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Exocomets, Martian Revelations & Habitable Zones Beyond · Space Nuts: Astronomy Insights & Cosmic Discoveries

0:00
Andrew Dunkley: Hi there. Look who's back.
0:03
Yes, it's me. Back from,
0:06
uh, everywhere we went. Everywhere. Anyway, I
0:08
won't bore you with all of that. Andrew
0:10
Dunkley here. Great to have your company on
0:12
another episode of Space Nuts.
0:14
And coming up on today's show, we will
0:17
be diving into the weird world
0:20
of exo. Asteroids or
0:23
exocomets or whatever they are. 30, uh,
0:26
one atlas to be exact. And it turns
0:29
out it's a bit of a strange one. Uh, also in
0:31
Insight, uh, the Insight mission is
0:34
unravelling Mars's secrets, uh,
0:37
particularly its deep, dark past. And believe
0:39
me, it's a little bit ugly. And
0:42
a galactic habitable zone.
0:45
Is there such a thing? What does it mean? And
0:48
what are we going to find there? We'll find
0:49
out on this episode of space nuts. 15
0:52
seconds. Guidance is internal.
0:55
Voice Over Guy: 10, 9. Ignition
0:57
sequence start. Space nuts. 5, 4,
1:00
3. 2. 1, 2, 3, 4, 5.
1:05
Space nuts. Astronauts report it feels good.
1:08
Andrew Dunkley: And joining us to do all the unravelling
1:11
is Professor Fred Watson Watson, astronomer
1:13
at large. Hello, Fred Watson.
1:15
Professor Fred Watson: Welcome back, Andrew. It's, um, a, uh, treat
1:18
to see your smiling face.
1:21
Andrew Dunkley: It's a treat. It's a treat to be back and
1:23
doing this after it's been three months. I
1:25
can't believe that, uh, it's been.
1:29
Judy and I were only saying today we cannot
1:31
get our heads around the fact that we're away
1:33
for three months because it doesn't feel like
1:34
it. It's just, you know, it
1:37
went so fast. But, gee, we had a good time,
1:40
Fred Watson. We had an amazing time. Um,
1:43
unfortunately, did not get to see the
1:45
northern lights. And that was
1:48
one of my. But I might get another
1:50
opportunity. You know, it's not the last time
1:52
we'll go away somewhere, so fingers crossed.
1:54
But, um, even as far north as, uh,
1:57
North Cape, the northern tip of Europe, right
2:00
up inside the Arctic Circle, did not see a
2:03
thing. Uh, probably because it was nearly
2:05
daylight every minute of the day and night.
2:08
So that doesn't help.
2:12
Um, but, yeah, a terrific holiday. I don't. I
2:15
wouldn't know where to start to tell you
2:16
about it. I know I posted a lot of pictures
2:18
that people saw, uh, every time we went away
2:21
or went somewhere, um, but just
2:24
saw some amazing things, met some amazing
2:26
people, had some amazing moments. Just,
2:29
um, little things that we didn't expect.
2:31
Like, uh, the captain of the ship suddenly
2:34
deciding at the last minute to take us up,
2:36
um, Prince Christian Sound
2:39
in Norway, which is somewhere where not
2:42
many people get to go. And the only way to
2:45
get there is by ship. And it is Full of
2:48
icebergs and wildlife and
2:51
just, um, glacier after glacier
2:54
after glacier right there in front of you.
2:57
Um, it's indescribable. Uh, it's just the
2:59
most amazing scenery. Uh, we sat
3:02
up on the deck for seven and a half hours
3:05
straight just taking it all in. We did not
3:07
move. It was that captivating.
3:11
Um, that was one of the highlights.
3:13
Um, Namibia was amazing. Loved
3:16
Namibia. Uh, we,
3:19
um, loved Scotland. Loved Edinburgh,
3:22
Fred Watson. What a terrific place. Um, we
3:25
had porridge for breakfast and.
3:27
Professor Fred Watson: You have haggis for lunch, didn't you?
3:29
Andrew Dunkley: And had haggis for lunch, which, surprise was
3:31
surprisingly nice. I, you know, you hear
3:33
horror stories, but it was actually quite
3:36
tasty. Really enjoyed it. And,
3:38
um, look, the countries we visited were,
3:41
were many. Uh, the highlights were
3:44
numerous. I wouldn't, I could talk for
3:47
hours, which probably wouldn't work well on a
3:49
space podcast. So I won't, um,
3:53
I won't say too much more about that.
3:54
Although at Tenerife we did see the
3:57
observatory up, um, above the snow
4:00
line there. Above the, um, uh,
4:03
tree line, actually, not the snow line. Um,
4:06
you drive up the hill, you've probably done
4:08
this bread, and all of a sudden there's no
4:10
vegetation, it's just gone.
4:13
And, um, there's an observatory up there
4:15
which is primarily a solar observatory,
4:18
so.
4:18
Professor Fred Watson: That's right, yeah. Got to have. So Tad is
4:21
the name of the mountain, Katie.
4:22
Andrew Dunkley: That's right.
4:22
Professor Fred Watson: Yep, yep, yep.
4:23
Andrew Dunkley: Yes.
4:25
But, uh, here we are back again.
4:27
Professor Fred Watson: Um, yeah, I do have a question for you about.
4:29
Andrew Dunkley: Oh, ah, yeah.
4:31
Professor Fred Watson: Andrew, did you. Did you run into any space
4:34
nuts? I did,
4:36
I actually did.
4:38
Andrew Dunkley: Um, one in particular who I ran into
4:41
in a toilet on a ship. On our
4:44
cruise ship. I was walking out
4:47
and this, he said, um, are you Andrew
4:48
Dunkley? And I went, yes, he said, he
4:51
said, I'm a Space Nuts listener, he said. And
4:54
I remember he did message. Message me to say
4:56
he'd be on the cruise and getting on in Dover
4:58
and I'd forgotten about that. And, uh, yeah,
5:00
we ran into each other in passing. So,
5:03
um. And as always, I've forgotten his
5:06
name and I apologise for that. But it was
5:08
nice to catch up. So, yes, we did. No, it ran
5:11
into a few. A few people I did pass, uh, or
5:14
speak to on the ship knew me, but I don't
5:16
know if they knew me from radio or from the
5:19
podcast. We never really clarified that. But
5:22
yeah, it was, uh, it was quite extraordinary.
5:25
Um, but if you jump on Facebook, all
5:27
my photos are on my Facebook page and
5:29
Instagram So you should be able to see most
5:31
of what we did. So I don't take up the rest
5:34
of the show talking about it,
5:36
although I'll probably, probably have times
5:39
where I'll make references to things we saw
5:41
and didn't. Yeah.
5:44
Now, um, we've got a lot to talk about, but
5:47
one of the things you do want to discuss and
5:49
I think you did that with Heidi. Oh, and I'd
5:51
like to say just my, um,
5:55
sincere thanks to Heidi for stepping up and
5:57
covering the last few months. It was a, it
5:59
was a big job and she did, did fantastically.
6:02
The feedback I've been getting, uh, even
6:04
while I was away was, uh, was glowing. So
6:07
well done, Heid Heidi and thank you, Much
6:09
appreciated. Uh, and you
6:12
talked to her last week and you want to
6:13
mention again, the Australian Dark sky
6:15
alliance is looking for some support.
6:18
Professor Fred Watson: That's right. So if you're not
6:21
either resident in or a citizen of Australia,
6:24
you can zone out for a minute while I talk
6:26
about a petition which the Australasian
6:29
Dark sky alliance, uh, is trying
6:32
to get put up to the, the federal government,
6:35
the government of Australia, in order to
6:37
put legislation in place to limit light
6:40
pollution, to actually restrict it as an
6:42
environmental issue, not just for
6:44
astronomers, but for wildlife, for human
6:46
health, all of the above. So if you do fall
6:49
into one of those categories, uh, the place
6:51
to go is their website, which is all one
6:53
word,
6:54
australasiandarkskyalliance.org
6:58
uh, and so
6:59
australasiandarkskyalliantiance.org will take
7:02
you to their website, which on the front page
7:04
has instructions on how to sign the petition.
7:07
And you've got till September 19th. And
7:09
thank you for that plug and.
7:12
Andrew Dunkley: Uh, my great pleasure. Uh, and hopefully the
7:15
politicians will listen. Hopefully you get
7:17
the numbers. That's the most important thing.
7:21
And it's a really important thing. I mean,
7:23
uh, we've talked about light pollution
7:26
many, many times over the years. And it's
7:29
just one of those growing problems,
7:32
uh, which doesn't seem to get a lot of
7:34
attention because no one really thinks about
7:35
it as a problem. I suppose that's the
7:38
problem.
7:39
Professor Fred Watson: It is, uh, uh, on the other hand, it is one
7:41
of the easiest to fix because flick of switch
7:44
actually does it. Um, but you're right, I
7:47
mean there's certainly regulations in regard
7:49
to noise pollution, uh, and of course every
7:52
other kind of pollution. We're seeing
7:54
regulation coming in on plastics pollution.
7:56
But light pollution is the orphan pollution
7:59
at the moment. And it's an important one.
8:00
It's one that's more important than Most
8:02
people realise, and one statistic, uh, you
8:05
might not be aware of this Andrew, but light
8:06
pollution is increasing globally at
8:09
10% per year. So that
8:12
comes from cities and science. Yeah, we know
8:14
uh, that the stars are disappearing at that
8:16
rate, 10% a year, it's very
8:19
ugly indeed.
8:21
Andrew Dunkley: That is, that's not good at all. And having
8:23
witnessed now 24 hour day sunlight, I
8:26
do understand how it could mess you with your
8:28
brain. So it's not good for human
8:31
healthy. Uh, so that's
8:33
australasiandarkskyaalliance.org
8:37
uh, 10,000 signatures by the 19th
8:40
of September if you will.
8:42
Uh, right, our first topic, Fred Watson,
8:45
takes us uh, into the realm of uh,
8:47
interstellar objects. 31 Atlas.
8:50
Um, now I did see this one pop up in the
8:53
news while I was away. I did try to keep in
8:55
touch but um, when you're moving into
8:57
different time zones of different parts of
8:59
the world, your news suddenly changes,
9:02
which is a little bit weird. Uh, but
9:04
31 Atlas, um, this one was only a recent
9:07
discovery and it's hammering way through our
9:09
ah, system as we speak. Uh, but they've been
9:12
uh, able to analyse it thanks to the James
9:14
Horace Webb Space Telescope. And this one's a
9:17
little bit unusual.
9:19
Professor Fred Watson: Uh, that's right. And um, because all the
9:22
text you've read is in uh,
9:25
Arial, uh, font, you wouldn't
9:28
have no way of knowing that it's actually 3I
9:30
Atlas. Holy
9:32
circumstances. 3I
9:35
being the third interstellar, the third
9:37
interstellar, uh, object to pass through the
9:39
solar system and uh, Atlas, of course, and
9:41
then the facility that discovered it.
9:43
Andrew Dunkley: I'm using jet lag as an excuse.
9:46
Professor Fred Watson: It doesn't matter. Even if you weren't jet
9:48
lag, you wouldn't have known because now.
9:52
Andrew Dunkley: 31.
9:54
Professor Fred Watson: Yeah, but it's 3i. Never mind.
9:57
You see that's the advantage of uh, times,
10:00
Times New Roman. That would, that would solve
10:03
the problem. Um, anyway,
10:05
this is being observed uh, as it flies by
10:08
the solar system. It's closest to the sun if
10:11
I remember rightly, on the 29th of October.
10:14
So unlike uh, uh, unlike
10:16
Oumuamua, which was one eye, the first
10:19
um, interstellar object, uh, we
10:22
didn't catch up with that until it was on its
10:25
way out of the solar system Atlas, uh,
10:28
uh, we found on the way in. Uh,
10:31
and one reason for that is that it's a much
10:34
bigger object. Um, I think um, the
10:37
best estimate we got for the size of
10:39
Oumuamua was something like 40,
10:43
maybe 100 metres long, something of that
10:45
sort. I can't remember the exact number but
10:46
this thing is thought to be about 20
10:48
kilometres across um and
10:51
it's despite um the
10:53
prognostications of Avilob who wanted uh
10:56
it to be an interstellar spacecraft.
10:59
It's behaving exactly like a comet in that
11:02
it's uh, as it approaches the sun the
11:05
material that it's made of which is a mixture
11:07
of ice and dust uh that
11:10
heats up the ice turns into a vapour, the
11:13
dust gets released and it generates what we
11:15
call a coma um coma is just a word meaning
11:18
hair and it's uh, a sort of fuzzy bit of
11:21
the uh, of the comet and um,
11:24
develops a tail and indeed three eye Atlas
11:26
has done that. Um it's uh,
11:29
what's of interest uh of course is
11:32
that there are mixed in with the dust
11:35
there are atoms and in fact molecules of the,
11:38
of the material that binds it together, the
11:40
ices that bind it together. And it's not just
11:42
water ice. We know that comets are made
11:44
mostly of water ice. Water as we've said many
11:47
times on space knots is the most common
11:50
two element uh molecule in the universe.
11:53
Uh so it's natural that we should find water
11:56
in comets. But there's also
11:59
basically uh carbon dioxide, CO2, carbon
12:02
monoxide CO uh and those
12:04
uh gases are revealing their presence by
12:07
their spectra. Uh the rainbow spectra that
12:10
you can analyse the light that's coming from
12:13
them and indeed uh, exactly as you've said
12:16
the James Webb Space Telescope is
12:19
being uh used by a number of
12:21
authors mostly in the United States.
12:24
Uh Goddard Space Flight Centre and the
12:26
Catholic University of America are two of the
12:28
organisations represented. So you've
12:31
got carbon monoxide, carbon dioxide,
12:33
you've got something called carbonyl
12:35
sulphide. Uh all of these are
12:38
ah, not unexpected because that's what
12:41
we find in comets that belong to the solar
12:43
system. But here's the rub,
12:47
um and it's the ratio of these
12:50
molecules to each other that is
12:53
uh the peculiarity of three I atlas
12:56
uh and in particular the ratio
12:59
of carbon uh dioxide to water
13:03
is actually eight to one. So eight
13:06
parts of carbon dioxide to one part of water
13:10
and that's higher than any other comet that's
13:12
ever been seen and way, way above the normal
13:15
value um, which is I think
13:18
two or three to one, something like that. I
13:20
can't remember the exact number. Um however
13:23
carbon monoxide has uh
13:26
a ratio with water that's more or
13:29
less the same as ah, um solar system
13:32
comets. It's 1.4. So
13:35
there's a puzzle uh why is the carbon
13:37
dioxide, so much more abundant. Uh, and
13:40
of course, as always, when faced with a
13:42
puzzle, um, astronomers start trying
13:45
to work out what's going on, uh, and
13:49
they basically think
13:51
that they have sort of solved
13:54
it. Um,
13:57
um, it's. One possibility
14:00
is if you imagine the host
14:03
star system in which this object was created
14:06
and it would have formed like the, uh, solar
14:09
system's comets, probably in an Oort cloud
14:11
like the one we have around our solar system,
14:14
which is made of, uh, cometary bodies,
14:17
uh, which eventually fall in towards the
14:18
inner solar system. And that's when we see
14:20
them. Uh, there's a suggestion that if you've
14:23
got very high levels of ultraviolet
14:27
radiation, uh, from that
14:29
host star, and that would be the case if it
14:32
was a young and very massive star, um,
14:35
that apparently could change this ratio of
14:38
water to carbon dioxide.
14:40
Um, and another comment that's been
14:43
suggested is that maybe, um,
14:45
it's uh, a part of that, um,
14:48
of the solar system in which it was born.
14:51
That's a long way from the host star,
14:55
uh, and above the host star's carbon
14:57
dioxide ice line. So beyond
15:00
a certain distance you get more carbon
15:03
dioxide in relation to
15:06
water. Uh, and, you know,
15:09
that's another possibility. There's several
15:11
more that are being thought of. But, uh, the
15:14
bottom line is, nearly as always with stories
15:16
like this, Andrew, what we need is more
15:18
observations. Uh, and uh, you know,
15:21
we don't have very long before it will get
15:24
too faint to observe. It'll be probably
15:27
next year when it starts, um, really
15:29
disappearing out of the solar system. But,
15:31
uh, so we've got this golden opportunity to
15:34
analyse it and, and investigate it. And
15:36
that's exactly what's happening.
15:38
Andrew Dunkley: How, how visible is this one going to be as
15:41
it reaches the inner sanctum of
15:44
our solar system?
15:44
Professor Fred Watson: Yeah, not, not that visible
15:47
because, um, in fact, I don't have a figure
15:49
for its magnitude, the gobbledygook number
15:51
that astronomers use for brightness. Uh, but
15:54
it's. It's certainly, um, very much the
15:56
province of big telescopes. The thing is, uh,
15:59
its nearest approach to Earth, uh,
16:02
um, I can't remember. It's more than one
16:05
astronomical unit, I think, which is the
16:06
distance between the Earth to the sun. I
16:08
can't remember the exact distance. Uh,
16:11
it's not that close to the sun either. Uh,
16:14
and I think I'm right in saying
16:17
that when it's closest to the sun, we can't
16:19
see it because it's in the same direction.
16:21
It's sort of passing behind the Sun. Um, that
16:24
was one of the comments that ah avilaeur made
16:27
uh suggesting that maybe uh when it was at
16:30
its brightest um its orbit had been chosen so
16:32
that we couldn't see it it when it was at its
16:34
brightest um and the other thing he pointed
16:36
out was that it passes very close to or
16:39
closeish to Venus, Mars and Jupiter.
16:42
Um and um, you know the suggestion was that
16:44
there might be intelligent design behind
16:46
that. But uh, I think he's the only person
16:49
in the astronomical community he thinks.
16:51
Andrew Dunkley: That he might be
16:54
right. Uh, you got to give him credit
16:57
though.
16:57
Professor Fred Watson: He's always um. Yeah we need ideas like
17:00
that. Absolutely.
17:01
Andrew Dunkley: Yeah. Yeah. Okay so uh,
17:04
and is this one honking along like the others
17:08
at a.
17:08
Professor Fred Watson: Greater rate of knots, 60 something
17:11
kilometres per second which is kind of one of
17:13
the things that tells you that it doesn't
17:15
belong to our solar system. It's going too
17:16
fast.
17:17
Andrew Dunkley: Right, There you are. Okay, uh you can read
17:20
up on that one uh@universetoday.com
17:23
uh3iatlas
17:26
Got it. This is Space Nuts with Andrew
17:29
Dunkley and Professor Fred Watson Watson.
17:36
Space Nuts, our uh next story. Fred Watson
17:39
takes us to a place I rarely
17:41
mention. Uh it is the red planet Mars.
17:45
Uh INSIGHT has uh been um
17:47
sort of examining some of the secrets of Mars
17:50
and come up with uh new information
17:54
that kind of might surprise people about uh
17:57
Mars's deep dark and ugly past.
18:00
Um, there's been a few revelations.
18:03
Professor Fred Watson: There have, yes. Um, I mean INSIGHT is the
18:05
gift that keeps on giving really. Um because
18:08
it switched off in 2022. Uh
18:12
um it's ah a spacecraft that
18:14
landed near Mars's equatorial region.
18:17
Uh I think in about 2019 was when
18:20
it uh touched down um and you might
18:23
remember we discussed a lot the instruments
18:25
that are on board it because one of them was
18:27
a seismometer uh which has been incredibly
18:30
successful and the other one was the interior
18:33
thermometer which was incredibly unsuccessful
18:35
because they were trying to drill a hole to
18:38
put this thermometer down under the surface
18:41
of uh Mars and I think can't remember what
18:43
happened. The drill correct. Kept breaking or
18:44
something um unsatisfying
18:47
happened uh until that part of the experiment
18:50
was not as successful but the seismograph has
18:53
done its job and um the results from
18:56
that keep um on being reanalysed
18:59
uh because as time goes on we've got
19:02
many more analytical facilities at our
19:04
disposal which we didn't have before. Uh and
19:07
um, you can now look at these seismic records
19:09
with a lot more meaning and
19:12
what's been discovered. It's actually um,
19:15
from an analysis of eight seismic
19:18
Events, uh, uh, two
19:21
of which were probably caused by
19:23
meteorite impact on Mars.
19:27
Remember um, that the two mechanisms, because
19:29
Mars doesn't have plate tectonics, it's
19:31
called a single uh, crust. Um,
19:35
it's uh, stretching and shrinking of the
19:38
crust and sort of rift valleys forming and
19:40
things like that that give you the seismic
19:42
events or meteorite impacts. And two of
19:45
those seismic events as I said, were
19:47
meteorite impacts. But um,
19:50
it's the way that the uh,
19:52
relative frequencies of the vibrations, the
19:55
uh, seismic vibrations, the relative
19:57
frequencies of these, uh, that
20:00
allows people to basically
20:02
examine the interior of Mars, uh,
20:06
in a very intelligent way. Um,
20:09
so you look for higher frequency waves
20:12
compared with uh, low frequency waves. And
20:15
basically uh, that tells you
20:18
uh, about the length of transmission time
20:21
uh for these different waves, how long it
20:23
takes you to get from the site of impact,
20:25
wherever that is, uh to the seismograph.
20:28
And uh, one of the authors uh, of this
20:30
work. I um, think there's ah, certainly
20:33
authors at Imperial College London and
20:36
uh, other institutions, uh, but one of the
20:39
authors m made a comment, um, which I
20:41
liked. These signals show clear signs of
20:44
interference as they travel through Mars's
20:46
deep interior. That's consistent
20:49
with a mantle full of structures of different
20:52
compositional origins, leftovers from
20:55
Mars's early days. And what that means is
20:57
so the mantle is the region between the crust
21:00
of uh, Mars and its core,
21:03
its hot core. Uh, we've got a mantle on
21:06
Earth. I think Mars's mantle is rather uh,
21:09
deeper than ours relative to the diameter of
21:11
the planet. Um but what they found is that
21:14
the mantle isn't a sort of uniform, um,
21:18
uh, paste of semi
21:21
solid rock, uh but it has
21:23
structure in it. Uh, and that structure
21:26
is thought to come from uh,
21:29
events that took place during Mars
21:32
origins. Uh and in fact what they're
21:34
suggesting is that um,
21:39
when Mars was being formed about
21:42
4.5 billion years ago, um,
21:44
it was at a time as we've talked about it
21:47
before. Not long after that there was the um,
21:50
what's it called, The Late Heavy Bombardment,
21:53
uh when there was a lot of stuff careering
21:55
around the solar system. Big objects the size
21:58
of uh, many planets really banging into
22:01
everything else. And the suggestion
22:04
is that at that period
22:07
some of these planetoids or planetesimals,
22:10
uh actually collided with Mars and
22:13
basically melted parts of Mars,
22:16
uh into oceans of
22:19
molten magma. Uh, and
22:22
then you find that these
22:25
regions cool, but
22:28
when they're cooled they have
22:31
a different structure from the stuff that
22:33
didn't get clouted and melted, uh, by
22:35
an impact so what you're doing is you're
22:38
differentiating between different zones of
22:40
Mars's mantle and what they're saying
22:43
is that what they're detecting with this uh,
22:46
inhomogeneity in Mars's mantle
22:49
is evidence of these, what they describe as
22:51
compositionally distinct chunks of material.
22:54
Uh so um, you know Mars
22:57
as mantle has got some bits that were never
23:00
reheated and others that were reheated after
23:03
the planet's formation by these collisions
23:06
probably molten, uh then they hardened and
23:09
they crystallised and that gives you a
23:11
different structure which is what's now been
23:13
seen. So um, it's ah, you know
23:16
one of the comments, uh, the same author, uh,
23:19
uh, who I just um, I just uh, mentioned
23:22
most of this chaos likely unfolded in Mars
23:24
first 100 million years. The fact that we can
23:27
still detect its traces after 4.5 billion
23:30
years shows just how sluggishly Mars's
23:33
interior has been churning ever since. Uh
23:36
unlike the Earth's which is much more active.
23:39
So yeah, um, the Mars story from
23:42
Insight keeps on amazing us. We keep
23:45
uh, discovering new facts about it and um.
23:48
Long may it continue Andrew.
23:50
Andrew Dunkley: Yes, yes, hopefully. Um,
23:52
and there's so much more to learn. This is
23:55
what I love about uh, these inner
23:58
planets uh, and the outer planets as well.
24:01
The more we look at them and the more we
24:02
analyse the data that we're receiving from
24:05
various missions, the more interesting they
24:07
get and the stranger they get sometimes as is
24:10
the case with Mars in this particular
24:13
situation. So uh, yeah it's a fascinating
24:15
place. Uh, cosmosmagazine.com
24:18
is where you need to go to uh, find out more
24:20
about that if you'd like to follow up on that
24:22
story. Andrew Dunkley here, Fred Watson
24:24
Watson there. You're listening to Space Nuts.
24:31
Professor Fred Watson: Space Nuts.
24:32
Andrew Dunkley: And uh, our final story today is about
24:35
a galactic habitable zone. Now we
24:38
know about the habitable zone in our own
24:40
solar system, uh, which is affectionately
24:43
called the Goldilocks Zone. And we
24:46
know about that because we're in it. That's
24:48
the only thing that keeps us alive really.
24:51
Uh, but Fred Watson, my question
24:54
first up is uh, are they talking about a
24:56
Goldilocks Zone on a galactic scale?
24:59
Is that what this is?
25:01
Professor Fred Watson: Yeah, effectively. Um, but um, it's
25:04
not the temperature that's not too
25:07
hot and m not too cold but just right as it
25:10
is in our Goldilocks Zone the temperature's
25:12
just right at this distance from the sun for
25:15
liquid water to exist. And we know it
25:18
does because we see it pretty well every day
25:20
uh, in our um, in Our
25:23
reservoirs of water, whether they're a
25:25
bathtub or a ah sea. Um, but
25:28
that's not what the galactic habitable zone
25:30
is about. And it is being called that the
25:32
GHz or GHz if you're on
25:35
the other side of the Pacific. Um,
25:38
it's uh, it's a region where
25:41
you might um, expect
25:44
to find more habitable planets
25:47
than nearer to the centre of our
25:50
galaxy or
25:53
further out towards the edge of the galaxy.
25:57
Uh and it basically
26:00
comes uh about uh. Because you can
26:03
analyse, you know we know a lot about the way
26:06
stars evolve. Uh and we know a
26:09
lot about the um, chemicals
26:13
um that have basically been found in
26:15
stellar interiors and their atmospheres. And
26:18
we can trace this history of stars very
26:21
accurately. Um and we can
26:24
also uh, look at the
26:27
orbits of stars around the centre of our
26:29
galaxy. Uh and we can work out to some
26:31
extent where they've come from because uh, we
26:34
think that the orbits of stars actually um,
26:37
ah, they actually change in a process called
26:39
stellar migration where
26:42
stars, orbits change around the centre of the
26:44
galaxy. Uh and you,
26:47
you know, you can find that they uh, move.
26:51
And so one of the studies, uh, one
26:54
of the um, comments that's come from
26:57
this particular study. It's actually an
26:58
international uh team of scientists who have
27:01
looked at this. Uh, this is published in
27:03
strongly in Astrophysics, one of the main uh
27:06
learned journals of astronomy. What they've
27:08
discovered is that
27:11
um, there's a five times
27:15
greater likelihood of
27:18
stars migrating from
27:22
one part of a
27:24
galaxy to another for
27:27
habitable planets, for stars that have
27:29
habitable planets compared to,
27:32
with a lack of any stellar migration. So
27:35
it's a slightly, this is a slightly obtuse
27:38
thing to look for. Um, but um,
27:41
what it says is, you know,
27:43
it's all about for example whether you
27:47
uh, are in a part of the galaxy
27:50
where your solar system could uh,
27:53
host gas giant planets because they
27:56
would basically have an effect on
27:59
the formation of the kind of rocky planets
28:01
that we think are the habitable one. Um,
28:04
so I might just read um, a ah, quote
28:07
from this paper. Uh, it's a little
28:10
bit uh, technical but um,
28:13
I think it's an interesting quote. It sort of
28:15
illuminates what we're talking about. Uh, in
28:17
this study we have significantly expanded
28:20
the exploration of the parameter space
28:23
defining the galactic habitable zone
28:26
compared to previous analyses present in
28:29
literature. Uh, our findings are particularly
28:31
relevant in the context of upcoming space
28:34
missions such as the ESA
28:37
PLATO mission, that's planetary transits and
28:40
oscillations of stars, the uh, ESA Aerial
28:42
Space Mission and large Interferometer
28:45
for exoplanets. That's life.
28:49
And these missions will deliver
28:50
unprecedented, um, data on planetary
28:52
properties, orbital architectures and
28:55
atmospheric concepts, compositions. So what
28:58
they're basically saying is, uh,
29:01
if you're going to look for habitable
29:02
planets, you want to be careful where you
29:05
look. Because if there is such a thing as a
29:07
stellar or a galactic habitable zone,
29:10
um, then, uh, we want to be looking there
29:13
if we're going to look for, uh, you know,
29:16
for uh, habitable planets. It's an old
29:19
idea, actually. The GHz, uh, or
29:21
GHz, uh, comes, goes back to the 1980s.
29:25
Um, and it's all about, you know, the um, the
29:27
formation of the heavier elements.
29:30
The ones that are basically work
29:33
like iron, silicon, uh,
29:36
oxygen, all of these elements. You've got to
29:39
form them. You've got to form them in the
29:41
right place in a galaxy. And uh, you've got
29:43
to then, uh, let that environment
29:46
breed these, uh, elements into molecules
29:49
which basically become the, um,
29:52
uh, precursors of life.
29:55
I'm sorry, that's the Gobbler book. Uh,
29:57
explanation.
29:59
Andrew Dunkley: No, fair enough. Um, so
30:02
does that mean that in our ongoing search for
30:04
exoplanets, we should be focusing on
30:07
the GHz areas?
30:11
Uh, or do we not really care where the
30:13
exoplanets are? Finding them is imperative
30:15
regardless.
30:17
Professor Fred Watson: Yeah, no, no, that's. That's exactly right.
30:20
That's exactly what these authors are saying.
30:21
We should be looking in the right place if we
30:23
want to find, uh, habitable planets.
30:26
Uh, and, um, uh, and indeed,
30:29
um, you know, the, the PLATO mission, for
30:31
example, is going to look at a million stars.
30:33
It's a bit like Kepler. The Kepler mission,
30:35
it was. It's finding planets by transits.
30:39
Uh, so that's going to scan a million stars
30:42
and, and you want to make sure you're looking
30:44
at them in the right place. That's the, uh,
30:46
bottom line.
30:47
Andrew Dunkley: Yeah. Although some would say, well, if we
30:50
focus only on those areas, we might miss
30:52
something important in the not so habitable
30:55
zones. You just never know.
30:58
Professor Fred Watson: Uh, and part of the problem with that is that
31:00
we've only got one example of life, and
31:02
that's here on Earth. And so we're sort of
31:04
looking for the same kind of chemical
31:05
reactions that formed life here on Earth.
31:08
Earth, uh, to, to form similar life
31:11
elsewhere, but there might be other kinds of
31:12
life that don't need those reactions.
31:15
Andrew Dunkley: Yeah, Ah, it's, um, it's funny
31:18
you mentioned that because it just reminded
31:19
me while we were on our cruise ship, we, we
31:21
played a lot of trivia because, you know,
31:23
that's what you do. And one of the questions
31:26
that came up was, um, um,
31:29
what was. I can't remember the wording, but
31:31
they basically wanted you to explain what the
31:33
Drake equation was. And I think
31:36
only two of us got it out of 200
31:39
people. Uh, I was very proud of
31:42
myself, actually.
31:43
Professor Fred Watson: I'm sure you will be. Yeah. Good on you.
31:46
Andrew Dunkley: Uh, okay, so if you want to find out more
31:48
about the Galactic Habitable Zone, you
31:51
can do that through the universetoday.com
31:53
website. It's a really interesting article
31:55
too. I did manage to read the first
31:57
paragraph.
31:58
Uh, now, um, one thing I wanted
32:01
to mention when you were talking about
32:02
Insight and Mars and Mars not having
32:04
tectonics, I, uh, I meant
32:07
to add this onto the end of that segment, but
32:09
I'll do it now. While we were overseas, uh,
32:11
we went to Iceland and what an
32:14
amazing place Iceland is. Uh, we got to
32:17
walk along a rift valley where the
32:20
Eurasian tectonic plate
32:22
and the American tectonic plate meet. You can
32:25
actually walk along it and the American
32:28
plate is going up and over, the Eurasian
32:30
plate is going down and under, and you can
32:33
walk right on top of that.
32:36
And you're walking along thinking, isn't this
32:38
amazing? And, um,
32:41
then you start seeing the plaques that
32:43
explain, well, this was an earthquake in
32:45
2011, this was an earthquake in 2015.
32:48
And you're thinking, why am I standing here?
32:52
Quite incredible.
32:53
Professor Fred Watson: So the place you were at is a place called
32:55
Thingback. Uh, it's, uh,
32:59
uh, not that far from Reykjavik. Uh,
33:01
Bungs. Uh, it's not plates colliding, it's
33:04
plates dragging apart because you're in the
33:06
middle of. Yeah, so they're
33:08
separating. So you need to be even more
33:10
careful because if they separate a bit faster
33:12
on the day you're walking through it, you're
33:14
going to drop right into the hole.
33:16
Andrew Dunkley: Well, there are a lot of cracks in the ground
33:18
in that part of the. So it does make sense.
33:21
Um, I must not have read the literature
33:24
when they explained what was happening
33:26
exactly, but I thought they said colliding.
33:28
Professor Fred Watson: So it's coming
33:31
apart. It's the Mid Atlantic Ridge. That is
33:33
the only place where the Mid Atlantic Ridge
33:36
is on the surface. And Tingviklijk is
33:39
where it's where it's most obvious. There is
33:41
another place, uh, not very far from there.
33:43
So actually on the Reykjanesput
33:46
Peninsula to the west of,
33:49
uh, Reykjavik. And there, there's a bridge
33:51
across this border. Uh, and you
33:54
can stand on one side of the bridge and
33:56
you're on the Eurasian plate Stand on the
33:58
other. You're on the American complaint. And
33:59
all the locals think it's a great joke
34:01
because you know there are things like this
34:03
all over the island. Basically the island
34:05
splitting in. In pieces because of the. Of
34:08
that separation.
34:09
Andrew Dunkley: But yeah, saw photos of
34:12
people doing that. But we didn't go. We
34:13
didn't go there but we went to. Oh, we went
34:15
to a lot of places in Iceland. But um.
34:19
One of the things we learned about a lot
34:22
in places like Iceland and Greenland and up
34:25
in um, Northern Europe was how
34:27
fast the glaciers are melting. M. And
34:31
shocking. It is very shocking.
34:34
Some of them are um, uh. Ah, losing
34:37
20 metres or 200 metres a year
34:40
I should say, which is staggering. And
34:44
that's lost forever. Um, we can't
34:47
reverse that. So ah, it is rather
34:50
shocking in fact. Uh, we were, I think it was
34:53
when we were in the um, uh,
34:56
Saint Christian Sound, uh, Prince Christian
34:59
Sound, uh, they were saying um,
35:02
see that rock in front of that uh, glacier?
35:04
And we all went yeah. Well it was actually
35:07
covered in ice two years ago. Yeah, that's
35:10
how bad it's getting. And this is just this
35:12
rock in the middle of nowhere and the ice is
35:14
way, way, way back. So yeah,
35:17
pretty shocking stuff. Um,
35:19
that's just about it. Fred Watson, thank you
35:21
so much.
35:23
Professor Fred Watson: It's a pleasure. Andrew, it's great to
35:25
welcome you back and um, I um,
35:28
look forward to continuing the uh, recordings
35:31
at a um, time that
35:34
you don't have to choose between awkward
35:36
times on different sides of the planet. Which
35:38
is what we could do. Heidi and uh, I juggling
35:40
our uh, respective uh, days.
35:43
Andrew Dunkley: It's a bit difficult with those time
35:44
differences. Well, while we were on the ship
35:46
we sold a few and bought a house which in the
35:49
early phases was simple because it was only a
35:51
few hours time difference. But when it got to
35:52
the real crunch of you know, settling it all,
35:56
uh, the time difference was 12 hours. So it
35:58
really got difficult. But uh, it's done now
36:01
and yes, we're in our new place. I should
36:03
show it to you. I've got the, I've got the
36:06
um, the Yankees Red uh, Sox
36:09
baseball game background on. Because I took
36:10
that photo when we went and watched a game in
36:12
New York the other day uh, which was a lot of
36:15
fun and the Red Sox one.
36:16
Professor Fred Watson: Whoops.
36:17
Andrew Dunkley: Um, but um, yeah, I'll put a normal
36:20
background on so you can see the new place
36:22
which pretty much looks the same as the old
36:24
place. But anyway, whatever. Thanks
36:26
Fred Watson. We'll catch you real soon.
36:28
Professor Fred Watson: Sounds good. Thanks Andrew. Take care.
36:31
Andrew Dunkley: Uh, you too. And don't forget, uh, if you
36:33
would like to support the Australasian Dark
36:36
sky alliance and get, uh, those
36:38
signatures on their petition, it's
36:40
australiandarkskyalliance.org
36:43
and, uh, just follow the prompts, uh, for
36:46
Australian signatories only. Australian,
36:49
uh, Australasian
36:50
darkskyalliance.org uh,
36:53
that's it from me. And, oh, I forgot to thank
36:55
Huw in the studio, which
36:58
I quite often do. Uh, from me, Andrew
37:01
Dunkley. Thanks for your company. See you on
37:03
the next episode of Space Nuts. Bye. Bye.
37:06
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