System, lying there, watching all the objects in the
Solar System, and you're spinning once every twelve years, just
as Jupiter orbits are some once every twelve years. So
(30:45):
from your point of view, Jupiter and the Sun stain
exactly the same place in your field of view. And
then over much longer time scales of hundreds of years,
these trojans would appay to orbit thet lagrange point. I
guess you could if you wanted to try and construct
some more to visualize that way. You imagine that there
is a virtual mass at the Vela Grange points, and
that's what the trogans are orbiting while they'll librate. It
(31:08):
would have to be a spread out mass because if
it was a point mass, they'd have much more circular orbits,
they wouldn't have these kidney shaped things, so the Masso'd
have to be spread out. But you could, I guess,
visualize it and calculate it, but that would only be
valid in the rotating reference frame, which is a bit
of a conceit anyway. In the normal scheme of things,
(31:29):
where everything's rotating around and you're not spinning above watching it,
these objects are moving on orbitstead of very similar period
to say Jupiter, but slightly longer, slightly shorter, and as
they pull if it's a slightly short orbital period than Jupiter,
gradually they'll insure head of Jupe to get further and
further ahead. Eventually they drift outwards and they're now further
from the Sun, so they're now going around the Sun
(31:51):
slower than Jupiter. And they sat fall back towards it
until Jupiter's gravity tweaks them and they fall inwards a
better than they start moving quicker. So it's actually all
down to the traction between Ju to the Sun and
the object in that case, rather than a virtual mass
off there. So I can see what you're thinking about,
and I can see it as being something that is
a good model to help you visualize what's going on,
(32:13):
But it's not the kind of thing we do calculations of,
and I don't think it's a sufficiently advanced mental model
that you'd want to get to that level with because
it starts taking down a rabbit hole of the physics
doesn't actually work that way, and you can put yourself
in traps when you do that. But it is a
really nice way to visualize initially how it works. It's
(32:35):
if you're librating around one of the lagrange points, it
is as though there is a force keeping you trug
to it. So it's as though there is a mass there,
keeping attracting you towards the lagrange point. It's just that
that isn't actually a mass there. It's simpler to do
with the intraction of all the other objects floating around
that create that virtual thing that keeps you locked around
(32:55):
that place.
Speaker 1 (32:56):
M hm okay ho'pefully then helped you out, Man.
Speaker 4 (33:02):
Broad piece MutS.
Speaker 1 (33:05):
And our next question and our final question kind of
relates to this question that Mark raised, And this came
from a YouTuber. I don't know their name, but that's okay.
Can you do a deep dive on the Cordleski plasma
clouds or do we not have much information on these
strange things now I look them up. The Cordleski or
(33:29):
Cordleuski clouds are two large, tenuous dust clouds located at
L four and L five lagrange points of the Earth
Moon system. Originally predicted in the nineteen fifties, first spotted
in the sixties, their existence was long doubted, but recently
confirmed in twenty eighteen by observations using a polarizing filter
that detected reflected sunlight from the dust. While they are
(33:53):
called dust clouds, summary research suggests they are a complex
a complex form of dusty PLASMI ah, yes.
Speaker 4 (34:01):
So this is a fascinating question. The Koondleshki clouds are transient,
and I think that's probably part of why they've been
hard to confirm because there are areas where as we
just described those lagrange points. If you only have the
Earth and the Moon in space and nothing else, then
the leading alpha and OL five lagrange points of the
(34:22):
Moon could be stable on million year, billionaire time scales.
But in actuality in the system where you've got the Sun,
you've got all the other planets, and for small objects,
the influence of the solar wind and the Sun's radiation
becomes significant as well. What that means is that it
becomes easier to escape from those lagrange points. By being
(34:43):
easier to escape, it also means it's easy to get
trapped there in the first place. Of course, if you
can get out, you can get it. And so what
that means is you can imagine as the Moon and
the Earth are all but in the common center of mass,
sixty degrees ahead and behind of the Moon are these
areas are space in the Moon's orbit that are like
little dimples in space where it's easy for stuff to
(35:05):
build up and get captured there temporarily before getting cleaned
out again. They're not deep enough for things to get
hooked there permanently. But what that means is interplanetary dust,
bits of the solar wind that aren't moving that quick
stuff splutted off the Moon by impact events, can some
of that can congregate there and spend a certain amount
(35:25):
of time there. Now, the dynamics of it as such
as been a lot of modeling done of this that
if dust is there for a reasonable amount of time,
it will actually get congregated into kind of bar features
and streams. I think you'll have to get a bit
of structure in it before it gets cleaned out. But
fundamentally what's going to be happening is that you've got
dust and gas getting temporarily captured there and then getting
(35:47):
cleaned out again, and so the amount of material there
will depend on what's happening at the time. These were
proposed a good long time ago, and they were first
kind of reported to be observed in nineteen sixty one
by Kordolowski. That's why they take that person's name and
got photos observe them with the naked eye. There are
about two magnitudes at that time fainter than the Gaganshine,
(36:11):
which is dust opposite the Moon in its orbit and
is visible as a very faint, fuzzy blob. So they're
very hard to pick up very hard spot. And for
many years after that other people looked for them and
could not see them, and that's where the controversy came
about that they're probably not there. The much more recent
observations by Hungarian astronomers made use of polar eimitary to
(36:32):
actually make these things easier to see, and they were
able to see them. Now there is I would have
thought some debate over whether these have been there permanently
since then, or whether what's happening is that the times
have been detected at times when the dust and gas
there has been a bit denser than normal, making them
easier to see. Yeah, because if this is a time
varying population of stuff there, there will be times when
(36:54):
you see more, times when you see less. And again,
PhD student and again it's just sick her over in
the US. She's talking with Aaron Bully possibly looking at
and doing some modeling of dust ejection from the Moon
and where it would end up, and some of that
dust would temporarily end up in the La Grande points,
become part of the cordialscia clouds, and then disperse again.
(37:16):
So the evidences that they're there, the evidences that they're transient.
The idea that there could be plasma there as well
is just better around the same physics of it being
an area which is like a little dimple where things
can build up and be held there for a little while.
And we're aware that when you've got a perfectly smooth floor,
the dust stays spread evenly, but if you've got any
little dimples and stuff like that, dust can build up
(37:37):
there until the gust of wind blows it out. It's
effectively what's going on there. So they're really interesting. It's
quite likely that all the other objects in the Solar
System would have things like this as well, So Mars's
Moon's Phobos and Demos. They're much less massive than our moon,
so the lagrange points won't be much tinier, but you
might get similar things there. We know that among the
(37:58):
boons of Second we've got a couple of co orbitals satellites,
including a couple of satellites that actually have Trojan companions.
It's not just Jupter and Neptune that have permanent trojans.
It's not just Earth and Mars, Saturn and Euros that
have temporary trojans. There are actually Trojan satellites in the
Saturnian system. And this is just one aspect of this now.
(38:18):
You know, you could imagine that in a very very
different world we could have had the moon and then
we could have had a couple of small satellites, one
leading it, one trailing. It's a bit and it's quite
possible that after the moon forming impact there may well
have been temporary kind of agglomerations of matter there on
a much more substantial level as the Moon was forming.
You can even have you know, small objects been accumulating
(38:40):
their forming there and then escaping and all the.
Speaker 2 (38:42):
Rest of it.
Speaker 4 (38:43):
But hopefully that covers stuff. It is a really fascinating topic.
Speaker 2 (38:47):
You know.
Speaker 4 (38:48):
The kind of imagery people have done to figure this
out back then was really challenging. You're talking about using
a very fast, wide angled lens and doing menthy exposures
to try and get a little bit of contrast between
the rightness of the sky where the clouds are and
the brightness of the sky.
Speaker 2 (39:03):
Where they aren't.
Speaker 4 (39:04):
The more recent work by the Hungarian team in twenty
eighteen did some very very clever stuff where then it
only imaged the clouds at the L five point when
they were there, and did the polarimetry, but they also
imaged the same part of the sky when the L
five point wasn't there. They also imaged it when there
were some high clouds like Cyrus there, when aircraft contrails
(39:25):
were passing through that area of the sky and things
like that, in order to have comparisons from other objects
that had in the past been suggested as giving false
positives here, and they were able to confirm that actually, no,
it was the presence of the L five point and
the dust there was what they got because it looked
sufficiently different to the other things that it was robust,
which is very very cool, And it's a good example
(39:46):
of when you're trying to find something that's incredibly hard
to see and hard to study, then you need to
do some really very impressive and very innovative observations to.
Speaker 2 (39:56):
Make that work.
Speaker 4 (39:57):
And you know, people have done some lovely modeling of
orbital connects to see how long things would reside there,
and there've even been proposals of sending spacecraft there to
check it out. But that's about where we sit with
them at the minute, and it is a fascinating subject.
We'll learn more in the years to come. Doubtless. When
Jessica's PhD is finished and she gets to go on
and do this further research, we'll learn a little bit
(40:19):
more about dust that is kicked off the surface of
the moon and where it goes and how that contributes.
But like everything, you know, there's more to learn than
we already have done, and we're still at the start
of this journey realistically.
Speaker 1 (40:30):
Yeah, yeah, absolutely, Yeah, great question and great to get
a question from our YouTube audience, which is ever growing.
Speaker 2 (40:37):
So thank you for.
Speaker 1 (40:38):
That, and we are done. Thanks for answering all those questions, Johnny.
Speaker 2 (40:43):
That's a pleasure.
Speaker 4 (40:44):
It's good to get some kind of brand teasers and
stuff that makes your head hurt a little bit.
Speaker 1 (40:48):
That does, doesn't it.
Speaker 7 (40:49):
Yeah, Yeah, I think we're Fred and I and now
yourself are constantly amazed by the depth of the inquisitiveness
of it audience.
Speaker 6 (41:00):
Yeah.
Speaker 2 (41:00):
I think that's a good way of just growing it.
Speaker 1 (41:02):
But all right, if you have questions for us, and
we could sure use some audio questions, we are thin
on the ground, jump on our website and send them in.
It's space Nuts podcast dot com or space Nuts dot Io.
Click on the AMA link at the top and you
can send text and audio questions to us that way
if you so desire, and don't forget to tell us
(41:23):
who you are or where you're from, or both. Thanks Johnny,
we'll catch you real soon.
Speaker 2 (41:29):
Thanks for having me, Always a pleasure.
Speaker 1 (41:31):
John ty Horner, Professor of Astrophysics at the University of
Southern Queensland here in the studio, couldn't be with us
again today. You got himself stuck another Grange point and
from me Andrew Dunkley, Thanks for your company. See you
on the next episode of Space Nuts. Bye bye, You'll
be to the Space.
Speaker 4 (41:49):
Nuts podcast available at Apple Podcasts, Spotify, iHeartRadio, or your
favorite podcast player.
Speaker 2 (41:58):
You can also stream.
Speaker 4 (41:59):
Onto Mare at fights dot com.
Speaker 1 (42:01):
This has been another quality podcast production from fights dot Com.
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