Join Andrew Dunkley and Professor Jonti Horner in this enlightening episode of Space Nuts, where they explore the cosmos' latest discoveries and debunk popular misconceptions. From the astonishing natural megastructure known as Quipu to the reality behind potentially habitable exoplanets, and the implications of SpaceX satellites re-entering Earth's atmosphere, this episode is packed with fascinating insights that will expand your understanding of our universe.
Episode Highlights:
- The Discovery of Quipu: Andrew and Jonti discuss the recently discovered megastructure, Quipu, which is a colossal natural formation in the universe. They delve into its size, significance, and the implications it has for our understanding of cosmic structures.
- Exoplanet Misconceptions: Jonti shares his frustrations regarding the overselling of exoplanet discoveries and the potential for life. They dissect the media's portrayal of newly found planets and emphasize the complexities involved in determining habitability.
- Asteroid 2024 YR4 Update: The duo provides an update on the asteroid's trajectory and the fluctuating odds of it impacting Earth. They explain how ongoing observations refine our understanding of its orbit and potential risks.
- SpaceX Satellites and Atmospheric Concerns: Andrew and Jonti examine the increasing number of SpaceX satellites re-entering the atmosphere and the environmental implications of this phenomenon. They discuss the balance between technological advancements and potential ecological impacts.
For more Space Nuts, including our continually updating newsfeed and to listen to all our episodes, visit our website. Follow us on social media at SpaceNutsPod on Facebook, X, YouTube Music, Tumblr, Instagram, and TikTok. We love engaging with our community, so be sure to drop us a message or comment on your favorite platform.
If you'd like to help support Space Nuts and join our growing family of insiders for commercial-free episodes and more, visit spacenutspodcast.com/about
Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
00:00 - Introduction to the episode and topics
02:15 - Discussion on the discovery of Quipu and its implications
10:30 - Debunking myths around exoplanets and habitability
18:00 - Update on asteroid 2024 YR4 and its potential impact
26:45 - The environmental impact of SpaceX satellites re-entering
30:00 - Closing thoughts and listener engagement
✍️ Episode References
Quipu Discovery Article
https://www.astronomy.com/news
Exoplanet Research
https://www.nasa.gov/exoplanets
SpaceX Satellite Updates
https://www.spacex.com/launches/
Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support.
00:00:00 --> 00:00:01 Andrew Dunkley: Hi there, thanks for joining us. This is
00:00:01 --> 00:00:03 Space Nuts. Andrew Dunkley here. Good to have
00:00:03 --> 00:00:06 your company. And on this episode we
00:00:06 --> 00:00:09 have a lot to talk
00:00:09 --> 00:00:09 about.
00:00:09 --> 00:00:12 The uh, first thing will be a megastructure
00:00:12 --> 00:00:15 of epic proportions discovered in the
00:00:15 --> 00:00:17 universe. Now this is not a uh, uh, something
00:00:17 --> 00:00:20 that was manufactured by some incredible
00:00:20 --> 00:00:22 race because uh, we have talked about
00:00:23 --> 00:00:24 megastructures in the past. Now this is
00:00:24 --> 00:00:27 natural and it's called Quipu.
00:00:28 --> 00:00:30 What's that mean? We'll tell you soon. Um,
00:00:30 --> 00:00:33 this is uh, one of um, the biggest bugbears
00:00:33 --> 00:00:36 that Jonti has to deal with the overselling
00:00:36 --> 00:00:38 of the potential for life on exoplanets. Yes,
00:00:38 --> 00:00:41 there is one in the news at the moment. We'll
00:00:41 --> 00:00:43 do an update on M20, 24 yr, uh
00:00:43 --> 00:00:46 4. The odds of it hitting us have
00:00:46 --> 00:00:49 halved and SpaceX satellites
00:00:49 --> 00:00:52 raining down on our atmosphere. Uh, what does
00:00:52 --> 00:00:54 that mean? We'll tell you on this episode
00:00:54 --> 00:00:56 of space. Space nuts.
00:00:56 --> 00:00:59 Generic: 15 seconds. Guidance is internal.
00:00:59 --> 00:01:01 10, 9. Ignition
00:01:02 --> 00:01:04 sequence start. Uh, space nuts. 5, 4, 3,
00:01:04 --> 00:01:07 2. 1, 2, 3, 4, 5, 5, 4,
00:01:07 --> 00:01:10 3, 2, 1. Space nuts. Astronauts
00:01:10 --> 00:01:12 report it feels good.
00:01:12 --> 00:01:13 Andrew Dunkley: And he's back again, surprisingly.
00:01:13 --> 00:01:16 It's Jonti Horner, professor of Astrophysics
00:01:16 --> 00:01:17 at the University of Southern Queensland.
00:01:17 --> 00:01:18 Jonti. Hello.
00:01:19 --> 00:01:20 Jonti Horner: G'day. How are you going?
00:01:20 --> 00:01:22 Andrew Dunkley: I am well. How are you?
00:01:22 --> 00:01:24 Jonti Horner: I'm getting there. I've never got the hang of
00:01:24 --> 00:01:25 mornings. I think I'm a bit like the um,
00:01:26 --> 00:01:27 characters from the Hitchhiker's Guide.
00:01:27 --> 00:01:29 Except for me it's mornings. It's not
00:01:29 --> 00:01:30 Mondays, it's mornings.
00:01:30 --> 00:01:33 Andrew Dunkley: Yes, I, I used to be like that and then
00:01:33 --> 00:01:35 I started in breakfast radio and did it for
00:01:35 --> 00:01:38 30 years. So I, I eventually got used to
00:01:38 --> 00:01:39 being up at Sparrows.
00:01:41 --> 00:01:43 Jonti Horner: The breakfast shift does not sound fun.
00:01:44 --> 00:01:47 Andrew Dunkley: Uh, I enjoyed it but that was just me. I
00:01:47 --> 00:01:48 don't know if anyone else did, especially the
00:01:48 --> 00:01:50 audience. Boom, boom.
00:01:50 --> 00:01:50 Jonti Horner: Uh.
00:01:52 --> 00:01:54 Andrew Dunkley: All right, uh, let us get into it and we're
00:01:54 --> 00:01:56 going to start off with this discovery, um,
00:01:57 --> 00:01:59 of a megastructure which has uh,
00:01:59 --> 00:02:02 been uh, in the news
00:02:02 --> 00:02:05 over the last week or so and it's,
00:02:05 --> 00:02:08 it's called Quipu. We'll explain why it's
00:02:08 --> 00:02:09 called that soon. But this is a
00:02:10 --> 00:02:12 megastructure, uh, of natural formation in
00:02:12 --> 00:02:15 the universe. The enormity of this
00:02:15 --> 00:02:17 is mind splittingly
00:02:17 --> 00:02:18 amazing.
00:02:19 --> 00:02:21 Jonti Horner: Yes, yes it is. It's one of those things that
00:02:21 --> 00:02:23 just makes your head hurt like a lot of
00:02:23 --> 00:02:26 things in cosmology. Now I'll happily hold my
00:02:26 --> 00:02:27 hands up right at the start and say my
00:02:27 --> 00:02:29 expertise is on the parts of the universe
00:02:29 --> 00:02:32 that are a lot closer than this. So I'm not a
00:02:32 --> 00:02:34 cosmologist, and if there are cosmologists
00:02:34 --> 00:02:35 listening in or people who are cosmology
00:02:35 --> 00:02:38 enthusiasts and I get something wrong, please
00:02:38 --> 00:02:41 don't be too critical. Um, because, you
00:02:41 --> 00:02:43 know, the size of the things that I don't
00:02:43 --> 00:02:45 know in cosmology is enormous. M just like
00:02:45 --> 00:02:48 the subject itself. But this is a really
00:02:48 --> 00:02:51 interesting one. When we think about the
00:02:51 --> 00:02:53 universe, you see all these wonderful
00:02:53 --> 00:02:56 simulations that come out of our models of
00:02:56 --> 00:02:58 how the universe works that people produce
00:02:58 --> 00:03:01 all the time. And, um, you can almost see
00:03:01 --> 00:03:03 videos on fabulous documentary series where
00:03:03 --> 00:03:05 they start at the scale of an atom and keep
00:03:05 --> 00:03:07 zooming out, and you eventually get to the
00:03:07 --> 00:03:10 person and keep zooming out. And the scale of
00:03:10 --> 00:03:13 cosmology is roughly the
00:03:13 --> 00:03:15 same scale compared to a human being, that a
00:03:15 --> 00:03:17 human being is compared to an atom. So that's
00:03:17 --> 00:03:19 the kind of size scale we're talking about
00:03:19 --> 00:03:22 here, which is the study of the ridiculously
00:03:22 --> 00:03:24 big. But as you zoom out from that human
00:03:24 --> 00:03:26 being on the earth, you get the solar system,
00:03:26 --> 00:03:28 then you get the local stars, then you get
00:03:28 --> 00:03:31 our galaxy. And then as you move out, you get
00:03:31 --> 00:03:33 structures of galaxies together. So you get
00:03:33 --> 00:03:36 small clusters of galaxies, and those small
00:03:36 --> 00:03:38 clusters hang together in bigger clusters
00:03:38 --> 00:03:41 that gather together in superclusters. And
00:03:41 --> 00:03:43 they, for a long time, were kind of the
00:03:43 --> 00:03:44 biggest structures we saw in the universe.
00:03:44 --> 00:03:47 But then as you zoom out further, you start
00:03:47 --> 00:03:50 seeing these structures like walls and
00:03:50 --> 00:03:53 filaments, where those clusters and super
00:03:53 --> 00:03:55 clusters of galaxies are themselves forming
00:03:55 --> 00:03:58 structures with huge voids in between. So on
00:03:58 --> 00:03:59 this kind of scale, when you see those
00:03:59 --> 00:04:02 simulations, it looks almost like a view of
00:04:02 --> 00:04:05 a sponge. So if you've had
00:04:05 --> 00:04:08 a sponge in your bath, the sponge
00:04:08 --> 00:04:10 is a lot of open air spaces
00:04:11 --> 00:04:13 surrounded by lots of solid material. And all
00:04:13 --> 00:04:15 the solid material is in contact with all the
00:04:15 --> 00:04:17 solid material, but all the air is in contact
00:04:17 --> 00:04:19 with all the air. So you could put a bit of
00:04:19 --> 00:04:20 string and go all the way through the sponge,
00:04:20 --> 00:04:22 through the air holes, and come out the other
00:04:22 --> 00:04:25 side and m that's kind of what this view
00:04:25 --> 00:04:27 of the universe looks like. It sees long
00:04:27 --> 00:04:30 filaments and walls all connected
00:04:30 --> 00:04:32 to one another with these enormous voids of
00:04:32 --> 00:04:35 empty space between them. That's the context
00:04:35 --> 00:04:37 we're talking about here. So the team of
00:04:37 --> 00:04:39 researchers who studied this have been
00:04:39 --> 00:04:42 carrying out observations using an X ray
00:04:42 --> 00:04:44 survey looking at very high energy
00:04:44 --> 00:04:47 electromagnetic radiation that's produced
00:04:47 --> 00:04:49 from incredibly hot gas in the most massive
00:04:49 --> 00:04:52 clusters of galaxies. Enormous structures
00:04:52 --> 00:04:55 themselves, and they've looked at a region
00:04:55 --> 00:04:58 about 250 million parsecs across in
00:04:58 --> 00:05:00 all directions, maybe a bit more,
00:05:00 --> 00:05:03 looking for the biggest structures they can
00:05:03 --> 00:05:05 find in that region. And they've identified
00:05:05 --> 00:05:07 four of these, what they're calling
00:05:07 --> 00:05:09 superstructures. And their superstructures
00:05:09 --> 00:05:11 are megastructures because they are bigger
00:05:11 --> 00:05:13 than normal structures. They're structures
00:05:13 --> 00:05:15 made of structures made of superclusters made
00:05:15 --> 00:05:18 of clusters made of local clusters made of
00:05:18 --> 00:05:21 galaxies. On we go all the way down
00:05:21 --> 00:05:24 again. Now, these four structures that
00:05:24 --> 00:05:26 they found between them contain
00:05:26 --> 00:05:29 45% of all the galaxy clusters. They could
00:05:29 --> 00:05:32 see 30% of all the galaxies and 25%
00:05:32 --> 00:05:35 of all the matter, but they only occupy about
00:05:35 --> 00:05:37 13% of the volume. So that gives you the idea
00:05:37 --> 00:05:40 of lots of empty space with these filaments
00:05:40 --> 00:05:43 around it. The biggest of these, this is
00:05:43 --> 00:05:45 someone quipu that's getting all the
00:05:45 --> 00:05:48 attention is ridiculous. They talk
00:05:48 --> 00:05:51 about it being 2000-000000-00000
00:05:51 --> 00:05:54 times the mass of the sun. So if you
00:05:54 --> 00:05:56 remember. So for listeners in countries that
00:05:56 --> 00:05:58 do things differently, we're using the kind
00:05:58 --> 00:06:01 of British scale million billion system here.
00:06:01 --> 00:06:03 So a million is 10 to the six one with six
00:06:03 --> 00:06:06 zeros after it. A billion is a thousand
00:06:06 --> 00:06:09 million. So that's 10 to the 9. A trillion
00:06:09 --> 00:06:12 is a thousand billion or a million million.
00:06:12 --> 00:06:14 That's 10 to the 12. A quadrillion
00:06:14 --> 00:06:17 is a thousand trillion or a million billion
00:06:17 --> 00:06:20 or a billion million. So it's 10 to the 15,
00:06:20 --> 00:06:23 200 of those means this is 2 times 10
00:06:23 --> 00:06:26 to the 17 or 2 with 17
00:06:26 --> 00:06:29 zeros after it times the mass of the Sun. Now
00:06:29 --> 00:06:31 that's a number that is bound to make your
00:06:31 --> 00:06:33 head hurt. So I converted that down by
00:06:33 --> 00:06:36 looking at how many Milky Ways that would be.
00:06:36 --> 00:06:39 And that would be something like 130
00:06:39 --> 00:06:41 times the mass of our galaxy.
00:06:42 --> 00:06:45 So stupidly big numbers it is
00:06:45 --> 00:06:47 spread over a distance. It's a big long
00:06:47 --> 00:06:50 feature, about 400 megaparsecs
00:06:50 --> 00:06:52 long. So one parsec is
00:06:53 --> 00:06:55 perversely the distance
00:06:55 --> 00:06:58 that an object would be away from
00:06:58 --> 00:07:01 the Earth if its parallax, as
00:07:01 --> 00:07:03 the Earth goes around the sun, was 1/ arc
00:07:03 --> 00:07:05 second. It's a really obscure unit of
00:07:05 --> 00:07:08 measurement. It makes sense when you're doing
00:07:08 --> 00:07:10 the maths of measuring distance, but it's not
00:07:10 --> 00:07:12 particularly user friendly. It's a bit like
00:07:12 --> 00:07:15 talking in feet. Light years is a bit like
00:07:15 --> 00:07:17 talking in meters. Same kind of thing. Most
00:07:17 --> 00:07:19 people find light years more straightforward
00:07:19 --> 00:07:21 to visualize, but where one light year is the
00:07:21 --> 00:07:24 time it takes light to travel in one year,
00:07:24 --> 00:07:27 and there are 3.26 light years in one
00:07:27 --> 00:07:29 parsec. So 400
00:07:29 --> 00:07:32 megaparsecs is 1.3
00:07:32 --> 00:07:35 billion light years long. So in other words,
00:07:35 --> 00:07:37 light leaving one end of this structure will
00:07:37 --> 00:07:39 take 1.3 billion years
00:07:40 --> 00:07:43 or, uh, 1300 million years to go from one end
00:07:43 --> 00:07:45 to the other. So it's an enormous, enormous
00:07:45 --> 00:07:48 structure. Now, that's all well and good, and
00:07:48 --> 00:07:50 it's fabulous cataloging the biggest and the
00:07:50 --> 00:07:52 most massive and the brightest. And I know a
00:07:52 --> 00:07:54 lot of people, I do this occasionally. Look
00:07:54 --> 00:07:56 up Wikipedia articles like, what's the most
00:07:56 --> 00:07:58 massive star? What's the most luminous star?
00:07:58 --> 00:08:00 Things like that. But it's also really
00:08:00 --> 00:08:02 valuable to know this kind of stuff because
00:08:02 --> 00:08:05 if you study these big structures, that gives
00:08:05 --> 00:08:06 us information that we can compare to the
00:08:06 --> 00:08:09 models that are based on our current
00:08:09 --> 00:08:12 understanding of the universe to see if those
00:08:12 --> 00:08:14 models make sense. And, uh, the good thing is
00:08:14 --> 00:08:16 that the current models of how the universe
00:08:16 --> 00:08:19 work predict structures like this. So this
00:08:19 --> 00:08:21 is very much in line with what people
00:08:21 --> 00:08:23 expected to see. And that's a really good
00:08:23 --> 00:08:26 part of how science works. It's very much a
00:08:26 --> 00:08:28 case of our models predicted this and now
00:08:28 --> 00:08:30 you've seen it, that makes us happy because
00:08:30 --> 00:08:33 it means the models are working correctly. It
00:08:33 --> 00:08:35 also is the kind of information that's really
00:08:35 --> 00:08:38 useful for people studying the Big Bang and
00:08:38 --> 00:08:40 more ancient universe. Because structures
00:08:40 --> 00:08:43 like this are sufficiently massive, then they
00:08:43 --> 00:08:45 will influence our view of what is beyond.
00:08:45 --> 00:08:47 You get gravitational lensing from the big
00:08:47 --> 00:08:50 objects. You also even get. And, um, I don't
00:08:50 --> 00:08:52 fully understand how this works, but you also
00:08:52 --> 00:08:55 get the pollution of the cosmic microwave
00:08:55 --> 00:08:58 background, which is the last hiss of the Big
00:08:58 --> 00:09:01 Bang. It's our image of the
00:09:01 --> 00:09:03 last surface 300 years after the Big
00:09:04 --> 00:09:06 Bang, where the universe became transparent.
00:09:06 --> 00:09:09 And we found little bits of structure in that
00:09:09 --> 00:09:11 which are important for us understanding how
00:09:11 --> 00:09:14 the modern structure of the universe formed.
00:09:14 --> 00:09:17 But that structure is polluted by the
00:09:17 --> 00:09:19 influence of these foreground objects
00:09:20 --> 00:09:22 by something called the integrated Sachs
00:09:22 --> 00:09:23 Wolfe effect. And I have no idea how that
00:09:23 --> 00:09:26 works, to be brutally honest. But
00:09:26 --> 00:09:28 if you've got something like that, that
00:09:28 --> 00:09:31 pollutes our view of what's beyond. And we
00:09:31 --> 00:09:33 want to understand what's beyond. The better
00:09:33 --> 00:09:35 we can see the foreground, the better we can
00:09:35 --> 00:09:36 account for it when we're studying the
00:09:36 --> 00:09:39 background. So getting studies of this a.
00:09:39 --> 00:09:41 It's fascinating. It's a really good test for
00:09:41 --> 00:09:44 our models. But it also allows us in the
00:09:44 --> 00:09:47 future to get a better handle on how things
00:09:47 --> 00:09:49 like the cosmic microwave background really
00:09:49 --> 00:09:52 look when you filter out the foreground mess.
00:09:52 --> 00:09:54 And I guess the equivalent here will be like
00:09:54 --> 00:09:56 having a light pollution filter for people
00:09:56 --> 00:09:59 who are astronomy photography enthusiasts.
00:09:59 --> 00:10:01 You've got a murky, light polluted sky, but
00:10:01 --> 00:10:03 if you put a light pollution filter on the
00:10:03 --> 00:10:05 front of your lens, you can cancel out that
00:10:05 --> 00:10:07 foreground mess and get a much better view of
00:10:07 --> 00:10:10 what's beyond. This will enable us to do that
00:10:10 --> 00:10:12 same kind of filtering when we're looking at
00:10:12 --> 00:10:13 the microwave background.
00:10:13 --> 00:10:16 So I think it's a fabulous story, full of
00:10:16 --> 00:10:19 numbers what make your head hurt. Quite.
00:10:19 --> 00:10:22 Andrew Dunkley: They're massive numbers. It's just uh,
00:10:22 --> 00:10:25 just incredible. Now why is
00:10:25 --> 00:10:27 it called Quipu?
00:10:27 --> 00:10:29 Jonti Horner: This is partially because of the structure.
00:10:29 --> 00:10:32 So it looks like a long thick filament with
00:10:32 --> 00:10:34 thinner filaments branching off the sides of
00:10:34 --> 00:10:36 it. The authors of this paper
00:10:36 --> 00:10:39 noticed that this looks very similar to the
00:10:39 --> 00:10:41 traditional counting instrument of the Incan
00:10:41 --> 00:10:44 people in Peru. Um, which was essentially
00:10:44 --> 00:10:46 they did their counting using knotted ropes
00:10:46 --> 00:10:48 and ah, that knotted rope counting device was
00:10:48 --> 00:10:51 a Quipu. So it's quite a nice nod to the
00:10:51 --> 00:10:54 traditional culture of that area in
00:10:54 --> 00:10:56 Peru. Again, I'm not an anthropologist or an
00:10:56 --> 00:10:58 archaeologist, I don't really know much more
00:10:58 --> 00:11:00 about it than that, but I think it is a
00:11:00 --> 00:11:03 really nice nod to a different culture.
00:11:03 --> 00:11:05 And as we've talked about in previous weeks,
00:11:05 --> 00:11:07 this idea of embracing all the cultures of
00:11:07 --> 00:11:09 the Earth in our studies going forward is
00:11:09 --> 00:11:11 really gaining traction. It's a really nice
00:11:11 --> 00:11:12 way of doing things, I think.
00:11:12 --> 00:11:15 Andrew Dunkley: Absolutely, yes, I'd agree. And uh, the
00:11:15 --> 00:11:18 Incans have a, um, strong history
00:11:18 --> 00:11:21 with astronomy so uh, that ties
00:11:21 --> 00:11:24 in well too. So yeah, fascinating.
00:11:24 --> 00:11:26 If you would like to chase up that story. It
00:11:26 --> 00:11:29 was published in Astronomy and Astrophysics,
00:11:29 --> 00:11:31 the journal. You can also read about
00:11:31 --> 00:11:32 it at the
00:11:32 --> 00:11:35 arxiv.org website. That's
00:11:35 --> 00:11:37 arXiv. I learned that last week.
00:11:38 --> 00:11:40 arxiv.org uh, yes,
00:11:41 --> 00:11:43 there was um, um, a lot of involvement from
00:11:43 --> 00:11:46 the Max Planck Institute in um, in
00:11:46 --> 00:11:48 running this. The author was Hans
00:11:49 --> 00:11:51 Boehringer. So uh, you might want to look
00:11:51 --> 00:11:52 that up.
00:11:56 --> 00:11:57 Space nuts.
00:11:57 --> 00:12:00 Uh, now, uh, let's move on to our next
00:12:00 --> 00:12:03 story. This is a pet peeve peeve story,
00:12:03 --> 00:12:05 um, which Jonti wanted to talk about. And
00:12:05 --> 00:12:07 look, I'm not surprised that
00:12:08 --> 00:12:11 bothers some people, uh, because I, I
00:12:11 --> 00:12:14 have often referred to the popular press
00:12:14 --> 00:12:16 when doing this podcast and how they latch
00:12:16 --> 00:12:19 onto something that isn't quite the story
00:12:20 --> 00:12:22 but it makes a great headline and that's what
00:12:22 --> 00:12:24 this is. Overselling the potential for life
00:12:25 --> 00:12:26 on exoplanets.
00:12:26 --> 00:12:28 Jonti Horner: Yeah, yeah, it's.
00:12:28 --> 00:12:29 Andrew Dunkley: And one in particular in the news at the
00:12:29 --> 00:12:30 moment.
00:12:30 --> 00:12:31 Jonti Horner: Well it's something that's niggled at me for
00:12:31 --> 00:12:33 a while. It should be said that the criticism
00:12:33 --> 00:12:35 here is not of the research done by these
00:12:35 --> 00:12:37 authors. They've done a fabulous bit of
00:12:37 --> 00:12:38 research and if you look at the paper,
00:12:39 --> 00:12:41 they've got the balance right. That's fine.
00:12:41 --> 00:12:43 But there is a very common trend,
00:12:44 --> 00:12:45 particularly among press offices at
00:12:45 --> 00:12:48 universities and also around
00:12:48 --> 00:12:50 a lot of media sites that rely on clicks for
00:12:50 --> 00:12:53 their income, to talk about
00:12:54 --> 00:12:56 the most habitable planet ever discovered. We
00:12:56 --> 00:12:58 found the most Earth, uh, like, planet ever.
00:12:58 --> 00:13:00 And the reports on this planet are not quite
00:13:00 --> 00:13:02 that bad, but they have been talking about
00:13:02 --> 00:13:04 potentially habitable planet discovered
00:13:04 --> 00:13:06 around nearby star, because that gets the
00:13:06 --> 00:13:09 clicks. And before we dig into this story,
00:13:09 --> 00:13:11 the reason that this niggles at me is that
00:13:11 --> 00:13:14 people are getting exo Earth fatigue and also
00:13:14 --> 00:13:17 life elsewhere fatigue. So
00:13:17 --> 00:13:20 by reporting things when we haven't actually
00:13:20 --> 00:13:21 found what the reports are saying, it creates
00:13:21 --> 00:13:23 this opinion that the science is already
00:13:23 --> 00:13:26 done. We've already discovered the autumn
00:13:26 --> 00:13:28 stuff. So when we finally find a planet that
00:13:28 --> 00:13:30 really does have life on it, or when we
00:13:30 --> 00:13:31 finally find a planet that genuinely is
00:13:31 --> 00:13:34 Earth, ah, 2.0. That'll be exciting.
00:13:34 --> 00:13:36 I'll be thrilled. We've finally got something
00:13:36 --> 00:13:37 to talk about and everybody will be kind of
00:13:37 --> 00:13:39 the boy who cried wolf. Well, you've told us
00:13:39 --> 00:13:40 that you've done this a million times
00:13:40 --> 00:13:43 already. Yeah, and it's easy. Why are you
00:13:43 --> 00:13:45 interested? You know, it's
00:13:45 --> 00:13:48 also the fact that we
00:13:48 --> 00:13:50 basically don't know enough to make these
00:13:50 --> 00:13:52 statements yet. So when you see a headline
00:13:52 --> 00:13:54 like, we found the most Earth, uh, like,
00:13:54 --> 00:13:56 planet ever. What it's actually telling you
00:13:56 --> 00:13:58 is we found a planet that's about the same
00:13:58 --> 00:14:01 diameter as the Earth, and that's it.
00:14:01 --> 00:14:03 So it's like me being an alien and visiting
00:14:03 --> 00:14:05 the Earth and scanning the oceans and saying,
00:14:05 --> 00:14:07 I found the most human, like, creature ever.
00:14:07 --> 00:14:09 It's about the same length and it's about the
00:14:09 --> 00:14:11 same weight and it's about the same size.
00:14:11 --> 00:14:14 It's called a dolphin. Nothing like a
00:14:14 --> 00:14:15 human whatsoever, but it's about the same
00:14:15 --> 00:14:18 size and about the same mass. So it's the
00:14:18 --> 00:14:21 most human, like, animal ever. So I get a
00:14:21 --> 00:14:23 bit grumpy. And there's a lot that goes into
00:14:23 --> 00:14:25 habitability that I can talk about a little
00:14:25 --> 00:14:27 bit later on, which is why I think this is a
00:14:27 --> 00:14:30 much more complex problem. And for me, that
00:14:30 --> 00:14:31 makes it much more interesting, a lot more
00:14:31 --> 00:14:34 research to do. But it does mean that when
00:14:34 --> 00:14:36 you get a claim saying, potentially habitable
00:14:36 --> 00:14:38 planet, or the most habitable planet we've
00:14:38 --> 00:14:40 ever found yet People even publishing
00:14:40 --> 00:14:42 articles about super habitable planets that
00:14:42 --> 00:14:44 are more suitable for life than Earth. I
00:14:44 --> 00:14:46 don't think you can say any of that. Aha.
00:14:46 --> 00:14:49 Uh, in this particular case, it is an
00:14:49 --> 00:14:51 interesting story. There is a star called 82
00:14:51 --> 00:14:54 Erudani, which also goes by the name HD
00:14:54 --> 00:14:57 20794. You know, astronomers love
00:14:57 --> 00:15:00 our acronyms and our barcodes. This
00:15:00 --> 00:15:02 is a star that you can see with the naked eye
00:15:02 --> 00:15:03 in the constellation of Eridanus, but it's
00:15:03 --> 00:15:05 not particularly bright. It's about magnitude
00:15:05 --> 00:15:08 4, 4 and a half. And for a while we've known
00:15:08 --> 00:15:10 it had two planets around it. But it's been
00:15:10 --> 00:15:13 monitored by the High Accuracy Radial
00:15:13 --> 00:15:15 Velocity Planet Search for Spectrograph HARPS
00:15:15 --> 00:15:18 in Chile. And HARPS is an incredible
00:15:18 --> 00:15:21 instrument. It allows you to measure
00:15:21 --> 00:15:24 the velocity of a star. So you take the
00:15:24 --> 00:15:26 light from a star, you break it up into its
00:15:26 --> 00:15:28 component colors, and laced across that
00:15:28 --> 00:15:31 spectrum is a series of dark lines. And
00:15:31 --> 00:15:32 those dark lines, which we call the
00:15:32 --> 00:15:35 Fraunhofer absorption lines, are, uh, the
00:15:35 --> 00:15:37 fingerprint of all the different atoms and
00:15:37 --> 00:15:39 molecules in the star's outer atmosphere.
00:15:39 --> 00:15:41 Every atomic species, every molecular species
00:15:41 --> 00:15:44 absorbs light at a very specific, unique set
00:15:44 --> 00:15:47 of wavelengths. And it imprints this dark set
00:15:47 --> 00:15:49 of lines across the star spectrum. Now, if
00:15:49 --> 00:15:52 the star's moving towards us, its light will
00:15:52 --> 00:15:54 be blue shifted. So all of those lines will
00:15:54 --> 00:15:56 move a little bit to the blue because of the
00:15:56 --> 00:15:58 Doppler effect. If it's moving away from us,
00:15:58 --> 00:16:00 the light will be redshifted. So it'll move a
00:16:00 --> 00:16:02 bit to the red again with the Doppler effect.
00:16:02 --> 00:16:04 And I've talked about this before, this is
00:16:04 --> 00:16:06 the equivalent of having the siren coming
00:16:06 --> 00:16:08 towards you and hearing it high pitched and
00:16:08 --> 00:16:11 fast with Nino, Nino, Nino and uh, then it
00:16:11 --> 00:16:13 moving away and you're hearing it low pitched
00:16:13 --> 00:16:16 and slow with Nino, Nino to do with the
00:16:16 --> 00:16:18 waves getting stretched or compressed
00:16:18 --> 00:16:21 essentially. Now what that means is if we
00:16:21 --> 00:16:22 measure the positions of these lines
00:16:22 --> 00:16:24 accurately enough, we can measure the change
00:16:24 --> 00:16:26 in the speed of the star as it moves around
00:16:27 --> 00:16:29 by seeing those lines move. So we can look at
00:16:30 --> 00:16:32 stars and see them wobbling and infer the
00:16:32 --> 00:16:34 presence of planets that we can't see by how
00:16:34 --> 00:16:37 those planets pull those stars around. But
00:16:37 --> 00:16:38 there are limits to this. There's a lot of
00:16:38 --> 00:16:41 challenges involved. So facility like the one
00:16:41 --> 00:16:42 we've got at the University of Southern
00:16:42 --> 00:16:45 Queensland, which is actually the Southern
00:16:45 --> 00:16:47 hemisphere's only dedicated exoplanet search
00:16:47 --> 00:16:50 facility, we can get an accuracy
00:16:50 --> 00:16:52 where we can measure the wobble of stars down
00:16:52 --> 00:16:55 to about two or three Meters a second. So we
00:16:55 --> 00:16:57 could see a star, ah, changing in speed by
00:16:57 --> 00:16:59 about as much as someone going at a very
00:16:59 --> 00:17:02 gentle jog. What that means is we
00:17:02 --> 00:17:04 could not find these particular planets,
00:17:04 --> 00:17:06 they're just much too hard. But the HAARP
00:17:06 --> 00:17:09 spectrograph is on a much bigger telescope in
00:17:09 --> 00:17:12 a much better location and it's an incredibly
00:17:12 --> 00:17:15 accurate piece of kit. So it lets you get
00:17:15 --> 00:17:17 down to sub meter per second measurements,
00:17:18 --> 00:17:20 which is breathtaking. Put that in
00:17:20 --> 00:17:21 perspective. We're looking at stars here
00:17:22 --> 00:17:24 whose distances are quadrillions ah, of
00:17:24 --> 00:17:26 kilometers away. Again using the units from
00:17:26 --> 00:17:29 before. These are stars where the light has
00:17:29 --> 00:17:32 taken decades to reach us and we are
00:17:32 --> 00:17:34 able to measure their velocity so accurately
00:17:34 --> 00:17:37 that we can see changes in that velocity of
00:17:37 --> 00:17:40 50 centimeters a second. Wow, that's just
00:17:40 --> 00:17:43 astonishing precision and that's what the
00:17:43 --> 00:17:45 team have done. So they've observed this
00:17:45 --> 00:17:47 star, uh, HD 20794
00:17:48 --> 00:17:50 for a number of years with haps getting more
00:17:50 --> 00:17:53 and more data tracking how the speed changes.
00:17:53 --> 00:17:55 And in the past they'd found two planets and
00:17:55 --> 00:17:57 hints of a third and they've now confirmed
00:17:57 --> 00:18:00 that third one. That third planet, HD2.0, uh,
00:18:00 --> 00:18:03 794-D is making the star
00:18:03 --> 00:18:06 wobble with its speed changing by just
00:18:06 --> 00:18:08 50cm a second plus and minus
00:18:09 --> 00:18:12 over a period of about 700 days. So
00:18:12 --> 00:18:14 you're watching for 700 days, you get rid of
00:18:14 --> 00:18:16 all the other noise, the star wobbling around
00:18:16 --> 00:18:19 itself, just oscillating like a shruk
00:18:19 --> 00:18:21 bell. You get rid of the orbits of the two
00:18:21 --> 00:18:23 inner planets which are causing it to wobble
00:18:23 --> 00:18:25 by a similar amount with a different period
00:18:25 --> 00:18:28 and you're left with a tiny wobble of plus or
00:18:28 --> 00:18:30 minus 50cm a second that takes 700 days
00:18:31 --> 00:18:33 to complete once. And that's what they found.
00:18:33 --> 00:18:36 So this is our planet. It's a planet about
00:18:36 --> 00:18:39 six times the mass of the Earth, at least
00:18:39 --> 00:18:41 might be more than that. We don't know how
00:18:41 --> 00:18:43 edge on or tilted the orbit is because we're
00:18:43 --> 00:18:45 not seeing it transit. If it's tilted by 30
00:18:46 --> 00:18:48 degrees, the mass of this planet will be
00:18:48 --> 00:18:50 higher. If it's tilted by 60 degrees instead
00:18:50 --> 00:18:52 of being 6 earth masses, it'll be 12 earth
00:18:52 --> 00:18:55 masses. So this is a minimum mass.
00:18:56 --> 00:18:58 So it's what we call a super Earth, ah, or a
00:18:58 --> 00:19:01 mini Neptune. It's much more massive than our
00:19:01 --> 00:19:04 planet and certainly larger than our planet.
00:19:04 --> 00:19:07 It's moving on an orbit that if you
00:19:07 --> 00:19:09 calculated its semi major axis,
00:19:09 --> 00:19:12 the length of the ellipse, half the length of
00:19:12 --> 00:19:14 the ellipse, which sets a period that will
00:19:15 --> 00:19:17 put it in the habitable zone, um, that's what
00:19:17 --> 00:19:19 the paper says. Now, the habitable zone I'll
00:19:19 --> 00:19:22 get into in a second. But this planet moves
00:19:22 --> 00:19:24 on a very elongated orbit, so its distance
00:19:24 --> 00:19:27 from its star is changing by a factor of two
00:19:27 --> 00:19:29 from its closest to the star to the furthest
00:19:29 --> 00:19:31 away. Now, if you scale that up to the solar
00:19:31 --> 00:19:33 system and put it in the same place,
00:19:33 --> 00:19:35 temperature wise, as it is in its system.
00:19:35 --> 00:19:37 Now, if you put it in the solar system so
00:19:37 --> 00:19:39 that its orbit had that same temperature
00:19:39 --> 00:19:42 range, that would mean when it's closest to
00:19:42 --> 00:19:44 its star, it's as close as Venus. When it's
00:19:44 --> 00:19:46 furthest from its star, it's further out than
00:19:46 --> 00:19:48 Mars. You're going to have
00:19:48 --> 00:19:51 extreme, extreme temperature variability on
00:19:51 --> 00:19:54 this planet. Now, the habitable zone, um,
00:19:54 --> 00:19:56 is always thrown out for these planets. It's
00:19:56 --> 00:19:59 that Goldilocks idea. If you have a planet
00:19:59 --> 00:20:01 that's at the right distance from a star, the
00:20:01 --> 00:20:03 temperature will be not too hot and not too
00:20:03 --> 00:20:05 cold, and it'll be just right for liquid
00:20:05 --> 00:20:07 water on the surface. The subtle
00:20:07 --> 00:20:10 implication buried in this is not actually
00:20:11 --> 00:20:13 what I just said, but it's rather. If you
00:20:13 --> 00:20:15 took the Earth as the Earth is
00:20:15 --> 00:20:18 today, and dropped it where this planet is,
00:20:18 --> 00:20:20 would the Earth, uh, still have liquid water
00:20:20 --> 00:20:22 on its surface? Now, that's a subtle
00:20:23 --> 00:20:24 difference. But to illustrate it, if you
00:20:24 --> 00:20:27 think about the solar system, the
00:20:27 --> 00:20:29 boundaries of the habitable zone are usually
00:20:29 --> 00:20:31 set by looking at Venus and Mars. That's
00:20:31 --> 00:20:33 what's motivated this. The calculations are
00:20:33 --> 00:20:35 more robust, uh, now, but that's about where
00:20:35 --> 00:20:38 it washes out. Venus, closer to the sun than
00:20:38 --> 00:20:41 us, is super hot. 450 degrees centigrade on
00:20:41 --> 00:20:43 the surface and clearly not habitable. Mars
00:20:43 --> 00:20:45 is super cold. It's too cold for life. It's
00:20:45 --> 00:20:47 outside the habitable zone. The Earth's in
00:20:47 --> 00:20:49 the middle, and it's just right. But to
00:20:49 --> 00:20:52 illustrate why it's not so simple, imagine a
00:20:52 --> 00:20:53 thought experiment where you swap Venus and
00:20:53 --> 00:20:56 Mars around. If you put Mars where Venus is,
00:20:56 --> 00:20:59 it's got a thinner atmosphere than we do, so
00:20:59 --> 00:21:01 it's got less of a greenhouse effect. So it
00:21:01 --> 00:21:04 would probably remain clement where Venus
00:21:04 --> 00:21:06 would overheat. Similarly, if you put Venus
00:21:06 --> 00:21:08 where Mars is, Venus has this incredibly
00:21:08 --> 00:21:10 thick atmosphere with an incredibly strong
00:21:10 --> 00:21:13 greenhouse. It will probably still be
00:21:13 --> 00:21:15 habitable. It would still be warm enough
00:21:15 --> 00:21:17 where Mars wouldn't. So this habitable zone
00:21:17 --> 00:21:20 is a much woollier concept than I think most
00:21:20 --> 00:21:23 people realize. And it's
00:21:23 --> 00:21:25 just not really a guideline. It's just an
00:21:26 --> 00:21:28 indication that this could be somewhere worth
00:21:28 --> 00:21:29 looking at. It's not more than that, but it
00:21:29 --> 00:21:31 tends to get played up as being the Holy
00:21:31 --> 00:21:34 Grail. And one is in the habitable zone. It
00:21:34 --> 00:21:36 must therefore have the potential to be
00:21:36 --> 00:21:38 habitable. Whereas in fact, what you're
00:21:38 --> 00:21:40 saying is if you put the Earth on the orbit
00:21:40 --> 00:21:42 that this planet is on, it might still look
00:21:42 --> 00:21:45 like the Earth, except with the planet we're
00:21:45 --> 00:21:46 talking about at the minute. If you put the
00:21:46 --> 00:21:49 Earth on that orbit at, um,
00:21:49 --> 00:21:51 perihelion, when it was closest to the sun,
00:21:51 --> 00:21:53 it would receive a flux from the sun as high
00:21:53 --> 00:21:55 as Venus does. So the oceans would start to
00:21:55 --> 00:21:58 boil. Fortunately, it doesn't spend long at
00:21:58 --> 00:22:00 perihelion. We move quickest when we're
00:22:00 --> 00:22:02 closest to the object. We swing out through
00:22:02 --> 00:22:04 the habitable zone, probably everything's
00:22:04 --> 00:22:06 fine. But you've got bonkers weather because
00:22:06 --> 00:22:08 you're dealing with all that heat you've just
00:22:08 --> 00:22:10 been given. Then you get to your furthest
00:22:10 --> 00:22:12 point from the star and that's when you move
00:22:12 --> 00:22:14 the slowest. So this planet spends probably
00:22:14 --> 00:22:17 more than 50% of its time further from
00:22:17 --> 00:22:19 its star than the outer edge of that
00:22:19 --> 00:22:21 habitable zone by calculation. So those
00:22:21 --> 00:22:24 oceans would freeze and you get this deep,
00:22:24 --> 00:22:25 Game of Thrones style winter. You'd have
00:22:25 --> 00:22:27 everybody going, oh, look, winter is coming.
00:22:28 --> 00:22:30 Everybody's doomed. And then it would swing
00:22:30 --> 00:22:32 back into the star and have a brief furnace
00:22:32 --> 00:22:34 like summer, and then a long cold winter
00:22:34 --> 00:22:37 again. It doesn't sound particularly clement.
00:22:37 --> 00:22:38 You add to that, though, the fact that this
00:22:38 --> 00:22:41 planet is six times the mass of the Earth
00:22:41 --> 00:22:43 means it's going to have a very substantial
00:22:43 --> 00:22:45 atmosphere, and I should say at least six
00:22:45 --> 00:22:47 times the mass of the Earth. A much thicker
00:22:47 --> 00:22:49 atmosphere means a much stronger greenhouse
00:22:49 --> 00:22:52 effect, which means the results of
00:22:52 --> 00:22:54 that extreme insolation, the extreme
00:22:54 --> 00:22:56 radiation at, uh, pericentre when it's
00:22:56 --> 00:22:59 closest to the star, is even more pronounced.
00:22:59 --> 00:23:01 So I don't think it's at all fair to say that
00:23:01 --> 00:23:03 this planet could be potentially habitable.
00:23:03 --> 00:23:05 And in fact, the authors of the paper
00:23:05 --> 00:23:07 themselves don't really say that. What they
00:23:07 --> 00:23:09 do say is, is that this planet crosses the
00:23:09 --> 00:23:11 habitable zone. And, um, because it's a bit
00:23:11 --> 00:23:13 bigger and, um, because it has this big
00:23:13 --> 00:23:16 variation in existence from the star and, um,
00:23:16 --> 00:23:18 because it's around a nearby star, could be a
00:23:18 --> 00:23:21 really good test case for us to practice our
00:23:21 --> 00:23:23 observation techniques to learn more about
00:23:23 --> 00:23:25 atmospheres of planets this size before we
00:23:25 --> 00:23:27 really look at ones that could be habitable
00:23:27 --> 00:23:30 enough like. But this planet certainly isn't
00:23:30 --> 00:23:33 it. And even then there's a whole heap of
00:23:33 --> 00:23:34 Other things that will impact habitability,
00:23:34 --> 00:23:36 which we may or may not have time to go into
00:23:36 --> 00:23:39 today. But the habitable zone really is just
00:23:39 --> 00:23:42 the first of an incredibly long list of
00:23:42 --> 00:23:45 variables that you can slide around that
00:23:45 --> 00:23:46 could influence a habitability. Because all
00:23:46 --> 00:23:48 it's saying is, how hot would the Earth be if
00:23:48 --> 00:23:50 you put it there? Essentially?
00:23:50 --> 00:23:53 Andrew Dunkley: Yeah, yeah. And at six times the size of the
00:23:53 --> 00:23:55 Earth, at least gravity has to be a factor
00:23:55 --> 00:23:57 as well, doesn't it?
00:23:57 --> 00:24:00 Jonti Horner: It does. I mean, if you estimate that
00:24:00 --> 00:24:01 this thing is twice the Earth's diameter and
00:24:01 --> 00:24:04 M, we don't know that because this thing
00:24:04 --> 00:24:06 doesn't transit its star, or we've never seen
00:24:06 --> 00:24:08 it transit its star. So its orbit is almost
00:24:08 --> 00:24:10 certainly not edron, which means its mass is
00:24:10 --> 00:24:12 probably a bit higher than we say that
00:24:12 --> 00:24:14 minimum is. But it means we have no way of
00:24:14 --> 00:24:17 measuring the size. Now, at six Earth
00:24:17 --> 00:24:19 masses or a bit heavier, it's near this
00:24:19 --> 00:24:21 boundary between what we call super Earth or
00:24:21 --> 00:24:23 mini Neptune. Super Earth is a rocky
00:24:23 --> 00:24:26 object with a big thick atmosphere, and mini
00:24:26 --> 00:24:28 Neptune is a big thick atmosphere with a
00:24:28 --> 00:24:29 rocky core. So you can see how that
00:24:29 --> 00:24:32 transitions between them. But if you estimate
00:24:32 --> 00:24:34 for a minute that it is a super Earth with a
00:24:34 --> 00:24:36 bit of a thick atmosphere, you could say,
00:24:36 --> 00:24:38 well, maybe it's twice the diameter of the
00:24:38 --> 00:24:39 Earth. Uh, and, uh, that would kind of make
00:24:40 --> 00:24:42 sense density wise. That would place it a
00:24:42 --> 00:24:44 little bit less dense than the Earth. But
00:24:44 --> 00:24:46 that might make sense because it's a little
00:24:46 --> 00:24:48 bit cooler for a lot of its orbit.
00:24:49 --> 00:24:51 Even in that scenario, the acceleration due
00:24:51 --> 00:24:54 to gravity on its surface will be 50% higher
00:24:54 --> 00:24:57 than that we have on the Earth right now. You
00:24:57 --> 00:24:58 know, so gravity will be stronger. We'd
00:24:58 --> 00:25:01 probably all, if we were there, be squat and
00:25:01 --> 00:25:03 dumpy and grumbling about how heavy we feel
00:25:03 --> 00:25:05 and all the rest of it. You know, I'm heavy
00:25:05 --> 00:25:07 enough already without giving me 50%.
00:25:08 --> 00:25:11 Andrew Dunkley: Yes, no, that's a fair point. But,
00:25:11 --> 00:25:13 uh, yeah, these, these stories are not
00:25:13 --> 00:25:15 uncommon now. And you make a very valid point
00:25:15 --> 00:25:17 that people will just, you know, when the day
00:25:17 --> 00:25:20 comes that we've genuinely got an Earth like
00:25:20 --> 00:25:23 planet Earth 2.0, uh, that could
00:25:23 --> 00:25:26 harbor life. People will go, yeah, right.
00:25:26 --> 00:25:28 Oh, ah, heard it all before.
00:25:28 --> 00:25:31 Jonti Horner: And it's dangerous. And quite often the
00:25:31 --> 00:25:33 researchers involved don't have control of
00:25:33 --> 00:25:35 that story. That's one of the reasons I
00:25:35 --> 00:25:37 love working with websites, like the
00:25:37 --> 00:25:39 conversation, where I control the narrative
00:25:39 --> 00:25:41 when I write articles. But it's also why I
00:25:41 --> 00:25:43 really appreciate our media team here at
00:25:43 --> 00:25:46 unisq because they actually talk to us
00:25:46 --> 00:25:48 when they're writing media releases and a lot
00:25:48 --> 00:25:50 of the bigger universities, the media team
00:25:50 --> 00:25:52 get hold of a paper and they write their own
00:25:52 --> 00:25:54 interpretation of it with, with a couple of
00:25:54 --> 00:25:56 quotes from the authors, but they don't let
00:25:56 --> 00:25:58 the authors read the release. Then you get
00:25:58 --> 00:26:00 journalists who read the media release and
00:26:00 --> 00:26:02 spin it further and you end up from an
00:26:02 --> 00:26:04 article that says, we found a planet that is
00:26:04 --> 00:26:06 interesting to being new. Earth planet has
00:26:06 --> 00:26:09 been found. Life 2.0 is there.
00:26:09 --> 00:26:11 And that's not what anybody actually said.
00:26:12 --> 00:26:13 Andrew Dunkley: No, no, but it's a good way.
00:26:13 --> 00:26:15 Jonti Horner: To get hits and links to your university's
00:26:15 --> 00:26:15 website.
00:26:16 --> 00:26:18 Andrew Dunkley: Exactly. Yeah. Okay. If you'd like to
00:26:18 --> 00:26:21 read up on that, uh, the genuine article I'm
00:26:21 --> 00:26:23 talking about, uh, you can find it in the
00:26:23 --> 00:26:26 journal Astronomy and Astrophys.
00:26:26 --> 00:26:28 You feel better now that you've got that off
00:26:28 --> 00:26:29 your chest, Jon?
00:26:29 --> 00:26:32 Jonti Horner: This is a perpetual rant of mine. I actually
00:26:32 --> 00:26:35 did with my former mentor, Barry Jones, who
00:26:35 --> 00:26:38 passed away about a decade ago now. Um, we
00:26:38 --> 00:26:40 wrote my first ever review paper back in 2010
00:26:40 --> 00:26:43 where I dug into this. So it always used to
00:26:43 --> 00:26:45 bug me that it was just, it's in the
00:26:45 --> 00:26:48 habitable zone, right? That's job done. And
00:26:48 --> 00:26:49 so we wrote this paper where we looked at all
00:26:50 --> 00:26:51 of the other things people have proposed that
00:26:51 --> 00:26:53 could make a planet more habitable or less
00:26:53 --> 00:26:56 habitable, more suitable. And for me, the
00:26:56 --> 00:26:59 thing here is, when we get to do observations
00:26:59 --> 00:27:01 to look for life on these planets, which is
00:27:01 --> 00:27:03 still a bit beyond us, but we're getting
00:27:03 --> 00:27:06 towards that point, those observations are
00:27:06 --> 00:27:07 going to be the hardest observations
00:27:07 --> 00:27:09 humanity's ever had to carry out. You're
00:27:09 --> 00:27:11 talking hundreds or thousands of hours on the
00:27:11 --> 00:27:14 biggest space telescopes, really competitive
00:27:14 --> 00:27:16 time. You're not going to be able to look at
00:27:16 --> 00:27:18 them all. So you're going to have to find a
00:27:18 --> 00:27:20 way to pick the best target. You're going to
00:27:20 --> 00:27:21 have to find a way to whittle down a list of
00:27:21 --> 00:27:23 hundreds or thousands into the best two or
00:27:23 --> 00:27:26 three. And you can't just use the habitables
00:27:26 --> 00:27:28 on there. So I thought, let's look at all the
00:27:28 --> 00:27:30 different things that can impact habitability
00:27:30 --> 00:27:32 to see if you can turn them almost into the
00:27:32 --> 00:27:34 volume sliders on the mixing desk of the
00:27:34 --> 00:27:36 dj, right? You can turn them up, turn them
00:27:36 --> 00:27:39 down, and see which planet gets the best
00:27:39 --> 00:27:41 score overall when you factor all of them in.
00:27:42 --> 00:27:43 And, um, some of them are things we can't yet
00:27:43 --> 00:27:45 observe. Some of them are things you might
00:27:45 --> 00:27:47 have to model with computer modeling, like I
00:27:47 --> 00:27:50 do. But it can be everything from the nature
00:27:50 --> 00:27:53 of the star itself, how Variable it is all
00:27:53 --> 00:27:54 the way through to the other planets in the
00:27:54 --> 00:27:56 system, what their gravity does, how much
00:27:56 --> 00:27:59 debris there is, and even down to the planet
00:27:59 --> 00:28:00 itself. Whether it has plate tectonics,
00:28:00 --> 00:28:02 whether it has a magnetic field, all of these
00:28:02 --> 00:28:04 things will factor in. It's not just as
00:28:04 --> 00:28:07 simple as where do you place it? Is it in the
00:28:07 --> 00:28:08 right spot?
00:28:09 --> 00:28:12 Andrew Dunkley: Valid point. All right. Uh, yeah, as
00:28:12 --> 00:28:14 I said, you can uh, chase that story up at
00:28:14 --> 00:28:16 Astronomy and Astrophysics. Uh, you could
00:28:16 --> 00:28:18 probably find it just about anywhere online.
00:28:18 --> 00:28:21 Uh, there's an article on Space.com as
00:28:21 --> 00:28:24 well. This is Space Nuts with Andrew Dunkley
00:28:24 --> 00:28:25 and John Horner.
00:28:30 --> 00:28:31 Space Nuts, right.
00:28:31 --> 00:28:33 Our next story, which uh,
00:28:34 --> 00:28:36 we've uh, done before, we did it a week
00:28:36 --> 00:28:39 ago, uh, about uh, the comet
00:28:39 --> 00:28:42 2024 yr. Uh 4. I happen to be
00:28:42 --> 00:28:45 playing our uh, podcast in the car.
00:28:45 --> 00:28:47 I always like to listen to it just to see how
00:28:47 --> 00:28:50 it sounds and you know, decide whether or not
00:28:50 --> 00:28:53 I'm doing a good job or not. Did it in radio,
00:28:53 --> 00:28:55 do it with the podcast. But I, I was picking
00:28:55 --> 00:28:58 up our grandchildren from school and
00:28:58 --> 00:29:01 uh, Nathaniel who um,
00:29:01 --> 00:29:03 is 10, uh, years old,
00:29:04 --> 00:29:06 um, he was listening and he said to me, is
00:29:07 --> 00:29:09 a comet going to hit Earth? And I
00:29:09 --> 00:29:12 had to kind of explain to him what was going
00:29:12 --> 00:29:14 on without alarming him.
00:29:15 --> 00:29:17 Uh, and now an update on the story. Last week
00:29:17 --> 00:29:20 we were saying um, there was
00:29:20 --> 00:29:23 a 70 to 77% chance of this
00:29:23 --> 00:29:26 thing, um, hitting the atmosphere in
00:29:26 --> 00:29:27 2032.
00:29:28 --> 00:29:31 Uh, sorry, yeah, see that's,
00:29:31 --> 00:29:33 that was a popular press comment. One in
00:29:33 --> 00:29:36 seven. But now that number's dropped as
00:29:36 --> 00:29:38 at now. But that could change
00:29:38 --> 00:29:39 again.
00:29:39 --> 00:29:42 Jonti Horner: Absolutely. So as of today, so when I sent
00:29:42 --> 00:29:44 you notes through yesterday, it was at 1 in
00:29:44 --> 00:29:47 43. It's now fallen back to 1 in 48.
00:29:47 --> 00:29:50 This number is changing every day. And what
00:29:50 --> 00:29:52 we will see and what we'll continue to see is
00:29:52 --> 00:29:55 most likely those odds of an impact
00:29:55 --> 00:29:58 gradually increasing until
00:29:58 --> 00:30:01 eventually they most likely drop to zero. Ah.
00:30:01 --> 00:30:03 And the reason for that is we're getting more
00:30:03 --> 00:30:05 observations with every day that passes. And
00:30:05 --> 00:30:07 so with every day that passes we get a
00:30:07 --> 00:30:09 refined estimate of the orbit of this
00:30:09 --> 00:30:12 thing. That then means that uh, the
00:30:12 --> 00:30:15 exact location of the object on 22nd of
00:30:15 --> 00:30:17 December 2032 has a smaller
00:30:17 --> 00:30:20 uncertainty. So that big area of space that
00:30:20 --> 00:30:22 we think it will be in with each day's
00:30:22 --> 00:30:25 observations get smaller and smaller. Now if
00:30:25 --> 00:30:28 the Earth is still in that area of space, the
00:30:28 --> 00:30:30 Earth is a bigger fraction of that total
00:30:30 --> 00:30:33 volume of space. And so the probability of
00:30:33 --> 00:30:35 impact is going up because we're a bigger
00:30:35 --> 00:30:37 fraction of the total area that thing could
00:30:37 --> 00:30:39 be in. But at some point, as that volume of
00:30:39 --> 00:30:42 space shrinks down, the Earth could fall out
00:30:42 --> 00:30:43 of it. And at that point, the probability
00:30:43 --> 00:30:46 immediately drops to zero. So it isn't a
00:30:46 --> 00:30:48 reason to panic at all. This is exactly the
00:30:48 --> 00:30:51 behavior you would expect to see. But
00:30:51 --> 00:30:53 that probability will continue to change day
00:30:53 --> 00:30:55 by day. It wouldn't surprise me if it keeps
00:30:55 --> 00:30:58 getting higher. Now, this asteroid we're
00:30:58 --> 00:31:00 probably going to lose track of in about
00:31:00 --> 00:31:03 April. It'll be too far away to observe, but
00:31:03 --> 00:31:05 then we won't see it again till 2028. People
00:31:05 --> 00:31:07 are digging back through archival
00:31:07 --> 00:31:10 observations from 2016,
00:31:10 --> 00:31:13 2012, 2008, because this thing comes
00:31:13 --> 00:31:14 roughly near the earth every four years or
00:31:14 --> 00:31:17 so. If we find it by chance
00:31:17 --> 00:31:19 on one photograph from one of those previous
00:31:19 --> 00:31:22 years, this probability will change
00:31:22 --> 00:31:24 dramatically and we'll probably drop to zero
00:31:24 --> 00:31:26 straight away. If not, we'll have to wait
00:31:26 --> 00:31:28 till 2028. And until then we'll see this
00:31:28 --> 00:31:31 continual slight more wobbling around as each
00:31:31 --> 00:31:32 day's observations come in and it gets
00:31:32 --> 00:31:35 recalculated. So fundamentally,
00:31:35 --> 00:31:38 nothing has changed. This thing still poses a
00:31:38 --> 00:31:40 threat. Do not panic. Even if it were to hit
00:31:40 --> 00:31:41 us, it's not really going to cause a problem
00:31:41 --> 00:31:44 anyway, to be brutally honest. But it is
00:31:44 --> 00:31:46 fascinating to watch this happen and to see
00:31:46 --> 00:31:48 that evolution in real time.
00:31:49 --> 00:31:51 Andrew Dunkley: Absolutely. Yeah. I think I said comet, I
00:31:51 --> 00:31:54 meant asteroid. But, um, yeah, 2024,
00:31:54 --> 00:31:57 uh, if you do a search on Google or
00:31:57 --> 00:31:59 whatever your favorite search engine is,
00:31:59 --> 00:32:01 you'll find plenty of information.
00:32:01 --> 00:32:04 And you. I would advise filtering the
00:32:04 --> 00:32:06 popular press comments because,
00:32:08 --> 00:32:09 uh, they've been going hammer and tongs on
00:32:09 --> 00:32:10 this one.
00:32:10 --> 00:32:11 Jonti Horner: Absolutely.
00:32:11 --> 00:32:13 Andrew Dunkley: Um, but, yeah, uh, like, uh,
00:32:13 --> 00:32:16 Jonti said on the previous story, it's
00:32:16 --> 00:32:19 clickbait, isn't it? Um, that's really
00:32:19 --> 00:32:22 it. But, uh, I did reassure my grandson
00:32:22 --> 00:32:24 because as soon as I finished explaining it,
00:32:24 --> 00:32:26 he wanted to talk about Pokemon. So I think I
00:32:26 --> 00:32:29 was successful in deflecting him there.
00:32:30 --> 00:32:33 To, uh, our final story, Jonti, and this
00:32:33 --> 00:32:34 one is about stuff that's hitting the
00:32:34 --> 00:32:37 atmosphere. We're talking specifically
00:32:37 --> 00:32:40 about the, um, turnover of
00:32:40 --> 00:32:43 SpaceX satellites. They've
00:32:43 --> 00:32:46 been starting to rain down on
00:32:46 --> 00:32:48 Earth, uh, fairly regularly. In fact, uh, the
00:32:48 --> 00:32:51 Space Nuts podcast group on
00:32:51 --> 00:32:54 Facebook has been, um, discussing
00:32:54 --> 00:32:56 this. They put an article on there that the
00:32:56 --> 00:32:59 listeners were discussing, and
00:32:59 --> 00:33:02 some were quite surprised by the kinds
00:33:02 --> 00:33:04 of numbers we're talking about. But this is
00:33:04 --> 00:33:07 just going to get more and more significant
00:33:07 --> 00:33:09 as time goes on because they haven't finished
00:33:09 --> 00:33:12 deploying their entire, uh, fleet
00:33:12 --> 00:33:14 or whatever. You want to call them of, uh,
00:33:14 --> 00:33:15 SpaceX satellites.
00:33:16 --> 00:33:19 Jonti Horner: Yeah. This is yet another multifaceted story.
00:33:19 --> 00:33:21 So I know a lot of people who get very
00:33:21 --> 00:33:23 passionate in their defense of SpaceX and
00:33:23 --> 00:33:25 Elon Musk and many others who have very
00:33:25 --> 00:33:27 negative views of them. And I always try and
00:33:27 --> 00:33:29 be somewhere in the middle. It's like
00:33:29 --> 00:33:31 in literature if you ever read a book, very
00:33:32 --> 00:33:35 few people are purely evil or purely good.
00:33:35 --> 00:33:36 Everybody's somewhere in the middle unless
00:33:36 --> 00:33:39 it's a bad book. And it's the same with
00:33:39 --> 00:33:41 things like this. There's a lot of good about
00:33:41 --> 00:33:43 this and a lot of bad about it. Now SpaceX
00:33:43 --> 00:33:46 are putting up their Starlink satellites to
00:33:46 --> 00:33:49 deliver Internet access, which is
00:33:49 --> 00:33:51 a great benefit to people in the regions.
00:33:52 --> 00:33:54 I've heard plenty of stories of people who
00:33:54 --> 00:33:56 are living remotely in Australia who can't
00:33:56 --> 00:33:57 get a good Internet connection on Starlink as
00:33:57 --> 00:33:59 been revolutionary to them.
00:33:59 --> 00:34:02 Andrew Dunkley: Yeah. And cruise ships use Starlink.
00:34:02 --> 00:34:04 Jonti Horner: Absolutely. Because they're always.
00:34:04 --> 00:34:06 Andrew Dunkley: They're in remote areas a lot.
00:34:06 --> 00:34:08 Jonti Horner: Yeah, it is a really incredible
00:34:08 --> 00:34:10 technological development. On the other hand,
00:34:10 --> 00:34:12 you've got all the concerns about the light
00:34:12 --> 00:34:14 pollution from these things and the
00:34:14 --> 00:34:16 fact that they launched them without anybody
00:34:17 --> 00:34:19 really being able to regulate it or say boot
00:34:19 --> 00:34:22 about it. It's a
00:34:22 --> 00:34:24 multifaceted problem and there's good things
00:34:24 --> 00:34:26 and bad things about it. In much the same
00:34:26 --> 00:34:29 way, this story is both a good and bad story.
00:34:29 --> 00:34:32 You've got all these satellites up there and
00:34:32 --> 00:34:35 they have finite lifetimes. They are
00:34:35 --> 00:34:37 low down because you need them to be in low
00:34:37 --> 00:34:39 Earth orbit in order to get good latency. If
00:34:39 --> 00:34:42 you put these at geostationary orbit, you've
00:34:42 --> 00:34:43 got the light travel time there and back
00:34:43 --> 00:34:46 again, you've got a long way to go and that
00:34:46 --> 00:34:48 puts a significant ping, which means for the
00:34:48 --> 00:34:50 people playing Twitch games and first person
00:34:51 --> 00:34:53 shooter games, they can't play and sulk. Um,
00:34:54 --> 00:34:56 but everybody wants a faster Internet
00:34:56 --> 00:34:57 connection with the lowest latency possible.
00:34:57 --> 00:35:00 So these things are in low Earth orbit, which
00:35:00 --> 00:35:02 means that they are moving through a
00:35:02 --> 00:35:04 significant chunk of the Earth's atmosphere.
00:35:04 --> 00:35:05 The Earth's atmosphere doesn't just stop, it
00:35:05 --> 00:35:07 just gets thinner and thinner and thinner the
00:35:07 --> 00:35:09 further you go away. Technically, the moon is
00:35:09 --> 00:35:11 still encountering bits of the Earth's
00:35:11 --> 00:35:12 atmosphere. It should by that point it's so
00:35:12 --> 00:35:15 thin as to be irrelevant. But at the altitude
00:35:15 --> 00:35:17 of these Starlink satellites, they are
00:35:17 --> 00:35:20 actually traveling into a headwind. So
00:35:20 --> 00:35:22 without something to bump them up, they would
00:35:22 --> 00:35:24 eventually come down naturally anyway. But
00:35:24 --> 00:35:27 also they are a fixed term
00:35:27 --> 00:35:29 thing. They typically, I think thinking about
00:35:29 --> 00:35:31 an individual satellite having about A five
00:35:31 --> 00:35:32 year lifetime.
00:35:32 --> 00:35:33 Andrew Dunkley: Yeah.
00:35:33 --> 00:35:35 Jonti Horner: Now it's about five years since the Starlink
00:35:35 --> 00:35:37 satellite started getting launched, which
00:35:37 --> 00:35:39 means the very first generation of them are
00:35:39 --> 00:35:41 now in their retirement phase.
00:35:42 --> 00:35:45 What is really good about this is
00:35:45 --> 00:35:48 that SpaceX and Starlink are being
00:35:48 --> 00:35:50 very aggressive in the retirement in that
00:35:50 --> 00:35:52 they are controlling these things and
00:35:52 --> 00:35:54 deliberately putting them back in the
00:35:54 --> 00:35:55 atmosphere to burn up in a controlled
00:35:55 --> 00:35:57 fashion. So they're controlling where they
00:35:57 --> 00:35:59 drop them into the atmosphere to minimize the
00:35:59 --> 00:36:02 risk to air travel and the risk of them
00:36:02 --> 00:36:05 dropping on a city and things like this. And
00:36:05 --> 00:36:07 that is really good governance. It's really
00:36:07 --> 00:36:08 important to say that there's a lot of stuff
00:36:08 --> 00:36:11 up there that will come down of its own
00:36:11 --> 00:36:13 accord, at its own time, with no control over
00:36:13 --> 00:36:16 it. And that's a risk. And people are
00:36:16 --> 00:36:17 talking about the fact that there's probably
00:36:17 --> 00:36:20 as high as a 26% chance that in a given
00:36:20 --> 00:36:23 year from now on space debris will fall
00:36:23 --> 00:36:25 through a populated airspace
00:36:26 --> 00:36:28 m which is problematic. There's even studies
00:36:28 --> 00:36:30 saying there's a 1 in 10 chance that within
00:36:30 --> 00:36:32 the next decade somebody will die as a result
00:36:32 --> 00:36:35 of space debris hitting them. So that's a
00:36:35 --> 00:36:38 concern. And by deliberately deorbiting
00:36:38 --> 00:36:40 these things in a controlled fashion, they're
00:36:40 --> 00:36:42 mitigating those risks, putting things down
00:36:42 --> 00:36:45 in a safe fashion. But because of how many
00:36:45 --> 00:36:47 satellites they're putting up there, that
00:36:47 --> 00:36:48 means we've got an increasing number of them
00:36:48 --> 00:36:51 coming back down. There are currently
00:36:51 --> 00:36:54 7 Starlink satellites up there. The
00:36:54 --> 00:36:56 goal is to get up to 42. That is their
00:36:57 --> 00:36:59 stated end. So that's the factor of six times
00:36:59 --> 00:37:00 more.
00:37:00 --> 00:37:02 Andrew Dunkley: Yeah, that's just Starlink, because there are
00:37:03 --> 00:37:03 many others.
00:37:04 --> 00:37:06 Jonti Horner: There are. If you look at all of the proposed
00:37:06 --> 00:37:08 mega constellations, I think the current
00:37:08 --> 00:37:10 number is that there could be as many as
00:37:10 --> 00:37:12 550 satellites in orbit within a decade.
00:37:12 --> 00:37:15 Which makes me, as an amateur astronomer, the
00:37:15 --> 00:37:17 kind of part of me that goes out and observes
00:37:17 --> 00:37:19 meteor showers and stuff just makes me weep
00:37:19 --> 00:37:21 because we'll lose the night sky to such a
00:37:21 --> 00:37:24 degree. But that's a slightly separate thing.
00:37:24 --> 00:37:26 With 7 up there at the minute, the
00:37:26 --> 00:37:28 retirements of those first gen ones are now
00:37:28 --> 00:37:30 coming at a rate of four or five satellites
00:37:30 --> 00:37:33 per day. So that means four or five
00:37:33 --> 00:37:35 satellites are burning up somewhere over the
00:37:35 --> 00:37:37 Earth, uh, every single day of the
00:37:38 --> 00:37:40 calendar year. That's only going to go up
00:37:40 --> 00:37:42 because if you increase the number of
00:37:42 --> 00:37:44 satellites up there by a factor of six times,
00:37:44 --> 00:37:46 then you'll increase that number of reentries
00:37:46 --> 00:37:48 per day by a factor of six times. So within
00:37:49 --> 00:37:51 five Years, we could well be looking at
00:37:52 --> 00:37:54 something nearer to 25 or even 30 satellites
00:37:54 --> 00:37:57 per day coming back into the atmosphere. Now,
00:37:57 --> 00:37:59 these are coming in in a controlled fashion.
00:37:59 --> 00:38:01 So, uh, they're trying to drop them in the
00:38:01 --> 00:38:03 atmosphere away from things that would be
00:38:03 --> 00:38:05 threatened by lumps of metal hitting the
00:38:05 --> 00:38:08 Earth's atmosphere, essentially. Yeah. But
00:38:08 --> 00:38:09 there is now a growing concern about the
00:38:09 --> 00:38:11 pollution side of this.
00:38:11 --> 00:38:13 Andrew Dunkley: That's the thing that I was getting. Yeah,
00:38:13 --> 00:38:16 that's the. That's the big if, isn't it?
00:38:16 --> 00:38:18 Jonti Horner: And it's a difficult one because it's not an
00:38:18 --> 00:38:19 experiment that's ever been done before.
00:38:19 --> 00:38:22 Things have re entered. Um, but in the past,
00:38:22 --> 00:38:24 we've not been putting much up in space. So
00:38:24 --> 00:38:26 it's been a very rare thing. A little bit of
00:38:26 --> 00:38:29 extra material dumped into the atmosphere. A
00:38:29 --> 00:38:31 tiny amount compared to the amount that comes
00:38:31 --> 00:38:34 in naturally through meteors and meteorites,
00:38:34 --> 00:38:36 um, stuff hitting the Earth's atmosphere,
00:38:36 --> 00:38:37 naturally. But we're now getting to a stage
00:38:37 --> 00:38:39 where this is a significant amount of
00:38:39 --> 00:38:41 material entering the Earth's atmosphere.
00:38:41 --> 00:38:43 Each of these Generation 1 satellites is
00:38:43 --> 00:38:45 several hundred kilos of material.
00:38:46 --> 00:38:48 So when you've got five of them coming in a
00:38:48 --> 00:38:50 day, that's a couple of tons of material
00:38:50 --> 00:38:53 being ablated and added to the atmosphere,
00:38:53 --> 00:38:56 mainly in the form of heavy metals. There
00:38:56 --> 00:38:58 is a fact that I've pulled out of an
00:38:58 --> 00:39:00 interesting article. India Today of all
00:39:00 --> 00:39:02 places, have got a fairly good article about
00:39:02 --> 00:39:04 this. And, um, one thing they point out is
00:39:04 --> 00:39:06 that each individual one of these Generation
00:39:07 --> 00:39:09 1 Starlink satellites, when it burns up in
00:39:09 --> 00:39:11 the atmosphere, when it ablates, deposits
00:39:11 --> 00:39:14 about 30 kilos of aluminum oxide
00:39:14 --> 00:39:16 into the upper atmosphere, about where the
00:39:16 --> 00:39:19 ozone layer is. Now that's a problem because
00:39:19 --> 00:39:22 aluminium oxide is a compound that is known
00:39:22 --> 00:39:25 to be very devastating to the ozone layer.
00:39:25 --> 00:39:27 It's a real problem. Now, if each satellite
00:39:27 --> 00:39:30 is dumping 30 kg into the atmosphere,
00:39:30 --> 00:39:32 that has a potential to destroy a large
00:39:32 --> 00:39:35 amount of ozone. If you're suddenly dumping
00:39:35 --> 00:39:37 five of them in per day, that's 150
00:39:37 --> 00:39:40 kilos per day. We go up
00:39:40 --> 00:39:43 to the 25. Obviously, that goes up
00:39:43 --> 00:39:45 again from 150 kilos to what, five times
00:39:45 --> 00:39:48 150, 750. 50 nil. Your
00:39:48 --> 00:39:51 ton of aluminium oxide per day.
00:39:52 --> 00:39:53 Something that can damage the ozone layer.
00:39:53 --> 00:39:55 And we've only just got out of the time where
00:39:55 --> 00:39:57 we did an incredible job of preventing us
00:39:57 --> 00:39:59 killing the ozone layer. Yeah, we're about to
00:39:59 --> 00:40:02 start it again. People have tried
00:40:02 --> 00:40:04 to do some computational studies of the
00:40:04 --> 00:40:06 effects of adding all this metal to the upper
00:40:06 --> 00:40:08 atmosphere. And, uh, nobody really knows
00:40:08 --> 00:40:10 what's going to happen? Some studies have
00:40:10 --> 00:40:13 said that it could accidentally help to
00:40:13 --> 00:40:15 slightly mitigate climate change because it
00:40:15 --> 00:40:16 might increase the albedo of the Earth's
00:40:16 --> 00:40:17 atmosphere.
00:40:17 --> 00:40:19 It might cause more clouds to form, so it
00:40:19 --> 00:40:21 could reflect a bit more sunlight or could be
00:40:21 --> 00:40:23 good. But other studies have suggested the
00:40:23 --> 00:40:24 opposite, that it could actually lower the
00:40:24 --> 00:40:27 amount of clouds we've got and also add a bit
00:40:27 --> 00:40:30 more greenhouse nastiness to the mix. So it
00:40:30 --> 00:40:31 could have an impact on our climate. We don't
00:40:31 --> 00:40:33 know which way it'll go. It could have an
00:40:33 --> 00:40:36 impact on the ozone layer. We just don't know
00:40:36 --> 00:40:38 yet. And so what's happening with this is
00:40:38 --> 00:40:40 we're effectively running a science
00:40:40 --> 00:40:42 experiment like the ones you do in the lab,
00:40:42 --> 00:40:44 the ones you do at school without ever done
00:40:44 --> 00:40:47 it, without ever having done it before. And
00:40:47 --> 00:40:49 we're running it on the planet that is our
00:40:49 --> 00:40:51 own home. Um, so I guess it's a bit like,
00:40:52 --> 00:40:54 you know, you've got two unruly toddlers
00:40:54 --> 00:40:56 running around with, um, insects, prey.
00:40:56 --> 00:40:58 Like the stuff you've got to get rid of. The
00:40:58 --> 00:41:01 mosquitoes. Yeah. Running around emptying can
00:41:01 --> 00:41:02 after can of that in your house. And you just
00:41:02 --> 00:41:04 said, yeah, well, let's do it. What's the
00:41:04 --> 00:41:05 worst that can happen? And you just don't
00:41:05 --> 00:41:06 know.
00:41:06 --> 00:41:09 Andrew Dunkley: Yeah. Uh, 42
00:41:09 --> 00:41:10 satellites, when they're ultimately all up
00:41:10 --> 00:41:13 there, coming back down into the atmosphere,
00:41:13 --> 00:41:15 will deposit 1.26 million
00:41:15 --> 00:41:18 kg of aluminium oxide.
00:41:18 --> 00:41:21 So, and that's going to be continuous
00:41:21 --> 00:41:24 because it's not just 42.
00:41:24 --> 00:41:26 Uh, as they come down, they'll replace them
00:41:26 --> 00:41:28 and add more to get to their full
00:41:28 --> 00:41:31 structure. So it'll be an ongoing
00:41:31 --> 00:41:34 thing, multiplied by however many
00:41:34 --> 00:41:36 constellations are created to do the same
00:41:36 --> 00:41:37 thing. So.
00:41:37 --> 00:41:39 Jonti Horner: But it isn't also like, that is easily
00:41:39 --> 00:41:41 recoverable. That's a lot of resources that
00:41:41 --> 00:41:42 we're just losing.
00:41:42 --> 00:41:43 Andrew Dunkley: Yeah, exactly.
00:41:43 --> 00:41:46 Jonti Horner: Um, now, I could imagine a much further
00:41:46 --> 00:41:48 future where instead of things being retired
00:41:48 --> 00:41:51 by deorbiting them, you retire them by
00:41:51 --> 00:41:53 boosting them to kind of graveyard orbits and
00:41:53 --> 00:41:55 have something there collecting them and
00:41:55 --> 00:41:57 melting them down for the materials. That's
00:41:58 --> 00:41:59 why in the future, because that will be a lot
00:41:59 --> 00:42:01 more expensive. It's cheaper at the minute m
00:42:01 --> 00:42:03 to just throw them away. I mean, we see with
00:42:04 --> 00:42:05 recycling efforts that there's not much
00:42:05 --> 00:42:08 motivation to recycle when making things from
00:42:08 --> 00:42:10 new products is still cheaper.
00:42:11 --> 00:42:13 Andrew Dunkley: Yeah, well, if they could solve the latency
00:42:13 --> 00:42:16 problem, that would maybe help cure it
00:42:16 --> 00:42:19 as well. But how do you do that? Relay
00:42:19 --> 00:42:20 stations on Earth? I don't know. I Don't
00:42:20 --> 00:42:23 know. But, uh, yeah, that's a really
00:42:23 --> 00:42:25 fascinating story. I know Fred and I have
00:42:25 --> 00:42:26 talked about it before, but it's worth
00:42:26 --> 00:42:28 revisiting. And, uh, yeah, the information
00:42:28 --> 00:42:31 just keeps evolving over time
00:42:31 --> 00:42:34 and we're not nearly at
00:42:34 --> 00:42:36 capacity yet with these constellations. If
00:42:36 --> 00:42:38 you'd like to read it, uh, as Jonti said,
00:42:38 --> 00:42:40 it's, uh, on the website India
00:42:40 --> 00:42:43 today.in that brings
00:42:43 --> 00:42:45 us to the end of the show. Don't forget to
00:42:45 --> 00:42:47 visit our website or our social media sites.
00:42:47 --> 00:42:50 Plenty of things to see and do there. Uh, if
00:42:50 --> 00:42:51 you have any thoughts on any of the things
00:42:52 --> 00:42:54 we've discussed, by all means, uh, send us a
00:42:54 --> 00:42:56 message via our website. Just, there's a
00:42:56 --> 00:42:57 little, uh, button up the top of our
00:42:57 --> 00:43:00 homepage, um, ama, where you can
00:43:00 --> 00:43:03 send us messages and audio questions or
00:43:03 --> 00:43:04 whatever you like. Uh,
00:43:04 --> 00:43:07 spacenutspodcast.com or
00:43:07 --> 00:43:10 spacenuts IO is the place to
00:43:10 --> 00:43:12 go. John D. Thank you so much. We're at the
00:43:12 --> 00:43:14 end. We'll catch up with you real soon.
00:43:14 --> 00:43:16 Jonti Horner: It's absolute pleasure. Thank you for having
00:43:16 --> 00:43:17 me.
00:43:17 --> 00:43:19 Andrew Dunkley: Uh, John D. Horner, professor of Astrophysics
00:43:19 --> 00:43:21 at the University of Southern Queensland.
00:43:21 --> 00:43:23 Thanks to Huw in the studio, who, um.
00:43:23 --> 00:43:26 Well, he couldn't be with us today because he
00:43:26 --> 00:43:28 got hit by a piece of SpaceX
00:43:28 --> 00:43:31 satellite. Uh, no. No, he
00:43:31 --> 00:43:33 didn't. Maybe he did. I don't know. I haven't
00:43:33 --> 00:43:35 seen him for ages. And from me, Andrew
00:43:35 --> 00:43:37 Dunkley, thanks very much for your company.
00:43:37 --> 00:43:39 We'll catch you on the next episode of Space
00:43:39 --> 00:43:41 Nuts. Bye for now.
00:43:42 --> 00:43:44 Voice Over Guy: You've been listening to the Space Nuts
00:43:44 --> 00:43:47 podcast, available at
00:43:47 --> 00:43:49 Apple Podcasts, Spotify,
00:43:49 --> 00:43:52 iHeartRadio or your favorite podcast
00:43:52 --> 00:43:54 player. You can also stream on
00:43:54 --> 00:43:57 demandn at bitesz.com. This has been another
00:43:57 --> 00:44:00 quality podcast production from bitesz.com