Cosmic Q&A: Light in Space, Astronaut Shielding, and Ice Giants
In this engaging Q&A edition of Space Nuts , hosts Andrew Dunkley and Professor Fred Watson tackle intriguing listener questions that delve into the mysteries of space. From the visibility of Voyager 1 in the depths of the solar system to the challenges of shielding astronauts from cosmic radiation, this episode is a treasure trove of cosmic knowledge.
Episode Highlights:
- Light in Space: Lee from New York City poses a thought-provoking question about how much light exists in space. Andrew and Fred explore the visibility of Voyager 1 and the implications of being far from the Sun, shedding light on human eye sensitivity and the ambient light from stars.
- Shielding Astronauts: Fenton from St. Paul, Minnesota, raises an important question about protecting astronauts from radiation beyond the Van Allen Belt. The hosts discuss potential technologies, including superconducting electromagnets and the surprising effectiveness of hydrogen-rich materials like water as radiation shields.
- Moon Comparisons: Robert from Vienna, Austria, wonders how our understanding of the solar system would differ if Earth had a moon like Europa or Titan, rather than our heavily cratered moon. The discussion highlights the significance of craters in understanding planetary history and the feasibility of landing on such moons.
- Ice Giants Explained: Duncan from Weymouth, UK, questions why Uranus and Neptune are termed "ice giants" instead of "rock giants." Andrew and Fred clarify the definitions and characteristics that distinguish these planets from their gas giant counterparts, emphasizing the unique atmospheric compositions.
For more Space Nuts, including our continuously updating newsfeed and to listen to all our episodes, visit our website. (https://www.spacenutspodcast.com/) Follow us on social media at SpaceNutsPod on Facebook, X, YouTube Music 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 (https://www.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.
Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support (https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support?utm_source=rss&utm_medium=rss&utm_campaign=rss) .
Episode link: https://play.headliner.app/episode/30869022?utm_source=youtube
00:00:00 --> 00:00:02 Space Nuts is taking a bit of a break at
00:00:02 --> 00:00:04 the moment. Uh Fred and I will be back
00:00:04 --> 00:00:06 uh in the not too distant future with
00:00:06 --> 00:00:08 fresh episodes. In the meantime, enjoy
00:00:08 --> 00:00:11 some of uh the key episodes that we have
00:00:11 --> 00:00:14 presented over the years, major events
00:00:14 --> 00:00:17 in astronomy and space science and we'll
00:00:17 --> 00:00:19 see you real soon.
00:00:19 --> 00:00:20 >> Space Nuts.
00:00:20 --> 00:00:23 >> Hi there. Thanks for joining us on a Q&A
00:00:23 --> 00:00:25 edition of Space Nuts. I'm Andrew
00:00:25 --> 00:00:27 Dunley, your host. Once again, uh,
00:00:27 --> 00:00:30 thanks for joining us and, um, good to
00:00:30 --> 00:00:31 have your company. On this edition,
00:00:31 --> 00:00:33 we're answering some questions about
00:00:33 --> 00:00:36 light in space. Um, this one comes from
00:00:36 --> 00:00:38 Lee. He's he's asked a very interesting
00:00:38 --> 00:00:40 question. I've never actually thought
00:00:40 --> 00:00:43 about this particular uh, concept, but
00:00:43 --> 00:00:46 uh, it's it's a question that I think is
00:00:46 --> 00:00:48 worth answering for sure. It's why we
00:00:48 --> 00:00:50 included it. Fenton wants to know about
00:00:50 --> 00:00:53 um shielding astronauts in the outer
00:00:53 --> 00:00:54 reaches of the solar system and he's got
00:00:54 --> 00:00:57 an idea on how to do that. Uh Robert
00:00:57 --> 00:01:00 wants to talk about things we learn from
00:01:00 --> 00:01:02 the moon and what if our moon wasn't the
00:01:02 --> 00:01:05 same as the moon is now. Would our
00:01:05 --> 00:01:07 learnings be different? That's a really
00:01:07 --> 00:01:09 interesting question. And Duncan wants
00:01:09 --> 00:01:11 to talk about ice giants and why are
00:01:11 --> 00:01:12 they ice giants? Why don't we call them
00:01:12 --> 00:01:14 something else? That's all coming up
00:01:14 --> 00:01:18 shortly on this edition of Space Nuts.
00:01:18 --> 00:01:23 15 seconds. Guidance is internal. 10 9
00:01:23 --> 00:01:24 Ignition sequence start.
00:01:24 --> 00:01:25 >> Space nuts.
00:01:25 --> 00:01:28 >> 5 4 3 2
00:01:28 --> 00:01:30 >> 1 2 3 4 5 5 4 3 2 1
00:01:30 --> 00:01:31 >> Space Nuts.
00:01:31 --> 00:01:34 >> Astronauts report. It feels good.
00:01:34 --> 00:01:36 >> Once again, we welcome the one and only
00:01:36 --> 00:01:39 Fred Watson, astronomer at large. Hello,
00:01:39 --> 00:01:39 Fred.
00:01:39 --> 00:01:41 >> Hello, Andrew. How have you been since
00:01:41 --> 00:01:43 we lost B?
00:01:43 --> 00:01:45 >> Um, I haven't moved from this seat in
00:01:45 --> 00:01:47 all that time.
00:01:48 --> 00:01:50 Well, it's I know it's I can see you're
00:01:50 --> 00:01:53 glued to your chair there at home.
00:01:53 --> 00:01:55 >> Very much so.
00:01:55 --> 00:01:57 >> Yes. Uh shall we get um straight into it
00:01:57 --> 00:01:59 and answer some questions from our
00:01:59 --> 00:02:01 audience?
00:02:01 --> 00:02:02 >> Uh we will.
00:02:02 --> 00:02:03 >> That's a good idea. Yeah,
00:02:03 --> 00:02:05 >> it is. That's it's what we're here for.
00:02:05 --> 00:02:07 This first one, Fred, comes from Lee. He
00:02:08 --> 00:02:11 lives in New York City. Uh he's he's
00:02:11 --> 00:02:14 asking how much light is in space. He'll
00:02:14 --> 00:02:17 qualify that question. For example, if
00:02:17 --> 00:02:19 you were to visit Voyager 1, where
00:02:19 --> 00:02:21 Voyager 1 is today, would you be able to
00:02:21 --> 00:02:24 see it? Would you see just a silhouette?
00:02:24 --> 00:02:26 Would you be able to make out details
00:02:26 --> 00:02:29 and colors if there if there are any
00:02:29 --> 00:02:32 colors on it? Uh what about if you and
00:02:32 --> 00:02:34 Voyager were midway between the sun and
00:02:34 --> 00:02:38 Alpha Centuri? Uh can we know a
00:02:38 --> 00:02:41 reasonably accurate answer or is it pure
00:02:41 --> 00:02:43 speculation? Thanks. Love the show, Lee
00:02:43 --> 00:02:45 from New York. I I've never thought
00:02:46 --> 00:02:47 about that. I mean, we take for granted
00:02:47 --> 00:02:49 light on Earth because it's, you know,
00:02:49 --> 00:02:51 we're illuminated by the sun, but it's
00:02:51 --> 00:02:53 it's a bit different in other parts of
00:02:53 --> 00:02:55 the solar system and the universe in
00:02:55 --> 00:02:57 general. So, yeah, if we could just go,
00:02:57 --> 00:02:59 "Snap, we're out there next to Voyager
00:02:59 --> 00:03:02 One, could we actually see it? Is it
00:03:02 --> 00:03:04 illuminated in any way? Is it being
00:03:04 --> 00:03:06 illuminated by something? What would it
00:03:06 --> 00:03:08 be like?"
00:03:08 --> 00:03:10 >> Uh, the answer is yes, you'd see it. Um
00:03:10 --> 00:03:14 and um so we're talking really now about
00:03:14 --> 00:03:16 the sensitivity of the human eye
00:03:16 --> 00:03:19 >> u because uh with a with a camera uh you
00:03:19 --> 00:03:22 know um with long exposure settings and
00:03:22 --> 00:03:25 things you'd be able to see in great
00:03:25 --> 00:03:28 detail but thinking about the human eye.
00:03:28 --> 00:03:31 So um
00:03:31 --> 00:03:33 I used to work as you know at Siding
00:03:33 --> 00:03:37 Spring Observatory. Uh I spent many
00:03:37 --> 00:03:41 hours uh outside at night there. It is a
00:03:41 --> 00:03:43 place that is truly dark. There's no
00:03:43 --> 00:03:46 interference from street lights. Uh
00:03:46 --> 00:03:48 there are few blobs of light on the
00:03:48 --> 00:03:50 horizon but nothing that affects the
00:03:50 --> 00:03:53 pristine darkness of the night sky. And
00:03:53 --> 00:03:55 on a starry night with the sun not in
00:03:55 --> 00:03:59 the sky, you can see quite clearly. Um
00:03:59 --> 00:04:01 there's enough light from the stars
00:04:01 --> 00:04:03 themselves to let you see where you're
00:04:03 --> 00:04:08 going. Uh let you, you know, walk around
00:04:08 --> 00:04:10 and be quite confident that you're not
00:04:10 --> 00:04:11 going to fall off the mountain as I
00:04:11 --> 00:04:14 nearly did one night when it was uh
00:04:14 --> 00:04:15 cloudy. I went out without my torch. I
00:04:16 --> 00:04:17 thought, "Oh yeah, I'll see by the
00:04:17 --> 00:04:18 stars." But fortunately unfortunately
00:04:18 --> 00:04:20 the cloud had come in. I couldn't see
00:04:20 --> 00:04:22 anything and I nearly fell fell off the
00:04:22 --> 00:04:23 mountain.
00:04:23 --> 00:04:25 >> I didn't in the end, but um
00:04:25 --> 00:04:27 >> that's a that's a long drop free.
00:04:27 --> 00:04:29 >> Yes, it is. Yes, it's quite a long drop.
00:04:29 --> 00:04:32 Anyway, uh if you uh you know, normally
00:04:32 --> 00:04:36 on a starry night you will see um by the
00:04:36 --> 00:04:39 light of the stars. Now, where Voyager
00:04:39 --> 00:04:42 is, Voyager 1, uh I just looked it up.
00:04:42 --> 00:04:47 uh it is uh at a distance from the sun
00:04:47 --> 00:04:51 in astronomical units which is 163
00:04:51 --> 00:04:55 astronomical units. That's 163 times the
00:04:55 --> 00:04:58 number of uh times the distance between
00:04:58 --> 00:05:00 the earth and the sun. So that's 150
00:05:00 --> 00:05:04 million kilometers. Multiply that by 163
00:05:04 --> 00:05:07 and you will get
00:05:07 --> 00:05:10 uh what do you get? Uh I was looking for
00:05:10 --> 00:05:12 it in kilometers but it's not there.
00:05:12 --> 00:05:13 I'll have to do the numbers. Anyway, it
00:05:13 --> 00:05:16 doesn't matter. The main thing is um its
00:05:16 --> 00:05:19 distance is 22.55 light hours away. Uh
00:05:19 --> 00:05:22 that's how long it takes uh the signal
00:05:22 --> 00:05:24 to get from Voyager to Earth. It's
00:05:24 --> 00:05:26 almost a day. It's almost a light day
00:05:26 --> 00:05:31 away. Um, so at that distance from the
00:05:31 --> 00:05:34 sun, 160 odd astronomical units, uh,
00:05:34 --> 00:05:36 there's still significant light coming
00:05:36 --> 00:05:39 from the sun, not to mention Venus,
00:05:39 --> 00:05:43 uh, and, um, you know, Jupiter and, uh,
00:05:43 --> 00:05:45 the other planets, mostly the sun,
00:05:45 --> 00:05:47 though, you you're being illuminated by
00:05:47 --> 00:05:50 the sun. So that certainly ups it, uh,
00:05:50 --> 00:05:52 as compared with just being illuminated
00:05:52 --> 00:05:54 by the starry sky, which is what I was
00:05:54 --> 00:05:56 just talking about. So you'd see it
00:05:56 --> 00:05:58 really clearly. Uh you wouldn't have any
00:05:58 --> 00:06:00 problem making it out assuming your eye
00:06:00 --> 00:06:03 was dark adapted.
00:06:03 --> 00:06:05 >> So [clears throat] it's um it's fairly
00:06:05 --> 00:06:07 bright out there. I we talked about the
00:06:07 --> 00:06:10 sensitivity of the human eye as uh you
00:06:10 --> 00:06:13 you referred to. How how small amount of
00:06:13 --> 00:06:16 light can we see as human beings?
00:06:16 --> 00:06:20 >> Um I think there were some experiments.
00:06:20 --> 00:06:23 Let me think. Was it was it one photon
00:06:23 --> 00:06:25 or one pixel like that?
00:06:25 --> 00:06:27 >> There was that's right. We might have
00:06:28 --> 00:06:29 talked about this. There were
00:06:29 --> 00:06:31 experiments done that showed that the
00:06:31 --> 00:06:33 human eye is capable of detecting single
00:06:34 --> 00:06:36 photons. Uh it was under special
00:06:36 --> 00:06:40 circumstances but uh and that is just
00:06:40 --> 00:06:43 extraordinary. Um when you think that
00:06:43 --> 00:06:45 the human eye can also cope with broad
00:06:46 --> 00:06:48 daylight that's the amazing thing about
00:06:48 --> 00:06:50 the human eye. It can, you know, it's
00:06:50 --> 00:06:54 quite happy uh to see light uh at one
00:06:54 --> 00:06:56 brightness and then a light that's only
00:06:56 --> 00:07:00 a millionth of as bright. Um it's fine.
00:07:00 --> 00:07:01 You can deal with that. And that's a
00:07:01 --> 00:07:03 combination of what's called retinal
00:07:03 --> 00:07:06 bleaching and the the iris of your eye
00:07:06 --> 00:07:08 opening and closing. It's all those
00:07:08 --> 00:07:11 things come together to give you this
00:07:11 --> 00:07:14 unbelievably versatile and sensitive
00:07:14 --> 00:07:16 tool with which we can look at the our
00:07:16 --> 00:07:19 surroundings. Whether it's uh the the
00:07:19 --> 00:07:20 rock face I'm looking at now because
00:07:20 --> 00:07:23 that's what our backyard consists of or
00:07:23 --> 00:07:25 whether it's uh you know the night sky
00:07:25 --> 00:07:28 where you're looking at faint objects uh
00:07:28 --> 00:07:31 in the sky. It's quite amazing.
00:07:31 --> 00:07:33 >> So even if you went deeper into space
00:07:33 --> 00:07:36 way beyond our solar system you you
00:07:36 --> 00:07:39 would probably still see objects that
00:07:39 --> 00:07:40 you were near.
00:07:40 --> 00:07:41 >> There'd be enough light from the stars.
00:07:41 --> 00:07:44 The Milky Way uh is is bright. Uh it
00:07:44 --> 00:07:47 would it would you know even if as as uh
00:07:47 --> 00:07:49 as Lee says even even if you were
00:07:49 --> 00:07:52 halfway between the sun and Alpha
00:07:52 --> 00:07:54 Centuri you'd still see it because of
00:07:54 --> 00:07:57 the ambient light u that's coming from
00:07:57 --> 00:07:58 from the stars.
00:07:58 --> 00:08:00 >> Yeah. And you'd still see color because
00:08:00 --> 00:08:03 that's well if it's dark enough it might
00:08:03 --> 00:08:05 turn into the grays which happen to
00:08:05 --> 00:08:06 >> That's right. Yeah. And I think that's
00:08:06 --> 00:08:08 likely I think it I don't think you
00:08:08 --> 00:08:10 would see color. um you would you would
00:08:10 --> 00:08:11 where it is now there's enough light
00:08:11 --> 00:08:13 coming from the sun that you'd see color
00:08:13 --> 00:08:15 but I think uh when you got further out
00:08:15 --> 00:08:18 you would start to just see the you know
00:08:18 --> 00:08:21 the as you said the that fit that sort
00:08:21 --> 00:08:23 of pale gray appearance where you're
00:08:23 --> 00:08:25 looking at very low light low light
00:08:25 --> 00:08:27 levels indeed where the color cells
00:08:27 --> 00:08:29 aren't receptive.
00:08:29 --> 00:08:31 >> There you go Lee. Uh the answer to your
00:08:31 --> 00:08:33 question is yes to all of the above
00:08:33 --> 00:08:35 basically. [clears throat]
00:08:35 --> 00:08:37 >> Great question. Excellent question. All
00:08:37 --> 00:08:39 right, let's move on. This is from
00:08:39 --> 00:08:40 Fenton.
00:08:40 --> 00:08:43 >> Yeah. Hello, Fred and Andrew. This is
00:08:43 --> 00:08:46 Fenton contacting you from St. Paul,
00:08:46 --> 00:08:51 Minnesota in the US. Um, I sort of have
00:08:51 --> 00:08:53 a different type of astrophysical
00:08:53 --> 00:08:58 question for you and this is on how to
00:08:58 --> 00:09:02 shield astronauts from radiation outside
00:09:02 --> 00:09:05 of the Van Allen belt. Um, I was curious
00:09:05 --> 00:09:08 if you know of any pending technologies
00:09:08 --> 00:09:11 that would allow this. Obvious choice
00:09:11 --> 00:09:14 would some people would say is lead, but
00:09:14 --> 00:09:16 I can think of several reasons why this
00:09:16 --> 00:09:19 is not a good idea. How about a
00:09:19 --> 00:09:22 miniature Van Allen belt which could
00:09:22 --> 00:09:26 surround a spacecraft? How does that
00:09:26 --> 00:09:29 sound? How could this become
00:09:29 --> 00:09:31 reality? Thank you very much. I hope you
00:09:32 --> 00:09:34 like the question. Bye now.
00:09:34 --> 00:09:36 >> Thanks, Fenton. Fenton always has these
00:09:36 --> 00:09:38 intriguing thoughts. I I've noticed in
00:09:38 --> 00:09:41 the times that we've heard from him. Um
00:09:41 --> 00:09:42 maybe we should start by explaining what
00:09:42 --> 00:09:44 the Van Allen belt is for those of us
00:09:44 --> 00:09:48 who just can't remember like me.
00:09:48 --> 00:09:54 Um it's uh so the van element bel
00:09:54 --> 00:09:57 you know the magnetic shielding around
00:09:57 --> 00:10:01 the earth uh which is uh
00:10:01 --> 00:10:03 caused by the the magnetism of the
00:10:03 --> 00:10:05 earth. It's caused by the uh the fact
00:10:05 --> 00:10:10 that we've got an iron core and uh
00:10:10 --> 00:10:11 basically it's in two parts. It's solid
00:10:11 --> 00:10:13 and liquid. So it acts like a dynamo.
00:10:13 --> 00:10:16 it's rotating and that gives us this uh
00:10:16 --> 00:10:20 exactly the protection that um that um
00:10:20 --> 00:10:23 um Fenton is talking about. Um yeah,
00:10:23 --> 00:10:26 >> I was going to refer I'm a bit annoyed
00:10:26 --> 00:10:29 actually because I've lost it. Uh there
00:10:29 --> 00:10:34 is a very nice article on uh it's
00:10:34 --> 00:10:38 actually on the um BBC's website uh
00:10:38 --> 00:10:41 their Sky at Night website. There's a
00:10:41 --> 00:10:43 lovely article on exactly this. Here it
00:10:43 --> 00:10:45 is. I found it. I hadn't lost it. How
00:10:46 --> 00:10:47 astronauts can hide from radiation on
00:10:48 --> 00:10:52 Mars and it goes into uh the exactly the
00:10:52 --> 00:10:54 problem that uh that Fenton's talking
00:10:54 --> 00:10:56 about. How do you present how do you
00:10:56 --> 00:11:00 prevent u astronauts basically becoming
00:11:00 --> 00:11:02 irradiated
00:11:02 --> 00:11:06 uh and over time it's basically lethal
00:11:06 --> 00:11:08 uh because because of the cosmic
00:11:08 --> 00:11:11 radiation that's coming down through
00:11:11 --> 00:11:16 space uh and it it does cell damage uh
00:11:16 --> 00:11:19 in your body uh and it can actually
00:11:19 --> 00:11:22 trigger cancer. So um the the whole
00:11:22 --> 00:11:27 study of this is uh or sorry the the
00:11:27 --> 00:11:29 thrust of this article BBC Sky at Night
00:11:29 --> 00:11:33 magazine uh is to discuss how you might
00:11:33 --> 00:11:35 protect astronauts uh from the
00:11:35 --> 00:11:38 radiation. Uh and that's not just on
00:11:38 --> 00:11:42 Mars but on route. Uh okay.
00:11:42 --> 00:11:46 Uh the solution that that Fenton has
00:11:46 --> 00:11:48 suggested is covered in a paragraph. I'm
00:11:48 --> 00:11:49 going to read it because we've quoted
00:11:49 --> 00:11:53 where the source is. Uh, for example,
00:11:54 --> 00:11:55 all right, let me no, let me go back a
00:11:55 --> 00:11:57 paragraph. One, one method of helping
00:11:57 --> 00:11:59 astronauts to avoid the radiation on
00:11:59 --> 00:12:03 Mars is active shielding. For example,
00:12:03 --> 00:12:05 superconducting electromagnets could be
00:12:05 --> 00:12:08 used to create a powerful magnetic field
00:12:08 --> 00:12:09 to deflect the incoming charged
00:12:09 --> 00:12:11 radiation particles away just as the
00:12:11 --> 00:12:13 Earth's field does. That's the lanel
00:12:14 --> 00:12:16 belt. The problem is that such solutions
00:12:16 --> 00:12:19 can demand a lot of power to run and the
00:12:19 --> 00:12:21 technology is a long way from being
00:12:21 --> 00:12:24 fully developed. An easier alternative
00:12:24 --> 00:12:26 is passive shielding. Simply placing a
00:12:26 --> 00:12:28 thick bulk of shielding material between
00:12:28 --> 00:12:32 the crew habitat and the sky. Uh and
00:12:32 --> 00:12:34 then they go on to consider different
00:12:34 --> 00:12:38 materials. Aluminium aka aluminum. Uh
00:12:38 --> 00:12:40 the metal that spacecraft are
00:12:40 --> 00:12:42 constructed from is actually a pretty
00:12:42 --> 00:12:45 bad radiation shield. Um, and they say
00:12:45 --> 00:12:48 when hit by an energetic cosmic ray, its
00:12:48 --> 00:12:50 atoms can shatter and fly onwards to
00:12:50 --> 00:12:53 create even more radiation particles.
00:12:53 --> 00:12:55 And Martian soil, the regalith, uh,
00:12:55 --> 00:12:57 which if you're on Mars, you might think
00:12:57 --> 00:12:59 about digging a hole there. Uh, it's got
00:13:00 --> 00:13:02 the same problem, but it's it's actually
00:13:02 --> 00:13:06 uh, you know, abundant. Um, and so you
00:13:06 --> 00:13:09 could use that to dig a pole. If you put
00:13:09 --> 00:13:12 a two to three meter layer on top of
00:13:12 --> 00:13:15 your habitat, uh then you'll you'll get
00:13:15 --> 00:13:17 some protection. But uh the thing that
00:13:18 --> 00:13:20 surprised me, Andrew, uh is once again
00:13:20 --> 00:13:23 it comes from this same article. Uh
00:13:23 --> 00:13:26 hydrogen is the best shielding material
00:13:26 --> 00:13:28 as it's light atoms. Yeah. It's light
00:13:28 --> 00:13:32 atoms. Uh and by light, I mean not
00:13:32 --> 00:13:34 heavy. Its light atoms don't create as
00:13:34 --> 00:13:37 much secondary radiation. And so tanks
00:13:37 --> 00:13:40 of rocket fuel or water, which is rich
00:13:40 --> 00:13:42 in hydrogen, placed over crew quarters
00:13:42 --> 00:13:44 could double up as effective radiation
00:13:44 --> 00:13:47 shields. I've heard that before that um
00:13:47 --> 00:13:49 you know, one way of protecting your
00:13:49 --> 00:13:51 spacecraft as it flies to Mars is put it
00:13:51 --> 00:13:53 put it in a tank of water. Uh it's the
00:13:53 --> 00:13:56 last thing you'd expect to do, but uh
00:13:56 --> 00:13:58 water is a good shielding material. And
00:13:58 --> 00:14:01 they also uh point out the alternative
00:14:01 --> 00:14:03 of hydrogen-rich plastics like
00:14:03 --> 00:14:06 polyethylene could be used to cement
00:14:06 --> 00:14:08 regalith grains together. This is on
00:14:08 --> 00:14:10 Mars and improve their shielding effect.
00:14:10 --> 00:14:13 Um so uh if you want to read more about
00:14:13 --> 00:14:15 this, it's an article that originally
00:14:15 --> 00:14:18 appeared in the August 22 2022 issue of
00:14:18 --> 00:14:21 BBC Skylight magazine and it covers
00:14:21 --> 00:14:23 pretty well most of the ideas uh that
00:14:23 --> 00:14:25 have been that have been suggested for
00:14:25 --> 00:14:27 this radiation issue. It's one that's
00:14:27 --> 00:14:29 got to, you know, it's got to find an
00:14:29 --> 00:14:32 answer soon because uh good old Elon and
00:14:32 --> 00:14:35 his Starship uh is getting nearer to
00:14:35 --> 00:14:36 thinking about going to Mars. I don't
00:14:36 --> 00:14:38 think it's ever going to happen, but um
00:14:38 --> 00:14:40 that's uh uh that's something he'll
00:14:40 --> 00:14:42 definitely be thinking about.
00:14:42 --> 00:14:44 >> Yes, indeed. Well, he's he's too busy
00:14:44 --> 00:14:45 dealing with the Australian government
00:14:45 --> 00:14:46 at the moment.
00:14:46 --> 00:14:48 >> Yes, indeed. That's that's right.
00:14:48 --> 00:14:50 >> Some of the content on Twitter that the
00:14:50 --> 00:14:53 government wants to get rid of simply
00:14:53 --> 00:14:55 because of its um volatility. But
00:14:55 --> 00:14:56 anyway, that's a different story. Uh but
00:14:56 --> 00:14:59 there plenty of water on Mars. So maybe
00:14:59 --> 00:15:01 maybe creating those water barriers is
00:15:01 --> 00:15:03 is probably the simplest thing to do.
00:15:03 --> 00:15:05 You've already got the material there
00:15:05 --> 00:15:07 >> if you've if you've landed in the right
00:15:07 --> 00:15:09 spot where you've got or whatever.
00:15:09 --> 00:15:11 >> That's the question. Yes, indeed. Well
00:15:11 --> 00:15:13 done, Fent Fenton. You you actually
00:15:13 --> 00:15:15 happened across some of the uh the
00:15:15 --> 00:15:18 answers too in uh asking your question.
00:15:18 --> 00:15:20 >> Uh this is Space Nuts. Andrew Dunley
00:15:20 --> 00:15:25 here with Professor Fred Watson.
00:15:25 --> 00:15:28 3 2 1
00:15:28 --> 00:15:31 >> space nuts. Now Fred, uh, our next
00:15:31 --> 00:15:33 question comes from Robert. Hi guys,
00:15:33 --> 00:15:35 love your show. Sorry for the long
00:15:35 --> 00:15:37 question, but feel free to paraphrase uh
00:15:37 --> 00:15:40 or shorten it. Our moon is heavily
00:15:40 --> 00:15:42 created and has given us a lot of
00:15:42 --> 00:15:44 insight into the history of the solar
00:15:44 --> 00:15:46 system and perhaps how the planets
00:15:46 --> 00:15:49 formed. But what if we had a moon like
00:15:49 --> 00:15:52 the icy moon Europa or the shrouded in
00:15:52 --> 00:15:55 haze Titan, both of which don't show
00:15:55 --> 00:15:58 immediate evidence of cratering? Would
00:15:58 --> 00:16:00 our theory about how the planets
00:16:00 --> 00:16:03 developed would be different? What other
00:16:03 --> 00:16:05 insights about our solar system would be
00:16:05 --> 00:16:08 missing or or would we be missing? And
00:16:08 --> 00:16:11 lastly, uh would we have spent uh or
00:16:11 --> 00:16:13 would we have sent people to land on
00:16:13 --> 00:16:17 such moons? I.e. Uh, would they be more
00:16:17 --> 00:16:19 dangerous for astronauts? Uh, cheers,
00:16:20 --> 00:16:22 Robert in Vienna, Austria. Wow. I don't
00:16:22 --> 00:16:23 think we've had a question from Vienna
00:16:23 --> 00:16:25 before, have we?
00:16:25 --> 00:16:27 >> Lovely to hear from you, Robert.
00:16:27 --> 00:16:28 >> I think I think Robert might have been
00:16:28 --> 00:16:30 in touch once before. I can't
00:16:30 --> 00:16:32 >> Oh, I might have been too.
00:16:32 --> 00:16:34 And here from Vienna. Yeah, I was in
00:16:34 --> 00:16:36 Vienna at the beginning of last year and
00:16:36 --> 00:16:37 I think I think we got something around
00:16:37 --> 00:16:40 about the same time and I was waxing
00:16:40 --> 00:16:42 lyrical about being in Vienna at the UN
00:16:42 --> 00:16:45 when I was at the Copas meeting. Anyway,
00:16:45 --> 00:16:47 uh that's another another issue. Uh what
00:16:48 --> 00:16:49 if we had a Yeah, it's a really
00:16:49 --> 00:16:53 interesting question. Um, what would we
00:16:53 --> 00:16:57 not know about the solar system if our
00:16:57 --> 00:17:01 moon was basically uh one that had been
00:17:01 --> 00:17:05 resurfaced in recent years or millennia
00:17:05 --> 00:17:07 because that's what makes a surface
00:17:07 --> 00:17:10 smooth. That's how we recognize
00:17:10 --> 00:17:13 um the fact that the universe sorry that
00:17:13 --> 00:17:15 the
00:17:15 --> 00:17:17 it's how we recognize the age of a
00:17:17 --> 00:17:19 surface is by how many craters it's got.
00:17:19 --> 00:17:21 The old the older the surface, the more
00:17:21 --> 00:17:24 craters it has. And so the moon's south
00:17:24 --> 00:17:26 southern region, which is heavily
00:17:26 --> 00:17:29 cratered, as is the backside, uh tell us
00:17:29 --> 00:17:31 that uh early on in the solar systems
00:17:31 --> 00:17:34 history, it was a very wild and woolly
00:17:34 --> 00:17:36 place with things charging about all
00:17:36 --> 00:17:38 over and causing these craters. Now, if
00:17:38 --> 00:17:40 we had a moon that was like Europa that
00:17:40 --> 00:17:45 um had, you know, icy geysers on it that
00:17:45 --> 00:17:47 basically covered up the craters, would
00:17:47 --> 00:17:50 we have known about that? My guess is
00:17:50 --> 00:17:52 yes, we would because we'd see other
00:17:52 --> 00:17:55 bodies within the solar system uh like
00:17:55 --> 00:17:59 you know other moons like um places like
00:17:59 --> 00:18:02 um um series the the biggest of the
00:18:02 --> 00:18:03 asteroids the dwarf planet that
00:18:04 --> 00:18:05 dominates the asteroid belt that's
00:18:05 --> 00:18:08 heavily created. Uh parts of Pluto are
00:18:08 --> 00:18:12 heavily crated. Um
00:18:12 --> 00:18:15 Mimas uh one of Saturn's moon is moons
00:18:15 --> 00:18:18 is heavily created too. So, so we we'd
00:18:18 --> 00:18:19 know about it by looking at other
00:18:19 --> 00:18:23 objects even if our own moon was uh
00:18:23 --> 00:18:26 smoothly surfaced. Um it's it's a but
00:18:26 --> 00:18:30 the Robert's last point uh on this uh
00:18:30 --> 00:18:33 would we have sent people to land on
00:18:33 --> 00:18:37 such a moon? Uh I think um I don't know
00:18:37 --> 00:18:38 that's a really good question. I mean we
00:18:38 --> 00:18:40 have sent people to land on our moon as
00:18:40 --> 00:18:44 it stands uh with an ancient surface. In
00:18:44 --> 00:18:47 fact, where they landed were more recent
00:18:47 --> 00:18:49 uh than the heavily cratered surfaces
00:18:49 --> 00:18:50 because they were principally in the
00:18:50 --> 00:18:52 Maria, the the basalt planes.
00:18:52 --> 00:18:53 >> Yeah.
00:18:53 --> 00:18:57 >> So maybe that suggests that we would
00:18:57 --> 00:18:59 have landed people on Europa as well. Uh
00:18:59 --> 00:19:00 because
00:19:00 --> 00:19:02 >> I think we pro Yeah, we probably would
00:19:02 --> 00:19:05 because it would have a solid surface.
00:19:05 --> 00:19:07 There'd be places because it would be so
00:19:07 --> 00:19:09 close to us, we'd be able to examine and
00:19:09 --> 00:19:12 and find the the right landing points.
00:19:12 --> 00:19:14 might be a bit more difficult with a
00:19:14 --> 00:19:18 moon that's shrouded in land gas.
00:19:18 --> 00:19:19 >> Yeah. Yeah.
00:19:19 --> 00:19:21 >> Yeah, that's right. Uh and especially um
00:19:21 --> 00:19:25 place like Titan. Uh
00:19:25 --> 00:19:27 I I still think we'd have done it.
00:19:27 --> 00:19:30 Actually, I think um you know the JFK's
00:19:30 --> 00:19:33 uh promise to put astronauts on the moon
00:19:33 --> 00:19:35 would have still held good even if it
00:19:35 --> 00:19:36 had been a very different place. If it
00:19:36 --> 00:19:39 had been like Io, uh, it might have been
00:19:39 --> 00:19:41 a different story where, you know,
00:19:41 --> 00:19:43 you've got the most volcanically active
00:19:43 --> 00:19:45 body in the entire solar system with
00:19:45 --> 00:19:47 stuff going off all over the place. I
00:19:47 --> 00:19:48 think we might have been a bit more
00:19:48 --> 00:19:51 reluctant to to land on a Yes, possibly.
00:19:51 --> 00:19:54 So, uh, it would be interesting to have
00:19:54 --> 00:19:55 something different, but then if we'd
00:19:55 --> 00:19:57 always had if if we'd always had an ice
00:19:58 --> 00:20:00 moon, we probably would have caught a
00:20:00 --> 00:20:03 question from Robert asking, "What if we
00:20:03 --> 00:20:07 had a rocky moon?" Now, would we Would
00:20:07 --> 00:20:09 we have a different interpretation of
00:20:09 --> 00:20:11 four masses of planets if there was a
00:20:11 --> 00:20:12 rocky moon next to us instead of an ice
00:20:12 --> 00:20:15 moon? Yes. Um, in an alternative
00:20:15 --> 00:20:16 universe, Robert, you would have flipped
00:20:16 --> 00:20:18 your question. Good to hear from you.
00:20:18 --> 00:20:21 Hope all all is well in Austria. Our
00:20:21 --> 00:20:23 final question for this episode comes
00:20:23 --> 00:20:25 from Duncan.
00:20:25 --> 00:20:29 >> Hello. Duncan here from Wayouth in the
00:20:29 --> 00:20:34 UK. Again, a quick question.
00:20:34 --> 00:20:36 just looking was just doing some reading
00:20:36 --> 00:20:39 and I noticed that Uranus and Neptune
00:20:39 --> 00:20:44 are often referred to as ice giants.
00:20:44 --> 00:20:48 Now, given that ice is basically just
00:20:48 --> 00:20:53 sort of like a rock form of water or CO2
00:20:53 --> 00:20:56 or whatever else, but basically just a
00:20:56 --> 00:20:59 solid form of it. Why are they not just
00:20:59 --> 00:21:03 called rock giants? Why do we make the
00:21:03 --> 00:21:05 definition of ice rather than just
00:21:05 --> 00:21:08 calling them rock? It just seems odd
00:21:08 --> 00:21:11 because the little planets in the inner
00:21:11 --> 00:21:13 solar system are referred to as rocky
00:21:13 --> 00:21:17 planets. So given that they're also
00:21:17 --> 00:21:19 apparently rocky, why are they not
00:21:19 --> 00:21:21 called rocky giants?
00:21:21 --> 00:21:26 Okay, thank you. Bye. Thanks Duncan.
00:21:26 --> 00:21:28 Appreciate your questions as always. Uh
00:21:28 --> 00:21:30 yeah. Why do we call them ice giants
00:21:30 --> 00:21:32 just for the sake of the exercise? Cuz
00:21:32 --> 00:21:36 there's gas giants and ice giants.
00:21:36 --> 00:21:38 >> Yeah, except one is a subset of the
00:21:38 --> 00:21:42 other. And so all four of the outer
00:21:42 --> 00:21:44 planets, Jupiter, Saturn, Neptune,
00:21:44 --> 00:21:46 sorry, Uranus, and Neptune, they're all
00:21:46 --> 00:21:51 gas giants because they have uh eye mass
00:21:51 --> 00:21:55 uh um you know, much more in the case of
00:21:55 --> 00:21:57 Jupiter certainly than uh than our own
00:21:57 --> 00:22:01 planet. Um the they've got they're
00:22:01 --> 00:22:03 giants. They're big. They've got high
00:22:03 --> 00:22:07 mass. Uh and they don't have a visible
00:22:07 --> 00:22:09 surface, which is why they're called gas
00:22:09 --> 00:22:11 giants because all we see is a gasy
00:22:11 --> 00:22:15 envelope. Um just to go to the last of
00:22:15 --> 00:22:17 Duncan's questions there, we we wouldn't
00:22:17 --> 00:22:19 call the inner planets rocky giants
00:22:20 --> 00:22:21 because they're not giants. They're kind
00:22:21 --> 00:22:23 of normal planet size. You know, if you
00:22:23 --> 00:22:25 if you think of the Earth as being your
00:22:25 --> 00:22:28 standard planet, then uh Mercury, Venus,
00:22:28 --> 00:22:32 and Mars are similar in size. They're
00:22:32 --> 00:22:33 all smaller. Venus is about the same
00:22:34 --> 00:22:35 size, but Mercury and Mars, of course,
00:22:35 --> 00:22:38 are smaller. So, uh so it's only when
00:22:38 --> 00:22:40 you compare with the size of Earth that
00:22:40 --> 00:22:42 you'd start talking about giants because
00:22:42 --> 00:22:44 they are much much bigger than Earth.
00:22:44 --> 00:22:47 And so, that's the gas giants. So, why
00:22:47 --> 00:22:50 are Uranus and Neptune called ice
00:22:50 --> 00:22:55 giants? because they have hazes of ice
00:22:55 --> 00:22:57 in their atmosphere.
00:22:57 --> 00:23:00 >> So, uh, and that's the the trick. It's
00:23:00 --> 00:23:02 not a solid surface. It's not rock.
00:23:02 --> 00:23:04 [snorts] It's it's a haze. It's kind of
00:23:04 --> 00:23:07 like a a dust of ice which permeates
00:23:08 --> 00:23:10 their atmosphere. And and and it's water
00:23:10 --> 00:23:14 ice in fact, uh, mostly. Uh so that's
00:23:14 --> 00:23:15 why they're called ice giants because
00:23:16 --> 00:23:19 unlike Saturn and Jupiter uh which don't
00:23:19 --> 00:23:21 have these hazes uh the the outer the
00:23:21 --> 00:23:25 rocky rock sorry the two outer planets
00:23:25 --> 00:23:27 Uranus and Neptune do they have ice
00:23:27 --> 00:23:29 hazes in their atmosphere hence the
00:23:29 --> 00:23:30 name.
00:23:30 --> 00:23:33 Okay. Yeah. And because last episode we
00:23:33 --> 00:23:35 learned there wasn't much water in
00:23:35 --> 00:23:37 Jupiter's
00:23:37 --> 00:23:41 >> in the in the two outer gas giants.
00:23:41 --> 00:23:42 Yeah. It sounds like there is. Is that
00:23:42 --> 00:23:46 why they're a different color? Yes. Yes,
00:23:46 --> 00:23:48 I think that's right. They're um and and
00:23:48 --> 00:23:49 also their their atmospheric
00:23:49 --> 00:23:51 constituents are are different. They
00:23:52 --> 00:23:53 don't have the same belt structure that
00:23:53 --> 00:23:56 Saturn and Jupiter do. Uh it may be that
00:23:56 --> 00:23:58 that's because any belts that exist are
00:23:58 --> 00:24:00 much lower in the atmosphere and so you
00:24:00 --> 00:24:03 don't see them. Um yeah, I mean uh
00:24:03 --> 00:24:08 there's there's a strong body of uh of
00:24:08 --> 00:24:11 advocacy within the space fraternity to
00:24:11 --> 00:24:16 get get more spacecraft out to Uranus
00:24:16 --> 00:24:19 and Neptune cuz they're the two planets
00:24:19 --> 00:24:22 about which we know least. Um and uh
00:24:22 --> 00:24:24 will be good to know more.
00:24:24 --> 00:24:27 >> Yeah. Well, if you sit down in snow for
00:24:27 --> 00:24:29 long enough, your Uranus turns into a
00:24:29 --> 00:24:32 nice giant sun.
00:24:32 --> 00:24:36 I couldn't help it. Sorry. Uh, yeah.
00:24:36 --> 00:24:38 >> Which is why we call it Uranus in
00:24:38 --> 00:24:39 politics.
00:24:39 --> 00:24:41 >> I know. I know.
00:24:41 --> 00:24:43 >> Yeah. But it's just a joke you've got to
00:24:43 --> 00:24:46 tell. It's just you have to.
00:24:46 --> 00:24:49 >> Yes. I blame Johannes Borda, who is the
00:24:49 --> 00:24:52 person who chose the name. It's fine in
00:24:52 --> 00:24:54 German. Uess. Uess. There's nothing
00:24:54 --> 00:24:57 wrong with that. It's great. Yeah. Ruins
00:24:57 --> 00:24:59 all the jokes, bro.
00:24:59 --> 00:25:01 >> All right. So, yes, they're ice giants
00:25:01 --> 00:25:03 for a very good reason, Duncan, because
00:25:03 --> 00:25:05 they've got ice in them uh in the
00:25:05 --> 00:25:07 atmosphere. But technically speaking,
00:25:07 --> 00:25:09 they are in fact gas giants. But
00:25:09 --> 00:25:11 >> yes, we differentiate them because of
00:25:11 --> 00:25:13 their substantially different
00:25:13 --> 00:25:15 atmospheres. There you are. Thanks,
00:25:15 --> 00:25:17 Duncan. Great to hear from you. Great to
00:25:17 --> 00:25:18 hear from everybody. Thanks for sending
00:25:18 --> 00:25:20 in your questions. Don't forget you can
00:25:20 --> 00:25:21 send in questions via our website
00:25:21 --> 00:25:23 spacenutpodcast.com
00:25:24 --> 00:25:25 spacenuts.io
00:25:25 --> 00:25:27 and all you have to do is click on the
00:25:27 --> 00:25:28 various links on the right hand side.
00:25:28 --> 00:25:30 Send us your question. That's audio
00:25:30 --> 00:25:32 questions only. Uh or you can send us
00:25:32 --> 00:25:35 text and audio questions via the AMA tab
00:25:35 --> 00:25:37 up the top. It's your choice. Don't
00:25:37 --> 00:25:38 forget to tell us who you are and where
00:25:38 --> 00:25:39 you're from and have a look around while
00:25:40 --> 00:25:42 you're on our website or join our media
00:25:42 --> 00:25:44 uh social media platforms, Facebook,
00:25:44 --> 00:25:46 Instagram, YouTube, where you can
00:25:46 --> 00:25:49 subscribe just by pressing the subscribe
00:25:49 --> 00:25:52 button below which yes, it's down there
00:25:52 --> 00:25:55 somewhere. I don't know, one of those
00:25:55 --> 00:25:57 places. Uh Fred, as always, thank you so
00:25:57 --> 00:26:00 much. Pleasure, Andrew. See you soon.
00:26:00 --> 00:26:02 >> Okay, Fred Watson, astronomer at large.
00:26:02 --> 00:26:04 We'll catch him on the next episode of
00:26:04 --> 00:26:06 Space Nuts. might catch Hugh then as
00:26:06 --> 00:26:09 well because um
00:26:09 --> 00:26:11 not here today. Didn't even call in
00:26:11 --> 00:26:13 sick. I need a note. And from me, Andrew
00:26:13 --> 00:26:15 Dumprey, thanks very much for your
00:26:15 --> 00:26:17 company. We'll see you again soon on the
00:26:17 --> 00:26:19 next episode of Space Nuts. Bye-bye.
00:26:19 --> 00:26:20 >> Space Nuts.
00:26:20 --> 00:26:22 >> You'll be listening to the Space Nuts
00:26:22 --> 00:26:25 podcast
00:26:25 --> 00:26:28 >> available at Apple Podcasts, Spotify,
00:26:28 --> 00:26:30 iHeart Radio, [music] or your favorite
00:26:30 --> 00:26:32 podcast player. You can also stream on
00:26:32 --> 00:26:35 demand at byes.com. This has been
00:26:35 --> 00:26:36 another quality podcast production
00:26:36 --> 00:26:40 [music] from sites.com.