Andrew Dunkley: Hi there. Thanks for joining us again. This
is Space Nuts where we talk astronomy and
space science and all sorts of other things.
And over the last, uh, few
episodes we've been doing some specials
because Fred Watson's away gallivanting
around Scotland playing a lot of golf. Not.
Uh, so we're doing some specials with Jonty
Horner. Uh, and we're doing part
two today of
Astrobiology, a fascinating
part of astronomy and space science. Uh,
one area we get so many questions about. So
stand by as we get into that on this
episode of space nuts. 15
seconds.
Jonti Horner: Guidance is internal. 10,
9, ignition sequence start.
Space nuts. 5, 4, 3, 2. 1. 2,
3, 4, 5, 5, 4, 3, 2, 1.
Space nuts.
Andrew Dunkley: Astronauts report it feels good.
And back with us again is Johnty Horner,
professor of astrophysics at the University
of Southern Queensland. Jonty, hello.
Jonti Horner: Noon. How are you?
Andrew Dunkley: I'm m all right. Can you imagine Fred Watson
playing golf?
Jonti Horner: No, uh, not sure. I mean, growing up in
Yorkshire, the weather wasn't always suited
to it and we were too busy in gravel anyway,
so.
Andrew Dunkley: Yeah, took
a moment. I got that. Yes, yes.
Uh, used to look clean with the tongues.
Jonti Horner: Used to have to get up in the morning at 10
o' clock at night, half an hour before I went
to bed.
Andrew Dunkley: It's just one of the best pieces of comedy
ever.
Jonti Horner: And it's funny because it's true.
Yes.
Andrew Dunkley: Tell the young people that.
Jonti Horner: They won't believe you.
Andrew Dunkley: Oh gosh, it's all flooding back. Uh, we've
got a lot to talk about so we better get
started.
Astrobiology Part two. Um,
a couple of episodes ago we talked
Astrobiology Part one, surprisingly. Um,
let's just do a quick review.
Jonti Horner: Yeah, this is a bit like the bit that really
annoys you at the start of those multi
episode shows where they're previously on
Astrobiology. Um, but
this is basically a case of Jonty talks too
much and so therefore we run out of time. I
mean, we don't need to sugarcoat that. And
it's always a problem when you're talking
about something you love and you're
passionate about that. The time just flies by
and hopefully it's flying by for the
listeners as well, rather than boring them to
tears. But you know, I can't really control
that. In the first episode
we talked a fair bit about the fact that
we've always wondered whether there's life
elsewhere. We talked a bit about the history
in particular things like the ideas of
potentially there being life on Mars that led
to the panic over the War of the Worlds
broadcast and the Fact that In the late
1800s, people were that convinced there
already was known to be life on Mars, that
when a major prize was offered for the
detection of life elsewhere, Mars was
explicitly excluded because that's too easy,
you know. So we've had these ideas for a very
long time, but finding evidence of life
out there is really, really difficult.
We've talked a fair bit about the search for
life within the solar system. You know,
places like looking at Mars, looking at
Europa, all the icy moons. And we talk about
that a lot in the questions that we week by
week as well on the show.
And one thing I've always been really
interested in and passionate about is the
search for life outside the solar system.
Given that we've moved into the exoplanet
era, and we talked a lot about this in the
previous episode as well, we're now in a
position where 30 years ago would have seemed
impossible. Thirty years ago, we'd only just
found the first planet for under the Stars,
and only just answered that question of
whether there are planets at all beyond the
solar system. Now we're at a position where
we are finding places that theoretically, in
the future, we could search to see whether
there's any evidence of life in those
planetary systems. And in all honesty,
despite some of the hyperbolic media
articles that you sometimes see, we haven't
yet found a planet that would really look
like another Earth. But we're getting there,
we're getting closer, we're getting to
planets that are more similar to ours in
size, at more similar distance from their
stars, and we're learning more about them.
And it's very feasible then in the next
decade or so, that we can actually start
looking to see whether there's any evidence
of life on those planets. Now, that's a
little bit separate to looking for signs of
communicative alien technological
life, which is a search for extraterrestrial
intelligence or the search for
extraterrestrial artefacts. There two areas
of science that are fascinating, but they're
more like a search for a needle in a hair
sack, where we don't even know if there is
life elsewhere, never mind intelligent life.
I mean, some people argue whether there's
intelligent life on Earth looking at the news
at the minute, but looking for intelligent
life that has reached certain technological
level to communicate with us is challenging.
It's one of those things if we don't know
what we're looking for, but if we don't look,
we'll never find it. But it still led to some
really fascinating research, and there's a
guy who works with us as part of our Planet
Search Consortium, a guy called Jason Reutt
in the US who spent some of his time actually
thinking about alien megastructures, the
kind of things that feature so heavily in
some advanced science fiction, like Larry
Niven's Ringworld or Dyson Spheres, these
enormous structures that you can imagine a
civilization building. If their technologies
are far above ours, as ours is from the Stone
Age, the idea that you could build something
to harness all the material in your planetary
system m harness all the energy from your
star. Now, many people argue that while
that's theoretically possible, it just
wouldn't be worth the effort. But what
Jason's been looking into is
effectively not could people do
this? But rather if they did, what would it
look like? So it's not really putting any
weight on the probability of
these things existing, but rather saying,
here are things we could imagine that are
within the bounds of physical possibility to
build. Even if they'd be on this
technologically, what would they look like to
our different kinds of telescopes? What would
the signatures be? And, um, that work's
really important because if you don't have an
idea what these peculiar objects would look
like, when you find something unusual, you
won't have that thing to reference again to
cheque it out. So both the search for
extraterrestrial intelligence and the search
for alien artefacts, a kind of
a separate splinter of astrobiology that are
ongoing, that are very precious to us here in
Australia. Of course, we would have lost the
Parks Radio telescope under the Liberal
government in the 2010s in the previous
decade because they wanted to shut it down
and demolish it to save money. And it only
kept going by a large investment
as part of a project to listen
for aliens. So, like 40. I remember
that telescope has been used to search for
extraterrestrial intelligence in the form of
radio signals. And that has kept one of our,
uh, incredible pieces of astronomical
heritage in Australia. And something
incredibly precious and beloved has kept it
going and kept it standing despite the worst
vagaries of politicians and
all those challenges.
Andrew Dunkley: Could you argue that we, uh, have
already created a
megastructure around Earth with the number of
satellites that are currently in orbit and
the so many thousands more that are going to
be put up there in the near future?
Jonti Horner: Certainly feels like that from the inside.
Looking out. I mean, I'm enjoying all the
photos. People are, uh, of Comet 2025
R3 Pan stars at the minute, which behind
both of us are our attempts. We're showing
them off. Andrew's ever so proud from his
attempt last night.
Andrew Dunkley: My first ever comet.
Jonti Horner: Fabulous photos that people are getting, but
I've seen a lot of them getting photobombed
by Starlink satellites. And I've got. I'm
currently, thanks to learning something new
about astrophotography over the last two
days. I'm going back to images I took of
Comet Atlas and Comet um, Church in Chan
Atlas, which were the great comets of 2024
and 2025 to reprocess those
images. But one of my abiding Comet Atlas
was I had this incredible view of it on the
horizon. Took this long series of photos and
every single blooming photo was ruined by a
Starlink satellite because I got a Starlink
train passing overhead that had recently been
launched. All of which went straight through
the middle of the comet and rendered all the
photos unusable on my only really good clear
night. Now, I may be able to solve it, but
that isn't quite at the megastructure stage
yet for me in that I suspect with the
level of technology we've got now or in the
near future, that network of
satellites around the Earth, uh, wouldn't be
something we could detect orbiting a planet
around another star. Right. They're not there
yet, but they're the forebears of something
that could be. Now, being that
they're around a planet rather than a star,
their signature will be different. And given
that we are very skilled now at
broadcasting in one direction rather than
many, and that broadcasting directionally
rather than broadcasting the boy band one
direction should be said, um, broadcasting
in a directional sense. We are moving towards
the point where we're going to stop shrieking
like a screaming infant into the cosmos
anyway. So it may be that we're going to go
radio silent fairly soon, and satellites like
that are going to be part of that journey.
But I think they are an indication of how
quickly these things can happen. You know, if
we were talking a decade ago, we'd have been
talking about a couple of thousand satellites
orbiting Earth. We're now talking about
roughly 50,000. With plants have more than a
million within the next decade, it's getting
quite terrifying, actually. As much from the
atmosphere and climate side of things as
anything else. You know, if we have a million
Starlink satellites in orbit in five years or
10 years time, they have an average lifetime
of five years, which means we'd have more
than 500 per day burning up in the
atmosphere. And that's
a factor of 100, if not more times
material entering the atmosphere on a daily
basis than we get from the background of
space stuff falling in. We'll be running an
experiment in atmospheric science that we've
never run, dumping hundreds of
tonnes of aluminium into the upper atmosphere
every day.
Andrew Dunkley: Yeah, what's the effect going to be? And
that's the $64,000 question, I suppose.
Jonti Horner: But now the interesting thing there, coming
back to the astrobiology, is that might
well create a signature in the Earth's
atmosphere that would be detectable
from observers from around another star.
Because one of the ways that we would look
for biosignatures, at least early
on, will be to look at the light
from a star reaching us whilst a given
planet is transiting between us and the star,
so blocking a bit of that star's light. We
can currently do this with giant planets,
Jupiter sized, and a fraction of the light
from the star passes through the planet's
atmosphere. And you get imprinted on the
stars like the chemical fingerprint of the
constituents of the outer layers of the
atmosphere where the lights pass through in
the form of absorption lines. And um, by
studying them, we can work out some of the
chemical species that are prevalent there and
even learn a bit about the structure of the
atmosphere, the presence of clouds, things
like that. Now when we get to the point where
we've got all those satellites burning up in
our atmosphere, imagining with the kind of
technology that we're looking at developing
within the next decade or so, or maybe a
little bit longer, imagining being on a
nearby star looking at the sun while the
Earth is transiting, you're suddenly
introducing a huge spike of aluminium and
into the absorption in an Earth like planet's
atmosphere. And there is no natural way that
I'm aware of that you could get that.
So that would not only be a sign of something
way going on, it would be a bio signature of
technologically developed life that is not
quite so developed as to have learned that
pollution is bad.
Andrew Dunkley: Maybe that's how we find an
intelligent species, uh, beyond Earth.
They find us first and send us a, you
know, welcome pack.
Jonti Horner: Yes. 10 helpful things you can do to fix your
problems. Stop burning things up in the
atmosphere.
Andrew Dunkley: Um, yes, yeah, they may have already
learned that lesson, but um, yeah, okay,
so that's where we're at so far. Where do we
go from here on the astrobiology
train?
Jonti Horner: Well, where we moved to in the latter part of
the last astrobiology episode
was my argument that
you can't just look at a planet and say it's
at the right temperature in the habitable
zone. Um, we can look There. Whee.
It kind of feels a bit like that when you
read a lot of storeys, that the only
consideration that comes into play is how far
the planet is from its star. And I think
instead, it's fairer to say that there are a
huge variety of factors that can make
one planet more or less suitable for the
development of life and therefore for the
observability of life on planets around other
stars. And therefore, given that the
observations to find life are going to be
overwhelmingly the hardest we've ever had to
carry out, we'll have hundreds, if not
thousands of targets to choose from, but
we'll only be able to look at a tiny handful
of them in detail at first. So we need to be
very careful about where we look. The
proximity of the planet and its host star to
the sun will be important because the closer
the star is to a zombie we get for a given
brightness of star, and also the more widely
separated on the sky a star and planet will
be for a given orbital distance between them.
Closer they are, the more widely separated
they are. And while people listening can't
see this, I'm at the minute pointing fingers
up at the side of my eyes to Andrew and then
moving them towards the camera. Fingers are
the same distance apart, but they get wider
and wider apart on the screen as they get
closer. Yeah. So there are clear reasons that
we will look at stars that are nearer to
us rather than further away. But beyond
that, I think it's really important to
consider all the different things that could
factor in to make a given planet more
suitable or less suitable for the
development of life, and view them as like
sliders on a mixing board in a sound studio,
where you can fine tune things to see which
gets the best sound, which gets the best
score. You can rank your targets and
you can start with the most promising ones,
because with limited resources, you don't
just want to do an unbiased survey, you want
to instead maximise your chances of a
positive result. Now, we're heavily biassed.
We only know of one kind of life and that's
Earth life. So we are very biassed towards
looking for places that could support life
like Earth life, because that's the only kind
of life we do know exists that'll factor into
it as well. But in the previous episode,
towards the end, we talked about the way in
which the location in the galaxy could
potentially influence this, with the caveat,
of course, that, uh, we're going to be
looking at everything nearby. So whilst
that's interesting scientifically, it's not
that relevant. And then we also talked about
the way that the nature of the stars that the
planet orbits can influence things. And uh,
not just from the point of view of is a star,
ah, stable or single, but down to more subtle
things like the fact that stars brighten over
time. So just because a planet is in the
habitable zone now doesn't mean it's been in
that zone for long enough for life to become
well established.
So we talked about all that, where we
finished up though we didn't get to my own
personal favourite parts of the science and
the stuff I'm more directly involved with,
which are the more local influences on the
planet, that is the influence of the
planetary system in which that planet moves,
all the other planets and all the debris
therein, but also the impact of the planet
itself, what it's made of, how it behaves.
And there's a lot of subtlety in that that.
When I prepared with my old mentor, Professor
Barry Jones this review article on this 16
years ago now, we dug into and it
highlighted to me how none of these questions
can be answered from people within a single
research silo at all. You need researchers
from all different disciplines of human
experience, from the sciences, the biological
sciences, physical sciences, geosciences,
chemistry and astronomers all to come
together. You probably also need philosophers
and archaeologists to come into the
discussion to talk about, about how we look
and why we look and what we look for. And
that's particularly true when we start moving
from simple life to life that could talk
back to us. And a very dear friend of mine in
Australia who Fred Watson probably knows very
well as well is Professor Alice Gorman down
at Adelaide, who's a space archaeologist and
has given some of the most astonishing and
mind blowing talks I've ever seen from the
point of view of someone who is trained in
archaeology looking at the record of human
space flight and what we should do to
preserve artefacts like the Apollo landing
site for future generations. Generations how
we should consider that
Andrew Dunkley: I absolutely agree because
it was probably one of the
greatest achievements in human history, if
not the greatest achievement in human
history. I mean inventing the wheel probably
would have been a pretty cool thing too, but
I don't know where that happened or when and
they never would have thought to commemorate
it. But um, it is something that
should, should, you know, when we eventually
have permanent residents on the moon,
at least need to put a cyclone fence around
it just for the time being until we can build
a proper structure to protect
it.
Jonti Horner: Probably a good place to have rabbit proof
fence because that will, that'll do the job.
Andrew Dunkley: Um, yeah, well, you know that rabbits will
ultimately be on the moon. They tend to be
everywhere else.
Jonti Horner: Um, now one of the greatest conference talks
ever witnessed actually was a talk by a list
talking about archaeology. And it was from
the education and biases
point of view. And I know this is already a
bit off topic, but it's a storey I think
really well worth repeating. Alice is an
archaeologist and so she teaches archaeology
students and she gave this talk about how she
took a group of her uh, final year students
to this site in Fairlie Regional New South
Wales for a two day dig. Basically go out
there, dig and come back to me with what you
find and tell me about the storey of the
site. And after two days all these
young students came back and said, look, we
didn't really find much, we found a few
Aboriginal artefacts and that's kind of
interesting, but all we found was a load of
rubbish. We found all these blooming cable
ties and bits of plastic that are polluting
the site. What she then went on to do
was the whole point was that the cable ties
were actually the archaeology that she was
interested in. So she went um, on and um,
said in the talk that this was an old
decommissioned listening station that had
been built I think in like the late 1940s,
post World War II, and operated into maybe
the late 60s, early 70s before being
demolished and removed. But by looking at the
cable ties where they'd been identified had
knowing a little bit about how cable ties and
cable tie technology changed over the years,
you could not only map out exactly where all
the buildings had been and where the wire
runs have been and get the structure of this
long vanished building, you could also
work out which bits were built when. And um,
the whole importance here was partly that
whole thing of one man's trash is another
man's treasure, but it's also how
as a scientist and a researcher, uh,
you will miss things and you'll make mistakes
because of your own personal biases that are
quite often unconscious. And in this case for
these students who've been studying
archaeology, their unconscious bias was that
anything modern is not archaeology. That's
rubbish in the way of good archaeology. And
so they totally miss the point. And it's a
fabulous learning thing. It's why as
scientists we use statistics so much. I know
there's all this stuff about you can show
anything with statistics, damn lies and
statistics, all the rest of it. But
fundamentally the reason that we use
statistics as a tool school is because we as
humans are biassed we've got this incredible
evolutionary ability to see patterns when
they're barely there, but we also have a very
strong ability to see patterns that we expect
to see when those patterns aren't actually
there. And, um, that's certainly true of the
canals on Mars. You know, Giovanni
Schiaparelli saw these canals, these
channels on, um, Mars, which I think the best
explanation is that Mars was really bright.
He had a big telescope and he was actually
seeing the projection of his own capillaries
in his eye, like I'm gonna see tomorrow when
I get my eye test at the opticians and they
do the bright light thing. But all these
other observers with less good eyes and less
good telescopes suddenly started seeing the
canals. And it's this
whole thing of when you're really straining
at the limits of your vision, you see what
you think you're going to see, not what there
actually is. And that's true with our data.
Uh, therefore, you use statistics
to give you a feel for whether what you're
seeing is significant or not, or whether it
exists in the first place. And that's a way
of us combating those biases. Now, that wasn'
in that way to the archaeology students who
thought that cable ties were rubbish, but it
was a fabulous reminder of how we really
need to be aware not only of the explicit
biases, which are the things we choose to do.
If they're doing a survey of people on hair
loss and they say we interviewed men between
18 and 30, that's clearly biassed to
be for men between 18 and 30, not for men of
our age, for example. That's an explicit
bias, it's one that's a conscious choice.
Implicit biases are the sneaky ones, where
you don't realise you're making them. And
that's why I've made it so clear up front
here that we can imagine
all kinds of life. Science fiction does it
wonderfully, but our implicit bias is that,
uh, when we talk about the search for life,
at least in the very short term, we're
actually looking for life like us, not you
and I, but lifelike Earth, uh, life based on
a planet with oceans, living on the surface,
modifying the atmosphere, because that's the
one kind of life we know exists, but also
because that's the one kind of life we could
probably identify with our observations. Life
beneath the ice on Europa is fascinating, but
we can't see it in the solar system. We
wouldn't have a prayer if Europa was found
orbiting another star, because the ice is in
the way life on a surface that modifies an
atmosphere is at least something we
theoretically could detect. So that's making
the implicit explicit.
Andrew Dunkley: Gotcha. All right, we're gonna take a breath,
uh, and get back to Astrobiology Part 2
on Space Nuts.
Let's take a little break from the to tell
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Jonti Horner: 3, 2, 1
space nuts.
Andrew Dunkley: And you're with Andrew Dunkley and Professor
Jonty Horner okay, what next,
Jonty, in this search for
extraterrestrial life?
Jonti Horner: Well, I think we come back to moving away
from the diversions of archaeology and stuff
to the factors that could make a planet more
or less suitable as a target. And like I
said, we talked about the galaxy, we talked
about the stars. To me, as a person who
comes originally from a solar system
background, particularly fascinated with
comets and asteroids and stuff like that,
there are a lot of factors that have been
proposed that relate to
the interaction of planets and the
interaction with the debris that's around
that could render planets more or less
suitable as targets. Now one
example of this is the stability of orbits.
You know, there are a variety of different
models of the solar system's youth, some of
which suggest that there were periods of
chaotic instability where the planets orbits
got stirred up, planets maybe even swapped
orbits. Now this is the kind of thing we can
model. And when we discover planetary
systems, we can take the planets that we
think are there and put them into computer
software to run their orbits forward and back
in time to see how they behave. And that's
actually part of my day to day work. That's
the technology I use and lots of tools I've
used in the past to kill planetary systems
that people thought were there because I run
simulations and showed they're simply not
stable on very short timescales.
But on longer time scales, these kind of
perturbations can have a significant impact
on the orbits of planets. You can get
significant shifts over time. You can get
encounters and stirring up, which means
sometimes that a planet will be on an orbit
now that is not the orbit it's occupied in
the past. And uh, those are things that we
could probably pull out, tease out from the
simulation kind of work that I do. And
obviously a planet that is now in the
habitable zone, um, but that was previously
well outside it would not be a good place to
look. Even though it looks good now, it's not
great. It's like, I guess, you know, you've
got two petri dishes in front of you that you
could look at for life, but you can tell that
one of them's been absolutely melted in a
fire. It's at room temperature now, but that
doesn't mean it always has been that same
kind of idea. So that on a coarse scale has
an effect. But there's a subtler version of
that that I've done a little bit of work on
in the past. And I've got a PhD student
working with me at the moment minute, who's
going to look into this a lot more. A
wonderful student called Amber Tilly. It's
the idea of the Milankovitch cycles.
Now, on Earth, we
look at climate change in the short term as
being a big problem because it's a very rapid
change that is being caused by human action.
But on much longer timescales, the climate of
Earth is periodically variable. We've had ice
ages and interglacial periods for the last 2
or 3 million years, which are the direct
result of the subtle nudges and tweaks on
the, uh, Earth from all the other objects in
the solar system, primarily the other
planets, and not mainly Jupiter to be honest.
But most of the planets contribute. These are
called the Milankovitch cycles. They have a
number of effects. Firstly, the Earth on its
axis precesses. It wobbles with a period of
about 23,000 years. So our polar
axis, which is tilted by currently 23 and a
half degrees to the plane of our orbit,
wobbles around like a kid's wobbly spinning
toy coming to a stop. It precesses, wobbles
around a bit like the thing in Inception
about to fall over. You see this procession?
That's a procession of the equinoxes. That's
why your horoscopes are wrong. While it's one
of the many reasons that your horoscopes are
wrong, but it's particularly why your
horoscopes are out by one particular one
full calendar month. Because the
horoscopes are based on where the sun is, was
in the sky at that date 2,000 years ago.
And, um, the axis of the Earth has wobbled
round, so it's now one constellation round.
So when the sun is in Aries, according to
your horoscope, it's actually now in Pisces,
all because of the wobble. That wobble takes
23,000 years to complete. That means that
the direction that the Earth is pointing
changes over time. Essentially. Added
to that, you've got a very slight wobble up
and down where the tilt fire axis, which is
currently 23 and a half degrees, changes from
about 22 to, to 24 degrees, rocking back and
forward. So that causes the size of the
Arctic and Antarctic circles to grow and
shrink very slightly. On um, top of all that,
you've then got the Earth's orbit around the
sun flexing and tilting. Its shape
becomes more circular and more elongated,
more eccentric. With a longer period period,
I think about 100,000 years, something like
that, our orbit, compared to the orbits of
Jupiter and Saturn, tilts a little bit up and
down the inclination changes, which adds to
the change of the tilt in our spin axis a
little bit. We also have the Earth's orbit
precessing around in just the same way our
poles do, and that's a little bit harder to
visualise. But what that means is that the
direction, if you drew a line from the sun
through the Earth and out into space at, ah,
the point the Earth was at perihelion closest
to the sun, that direction will
gradually move round over time, doing a full
lap with a period of several tens of
thousands of years. So our perihelion
possession processes as well, all of the,
that combined means that, uh,
on average the amount of energy reaching the
Earth's polar regions, averaged over a given
year, varies with type. Sometimes the
poles get a bit more energy and the ice
sheets retreat. Sometimes they get a bit less
energy and the ice sheets come back towards
the equator again. Now, there's a lot of
complex feedback from the Earth because ice
is more reflective than water or land. So
when ice is growing, it has a tendency to
keep growing, and when it's shrinking, that
has a tendency to run away as well. So you've
got all these different feedbacks. But what
that means is that on the Earth we've got
these periodic variations in the
amount of energy at the poles which lead to
periodic glaciations and interglacial
periods. That's the Milankovitch cycles.
It means that on timescales of tens of
thousands of years, our climate is relatively
changeable. What would
happen if the planets were on different
orbits or if you were in a
planetary system with a totally different
architecture? The result would be very
different Milankovitch cycles. You'd have
different periods and you'd also have
different amplitudes. You could imagine
scenarios where instead of our Earth rocking
a little bit from 22 to 24 degrees and back
with its polar axis, it could be like Mars,
whose spin axis varies chaotically, can even
tip over on its side. You could have systems
where there's barely any change whatsoever.
You've got this full gap. Now the beauty is,
again, we've got the tools to test this.
We can run the kind of computational
simulations that I've spent my career doing
and, uh, model the orbits of a planet over
time under the influence of all the other
planets. And I did a lot of simulations of
this between 2012 and 2020. I
kept coming back to the idea, but never got
around to publishing it until we got to 2020,
where I published it with, um, Stephen Cain
from University of California, Riverside. Pam
Vervoort, who was his PhD student at the
time, a couple of other people, people where
we said, what is the influence of Jupiter on
our Milankovitch cycles? What would happen if
you move Jupiter closer to the sun or further
away? If you made Jupiter's
orbit more eccentric or less eccentric, how
would that change the period and, um,
amplitude of the Earth's? Milankovic cycles
did the test. And in many cases, moving
Jupiter destroyed the solar system, which
meant the Earth wouldn't be here, which was
kind of fun, but not very helpful. But for
the versions of the solar system where the,
the Earth was not removed, we got to see
the range, the variety of Milankovitch cycles
we would have from moving Jupiter in a bit
closer or moving it a bit further away. And
for those really interested, we moved Jupiter
in as far as 3 Au from the sun, out as far as
7 Au from the sun, where 5 Au is about where
it is at the minute, 5.2. What we
found, which is quite surprising, is that the
Earth's, uh, Milankovitch cycles are neither
unusually big or unusually small. They're
somewhere in the middle. Middle. Which is a
bit of an argument against a hypothesis
called the Rare Earth hypothesis.
This idea has been around for about 20, 25,
30 years, and I've never really liked it.
It's the idea that life on Earth is such a
remarkable, incredible fluke
that we will never find life elsewhere. And
the authors put forward all these
peculiarities about the Earth, uh, and argue
that without them we would not be here.
And it's a bit of a philosophical thing, but
I think it's very dangerous to look at
somewhere that has life and say, this place
has all these unusual things and they are
therefore required for life because we've
never found life elsewhere. A good example is
the presence of a large moon. And we'll talk
about this a bit more later on. We have life
on Earth and we have a big moon, so it's
natural to think you need a big moon to have
life. But we won't know that until we find
life elsewhere. But that led to this argument
of rare Earth life will be uncommon in the
universe. If rare Earth were true,
then when you look at something like the
Milankovitch cycles, you would expect our
Earth to be unusual in some way,
to have conditions that favour life over your
typical system. And we simply don't find that
our Milankovitch cycles are fairly run of the
mill. They're not big, they're not small,
they're not fast. They're not slow, they're
somewhere in the middle. Now,
um, sorry, Pam went with that. Pam lava vault
was.
She then took the output of that and run it
into climate modelling software, which was
fabulous. And she published that work, work
with us in 2022, where
she was able to link the Milankovitch cycles.
We predicted if you moved Jupiter around
with the amplitude and frequency of the
ice ages, we'd get. And it was really
interesting because it turned out that when
you factor in some of the feedback mechanisms
that are in climate modelling, you actually
could change the Earth's Milkovitch cycles a
little bit and get very drastically different
ice ages, much more frequent and shallower,
or much less frequent and deeper just by
small changes. Now, now, it's all
fascinating just from the solar system point
of view, but what we're really doing is we're
putting down tools that when we find
planets that could be suitable, we can do
these same tests. We can look at them and
say, we're thinking that you might be a
target for life. Let's see what your
Melankovic cycles are like. Let's see how
stable your climate is. And if we find
somewhere that flops between snowball Earth
and a hothouse every 10 years, or that has
incredibly long snowball Earth periods
followed by short periods of temperate
climate climate, even though everything else
looks good, that's probably not as, uh,
suitable for life as somewhere that is
temperate all the time. So we can use that as
a bit of a filter. And that's where the new
PhD student we've got, Amber Tilly, comes in.
Amber's, um, going to be doing the same kind
of work, moving it forward, where she's going
to be looking at a whole slew of different
parameters to see how the
Milankovitch cycles change as you vary
things. She's both going to look at what
would happen if the Earth was a bit more
massive or less massive. How would that
change things? Because of the feedback, you
make Earth more massive, it interacts,
interacts more with other things, stirs them
up, you get a feedback there. She's also
going to look, working with colleagues of
ours overseas, at, uh, models of planet
formation that form planetary systems similar
to the solar system as theoretical
data, and say, what would the Milankovitch
cycles be like in this hypothetical system?
So it's not just a purely hypothetical
question, it's something we can actually dig
into and, um, we can test. And I think
that's fundamental to science. It's no good
just arguing something you want to be able to
Test. Test it.
Andrew Dunkley: Yeah. I suppose what you're suggesting is
that by mucking around with
what we know and making slight alterations,
it gives you an idea of what to look
for going forward in identifying
potential targets.
Jonti Horner: Absolutely. And it's good because one of the
reasons that you'd want to use the Earth is
because we've got a ground truth. You can run
the Earth with the current solar system
parameters and put them into a climate model.
And you should get what we see so we can
ground truth it, which is really, really
important. And, um, that is, I think, one of
the main, most obvious ways where even in a
dynamically stable system, a system that
isn't tearing itself apart, interaction
between planets could have a significant
impact on habitability. And we want to look
into it. It's really, really fascinating.
Andrew Dunkley: Indeed it is. All right, um, we
are talking astrobiology on this
special episode of Space Nuts with Professor
Jonty Horner.
Back in.
Okay, we checked all four systems and
Jonti Horner: being with a go, space nets.
Andrew Dunkley: Jody, I thought we might just start off
this, uh, final segment with a
question from the audience. Uh, it's funny
because this question's come in before any of
these astrobiology episodes have
been released. And yet it's
exactly what we've been talking about. This
comes from Chris.
Jonti Horner: Hi, um, I'm Chris from Axmouth in the uk.
I'd, uh, just like to ask, um, given that
interstellar travel to distance solar systems
is likely to remain impractical for humans,
um, do you think a more realistic long term
strategy would be to
Andrew Dunkley: seed the galaxy with the basic building
blocks of life? Uh, for example,
uh, sending autonomous probes carrying
microbes or prebiotic material that could
Jonti Horner: eventually take hold on suitable planets,
even
Andrew Dunkley: if that process takes thousands or millions
of years.
Jonti Horner: Thanks.
Andrew Dunkley: There's a, uh, thought from Chris. So
he's probably suggesting, you know, could we
seed other planets? Uh, would that be
the way to go? Uh, and autonomous,
uh, vehicles. I think last
time we talked about this a couple of
episodes ago, you, you suggested it's,
it's beyond us to actually
send a human mission to another world
to investigate life. But we could
go the way of autonomous vehicles.
Uh, but for the major
distances, like the impossible distances, uh,
we would have to come up with equipment in
the future that could do it from a
stable environment nearby. Um,
I don't know how you want to tackle that
question.
Jonti Horner: There's a fair bit to it, and I mean, it
reminds me of the wonderful Bobbyverse books
that I've quite enjoyed. You know, um, the
Storey of the Self Intelligent Von Neumann
probes, which are, uh, easy listening and
work very well as audiobooks.
It's a challenging one. So we could
do this. It would be feasible.
The question would become whether it's
ethical and right. Yes, and that's a really
challenging one. Now, there is something that
costs research missions
a vast amount of money called planetary
protection. And it's the idea that if we're
sending a spacecraft that has a possibility
of touching down on a place where we are
currently interested in looking for life,
where there could be life, such as Mars, such
as Europa, uh, Ganymede, Titan, around
Saturn. We don't want to take life with
us because you don't want to find life on
Mars only to discover it's what you took with
you. And also we don't want to pollute or
contaminate those environments. So there's a
huge amount of effort and expense, goes into
extreme sterilisation of spacecraft to kind
of prevent exactly the hypothesis being
discussed here. At the same time,
that idea of populating the galaxy with
simple life that could one day grow
to resemblers or something else has
cropped a few times in science fiction. I
believe that was how Star Trek got
around the fact that all of their humanoid
species looked like people with makeup on.
Um, which of course is a budgetary issue and
a special effects issue. But they had an
episode where people found the founders,
which were an alien, ancient alien humanoid
race at seed of the galaxy. And billions of
years later all these different planets had
grown humanoids that looked like them and.
Oh, well, convenient job done. Stop asking us
that question now, please. Effectively it
is something we could do and the timescales
would be immense. It's also something that,
in all honesty, has already happened. There's
this idea called panspermia, which is the
idea that life could be transferred through
space from planet to planet, carried by
debris from impacts and talking. Thirty or
40 years ago, it was viewed as very much
crank science, not feasible. But every
experiment that people have ever done
suggests that it could work. And I've even
had a PhD student just submit his thesis,
Greg Davis, who has been looking at this
from the point of view of the viability of
bacteria transferred from Earth to Mars or
Mars to Earth in the radiation environment in
the solar system. And it seems to work.
Now, to me, the fact that biological, uh,
material from Earth will have rained down on
Mars and Europa and Ganymede and everywhere
else for the last 4 billion years
probably means that we're being a bit over
cautious with our planet protection efforts
because we're trying not to take something
there when it's already there, it's already
been delivered. The other thing is that
anything we take with us to a place that has
an incredibly, incredibly different
environment, if there is life there already,
that life should hugely outcompete anything
we take with us because it's better adapted
for that environment. And that would be one
of the challenges with this, is sending stuff
out. It'd have to be lucky to get exactly the
right environment to grow. But with the
amount of real estate we've got out there it
could happen. People have even in some more
extreme sci fi suggested kind of
this type approach as a way to
begin terraforming planets ahead of human
arrival. This idea that you could send
generation ships which have to go
slowly because they're really big and carry a
lot of people. But you could send faster
moving, smaller things first to start
working on the biosphere of a planet to make
it so that when we get there that planet is a
suitable home. So there's a lot of ways it
could be taken. Taken. I think to do it
in the near future in an official organised
way would require a significant shift in
global morality in the way we think about
other habitats. If we found that
Mars absolutely has no life and
possibly that it never had life, which I
think is probably unlikely, then I could see
people arguing then for terraforming.
Similarly people have argued about, I think
Carl Sagan suggested this, creating
engineering bacteria that could float in the
clouds of Venus and um, precipitate out the
carbon to eventually make Venus a more
habitable planet on long timescales. The idea
of terraforming these worlds is real. But I
think it would require either a state
to go its own way because as we know, once
things are up in space, ain't nobody going to
stop you. Uh, as was the case with the
Israeli spacecraft that spattered tamigards,
um, water bears over the moon to show that
they could, which was so dumb it's untrue.
Um, yep, there are water bears on the moon,
probably desiccated and dried up, but they
can come back from that, we know that. Um, so
you could have a nation just decide to do it
anyway. At the end of the day, if a
random government decided to send a
spacecraft to Mars within a capsule inside
laden with biological bacterial life
to spurt out on the surface, no way we could
stop them. And once it's done, it's done. Um,
but I think the block to the question is not
actually a scientific one, it's an ethical
one and it's about how we, we choose to
interact with the galaxy going forward and
particularly our local environment. That'll
determine at what stage we do that, if we
ever do so. It's a really good question.
Andrew Dunkley: It is. Uh, thanks for the uh, question,
Chris. Uh, Chris, you might be interested to
look up the BBC radio science
fiction comedy called Paradise Lost in Space.
Have you heard of this one? It's so funny.
It's about two blokes who um, get ejected
from a spaceship by an exploding toilet or
something and they end up on a world that's
occupied by uh, an insect, intelligent but
very naive species. So
basically what they do is they try to
pass on their Earth knowledge and
intelligence to these, these people
and ultimately destroy the planet.
Jonti Horner: It's a perfect reflection.
Andrew Dunkley: Brilliant.
Jonti Horner: It's very funny. Yes.
Andrew Dunkley: Yeah, it's funny stuff. So yeah, it's called
um, Paradise Lost in Space. I
only remember it because we ran it as a
series on the ABC some years ago and, and got
a uh, fabulous response. And I always,
I sat there in the studio while we were
running it and I just cackled as to. Because
I could imagine that's what we might do.
Not on purpose, but um. Yeah. And it's what
you say, it's the ethics of sending
our ah, junk to other places that are already
occupied. Yeah. Um,
we're running out of time I suppose. But um,
how do you want to wind this up? Uh, how do
you.
There's so much to talk about, it could go on
for hours.
Jonti Horner: I know more to talk about. I think I'll carry
on until you kind of get the hook and pull me
off about the different things that influence
planet's habitability. Because we've talked
about Milankovitch cycles. We also have as
the influence of the planetary system impact
us just as the dinosaurs, they had a very bad
day. And there has historically been this
idea that ties into the rare Earth thing that
Jupiter is our friend and saviour and without
Jupiter we'd be hit by asteroids more often
and we wouldn't be here. And therefore life
is rare in the universe. Um, idea
basically that Jupiter is our bestest friend
and it's honestly a lot of cobs wallop and
it's both one of my favourite bits of
research I ever did. And probably one of the
biggest bugbears of my career is uh, I
did work again with Barry Jones starting 20
years ago for a few years that resulted in a
series of pep called Jupiter Friend or Foe.
And we did simulations to test the role of
Jupiter in protecting us from impacts or not.
And it turns out that Jupiter is not shielded
all if you took Jupiter away, Earth would be
hit less often. If however you
replace Jupiter with a planet, the mass of
Saturn, Earth would be hit more often than we
are today. And with Jupiter, the mass it
currently is, we'd be hit more than if it
wasn't there, but less than if we put Saturn
there. All down to the subtleties of how
gravity all works. And so basically if you
replace Jupiter with Saturn, it's like the
anti Goldilocks case where you've lesser
porridge with strychnine. But the reality is
that Jupiter's role is complicated,
best illustrated by Comet Lexell in
1770, which I always love. Comet Lexell was
a great comet. It was very bright in our sky.
Discovered by Charles Messier I think 1st of
June 1770. Quickly got as
bright as the brightest stars in the sky, but
looked unusual. It was very big and fuzzy and
it moved unusually rapidly across the sky at
its quickest, covering 42 degrees in a single
hour. When they worked out the orbit of this
thing, they found a that it had come very
close to the Earth. It passed within 2
million kilometres, which is the close
closest approach of a large comet in
historical times. It also was moving
on an orbit that was just less than six years
in period. Big bright comet going around
every six years. Why on Earth have we not
seen it before? Why have we not seen it in
1764 or 1758? Well,
when they worked out the orbit and run it
back in time and this was hard at the time
because they didn't have mechanical
computers, they had human computers who sat
there and did calculations with abakai and
slide rules and all the rest of it. They
found that three years before it nearly hit
the Earth it was very close to Jupiter. In
fact, prior to that it had been moving on an
orbit that came nowhere near the Earth, that
was probably hundreds or thousands of years
in period and it was flying in to come
nowhere near the inner solar system. When it
had this close encounter with Jupiter that
trapped it and threw it at the Earth and
captured it onto the six year long Jupiter
family comet orbit. So Jupiter took something
that was coming nowhere near us and threw it
out at us. We don't see the comet
anymore because 2 times 6 years is
12 years and Jupiter takes 12 years to go
around the sun. So the comet did two laps in
the time Jupiter took to take one. And when
the comet got back out there again 12 years
after the first encounter, Jupiter was there,
grabbed hold of it and threw it away again,
never to return. So in just this 12 year
period, Jupiter threw something at us and
then cleaned up after itself. And whether
Jupiter's more of a shield or more of a
threat is down to the balance of those two
effects. Um, and what we found in our
simulations is, to be honest with Jupiter, we
get hit more than we would do if it wasn't
there. That takes away the idea
that it's our protector. It takes away the
idea that you need a shield to shield a
planet to prevent life from being wiped out.
Another nail in the coffin of rare Earth. And
it bugs me a bit that so many documentaries
still trot out this trite idea that Jupiter
shields us from impacts. And it's wonderful
because I disprove that 20 years ago. It's
much more complicated. But even that idea
gets complicated because obviously we don't
want to have the Earth punishingly, uh,
pummelling because we'd be wiped out. But
where the Earth formed in the solar system,
it probably formed dry. We formed interior to
the location of the ice line. So there wasn't
any available solid water, the water was all
gas. So how the Earth got its water was a
long, outstanding problem, exacerbated by the
fact that towards the end of our planet's
formation, we got smashed into by an object
the size of Mars, which stripped off a lot of
the Earth's core and mantle and would have
desiccated our planet because m water would
have been in the. Or a mantle, in the crust
and mantle. Sorry, up near the surface. Yeah.
So where did the water come from? And Earth
is actually a remarkably dry planet, um,
particularly at the moment in Queensland. The
idea is down here. Yeah, the idea is that our
water, at least in significant part, was
delivered from further out by impacts in what
is often described as a late veneer.
That's really interesting air because that's
a stochastic process, it's random, it's
driven by the orbits of the planets and the
cleanup phase of solar system formation.
So different planetary systems will give
planets with different amounts of water. But
it's also indicating that you actually don't
want too much shielding, you need
impacts. Because if the Earth had never had
the impacts, we'd have never got enough water
for life to develop and thrive. On top of
that, if the Earth didn't have enough
impacts, the dinosaurs would never have been
wiped out. And maybe you and I will be
reptiles or maybe we'll be here, you know,
so there's a whole aspect of that. Now,
again, those Simulations I did, we can
rerun through the planetary systems, we can
find the debris belts in those systems, we
can find the planets so we can model their
impact rates. And I'd argue that we want to
look somewhere that doesn't have too many
impacts, but also doesn't have too few,
because each of those could pose problems.
That is a really big part of the storey
and it feeds into the last point, really,
which is the planet itself and a little bit
tied to the large moon. So our Earth, it has
been suggested again by the rare Earth crowd,
that the large moon we have stabilises our
atmosphere axis and has kept the Earth
habitable. So therefore you need a giant
satellite. But simulations by Dave
Waltham, who's a guy I know very well in the
uk, looked into this and what he found was
that you could take the Moon away and, uh,
the Earth's axis would still be fairly
stable. It still wobbled between about 22 and
24 degrees, maybe a little bit more. But
quirkily, if you made the moon just 12
kilometres larger in diameter,
it would make the Earth's axis unstable and
chaotic. So if the moon was only slightly
larger, we would not be here. The
other reason that a large moon has been
suggested is that it drives bigger tides. And
one of the common arguments for how life
first got going and, um, for how life moved
out of the oceans in both cases is to do with
the large tidal intertidal areas that we
have, where at low tide it's dry and at high
tide it's underwater. And the idea is that
without the moon those areas would be smaller
and life would have had less chance to get
going. I don't really buy that, because if
you took the moon away, the tides of sun
raises would still be half the size, so you'd
still have substantial tides. But these are
all the kind of questions people ask before
you get to the planet itself. And the planet
itself is where my head really hurt. Now, I'm
not a geophysicist at
all, so a lot of this was new to me. Now, we
talked a little bit about the hydration. You
could imagine anything from desert worlds to
worlds with hundreds of kilometres depth of
ocean. Now, if the ocean's too deep,
the planet is probably habitable, but not
detectably habitable because the life will be
at the bottom of the ocean where the
nutrients have been introduced by volc. But
an ocean deeper than a few tens of kilometres
is thought to become stagnant. And so it
doesn't mix things up to the surface, so you
don't want to look at water worlds that are
ocean for hundreds or thousands of kilometres
depth, but equally you want to have some mix
of ocean and continent to allow all the
carbon cycles and weathering to happen, to
allow life to engage with the atmosphere. So
that's a bit of a sweet spot there. But what
I didn't realise was how critical
water has been been to the
maintenance of our atmosphere and um, thereby
our climate against the vagaries of the solar
wind and against the vagaries of plate
tectonics. Now compare the Earth and Mars
and the Earth is warm and wet. We've got a
lovely thick atmosphere and we've not really
lost much of our atmosphere. We've got the
ozone layer which protects us to some degree
from UV radiation. We've got a temperature
inversion about 10 kilometres up in the
atmosphere that traps water below that level.
If water gets above that level, it freezes
and falls back down. So the water can't get
high enough to be ionised and split hydrogen
and helium and lost. Mars doesn't have that.
Mars doesn't have much of a magnetic field
whereas the Earth does. And the magnetic
field protects the atmosphere from being
stripped away from the outside in. Mars
doesn't have plate tectonics, but we do. And
um, plate tectonics prevents the atmosphere
from being precipitated out onto the surface
through chemistry and trapped there because
plate tectonics recycles the crust. So
anything that chemically gets weathered onto
Earth's surface gets put back into the
atmosphere through volcanic volcanoes. So
Mars and Earth probably started out looking
very similar and are now very, very
different. And so the nature of the planet
itself is going to be a real important
factor. And plate tectonics looks like it's
going to be fairly key. Plate tectonics is a
mechanism by which you stop the atmosphere
getting precipitated out and frozen in onto
the surface, which is a big part of what's
happened m on Mars because of that recycling
effect. But it also turns out that plate
tectonics is key in ensuring the
magnetic field is retained. And um, this is a
bit that really hurt my head because I'm
like, I'm not a geophysicist. Seems that on
the Earth if the Earth didn't have plate
tectonics, we'd probably have lost most of
our magnetic field like Mars and like Venus.
What's happening is that the magnetic field
is driven by convection currents in the outer
mantle. Like when you see water boiling in a
kettle overturn, um, motion of mollie and
metal Rising and falling. That
convection can only happen if you've got a
big temperature difference between the bottom
and the top of the outer core. Sorry.
In order to get that temperature difference,
you need to be able to very effectively cool
the top of the outer core because otherwise
it would warm up so much convection would
stop because you don't have enough
temperature difference. The way the outer
core is cooled is by convection in the
mantle. That takes the heat away from the top
of the outer core and brings it to the
surface. We've got these huge convection
cells in the mantle that transfer heat very
quickly. Allowing cool the outer core's top
to get this big temperature difference allows
a motion that drives a magnetic field.
That motion is also what drives plate
tectonics. Now, the quirky thing that came
out of all of this when I was reading about
it is that, uh, if you run simulations of the
motion of the Earth's mantle and the crust
and the Earth is dry, the Earth is too small
to sustain plate tectonics because the mantle
is too stiff. If you have water
and you mix water into the mantle, you
lubricate, lubricate it. You allow convection
in the mantle, which allows plate tectonics,
which allows you to recycle the surface. But
that plate tectonics also allows you to cool
the outer core to maintain the magnetic
field, allowing you to have that magnetic
shield that protects your planet from the
atmosphere being whittled away from the
outside in by the solar wind. It
seems that the storey of plate tectonics, the
Earth's magnetic field and, um, the
atmosphere being retained, is all tied
together by water. Which brings us back to
that delivery question. If the Earth had not
got that veneer of water, would plate
tectonics still happen? The infinite
suggestion, and this was fabulous work by
people working with the great Craig o',
Neill, a great Australian scientist who does
earthquakes and, um, plate tectonics
modelling in an astrobiology sense that
says the Earth's plate tectonics are
really hard to get started. If you run models
of the Earth without plate tectonics with the
young Earth, with how hot it was, plate
tectonics don't just happen. However, if
you introduce impacts from big asteroids,
like the things you got at the end of planet
formation, those can dump enough energy
in terms of a downward pulse to push magma
up somewhere else to trigger a convection
cell that then becomes self sustaining. So
it's quite possible that the same impact
regime that led to the delivery of water,
that led in the extreme case to the formation
of the moon, also triggered plate
Tectonics. And by triggering plate tectonics
and delivering water to the mantle allowed
the Earth to become the planet it is today to
allow life to thrive. Now there's far, far
more that you could look into about the
planets themselves. I'm not like, say, a
geophysicist, but the interplay of these
things is fascinating and it's a real
reminder of that multidisciplinary thing. You
can't do it all if you're just an astronomy.
You need everybody from all different
disciplines to come together so we can figure
out what factors are and, um, aren't
important. So that when we find another
thousand, another ten thousand, another
hundred thousand planets, we can pick the
best targets to search for life upon them.
And that was a motivation and it just blew my
mind when I got to that final part. Just how
much complexity there is in the
interplay between the atmosphere, the
climate, the plate tectonics, the oceans
that are so, uh, variable and so chaotic.
What does that mean? How can we learn from
that? Well, that's what we learn when we look
at planets around other stars. But at least
this gives us a bit of a starting point
point, I think.
Andrew Dunkley: Yeah, yeah, I see what you're saying. So it's
like the popular press saying, oh, we found a
rocky planet in the Goldilocks zone and it
probably has water, so, you know, it's got to
have life. Uh, there's so much more than
that. Like, yeah, it's um.
Jonti Horner: Even they probably have water is a leap
because like, yeah, if we'd not had
water added after the moon forming impact,
the Earth would be a desert
Andrew Dunkley: and we wouldn't probably exist at all.
Jonti Horner: Absolutely, yeah.
Andrew Dunkley: Fascinating stuff, Jonty. We'll leave it
there. But, um, it's just such a
fascinating topic. But
what goes into, uh, the future
identification of potential targets is
so much more than most people would have
considered. So thank you very much, really
appreciate it.
Jonti Horner: It's an absolute pleasure and thanks for
letting me rant on my topics of choice for a
change. Like I said, it would be helpful. I'm
sure your readers will.
Readers, listeners will give feedback on
this, but I know we've done something
different. I really do. I am aware
of the fact that these are not your typical
episodes and that may be different for
people. So I appreciate the opportunity to do
this, but if people have enjoyed it or
didn't, it'd probably be worth letting Andrew
and Fred Watson know once I'm gone. Um, won't
hurt my feelings. Don't worry about it
because if it's Something you've enjoyed.
There's possibilities to do things like this
again in future if it isn't. We tried it and
it didn't work and that's entirely fine. Fine
too. So hopefully it was fun, hopefully it
was educational and I won't be too hurt, uh,
if nobody enjoyed it.
Andrew Dunkley: I'm pretty sure they did. Jonty, and we
really appreciate your time and uh, we've,
we've got one more episode to do with you.
Uh, it's a Q and A episode and we, we're
talking about, we haven't nailed it down yet,
but we're talking about doing a, an
astrophotography special.
Jonti Horner: Yeah.
Andrew Dunkley: Because we do get a lot of questions about
astrophotography so, uh, that, that'd be
worth getting into as well.
Jonti Horner: Yeah. I've got a couple of good friends who
uh, are award winning astrophotographers who
we're going to try and rope into that. So
watch this space is what I'd say. Yes.
Andrew Dunkley: Fingers crossed we can nail that one down.
Jonty, thanks so much. We'll see you real
soon.
Jonti Horner: Pleasure. Thank you for having me.
Andrew Dunkley: Johnty Horner, professor of Astrophysics at
the University of Southern Queensland.
And if you've got time, jump on our website
and have a look around. Uh, maybe send your
comments and thoughts, uh, to us via the
Ask me anything button at the top. It's
labelled ama. And while you're there, cheque
out the Astronomy AstroDailyPod feed. Maybe
sign up for your daily dose of astronomy
news. Um, maybe you'd like to become a
subscriber. You can do that. Visit, uh, the
shop. Lots of goodies in our shop and plenty
more. So cheque it out and thanks to Huw
in the studio as always, because
he does something which we one day might
find out about. And from me, Andrew Dunkley,
thanks for your company. We'll see you on the
next episode of Space Nuts. Bye Bye.
Space Nuts.
You've been listening to the Space Nuts
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Andrew Dunkley: Um, this has been another quality podcast
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Jonti Horner: Um,