Space Light, Cosmic Shields & Moon Mysteries | Space Nuts: Astronomy Insights & Cosmic Discoveries

WEBVTT
Kind: captions
Language: en

00:00:00.240 --> 00:00:02.389
Space Nuts is taking a bit of a break at


00:00:02.399 --> 00:00:04.630
the moment. Uh Fred and I will be back


00:00:04.640 --> 00:00:06.630
uh in the not too distant future with


00:00:06.640 --> 00:00:08.710
fresh episodes. In the meantime, enjoy


00:00:08.720 --> 00:00:11.589
some of uh the key episodes that we have


00:00:11.599 --> 00:00:14.390
presented over the years, major events


00:00:14.400 --> 00:00:17.830
in astronomy and space science and we'll


00:00:17.840 --> 00:00:19.349
see you real soon.


00:00:19.359 --> 00:00:20.470
>> Space Nuts.


00:00:20.480 --> 00:00:23.029
>> Hi there. Thanks for joining us on a Q&A


00:00:23.039 --> 00:00:25.509
edition of Space Nuts. I'm Andrew


00:00:25.519 --> 00:00:27.750
Dunley, your host. Once again, uh,


00:00:27.760 --> 00:00:30.150
thanks for joining us and, um, good to


00:00:30.160 --> 00:00:31.750
have your company. On this edition,


00:00:31.760 --> 00:00:33.670
we're answering some questions about


00:00:33.680 --> 00:00:36.790
light in space. Um, this one comes from


00:00:36.800 --> 00:00:38.630
Lee. He's he's asked a very interesting


00:00:38.640 --> 00:00:40.150
question. I've never actually thought


00:00:40.160 --> 00:00:43.270
about this particular uh, concept, but


00:00:43.280 --> 00:00:46.310
uh, it's it's a question that I think is


00:00:46.320 --> 00:00:48.150
worth answering for sure. It's why we


00:00:48.160 --> 00:00:50.389
included it. Fenton wants to know about


00:00:50.399 --> 00:00:53.270
um shielding astronauts in the outer


00:00:53.280 --> 00:00:54.790
reaches of the solar system and he's got


00:00:54.800 --> 00:00:57.830
an idea on how to do that. Uh Robert


00:00:57.840 --> 00:01:00.229
wants to talk about things we learn from


00:01:00.239 --> 00:01:02.389
the moon and what if our moon wasn't the


00:01:02.399 --> 00:01:05.189
same as the moon is now. Would our


00:01:05.199 --> 00:01:07.190
learnings be different? That's a really


00:01:07.200 --> 00:01:09.109
interesting question. And Duncan wants


00:01:09.119 --> 00:01:11.270
to talk about ice giants and why are


00:01:11.280 --> 00:01:12.870
they ice giants? Why don't we call them


00:01:12.880 --> 00:01:14.630
something else? That's all coming up


00:01:14.640 --> 00:01:18.310
shortly on this edition of Space Nuts.


00:01:18.320 --> 00:01:23.109
15 seconds. Guidance is internal. 10 9


00:01:23.119 --> 00:01:24.870
Ignition sequence start.


00:01:24.880 --> 00:01:25.830
>> Space nuts.


00:01:25.840 --> 00:01:28.390
>> 5 4 3 2


00:01:28.400 --> 00:01:30.789
>> 1 2 3 4 5 5 4 3 2 1


00:01:30.799 --> 00:01:31.910
>> Space Nuts.


00:01:31.920 --> 00:01:34.469
>> Astronauts report. It feels good.


00:01:34.479 --> 00:01:36.789
>> Once again, we welcome the one and only


00:01:36.799 --> 00:01:39.270
Fred Watson, astronomer at large. Hello,


00:01:39.280 --> 00:01:39.910
Fred.


00:01:39.920 --> 00:01:41.749
>> Hello, Andrew. How have you been since


00:01:41.759 --> 00:01:43.350
we lost B?


00:01:43.360 --> 00:01:45.910
>> Um, I haven't moved from this seat in


00:01:45.920 --> 00:01:47.990
all that time.


00:01:48.000 --> 00:01:50.469
Well, it's I know it's I can see you're


00:01:50.479 --> 00:01:53.510
glued to your chair there at home.


00:01:53.520 --> 00:01:55.190
>> Very much so.


00:01:55.200 --> 00:01:57.749
>> Yes. Uh shall we get um straight into it


00:01:57.759 --> 00:01:59.670
and answer some questions from our


00:01:59.680 --> 00:02:01.109
audience?


00:02:01.119 --> 00:02:02.310
>> Uh we will.


00:02:02.320 --> 00:02:03.590
>> That's a good idea. Yeah,


00:02:03.600 --> 00:02:05.670
>> it is. That's it's what we're here for.


00:02:05.680 --> 00:02:07.990
This first one, Fred, comes from Lee. He


00:02:08.000 --> 00:02:11.029
lives in New York City. Uh he's he's


00:02:11.039 --> 00:02:14.710
asking how much light is in space. He'll


00:02:14.720 --> 00:02:17.110
qualify that question. For example, if


00:02:17.120 --> 00:02:19.190
you were to visit Voyager 1, where


00:02:19.200 --> 00:02:21.589
Voyager 1 is today, would you be able to


00:02:21.599 --> 00:02:24.790
see it? Would you see just a silhouette?


00:02:24.800 --> 00:02:26.630
Would you be able to make out details


00:02:26.640 --> 00:02:29.430
and colors if there if there are any


00:02:29.440 --> 00:02:32.390
colors on it? Uh what about if you and


00:02:32.400 --> 00:02:34.630
Voyager were midway between the sun and


00:02:34.640 --> 00:02:38.390
Alpha Centuri? Uh can we know a


00:02:38.400 --> 00:02:41.110
reasonably accurate answer or is it pure


00:02:41.120 --> 00:02:43.589
speculation? Thanks. Love the show, Lee


00:02:43.599 --> 00:02:45.990
from New York. I I've never thought


00:02:46.000 --> 00:02:47.589
about that. I mean, we take for granted


00:02:47.599 --> 00:02:49.190
light on Earth because it's, you know,


00:02:49.200 --> 00:02:51.350
we're illuminated by the sun, but it's


00:02:51.360 --> 00:02:53.430
it's a bit different in other parts of


00:02:53.440 --> 00:02:55.350
the solar system and the universe in


00:02:55.360 --> 00:02:57.350
general. So, yeah, if we could just go,


00:02:57.360 --> 00:02:59.750
"Snap, we're out there next to Voyager


00:02:59.760 --> 00:03:02.229
One, could we actually see it? Is it


00:03:02.239 --> 00:03:04.390
illuminated in any way? Is it being


00:03:04.400 --> 00:03:06.710
illuminated by something? What would it


00:03:06.720 --> 00:03:08.390
be like?"


00:03:08.400 --> 00:03:10.869
>> Uh, the answer is yes, you'd see it. Um


00:03:10.879 --> 00:03:14.070
and um so we're talking really now about


00:03:14.080 --> 00:03:16.550
the sensitivity of the human eye


00:03:16.560 --> 00:03:19.910
>> u because uh with a with a camera uh you


00:03:19.920 --> 00:03:22.710
know um with long exposure settings and


00:03:22.720 --> 00:03:25.110
things you'd be able to see in great


00:03:25.120 --> 00:03:28.309
detail but thinking about the human eye.


00:03:28.319 --> 00:03:31.750
So um


00:03:31.760 --> 00:03:33.750
I used to work as you know at Siding


00:03:33.760 --> 00:03:37.350
Spring Observatory. Uh I spent many


00:03:37.360 --> 00:03:41.030
hours uh outside at night there. It is a


00:03:41.040 --> 00:03:43.509
place that is truly dark. There's no


00:03:43.519 --> 00:03:46.630
interference from street lights. Uh


00:03:46.640 --> 00:03:48.390
there are few blobs of light on the


00:03:48.400 --> 00:03:50.149
horizon but nothing that affects the


00:03:50.159 --> 00:03:53.670
pristine darkness of the night sky. And


00:03:53.680 --> 00:03:55.910
on a starry night with the sun not in


00:03:55.920 --> 00:03:59.429
the sky, you can see quite clearly. Um


00:03:59.439 --> 00:04:01.190
there's enough light from the stars


00:04:01.200 --> 00:04:03.910
themselves to let you see where you're


00:04:03.920 --> 00:04:08.149
going. Uh let you, you know, walk around


00:04:08.159 --> 00:04:10.070
and be quite confident that you're not


00:04:10.080 --> 00:04:11.750
going to fall off the mountain as I


00:04:11.760 --> 00:04:14.070
nearly did one night when it was uh


00:04:14.080 --> 00:04:15.990
cloudy. I went out without my torch. I


00:04:16.000 --> 00:04:17.030
thought, "Oh yeah, I'll see by the


00:04:17.040 --> 00:04:18.870
stars." But fortunately unfortunately


00:04:18.880 --> 00:04:20.390
the cloud had come in. I couldn't see


00:04:20.400 --> 00:04:22.310
anything and I nearly fell fell off the


00:04:22.320 --> 00:04:23.749
mountain.


00:04:23.759 --> 00:04:25.510
>> I didn't in the end, but um


00:04:25.520 --> 00:04:27.670
>> that's a that's a long drop free.


00:04:27.680 --> 00:04:29.430
>> Yes, it is. Yes, it's quite a long drop.


00:04:29.440 --> 00:04:32.550
Anyway, uh if you uh you know, normally


00:04:32.560 --> 00:04:36.710
on a starry night you will see um by the


00:04:36.720 --> 00:04:39.270
light of the stars. Now, where Voyager


00:04:39.280 --> 00:04:42.550
is, Voyager 1, uh I just looked it up.


00:04:42.560 --> 00:04:47.110
uh it is uh at a distance from the sun


00:04:47.120 --> 00:04:51.110
in astronomical units which is 163


00:04:51.120 --> 00:04:55.350
astronomical units. That's 163 times the


00:04:55.360 --> 00:04:58.150
number of uh times the distance between


00:04:58.160 --> 00:05:00.950
the earth and the sun. So that's 150


00:05:00.960 --> 00:05:04.469
million kilometers. Multiply that by 163


00:05:04.479 --> 00:05:07.830
and you will get


00:05:07.840 --> 00:05:10.150
uh what do you get? Uh I was looking for


00:05:10.160 --> 00:05:12.070
it in kilometers but it's not there.


00:05:12.080 --> 00:05:13.670
I'll have to do the numbers. Anyway, it


00:05:13.680 --> 00:05:16.150
doesn't matter. The main thing is um its


00:05:16.160 --> 00:05:19.749
distance is 22.55 light hours away. Uh


00:05:19.759 --> 00:05:22.150
that's how long it takes uh the signal


00:05:22.160 --> 00:05:24.469
to get from Voyager to Earth. It's


00:05:24.479 --> 00:05:26.469
almost a day. It's almost a light day


00:05:26.479 --> 00:05:31.029
away. Um, so at that distance from the


00:05:31.039 --> 00:05:34.310
sun, 160 odd astronomical units, uh,


00:05:34.320 --> 00:05:36.310
there's still significant light coming


00:05:36.320 --> 00:05:39.909
from the sun, not to mention Venus,


00:05:39.919 --> 00:05:43.270
uh, and, um, you know, Jupiter and, uh,


00:05:43.280 --> 00:05:45.270
the other planets, mostly the sun,


00:05:45.280 --> 00:05:47.590
though, you you're being illuminated by


00:05:47.600 --> 00:05:50.390
the sun. So that certainly ups it, uh,


00:05:50.400 --> 00:05:52.629
as compared with just being illuminated


00:05:52.639 --> 00:05:54.790
by the starry sky, which is what I was


00:05:54.800 --> 00:05:56.230
just talking about. So you'd see it


00:05:56.240 --> 00:05:58.070
really clearly. Uh you wouldn't have any


00:05:58.080 --> 00:06:00.230
problem making it out assuming your eye


00:06:00.240 --> 00:06:03.350
was dark adapted.


00:06:03.360 --> 00:06:05.749
>> So [clears throat] it's um it's fairly


00:06:05.759 --> 00:06:07.830
bright out there. I we talked about the


00:06:07.840 --> 00:06:10.390
sensitivity of the human eye as uh you


00:06:10.400 --> 00:06:13.590
you referred to. How how small amount of


00:06:13.600 --> 00:06:16.790
light can we see as human beings?


00:06:16.800 --> 00:06:20.469
>> Um I think there were some experiments.


00:06:20.479 --> 00:06:23.510
Let me think. Was it was it one photon


00:06:23.520 --> 00:06:25.510
or one pixel like that?


00:06:25.520 --> 00:06:27.990
>> There was that's right. We might have


00:06:28.000 --> 00:06:29.029
talked about this. There were


00:06:29.039 --> 00:06:31.510
experiments done that showed that the


00:06:31.520 --> 00:06:33.990
human eye is capable of detecting single


00:06:34.000 --> 00:06:36.950
photons. Uh it was under special


00:06:36.960 --> 00:06:40.309
circumstances but uh and that is just


00:06:40.319 --> 00:06:43.110
extraordinary. Um when you think that


00:06:43.120 --> 00:06:45.990
the human eye can also cope with broad


00:06:46.000 --> 00:06:48.390
daylight that's the amazing thing about


00:06:48.400 --> 00:06:50.550
the human eye. It can, you know, it's


00:06:50.560 --> 00:06:54.950
quite happy uh to see light uh at one


00:06:54.960 --> 00:06:56.950
brightness and then a light that's only


00:06:56.960 --> 00:07:00.150
a millionth of as bright. Um it's fine.


00:07:00.160 --> 00:07:01.909
You can deal with that. And that's a


00:07:01.919 --> 00:07:03.909
combination of what's called retinal


00:07:03.919 --> 00:07:06.870
bleaching and the the iris of your eye


00:07:06.880 --> 00:07:08.550
opening and closing. It's all those


00:07:08.560 --> 00:07:11.189
things come together to give you this


00:07:11.199 --> 00:07:14.070
unbelievably versatile and sensitive


00:07:14.080 --> 00:07:16.950
tool with which we can look at the our


00:07:16.960 --> 00:07:19.270
surroundings. Whether it's uh the the


00:07:19.280 --> 00:07:20.950
rock face I'm looking at now because


00:07:20.960 --> 00:07:23.909
that's what our backyard consists of or


00:07:23.919 --> 00:07:25.749
whether it's uh you know the night sky


00:07:25.759 --> 00:07:28.309
where you're looking at faint objects uh


00:07:28.319 --> 00:07:31.270
in the sky. It's quite amazing.


00:07:31.280 --> 00:07:33.749
>> So even if you went deeper into space


00:07:33.759 --> 00:07:36.390
way beyond our solar system you you


00:07:36.400 --> 00:07:39.189
would probably still see objects that


00:07:39.199 --> 00:07:40.230
you were near.


00:07:40.240 --> 00:07:41.670
>> There'd be enough light from the stars.


00:07:41.680 --> 00:07:44.710
The Milky Way uh is is bright. Uh it


00:07:44.720 --> 00:07:47.830
would it would you know even if as as uh


00:07:47.840 --> 00:07:49.510
as Lee says even even if you were


00:07:49.520 --> 00:07:52.150
halfway between the sun and Alpha


00:07:52.160 --> 00:07:54.070
Centuri you'd still see it because of


00:07:54.080 --> 00:07:57.430
the ambient light u that's coming from


00:07:57.440 --> 00:07:58.869
from the stars.


00:07:58.879 --> 00:08:00.950
>> Yeah. And you'd still see color because


00:08:00.960 --> 00:08:03.189
that's well if it's dark enough it might


00:08:03.199 --> 00:08:05.029
turn into the grays which happen to


00:08:05.039 --> 00:08:06.550
>> That's right. Yeah. And I think that's


00:08:06.560 --> 00:08:08.150
likely I think it I don't think you


00:08:08.160 --> 00:08:10.469
would see color. um you would you would


00:08:10.479 --> 00:08:11.830
where it is now there's enough light


00:08:11.840 --> 00:08:13.430
coming from the sun that you'd see color


00:08:13.440 --> 00:08:15.909
but I think uh when you got further out


00:08:15.919 --> 00:08:18.869
you would start to just see the you know


00:08:18.879 --> 00:08:21.670
the as you said the that fit that sort


00:08:21.680 --> 00:08:23.830
of pale gray appearance where you're


00:08:23.840 --> 00:08:25.589
looking at very low light low light


00:08:25.599 --> 00:08:27.270
levels indeed where the color cells


00:08:27.280 --> 00:08:29.270
aren't receptive.


00:08:29.280 --> 00:08:31.029
>> There you go Lee. Uh the answer to your


00:08:31.039 --> 00:08:33.029
question is yes to all of the above


00:08:33.039 --> 00:08:35.190
basically. [clears throat]


00:08:35.200 --> 00:08:37.750
>> Great question. Excellent question. All


00:08:37.760 --> 00:08:39.589
right, let's move on. This is from


00:08:39.599 --> 00:08:40.870
Fenton.


00:08:40.880 --> 00:08:43.430
>> Yeah. Hello, Fred and Andrew. This is


00:08:43.440 --> 00:08:46.550
Fenton contacting you from St. Paul,


00:08:46.560 --> 00:08:51.190
Minnesota in the US. Um, I sort of have


00:08:51.200 --> 00:08:53.750
a different type of astrophysical


00:08:53.760 --> 00:08:58.150
question for you and this is on how to


00:08:58.160 --> 00:09:02.150
shield astronauts from radiation outside


00:09:02.160 --> 00:09:05.670
of the Van Allen belt. Um, I was curious


00:09:05.680 --> 00:09:08.949
if you know of any pending technologies


00:09:08.959 --> 00:09:11.750
that would allow this. Obvious choice


00:09:11.760 --> 00:09:14.070
would some people would say is lead, but


00:09:14.080 --> 00:09:16.230
I can think of several reasons why this


00:09:16.240 --> 00:09:19.590
is not a good idea. How about a


00:09:19.600 --> 00:09:22.949
miniature Van Allen belt which could


00:09:22.959 --> 00:09:26.310
surround a spacecraft? How does that


00:09:26.320 --> 00:09:29.350
sound? How could this become


00:09:29.360 --> 00:09:31.990
reality? Thank you very much. I hope you


00:09:32.000 --> 00:09:34.870
like the question. Bye now.


00:09:34.880 --> 00:09:36.790
>> Thanks, Fenton. Fenton always has these


00:09:36.800 --> 00:09:38.949
intriguing thoughts. I I've noticed in


00:09:38.959 --> 00:09:41.110
the times that we've heard from him. Um


00:09:41.120 --> 00:09:42.870
maybe we should start by explaining what


00:09:42.880 --> 00:09:44.870
the Van Allen belt is for those of us


00:09:44.880 --> 00:09:48.710
who just can't remember like me.


00:09:48.720 --> 00:09:54.870
Um it's uh so the van element bel


00:09:54.880 --> 00:09:57.030
you know the magnetic shielding around


00:09:57.040 --> 00:10:01.590
the earth uh which is uh


00:10:01.600 --> 00:10:03.829
caused by the the magnetism of the


00:10:03.839 --> 00:10:05.910
earth. It's caused by the uh the fact


00:10:05.920 --> 00:10:10.070
that we've got an iron core and uh


00:10:10.080 --> 00:10:11.910
basically it's in two parts. It's solid


00:10:11.920 --> 00:10:13.750
and liquid. So it acts like a dynamo.


00:10:13.760 --> 00:10:16.630
it's rotating and that gives us this uh


00:10:16.640 --> 00:10:20.069
exactly the protection that um that um


00:10:20.079 --> 00:10:23.110
um Fenton is talking about. Um yeah,


00:10:23.120 --> 00:10:26.790
>> I was going to refer I'm a bit annoyed


00:10:26.800 --> 00:10:29.030
actually because I've lost it. Uh there


00:10:29.040 --> 00:10:34.069
is a very nice article on uh it's


00:10:34.079 --> 00:10:38.790
actually on the um BBC's website uh


00:10:38.800 --> 00:10:41.269
their Sky at Night website. There's a


00:10:41.279 --> 00:10:43.670
lovely article on exactly this. Here it


00:10:43.680 --> 00:10:45.990
is. I found it. I hadn't lost it. How


00:10:46.000 --> 00:10:47.990
astronauts can hide from radiation on


00:10:48.000 --> 00:10:52.949
Mars and it goes into uh the exactly the


00:10:52.959 --> 00:10:54.710
problem that uh that Fenton's talking


00:10:54.720 --> 00:10:56.550
about. How do you present how do you


00:10:56.560 --> 00:11:00.710
prevent u astronauts basically becoming


00:11:00.720 --> 00:11:02.310
irradiated


00:11:02.320 --> 00:11:06.949
uh and over time it's basically lethal


00:11:06.959 --> 00:11:08.949
uh because because of the cosmic


00:11:08.959 --> 00:11:11.269
radiation that's coming down through


00:11:11.279 --> 00:11:16.550
space uh and it it does cell damage uh


00:11:16.560 --> 00:11:19.030
in your body uh and it can actually


00:11:19.040 --> 00:11:22.389
trigger cancer. So um the the whole


00:11:22.399 --> 00:11:27.269
study of this is uh or sorry the the


00:11:27.279 --> 00:11:29.590
thrust of this article BBC Sky at Night


00:11:29.600 --> 00:11:33.430
magazine uh is to discuss how you might


00:11:33.440 --> 00:11:35.829
protect astronauts uh from the


00:11:35.839 --> 00:11:38.230
radiation. Uh and that's not just on


00:11:38.240 --> 00:11:42.069
Mars but on route. Uh okay.


00:11:42.079 --> 00:11:46.069
Uh the solution that that Fenton has


00:11:46.079 --> 00:11:48.550
suggested is covered in a paragraph. I'm


00:11:48.560 --> 00:11:49.910
going to read it because we've quoted


00:11:49.920 --> 00:11:53.990
where the source is. Uh, for example,


00:11:54.000 --> 00:11:55.750
all right, let me no, let me go back a


00:11:55.760 --> 00:11:57.509
paragraph. One, one method of helping


00:11:57.519 --> 00:11:59.509
astronauts to avoid the radiation on


00:11:59.519 --> 00:12:03.190
Mars is active shielding. For example,


00:12:03.200 --> 00:12:05.590
superconducting electromagnets could be


00:12:05.600 --> 00:12:08.150
used to create a powerful magnetic field


00:12:08.160 --> 00:12:09.829
to deflect the incoming charged


00:12:09.839 --> 00:12:11.910
radiation particles away just as the


00:12:11.920 --> 00:12:13.990
Earth's field does. That's the lanel


00:12:14.000 --> 00:12:16.710
belt. The problem is that such solutions


00:12:16.720 --> 00:12:19.430
can demand a lot of power to run and the


00:12:19.440 --> 00:12:21.430
technology is a long way from being


00:12:21.440 --> 00:12:24.310
fully developed. An easier alternative


00:12:24.320 --> 00:12:26.470
is passive shielding. Simply placing a


00:12:26.480 --> 00:12:28.949
thick bulk of shielding material between


00:12:28.959 --> 00:12:32.389
the crew habitat and the sky. Uh and


00:12:32.399 --> 00:12:34.629
then they go on to consider different


00:12:34.639 --> 00:12:38.790
materials. Aluminium aka aluminum. Uh


00:12:38.800 --> 00:12:40.389
the metal that spacecraft are


00:12:40.399 --> 00:12:42.069
constructed from is actually a pretty


00:12:42.079 --> 00:12:45.750
bad radiation shield. Um, and they say


00:12:45.760 --> 00:12:48.550
when hit by an energetic cosmic ray, its


00:12:48.560 --> 00:12:50.470
atoms can shatter and fly onwards to


00:12:50.480 --> 00:12:53.269
create even more radiation particles.


00:12:53.279 --> 00:12:55.509
And Martian soil, the regalith, uh,


00:12:55.519 --> 00:12:57.190
which if you're on Mars, you might think


00:12:57.200 --> 00:12:59.990
about digging a hole there. Uh, it's got


00:13:00.000 --> 00:13:02.710
the same problem, but it's it's actually


00:13:02.720 --> 00:13:06.230
uh, you know, abundant. Um, and so you


00:13:06.240 --> 00:13:09.269
could use that to dig a pole. If you put


00:13:09.279 --> 00:13:12.069
a two to three meter layer on top of


00:13:12.079 --> 00:13:15.430
your habitat, uh then you'll you'll get


00:13:15.440 --> 00:13:17.990
some protection. But uh the thing that


00:13:18.000 --> 00:13:20.790
surprised me, Andrew, uh is once again


00:13:20.800 --> 00:13:23.430
it comes from this same article. Uh


00:13:23.440 --> 00:13:26.230
hydrogen is the best shielding material


00:13:26.240 --> 00:13:28.949
as it's light atoms. Yeah. It's light


00:13:28.959 --> 00:13:32.069
atoms. Uh and by light, I mean not


00:13:32.079 --> 00:13:34.389
heavy. Its light atoms don't create as


00:13:34.399 --> 00:13:37.110
much secondary radiation. And so tanks


00:13:37.120 --> 00:13:40.310
of rocket fuel or water, which is rich


00:13:40.320 --> 00:13:42.629
in hydrogen, placed over crew quarters


00:13:42.639 --> 00:13:44.470
could double up as effective radiation


00:13:44.480 --> 00:13:47.350
shields. I've heard that before that um


00:13:47.360 --> 00:13:49.190
you know, one way of protecting your


00:13:49.200 --> 00:13:51.190
spacecraft as it flies to Mars is put it


00:13:51.200 --> 00:13:53.590
put it in a tank of water. Uh it's the


00:13:53.600 --> 00:13:56.069
last thing you'd expect to do, but uh


00:13:56.079 --> 00:13:58.470
water is a good shielding material. And


00:13:58.480 --> 00:14:01.829
they also uh point out the alternative


00:14:01.839 --> 00:14:03.590
of hydrogen-rich plastics like


00:14:03.600 --> 00:14:06.310
polyethylene could be used to cement


00:14:06.320 --> 00:14:08.069
regalith grains together. This is on


00:14:08.079 --> 00:14:10.949
Mars and improve their shielding effect.


00:14:10.959 --> 00:14:13.590
Um so uh if you want to read more about


00:14:13.600 --> 00:14:15.430
this, it's an article that originally


00:14:15.440 --> 00:14:18.710
appeared in the August 22 2022 issue of


00:14:18.720 --> 00:14:21.269
BBC Skylight magazine and it covers


00:14:21.279 --> 00:14:23.350
pretty well most of the ideas uh that


00:14:23.360 --> 00:14:25.590
have been that have been suggested for


00:14:25.600 --> 00:14:27.670
this radiation issue. It's one that's


00:14:27.680 --> 00:14:29.269
got to, you know, it's got to find an


00:14:29.279 --> 00:14:32.790
answer soon because uh good old Elon and


00:14:32.800 --> 00:14:35.670
his Starship uh is getting nearer to


00:14:35.680 --> 00:14:36.949
thinking about going to Mars. I don't


00:14:36.959 --> 00:14:38.550
think it's ever going to happen, but um


00:14:38.560 --> 00:14:40.710
that's uh uh that's something he'll


00:14:40.720 --> 00:14:42.710
definitely be thinking about.


00:14:42.720 --> 00:14:44.629
>> Yes, indeed. Well, he's he's too busy


00:14:44.639 --> 00:14:45.829
dealing with the Australian government


00:14:45.839 --> 00:14:46.629
at the moment.


00:14:46.639 --> 00:14:48.790
>> Yes, indeed. That's that's right.


00:14:48.800 --> 00:14:50.470
>> Some of the content on Twitter that the


00:14:50.480 --> 00:14:53.030
government wants to get rid of simply


00:14:53.040 --> 00:14:55.030
because of its um volatility. But


00:14:55.040 --> 00:14:56.870
anyway, that's a different story. Uh but


00:14:56.880 --> 00:14:59.110
there plenty of water on Mars. So maybe


00:14:59.120 --> 00:15:01.509
maybe creating those water barriers is


00:15:01.519 --> 00:15:03.590
is probably the simplest thing to do.


00:15:03.600 --> 00:15:05.430
You've already got the material there


00:15:05.440 --> 00:15:07.110
>> if you've if you've landed in the right


00:15:07.120 --> 00:15:09.509
spot where you've got or whatever.


00:15:09.519 --> 00:15:11.750
>> That's the question. Yes, indeed. Well


00:15:11.760 --> 00:15:13.509
done, Fent Fenton. You you actually


00:15:13.519 --> 00:15:15.110
happened across some of the uh the


00:15:15.120 --> 00:15:18.150
answers too in uh asking your question.


00:15:18.160 --> 00:15:20.629
>> Uh this is Space Nuts. Andrew Dunley


00:15:20.639 --> 00:15:25.670
here with Professor Fred Watson.


00:15:25.680 --> 00:15:28.470
3 2 1


00:15:28.480 --> 00:15:31.269
>> space nuts. Now Fred, uh, our next


00:15:31.279 --> 00:15:33.509
question comes from Robert. Hi guys,


00:15:33.519 --> 00:15:35.269
love your show. Sorry for the long


00:15:35.279 --> 00:15:37.829
question, but feel free to paraphrase uh


00:15:37.839 --> 00:15:40.710
or shorten it. Our moon is heavily


00:15:40.720 --> 00:15:42.870
created and has given us a lot of


00:15:42.880 --> 00:15:44.470
insight into the history of the solar


00:15:44.480 --> 00:15:46.230
system and perhaps how the planets


00:15:46.240 --> 00:15:49.350
formed. But what if we had a moon like


00:15:49.360 --> 00:15:52.629
the icy moon Europa or the shrouded in


00:15:52.639 --> 00:15:55.749
haze Titan, both of which don't show


00:15:55.759 --> 00:15:58.069
immediate evidence of cratering? Would


00:15:58.079 --> 00:16:00.629
our theory about how the planets


00:16:00.639 --> 00:16:03.430
developed would be different? What other


00:16:03.440 --> 00:16:05.829
insights about our solar system would be


00:16:05.839 --> 00:16:08.389
missing or or would we be missing? And


00:16:08.399 --> 00:16:11.110
lastly, uh would we have spent uh or


00:16:11.120 --> 00:16:13.189
would we have sent people to land on


00:16:13.199 --> 00:16:17.749
such moons? I.e. Uh, would they be more


00:16:17.759 --> 00:16:19.990
dangerous for astronauts? Uh, cheers,


00:16:20.000 --> 00:16:22.470
Robert in Vienna, Austria. Wow. I don't


00:16:22.480 --> 00:16:23.829
think we've had a question from Vienna


00:16:23.839 --> 00:16:25.269
before, have we?


00:16:25.279 --> 00:16:27.189
>> Lovely to hear from you, Robert.


00:16:27.199 --> 00:16:28.710
>> I think I think Robert might have been


00:16:28.720 --> 00:16:30.069
in touch once before. I can't


00:16:30.079 --> 00:16:32.470
>> Oh, I might have been too.


00:16:32.480 --> 00:16:34.710
And here from Vienna. Yeah, I was in


00:16:34.720 --> 00:16:36.150
Vienna at the beginning of last year and


00:16:36.160 --> 00:16:37.910
I think I think we got something around


00:16:37.920 --> 00:16:40.069
about the same time and I was waxing


00:16:40.079 --> 00:16:42.389
lyrical about being in Vienna at the UN


00:16:42.399 --> 00:16:45.269
when I was at the Copas meeting. Anyway,


00:16:45.279 --> 00:16:47.990
uh that's another another issue. Uh what


00:16:48.000 --> 00:16:49.670
if we had a Yeah, it's a really


00:16:49.680 --> 00:16:53.670
interesting question. Um, what would we


00:16:53.680 --> 00:16:57.350
not know about the solar system if our


00:16:57.360 --> 00:17:01.749
moon was basically uh one that had been


00:17:01.759 --> 00:17:05.829
resurfaced in recent years or millennia


00:17:05.839 --> 00:17:07.429
because that's what makes a surface


00:17:07.439 --> 00:17:10.949
smooth. That's how we recognize


00:17:10.959 --> 00:17:13.909
um the fact that the universe sorry that


00:17:13.919 --> 00:17:15.429
the


00:17:15.439 --> 00:17:17.350
it's how we recognize the age of a


00:17:17.360 --> 00:17:19.669
surface is by how many craters it's got.


00:17:19.679 --> 00:17:21.829
The old the older the surface, the more


00:17:21.839 --> 00:17:24.710
craters it has. And so the moon's south


00:17:24.720 --> 00:17:26.309
southern region, which is heavily


00:17:26.319 --> 00:17:29.190
cratered, as is the backside, uh tell us


00:17:29.200 --> 00:17:31.510
that uh early on in the solar systems


00:17:31.520 --> 00:17:34.150
history, it was a very wild and woolly


00:17:34.160 --> 00:17:36.070
place with things charging about all


00:17:36.080 --> 00:17:38.789
over and causing these craters. Now, if


00:17:38.799 --> 00:17:40.950
we had a moon that was like Europa that


00:17:40.960 --> 00:17:45.270
um had, you know, icy geysers on it that


00:17:45.280 --> 00:17:47.430
basically covered up the craters, would


00:17:47.440 --> 00:17:50.470
we have known about that? My guess is


00:17:50.480 --> 00:17:52.789
yes, we would because we'd see other


00:17:52.799 --> 00:17:55.669
bodies within the solar system uh like


00:17:55.679 --> 00:17:59.430
you know other moons like um places like


00:17:59.440 --> 00:18:02.630
um um series the the biggest of the


00:18:02.640 --> 00:18:03.990
asteroids the dwarf planet that


00:18:04.000 --> 00:18:05.909
dominates the asteroid belt that's


00:18:05.919 --> 00:18:08.789
heavily created. Uh parts of Pluto are


00:18:08.799 --> 00:18:12.310
heavily crated. Um


00:18:12.320 --> 00:18:15.669
Mimas uh one of Saturn's moon is moons


00:18:15.679 --> 00:18:18.150
is heavily created too. So, so we we'd


00:18:18.160 --> 00:18:19.830
know about it by looking at other


00:18:19.840 --> 00:18:23.029
objects even if our own moon was uh


00:18:23.039 --> 00:18:26.710
smoothly surfaced. Um it's it's a but


00:18:26.720 --> 00:18:30.950
the Robert's last point uh on this uh


00:18:30.960 --> 00:18:33.190
would we have sent people to land on


00:18:33.200 --> 00:18:37.110
such a moon? Uh I think um I don't know


00:18:37.120 --> 00:18:38.950
that's a really good question. I mean we


00:18:38.960 --> 00:18:40.950
have sent people to land on our moon as


00:18:40.960 --> 00:18:44.230
it stands uh with an ancient surface. In


00:18:44.240 --> 00:18:47.110
fact, where they landed were more recent


00:18:47.120 --> 00:18:49.029
uh than the heavily cratered surfaces


00:18:49.039 --> 00:18:50.150
because they were principally in the


00:18:50.160 --> 00:18:52.710
Maria, the the basalt planes.


00:18:52.720 --> 00:18:53.669
>> Yeah.


00:18:53.679 --> 00:18:57.029
>> So maybe that suggests that we would


00:18:57.039 --> 00:18:59.750
have landed people on Europa as well. Uh


00:18:59.760 --> 00:19:00.150
because


00:19:00.160 --> 00:19:02.549
>> I think we pro Yeah, we probably would


00:19:02.559 --> 00:19:05.029
because it would have a solid surface.


00:19:05.039 --> 00:19:07.350
There'd be places because it would be so


00:19:07.360 --> 00:19:09.110
close to us, we'd be able to examine and


00:19:09.120 --> 00:19:12.230
and find the the right landing points.


00:19:12.240 --> 00:19:14.710
might be a bit more difficult with a


00:19:14.720 --> 00:19:18.070
moon that's shrouded in land gas.


00:19:18.080 --> 00:19:19.270
>> Yeah. Yeah.


00:19:19.280 --> 00:19:21.750
>> Yeah, that's right. Uh and especially um


00:19:21.760 --> 00:19:25.110
place like Titan. Uh


00:19:25.120 --> 00:19:27.110
I I still think we'd have done it.


00:19:27.120 --> 00:19:30.950
Actually, I think um you know the JFK's


00:19:30.960 --> 00:19:33.190
uh promise to put astronauts on the moon


00:19:33.200 --> 00:19:35.110
would have still held good even if it


00:19:35.120 --> 00:19:36.789
had been a very different place. If it


00:19:36.799 --> 00:19:39.510
had been like Io, uh, it might have been


00:19:39.520 --> 00:19:41.270
a different story where, you know,


00:19:41.280 --> 00:19:43.270
you've got the most volcanically active


00:19:43.280 --> 00:19:45.270
body in the entire solar system with


00:19:45.280 --> 00:19:47.190
stuff going off all over the place. I


00:19:47.200 --> 00:19:48.230
think we might have been a bit more


00:19:48.240 --> 00:19:51.830
reluctant to to land on a Yes, possibly.


00:19:51.840 --> 00:19:54.230
So, uh, it would be interesting to have


00:19:54.240 --> 00:19:55.590
something different, but then if we'd


00:19:55.600 --> 00:19:57.990
always had if if we'd always had an ice


00:19:58.000 --> 00:20:00.390
moon, we probably would have caught a


00:20:00.400 --> 00:20:03.190
question from Robert asking, "What if we


00:20:03.200 --> 00:20:07.590
had a rocky moon?" Now, would we Would


00:20:07.600 --> 00:20:09.510
we have a different interpretation of


00:20:09.520 --> 00:20:11.110
four masses of planets if there was a


00:20:11.120 --> 00:20:12.870
rocky moon next to us instead of an ice


00:20:12.880 --> 00:20:15.430
moon? Yes. Um, in an alternative


00:20:15.440 --> 00:20:16.950
universe, Robert, you would have flipped


00:20:16.960 --> 00:20:18.789
your question. Good to hear from you.


00:20:18.799 --> 00:20:21.430
Hope all all is well in Austria. Our


00:20:21.440 --> 00:20:23.430
final question for this episode comes


00:20:23.440 --> 00:20:25.350
from Duncan.


00:20:25.360 --> 00:20:29.270
>> Hello. Duncan here from Wayouth in the


00:20:29.280 --> 00:20:34.390
UK. Again, a quick question.


00:20:34.400 --> 00:20:36.710
just looking was just doing some reading


00:20:36.720 --> 00:20:39.909
and I noticed that Uranus and Neptune


00:20:39.919 --> 00:20:44.070
are often referred to as ice giants.


00:20:44.080 --> 00:20:48.870
Now, given that ice is basically just


00:20:48.880 --> 00:20:53.510
sort of like a rock form of water or CO2


00:20:53.520 --> 00:20:56.630
or whatever else, but basically just a


00:20:56.640 --> 00:20:59.110
solid form of it. Why are they not just


00:20:59.120 --> 00:21:03.270
called rock giants? Why do we make the


00:21:03.280 --> 00:21:05.750
definition of ice rather than just


00:21:05.760 --> 00:21:08.630
calling them rock? It just seems odd


00:21:08.640 --> 00:21:11.669
because the little planets in the inner


00:21:11.679 --> 00:21:13.830
solar system are referred to as rocky


00:21:13.840 --> 00:21:17.430
planets. So given that they're also


00:21:17.440 --> 00:21:19.110
apparently rocky, why are they not


00:21:19.120 --> 00:21:21.669
called rocky giants?


00:21:21.679 --> 00:21:26.149
Okay, thank you. Bye. Thanks Duncan.


00:21:26.159 --> 00:21:28.630
Appreciate your questions as always. Uh


00:21:28.640 --> 00:21:30.789
yeah. Why do we call them ice giants


00:21:30.799 --> 00:21:32.870
just for the sake of the exercise? Cuz


00:21:32.880 --> 00:21:36.390
there's gas giants and ice giants.


00:21:36.400 --> 00:21:38.950
>> Yeah, except one is a subset of the


00:21:38.960 --> 00:21:42.149
other. And so all four of the outer


00:21:42.159 --> 00:21:44.390
planets, Jupiter, Saturn, Neptune,


00:21:44.400 --> 00:21:46.549
sorry, Uranus, and Neptune, they're all


00:21:46.559 --> 00:21:51.430
gas giants because they have uh eye mass


00:21:51.440 --> 00:21:55.590
uh um you know, much more in the case of


00:21:55.600 --> 00:21:57.909
Jupiter certainly than uh than our own


00:21:57.919 --> 00:22:01.110
planet. Um the they've got they're


00:22:01.120 --> 00:22:03.029
giants. They're big. They've got high


00:22:03.039 --> 00:22:07.350
mass. Uh and they don't have a visible


00:22:07.360 --> 00:22:09.510
surface, which is why they're called gas


00:22:09.520 --> 00:22:11.590
giants because all we see is a gasy


00:22:11.600 --> 00:22:15.510
envelope. Um just to go to the last of


00:22:15.520 --> 00:22:17.270
Duncan's questions there, we we wouldn't


00:22:17.280 --> 00:22:19.990
call the inner planets rocky giants


00:22:20.000 --> 00:22:21.909
because they're not giants. They're kind


00:22:21.919 --> 00:22:23.510
of normal planet size. You know, if you


00:22:23.520 --> 00:22:25.110
if you think of the Earth as being your


00:22:25.120 --> 00:22:28.789
standard planet, then uh Mercury, Venus,


00:22:28.799 --> 00:22:32.070
and Mars are similar in size. They're


00:22:32.080 --> 00:22:33.990
all smaller. Venus is about the same


00:22:34.000 --> 00:22:35.590
size, but Mercury and Mars, of course,


00:22:35.600 --> 00:22:38.390
are smaller. So, uh so it's only when


00:22:38.400 --> 00:22:40.710
you compare with the size of Earth that


00:22:40.720 --> 00:22:42.470
you'd start talking about giants because


00:22:42.480 --> 00:22:44.470
they are much much bigger than Earth.


00:22:44.480 --> 00:22:47.430
And so, that's the gas giants. So, why


00:22:47.440 --> 00:22:50.149
are Uranus and Neptune called ice


00:22:50.159 --> 00:22:55.350
giants? because they have hazes of ice


00:22:55.360 --> 00:22:57.270
in their atmosphere.


00:22:57.280 --> 00:23:00.149
>> So, uh, and that's the the trick. It's


00:23:00.159 --> 00:23:02.710
not a solid surface. It's not rock.


00:23:02.720 --> 00:23:04.789
[snorts] It's it's a haze. It's kind of


00:23:04.799 --> 00:23:07.990
like a a dust of ice which permeates


00:23:08.000 --> 00:23:10.230
their atmosphere. And and and it's water


00:23:10.240 --> 00:23:14.310
ice in fact, uh, mostly. Uh so that's


00:23:14.320 --> 00:23:15.990
why they're called ice giants because


00:23:16.000 --> 00:23:19.029
unlike Saturn and Jupiter uh which don't


00:23:19.039 --> 00:23:21.669
have these hazes uh the the outer the


00:23:21.679 --> 00:23:25.110
rocky rock sorry the two outer planets


00:23:25.120 --> 00:23:27.750
Uranus and Neptune do they have ice


00:23:27.760 --> 00:23:29.350
hazes in their atmosphere hence the


00:23:29.360 --> 00:23:30.950
name.


00:23:30.960 --> 00:23:33.430
Okay. Yeah. And because last episode we


00:23:33.440 --> 00:23:35.750
learned there wasn't much water in


00:23:35.760 --> 00:23:37.830
Jupiter's


00:23:37.840 --> 00:23:41.430
>> in the in the two outer gas giants.


00:23:41.440 --> 00:23:42.789
Yeah. It sounds like there is. Is that


00:23:42.799 --> 00:23:46.390
why they're a different color? Yes. Yes,


00:23:46.400 --> 00:23:48.310
I think that's right. They're um and and


00:23:48.320 --> 00:23:49.830
also their their atmospheric


00:23:49.840 --> 00:23:51.990
constituents are are different. They


00:23:52.000 --> 00:23:53.750
don't have the same belt structure that


00:23:53.760 --> 00:23:56.549
Saturn and Jupiter do. Uh it may be that


00:23:56.559 --> 00:23:58.789
that's because any belts that exist are


00:23:58.799 --> 00:24:00.549
much lower in the atmosphere and so you


00:24:00.559 --> 00:24:03.669
don't see them. Um yeah, I mean uh


00:24:03.679 --> 00:24:08.070
there's there's a strong body of uh of


00:24:08.080 --> 00:24:11.909
advocacy within the space fraternity to


00:24:11.919 --> 00:24:16.710
get get more spacecraft out to Uranus


00:24:16.720 --> 00:24:19.510
and Neptune cuz they're the two planets


00:24:19.520 --> 00:24:22.549
about which we know least. Um and uh


00:24:22.559 --> 00:24:24.710
will be good to know more.


00:24:24.720 --> 00:24:27.510
>> Yeah. Well, if you sit down in snow for


00:24:27.520 --> 00:24:29.430
long enough, your Uranus turns into a


00:24:29.440 --> 00:24:32.149
nice giant sun.


00:24:32.159 --> 00:24:36.710
I couldn't help it. Sorry. Uh, yeah.


00:24:36.720 --> 00:24:38.549
>> Which is why we call it Uranus in


00:24:38.559 --> 00:24:39.590
politics.


00:24:39.600 --> 00:24:41.190
>> I know. I know.


00:24:41.200 --> 00:24:43.669
>> Yeah. But it's just a joke you've got to


00:24:43.679 --> 00:24:46.630
tell. It's just you have to.


00:24:46.640 --> 00:24:49.669
>> Yes. I blame Johannes Borda, who is the


00:24:49.679 --> 00:24:52.149
person who chose the name. It's fine in


00:24:52.159 --> 00:24:54.470
German. Uess. Uess. There's nothing


00:24:54.480 --> 00:24:57.430
wrong with that. It's great. Yeah. Ruins


00:24:57.440 --> 00:24:59.830
all the jokes, bro.


00:24:59.840 --> 00:25:01.830
>> All right. So, yes, they're ice giants


00:25:01.840 --> 00:25:03.269
for a very good reason, Duncan, because


00:25:03.279 --> 00:25:05.350
they've got ice in them uh in the


00:25:05.360 --> 00:25:07.110
atmosphere. But technically speaking,


00:25:07.120 --> 00:25:09.430
they are in fact gas giants. But


00:25:09.440 --> 00:25:11.590
>> yes, we differentiate them because of


00:25:11.600 --> 00:25:13.350
their substantially different


00:25:13.360 --> 00:25:15.430
atmospheres. There you are. Thanks,


00:25:15.440 --> 00:25:17.269
Duncan. Great to hear from you. Great to


00:25:17.279 --> 00:25:18.710
hear from everybody. Thanks for sending


00:25:18.720 --> 00:25:20.230
in your questions. Don't forget you can


00:25:20.240 --> 00:25:21.830
send in questions via our website


00:25:21.840 --> 00:25:23.990
spacenutpodcast.com


00:25:24.000 --> 00:25:25.510
spacenuts.io


00:25:25.520 --> 00:25:27.029
and all you have to do is click on the


00:25:27.039 --> 00:25:28.950
various links on the right hand side.


00:25:28.960 --> 00:25:30.549
Send us your question. That's audio


00:25:30.559 --> 00:25:32.870
questions only. Uh or you can send us


00:25:32.880 --> 00:25:35.750
text and audio questions via the AMA tab


00:25:35.760 --> 00:25:37.590
up the top. It's your choice. Don't


00:25:37.600 --> 00:25:38.870
forget to tell us who you are and where


00:25:38.880 --> 00:25:39.990
you're from and have a look around while


00:25:40.000 --> 00:25:42.950
you're on our website or join our media


00:25:42.960 --> 00:25:44.950
uh social media platforms, Facebook,


00:25:44.960 --> 00:25:46.870
Instagram, YouTube, where you can


00:25:46.880 --> 00:25:49.510
subscribe just by pressing the subscribe


00:25:49.520 --> 00:25:52.630
button below which yes, it's down there


00:25:52.640 --> 00:25:55.029
somewhere. I don't know, one of those


00:25:55.039 --> 00:25:57.510
places. Uh Fred, as always, thank you so


00:25:57.520 --> 00:26:00.470
much. Pleasure, Andrew. See you soon.


00:26:00.480 --> 00:26:02.950
>> Okay, Fred Watson, astronomer at large.


00:26:02.960 --> 00:26:04.310
We'll catch him on the next episode of


00:26:04.320 --> 00:26:06.390
Space Nuts. might catch Hugh then as


00:26:06.400 --> 00:26:09.190
well because um


00:26:09.200 --> 00:26:11.430
not here today. Didn't even call in


00:26:11.440 --> 00:26:13.909
sick. I need a note. And from me, Andrew


00:26:13.919 --> 00:26:15.350
Dumprey, thanks very much for your


00:26:15.360 --> 00:26:17.190
company. We'll see you again soon on the


00:26:17.200 --> 00:26:19.750
next episode of Space Nuts. Bye-bye.


00:26:19.760 --> 00:26:20.710
>> Space Nuts.


00:26:20.720 --> 00:26:22.870
>> You'll be listening to the Space Nuts


00:26:22.880 --> 00:26:25.110
podcast


00:26:25.120 --> 00:26:28.070
>> available at Apple Podcasts, Spotify,


00:26:28.080 --> 00:26:30.149
iHeart Radio, [music] or your favorite


00:26:30.159 --> 00:26:32.470
podcast player. You can also stream on


00:26:32.480 --> 00:26:35.110
demand at byes.com. This has been


00:26:35.120 --> 00:26:36.898
another quality podcast production


00:26:36.908 --> 00:26:40.600
[music] from sites.com.