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Primordial Black Holes, Planetary Chemistry & Lunar Crater Discoveries · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Andrew Dunkley: Hello once again, thanks for joining us. This
0:03
is Space Nuts. My name is Andrew Dunkley.
0:05
It's great to have your company. We talk
0:07
astronomy and space science on this show and
0:09
we hope you enjoy it. Uh, all five listeners
0:12
have actually said at some stage or another
0:14
in the last decade that they did enjoy one or
0:16
two episodes out of the 618 we've done. So
0:20
that's a pretty good record. Uh, but we'll
0:22
press on. We'll press on. Uh, what we've got
0:25
coming up for you today is extraordinary.
0:27
We're going to talk about, uh, black holes.
0:29
Uh, these ones though, uh, are only thought
0:32
to exist. But they're starting to piece
0:35
together evidence that they are. And
0:38
we're talking about primordial black holes.
0:40
But what's really interesting is
0:42
how they all began. Maybe we'll
0:45
get into that. Uh, and uh, planets
0:48
and their chemical makeup compared to their
0:50
parent star. There's been a major discovery
0:52
there. And a fresh moon crater, a
0:55
big one. You could put a couple
0:58
hundred thousand people in this one, uh, to
1:01
watch a football game. Uh, that's all coming
1:03
up on this episode of space nuts.
1:06
Generic: 15 seconds. Guidance is internal.
1:09
10, 9. Ignition
1:11
sequence start.
1:13
Professor Fred Watson: Space nuts.
1:13
Generic: 5, 4, 3, 2. 1, 2, 3, 4,
1:16
5, 5, 4, 3, 2, 1.
1:18
Andrew Dunkley: Space nuts.
1:20
Generic: Astronauts report it feels good.
1:23
Andrew Dunkley: And back once again to fill in the blanks is
1:26
Professor Fred Watson Watson, astronomer at
1:28
large. Hello, Fred Watson.
1:29
Professor Fred Watson: Hi, Andrew. Um, I do apologise for
1:32
my pre broadcast sneeze there that I hope you
1:35
didn't pick up on the headphones.
1:37
Andrew Dunkley: I'll have to listen back, but that's okay. I
1:39
mean, we've got everything that happens on
1:41
this show.
1:42
Professor Fred Watson: Yeah,
1:44
Andrew Dunkley: I used to actually welcome that stuff on my
1:47
radio show because, um, I just thought it
1:50
made everything more human. If you had
1:52
somebody sneezing or tripping over or banging
1:54
a wall or walking in on you.
1:57
That was always fun. Um,
2:00
ye. I. My philosophy was
2:03
if you walk in, you're in the show. End of
2:06
storey. Um, nobody really
2:08
escaped. Uh, how are things Fred Watson, by
2:11
the way?
2:12
Professor Fred Watson: Uh, fine, I think. Yes. I don't know why I
2:14
sneezed. I think I um, might have caught the
2:16
lurgy that you.
2:17
Andrew Dunkley: Oh yeah, I've got a bit of something. We took
2:19
the grandchildren out and took them, took
2:21
them to a place called Inflatable World.
2:25
Okay. You jump in castles and slides and,
2:28
you know, air guns and things. Not the ones
2:30
that fire lead pellets, but, uh, they fire,
2:32
you know, plastic balls. Uh, they had a great
2:35
time but um, I fear because there were
2:38
10 million kids there, um, and half of
2:41
them had lots of stuff coming out their nose.
2:43
I might caught something.
2:47
Might have caught something there.
2:50
Professor Fred Watson: I can't say I've noticed anything coming out
2:52
of your nose. So you.
2:53
Andrew Dunkley: Well, just hang around. Just hang around.
2:58
I'm all dosed up. It dries you out, that
3:00
stuff. It's good. That's why they've made it
3:02
illegal.
3:05
Well, no, it's behind the counter now, I
3:08
think is the rule. You can't get it off the
3:10
shelf. You've got to ask the pharmacist for
3:12
the. For the good state. But it is good
3:15
stuff. Good stuff. All right, let's carry on.
3:18
My voice is already starting to fail me. Uh,
3:21
Fred Watson, let's.
3:21
Let's begin because this is a really exciting
3:24
storey. Uh, we have talked many times about
3:27
black holes, about, um,
3:29
dark matter, um, and we've talked
3:32
about primordial black holes. And now they're
3:35
starting to think maybe there's a
3:37
relationship there. We've got to prove one
3:39
that might prove the other, which might solve
3:42
the problem of dark matter. Am I right about
3:45
that? That theory?
3:46
Professor Fred Watson: Yes, you're right. You are right, yes. In
3:48
fact, you've told the storey in a much more
3:50
succinct way than I'm going to now.
3:52
Andrew Dunkley: Okay, well, that's going to make things fast.
3:56
Professor Fred Watson: So, um. So this is a storey from
3:59
ligo, the Large Interferometric
4:02
Gravitational Wave Observatory, which has
4:04
two, uh, um, locations, two
4:07
detectors, one in Washington, one in
4:09
Louisiana. Uh, and
4:12
the, I mean, the first of those,
4:15
um, detections was quite a number of years
4:18
ago now. Uh, so we've known about these
4:21
gravitational waves. I think it was. Might
4:23
even have been 2015. Um,
4:26
I, um, might be confusing. I do remember it
4:28
was, uh. The detection was on Marnie's
4:30
birthday, the 14th of September. So. Cool. I
4:33
can't remember what year it was. Anyway,
4:36
whatever it was, uh, it was a good year
4:38
because for the first time we could sense the
4:41
collisions of, um, objects
4:44
colliding in space. Sorry, there's
4:47
tautology there. We could sense the
4:49
gravitational wave signal of objects
4:51
colliding in space. Yes, we're both in
4:54
good form today.
4:55
Andrew Dunkley: I think we are. 2015.
4:57
14-9-2015. Spot on.
5:00
Professor Fred Watson: Thanks. So that
5:04
was, um, the first time. And, um, the
5:07
track record of LIGO is incredible. You know,
5:09
we celebrated the first detection and the
5:11
second and the third, and then it got a bit
5:14
routine and now they just churn them out.
5:16
Um, but we've had black hole. Black hole
5:18
collisions. We've had neutron star black hole
5:21
Collisions. And we've had neutron star,
5:23
neutron star collisions. And each
5:26
of them gives a different sort of
5:28
gravitational wave signature. And that's the
5:31
critical thing, uh, that you can tell
5:34
just by looking at the. It's almost like an
5:37
acoustic wave, but it's on a
5:39
microscopic scale because the vibrations
5:42
are, uh, infinitesimally small,
5:45
as we've discussed before. That's because
5:48
space is so rigid. But these gravitational
5:50
waves, as they pass through the Earth, they
5:53
change the separation of two mirrors
5:56
in what's called an interferometer.
5:58
That's how LIGO works, with tiny, tiny
6:01
differences. Uh, so, uh, those waves
6:05
have a, uh. Because they come in, actually
6:07
it's quite interesting. They come in at more
6:09
or less acoustic, uh, frequency ranges. So
6:12
if you amplify them up, you can hear it.
6:16
Uh, it's a little bit more complicated than
6:18
that, but you can actually, you know, it's
6:20
within that wave band that we can hear
6:22
things, even though it's sound that we, uh.
6:24
And it's the vibration of space itself that,
6:27
um, LIGO hears or sees.
6:30
Um, so, uh, what
6:33
has now happened is that,
6:36
uh, uh, a group of. I think the
6:39
group is based at the University of Miami,
6:41
the researchers who've done this work,
6:44
um, but they found a signature
6:47
of a collision that involved,
6:50
um, a star, or
6:53
let me put it this way, an object which
6:56
is a smaller mass than the
6:59
Sun. Uh, now
7:02
a black hole that small
7:06
should not exist in conventional
7:09
wisdom because the way we believe black holes
7:11
are formed is by stars
7:14
collapsing, uh, at the end of their
7:17
lives, uh, as they
7:20
detonate with a supernova explosion. The core
7:22
collapses. The, the outer layers get
7:25
shed into space, but the core collapses. Uh,
7:27
and you've got a black hole, uh, an object
7:30
with very, um, intense gravity
7:33
because it basically collapses to a
7:34
singularity, a point in space.
7:36
Generic: Yeah.
7:37
Professor Fred Watson: Uh, but, um, the conventional wisdom
7:39
is that you need stars whose mass,
7:43
whose initial mass is, you know, 5,
7:46
6, 7, 8, 9, 10, perhaps times the mass of the
7:49
Sun. That sort of level, usually
7:52
10ish times the mass of the sun, is typically
7:54
what you get. And so the black
7:57
hole remnant that you get has a very similar
8:00
mass to that. The outer envelope has been
8:03
blown off. But most of the star's
8:05
mass basically concentrates into the black
8:08
hole. So finding a signature
8:11
of an object that has
8:14
less mass than the sun is
8:17
inexplicable, uh, in
8:20
conventional astrophysics. Um, it's
8:23
too small. Uh, so,
8:26
uh, what are the possibilities? And the thing
8:28
that your mind, I'm sure, went straight
8:31
towards, as did mine, is
8:34
primordial black holes. And these are, uh,
8:36
objects that were predicted by Stephen
8:39
Hawking, um, back in the
8:41
1970s. He proposed the existence
8:44
of objects that
8:47
basically turned into black holes
8:50
in the aftermath of the Big Bang,
8:53
where you've got pockets of
8:55
subatomic material that could
8:58
essentially collapse directly into a
9:01
black hole without needing a, ah, star
9:04
to go through, you know, to be formed and go
9:07
through its, um, its lifetime and then
9:09
collapse at the end of that, um, but all
9:11
within, you know, the first, well,
9:14
probably less than a second of the
9:17
universe's existence. Uh, Hawking's theory
9:20
suggests that these, uh, black holes
9:23
were formed. Uh. Now
9:26
nobody's proved anything yet. They've
9:29
basically been
9:31
theoretical entities. Uh, and,
9:34
um, there's been no evidence to suggest
9:37
that any of them exist.
9:40
Until now. Yes, uh,
9:43
where you have, um, a
9:46
primordial. Perhaps a primordial black
9:49
hole being detected with its
9:52
collision, uh, that
9:54
essentially can, uh, only be replicated
9:58
if one of the objects has less than the mass
10:00
of the sun. Uh, so where
10:03
does that take us? It takes us
10:05
straight back to dark matter.
10:08
Because one of the things that was
10:11
ruled out in the early days of
10:14
our understanding of dark matter, this is
10:16
back in the 19, uh, 70s, late
10:19
1970s and 1980s, was, uh, black
10:22
holes. Um, we ruled out black holes because
10:25
we thought that they would all have masses
10:28
much greater than the mass of the sun and
10:31
that would reveal itself because if you
10:34
did a survey of, uh, like,
10:36
um, a survey that was done with
10:39
the, um, what, what used to be called the
10:42
50 inch telescope at Matt Stromlo Observatory
10:45
here in Australia, this was in the 1980s.
10:48
Um, that telescope, which is a storey in its
10:51
own right, that we haven't time to go into
10:53
now. Uh, but that telescope was used for a
10:56
survey which was called macho. And that's
10:59
because I remember that, yeah, MACHO
11:02
is massive compact halo objects. And what it
11:05
was looking for was evidence that the dark
11:08
matter might be something solid rather than
11:10
subatomic particles, which is actually the
11:13
prevalent theory now. And by solid they
11:16
meant, um, dwarf planets,
11:19
rogue planets, uh, um, black
11:22
holes, things that exist as
11:24
a compact object that would distort
11:27
the space around them. So that you'd get
11:30
this, what's called gravitational
11:31
microlensing effect. You'd get a
11:33
magnification as this thing passed in front
11:35
of a distant star. You get a magnification of
11:37
the light from that star, which would be
11:39
detectable by the MACHO experiment and the
11:42
50 inch telescope, as it was called.
11:45
Um, and while one or two
11:48
of these gravitational microlensing events
11:50
was found. It was nowhere near enough
11:53
to be able to use black holes as
11:56
the basis for dark matter, which is why
11:58
interest was lost in the idea that this is
12:01
solid particles and the whole idea of
12:04
it being WIMPs, the opposite of machos,
12:06
WIMPs, weakly interactive massive particles.
12:09
That's where that all emerged and that's
12:11
where we are now. Um, most of the
12:14
world of physics believes that there are some
12:16
atomic particles that account for
12:20
the dark matter, which of course reveals
12:22
itself by its gravitational influence either
12:24
on the rotation of galaxies or the,
12:27
um, the movement of galaxies in clusters or
12:30
indeed the structure of the universe at
12:32
large. It seems to suggest it's there. So
12:34
the finding of a primordial, of
12:37
a less than 1 solar mass black
12:40
hole, which would have to be probably a
12:43
primordial black hole, uh, opens up that
12:46
possibility again. Because if you can find
12:49
one, there might be gazillions of
12:52
them out there.
12:53
And, uh, we might be, you know,
12:56
misinterpreting what we're looking for. If
12:59
we're not looking for small, uh, black holes,
13:01
we're actually looking for subatomic
13:03
particles that maybe don't exist. We have at
13:05
least one listener to space nuts, uh,
13:08
whose name is Pete, uh,
13:11
who doesn't think they exist because he's
13:13
researching one of the alternative
13:16
theories, the MOND theory, modified Newtonian
13:19
dynamics.
13:21
Andrew Dunkley: Yeah, it's really interesting, but, um,
13:23
it's still kind of a theory, isn't
13:26
it? I know they've made this detection using
13:28
ligo, but they have to confirm it
13:31
by making another detection, don't they?
13:35
Professor Fred Watson: Uh, yes, you'd want to see more
13:38
and you'd kind of want to start seeing
13:40
evidence of other kinds. For example, if
13:43
you revisited the MACHO experiment and look
13:46
for the gravitation, the um,
13:48
gravitational macro ending signal of
13:52
tiny black holes that were created in the Big
13:54
Bang, then, uh, that might confirm
13:57
this and give the, um,
14:01
idea of primordial black holes
14:04
being the dark matter. It would give it a
14:06
much more solid observational basis.
14:09
Andrew Dunkley: Yeah, well, it stands to reason that, uh,
14:12
if Stephen Hawking says so, it's probably
14:14
true. Um, but,
14:17
uh, it wasn't so long ago that you and I were
14:20
talking about black holes and we were saying,
14:23
look, there's super massive ones and there's
14:25
small ones, but there's no in between ones.
14:27
And I think within a week or two of us having
14:29
that conversation, they found one and now
14:31
they've found a bunch. So
14:34
now we're going even smaller and
14:37
it could reveal a heck of a lot, um, maybe
14:40
solve some of those Mysteries that we've been
14:42
talking about forever and getting bombarded
14:45
with in terms of questions.
14:47
Professor Fred Watson: Yes, which is just as well because. Oh
14:50
yeah, keeps us, keeps us going.
14:51
Andrew Dunkley: It does indeed. Ah, fabulous storey. If
14:54
you'd like to read about it, it's at uh,
14:57
space daily.com. uh,
14:59
and um, yeah it's a really fascinating
15:02
article about a uh, sub solar black hole.
15:06
Just uh, change the dark matter debate is the
15:09
title of the article. Uh, it is
15:12
isn't it? It's a really great read.
15:14
This is Space Nuts with Andrew Dunkley and
15:16
Professor Fred Watson Watson.
15:20
Generic: Roger, you're lots three here.
15:22
Professor Fred Watson: Also Space Nuts.
15:23
Andrew Dunkley: Our uh, next storey Fred Watson is just as
15:26
fascinating because they have done uh, a bit
15:29
of an analysis of chemical analysis on
15:31
a planet, an ultra hot Jupiter
15:35
and they have made some extraordinary
15:37
discoveries.
15:39
Professor Fred Watson: Yeah, they're, these are um, they're
15:42
great discoveries because
15:45
the technology and the techniques required
15:48
to make these are uh, phenomenal in their
15:51
own right. But um, in a way
15:54
this discovery should set us all sort of
15:57
yawning with. Well that's what we thought.
16:00
Andrew Dunkley: Um, well the previous storey probably too,
16:02
but it's too big not to make you go
16:05
wow.
16:07
Professor Fred Watson: Yeah, yeah, this goes wow too but for
16:09
slightly different reasons. So um, when,
16:13
when astrophysicists think about the planets
16:16
going around other stars, they
16:19
basically make assumptions about
16:22
the raw materials that those planets
16:25
were made of. And, and their
16:28
assumptions come from measurements
16:31
of the uh, heavy
16:34
element content in the parent
16:36
stars. So if you, if uh,
16:39
you observe a star, uh, you can use
16:42
spectroscopy to look at the
16:45
distribution of elements in its
16:47
atmosphere. Sometimes molecules as well, if
16:49
it's a cool star. But usually it's just the
16:52
atomic elements. And uh, this goes back to
16:55
the beginnings of astronomical spectroscopy.
16:57
The idea of you know, splitting the light up
16:59
into its rainbow of colours and looking for
17:01
the signature of different elements in it.
17:03
That goes back to 1869 I think,
17:06
um, might even have been 59 when um,
17:09
William Huggins made the first
17:12
observations of the spectra of stars.
17:15
Um, so Huggins
17:18
basically said, well we know what the
17:20
signature of elements is on Earth. In fact
17:23
some work done by Kirchhoff and Bunsen before
17:26
that had worked out what the elements were
17:28
present in the sun were. Uh, and Huggins
17:31
did it. You're going to cheque up on me here.
17:33
Is it 1869 or 1859?
17:36
Andrew Dunkley: Um,
17:38
186. Well there's a few things
17:41
on the list that involved it, but
17:43
1860s is generally the accepted
17:47
time frame. Um, yeah,
17:50
I think he used uh, Doppler shift to measure
17:53
the radial velocity of Sirius in
17:55
1868. And uh, he
17:57
specifically identified absorption lines in
18:00
stellar spectra, including veg in
18:03
1863 and 1864.
18:05
Professor Fred Watson: Yeah, yeah. So, so that, that's
18:08
not the right time. That's when we've, that's
18:10
how long we've known about the elements that
18:13
make up the atmospheres of stars. Most of it
18:16
is hydrogen. Um, and,
18:19
but that's what basically what is
18:22
the raw material or the fuel that makes stars
18:24
burn or they don't burn but they, they
18:27
have nuclear fusion which keeps them going.
18:30
Um, but uh, it's the sprinkling
18:33
of the other elements that uh,
18:36
make up the atmosphere of the star and they
18:38
vary depending on the temperature and
18:41
category and age of the star. We measure
18:44
something called metallicity. And you and I
18:46
have chuckled before about the fact that
18:49
uh, oxygen's astronomy. Yeah.
18:52
Astronomers call everything heavier than
18:55
uh, either hydrogen or helium. Everything
18:57
else is a metal. Including oxygen. That's
18:59
right. And neon and things like that.
19:03
Um, it's just a term that came about in
19:05
probably about the same time as Huggins was
19:07
working on it back in the 19th century.
19:10
Anyway, um, the metallicity is a measurement
19:12
of the richness in terms of the chemical
19:15
elements that are in the atmosphere of a
19:17
star. And so the
19:20
assumption has always been that if
19:23
you know, a star generates its own
19:26
solar system and that process takes place
19:28
simultaneously, the cloud of gas and
19:31
dust collapses into a star, uh,
19:34
which eventually heats up to the extent that
19:37
it. Nuclear fusion occurs as
19:39
it is with the sun. Uh, but the swirling
19:42
disc of material around it called the uh, the
19:45
protoplanetary disc, that stuff is where the
19:48
planets form. But the planets are basically
19:50
made of the same stuff as the star is.
19:53
That's the bottom line. So that's always been
19:55
the assumption that if we're observing
19:57
planets around other stars they must have the
20:00
same content. And that's in
20:02
terms of whether these planets are going to
20:04
be rocky or not. If you got lots of silicate
20:06
material, uh, in it, that would have come
20:09
from the silicon in the atmosphere of the
20:11
star. So all these things are inter layered.
20:14
Um, so that assumption has never been tested
20:17
until now. And that's why, that's
20:20
why this is a wow storey, uh, because uh,
20:23
this uh, is some observations
20:26
uh, of exactly as you've said, um, super
20:29
hot Jupiter. Uh, it
20:32
is uh, or an ultra hot Jupiter is
20:35
the technical term usually um,
20:37
abbreviated to uhj. So
20:40
uh, that's a great new term for us. An
20:42
acronym, an urge. An ultra hot
20:45
Jupiter. Uh, it's about 320 light
20:48
years away. It is called WASP
20:50
189B. WASP is I think the wide angle
20:53
search for planets if I remember rightly. Uh,
20:56
and um, it's um, because it's an ultra
20:59
Jupiter, um, the
21:02
temperature of its atmosphere is
21:05
ridiculously hot. Uh, you know it's measured
21:08
in thousands of degrees and that means
21:11
that the materials within it
21:14
ah, are vaporised, particularly
21:17
the rock forming elements like
21:20
magnesium, silicon, iron
21:23
and um, probably calcium and a few other
21:25
things as well. They're the things that make
21:28
up um, rocks if they're
21:31
cold, uh, but
21:33
this one has them in its atmosphere. And the
21:36
key point about this storey which
21:39
was led uh, from Arizona State University
21:42
along with an international team of
21:44
astronomers. The key point is
21:47
that the chemical makeup
21:50
of WASP18B exactly
21:53
matches its parent star. Uh, um,
21:56
and that is really you know, that's a kind of
21:59
smoking gun that tells us that we're on the
22:02
right track when we uh, when
22:05
we make the assumption that the material
22:08
in a planet around the other star,
22:11
the material of which that planet is made
22:13
will have the same, what we call chemical
22:15
abundances, the ratios of the, of
22:18
the different chemical elements to its parent
22:21
star. Which is important
22:23
information because it means we're on the
22:25
right track basically.
22:27
Andrew Dunkley: I'm going to ask the obvious dumb question
22:28
here though. Um, so we've discovered this
22:32
thousands um, of light years away with WASP
22:34
189B. Why didn't we know
22:37
that in regard to our own sun and Earth?
22:41
Professor Fred Watson: Uh, yeah, well we do, um, okay,
22:44
that's a good question. We do, um, and
22:46
so but it's never been tested for
22:50
what you might call the general case. And an
22:52
ultra hot Jupiter is so different from
22:54
anything in the solar system that it's
22:57
reassuring that you get the same answer
23:00
from that as we do from our own solar
23:03
system. That's a great question.
23:04
Andrew Dunkley: Yeah. Uh, this um, particular
23:07
planet is uh, double the size of
23:09
Jupiter. It's 1.99
23:12
planetary masses. Um, when you compare
23:15
it to Jupiter um, it was only
23:18
discovered five, six years ago.
23:21
So um, it's a new one. Um,
23:24
but it's um, 1.619 times
23:28
bigger than Jupiter in terms of its radius.
23:31
So it's a big, it's a monster, isn't it?
23:34
Professor Fred Watson: Uh, yes it is.
23:37
Some of the planets that we find orbiting
23:40
other stars are pretty crazy.
23:42
Andrew Dunkley: I said thousands of light years. It's 320.
23:44
Professor Fred Watson: Yes, 300, that's right.
23:47
That's okay, we'll let you off that.
23:49
Andrew Dunkley: Yeah,
23:51
I'm not quite with it today. I
23:54
don't know how that's different from any
23:56
other day.
23:56
Professor Fred Watson: But um, well funnily enough neither
23:59
am I because I can only hear through one ear
24:02
at the moment. Uh, I
24:05
hate that. Yeah.
24:06
Andrew Dunkley: One of the pitfalls of radio is you, you
24:09
build up a lot of earwax fast and if you
24:11
don't keep up up cleaning you go
24:14
deaf and then you have to go to the doctor
24:17
and get syringed. It's not very pleasant.
24:20
Uh, I'm sure people really wanted to hear
24:22
that.
24:22
Professor Fred Watson: Yes, that's right.
24:23
I'm thinking that. But you know the stuff
24:25
that comes out of your ear is, has the same
24:28
chemical mix as the stuff that's
24:31
inside the sun in some remote way.
24:34
So I'm sure there is a link with astronomy.
24:37
Oh gosh.
24:38
Andrew Dunkley: Um, the article, if you want to read it
24:39
it's@scitechdaily.com where you can read the
24:42
paper in Nature Communications.
24:45
This is Space Nuts with Andrew Dunkley and
24:47
Professor Fred Watson Watson.
24:51
We choose to go to the Moon
24:53
Professor Fred Watson: in this decade and do the other
24:55
Andrew Dunkley: things not because they are easy but
24:58
because they are hard Space nuts.
25:01
And we are going to the Moon right now
25:03
because something happened. It got hit by a
25:05
big rock and it's
25:08
created massive
25:11
crater. I mean this is a, this is a very
25:13
recent development Fred Watson.
25:15
Professor Fred Watson: Yes it is. Uh, it's um, one
25:18
that comes uh, about or a discovery that
25:20
comes about because of our ability uh,
25:23
to detect changes on the Moon given ah,
25:26
that the Lunar Reconnaissance Orbiter
25:29
ah, uh, is
25:32
still photographing the lunar surface and
25:35
it's been doing that. I can't remember when
25:37
Lunar Reconnaissance Orbiter was uh,
25:40
commissioned, uh, when it came on stream, but
25:42
it's quite a few years ago. It's probably a
25:44
decade ago now. I'm sure you'll tell me in a
25:46
minute. Um, LRO
25:49
as it's called. And because it's doing this
25:52
sort of continuous survey we can
25:54
see when something changes. And
25:57
in the late northern uh hemisphere spring
26:00
of 2024 uh something did
26:03
change. Uh, a rock, um,
26:06
probably several metres
26:09
in diameter, maybe even tens of
26:12
metres, um, uh, hit the
26:15
moon and produced a crater
26:17
225 metres across uh
26:20
on the surface of the Moon. Um,
26:23
and that is something that
26:26
we know happens. We expect this to happen
26:28
because we get bombardment by
26:31
objects that size of the Earth's atmosphere.
26:33
They're relatively, relatively rare.
26:35
Something like um, you know it will
26:38
be once every 30 years or so for a 10
26:41
metre object to uh, hit the
26:43
Earth's atmosphere. Probably explode in the
26:45
Earth's atmosphere. But with the Moon not
26:47
having an Atmosphere go straight down to the
26:49
surface and what do you get? You get a
26:51
crater. Um, and it's
26:53
apparently, uh, this is by far
26:56
the largest new crater that's
26:59
been found during the lifetime of the Lunar
27:01
Reconnaissance Orbiter Mission. The last
27:03
record was 70 metres across. This one's
27:06
much more. Yes, and suggests, um,
27:09
that, that this is a much rarer object. And
27:12
one of the reasons I, I like this storey,
27:15
Andrew, is that it has echoes of something
27:17
we've just heard about this last week.
27:20
Andrew Dunkley: The meteorite flashes that the
27:23
Artemis crew saw.
27:24
Professor Fred Watson: Yeah, exactly.
27:25
Andrew Dunkley: They saw things hitting the moon.
27:27
Professor Fred Watson: Yes, indeed. And they saw these flashes that,
27:30
um. And that's what they are. And so, um,
27:32
this one would have been a very big flash.
27:34
Uh, I'm not sure whereabouts on the moon it
27:36
is as to was on the Earth, uh,
27:39
facing side of the moon or not. Uh, but
27:42
it made, certainly made. It would have made
27:45
quite a bright flash. Uh, and
27:47
you know, we've known for more than, well,
27:50
60 years, uh, that these things do happen.
27:53
It took a while before people worked out
27:55
that, uh, and before the Apollo era, that
27:58
people worked out that these were caused by
27:59
impacts rather than, uh, rather than by
28:02
volcanic activity. I remember old Patrick
28:04
Moore, the doyen of space communicators in,
28:06
in the uk. I, um, remember him.
28:10
In fact, one of the things he did research on
28:12
was what he called TLES, transient lunar
28:14
events. But nobody knew back in the 40s and
28:17
50s whether these were volcanic eruptions or,
28:20
uh, meteorite impacts. Now we know and,
28:23
um, we've almost seen them happen before our
28:25
eyes with this newly discovered crater.
28:28
Andrew Dunkley: Yeah, and It's a whopper, 225 metres
28:32
across. So, um.
28:35
Yeah, and I suppose you could have a guess at
28:38
how big the rock that hit it was, what, 10
28:39
metres, you think?
28:40
Professor Fred Watson: Maybe something. Yeah, yeah, that sort of
28:42
order.
28:43
Andrew Dunkley: And, and would that rock still be on the moon
28:44
or did it get obliterated? Because it gets
28:46
really hot, the impact, it just melts
28:48
everything and then it freezes instantly or
28:50
something, doesn't it?
28:50
Professor Fred Watson: That's, that's right. Vaporised. It would
28:53
have been vaporised. Right. The energy of
28:54
impact, um, you know, this is coming in at 30
28:57
or 40 kilometres per second.
29:00
Um, and when it hits rock, I mean, we know
29:02
from simulations of these meteorites,
29:05
uh, small asteroid impact on Earth, that
29:08
the crust, uh,
29:11
turns literally into a liquid, uh, behaves
29:14
like a liquid. Um, I've got a simulation that
29:16
I showed on yesterday to a class of physics
29:19
students at the University of Wollongong, uh,
29:22
um, online. Um, it's a Simulation that shows
29:25
what would have happened to the Earth's
29:26
surface with the, uh, 10 kilometre
29:29
diameter asteroid that took out the
29:31
dinosaurs. And it. In, you know,
29:34
you got within the first
29:36
60 seconds, you've, you've got both
29:39
a hole 20 kilometres deep
29:42
and a mountain range 20 kilometres high
29:45
being formed within the first few seconds.
29:48
Andrew Dunkley: Just mind blowing.
29:49
Professor Fred Watson: Absolutely. And so, um, yes,
29:52
this, this new crater, in fact one of the
29:55
salient points about it is it's quite, it
29:58
is actually quite deep. It's 43 metres deep.
30:01
Um, the, there's a nice article about this in
30:04
Universe Today that makes the point that
30:07
40, um, three metres deep, that means the
30:09
walls of the crater would be steep enough
30:12
that you'd struggle to stand on them. Um, and
30:15
so, um, uh, it's got, uh, yes,
30:19
quite a significantly deep object.
30:21
Andrew Dunkley: Indeed it is, yes. Um, and as
30:24
Fred Watson said, you can read about
30:25
that@universetoday.com and for the
30:28
record, uh, the, uh, Lunar
30:31
Reconnaissance Orbiter started observing the
30:33
moon close in 2009.
30:36
Professor Fred Watson: Really? 16, 17 years.
30:39
Andrew Dunkley: Yeah.
30:39
Professor Fred Watson: Fantastic.
30:40
Andrew Dunkley: It's impressive.
30:42
All right, uh, that brings us to the end of
30:45
the programme. Fred Watson, thank you so
30:47
much.
30:48
Professor Fred Watson: Time flies when you're having fun does,
30:50
doesn't it?
30:52
Andrew Dunkley: We'll be back. We'll be back and we'll see
30:54
you then.
30:55
Professor Fred Watson: Sounds great. Thanks, Andrew.
30:56
Andrew Dunkley: Thank you, Fred Watson. Professor Fred Watson
30:58
Watson, astronomer at large. Don't forget to
31:00
visit us online while you're out and about or
31:01
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There's lots of goodies in there. It's coming
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yourself a hoodie. I mean, you can look like
31:39
a thug and be an astronomer at the same time.
31:42
Fred Watson does. And, um.
31:47
Damn, I should.
31:48
Professor Fred Watson: No.
31:48
Andrew Dunkley: I usually have a crack at Huw, but he's not
31:51
an astronomer. Um, but yeah. And thanks to
31:53
Huw in the studio, who couldn't be with us
31:55
today, he's once again in police custody
31:57
because they found a giant. A giant,
32:01
I'm saying, slingshot in his backyard, aimed
32:03
at the moon. Oh. Oh,
32:06
yeah. And from me, Andrew Dunkley. Thanks for
32:08
your company. We'll see you on the next
32:10
episode of Space Nuts. Bye. Bye.
32:13
You've been listening to the Space Nuts
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