Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Dwarf Planets, Peculiar Moons & the Mystery of Dark Matter

Transcript

Dwarf Planets, Peculiar Moons & the Mystery of Dark Matter · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Andrew Dunkley: Hi there. Thanks for joining us. Andrew
0:01
Dunkley here. Ah, this is Space Nuts,
0:04
where we talk astronomy and space science.
0:07
Thanks for joining us. Coming up on this
0:10
episode, lots, to talk about and really
0:12
interesting stuff for a change. No, as usual.
0:15
and this one, I saw and thought, gee,
0:18
we got to talk about this because we're
0:20
always looking for something in the outer rim
0:23
of the solar system and now we may have
0:26
found something and it's not planet nine. In
0:28
fact, it's possibly a new dwarf planet,
0:31
which could mean there is no planet nine.
0:34
Interesting. there's a peculiar moon,
0:37
orbiting Saturn, known as Iapetus. And
0:40
it's starting to get attention again.
0:42
We'll tell you why. And
0:45
primordial black holes. Yep. And
0:48
the fact that they might be today's dark
0:51
matter. Is that a matter we should discuss?
0:54
Damn right it is. And we'll do m it.
0:57
Do it right now on, Space nuts.
0:59
Voice Over Guy: 15 seconds. Guidance is internal.
1:02
10, 9. Ignition
1:05
sequence start. Space nuts. 5, 4, 3,
1:08
2. 1. 2, 3, 4, 5, 5, 4,
1:11
3, 2, 1. Space nuts. Astronauts
1:14
report it feels good.
1:15
Andrew Dunkley: And despite his premature announcement,
1:19
he officially welcome Professor Fred Watson
1:21
Walton at large. Hello.
1:23
Professor Fred Watson: Thank you for that. Yes, I do apologise for
1:25
being there before. I'm, forgetting that I
1:27
have to be formally introduced before I,
1:29
Andrew Dunkley: More good.
1:30
Professor Fred Watson: Yes, yes.
1:31
Andrew Dunkley: Before, that's how I used to run my radio
1:33
show. I didn't care what happened if some. If
1:35
someone walked in. They were just part of the
1:37
show. I didn't, you know, I
1:40
never cared about standing on ceremony or,
1:43
or, you know, sticking to the rules of radio.
1:46
What rules? I mean, it's just people talking,
1:49
isn't it? And playing music and enjoying
1:50
themselves. I thought
1:53
that's how I ran. Even when I worked for the
1:56
nc, I was.
1:57
Professor Fred Watson: I was like, that's right.
1:59
Andrew Dunkley: I've been dropped for it a few times. But
2:01
eventually they saw. They saw the light and
2:03
started going, hang on a minute. Listening
2:06
to this bloke. We might. We might be onto
2:09
something. anyway, they eventually brought in
2:11
an expert to teach us how to be human beings
2:14
on the radio.
2:15
Professor Fred Watson: Really give me dick.
2:18
Andrew Dunkley: And when she, when she talked to me, she
2:20
said, don't change a thing. Which I
2:23
really. A great endorsement after being told
2:25
shut up for several years.
2:27
Professor Fred Watson: No. Well done. That's good.
2:30
Andrew Dunkley: Now, before we get started, how's the weather
2:32
down in Sydney? Because you've been copping
2:34
us spanking with the rain.
2:36
Professor Fred Watson: We did? Yes. one day last week, just
2:38
overnight, we had 97 millimetres or
2:42
getting on for five. Well four inches, isn't
2:45
it in the measure? Yeah, that's right, four
2:47
inches. that was just one night and all
2:49
together we probably had something like 150
2:51
of that wet period.
2:53
Andrew Dunkley: Yeah.
2:53
Professor Fred Watson: So it was very wet, very miserable, very
2:56
soggy. fortunately everything seemed to hold
2:59
up. Our downstairs granny flat which
3:02
used to flood when it rained but we had a lot
3:04
of work done last year. That's was in good
3:06
shape.
3:08
Everything seemed to be all right.
3:10
Andrew Dunkley: Yeah, I shouldn't tell you that right now
3:13
as we record there's a big
3:16
rain band headed your way.
3:18
Professor Fred Watson: Yes there is. That's right. We we already.
3:20
Andrew Dunkley: It's easing off now. We had rain all day but
3:23
I'm looking out now.
3:24
Professor Fred Watson: Yeah.
3:25
Andrew Dunkley: And it stopped raining. This the sky is
3:27
actually thinning. It's still quite grey but
3:29
it's moving that way which is more
3:32
due me.
3:34
Professor Fred Watson: It is. We're expecting that later this
3:36
afternoon. It sort of started off quite
3:38
bright this morning but it is definitely
3:40
looking a bit grayer now.
3:42
Andrew Dunkley: So yeah, I, I have some news.
3:45
At 2:37am M.
3:47
Saturday, oh, our
3:50
bedroom door rattled.
3:52
Professor Fred Watson: Okay.
3:54
Andrew Dunkley: And I, my first thought was that was an earth
3:57
tremor. And guess what it was.
4:00
It was a five point. Well they keep
4:02
varying it but at the time it was a 5.3
4:06
earthquake, centred around north of
4:09
Ningen which is Ningen's
4:11
160 kilometres west of us. And the
4:14
earthquake was north of them by about
4:16
98Ks. So it was a bit further
4:19
than 160 kilometres from us. And
4:22
yeah it shook because our door doesn't quite
4:25
latch perfectly, it doesn't hold tight so
4:27
it's always a bit loose. So when the air
4:29
conditioning comes on it usually goes thump.
4:31
They said did more than thump on Saturday
4:34
morning I went and I woke up,
4:37
went oh, earthquake. And Judy went, you sure?
4:39
Really? I said yeah, I reckon it was because
4:41
nothing else happened. Didn't feel any
4:43
vibration.
4:44
Professor Fred Watson: Okay, that's interesting. Yeah. You didn't
4:46
feel it, Just the door did.
4:48
Andrew Dunkley: well we got a great bed. Just very.
4:51
Professor Fred Watson: That's quite proof.
4:52
Andrew Dunkley: I had a lot for it. But yeah, it worked. We
4:54
didn't feel the earthquake but yeah, sure
4:56
enough next morning I thought I'd check and
4:58
Geosciences Australia confirmed it. So
5:01
5.3 which is 1 of the biggest ever recorded
5:04
out here.
5:06
Professor Fred Watson: Yes, that's right. Yeah it is. So one of my
5:09
colleagues at ah, the Australian Astronomical
5:11
Observatory or former Australian Astronomical
5:13
Observatory on the Anglo Australian
5:15
Telescope, he is One of the telescope,
5:17
operators, Andre Phillips,
5:20
he was sitting in the control
5:22
chair for the telescope and he felt something
5:25
as well. He felt the chair being sort of
5:28
moved, as though somebody was shaking it from
5:31
behind.
5:32
Andrew Dunkley: Yeah, that's what it feels like. Yeah.
5:33
Because I was in Newcastle earthquake and I'd
5:36
done an overnight shift when it hit and it
5:38
was 5.5. And
5:41
it felt to me like somebody just got the end
5:43
of the bed and was just bouncing, bouncing it
5:46
up and down and. Yeah, it was much more
5:48
violent than what we experienced.
5:49
Professor Fred Watson: It would be. Yeah. yeah, actually, Andre,
5:52
interestingly, this same gentleman I was just
5:54
talking about, he also runs, a very sensitive
5:57
seismograph at home because he's quite
5:59
interested in seismometry. so, yes, I think
6:02
he went home at the end of his night shift,
6:04
had a look, and sure enough there was a 5.3
6:06
or 5.2 earthquake, from
6:09
Lingen.
6:10
Andrew Dunkley: Yeah, he would have felt more of it in
6:12
Coonabarabran than he
6:15
calculation because, I looked at the clock
6:17
immediately and it was 2:37.
6:20
And I know that was the exact time because it
6:22
was an apple watch. So it was synchronised.
6:25
Professor Fred Watson: Yeah.
6:26
Andrew Dunkley: And I worked out that the vibration took
6:28
40 seconds to reach us.
6:31
Professor Fred Watson: Okay.
6:31
Andrew Dunkley: At approximately 300 kilometres an hour.
6:34
Professor Fred Watson: Yeah.
6:35
Andrew Dunkley: Just round.
6:37
Professor Fred Watson: Yes. Yeah, something like that.
6:39
Andrew Dunkley: Yeah. Anyway, give, Or take,
6:42
because I don't. It wasn't exactly 236, but
6:45
you know what I'm saying.
6:47
yeah. So exciting. Exciting. Haven't been any
6:50
aftershocks that I'm aware of. But, there's a
6:52
lot of tremors out here that you don't ever
6:54
feel or notice because they're just so small.
6:56
But, nothing that big.
6:59
We better get on with it, Fred Watson.
7:01
And our first story,
7:05
from the cosmos or closer to home, is a
7:07
possible new dwarf planet, in the
7:10
extremities of our solar system. This is,
7:13
really exciting, if it holds true and
7:16
it's sort of stacking up that way.
7:18
Professor Fred Watson: I think so, yes. this is
7:21
relatively straightforward,
7:24
astrometry, which is the measurement of
7:27
celestial objects in space, their actual,
7:31
direction. and it,
7:34
comes from, information
7:36
collected over quite a long period of time,
7:40
with, telescopes around the
7:43
world. so a lot of this discovery is due
7:46
to archival data where you can look at images
7:49
of particular bits of the sky and accurately
7:51
work out the position of objects in those
7:54
images. it's actually what you do, Andrew.
7:56
Just as an aside here, when a near Earth
7:59
asteroid is detected
8:02
the first thing astronomers do is look back
8:05
through archival, data. To see if there are
8:07
any, images, photographic images
8:10
or electronically detected images that will
8:12
show it. Because the longer you can observe
8:14
something for, the more accurately you can
8:17
deduce its orbit. And that is true with
8:19
this object, which turns out to be a
8:22
tno, a Trans Neptunian object.
8:25
it's been, studied by,
8:28
astrophysicists at the Institute for Advanced
8:30
Study in Princeton. Very, very
8:33
distinguished, institution.
8:35
and what they found, is an object
8:38
with the very unmemorable name of 2017
8:41
of 201. it
8:44
is an. An object. A trans Neptunian
8:47
object in a very, very elongated orbit.
8:51
its nearest point to
8:54
the solar system is. I think
8:57
it's 42,
9:00
thereabouts astronomical unit. Is that right?
9:03
No. 44,
9:05
44.5. That's its closest point to the
9:08
Sun. What we call the perihelion. 44.5
9:11
times that of the Earth's orbit. In other
9:13
words, 44.5 astronomical UN.
9:16
But the staggering thing is that it's
9:19
aphelion. the furthest point,
9:23
is, Now let me find
9:26
the number. It's much, much higher. You might
9:29
have 32.
9:32
I think it's more than that. where are
9:35
we? I think it's in the thousands. it's,
9:39
very, very distant. So
9:42
when it was found. I beg your
9:45
par. Yeah, when it was found, it was about 90
9:48
astronomical units away.
9:51
and there are enough observations that it's
9:54
sort of continuing its orbit.
9:57
1600. Yeah, 1600
9:59
astronomical units. That's its
10:02
furthest. And, that means that,
10:06
it's only going to be visible to Earth. based
10:09
telescopes for a few percent of its orbit.
10:12
When it's, when it's at its nearest,
10:14
point to Earth.
10:16
Andrew Dunkley: They're actually saying, Fred Watson, that
10:17
it's going far enough out to be
10:20
entering the Oort cloud.
10:22
Professor Fred Watson: That's right. Part of the inner Oort cloud,
10:24
which makes it a very interesting object
10:26
indeed with an orbital period,
10:28
if I remember rightly, of. What is it, 25,000
10:31
light years or something ridiculous like
10:33
that.
10:34
Andrew Dunkley: 25,000 years to complete an orbit.
10:37
Professor Fred Watson: Sorry, 25,000 years, not 25,000 light years.
10:39
Yeah. So it's a very, very distant object.
10:42
In fact, it's probably, Apart from
10:45
comets, it's probably one of the most distant
10:48
objects ever discovered.
10:51
because at its nearest, it's roughly the same
10:54
distance from the sun as Pluto is. But it's
10:56
furthest, as you've said. It's skimming the
10:59
inner edge of the Oort Cloud, that cloud of,
11:01
icy debris that we recognise as being the
11:04
source of comets, comets that drifting
11:06
towards the inner solar system. So a,
11:09
really, remarkable,
11:12
set of observations. It's been observed 19
11:15
times, so it's got a very high certainty
11:18
in its orbit. but the
11:20
quirky part of this, which you've already
11:22
alluded to, is that,
11:25
when the team, the research team who've
11:28
done this work, actually looked at the
11:31
simulations of, the way the
11:34
orbit of 2017, of
11:36
201, behaves,
11:39
they found that, its
11:42
orbit is only stable and long
11:45
term without Planet Nine.
11:48
so if you have Planet Nine in the
11:51
equation, then it gets thrown out within
11:54
100 million years, which means that's a short
11:56
time in astronomical terms. So,
11:59
yeah, it's it's that if.
12:01
Andrew Dunkley: Its existence is confirmed,
12:05
then Planet nine can't exist.
12:08
That's what they're saying.
12:09
Professor Fred Watson: That is what they are saying, yes. That it's.
12:11
This is, a quote from the media.
12:14
It's one of the strongest pieces of evidence
12:16
yet against the existence of Planet Nine.
12:21
yeah, that's right. it, it, it does
12:24
suggests that there are more objects of the
12:26
same kind. We haven't found them yet. but
12:29
yes, the figure I was looking for earlier, it
12:32
spends only 1% of its time in
12:34
orbit, near enough to be able to be
12:37
detected from Earth because
12:39
it's such a. It's a relatively small object
12:42
thought to be around 700 kilometres, which
12:44
probably makes it a dwarf planet rather than
12:46
a large asteroid. and,
12:49
the, that's imagining that something that
12:52
size can only be visible for
12:55
1% of its orbital period because the rest
12:57
just takes it too far away. It gives you a
13:00
good idea of just how elongated its orbit is.
13:03
Andrew Dunkley: Gee, we're lucky to have spotted it given the
13:05
timeframe.
13:06
Professor Fred Watson: Well, that's right, yes. because it'll drift
13:08
away and will very soon be, invisible
13:11
to our planet.
13:12
Andrew Dunkley: And it's a lot of weight to a theory we
13:15
talked about some time ago from one
13:18
scientist who said there is no Planet Nine.
13:21
I think there's a whole bunch of stuff out
13:23
there that's causing the same effect.
13:26
And this sounds like one of those things.
13:29
Professor Fred Watson: Yes, that's right. And it's similar. There
13:32
was a similar argument around the same time
13:34
by another group of scientists, one of whom I
13:36
actually spoke to in Canada a couple of years
13:39
ago, who said effectively that
13:42
the evidence for Planet Nine is based on.
13:45
I don't know it's probably a dozen or so
13:48
of these icy asteroids all of whose
13:50
elongated orbits sort of line up in the same
13:53
way. And the suggestion that was being
13:56
made by these other scientists is that
13:58
actually it's not so much
14:01
that it's a selection effect. We just haven't
14:03
found all the other ones that aren't aligned
14:05
in the same way. that would
14:08
contradict the idea of Planet nine. So
14:11
yes, this object might be the poster child of
14:14
the anti Planet nine lobby. but it
14:17
does seem to suggest that it does not
14:20
Planet nine does not exist. And just to
14:24
underline what we're saying earlier, it has
14:26
actually been officially confirmed
14:29
as an asteroid by the International
14:31
Astronomical Union. So it will no doubt
14:34
get a name because once it's confirmed by the
14:37
IAU then you can give it a name.
14:40
Andrew Dunkley: Asteroid or dwarf planet.
14:44
Professor Fred Watson: I mean a, ah, name like you know, Pluto
14:46
or Makemake or one of
14:49
those names.
14:50
Andrew Dunkley: But we're calling it a dwarf planet.
14:52
Professor Fred Watson: That's, that's right, that's right, yeah. At
14:54
700 kilometres. I don't think the IAU
14:57
makes a distinction when they, when they
14:59
actually confirm its orbit. They don't
15:02
say anything about its size
15:05
because that's dependent on, but that, that
15:07
depends on measurements that are a lot more
15:09
difficult to do. But once its orbit's been
15:11
confirmed then it becomes an official object
15:14
which could be either a dwarf planet or an
15:16
asteroid.
15:16
Andrew Dunkley: Okay, all right, so the jury might still be
15:19
out for a bit but yes, it's there and
15:22
it looks like that's put the kibosh on
15:25
Planet Nine. More to come on
15:28
that one I'm sure. Yes. Now
15:31
if you'd like to read all about it you can do
15:33
that@sciencealert.com
15:35
this is space Nuts, Andrew Dunkley here with
15:38
Professor Fred Watson Watson.
15:41
Now let's take a quick break from the show to
15:44
tell you about our sponsor
15:45
Insta360 and their brand
15:48
spanking new top of the line camera, the
15:50
Insta360X5.
15:53
This is as Fred Watson would say, a beautiful
15:56
piece of kit. It's the ultimate
15:58
360 degree action camera
16:02
and it's designed for everybody, creators,
16:05
adventurers, professionals, but even
16:07
amateurs who just want a better job. this is
16:10
the camera for you and you can capture
16:13
the world in 8K resolution.
16:16
It's got dual sensors, it's
16:19
got 72 megapixel photos for ultra
16:22
clear pictures in true to life colour.
16:25
And it's Got a very powerful AA
16:28
chip system, which will give you exceptional
16:31
image quality even in low light conditions.
16:33
It's got everything. It's also got a pure
16:36
video mode so you can just capture everything
16:39
you want. And what I love about this camera
16:42
is you don't have to point it at something to
16:43
get your footage. It will just film
16:46
360 degrees and then you figure out what you
16:49
want later. It's so seamless, so easy, so
16:51
simple, you know, I don't think you'd be
16:53
disappointed at all. And whether or not you,
16:56
you know, out on holidays or, or
16:59
filming something for a professional finish,
17:02
you won't have a problem with the X5.
17:05
It's got, incredible durability. it
17:08
can operate in just about any circumstances,
17:11
including underwater. If you break a lens,
17:13
you can replace it. Just pop one out, pop one
17:15
in. Really quite simple. Up to
17:18
185 minutes of battery life. so much
17:21
going for this beautiful
17:22
insta360x5 camera.
17:25
And at the moment, as a Space Nuts listener,
17:28
there's a special deal for you. You, if you
17:31
sign up for an Insta360 standard
17:33
package and one of the first 30 to do so,
17:37
you will also get a little bit of a
17:39
present, an invisible selfie stick.
17:42
So, all you have to do is go to this
17:45
URL to find out more and sign
17:48
up for the, the standard package, the
17:51
Insta360x5.
17:54
And you do that at store.
17:59
That's
17:59
store.insta360.com
18:03
and don't forget the promo code, Space Nuts.
18:06
with this special deal going right now on the
18:09
standard package for the
18:10
Insta360x5 camera, that's
18:13
store.insta360.com
18:16
and use the promo code Space Nuts. We've got
18:19
all the details in our show notes.
18:23
Now back to Space Nuts.
18:27
Space Nuts. Let's move on to our, next story.
18:30
Fred Watson, I find this one fascinating for
18:32
one reason. This is going to sound
18:35
strange. I've never heard of this place.
18:37
Professor Fred Watson: Oh really? I think I heard of it.
18:39
Andrew Dunkley: it's a moon of Saturn known as
18:42
Iapetus now. And I say I've never
18:45
heard of it. When I saw the picture I went,
18:46
oh, yeah, I know I've seen that picture
18:48
before. Yes, because it's
18:51
unique. That's why, this moon is
18:54
so very interesting. Because
18:57
questions are still being asked as to how it
18:59
looks the way it does. It's a strange place
19:02
and it's getting, a fair bit of attention
19:05
in social media at the moment,
19:08
amongst other things. But, yes, it's back in
19:10
the news.
19:11
Professor Fred Watson: It is back in the news. I think it is really,
19:13
as you say, I think it really is social media
19:15
that stirred this up. we. So,
19:18
you know, until 2017, when the
19:21
spacecraft plunged into the atmosphere of
19:24
Saturn, we were absolutely,
19:28
swamped by marvellous photographs of
19:30
the moons of Saturn from the Cassini
19:33
spacecraft. told us more about the moons of
19:35
Saturn than we could ever have guessed that
19:37
we'd learn. and I think,
19:40
So Iapetus was certainly very much in the
19:43
headlines then because it is such a peculiar
19:46
world. but it sort of. Because
19:49
so many of the questions don't really have
19:50
proper answers, that's
19:53
allowed it to sort of fade from, from
19:56
the attention of planetary scientists. But
19:59
it's been spotted by, I mean
20:02
spotted in the media by social, Social
20:05
media people who have really raised it
20:08
once again, you know, as a place of
20:11
great interest. And maybe that will encourage
20:13
some of the planetary, scientists who've
20:16
certainly had an interest in Iapetus, to go
20:18
back to some of the Cassini data, maybe
20:21
using, you know, more modern AI
20:23
methods to analyse it and actually check out
20:26
what is going on there.
20:29
so it's the first thing you'd find
20:32
out about Yapetus. And it
20:35
was when it was discovered back in
20:38
the 17th century, Giovanni
20:40
Cassini, that great, observer who
20:43
discovered the Cassini Division since the
20:45
name, made
20:48
the discovery that this, this little
20:51
world orbiting Saturn, is
20:54
peculiar because one side of it was very
20:57
much darker than the other. I remember
20:59
actually at the start of my career, back in
21:02
the, early 1970s when I was working at
21:05
the Nautical Almanack Office of the Royal
21:07
Greenwich Observatory with one of my
21:09
colleagues there, Andy Sinclair was a
21:11
specialist on Iapetus and he kept telling me
21:13
it was a very peculiar world. but it was only
21:16
when Cassini flew by a few decades later that
21:19
we realised just how peculiar it is. So
21:22
it is covered in craters,
21:25
but it's got this dark side which
21:27
just looks as though it's been spattered with
21:30
soot. Looks as though, you know, somebody's
21:33
put a pile of soot out there and Iapetus,
21:36
has run into it. and you've. So
21:39
you've got this very dark face to it,
21:41
contrasting with a very highly reflective
21:43
surface. now
21:46
that's peculiar in itself because
21:49
it's only on one side and that's the forward
21:51
facing side. Iapetus goes around Saturn
21:55
tidally locked, so that it always keeps the
21:57
same face to Saturn. That means there's
21:59
always a forward side and a backward side.
22:02
This stuff's on the forward side. If I'm
22:04
actually remembering from my, talks on
22:07
Cassini, ah, back in the day, I haven't done
22:09
one of those for nearly a decade. But anyway,
22:12
that's the one peculiar thing about it, but
22:15
the other one is even weirder. And this is
22:18
this equatorial ridge, a ridge that goes
22:21
all the way around it. It's something like 10
22:23
kilometres, or thereabouts.
22:26
It's a line of mountains, effectively, but
22:29
it's right along the equator
22:33
of Iapetus.
22:34
Andrew Dunkley: It reminds me of a walnut.
22:37
Professor Fred Watson: It is. That's right. I used to think it
22:39
looked like a walnut. Exactly that. and
22:42
so, I mean, there's various
22:44
theories as to how it got there. And the one
22:46
that I thought was the most common
22:49
one, was that,
22:53
it was caused by the contraction of the crust
22:55
of Iapetus.
22:57
Andrew Dunkley: That makes sense.
22:58
Professor Fred Watson: the, you know,
23:00
Iapetus cooled after its creation.
23:03
it's rotating on its axis. the
23:06
crust contracts until you get a
23:09
bulge which naturally forms around the
23:11
equator of rotation, right angles to the axis
23:14
of rotation. But, I think other
23:17
hypotheses have, have
23:20
been put forward. One is
23:23
that perhaps there was a ring system
23:26
around Iapetus that actually
23:28
collapsed and fell onto the surface and
23:31
generated the ring of mountains.
23:34
another one is possibly icy material
23:37
coming out from beneath the surface of
23:39
Iapetus. We know that, many of the
23:42
moons of the, of those outer planets,
23:45
got ice or perhaps icy
23:48
slush underneath the surface.
23:52
because of, the fact that they're what we
23:54
call ice worlds with a, with a central rocky
23:57
core, a, liquid ocean above it, which
24:00
may be quite slushy. and then a crust of
24:02
solid ice on top of that. That could be the
24:05
construction. Once again, if you've got stuff
24:07
coming up from beneath the surface and the
24:09
object is spinning fast enough, then you
24:12
will get, perhaps a ring of
24:14
mountains like we see on the apertus,
24:18
none of which come from the original idea,
24:21
which was contraction. So I'm very
24:23
interested to know where the scientific,
24:26
you know, the scientific, consensus
24:29
is going on this little world. And, it's
24:31
great that it's, it's cropped up again, it's
24:33
welled up again into the public
24:34
consciousness.
24:35
Andrew Dunkley: It has, yeah. Another theory I read was just
24:38
a high spin rate at some stage.
24:40
Professor Fred Watson: Yes.
24:41
Andrew Dunkley: Yeah, that would Cause a bulge rather
24:44
than a mountain range. I would, I would
24:45
expect that.
24:47
Professor Fred Watson: Well you'd normally that causes a
24:50
planet to flatten slightly so that it's
24:53
it's. Yes it's a bulge. It's the ah, Earth's
24:56
shape is that ah, what we call an oblate
24:58
spheroid. Saturn itself actually is the
25:01
most extreme example in the solar system
25:03
because it's the diameter
25:06
between the poles is significantly less than
25:09
the diameter across the equator. and it's
25:11
this kind of oval shape in cross section.
25:14
so that's what you'd expect from something
25:17
rotating quickly not as a
25:20
well defined ridge of mountains like
25:23
we see on Iapetus.
25:25
Quite an amazing world.
25:27
Andrew Dunkley: Another weird factor I suppose is its
25:30
proximity to Saturn. It's actually a long way
25:32
away.
25:33
Professor Fred Watson: Very far. Yes, that's right. So what is it?
25:35
3.2 million millimetres or
25:38
thereabouts? It's a long, long way,
25:41
3.22 million kilometres from Saturn.
25:45
Andrew Dunkley: Could the dark face be some sort of reaction
25:48
with Saturn radiation or something like that?
25:51
Professor Fred Watson: It's the thinking back in the
25:53
Cassini era and I suspect it's probably
25:56
similar is that it consists of organic
25:59
chemicals that form this kind of
26:02
soot. I think solens might have
26:04
been in invoked as well. These are
26:07
particular organic chemicals that we
26:10
know coat a lot of the outer worlds because
26:13
they're generated by I think the impact of
26:15
cosmic rays on material.
26:18
but it's the peculiar thing is that
26:21
it's ah, only on one side. It looks as though
26:23
it's just kind of run into something that's
26:25
splattered all over the front of it.
26:27
Andrew Dunkley: It's got that impression. Yeah. Somebody
26:29
spilled the paint.
26:31
Professor Fred Watson: Just what it looks like. That's why.
26:32
Andrew Dunkley: Really odd. Yeah. If you'd like to take a
26:34
look at it. Yapetis is all over the Internet,
26:37
lots of social media. But there's a great
26:39
article@dailygalaxy.com worth
26:42
reading on Yapetis. It starts with an I. It's
26:45
spelled I A P E T U S
26:48
Yapetus. This is Space Nuts with Andrew
26:51
Dunkley and Fred Watson Watson.
26:55
Roger, you're last Nuts.
26:58
Our final story today Fred Watson ah,
27:01
takes us to the very rare
27:04
area of black hole discussion.
27:07
we get so many questions on this. I mean
27:10
it's, it's unbelievable. In fact I think
27:13
there was a question popping up about black
27:15
holes in our next episode as
27:18
a matter of fact. But and, and I think the
27:21
reason is quite simple. People just want to
27:23
understand Them and there's so much we don't
27:26
know.
27:29
this particular story focuses on
27:31
primordial black holes and the possibility
27:34
that they may well be responsible for today's
27:37
dark matter. Please
27:40
explain.
27:42
Professor Fred Watson: Well, yeah, this is a piece of theoretical
27:45
research which is good
27:48
because you need it. it's ah,
27:51
this is research by Japanese scientists
27:54
in Tokyo and elsewhere.
27:57
and what you have got
28:00
here is people who are ah, looking
28:04
sort of almost with new eyes if I can put it
28:06
that way, at the dark matter problem because
28:10
dark matter is a big problem. We've got this
28:12
stuff that seems to have a gravitational hold
28:15
on galaxies so that they don't fly ap.
28:18
and a ah, gravitational hold on galaxy
28:21
clusters so they don't fly apart as well. and
28:23
yet we can't detect it. We cannot detect it
28:26
in any way other than by its gravitational
28:29
pull.
28:30
Andrew Dunkley: Yeah, we've never captured any of it or
28:32
anything like that.
28:33
Professor Fred Watson: No, that's right. So this, the, the you know,
28:36
what, what, what have we got to go on?
28:40
Not very much, ah, in terms of
28:43
our understanding. however
28:47
there was quite early on in the black, in
28:50
the dark matter story, a number
28:53
of experiments carried out on on
28:56
big telescopes. One of which was actually
28:58
here in Australia a very historic
29:01
telescope called the 50 inch at Matt
29:03
Strongloe, previously known as the Great
29:06
Melbourne Telescope because it's very old but
29:08
it had been modernised with new equipment.
29:11
And they did an experiment which was called
29:13
macho. And it was
29:16
designed to look for the gravitational
29:19
lensing effect of large objects
29:22
in the, in the
29:25
universe, basically in the vicinity of our
29:27
galaxy. And by large objects I mean things
29:29
that aren't subatomic particles. So I
29:32
mean things like orphaned planets,
29:35
dead stars or black holes.
29:38
MACHO was actually an acronym for Massive
29:40
Compact Halo Objects. Now they
29:43
didn't see as
29:46
many of these gravitational lensing
29:49
phenomena,
29:52
in other words the space around one of these
29:54
objects being bent so it magnifies an object
29:56
behind it. They didn't see any in
29:59
numbers that were sufficient to make
30:01
machos the missing
30:04
dark matter. And so that was in
30:07
the 90s that really ruled
30:10
out things like black holes as being
30:13
the culprits for dark matter.
30:15
And so that's when we were you know, our
30:18
attention was shifted to the idea that dark
30:20
matter is actually some species of subatomic
30:23
particles, perhaps many species, but ones
30:25
that don't interact in any way with normal
30:27
matter. And that's where things remain today.
30:30
So it's interesting to find a paper which
30:33
kind of goes back to an older idea that
30:36
maybe black holes actually do
30:38
contribute to the dark matter. and the
30:41
reason why I think this paper has been
30:43
published. Is that there is a slightly new
30:45
twist to it. Because these are,
30:49
The postulate is that these are primordial
30:52
black holes. Black holes which were created
30:54
at the same time as the universe was. In
30:57
other words, during or immediately after the
30:59
Big Bang. so that
31:02
you, you basically,
31:05
find these objects potentially. We,
31:08
we've never observed a primordial black hole.
31:11
People just kind of guess that they are
31:12
there. And we do see black
31:15
holes that, that, that
31:18
maybe fall within the mass range of a
31:20
primordial black hole. But, we don't
31:23
actually know that they exist. But,
31:27
to come to the point, I'm not being very
31:28
clear here. What has actually
31:31
led, to this research is that the
31:34
lifetime of a black hole is
31:36
possibly much, much longer than
31:39
Hawking predicted that these primordial black
31:42
holes would last. He gave them because they
31:45
were smaller. He gave them a relatively short
31:47
lifetime. Black holes, we know, do
31:49
evaporate because they release Hawking
31:51
radiation. This quantum, mechanics phenomena.
31:55
and, the
31:57
idea, even though that is a very, very slow
32:00
process. If you've got these sort of mini
32:02
black holes that were formed in the,
32:05
origin of the universe, our thinking was that
32:07
they might all have evaporated by now. And
32:10
that's where this new research comes in.
32:12
Because they're proposing a new mechanism,
32:15
which has got an interesting name. It is,
32:19
something called. I've lost
32:22
the name of it. M It's basically,
32:24
yes, the memory burden effect. Work that one
32:27
out. Yeah, the memory
32:29
burden effect, suggests that,
32:34
the information stored, if I can put it that
32:37
way, in the black hole. Actually stabilises
32:39
it and keeps it, from decaying. So
32:42
that the. To cut to the quick, the
32:45
idea is that these primordial black holes.
32:48
Might last a lot longer than Hawking
32:50
predicted they would. And perhaps they are,
32:53
after all, the missing dark matter.
32:56
Now, that still has to account for why we
32:58
didn't detect them by gravitational lensing.
33:01
During the Macho experiment. And similar
33:03
experiments carried out elsewhere in the
33:05
world. But it is an interesting possibility.
33:08
Andrew Dunkley: Yes, yes.
33:11
it's probably the best theory we've got, I
33:13
suppose, at the moment.
33:15
Professor Fred Watson: yeah. I'm not sure that it is. Oh,
33:18
okay. I, think, You
33:21
know, I, I Because
33:24
we don't even know whether primordial black
33:26
holes actually exist. we don't know that
33:29
these subatomic particles exist either. but
33:32
it seems to me that the bill is better
33:35
fitted by what black holes might be.
33:38
sorry, by what dark matter might be. by
33:41
the subatomic particles rather than
33:44
primordial black holes.
33:46
Andrew Dunkley: Well, they won't be letting you do a peer
33:48
review, will they?
33:49
Professor Fred Watson: They won't. No, that's about me. I've made my
33:51
mind up already, you see, but we don't know
33:53
what they are. What? You know, are they
33:55
neutralinos? Are they WIMPs?
33:57
Weakly interacting massive particles?
34:00
Sterile neutrinos? There's all kinds of
34:02
things that have been proposed for these,
34:04
subatomic particles, but none have yet been
34:07
detected.
34:07
Andrew Dunkley: Yeah, all right, interesting. I'm sure
34:10
that'll spawn no questions whatsoever from
34:12
our audience.
34:14
Professor Fred Watson: Heidi will have to deal with them next time.
34:16
Yes, he will.
34:17
Andrew Dunkley: Yes, she will indeed.
34:20
so if you'd like to chase that up, there's a
34:22
great article, on fizz
34:26
detecting the primordial black holes that
34:28
could be today's dark matter. Fred Watson
34:30
thinks not. But, that's what science
34:33
is about, tossing these ideas around. And
34:36
that brings us to the end of yet another
34:38
episode of Space Nuts. Thanks, Fred Watson.
34:41
Professor Fred Watson: It's a pleasure, Andrew. Always good to talk.
34:43
And, I look forward to our next time.
34:45
Andrew Dunkley: Indeed. And thanks, to Huw in the
34:48
studio who couldn't be with us today. He
34:50
found himself a primordial black hole and.
34:52
And we've not seen him since him since
34:56
Baron Feed Love Spaghetti. with me,
34:59
Andrew Dunkley. Thanks for your company.
35:01
Catch you on the next episode of Space Nuts.
35:03
Bye. Bye.
35:05
Voice Over Guy: You've been listening to the Space Nuts
35:07
Podcast, available at
35:10
Apple Podcasts, Spotify,
35:12
iHeartRadio or your favourite podcast
35:15
player. You can also stream on demand at
35:17
bitesz .com. This has been another quality
35:20
podcast production from bitesz .com.