1 00:00:08,440 --> 00:00:11,600 Speaker 1: A Kelly, how was your family trip? Oh? It was 2 00:00:11,680 --> 00:00:13,920 Speaker 1: so much fun. Did you guys get to break out 3 00:00:13,920 --> 00:00:17,439 Speaker 1: of your usual routines experience something different? Yeah, And something 4 00:00:17,480 --> 00:00:20,400 Speaker 1: that was unusual for our kids was eating at restaurants. 5 00:00:20,800 --> 00:00:22,800 Speaker 1: We don't do a lot of that when we're at home, 6 00:00:22,880 --> 00:00:24,040 Speaker 1: and you know, we didn't do a lot of it 7 00:00:24,040 --> 00:00:26,840 Speaker 1: because of COVID and stuff. So that was new. And though, 8 00:00:26,880 --> 00:00:29,120 Speaker 1: what is it that your kids like about eating out 9 00:00:29,160 --> 00:00:32,200 Speaker 1: at restaurants? Aren't you guys like super good cooks at home? Well, 10 00:00:32,479 --> 00:00:34,680 Speaker 1: we keep me out of the kitchen for everyone's sake, 11 00:00:34,760 --> 00:00:37,120 Speaker 1: but that is a really good cook, so that's good. 12 00:00:37,560 --> 00:00:39,720 Speaker 1: But I think for the kids, they mostly like the 13 00:00:39,760 --> 00:00:43,400 Speaker 1: novelty of it, you know, the atmosphere. M Well, that's exciting, 14 00:00:43,400 --> 00:00:45,680 Speaker 1: but it doesn't actually bode very well for them as 15 00:00:45,840 --> 00:00:49,680 Speaker 1: future space colonists. No, I'm not following. What do you mean, Well, 16 00:00:49,720 --> 00:01:10,840 Speaker 1: I hear that restaurants on the moon have no atmosphere. Oh. Hi, 17 00:01:11,040 --> 00:01:14,399 Speaker 1: I'm Daniel. I'm a particle physicist and a professor at 18 00:01:14,480 --> 00:01:17,240 Speaker 1: U C Irvine, and I'm always in the mood for 19 00:01:17,280 --> 00:01:20,840 Speaker 1: a good space pun. I'm Kelly Weener Smith. I'm an 20 00:01:20,840 --> 00:01:24,040 Speaker 1: adjunct assistant professor at Grace University, and I am also 21 00:01:24,080 --> 00:01:26,800 Speaker 1: a fan of the puns, especially the moon based ones. 22 00:01:27,000 --> 00:01:29,399 Speaker 1: There's a lot of inappropriate moon based puns that we 23 00:01:29,400 --> 00:01:31,080 Speaker 1: can make right now. Yeah, sure, no, you and I 24 00:01:31,160 --> 00:01:32,760 Speaker 1: are pretty good at that. But what we're going to 25 00:01:32,880 --> 00:01:35,440 Speaker 1: keep it clean. We are definitely gonna keep it clean 26 00:01:35,560 --> 00:01:39,440 Speaker 1: as we examine the deep dark mysteries of the universe. 27 00:01:39,800 --> 00:01:43,520 Speaker 1: And welcome to the podcast. Daniel and Jorge explain the 28 00:01:43,640 --> 00:01:47,560 Speaker 1: universe in which we do exactly that, ask the biggest, darkest, 29 00:01:47,560 --> 00:01:50,760 Speaker 1: deepest questions about everything that's out there in the universe. 30 00:01:50,880 --> 00:01:53,000 Speaker 1: We don't want to sweep anything under the rug. We 31 00:01:53,040 --> 00:01:55,960 Speaker 1: want to expose it all to the blinding glare of 32 00:01:56,120 --> 00:01:59,280 Speaker 1: sunlight and make it all makes sense to you. My 33 00:01:59,480 --> 00:02:02,520 Speaker 1: usual host, Orgy can't be here today, so we are 34 00:02:02,640 --> 00:02:05,560 Speaker 1: delighted to have one of our regular co hosts, Kelly. Kelly. 35 00:02:05,560 --> 00:02:08,240 Speaker 1: Thank you very much for joining us today. I'm delighted 36 00:02:08,280 --> 00:02:10,400 Speaker 1: to be back, Okelly. When you're on the podcast, we're 37 00:02:10,440 --> 00:02:13,520 Speaker 1: often talking about space and about the wonders of the 38 00:02:13,639 --> 00:02:17,240 Speaker 1: night sky, putting people out there mentally sort of at night, 39 00:02:17,400 --> 00:02:20,560 Speaker 1: staring up in the stars, being amazed at everything that 40 00:02:20,600 --> 00:02:23,080 Speaker 1: we are seeing that's right, and then you turn it 41 00:02:23,120 --> 00:02:25,760 Speaker 1: into something about how we're all going to die. But yes, 42 00:02:25,960 --> 00:02:28,680 Speaker 1: we are usually looking up at the night sky and 43 00:02:28,720 --> 00:02:31,160 Speaker 1: having a sense of all about it all because one 44 00:02:31,200 --> 00:02:32,960 Speaker 1: of the things that I love about science is that 45 00:02:33,000 --> 00:02:35,760 Speaker 1: it lifts us up away from our everyday lives. It 46 00:02:35,800 --> 00:02:40,080 Speaker 1: forces us to turn our eyes skywords and think about 47 00:02:40,080 --> 00:02:43,360 Speaker 1: what's out there in the universe. Usually that's something we 48 00:02:43,520 --> 00:02:46,160 Speaker 1: do at night because during the day the sun is 49 00:02:46,200 --> 00:02:49,639 Speaker 1: so bright it keeps us from seeing everything that's out there. 50 00:02:49,639 --> 00:02:52,320 Speaker 1: That makes us wonder, that makes us as deep questions 51 00:02:52,360 --> 00:02:55,040 Speaker 1: about the very nature of the universe. But you know, 52 00:02:55,200 --> 00:02:58,440 Speaker 1: everything that's out there is also out there during the daytime, 53 00:02:58,680 --> 00:03:00,320 Speaker 1: and I remember that blew my mind when I was 54 00:03:00,360 --> 00:03:02,200 Speaker 1: a kid and I first learned that. But yeah, it's 55 00:03:02,240 --> 00:03:04,120 Speaker 1: all still out there, and sometimes you can see the 56 00:03:04,160 --> 00:03:06,799 Speaker 1: moon during the day. It always feels sort of inappropriate, though. 57 00:03:06,840 --> 00:03:08,760 Speaker 1: When you see the moon during the day, it feels 58 00:03:08,800 --> 00:03:11,560 Speaker 1: like you know you've caught somebody, like they're not supposed 59 00:03:11,560 --> 00:03:13,480 Speaker 1: to be there, Like they're tiptoeing to the fridge in 60 00:03:13,520 --> 00:03:15,519 Speaker 1: the middle of the night and you spotted them, or 61 00:03:15,560 --> 00:03:17,560 Speaker 1: like they don't know their place you know, like moon, 62 00:03:18,040 --> 00:03:21,280 Speaker 1: your place is at night, you're stepping on the Sun's toes, 63 00:03:21,600 --> 00:03:24,160 Speaker 1: and you know, it's not only the nighttime sky. That's 64 00:03:24,200 --> 00:03:27,400 Speaker 1: really fascinating, that's really amazing. That has a lot of 65 00:03:27,400 --> 00:03:29,280 Speaker 1: physics in it is what we can learn about the 66 00:03:29,360 --> 00:03:31,799 Speaker 1: nature of the universe and what's out there just by 67 00:03:31,840 --> 00:03:34,880 Speaker 1: looking up at the daytime sky. Oh well, what can 68 00:03:34,920 --> 00:03:37,600 Speaker 1: we learn? Well, one common question from kids, of course, 69 00:03:37,760 --> 00:03:41,000 Speaker 1: is why is the sky blue? You know, if the 70 00:03:41,040 --> 00:03:44,320 Speaker 1: Sun is just shining through space at us, what is 71 00:03:44,360 --> 00:03:47,480 Speaker 1: it that makes the sky blue? And so we've talked 72 00:03:47,480 --> 00:03:50,000 Speaker 1: about on the podcast a few times. It's a fascinating 73 00:03:50,040 --> 00:03:53,760 Speaker 1: interaction between the Sun's gas and the atmospheric gases. The 74 00:03:53,880 --> 00:03:56,400 Speaker 1: light that comes directly from the Sun is white light. 75 00:03:56,440 --> 00:03:58,760 Speaker 1: If you were out in space looking at the Sun, 76 00:03:58,800 --> 00:04:01,480 Speaker 1: it would mostly look why it maybe a little bit yellow, 77 00:04:01,560 --> 00:04:04,800 Speaker 1: but not all of that light passes through our atmosphere 78 00:04:04,880 --> 00:04:08,040 Speaker 1: equally well, when light hits gases in the atmosphere tends 79 00:04:08,080 --> 00:04:10,920 Speaker 1: to scatter, and it scatters more for the very high 80 00:04:11,000 --> 00:04:13,720 Speaker 1: frequency light, the blue or light, and that might make 81 00:04:13,760 --> 00:04:15,960 Speaker 1: you think, oh, well, we should see everything, but the 82 00:04:15,960 --> 00:04:18,800 Speaker 1: blue light like the blue should get reflected back into space, 83 00:04:19,200 --> 00:04:21,359 Speaker 1: and it does get reflected back into space, but it 84 00:04:21,480 --> 00:04:24,520 Speaker 1: also gets reflected down to the ground. So when you're 85 00:04:24,520 --> 00:04:26,400 Speaker 1: standing on the surface of the Earth and you're looking 86 00:04:26,560 --> 00:04:29,560 Speaker 1: up at the sky, you're seeing light that doesn't come 87 00:04:29,600 --> 00:04:31,520 Speaker 1: directly from the sun and sort of hid an atom 88 00:04:31,560 --> 00:04:34,760 Speaker 1: and bounce down to your eyeballs. So the reason that 89 00:04:34,839 --> 00:04:38,400 Speaker 1: our daytime sky is blue is because those gases bounce 90 00:04:38,480 --> 00:04:41,160 Speaker 1: the blue light down to our eyeballs. And can we 91 00:04:41,279 --> 00:04:43,520 Speaker 1: use this to figure out what the atmospheres of other 92 00:04:43,600 --> 00:04:45,839 Speaker 1: planets are made up just by looking at the color 93 00:04:45,920 --> 00:04:47,920 Speaker 1: that we see when we shine a telescope about them. 94 00:04:48,120 --> 00:04:51,440 Speaker 1: We totally can and we do exactly that. When exo 95 00:04:51,520 --> 00:04:54,960 Speaker 1: planets pass in front of their stars, the light goes 96 00:04:55,000 --> 00:04:57,479 Speaker 1: through their atmosphere and some of it bounces off and 97 00:04:57,520 --> 00:04:59,880 Speaker 1: some of it passes through, and some of it is absorbed. 98 00:05:00,040 --> 00:05:03,080 Speaker 1: It's a great way to understand what's in those exo 99 00:05:03,120 --> 00:05:05,760 Speaker 1: planet atmospheres. And so it's sort of like X raying 100 00:05:05,800 --> 00:05:08,479 Speaker 1: the atmosphere. Passing light through it is a great way 101 00:05:08,480 --> 00:05:10,839 Speaker 1: to figure out like what's there as a glow, what 102 00:05:10,880 --> 00:05:13,320 Speaker 1: does it absorbed, what does it reflect? I love the 103 00:05:13,360 --> 00:05:17,039 Speaker 1: idea of seeing a sunrise on an exo planet and 104 00:05:17,200 --> 00:05:20,240 Speaker 1: using that to figure out what's in the sky. And 105 00:05:20,240 --> 00:05:23,240 Speaker 1: you know, sunrise is on different planets all look very 106 00:05:23,320 --> 00:05:27,000 Speaker 1: different because the different planets have different atmospheres. And so 107 00:05:27,120 --> 00:05:30,160 Speaker 1: when I am looking up in the night sky recently, 108 00:05:30,160 --> 00:05:33,080 Speaker 1: I've been seeing a big red dot. Is that Mars 109 00:05:33,200 --> 00:05:35,520 Speaker 1: or is it Venus? And also when I see those colors, 110 00:05:35,560 --> 00:05:37,599 Speaker 1: is that the atmosphere I'm seeing or is that something 111 00:05:37,600 --> 00:05:39,760 Speaker 1: else that I'm seeing entirely, So, if you look up 112 00:05:39,760 --> 00:05:41,640 Speaker 1: in the night sky and you're seeing a red dot, 113 00:05:41,720 --> 00:05:44,680 Speaker 1: that's probably Mars, and Mars is definitely red. If you 114 00:05:44,680 --> 00:05:47,040 Speaker 1: were in a satellite orbiting Mars looking down, it would 115 00:05:47,040 --> 00:05:49,760 Speaker 1: look red to your eyeballs. It's not just like a 116 00:05:49,760 --> 00:05:52,560 Speaker 1: false color thing from satellite imagery that we take and 117 00:05:52,560 --> 00:05:55,720 Speaker 1: then change the way like James web Space Telescope images 118 00:05:55,760 --> 00:05:58,479 Speaker 1: are all false color. If your eyeballs were there where 119 00:05:58,560 --> 00:06:01,679 Speaker 1: James Webb Space Telescope is, you wouldn't be seeing those 120 00:06:01,720 --> 00:06:05,479 Speaker 1: images because those images are all infrared. They're all too deep, 121 00:06:05,560 --> 00:06:08,560 Speaker 1: too long wavelengths for your eyeball to even register. But 122 00:06:08,680 --> 00:06:11,400 Speaker 1: if your eyeballs were orbiting Mars, hopefully with the rest 123 00:06:11,400 --> 00:06:13,760 Speaker 1: of your body, you would see it as red. And 124 00:06:13,800 --> 00:06:16,160 Speaker 1: the reason there is not actually the atmosphere, because Mars 125 00:06:16,200 --> 00:06:20,520 Speaker 1: has almost no atmosphere. It's very very thin atmosphere. It's 126 00:06:20,560 --> 00:06:23,920 Speaker 1: because the surface of Mars itself is mostly red due 127 00:06:23,920 --> 00:06:26,440 Speaker 1: to the iron and the oxidization of it, so it's 128 00:06:26,480 --> 00:06:29,280 Speaker 1: covered in this red dust. And it's sort of amazing 129 00:06:29,320 --> 00:06:32,080 Speaker 1: that you can see it from the Earth's surface, right, 130 00:06:32,120 --> 00:06:34,599 Speaker 1: that this thing is so red that you can see 131 00:06:34,600 --> 00:06:37,679 Speaker 1: it from your backyard. That's incredible. And then the fact 132 00:06:37,680 --> 00:06:40,599 Speaker 1: that you so you said that it has very little atmosphere, 133 00:06:40,680 --> 00:06:43,200 Speaker 1: that makes me I have a pop culture question to 134 00:06:43,240 --> 00:06:46,480 Speaker 1: ask you. Someone told me that one of the things 135 00:06:46,480 --> 00:06:48,520 Speaker 1: they didn't like about the Martian was that with a 136 00:06:48,640 --> 00:06:52,040 Speaker 1: low atmosphere, if you had a big dust storm, it 137 00:06:52,040 --> 00:06:55,000 Speaker 1: wouldn't be strong enough to like knock over a rocket, 138 00:06:55,040 --> 00:06:59,400 Speaker 1: because low atmosphere means like far fewer molecules pushing against 139 00:06:59,480 --> 00:07:01,919 Speaker 1: things even in a big windstorm. So is that not 140 00:07:02,040 --> 00:07:09,120 Speaker 1: accurate about the Martian? This is this is absolutely vital stuff. Yeah, 141 00:07:09,160 --> 00:07:11,400 Speaker 1: it's definitely true that the atmosphere on Mars is very 142 00:07:11,520 --> 00:07:14,680 Speaker 1: very low, like less than one percent of the Earth's atmosphere, 143 00:07:14,760 --> 00:07:17,760 Speaker 1: and that means that the wind don't apply as much pressure, 144 00:07:18,040 --> 00:07:20,800 Speaker 1: so whin did the same velocity. For example, there just 145 00:07:20,840 --> 00:07:23,600 Speaker 1: aren't as many molecules bouncing off of you. But the 146 00:07:23,680 --> 00:07:26,680 Speaker 1: velocity can get very high, and there's also a lot 147 00:07:26,720 --> 00:07:29,360 Speaker 1: of dust in the atmosphere on Mars. You definitely do 148 00:07:29,480 --> 00:07:32,720 Speaker 1: have to worry about storms. Very high velocity windstorm on 149 00:07:32,880 --> 00:07:35,160 Speaker 1: Mars can do a lot of damage because all the 150 00:07:35,240 --> 00:07:38,600 Speaker 1: dust particles you can basically sand blast you. Right, I 151 00:07:38,600 --> 00:07:40,600 Speaker 1: don't know if the velocity is actually get high enough 152 00:07:40,600 --> 00:07:43,000 Speaker 1: to knock things over. We'll have to get Andy Weir 153 00:07:43,080 --> 00:07:45,160 Speaker 1: on the podcast and ask him that question. Well, you know, 154 00:07:45,240 --> 00:07:47,240 Speaker 1: I loved that book in that movie, and you're making 155 00:07:47,240 --> 00:07:50,800 Speaker 1: me feel better knowing that maybe that opening scene was feasible, 156 00:07:50,800 --> 00:07:52,840 Speaker 1: because I would hate to think it wasn't. But okay, 157 00:07:52,840 --> 00:07:55,200 Speaker 1: all right, let's let's get back to the important stuff. 158 00:07:55,280 --> 00:07:57,280 Speaker 1: But it does bring us to a really fascinating fact 159 00:07:57,320 --> 00:07:59,640 Speaker 1: about Mars, which is, if you're standing on the surface 160 00:07:59,640 --> 00:08:01,720 Speaker 1: of Mars Mars and you look down, of course it 161 00:08:01,720 --> 00:08:04,720 Speaker 1: looks red. But also if you look up, it looks red. 162 00:08:05,160 --> 00:08:08,160 Speaker 1: That is, the sky on Mars doesn't look blue like 163 00:08:08,240 --> 00:08:11,560 Speaker 1: it does on Earth. That's because Earth has this atmosphere 164 00:08:11,600 --> 00:08:14,080 Speaker 1: which scatters the blue light down to your eyeballs. But 165 00:08:14,200 --> 00:08:16,920 Speaker 1: Mars doesn't. This atmosphere is so thin that it doesn't 166 00:08:16,960 --> 00:08:19,400 Speaker 1: effectively scatter that light. So then why is it red 167 00:08:19,440 --> 00:08:22,640 Speaker 1: instead of like white from the sun. It's because of 168 00:08:22,640 --> 00:08:25,640 Speaker 1: all of the dust. Right, Mars doesn't have much atmosphere, 169 00:08:25,640 --> 00:08:28,200 Speaker 1: but the dust is up there, and that dust tends 170 00:08:28,240 --> 00:08:31,080 Speaker 1: to absorb blue light. That's why it looks red. Remember, 171 00:08:31,160 --> 00:08:34,960 Speaker 1: things that look a certain color, they're reflecting that color 172 00:08:35,120 --> 00:08:38,200 Speaker 1: and they're absorbing everything else. So things that are yellow 173 00:08:38,240 --> 00:08:41,480 Speaker 1: are things that reflect yellow because the yellow makes it 174 00:08:41,520 --> 00:08:44,520 Speaker 1: to your eyeball and they absorb everything else. So it 175 00:08:44,559 --> 00:08:47,560 Speaker 1: sounds weird to say that red dust absorbs blue light. 176 00:08:47,600 --> 00:08:50,360 Speaker 1: You might think that makes it blue, right, but actually 177 00:08:50,400 --> 00:08:52,800 Speaker 1: that's what makes it red. So when you look up 178 00:08:52,800 --> 00:08:55,600 Speaker 1: in the sky during the daytime on Mars, you're seeing 179 00:08:55,640 --> 00:08:58,600 Speaker 1: the red light reflected from that dust. I didn't realize 180 00:08:58,640 --> 00:09:00,920 Speaker 1: that the dust never settled enough for the sky to 181 00:09:01,000 --> 00:09:03,720 Speaker 1: not be red. That's incredible. It is incredible, And if 182 00:09:03,760 --> 00:09:07,120 Speaker 1: you're lucky enough to observe a sunset on Mars, then 183 00:09:07,160 --> 00:09:11,000 Speaker 1: you'll see an amazing blue sunset. Right. It's like totally 184 00:09:11,080 --> 00:09:14,720 Speaker 1: reversed from Earth because this dust scatters the red light, 185 00:09:15,040 --> 00:09:17,960 Speaker 1: and so if you're looking directly at the sun sort of, 186 00:09:18,080 --> 00:09:20,280 Speaker 1: then most of the red light has been scattered away 187 00:09:20,280 --> 00:09:22,199 Speaker 1: by the dust, and so the blue light is all 188 00:09:22,240 --> 00:09:25,600 Speaker 1: that survives. So you see a blue sunset on Mars 189 00:09:25,679 --> 00:09:29,280 Speaker 1: on a red sky. Oh, that's incredible. I hope within 190 00:09:29,320 --> 00:09:31,559 Speaker 1: my lifetime we get photos of that taken by an 191 00:09:31,559 --> 00:09:36,240 Speaker 1: astronaut that landed on the Martian surface. Blue sunset. Selfie, 192 00:09:36,720 --> 00:09:39,840 Speaker 1: what an Instagram pick that will be in. And that 193 00:09:39,920 --> 00:09:41,760 Speaker 1: makes you wonder, like what it would be like to 194 00:09:41,760 --> 00:09:44,400 Speaker 1: be on other planets. Right, If the atmosphere of the 195 00:09:44,440 --> 00:09:47,400 Speaker 1: planet is what determines what it looks like to be 196 00:09:47,480 --> 00:09:50,280 Speaker 1: on the planet, the color of the daytime sky and 197 00:09:50,360 --> 00:09:53,360 Speaker 1: atmospheres can be like, you know, anything that opens the 198 00:09:53,400 --> 00:09:57,160 Speaker 1: door to like having all sorts of crazy daytime colors. 199 00:09:57,160 --> 00:09:58,959 Speaker 1: You know, can you have like a yellow sky or 200 00:09:59,000 --> 00:10:03,320 Speaker 1: a purple sky or something with crazy stripes from atmospheric bands? Right, 201 00:10:03,559 --> 00:10:05,360 Speaker 1: I haven't yet seen that in a science fiction movie. 202 00:10:05,360 --> 00:10:07,480 Speaker 1: You know, somebody living on Jupiter with the sky has 203 00:10:07,520 --> 00:10:11,040 Speaker 1: like stripes of color. That would be really awesome. And 204 00:10:11,040 --> 00:10:13,440 Speaker 1: there aren't many places in the solar system where we 205 00:10:13,520 --> 00:10:16,920 Speaker 1: have had people take pictures, right. One of those, of course, 206 00:10:17,120 --> 00:10:19,920 Speaker 1: is the moon. It's something that's striking about all of 207 00:10:19,960 --> 00:10:22,880 Speaker 1: the pictures from the moon, is that the sky the 208 00:10:22,920 --> 00:10:26,280 Speaker 1: backdrop or if you look above the moon, it's always black. 209 00:10:26,600 --> 00:10:29,480 Speaker 1: And why is that right? Because you associated black with 210 00:10:29,520 --> 00:10:31,920 Speaker 1: the color of the night sky, right, But even during 211 00:10:31,960 --> 00:10:34,880 Speaker 1: the moon sort of daytime, when the sun is shining 212 00:10:35,000 --> 00:10:38,360 Speaker 1: right at you, there's nothing there to scatter the light. 213 00:10:38,559 --> 00:10:40,560 Speaker 1: So from the point of view of somebody on the moon, 214 00:10:40,720 --> 00:10:44,240 Speaker 1: the sun is just another star. So it's sort of 215 00:10:44,280 --> 00:10:48,440 Speaker 1: like a perpetual night sky with one huge, very bright 216 00:10:48,520 --> 00:10:52,760 Speaker 1: star in it half the time. Also not very invited. 217 00:10:54,480 --> 00:10:56,760 Speaker 1: You wouldn't want to have a picnic under a black sky. 218 00:10:57,080 --> 00:10:59,240 Speaker 1: I feel like the regular would get in my sandwich 219 00:10:59,240 --> 00:11:01,640 Speaker 1: and was sort of mess up the overall feeling. So 220 00:11:01,679 --> 00:11:04,040 Speaker 1: the reason the night sky in the Moon is black 221 00:11:04,240 --> 00:11:06,960 Speaker 1: is because there isn't a strong enough atmosphere there on 222 00:11:07,000 --> 00:11:09,160 Speaker 1: the Moon to scatter it to make it blue or 223 00:11:09,200 --> 00:11:11,760 Speaker 1: purple or yellow at pink polka dots. But it does 224 00:11:11,920 --> 00:11:15,720 Speaker 1: raise an interesting question and the question of today's episode, 225 00:11:15,760 --> 00:11:24,640 Speaker 1: which is does the moon have an atmosphere? So this 226 00:11:24,720 --> 00:11:26,880 Speaker 1: is a fun question because it lets us dig into 227 00:11:26,960 --> 00:11:30,280 Speaker 1: definitions and quibble about what it means to have an 228 00:11:30,280 --> 00:11:35,080 Speaker 1: atmosphere for quibbling. Sometimes it feels to me like a 229 00:11:35,080 --> 00:11:37,280 Speaker 1: big part of science is just like arguing about what 230 00:11:37,320 --> 00:11:40,440 Speaker 1: a definition is, you know, like is this really a mammal? 231 00:11:40,520 --> 00:11:42,400 Speaker 1: I don't know what lays egg? What does that mean? 232 00:11:42,559 --> 00:11:45,839 Speaker 1: Whereas really that interesting questions are like the questions behind that, 233 00:11:45,920 --> 00:11:49,360 Speaker 1: you know, like why does something with hair lay eggs? Anyway, Yeah, 234 00:11:49,440 --> 00:11:51,120 Speaker 1: that was one of the most surprising things when I 235 00:11:51,120 --> 00:11:53,560 Speaker 1: started college, was like, wait a minute, we don't even 236 00:11:53,679 --> 00:11:57,280 Speaker 1: know how to define a species really and yeah, and 237 00:11:57,480 --> 00:12:00,680 Speaker 1: of course huge arguments over that, but know it's because 238 00:12:00,920 --> 00:12:03,360 Speaker 1: nature doesn't fit in the categories that humans would like 239 00:12:03,400 --> 00:12:06,280 Speaker 1: it to. Yeah, And sometimes those arguments are just a 240 00:12:06,320 --> 00:12:08,920 Speaker 1: waste of time, people splitting hairs where there's nothing really 241 00:12:08,920 --> 00:12:12,040 Speaker 1: to be learned. But sometimes it really is illuminating because 242 00:12:12,080 --> 00:12:15,319 Speaker 1: we do try to describe the universe in terms of categories. 243 00:12:15,480 --> 00:12:18,600 Speaker 1: These ways that we like to think about things are 244 00:12:18,640 --> 00:12:21,160 Speaker 1: sort of our familiar basis, and in the end, that's 245 00:12:21,160 --> 00:12:24,560 Speaker 1: what science is, is explaining everything we'd see in terms 246 00:12:24,600 --> 00:12:28,360 Speaker 1: of things we understand. Physics is describing the unfamiliar in 247 00:12:28,480 --> 00:12:31,079 Speaker 1: terms of the familiar. So the words we're using are 248 00:12:31,120 --> 00:12:33,160 Speaker 1: sort of important. If we're going to communicate with each 249 00:12:33,200 --> 00:12:35,400 Speaker 1: other about these ideas, we better at least know what 250 00:12:35,520 --> 00:12:37,719 Speaker 1: the words mean. And I guess, to be fair, I'm 251 00:12:37,720 --> 00:12:40,760 Speaker 1: thinking that I don't exactly know what an atmosphere starts 252 00:12:40,760 --> 00:12:42,840 Speaker 1: and stops, because it seems like sort of a gradient, 253 00:12:43,080 --> 00:12:45,319 Speaker 1: like is you know at what point do you call 254 00:12:45,360 --> 00:12:48,040 Speaker 1: it an atmosphere versus something else? And so I'm not 255 00:12:48,080 --> 00:12:50,120 Speaker 1: sure that I know the answer. So let's let's see 256 00:12:50,160 --> 00:12:53,400 Speaker 1: what your listeners think. Great idea, And so as usual, 257 00:12:53,440 --> 00:12:55,840 Speaker 1: I went out there into the internet to ask people 258 00:12:55,960 --> 00:12:59,040 Speaker 1: if they thought that the moon had an atmosphere. If 259 00:12:59,120 --> 00:13:02,319 Speaker 1: you like the artists made for future episodes of the podcast, 260 00:13:02,400 --> 00:13:05,080 Speaker 1: please don't be shy. Right to me two questions at 261 00:13:05,240 --> 00:13:07,880 Speaker 1: Daniel I and Jorge dot com, and I will set 262 00:13:07,920 --> 00:13:10,120 Speaker 1: you up. Is free. It's fun. Your friends can hear 263 00:13:10,160 --> 00:13:13,640 Speaker 1: your voice on the podcast. So before you hear these answers, 264 00:13:13,679 --> 00:13:17,280 Speaker 1: think to yourself, do you think the moon has an atmosphere? 265 00:13:18,400 --> 00:13:20,800 Speaker 1: Here's what people had to say. All right, so I 266 00:13:20,840 --> 00:13:23,200 Speaker 1: don't think that our moon has an atmosphere at least 267 00:13:23,240 --> 00:13:26,840 Speaker 1: anything substantial enough to call it an atmosphere. UM. I 268 00:13:26,840 --> 00:13:28,800 Speaker 1: did have a physics professor my first year of college 269 00:13:28,840 --> 00:13:31,000 Speaker 1: who claimed to have a plan to give the Moon 270 00:13:31,000 --> 00:13:34,360 Speaker 1: atmosphere for two hundred years by basically creating an orbital 271 00:13:34,480 --> 00:13:38,240 Speaker 1: cannon that could help a smaller Moon from either Jupiter Titan. 272 00:13:38,320 --> 00:13:40,160 Speaker 1: I have like an escape glossy of seventeen miles an 273 00:13:40,160 --> 00:13:44,160 Speaker 1: hour UH to slingshot that into ours vaporize and create 274 00:13:44,160 --> 00:13:46,880 Speaker 1: an atmosphere. But it wasn't only for two years, so 275 00:13:47,000 --> 00:13:50,080 Speaker 1: I can get implaced temporary and nothing substantial enough. I 276 00:13:50,120 --> 00:13:52,199 Speaker 1: don't think the Moon has an atmosphere. I mean there 277 00:13:52,320 --> 00:13:55,840 Speaker 1: might be some like low density hydrogen or something floating around, 278 00:13:55,960 --> 00:13:59,400 Speaker 1: but not enough to call it an atmosphere. I think 279 00:14:00,080 --> 00:14:07,160 Speaker 1: has some atmosphere UM only because I'm thinking that Moon 280 00:14:07,320 --> 00:14:11,560 Speaker 1: has a weak magnetic field that might be able to 281 00:14:11,840 --> 00:14:17,680 Speaker 1: contain some kind of atmosphere. There are so not what 282 00:14:17,960 --> 00:14:21,760 Speaker 1: Earth has, but still something. UM. I would guess it 283 00:14:21,800 --> 00:14:25,040 Speaker 1: probably does. I doubt it looks anything like ours does 284 00:14:25,080 --> 00:14:26,840 Speaker 1: on Earth, but I would guess that if you're a 285 00:14:27,600 --> 00:14:30,240 Speaker 1: body or an object in the sky, and you're large 286 00:14:30,320 --> 00:14:32,640 Speaker 1: enough or dense enough that you probably attract some kind 287 00:14:32,640 --> 00:14:36,360 Speaker 1: of atmosphere. The Moon doesn't have an atmosphere. I think 288 00:14:36,400 --> 00:14:42,440 Speaker 1: it's because it's gravitational attraction is too weak to um 289 00:14:43,640 --> 00:14:46,360 Speaker 1: sort of hold the guesses around it to form an atmosphere. 290 00:14:46,720 --> 00:14:48,360 Speaker 1: So what do you think of these answers? Kelly? A 291 00:14:48,360 --> 00:14:50,600 Speaker 1: lot of skepticism here, a lot of folks feeling like 292 00:14:50,640 --> 00:14:53,200 Speaker 1: the Moon can't really have much of an atmosphere. Yeah, 293 00:14:53,440 --> 00:14:55,280 Speaker 1: but a lot of critical thinking also, a lot of 294 00:14:55,280 --> 00:14:57,960 Speaker 1: folks trying to think through like, well, you know, I 295 00:14:58,000 --> 00:15:00,320 Speaker 1: think the moon has a weak magnetic field old, so 296 00:15:00,360 --> 00:15:04,000 Speaker 1: that wouldn't contain it. And yeah, so lots of good 297 00:15:04,040 --> 00:15:07,000 Speaker 1: thinking through the problem. Absolutely, And I love seeing people 298 00:15:07,000 --> 00:15:09,800 Speaker 1: apply their knowledge of physics to this question to come 299 00:15:09,880 --> 00:15:12,200 Speaker 1: up with an answer that they think makes sense, because 300 00:15:12,200 --> 00:15:14,240 Speaker 1: if the answer is not the one that you expect, 301 00:15:14,280 --> 00:15:17,000 Speaker 1: then there better to be an explanation for it. Right, That, 302 00:15:17,160 --> 00:15:20,280 Speaker 1: in the end, is what physics is all about. That's right. 303 00:15:20,640 --> 00:15:24,400 Speaker 1: So how about we start by talking about where atmosphere 304 00:15:24,400 --> 00:15:26,920 Speaker 1: has come from? How do you get an atmosphere? Well, 305 00:15:26,960 --> 00:15:29,360 Speaker 1: you go to Amazon dot com and you just type 306 00:15:29,360 --> 00:15:31,800 Speaker 1: in whatever you'd like, and you know, they deliver it. 307 00:15:32,000 --> 00:15:34,960 Speaker 1: I know so many space space element advocates who are 308 00:15:34,960 --> 00:15:36,480 Speaker 1: going to be so excited to know it's going to 309 00:15:36,560 --> 00:15:39,880 Speaker 1: be so easy on the Moon or Mars. It's surprising, Bezos, 310 00:15:39,920 --> 00:15:42,520 Speaker 1: isn't saying more about this on Mars. Isn't the plans 311 00:15:42,640 --> 00:15:44,920 Speaker 1: just like nuke the polar ice caps? Isn't that like 312 00:15:45,000 --> 00:15:47,640 Speaker 1: step one in getting a Martian atmosphere? You know that 313 00:15:47,640 --> 00:15:50,800 Speaker 1: that has been proposed, but I'm fairly certain the international 314 00:15:50,840 --> 00:15:53,760 Speaker 1: community has mixed feelings about that proposal, so I'm not 315 00:15:53,840 --> 00:15:55,760 Speaker 1: holding my breath. And also I think it makes it 316 00:15:55,840 --> 00:15:58,520 Speaker 1: uninhabitable for quite a while. But you know, if we've 317 00:15:58,520 --> 00:16:00,840 Speaker 1: got our great grandkids in mind, maybe it's maybe it's 318 00:16:00,840 --> 00:16:02,880 Speaker 1: a good plan. Yeah, we have a whole episode on 319 00:16:03,120 --> 00:16:06,360 Speaker 1: terra forming Mars and why that plan will not work. 320 00:16:06,520 --> 00:16:09,280 Speaker 1: So we're lucky we have such a nice atmosphere here 321 00:16:09,320 --> 00:16:10,720 Speaker 1: on Earth. And I think you're right. It's a good 322 00:16:10,720 --> 00:16:13,200 Speaker 1: idea to think about why Earth has an atmosphere and 323 00:16:13,240 --> 00:16:16,480 Speaker 1: why the Moon doesn't have at least the same atmosphere 324 00:16:16,560 --> 00:16:19,000 Speaker 1: as we do. And the interesting thing is that the 325 00:16:19,040 --> 00:16:22,200 Speaker 1: Earth sort of has had a few different atmospheres. The 326 00:16:22,240 --> 00:16:24,840 Speaker 1: Earth got its first atmosphere when it was just forming. 327 00:16:24,880 --> 00:16:27,000 Speaker 1: Remember that the whole Solar system just comes from a 328 00:16:27,040 --> 00:16:30,360 Speaker 1: big cloud of gas and dust and rock and little 329 00:16:30,360 --> 00:16:33,440 Speaker 1: bits from other solar systems and stars that died. Most 330 00:16:33,480 --> 00:16:36,200 Speaker 1: of it's just hydrogen left over from the Big Bang. 331 00:16:36,360 --> 00:16:38,120 Speaker 1: But you have this big cloud of gas and dust 332 00:16:38,200 --> 00:16:40,520 Speaker 1: in space, you have some blobs in it that are 333 00:16:40,520 --> 00:16:43,280 Speaker 1: a little denser than others, so they have stronger gravity. 334 00:16:43,480 --> 00:16:46,520 Speaker 1: They are pulling everything together, and that's the formation of 335 00:16:46,560 --> 00:16:49,040 Speaker 1: the Solar system. Of course, in the very center is 336 00:16:49,080 --> 00:16:51,520 Speaker 1: the Sun, which gathers in most of the gas and 337 00:16:51,560 --> 00:16:54,400 Speaker 1: the dust. But you also have other little blobs which 338 00:16:54,400 --> 00:16:57,320 Speaker 1: eventually formed planets, and they try to gather as much 339 00:16:57,320 --> 00:16:59,880 Speaker 1: stuff as they can before the Sun gobbles it all up. 340 00:17:00,000 --> 00:17:02,920 Speaker 1: You know. It's funny my intuition, and this is why 341 00:17:02,920 --> 00:17:05,679 Speaker 1: I didn't become a physicist. My intuition, Like, it feels 342 00:17:05,680 --> 00:17:09,240 Speaker 1: to me like gases shouldn't get pulled in by gravity, 343 00:17:09,280 --> 00:17:12,280 Speaker 1: but of course they are, and they should. But the 344 00:17:12,320 --> 00:17:15,919 Speaker 1: idea that gravity is holding our atmosphere on, I don't know. 345 00:17:15,960 --> 00:17:17,760 Speaker 1: It feels like the little molecule should be able to 346 00:17:17,800 --> 00:17:20,200 Speaker 1: just pop out in escape. But I'm glad that I'm 347 00:17:20,200 --> 00:17:22,280 Speaker 1: wrong about it. You're not actually wrong A lot of 348 00:17:22,320 --> 00:17:25,200 Speaker 1: them do escape, and the Earth is constantly boiling off 349 00:17:25,280 --> 00:17:28,840 Speaker 1: its atmosphere into space. It's a tenuous balance, right, The 350 00:17:28,880 --> 00:17:30,760 Speaker 1: Earth is pulling on those little guys, but they are 351 00:17:30,800 --> 00:17:33,879 Speaker 1: moving quickly, and the ones that have higher velocity and 352 00:17:34,040 --> 00:17:37,639 Speaker 1: higher altitudes definitely do escape. And in the very early 353 00:17:37,720 --> 00:17:40,160 Speaker 1: days of the Solar System, the Earth had an atmosphere 354 00:17:40,200 --> 00:17:43,560 Speaker 1: which came from these primordial gases, the hydrogen helium that 355 00:17:43,640 --> 00:17:46,080 Speaker 1: was just sort of like around, but it didn't last 356 00:17:46,119 --> 00:17:48,159 Speaker 1: for very long. It's not a very good atmosphere for 357 00:17:48,200 --> 00:17:51,000 Speaker 1: having an atmosphere, I guess you could say, because first 358 00:17:51,000 --> 00:17:52,800 Speaker 1: of all, the Sun was gobbling up most of the 359 00:17:52,880 --> 00:17:55,560 Speaker 1: hydrogen and the helium, and then once the Sun formed, 360 00:17:55,640 --> 00:17:58,639 Speaker 1: it was producing a lot of radiation which stripped the 361 00:17:58,640 --> 00:18:02,119 Speaker 1: inner planets of theirmosphere. So like solar wind and heat 362 00:18:02,400 --> 00:18:06,239 Speaker 1: from the Sun basically blasted the Earth's atmosphere away. So 363 00:18:06,240 --> 00:18:09,160 Speaker 1: it started off having a scoop of hygen and helium 364 00:18:09,160 --> 00:18:11,160 Speaker 1: and stuff that could have made an atmosphere, but then 365 00:18:11,160 --> 00:18:14,439 Speaker 1: it got blasted dry basically by the early Sun. So 366 00:18:14,680 --> 00:18:18,639 Speaker 1: is solar wind well named? Is it like the sun 367 00:18:18,920 --> 00:18:22,320 Speaker 1: is like and the stuff just sort of blows away? 368 00:18:22,480 --> 00:18:25,240 Speaker 1: Or is it more like the photons that come out 369 00:18:25,280 --> 00:18:27,679 Speaker 1: from the Sun. It's like a billiard table, and it 370 00:18:27,800 --> 00:18:30,159 Speaker 1: like knocks the hydrogen in the helium out of our 371 00:18:30,200 --> 00:18:32,800 Speaker 1: atmosphere when they like bounce into each other. I think 372 00:18:32,800 --> 00:18:36,960 Speaker 1: it's pretty well named because it's not just photons. It's protons, 373 00:18:37,040 --> 00:18:40,000 Speaker 1: it's electrons, it's actual particles. So if you think about 374 00:18:40,000 --> 00:18:43,480 Speaker 1: wind on Earth, it's like high moving particles that carry 375 00:18:43,520 --> 00:18:46,000 Speaker 1: momentum and it can push stuff over, and the solar 376 00:18:46,040 --> 00:18:49,000 Speaker 1: wind is really the same thing. It's stuff, it's matter 377 00:18:49,080 --> 00:18:52,119 Speaker 1: particles carrying momentum, and it could like push a solar sail, 378 00:18:52,480 --> 00:18:55,399 Speaker 1: and it definitely blasts things off of the Moon and 379 00:18:55,560 --> 00:18:58,240 Speaker 1: Mars and early Earth. Way to go, phus. This good 380 00:18:58,280 --> 00:19:01,000 Speaker 1: job name in that thing. And that's one reason why 381 00:19:01,040 --> 00:19:03,679 Speaker 1: you have, for example, rocky planets in the interior of 382 00:19:03,680 --> 00:19:06,000 Speaker 1: the Solar system, because that's the kind of stuff the 383 00:19:06,040 --> 00:19:09,800 Speaker 1: Sun couldn't blast off and like formed dense or blobs. 384 00:19:10,080 --> 00:19:11,919 Speaker 1: And in the outer part of the Solar system you 385 00:19:11,960 --> 00:19:14,520 Speaker 1: have the gas giants because they were far enough away 386 00:19:14,520 --> 00:19:16,560 Speaker 1: from the Sun to get to gobble up some of 387 00:19:16,560 --> 00:19:19,120 Speaker 1: their own gas and to hold onto it out there 388 00:19:19,119 --> 00:19:22,040 Speaker 1: where the solar radiation is weaker, So we got amosphere 389 00:19:22,119 --> 00:19:24,480 Speaker 1: very early on, and so did the Moon. As the 390 00:19:24,520 --> 00:19:28,119 Speaker 1: moon form from whatever primordial blobs made it. It also 391 00:19:28,200 --> 00:19:31,280 Speaker 1: must have had some helium and some hydrogen, but that 392 00:19:31,359 --> 00:19:34,240 Speaker 1: also was blasted clean by the Sun. So we both 393 00:19:34,280 --> 00:19:37,520 Speaker 1: started with an atmosphere and both lost our atmosphere very quickly, 394 00:19:37,640 --> 00:19:40,119 Speaker 1: and we both both of them lost it entirely or 395 00:19:40,119 --> 00:19:42,840 Speaker 1: did Earth retain some of it almost entirely, I mean 396 00:19:43,119 --> 00:19:45,880 Speaker 1: never completely dry. There must have been a little bit 397 00:19:45,880 --> 00:19:48,399 Speaker 1: of hydrogen floating around, but compared to the densities we 398 00:19:48,400 --> 00:19:51,800 Speaker 1: have today basically zero. Okay, Well, before we get into 399 00:19:51,840 --> 00:20:08,080 Speaker 1: what our second atmosphere was, like, let's take a break. Okay, 400 00:20:08,119 --> 00:20:12,639 Speaker 1: So the first atmosphere we had and we lost, but 401 00:20:12,760 --> 00:20:15,240 Speaker 1: we know that we get to hold onto one atmosphere eventually, 402 00:20:15,560 --> 00:20:18,080 Speaker 1: So what happens to the next atmosphere? This is like 403 00:20:18,119 --> 00:20:20,359 Speaker 1: a Disney movie. You know, there's a happy ending, right, 404 00:20:20,400 --> 00:20:22,760 Speaker 1: So even when there's ups and downs, you can sort 405 00:20:22,760 --> 00:20:26,000 Speaker 1: of hold on, just like life. Right. But we're telling 406 00:20:26,040 --> 00:20:29,280 Speaker 1: two stories simultaneously here. We're interested in whether the Moon 407 00:20:29,400 --> 00:20:31,439 Speaker 1: has an atmosphere, and we're telling the story of the 408 00:20:31,480 --> 00:20:34,359 Speaker 1: Earth and the Moon's atmosphere. Is in parallel to see 409 00:20:34,400 --> 00:20:37,199 Speaker 1: why they have different fates. So the Earth's got its 410 00:20:37,240 --> 00:20:40,160 Speaker 1: atmosphere is sort of rebooted from its interior. You had 411 00:20:40,160 --> 00:20:42,919 Speaker 1: like volcanoes and all sorts of crazy stuff happening on 412 00:20:42,960 --> 00:20:46,080 Speaker 1: the surface of the Earth which outgased like water and 413 00:20:46,200 --> 00:20:50,000 Speaker 1: CEO two and sulfur dioxide and nitrogen. So this is 414 00:20:50,040 --> 00:20:53,280 Speaker 1: like the Earth burping and giving itself an atmosphere just 415 00:20:53,440 --> 00:20:58,240 Speaker 1: from those burps. That makes it like substantially less beautiful 416 00:20:58,280 --> 00:21:01,760 Speaker 1: to watch the sunset. All those are Earth burps making 417 00:21:01,760 --> 00:21:04,240 Speaker 1: those colors. Yeah, and you know, let's go with burps 418 00:21:04,280 --> 00:21:06,800 Speaker 1: rather than any sort of other gaseous emission. But it's 419 00:21:06,840 --> 00:21:09,960 Speaker 1: incredible that there must have been so many volcanoes, so 420 00:21:10,040 --> 00:21:12,560 Speaker 1: much sort of tectonic action in the early Earth, that 421 00:21:12,640 --> 00:21:16,159 Speaker 1: you could release vast quantities of gas. Right. Did this 422 00:21:16,200 --> 00:21:18,439 Speaker 1: happen on Mars too? Or am I getting too far 423 00:21:18,480 --> 00:21:21,560 Speaker 1: afield by asking that because Morris has volcanoes too, Right, Yeah, 424 00:21:21,640 --> 00:21:23,520 Speaker 1: we think it happened on a lot of these planets. 425 00:21:23,720 --> 00:21:26,160 Speaker 1: And remember the scale though of the atmosphere. Even though 426 00:21:26,200 --> 00:21:28,840 Speaker 1: it seems vast to us and it seems dense, it's 427 00:21:28,840 --> 00:21:31,440 Speaker 1: really a very very thin layer on top of an 428 00:21:31,640 --> 00:21:35,439 Speaker 1: enormous sphere. Atmosphere goes up like a few hundred kilometers 429 00:21:35,480 --> 00:21:38,040 Speaker 1: depending on how you define it. But the Earth's radius 430 00:21:38,119 --> 00:21:42,080 Speaker 1: is six thousand kilometers, and so it's not that surprising 431 00:21:42,119 --> 00:21:45,479 Speaker 1: that all of that stuff could bubble up enough gas 432 00:21:45,520 --> 00:21:48,000 Speaker 1: to cover it with a very thin shell. It happened 433 00:21:48,040 --> 00:21:50,000 Speaker 1: on Earth, and it happened on Mars, and we also 434 00:21:50,040 --> 00:21:52,840 Speaker 1: think it might have happened on the Moon. The Moon 435 00:21:53,080 --> 00:21:56,000 Speaker 1: is not just like a lifeless, inert, frozen rock. It 436 00:21:56,160 --> 00:21:58,840 Speaker 1: had volcanoes. We can see this on the surface of 437 00:21:58,880 --> 00:22:01,960 Speaker 1: the Moon. There are all lava planes underneath the Moon. 438 00:22:02,000 --> 00:22:05,240 Speaker 1: There are these lava tubes, all sorts of crazy volcanic 439 00:22:05,280 --> 00:22:07,680 Speaker 1: stuff that happened on the Moon. How long ago did 440 00:22:07,720 --> 00:22:10,920 Speaker 1: the volcanic activity end, We don't know, and we don't 441 00:22:10,920 --> 00:22:13,480 Speaker 1: think that there are any active volcanoes right now. But 442 00:22:13,560 --> 00:22:16,960 Speaker 1: we have measured moon quakes, like you put these sensors 443 00:22:17,000 --> 00:22:19,720 Speaker 1: on the surface of the Moon and there are moon quakes, 444 00:22:19,840 --> 00:22:23,000 Speaker 1: right and that suggests, yeah, that there's stuff going on 445 00:22:23,160 --> 00:22:25,919 Speaker 1: inside the Moon, that there's internal magma, this stuff like 446 00:22:25,960 --> 00:22:28,679 Speaker 1: splashing around in there, which might mean you know, a 447 00:22:28,720 --> 00:22:31,920 Speaker 1: future volcanic action. Probably not, though across is probably now 448 00:22:32,000 --> 00:22:34,440 Speaker 1: cooled and sealed, and all that stuff is sunk too 449 00:22:34,440 --> 00:22:37,440 Speaker 1: far towards the center to ever crop up again. Will 450 00:22:37,480 --> 00:22:41,720 Speaker 1: it cool and stop moonquaking at some point? Eventually? Probably will. Yeah, 451 00:22:41,760 --> 00:22:44,359 Speaker 1: the same sort of thing is happening on Mars. Mars 452 00:22:44,400 --> 00:22:46,960 Speaker 1: and the Moon of course much much smaller than the Earth, 453 00:22:47,000 --> 00:22:49,320 Speaker 1: and so they cool faster. And we think, for example, 454 00:22:49,359 --> 00:22:52,280 Speaker 1: Mars still has some sort of liquid or at least 455 00:22:52,359 --> 00:22:54,960 Speaker 1: fluid core, and there's stuff going on inside there, because 456 00:22:54,960 --> 00:22:57,720 Speaker 1: we have measured Mars quakes as well. But there isn't 457 00:22:57,760 --> 00:23:01,439 Speaker 1: active volcanism on the Moon or on Mars, okay. And 458 00:23:01,520 --> 00:23:05,479 Speaker 1: so did the Moon lose its second atmosphere for the 459 00:23:05,520 --> 00:23:07,680 Speaker 1: same reason that it lost its first, or did the 460 00:23:07,720 --> 00:23:11,080 Speaker 1: volcanoes never give it an atmosphere to begin with? Yeah, 461 00:23:11,080 --> 00:23:13,400 Speaker 1: it's a great question. And so we have to understand 462 00:23:13,440 --> 00:23:15,840 Speaker 1: not just how you get an atmosphere, but how you 463 00:23:15,920 --> 00:23:18,840 Speaker 1: hold onto it right. It's not enough to just produce 464 00:23:18,880 --> 00:23:21,679 Speaker 1: the gases either from the first scoop of Solar system 465 00:23:21,760 --> 00:23:25,480 Speaker 1: stuff or remaking it again from volcanoes. You gotta hold 466 00:23:25,600 --> 00:23:28,440 Speaker 1: onto it right, because, as you say, there are things 467 00:23:28,480 --> 00:23:30,199 Speaker 1: out there in the Solar System that are trying to 468 00:23:30,240 --> 00:23:33,200 Speaker 1: get rid of your atmosphere, and so the solar wind 469 00:23:33,240 --> 00:23:35,840 Speaker 1: didn't stop, right. The solar wind was around in the 470 00:23:35,880 --> 00:23:38,720 Speaker 1: early days when things were forming, and it's still going 471 00:23:38,840 --> 00:23:42,639 Speaker 1: on today. And so their processes out there which remove atmospheres, 472 00:23:42,640 --> 00:23:46,600 Speaker 1: which work against having an atmosphere on the Earth and 473 00:23:46,880 --> 00:23:50,160 Speaker 1: on the Moon and on Mars. So this second atmosphere 474 00:23:50,200 --> 00:23:53,960 Speaker 1: that the Moon did have, unfortunately did get blown away. Sorry. Moon. 475 00:23:54,240 --> 00:23:58,280 Speaker 1: The story always seems so sad for the Moon. But 476 00:23:58,359 --> 00:24:00,840 Speaker 1: I think it's really interesting to understand sort of the 477 00:24:00,880 --> 00:24:04,119 Speaker 1: balance between those effects. I like thinking about it microscopically 478 00:24:04,160 --> 00:24:06,639 Speaker 1: the way you were. I think about the atmosphere and 479 00:24:06,760 --> 00:24:10,320 Speaker 1: individual particles of that gas, right, because in the end, 480 00:24:10,320 --> 00:24:13,440 Speaker 1: the atmosphere is not just like a huge blob of gas. 481 00:24:13,560 --> 00:24:16,760 Speaker 1: It really is made of individual particles. And the fate 482 00:24:16,800 --> 00:24:19,560 Speaker 1: of those individual particles is what determines the fade of 483 00:24:19,600 --> 00:24:21,720 Speaker 1: the atmosphere. And it's sort of weird to think about, 484 00:24:21,720 --> 00:24:26,560 Speaker 1: but gravity does operate on like individual atoms of gas, right, 485 00:24:26,600 --> 00:24:30,320 Speaker 1: Like the Earth pulls on each of those nitrogen atoms 486 00:24:30,320 --> 00:24:33,600 Speaker 1: and each of those oxygen atoms. It really is yanking 487 00:24:33,600 --> 00:24:36,000 Speaker 1: and keeping a lot of them on the surface. Of 488 00:24:36,040 --> 00:24:38,719 Speaker 1: the Earth, and that's of course, the biggest difference between 489 00:24:38,720 --> 00:24:41,719 Speaker 1: the Earth and the Moon is that the Earth is bigger, 490 00:24:41,800 --> 00:24:44,200 Speaker 1: it has more gravity, and it's a lot of our 491 00:24:44,200 --> 00:24:47,159 Speaker 1: listeners said, the Moon just doesn't have the gravity to 492 00:24:47,280 --> 00:24:50,840 Speaker 1: hold onto its atmosphere. Does the magnetosphere player roll too 493 00:24:50,920 --> 00:24:53,119 Speaker 1: or is it mostly about gravity. That's a really interesting 494 00:24:53,119 --> 00:24:56,760 Speaker 1: topic because the Earth's magnetic field does protect us from 495 00:24:56,800 --> 00:24:59,959 Speaker 1: the solar wind. Right, the solar wind are charged particle, 496 00:25:00,119 --> 00:25:03,280 Speaker 1: These are protons, these are electrons. What happens when a 497 00:25:03,359 --> 00:25:05,880 Speaker 1: charge particle hits a magnetic field is that it tends 498 00:25:05,920 --> 00:25:08,320 Speaker 1: to bend. And so when charge particles from the Sun 499 00:25:08,480 --> 00:25:11,680 Speaker 1: hit our magnetic field, they don't immediately just like slam 500 00:25:11,720 --> 00:25:15,320 Speaker 1: into our atmosphere. They spiral around these magnetic field lines, 501 00:25:15,359 --> 00:25:17,520 Speaker 1: and they go up to the north pole or down 502 00:25:17,560 --> 00:25:20,160 Speaker 1: to the south pole, and you finally see them as 503 00:25:20,200 --> 00:25:22,760 Speaker 1: like the Northern lights or the Southern lights. That's what 504 00:25:22,880 --> 00:25:26,440 Speaker 1: causes them, this magnetic field, and so initially you think, oh, well, 505 00:25:26,480 --> 00:25:29,320 Speaker 1: this must protect us. It's like a shield keeping our 506 00:25:29,359 --> 00:25:32,800 Speaker 1: atmosphere in place. That's sort of the prevailing view that 507 00:25:32,880 --> 00:25:36,320 Speaker 1: a big magnetic field will protect you like a shield. 508 00:25:36,400 --> 00:25:38,960 Speaker 1: But other people feel like, actually, a magnetic field is 509 00:25:39,000 --> 00:25:41,359 Speaker 1: sort of like a sale. It's going to capture a 510 00:25:41,400 --> 00:25:44,120 Speaker 1: lot of solar wind and funnel it into the planet, 511 00:25:44,160 --> 00:25:47,080 Speaker 1: helping strip the atmosphere, and so, like most things that 512 00:25:47,080 --> 00:25:50,680 Speaker 1: involved like more than one particle, the story is complicated 513 00:25:50,720 --> 00:25:53,000 Speaker 1: and people have differing opinions about it. But in the 514 00:25:53,040 --> 00:25:56,080 Speaker 1: case of the Moon, this very very little magnetic field there. 515 00:25:56,359 --> 00:25:59,440 Speaker 1: Like the Moon, we don't think has enough internal motion 516 00:25:59,640 --> 00:26:02,200 Speaker 1: in its core to generate a strong magnetic field. There 517 00:26:02,240 --> 00:26:04,480 Speaker 1: are magnetic rocks on the surface of the Moon, but 518 00:26:04,560 --> 00:26:07,760 Speaker 1: has no like big overall magnetic field to shield it 519 00:26:07,840 --> 00:26:10,240 Speaker 1: or to act like a sale. Are those magnetic rocks 520 00:26:10,320 --> 00:26:13,040 Speaker 1: big enough that you could try to address the question 521 00:26:13,080 --> 00:26:16,280 Speaker 1: about whether magnetic fields help or hurt atmospheres or no, 522 00:26:16,320 --> 00:26:18,359 Speaker 1: because there's just no atmosphere on the Moon, so you 523 00:26:18,400 --> 00:26:21,840 Speaker 1: can't compare like the area around magnetic rocks versus the 524 00:26:21,880 --> 00:26:24,760 Speaker 1: area around non magnetic rocks. Yeah, in order to operate 525 00:26:24,800 --> 00:26:26,359 Speaker 1: like a shield, I think you really do need to 526 00:26:26,359 --> 00:26:29,879 Speaker 1: have a planet sized magnetic field, um, and there just 527 00:26:30,040 --> 00:26:31,840 Speaker 1: isn't a coherent one on the Moon. I mean, if 528 00:26:31,840 --> 00:26:35,160 Speaker 1: you map the Moon's surface for magnetism, and they've done 529 00:26:35,200 --> 00:26:37,760 Speaker 1: that you do identify some spots with more magnetic field 530 00:26:37,800 --> 00:26:40,199 Speaker 1: or less. That's more probe of like what kind of 531 00:26:40,240 --> 00:26:43,200 Speaker 1: metals are there just under the surface, rather than telling 532 00:26:43,240 --> 00:26:45,840 Speaker 1: you anything about the planet's atmosphere. Arts was that the 533 00:26:46,000 --> 00:26:49,479 Speaker 1: end of our atmosphere story? Or is there a third phase? 534 00:26:49,800 --> 00:26:52,680 Speaker 1: So the Earth's atmosphere did keep evolving. Of course, now 535 00:26:52,680 --> 00:26:55,480 Speaker 1: we have oxygen in the Earth's atmosphere, which didn't come 536 00:26:55,520 --> 00:26:58,840 Speaker 1: from those volcanoes, right, That actually mostly came from life 537 00:26:58,840 --> 00:27:02,600 Speaker 1: when little cells begin into drink sunlight and do photosynthesis. 538 00:27:02,760 --> 00:27:05,880 Speaker 1: They turned a lot of the atmosphere into oxygen, though 539 00:27:05,920 --> 00:27:08,520 Speaker 1: surprisingly it took a long time. Right, You can't just 540 00:27:08,600 --> 00:27:11,440 Speaker 1: pump oxygen into the atmosphere and have it to stay 541 00:27:11,440 --> 00:27:14,840 Speaker 1: there because oxygen is so reactive. Most of the oxygen 542 00:27:14,880 --> 00:27:17,720 Speaker 1: that was produced by life actually got gobbled up by 543 00:27:17,880 --> 00:27:21,080 Speaker 1: rocks because rocks like to get oxydized. So if you 544 00:27:21,119 --> 00:27:24,760 Speaker 1: put oxygen in your atmosphere, it will weather. The rocks 545 00:27:25,080 --> 00:27:27,919 Speaker 1: are the surface of your planet will get like rusty, 546 00:27:28,000 --> 00:27:30,840 Speaker 1: for example, and that gobbles up a lot of the oxygen. 547 00:27:31,000 --> 00:27:33,440 Speaker 1: So it took hundreds of millions of years of pumping 548 00:27:33,480 --> 00:27:35,760 Speaker 1: oxygen into the atmosphere of the Earth before it had 549 00:27:35,800 --> 00:27:39,720 Speaker 1: like a measurable impact on what actually was in the atmosphere. 550 00:27:39,800 --> 00:27:45,440 Speaker 1: And today the Earth's atmosphere is mostly nitrogen. It's like oxygen, 551 00:27:45,720 --> 00:27:48,639 Speaker 1: and then like one percent argon point oh three percent 552 00:27:48,800 --> 00:27:51,199 Speaker 1: c O two and rising, and then a bunch of 553 00:27:51,200 --> 00:27:53,840 Speaker 1: other stuff. But the Moon, of course doesn't have life 554 00:27:53,880 --> 00:27:55,720 Speaker 1: on it, and it didn't have and it wasn't able 555 00:27:55,760 --> 00:27:58,240 Speaker 1: to keep that atmosphere around, and so it didn't get 556 00:27:58,240 --> 00:28:00,840 Speaker 1: to have the third act of its atmosphere. And is 557 00:28:00,880 --> 00:28:05,800 Speaker 1: there like a physics definition for when your atmosphere ends? 558 00:28:06,119 --> 00:28:10,119 Speaker 1: Is it like, you know, all what exactly kilometers the 559 00:28:10,200 --> 00:28:12,760 Speaker 1: atmosphere ends, or is it like a gradient where you 560 00:28:12,840 --> 00:28:14,520 Speaker 1: just have a little bit less and less as you 561 00:28:14,520 --> 00:28:17,120 Speaker 1: go and there's no clear cut off point. It's totally 562 00:28:17,160 --> 00:28:20,520 Speaker 1: a gradient. And there are definitions and they all disagree 563 00:28:20,520 --> 00:28:22,440 Speaker 1: with each other. You know. Some people say, oh, a 564 00:28:22,520 --> 00:28:25,440 Speaker 1: hundred kilometers, some people say no, the threshold should be 565 00:28:25,480 --> 00:28:28,359 Speaker 1: sixty five kilometers, and people argue endlessly about it, and 566 00:28:28,400 --> 00:28:31,360 Speaker 1: I'm not sure that we're really learning anything through that argument. 567 00:28:31,400 --> 00:28:34,040 Speaker 1: There are some interesting distinctions, like the Earth's atmosphere is 568 00:28:34,080 --> 00:28:38,000 Speaker 1: mostly within thirty kilometers of the surface, it's like of 569 00:28:38,000 --> 00:28:39,800 Speaker 1: the mass of the atmosphere. But you know, you could 570 00:28:39,840 --> 00:28:42,880 Speaker 1: draw that threshold anywhere, you could say nine or ninety 571 00:28:42,960 --> 00:28:44,840 Speaker 1: nine nine percent. In order to get all of it, 572 00:28:44,880 --> 00:28:47,720 Speaker 1: you have to go out like ridiculously far, you know, 573 00:28:47,800 --> 00:28:50,400 Speaker 1: hundreds of thousands of kilometers to say this is the 574 00:28:50,480 --> 00:28:53,040 Speaker 1: full envelope of the Earth. But there is an interesting 575 00:28:53,040 --> 00:28:56,880 Speaker 1: transition above a certain distance, the density is so low 576 00:28:57,200 --> 00:28:59,800 Speaker 1: that the atoms don't really bump into each other, and 577 00:28:59,800 --> 00:29:03,600 Speaker 1: so above what we call the atmosphere something called the exosphere, 578 00:29:03,760 --> 00:29:05,840 Speaker 1: where the density is so low that adams can travel 579 00:29:05,880 --> 00:29:09,320 Speaker 1: for like hundreds of kilometers without bouncing into each other. 580 00:29:09,360 --> 00:29:11,320 Speaker 1: So the dynamics of it are a little bit different. 581 00:29:11,320 --> 00:29:14,840 Speaker 1: It's collision lists. So usually where we get to by 582 00:29:14,840 --> 00:29:18,400 Speaker 1: the end of the episode, is you telling me something awful? 583 00:29:18,960 --> 00:29:22,160 Speaker 1: So now you've got me wondering is Earth going to 584 00:29:22,240 --> 00:29:26,560 Speaker 1: lose its atmosphere? So can you tell me about the ways, 585 00:29:26,560 --> 00:29:29,760 Speaker 1: like summarized for me, the ways that atmosphere gets lost, 586 00:29:30,320 --> 00:29:33,400 Speaker 1: and then is Earth gonna lose the atmosphere? Because probably 587 00:29:33,440 --> 00:29:37,840 Speaker 1: that's where this conversation is going. Right, your kids are 588 00:29:37,840 --> 00:29:40,680 Speaker 1: going to be fine, Kelly. Now, their kids and their 589 00:29:40,800 --> 00:29:42,600 Speaker 1: kids kids. You know, they're gonna have to listen to 590 00:29:42,640 --> 00:29:45,800 Speaker 1: the next generation of the podcast to find out. But 591 00:29:45,880 --> 00:29:48,360 Speaker 1: I think it's really fascinating to think about the dynamic 592 00:29:48,440 --> 00:29:51,400 Speaker 1: processes here and the things that are changing. The solar system. 593 00:29:51,720 --> 00:29:53,920 Speaker 1: We usually think of the solar system is so static. 594 00:29:53,960 --> 00:29:56,120 Speaker 1: It's just like this is the way it's been. It's 595 00:29:56,120 --> 00:29:59,040 Speaker 1: been this way for thousands or millions or maybe billions 596 00:29:59,080 --> 00:30:01,840 Speaker 1: of years, and so probably has always been this way, 597 00:30:02,280 --> 00:30:04,560 Speaker 1: and so there's always a little bit shocking and surprising 598 00:30:04,600 --> 00:30:07,800 Speaker 1: to discover that things are dynamic, that things are changing. 599 00:30:07,920 --> 00:30:10,200 Speaker 1: And the atmosphere is definitely in that category because it 600 00:30:10,320 --> 00:30:12,840 Speaker 1: is pretty tenuous. You know, it's not easy to hold 601 00:30:12,880 --> 00:30:15,200 Speaker 1: onto these gases, and there are a lot of factors 602 00:30:15,240 --> 00:30:17,120 Speaker 1: that are helped blowing it away. So we talked about 603 00:30:17,120 --> 00:30:19,640 Speaker 1: the solar wind. You know, something that people don't really appreciate, 604 00:30:19,720 --> 00:30:22,040 Speaker 1: I think is that the solar wind comes in like 605 00:30:22,120 --> 00:30:26,640 Speaker 1: a million miles per hour, these particles coming from the Sun. Yeah, 606 00:30:26,720 --> 00:30:29,880 Speaker 1: there's a bit along, right, and so like point one 607 00:30:30,040 --> 00:30:33,000 Speaker 1: five percent of the speed of light. It sounds like 608 00:30:33,040 --> 00:30:35,600 Speaker 1: a low value, but it's really really high. And nobody 609 00:30:35,640 --> 00:30:37,560 Speaker 1: wants to get shot at in the face with a 610 00:30:37,560 --> 00:30:41,040 Speaker 1: proton at a million miles per hour, I'll pass. And 611 00:30:41,080 --> 00:30:43,440 Speaker 1: even if we didn't have the Sun trying to strip 612 00:30:43,520 --> 00:30:46,600 Speaker 1: us of our atmosphere, right, it does just boil away. 613 00:30:46,680 --> 00:30:49,080 Speaker 1: There's gravity is powerful, but at the upper edges of 614 00:30:49,120 --> 00:30:51,840 Speaker 1: the atmosphere there are fast moving particles and they can 615 00:30:51,920 --> 00:30:54,440 Speaker 1: just achieve escape velocity. You know, you have a particle 616 00:30:54,560 --> 00:30:57,680 Speaker 1: going fast enough, pointed in the right direction, it's just gone. 617 00:30:58,080 --> 00:30:59,920 Speaker 1: You know, you don't have to launch it into out 618 00:31:00,000 --> 00:31:02,840 Speaker 1: of space. It's just hot and fast moving and it's 619 00:31:02,880 --> 00:31:07,040 Speaker 1: just taken off. And so this definitely happens for every planet, 620 00:31:07,040 --> 00:31:09,760 Speaker 1: and it happens also for Earth. No heavier planets is 621 00:31:09,800 --> 00:31:12,640 Speaker 1: gonna lose less because the escape velocity is higher. But 622 00:31:12,680 --> 00:31:16,280 Speaker 1: if you have lower mass gases like hydrogen and helium, 623 00:31:16,640 --> 00:31:19,800 Speaker 1: then they just boil off. Does it get replenished. It 624 00:31:19,840 --> 00:31:23,400 Speaker 1: doesn't really get replenished by new hydrogen or helium or oxygen. 625 00:31:23,680 --> 00:31:26,040 Speaker 1: That we do get a lot of space dust every year, 626 00:31:26,320 --> 00:31:28,960 Speaker 1: and so we get like tons of space dust, just 627 00:31:29,040 --> 00:31:32,920 Speaker 1: like debris falling to Earth, and we're also losing our atmosphere. 628 00:31:33,040 --> 00:31:37,560 Speaker 1: We lose three kilograms per second of hydrogen. That sounds 629 00:31:37,640 --> 00:31:41,560 Speaker 1: kind of scary, Okay, but we'll probably be fine. We're 630 00:31:41,560 --> 00:31:45,120 Speaker 1: gonna be fine for about a billion years until the Sun, 631 00:31:45,440 --> 00:31:48,120 Speaker 1: when it's gonna be like ten brighter than it is now, 632 00:31:48,360 --> 00:31:49,960 Speaker 1: is going to make it hot enough on Earth for 633 00:31:50,000 --> 00:31:52,720 Speaker 1: the oceans to boil, for water to break down into 634 00:31:52,800 --> 00:31:55,560 Speaker 1: hydrogen oxygen, and the Earth will probably lose a lot 635 00:31:55,600 --> 00:31:59,640 Speaker 1: of that hydrogen. Time to invest in interstellar travel, all right. 636 00:32:00,440 --> 00:32:02,560 Speaker 1: You know that news isn't as bad as some of 637 00:32:02,600 --> 00:32:04,760 Speaker 1: the news that you've delivered to me, But I still 638 00:32:04,800 --> 00:32:06,160 Speaker 1: think that we should take a break so that I 639 00:32:06,160 --> 00:32:21,479 Speaker 1: can recover for a moment. We'll be back soon. Okay, 640 00:32:21,520 --> 00:32:24,720 Speaker 1: we're back. Recap for me what we know about the 641 00:32:24,720 --> 00:32:27,880 Speaker 1: Moon's atmosphere. So we think that the Moon probably did 642 00:32:28,040 --> 00:32:31,520 Speaker 1: get a delivery of gas early on, right from the 643 00:32:31,560 --> 00:32:34,800 Speaker 1: primordial soup, and then it may have also gotten the 644 00:32:34,880 --> 00:32:38,720 Speaker 1: refreshing of its gas from volcanism. But we don't think 645 00:32:38,720 --> 00:32:41,880 Speaker 1: that there's much atmosphere there today, and the reason is 646 00:32:41,920 --> 00:32:44,920 Speaker 1: that it just doesn't have the mass to hold onto. 647 00:32:44,920 --> 00:32:47,560 Speaker 1: The stuff doesn't have the magnetic feel. So if you 648 00:32:47,800 --> 00:32:50,400 Speaker 1: ordered a new atmosphere for the Moon, if you like 649 00:32:50,440 --> 00:32:53,200 Speaker 1: went up there and pumped a bunch of oxygen and 650 00:32:53,320 --> 00:32:55,840 Speaker 1: nitrogen and c O two onto the Moon. Most of 651 00:32:55,880 --> 00:32:57,960 Speaker 1: it would get stripped away by the Sun or it 652 00:32:57,960 --> 00:33:00,600 Speaker 1: would just drift away because remember remember that the Moon 653 00:33:00,720 --> 00:33:03,440 Speaker 1: is really pretty tiny. I mean, it looks impressive in 654 00:33:03,480 --> 00:33:06,440 Speaker 1: the sky, but it's got like one percent of the 655 00:33:06,480 --> 00:33:09,360 Speaker 1: mass of the Earth, and its surface gravity is very, 656 00:33:09,440 --> 00:33:11,600 Speaker 1: very low, and so the escape velossity of the Moon 657 00:33:11,720 --> 00:33:13,560 Speaker 1: is just much lower than it is here on Earth, 658 00:33:13,600 --> 00:33:16,440 Speaker 1: which makes it easier for the stuff to boil away. 659 00:33:16,640 --> 00:33:18,479 Speaker 1: So I feel like I would have, you know, as 660 00:33:18,520 --> 00:33:21,120 Speaker 1: someone who thinks about terror forming a little, I would 661 00:33:21,120 --> 00:33:24,360 Speaker 1: have thought, well, maybe we can, at great, great, great, great, great, 662 00:33:24,400 --> 00:33:27,560 Speaker 1: great great great expense, give the Moon a magnetic field 663 00:33:28,280 --> 00:33:30,880 Speaker 1: to hold onto an atmosphere. But now what you've told 664 00:33:30,920 --> 00:33:33,200 Speaker 1: me is that physics doesn't have that figured out yet, 665 00:33:33,280 --> 00:33:35,560 Speaker 1: and a magnetic field may or may not help, So 666 00:33:35,600 --> 00:33:37,560 Speaker 1: there's maybe nothing we can do about the Moon not 667 00:33:37,640 --> 00:33:40,200 Speaker 1: having an atmosphere. Giving the Moon an atmosphere is definitely 668 00:33:40,240 --> 00:33:42,800 Speaker 1: a hopeless engineering project. I mean, you need to build 669 00:33:42,840 --> 00:33:45,080 Speaker 1: like a containment vessel, right, You need to like put 670 00:33:45,120 --> 00:33:48,280 Speaker 1: the whole Moon inside a glass bulb or something crazy. 671 00:33:48,360 --> 00:33:51,360 Speaker 1: Because it's not just that it doesn't have the gravity 672 00:33:51,400 --> 00:33:54,040 Speaker 1: to hold onto that gas envelope on its own. It's 673 00:33:54,040 --> 00:33:56,320 Speaker 1: a pretty harsh environment. I mean, the surface of the 674 00:33:56,320 --> 00:33:58,920 Speaker 1: Moon gets to like two hundred and fifty fahrenheit a 675 00:33:59,000 --> 00:34:01,760 Speaker 1: hundred and twenty cell see us during the day, which 676 00:34:01,800 --> 00:34:04,760 Speaker 1: makes it pretty easy to boil this stuff off, because remember, 677 00:34:04,800 --> 00:34:07,240 Speaker 1: it's a trade off between the temperature of the gas, 678 00:34:07,280 --> 00:34:10,680 Speaker 1: which means fast moving particles, and the gravity of the object. 679 00:34:10,719 --> 00:34:13,120 Speaker 1: If you have a small object, it's only hope for 680 00:34:13,239 --> 00:34:16,480 Speaker 1: holding onto its gas is if that gas is very cold, 681 00:34:16,600 --> 00:34:19,520 Speaker 1: meaning it's slow moving. But if the gas is hot 682 00:34:19,560 --> 00:34:22,200 Speaker 1: and the object is small, then that stuff is just 683 00:34:22,200 --> 00:34:24,400 Speaker 1: going to boil off into space. All right. I'm not 684 00:34:24,440 --> 00:34:26,919 Speaker 1: investing in that project. And people have been wondering about 685 00:34:26,960 --> 00:34:29,040 Speaker 1: the Moon's atmosphere for a long time. It's not for 686 00:34:29,040 --> 00:34:31,840 Speaker 1: a very long time that we've understood the source of 687 00:34:31,840 --> 00:34:34,279 Speaker 1: the Earth's atmosphere. This is a very complex story. It 688 00:34:34,320 --> 00:34:36,120 Speaker 1: took us a long time to piece together, and so 689 00:34:36,160 --> 00:34:38,560 Speaker 1: it wasn't until like the seventeen hundreds of people were 690 00:34:38,560 --> 00:34:41,600 Speaker 1: speculating about whether the Moon had an atmosphere, and people considered, 691 00:34:41,800 --> 00:34:44,480 Speaker 1: oh my gosh, maybe the Moon doesn't have any air 692 00:34:44,560 --> 00:34:46,520 Speaker 1: on it. They just for a long time assumed that 693 00:34:46,560 --> 00:34:48,880 Speaker 1: it would because the Earth did right, But it's not 694 00:34:48,920 --> 00:34:51,440 Speaker 1: actually that hard to tell even from the Earth that 695 00:34:51,480 --> 00:34:54,200 Speaker 1: the Moon must not have any atmosphere, and it's using 696 00:34:54,239 --> 00:34:56,440 Speaker 1: the same technique we talked about earlier. Remember, if we 697 00:34:56,480 --> 00:34:59,000 Speaker 1: are studying exoplanet, one thing we can do is look 698 00:34:59,040 --> 00:35:02,239 Speaker 1: at the light that passes through the atmosphere of those 699 00:35:02,239 --> 00:35:05,160 Speaker 1: exoplanets to see that there is an atmosphere and what's 700 00:35:05,200 --> 00:35:06,839 Speaker 1: in it. But you can do the same thing when 701 00:35:06,920 --> 00:35:09,040 Speaker 1: you look at the Moon. You can look at sunlight 702 00:35:09,080 --> 00:35:11,520 Speaker 1: that passes very very close to the Moon and see 703 00:35:11,880 --> 00:35:15,080 Speaker 1: is it absorbed, is it getting reflected, is it getting scattered. 704 00:35:15,239 --> 00:35:17,920 Speaker 1: You can basically use the sun as a probe of 705 00:35:18,000 --> 00:35:20,920 Speaker 1: what's right around the Moon. But we've been there, so 706 00:35:20,960 --> 00:35:23,680 Speaker 1: we don't have to rely on far off things. Didn't 707 00:35:23,680 --> 00:35:25,839 Speaker 1: they try to measure an atmosphere when they got there, 708 00:35:26,080 --> 00:35:28,000 Speaker 1: You're right, we have been there, and the Apollo missians 709 00:35:28,040 --> 00:35:31,480 Speaker 1: have a long series of experiments trying to measure things 710 00:35:31,520 --> 00:35:34,800 Speaker 1: on the Moon, looking for trace atmosphere and really finding 711 00:35:34,840 --> 00:35:38,719 Speaker 1: almost nothing. A Poulost seventeen saw a little bit of 712 00:35:38,760 --> 00:35:42,799 Speaker 1: evidence for UV emitting gases, but there's another big clue 713 00:35:42,840 --> 00:35:44,960 Speaker 1: about the Moon's atmosphere from the fact that we did 714 00:35:45,040 --> 00:35:47,920 Speaker 1: go there. You know, those footprints that people left on 715 00:35:47,960 --> 00:35:51,479 Speaker 1: the moon, they're still there. You like, write your name 716 00:35:51,520 --> 00:35:54,160 Speaker 1: in the sand on the Moon, and you could look 717 00:35:54,200 --> 00:35:56,239 Speaker 1: at it twenty years later from the surface of the 718 00:35:56,239 --> 00:35:59,239 Speaker 1: Earth and read your own handwriting, because there's basically no 719 00:35:59,480 --> 00:36:01,879 Speaker 1: whether on the moon, right, there's no wind of their 720 00:36:01,960 --> 00:36:04,720 Speaker 1: like blow things around, and so it's sort of amazing 721 00:36:04,760 --> 00:36:07,360 Speaker 1: that the rover tracks and the footprints they're all still 722 00:36:07,480 --> 00:36:09,800 Speaker 1: up there. You know, I've read that pizza hut was 723 00:36:09,840 --> 00:36:13,640 Speaker 1: looking into the cost estimate for like lasering its name 724 00:36:13,719 --> 00:36:19,279 Speaker 1: onto the moon. Yeah, it sounds like it would have 725 00:36:19,320 --> 00:36:21,759 Speaker 1: been a good long term investment because once it's up there, 726 00:36:21,880 --> 00:36:24,000 Speaker 1: it's not going away, right, But I think they did 727 00:36:24,080 --> 00:36:29,160 Speaker 1: determine it was probably not cost effective and actually might 728 00:36:29,239 --> 00:36:33,120 Speaker 1: make people angry, And in a million years archaeologists are 729 00:36:33,120 --> 00:36:35,719 Speaker 1: gonna be like, what is a pizza and why did 730 00:36:35,800 --> 00:36:39,400 Speaker 1: humans think to write about it on the moon? Right? 731 00:36:39,440 --> 00:36:41,640 Speaker 1: And why are they keeping it in a hut? Yeah? 732 00:36:43,000 --> 00:36:45,880 Speaker 1: Bad idea, bad idea. So it seems like when you 733 00:36:45,920 --> 00:36:49,120 Speaker 1: and I talk about something, the answer is never yes 734 00:36:49,719 --> 00:36:53,040 Speaker 1: or no. The answer is always something like yes but 735 00:36:54,600 --> 00:36:57,960 Speaker 1: or yes, well, so is is there a will? Is 736 00:36:58,000 --> 00:37:01,440 Speaker 1: there something sort of like an atmosphere? Sometimes where's the 737 00:37:01,480 --> 00:37:05,520 Speaker 1: well actually parked to this this episode? Yeah, there's definitely 738 00:37:05,520 --> 00:37:08,319 Speaker 1: a well actually varked to this episode, otherwise it would 739 00:37:08,320 --> 00:37:10,160 Speaker 1: have been very short. And the answer is that the 740 00:37:10,200 --> 00:37:13,840 Speaker 1: Moon technically doesn't have an atmosphere, but it does have 741 00:37:14,040 --> 00:37:17,360 Speaker 1: an exosphere. Remember earlier we were talking about the Earth 742 00:37:17,400 --> 00:37:20,680 Speaker 1: having an exosphere. Up above the atmosphere, there's this point 743 00:37:20,719 --> 00:37:23,200 Speaker 1: where there are gases, but they're very diffuse and very 744 00:37:23,239 --> 00:37:25,560 Speaker 1: low density, so they're not bumping into each other. The 745 00:37:25,600 --> 00:37:28,960 Speaker 1: Moon does have some gas particles and some other stuff 746 00:37:29,000 --> 00:37:32,160 Speaker 1: floating around near it in this envelope that don't bump 747 00:37:32,200 --> 00:37:34,359 Speaker 1: into each other. And so we can say the Moon 748 00:37:34,440 --> 00:37:36,920 Speaker 1: has an exosphere, and you might wonder, like, well, how 749 00:37:37,000 --> 00:37:39,480 Speaker 1: is it possible for it to hold onto its exosphere 750 00:37:39,520 --> 00:37:42,080 Speaker 1: if it can't hold onto an atmosphere, and it's part 751 00:37:42,080 --> 00:37:45,719 Speaker 1: of this fascinating dynamic story. Basically, it can't hold onto it, 752 00:37:45,760 --> 00:37:48,520 Speaker 1: but it has sources of new material at the same 753 00:37:48,600 --> 00:37:51,319 Speaker 1: time as it has sinks ways to get rid of it, 754 00:37:51,719 --> 00:37:55,839 Speaker 1: so it's constantly losing its exosphere and getting it replenished 755 00:37:56,239 --> 00:37:57,839 Speaker 1: tell me more about where it comes from. So it's 756 00:37:57,840 --> 00:38:02,480 Speaker 1: really a fun story. The Moon's exosphere actually comes from itself, right, 757 00:38:02,520 --> 00:38:05,040 Speaker 1: So things are constantly hitting the Moon, like you have 758 00:38:05,160 --> 00:38:08,279 Speaker 1: meteorites and then includes like really tiny little rocks that 759 00:38:08,280 --> 00:38:10,440 Speaker 1: are hitting the surface of the Moon. And we know 760 00:38:10,560 --> 00:38:12,080 Speaker 1: this is happening because you look up at the Moon 761 00:38:12,120 --> 00:38:14,680 Speaker 1: and it's covered with craters, right, which means that things 762 00:38:14,680 --> 00:38:17,000 Speaker 1: are constantly impacting it. Well, what happens if you don't 763 00:38:17,000 --> 00:38:19,320 Speaker 1: have very strong gravity and you get impacted with the 764 00:38:19,360 --> 00:38:21,879 Speaker 1: meteorite is that it sprays a bunch of stuff up 765 00:38:21,920 --> 00:38:25,600 Speaker 1: above the surface, and that stuff doesn't all immediately float 766 00:38:25,600 --> 00:38:27,799 Speaker 1: back down. Some of it's pretty light, and it's sort 767 00:38:27,800 --> 00:38:30,200 Speaker 1: of like hangs out there a little bit, like this 768 00:38:30,600 --> 00:38:34,000 Speaker 1: cloud of dust particles. So when when you say a 769 00:38:34,000 --> 00:38:39,040 Speaker 1: little bit, do you mean like decades or like that's 770 00:38:39,040 --> 00:38:41,480 Speaker 1: a great question. I think that for an individual particle, 771 00:38:41,520 --> 00:38:43,400 Speaker 1: it can vary a lot. Some of them might just 772 00:38:43,440 --> 00:38:45,640 Speaker 1: stay in the moon for minutes, some of them might 773 00:38:45,640 --> 00:38:49,520 Speaker 1: float around for days or years or decades. I don't 774 00:38:49,520 --> 00:38:51,080 Speaker 1: think that any of those things are going to last 775 00:38:51,120 --> 00:38:53,560 Speaker 1: for more than decades though, Okay, so it must be 776 00:38:53,560 --> 00:38:56,600 Speaker 1: getting pounded pretty often then, or does it have an 777 00:38:56,600 --> 00:38:59,840 Speaker 1: exosphere sometimes but not all the time. It has a 778 00:39:00,000 --> 00:39:02,880 Speaker 1: constant exosphere. But I have to emphasize that this is 779 00:39:03,080 --> 00:39:06,480 Speaker 1: very very low density. We're talking about like a few 780 00:39:06,560 --> 00:39:10,400 Speaker 1: hundred atoms per cubic centimeter. The Earth's atmosphere is like 781 00:39:10,480 --> 00:39:14,799 Speaker 1: ten to the nineteen particles per cubic centimeter, so we're 782 00:39:14,800 --> 00:39:18,440 Speaker 1: talking about something very very very very thin. You know, 783 00:39:18,560 --> 00:39:21,760 Speaker 1: the I S S the International Space Station, it flies 784 00:39:21,840 --> 00:39:25,200 Speaker 1: through the Earth's exosphere, which is about as dense. So 785 00:39:25,239 --> 00:39:27,960 Speaker 1: we're talking about the Moon having an exosphere which is 786 00:39:28,000 --> 00:39:30,120 Speaker 1: similar to like what you would feel if you stuck 787 00:39:30,160 --> 00:39:32,239 Speaker 1: your head out of the window and on the I. 788 00:39:32,520 --> 00:39:37,400 Speaker 1: S S, which I do not recommend remend you. So 789 00:39:37,440 --> 00:39:39,560 Speaker 1: if you have like a dog on the Moon in 790 00:39:39,600 --> 00:39:42,360 Speaker 1: your rover, and maybe you've called your dog rover, don't 791 00:39:42,440 --> 00:39:45,040 Speaker 1: encourage it to stick its head out because there's not 792 00:39:45,080 --> 00:39:47,719 Speaker 1: really a lot there. But it is really fascinating sort 793 00:39:47,760 --> 00:39:51,080 Speaker 1: of physics because it's not just like common fragments and meteorites. 794 00:39:51,320 --> 00:39:53,919 Speaker 1: It's other processes as well. We talked about the sun 795 00:39:54,320 --> 00:39:57,240 Speaker 1: blasting is free of an atmosphere, Well, that solar wind 796 00:39:57,320 --> 00:40:01,560 Speaker 1: also helps generate new atmosphere because each of those particles 797 00:40:01,640 --> 00:40:05,080 Speaker 1: hitting the surface of the Moon kicks up stuff from 798 00:40:05,120 --> 00:40:08,520 Speaker 1: the Moon's surface, right like knock stuff off the surface, 799 00:40:08,600 --> 00:40:10,920 Speaker 1: which then becomes part of the exosphere. Some of that 800 00:40:10,960 --> 00:40:13,640 Speaker 1: again settles back down, but some of it doesn't. Some 801 00:40:13,719 --> 00:40:16,320 Speaker 1: of it floats around for a while before then getting 802 00:40:16,320 --> 00:40:19,240 Speaker 1: like ionized by the Sun and then floating off into space. 803 00:40:19,560 --> 00:40:24,000 Speaker 1: Does it get like pushed in a certain direction by 804 00:40:24,120 --> 00:40:26,960 Speaker 1: the wind or is it just sort of like floating 805 00:40:26,960 --> 00:40:30,160 Speaker 1: off in all directions. So there's an envelope surrounding the 806 00:40:30,200 --> 00:40:32,400 Speaker 1: Moon of all of this stuff, and it's constantly getting 807 00:40:32,440 --> 00:40:35,000 Speaker 1: blown away. You know how commets have a tail, right, 808 00:40:35,040 --> 00:40:37,640 Speaker 1: They have a tail because the solar wind is pushing 809 00:40:37,640 --> 00:40:39,799 Speaker 1: them away. You imagine a comet has a tail because 810 00:40:39,840 --> 00:40:41,799 Speaker 1: it's like streaking through the sky and it's sort of 811 00:40:41,800 --> 00:40:43,680 Speaker 1: like comic book wiggles or motion behind it. With the 812 00:40:43,719 --> 00:40:46,800 Speaker 1: largest contribution for a comet's tail is actually the solar wind, 813 00:40:46,960 --> 00:40:49,000 Speaker 1: and so the tail points away from the Sun, not 814 00:40:49,120 --> 00:40:52,080 Speaker 1: always away from the direction of its motion. And the 815 00:40:52,160 --> 00:40:54,400 Speaker 1: same thing is true of the Moon. It has this 816 00:40:54,520 --> 00:40:58,200 Speaker 1: sort of short lived envelope that's constantly being refreshed, and 817 00:40:58,239 --> 00:41:00,920 Speaker 1: it also has a tail. We can now see it 818 00:41:01,040 --> 00:41:03,680 Speaker 1: from Earth using special telescopes that we have to like 819 00:41:03,920 --> 00:41:06,480 Speaker 1: block the light from the actual part of the Moon's surface, 820 00:41:06,520 --> 00:41:08,640 Speaker 1: so we can see just around it, like the corona 821 00:41:08,680 --> 00:41:11,400 Speaker 1: of the Moon. And they can see this envelope of 822 00:41:11,480 --> 00:41:14,279 Speaker 1: sodium around the Moon, and it has this tail that's 823 00:41:14,280 --> 00:41:17,439 Speaker 1: getting blown by the Sun away from the Moon. That's 824 00:41:17,480 --> 00:41:19,480 Speaker 1: so cool. I wish I could see that in real life. 825 00:41:20,360 --> 00:41:22,240 Speaker 1: If you google for it, there are these really cool 826 00:41:22,320 --> 00:41:24,520 Speaker 1: videos where you can see the Moon going around the 827 00:41:24,560 --> 00:41:27,040 Speaker 1: Earth and when the Moon is between the Earth and 828 00:41:27,080 --> 00:41:30,120 Speaker 1: the Sun, the Earth is in the Moon's tail. Right, 829 00:41:30,120 --> 00:41:35,600 Speaker 1: we're like eating the Moon's sodium dust is do we 830 00:41:35,640 --> 00:41:37,719 Speaker 1: retain any of it or does it just pass through? 831 00:41:38,040 --> 00:41:39,760 Speaker 1: We can retain it, you know, it just gets gathered 832 00:41:39,760 --> 00:41:42,320 Speaker 1: by the Earth. But again these are very very small amounts. 833 00:41:42,400 --> 00:41:44,120 Speaker 1: Is the reason it took us a long time to 834 00:41:44,280 --> 00:41:47,240 Speaker 1: even spot it. It was like that we first saw 835 00:41:47,280 --> 00:41:50,719 Speaker 1: the Moon's like sodium envelope and this tail. It takes 836 00:41:50,760 --> 00:41:53,640 Speaker 1: a long time. And one reason that they actually spotted 837 00:41:53,680 --> 00:41:56,480 Speaker 1: it is really cool is because of the landed meteor shower. 838 00:41:56,600 --> 00:41:58,640 Speaker 1: You know, when there's a meteor shower. It means like 839 00:41:58,680 --> 00:42:02,600 Speaker 1: spectacular things happening in our atmosphere. It also means more 840 00:42:02,760 --> 00:42:06,080 Speaker 1: things hitting the Moon's surface, which kicks up more stuff, 841 00:42:06,239 --> 00:42:09,919 Speaker 1: which enhances the Moon's exosphere and its tail. So during 842 00:42:09,960 --> 00:42:15,200 Speaker 1: the Leanded meteor shower, the Moon's exosphere was tripled in density, 843 00:42:15,440 --> 00:42:18,880 Speaker 1: heavy stuff, heavy stuff exactly. So there's a lot of 844 00:42:18,880 --> 00:42:21,600 Speaker 1: these processes going on, you know, like not just the 845 00:42:21,600 --> 00:42:25,799 Speaker 1: solar wind and commentary impact, also just photons. This is 846 00:42:25,840 --> 00:42:29,560 Speaker 1: fun process called desorption. You know, we're used to the 847 00:42:29,560 --> 00:42:32,680 Speaker 1: process of absorption where you can like gobble something up, 848 00:42:33,040 --> 00:42:35,920 Speaker 1: but desorption is when a photon hits something and it 849 00:42:36,040 --> 00:42:38,080 Speaker 1: kicks something off, just like when a meteor hits the 850 00:42:38,120 --> 00:42:40,000 Speaker 1: surface and kicks off a rock. Now we're talking about 851 00:42:40,000 --> 00:42:42,160 Speaker 1: a photon hitting an atom and giving it the energy 852 00:42:42,200 --> 00:42:44,719 Speaker 1: to like escape whatever bonds it was in and it 853 00:42:44,800 --> 00:42:47,399 Speaker 1: comes off the surface. And so the Moon has all 854 00:42:47,440 --> 00:42:51,640 Speaker 1: these various ways to replenish its exosphere and all these 855 00:42:51,640 --> 00:42:54,680 Speaker 1: ways to lose it. So it's like more like a flow, right, 856 00:42:54,680 --> 00:42:57,080 Speaker 1: It's not just like a gaseous pool. It's like the 857 00:42:57,160 --> 00:43:00,040 Speaker 1: stuff flowing off the Moon and getting a braid and 858 00:43:00,280 --> 00:43:02,840 Speaker 1: by everything that's around it. Does this mean that that 859 00:43:02,960 --> 00:43:07,240 Speaker 1: the other moons in the Solar System might also have tails? 860 00:43:07,280 --> 00:43:10,239 Speaker 1: Almost certainly every object in the Solar System has an 861 00:43:10,280 --> 00:43:13,279 Speaker 1: exo sphere because they're not just alone, right, They're all 862 00:43:13,360 --> 00:43:16,359 Speaker 1: in the Solar wind. They're all getting constantly bombarded by 863 00:43:16,400 --> 00:43:19,720 Speaker 1: little meteor fragments or big objects. So the Solar System 864 00:43:19,760 --> 00:43:22,080 Speaker 1: is a very dynamic place. And because of it, all 865 00:43:22,120 --> 00:43:25,960 Speaker 1: these things are constantly providing sources for their own exosphere 866 00:43:26,000 --> 00:43:28,560 Speaker 1: and then also losing them constantly. So we think that 867 00:43:28,600 --> 00:43:32,239 Speaker 1: for example, and slate Us in Europa, and Callisto and 868 00:43:32,320 --> 00:43:36,440 Speaker 1: Ganymede and even dwarf planets like Ceres in the Asteroid 869 00:43:36,480 --> 00:43:41,000 Speaker 1: Belt probably have their own little exosphere. Not quite an atmosphere, right, 870 00:43:41,280 --> 00:43:44,200 Speaker 1: but a little exosphere of their own. Interesting. And then, 871 00:43:44,200 --> 00:43:46,279 Speaker 1: and you know, as somebod who thinks about settlements, these 872 00:43:46,280 --> 00:43:49,200 Speaker 1: exo spheres will probably never be useful for anything, because 873 00:43:49,200 --> 00:43:51,000 Speaker 1: even if they were made out of useful stuff, it's 874 00:43:51,080 --> 00:43:53,640 Speaker 1: so it would be so hard to extract it. Yeah, 875 00:43:53,640 --> 00:43:56,480 Speaker 1: exactly right. There's probably no economic benefit there, But there 876 00:43:56,560 --> 00:43:59,120 Speaker 1: is a lot of physics that you can learn because 877 00:43:59,160 --> 00:44:02,480 Speaker 1: their collision list they're not interacting with each other, mostly 878 00:44:02,480 --> 00:44:04,920 Speaker 1: just flying along and doing their own dance. Each one 879 00:44:04,960 --> 00:44:07,759 Speaker 1: tells you something different about a physics process that's going on. 880 00:44:08,080 --> 00:44:10,080 Speaker 1: It helps to sort of like isolate the things and 881 00:44:10,120 --> 00:44:12,640 Speaker 1: study them in detail. So we think that each of 882 00:44:12,640 --> 00:44:17,279 Speaker 1: these Solar System bodies probably have different sinks and different sources. Right. 883 00:44:17,400 --> 00:44:20,080 Speaker 1: Some of them, for example, are really cold on the surface, 884 00:44:20,080 --> 00:44:21,960 Speaker 1: and that can be a sink. It can be like 885 00:44:22,000 --> 00:44:24,320 Speaker 1: that there's so it's so cold that it's like sticking 886 00:44:24,320 --> 00:44:27,360 Speaker 1: your tongue to a flagpole, that when those little molecules 887 00:44:27,400 --> 00:44:30,000 Speaker 1: touch the surface they stick on. So the exospheres are 888 00:44:30,040 --> 00:44:31,920 Speaker 1: a really cool way to learn a lot about the 889 00:44:31,960 --> 00:44:34,839 Speaker 1: surface of these planets without even landing on them. Right, 890 00:44:34,840 --> 00:44:37,280 Speaker 1: You can pass your satellite near one of these objects 891 00:44:37,320 --> 00:44:39,680 Speaker 1: and sample them and learn a lot about what's going 892 00:44:39,719 --> 00:44:42,800 Speaker 1: on in the surface without actually having to land. It's incredible. 893 00:44:42,880 --> 00:44:46,560 Speaker 1: We can collect enough data from these very thin exospheres 894 00:44:46,600 --> 00:44:48,319 Speaker 1: to learn this kind of stuff. Yeah, which you need 895 00:44:48,440 --> 00:44:50,879 Speaker 1: is a mass spectrometer. One of these devices that tells 896 00:44:50,920 --> 00:44:53,960 Speaker 1: you like, oh, you have seventy two atoms of hydrogen 897 00:44:54,120 --> 00:44:56,960 Speaker 1: or sixteen atoms of sodium. Can tell you exactly what 898 00:44:57,040 --> 00:44:59,440 Speaker 1: the composition is, and that gives you a lot of 899 00:44:59,440 --> 00:45:02,080 Speaker 1: clues to how these things formed and also what's going 900 00:45:02,160 --> 00:45:04,560 Speaker 1: on on their surface right now. I spoke to one 901 00:45:04,600 --> 00:45:06,600 Speaker 1: of my old friends from grad school who's now an 902 00:45:06,600 --> 00:45:09,920 Speaker 1: expert in this. He's a he's a space geoscientist, and 903 00:45:09,920 --> 00:45:13,239 Speaker 1: he said, any rocky object in space gets bombarded by 904 00:45:13,280 --> 00:45:16,040 Speaker 1: all sorts of crap that can liberate materials from the 905 00:45:16,080 --> 00:45:20,759 Speaker 1: surface and form an exo sphere is crap a technical term. 906 00:45:20,800 --> 00:45:23,080 Speaker 1: I mean he's speaking as a scientist, he's a professor, 907 00:45:23,160 --> 00:45:26,319 Speaker 1: So now it is a technical term. Fantastic. I didn't 908 00:45:26,320 --> 00:45:28,600 Speaker 1: realize it was that easy, And I guess that means that, 909 00:45:28,640 --> 00:45:31,120 Speaker 1: you know, even objects like the I s s, which 910 00:45:31,160 --> 00:45:33,359 Speaker 1: are getting hit by the solar wind and getting hit 911 00:45:33,360 --> 00:45:36,480 Speaker 1: by all sorts of stuff, are also like liberating little bits, right, 912 00:45:36,600 --> 00:45:40,239 Speaker 1: Spellation and abration are giving off little particles. And so 913 00:45:40,600 --> 00:45:45,160 Speaker 1: even like an individual astronaut out there in space on 914 00:45:45,200 --> 00:45:50,040 Speaker 1: an e v A must have their own little exo sphere. Somehow, 915 00:45:50,080 --> 00:45:51,839 Speaker 1: I feel like that would make me feel even more 916 00:45:51,880 --> 00:45:55,360 Speaker 1: important to know I had my own little exo sphere exactly, 917 00:45:55,400 --> 00:45:58,359 Speaker 1: and you don't even have to burp it out. That's right. 918 00:45:58,400 --> 00:46:01,359 Speaker 1: It's one thing we have advantage we have over Earth, 919 00:46:01,640 --> 00:46:04,480 Speaker 1: and so recent studies of the Moon suggests that, of 920 00:46:04,520 --> 00:46:07,480 Speaker 1: course there's sodium there. We can see sodium pretty clearly 921 00:46:07,560 --> 00:46:10,080 Speaker 1: because it's very responsive in the UV, which is what 922 00:46:10,200 --> 00:46:12,560 Speaker 1: these telescopes are good at looking at. But there's also 923 00:46:12,640 --> 00:46:16,120 Speaker 1: helium there, there's neon, there's argon. There might even be 924 00:46:16,160 --> 00:46:20,120 Speaker 1: like carbon burying species up there in the Moon's exosphere. 925 00:46:21,280 --> 00:46:23,560 Speaker 1: But there's not a lot of carbon on the Moon. 926 00:46:24,280 --> 00:46:26,960 Speaker 1: Where's the carbon coming from. There's definitely not a lot, 927 00:46:27,000 --> 00:46:29,839 Speaker 1: but some of it could be coming from the asteroid impacts, right. 928 00:46:29,920 --> 00:46:32,360 Speaker 1: Asteroids sometimes are have silica in them, sometimes they have 929 00:46:32,400 --> 00:46:37,080 Speaker 1: carbon in them. They sometimes even have complex organic molecules. Interesting. 930 00:46:37,360 --> 00:46:39,920 Speaker 1: So when you look up at the daytime sky, you're 931 00:46:39,920 --> 00:46:43,000 Speaker 1: seeing mostly the blue from our atmosphere, but beyond that 932 00:46:43,120 --> 00:46:46,319 Speaker 1: there's also the Earth's exosphere, which is so dilute that 933 00:46:46,360 --> 00:46:50,200 Speaker 1: you cannot see it. It's black, it's invisible, but it's there. 934 00:46:50,360 --> 00:46:53,239 Speaker 1: It's doing something. And everything else out there in the 935 00:46:53,239 --> 00:46:57,040 Speaker 1: Solar system, the Moon, mercury, all the other objects which 936 00:46:57,040 --> 00:47:00,200 Speaker 1: are quote bombarded by all sorts of crap, they also 937 00:47:00,320 --> 00:47:02,960 Speaker 1: generate an exo sphere, and that tells you that the 938 00:47:03,000 --> 00:47:06,520 Speaker 1: Solar System is not a static thing. It's a dance. 939 00:47:06,719 --> 00:47:10,719 Speaker 1: Everybody is giving off gas and accepting photons and interacting 940 00:47:10,800 --> 00:47:14,040 Speaker 1: with each other. So the Solar system has an exciting future. 941 00:47:14,239 --> 00:47:16,040 Speaker 1: You know, I usually think dances are better when they 942 00:47:16,040 --> 00:47:19,840 Speaker 1: don't involve gas, but but but this one is beautiful. 943 00:47:20,200 --> 00:47:22,440 Speaker 1: This is sort of how objects in the Solar System 944 00:47:22,520 --> 00:47:25,680 Speaker 1: talk to each other and evolve. All right, Thanks very 945 00:47:25,719 --> 00:47:28,360 Speaker 1: much for joining us on this exploration of whether or 946 00:47:28,400 --> 00:47:31,120 Speaker 1: not the Moon has an atmosphere. To put a pin 947 00:47:31,200 --> 00:47:33,239 Speaker 1: in it, I would say the Moon does not have 948 00:47:33,360 --> 00:47:36,720 Speaker 1: an atmosphere, but it definitely does have an exo sphere. 949 00:47:36,800 --> 00:47:38,920 Speaker 1: And thanks very much to our exo host Kelly for 950 00:47:39,000 --> 00:47:42,239 Speaker 1: joining us today. Thanks. I had a great time. I 951 00:47:42,320 --> 00:47:45,279 Speaker 1: was gonna say I had gas e time, but that 952 00:47:45,360 --> 00:47:47,120 Speaker 1: just doesn't sound what. It's good. I hope you didn't 953 00:47:47,120 --> 00:47:50,760 Speaker 1: have gas, but I thought it was a pretty nice atmosphere. Agreed, 954 00:47:51,239 --> 00:47:53,839 Speaker 1: that was a good punt. All right, Thanks for joining us. 955 00:47:53,840 --> 00:47:56,440 Speaker 1: Everyone tune in next time. All right, that was fun. 956 00:48:04,480 --> 00:48:07,280 Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain 957 00:48:07,360 --> 00:48:10,200 Speaker 1: the Universe is a production of I Heart Radio. For 958 00:48:10,360 --> 00:48:14,040 Speaker 1: more podcast from My Heart Radio, visit the I heart radio, app, 959 00:48:14,320 --> 00:48:17,760 Speaker 1: Apple podcasts, or wherever you listen to your favorite shows. 960 00:48:19,640 --> 00:48:19,680 Speaker 1: H