1
00:00:08,520 --> 00:00:11,320
Speaker 1: Hey, Kelly, I have a controversial question for you.

2
00:00:11,760 --> 00:00:14,840
Speaker 2: Oh boy, coming from you that makes me particularly nervous.

3
00:00:15,280 --> 00:00:17,120
Speaker 2: Is this another episode I'm gonna have to make sure

4
00:00:17,160 --> 00:00:18,279
Speaker 2: my kids don't listen.

5
00:00:18,040 --> 00:00:21,520
Speaker 1: To no, but it might cause some other kind of

6
00:00:21,520 --> 00:00:22,320
Speaker 1: family drama.

7
00:00:22,560 --> 00:00:24,119
Speaker 2: Okay, now you have my attention.

8
00:00:25,120 --> 00:00:27,720
Speaker 1: Well, you know, since you're married to a cartoonist, I'm

9
00:00:27,760 --> 00:00:30,320
Speaker 1: wondering if I'm allowed to ask you whether you're a

10
00:00:30,360 --> 00:00:32,400
Speaker 1: fan of a different cartoon.

11
00:00:32,800 --> 00:00:36,040
Speaker 2: Well, that depends if it's a rival cartoon or not.

12
00:00:38,560 --> 00:00:42,080
Speaker 1: So I'm wondering if you have a favorite cartoon from

13
00:00:42,280 --> 00:00:43,080
Speaker 1: the Far Side.

14
00:00:43,440 --> 00:00:46,080
Speaker 2: Oh, I mean he hasn't updated for a while, right,

15
00:00:46,120 --> 00:00:48,440
Speaker 2: I mean, I suppose he's still competition. But anyway, all right,

16
00:00:48,479 --> 00:00:50,519
Speaker 2: let's see, let's see. Oh, so hard to pick so

17
00:00:50,560 --> 00:00:54,320
Speaker 2: many favorites. So there's one where there's a slide, you know,

18
00:00:54,440 --> 00:00:57,640
Speaker 2: like a kid's playground, and some spiders have built a

19
00:00:57,760 --> 00:01:02,840
Speaker 2: net or a web along the bottom, and one spider

20
00:01:02,920 --> 00:01:05,760
Speaker 2: is saying something like, if we can pull this off,

21
00:01:06,360 --> 00:01:10,080
Speaker 2: we'll never be hungry again, nor something like that, And I,

22
00:01:10,480 --> 00:01:13,240
Speaker 2: as an invert person, just thought that that was amazing.

23
00:01:13,240 --> 00:01:14,840
Speaker 2: And of course I liked the like School for the

24
00:01:14,880 --> 00:01:18,200
Speaker 2: Gifted the one that was on T shirts when I

25
00:01:18,280 --> 00:01:20,160
Speaker 2: was a kid. What about you, Well, I have.

26
00:01:20,040 --> 00:01:22,120
Speaker 1: To ask you. Do you see that Spider's eating a

27
00:01:22,160 --> 00:01:24,640
Speaker 1: baby cartoon differently now that you're a parent?

28
00:01:24,920 --> 00:01:26,280
Speaker 2: No, still hilarious.

29
00:01:28,040 --> 00:01:28,160
Speaker 3: Us.

30
00:01:28,200 --> 00:01:30,559
Speaker 1: I think your children should be terrified if they listen

31
00:01:30,680 --> 00:01:31,520
Speaker 1: to this episode.

32
00:01:31,959 --> 00:01:34,959
Speaker 2: Probably. Oh my gosh, poor kid won. The other day,

33
00:01:35,080 --> 00:01:37,959
Speaker 2: I told her to go get a bowl in my office,

34
00:01:38,360 --> 00:01:40,520
Speaker 2: and she thought it was going to have something like

35
00:01:40,600 --> 00:01:42,920
Speaker 2: candy in it, but she accidentally picked up the bowl

36
00:01:43,000 --> 00:01:46,440
Speaker 2: of dead insects that I found in the in the

37
00:01:46,480 --> 00:01:48,600
Speaker 2: barn that I was thinking of pinning at some point,

38
00:01:48,720 --> 00:01:51,320
Speaker 2: and they were all over my office, so she must

39
00:01:51,320 --> 00:01:53,160
Speaker 2: have seen it and thrown it up in the air

40
00:01:53,840 --> 00:01:56,320
Speaker 2: and they went all over. My kids are going to

41
00:01:56,400 --> 00:01:58,520
Speaker 2: have very high therapy bills at some point, but I

42
00:01:58,560 --> 00:01:59,440
Speaker 2: love them very much.

43
00:01:59,560 --> 00:02:01,800
Speaker 1: I think that living in your house must be even

44
00:02:01,840 --> 00:02:21,360
Speaker 1: weirder than the Far Side cartoon, almost certain. Hi. I'm Daniel.

45
00:02:21,400 --> 00:02:24,720
Speaker 1: I'm a particle physicist and a professor at UC Irvine,

46
00:02:25,000 --> 00:02:28,640
Speaker 1: and I don't think I've yet traumatized my children with insects.

47
00:02:28,840 --> 00:02:32,000
Speaker 2: Hi. I'm Kelly Wiener Smith, and I study creepy crawley

48
00:02:32,080 --> 00:02:35,840
Speaker 2: things at race university, and I'm traumatizing kids all the time.

49
00:02:36,080 --> 00:02:38,280
Speaker 1: Education through trauma is set your strategy.

50
00:02:38,400 --> 00:02:40,400
Speaker 2: That's a good way to make people remember stuff.

51
00:02:43,600 --> 00:02:45,400
Speaker 1: Where you live out on the farm, but there's lots

52
00:02:45,400 --> 00:02:48,240
Speaker 1: of access to creepy crawley weird things, and so I

53
00:02:48,280 --> 00:02:50,920
Speaker 1: hope your kids are become ver acclimatized.

54
00:02:50,280 --> 00:02:52,960
Speaker 2: To that I'm making them because it.

55
00:02:52,960 --> 00:02:56,359
Speaker 1: Takes a brave soul to explore the nature of the universe,

56
00:02:56,480 --> 00:02:59,919
Speaker 1: or even just your backyard, depending on what's slithering out there.

57
00:03:00,080 --> 00:03:02,280
Speaker 1: So whether or not you turn your eyes down to

58
00:03:02,320 --> 00:03:04,639
Speaker 1: the ground or up to the skies, there's a whole

59
00:03:04,680 --> 00:03:07,040
Speaker 1: lot of stuff to wonder about, and so welcome to

60
00:03:07,080 --> 00:03:10,000
Speaker 1: the podcast. Daniel and Jorge explain the universe in which

61
00:03:10,040 --> 00:03:12,720
Speaker 1: we do all of that wondering. We think about everything

62
00:03:12,760 --> 00:03:15,519
Speaker 1: that's between your toes and everything that your eyes can

63
00:03:15,560 --> 00:03:18,120
Speaker 1: gather as you look up into the night sky. We

64
00:03:18,160 --> 00:03:20,200
Speaker 1: think about what's on the moon, what's on the backside

65
00:03:20,240 --> 00:03:22,720
Speaker 1: of the moon, and what's in the deepest, darkest depths

66
00:03:22,760 --> 00:03:25,080
Speaker 1: of the universe. We chew all of it up and

67
00:03:25,120 --> 00:03:27,120
Speaker 1: try to digest it and explain.

68
00:03:26,800 --> 00:03:29,080
Speaker 2: It to you, and it's not always pretty.

69
00:03:31,240 --> 00:03:34,600
Speaker 1: Sometimes the truth is just gross. My typical co host

70
00:03:34,639 --> 00:03:36,680
Speaker 1: and friend, Jorge Champ can't be here today, so I'm

71
00:03:36,760 --> 00:03:39,360
Speaker 1: very glad to have one of our regular guest hosts, Kelly. Kelly,

72
00:03:39,360 --> 00:03:42,440
Speaker 1: thanks very much for joining us again and terrifying your children.

73
00:03:42,760 --> 00:03:45,320
Speaker 2: Yeah, well, I hope I could terrify some people today too.

74
00:03:45,400 --> 00:03:46,520
Speaker 2: Thanks for having me back.

75
00:03:47,560 --> 00:03:50,080
Speaker 1: But today we're not talking about the weird, creepy crawley

76
00:03:50,120 --> 00:03:54,320
Speaker 1: bits that are inside Kelly's pantry, strange as that might be.

77
00:03:55,680 --> 00:03:58,720
Speaker 1: We are turning our eyes to the sky tonight. We

78
00:03:58,760 --> 00:04:01,600
Speaker 1: are thinking about what's out there in the universe, and

79
00:04:01,640 --> 00:04:04,600
Speaker 1: what we can see and what we can't see, and

80
00:04:04,600 --> 00:04:07,520
Speaker 1: how the gravitational forces that have built the structure of

81
00:04:07,560 --> 00:04:10,720
Speaker 1: our universe also limit what we can see out there.

82
00:04:11,040 --> 00:04:12,560
Speaker 1: If you were a kid like me, then you spent

83
00:04:12,640 --> 00:04:14,280
Speaker 1: a lot of time looking up at the night sky,

84
00:04:14,480 --> 00:04:17,680
Speaker 1: not just absorbing the stars, but also gazing on the

85
00:04:17,839 --> 00:04:21,039
Speaker 1: closest object that's out there, the biggest, fattest thing in

86
00:04:21,080 --> 00:04:24,040
Speaker 1: the night sky, and that's, of course our moon. It

87
00:04:24,040 --> 00:04:26,720
Speaker 1: has so many fascinating features to it, but one of

88
00:04:26,760 --> 00:04:29,640
Speaker 1: the most interesting features is that you always see the

89
00:04:29,720 --> 00:04:33,400
Speaker 1: same features. Cally, do you remember understanding this as a kid,

90
00:04:33,520 --> 00:04:36,320
Speaker 1: or wondering about why you're always seeing the same bits

91
00:04:36,360 --> 00:04:36,880
Speaker 1: on the moon.

92
00:04:37,320 --> 00:04:40,040
Speaker 2: You know, I really wish you hadn't asked me that,

93
00:04:40,120 --> 00:04:43,479
Speaker 2: because the answer is, when I was a kid, I

94
00:04:43,560 --> 00:04:46,440
Speaker 2: didn't realize I was always seeing the same side of

95
00:04:46,440 --> 00:04:49,440
Speaker 2: the moon. That hadn't really hit me until I think, baby,

96
00:04:49,640 --> 00:04:51,640
Speaker 2: I was in college, and then I was like, wait

97
00:04:51,680 --> 00:04:53,960
Speaker 2: a minute, and I guess it just wasn't I was

98
00:04:53,960 --> 00:04:57,760
Speaker 2: looking down at the salamanders and not up at the sky.

99
00:04:58,080 --> 00:05:00,320
Speaker 2: But so, no, that is not a question I had

100
00:05:00,320 --> 00:05:03,039
Speaker 2: when I was a kid, but it should be. When

101
00:05:03,040 --> 00:05:03,760
Speaker 2: did you learn this?

102
00:05:04,080 --> 00:05:05,960
Speaker 1: I remember learning about it, I think when I was

103
00:05:06,000 --> 00:05:08,239
Speaker 1: seven or eight, But you know, my dad was pretty

104
00:05:08,240 --> 00:05:11,080
Speaker 1: into astronomy and into science, and so we talked about

105
00:05:11,080 --> 00:05:13,960
Speaker 1: this kind of stuff. Something I'm still curious about, though,

106
00:05:14,200 --> 00:05:17,440
Speaker 1: is when humanity understood that, or when humanity understood it

107
00:05:17,480 --> 00:05:22,080
Speaker 1: was an interesting question, like did ancient Chinese astronomers, who

108
00:05:22,160 --> 00:05:24,120
Speaker 1: spend a lot of time looking up at the moon

109
00:05:24,160 --> 00:05:27,520
Speaker 1: and predicting its eclipses, did they figure out that the

110
00:05:27,520 --> 00:05:29,600
Speaker 1: moon was a sphere and that it was rotating and

111
00:05:29,600 --> 00:05:31,920
Speaker 1: that it was weird that we always saw the same

112
00:05:32,000 --> 00:05:34,920
Speaker 1: side of it? Or is this just something they overlooked.

113
00:05:34,960 --> 00:05:36,359
Speaker 2: Do you know the answer to that question.

114
00:05:36,640 --> 00:05:38,520
Speaker 1: I don't know the answer to that question. I've been

115
00:05:38,560 --> 00:05:41,760
Speaker 1: digging through the history of astronomy a little bit, and

116
00:05:41,839 --> 00:05:44,640
Speaker 1: I know that Newton understood it because of his ideas

117
00:05:44,680 --> 00:05:48,000
Speaker 1: of gravitation, But digging deeper into history, it's not really

118
00:05:48,000 --> 00:05:51,360
Speaker 1: discussed very much. And I sort of wonder if people

119
00:05:51,400 --> 00:05:54,800
Speaker 1: suspected that it was just a coincidence that the Moon

120
00:05:54,920 --> 00:05:57,360
Speaker 1: rotates at this perfect rate just so that we can

121
00:05:57,400 --> 00:05:59,360
Speaker 1: only see one side of it, because you know, there

122
00:05:59,400 --> 00:06:03,760
Speaker 1: are other fascinating coincidences about the moon. For example, the

123
00:06:03,760 --> 00:06:06,440
Speaker 1: moon and the Sun happen to be the same size

124
00:06:06,480 --> 00:06:09,560
Speaker 1: in our sky, right, the Sun is much much bigger,

125
00:06:09,680 --> 00:06:12,920
Speaker 1: but much much further away, and those two numbers line

126
00:06:13,000 --> 00:06:15,640
Speaker 1: up perfectly. So the Sun and the Moon appear to

127
00:06:15,680 --> 00:06:17,600
Speaker 1: be the same size, which is why we can get

128
00:06:17,640 --> 00:06:21,000
Speaker 1: so many fascinating eclipse effects. And that, of course, is

129
00:06:21,120 --> 00:06:23,599
Speaker 1: just a coincidence. There's no like deep reason for that.

130
00:06:24,000 --> 00:06:26,800
Speaker 1: It just happens to be. These two numbers just kind

131
00:06:26,800 --> 00:06:27,960
Speaker 1: of line up in our.

132
00:06:27,960 --> 00:06:33,160
Speaker 2: Universe, and humans are notoriously tripped up by coincidences.

133
00:06:32,640 --> 00:06:35,839
Speaker 1: Exactly, And so I think ancient astronomers must have wondered

134
00:06:35,880 --> 00:06:38,480
Speaker 1: about that size, and I wonder if they also wondered

135
00:06:38,640 --> 00:06:41,560
Speaker 1: about the rotation of the moon, if they understood that. Now,

136
00:06:41,600 --> 00:06:44,640
Speaker 1: I do know that ancient Chinese astronomers had a little

137
00:06:44,680 --> 00:06:47,920
Speaker 1: bit of a disadvantage compared to, for example, ancient Greek astronomers,

138
00:06:48,160 --> 00:06:51,320
Speaker 1: because they didn't have geometry. Right, we think about the

139
00:06:51,440 --> 00:06:54,719
Speaker 1: universe in terms of geometry. You imagine how clips has happened,

140
00:06:54,720 --> 00:06:56,320
Speaker 1: and you think, probably in your head, you have a

141
00:06:56,360 --> 00:06:59,960
Speaker 1: mental picture of all these things happening and to explain it.

142
00:07:00,240 --> 00:07:03,320
Speaker 1: But Chinese astronomers didn't develop geometry, so they didn't have

143
00:07:03,400 --> 00:07:06,760
Speaker 1: the same sort of geometrical thinking that we're all very

144
00:07:06,760 --> 00:07:09,680
Speaker 1: familiar with. Instead, they had like tables of numbers, and

145
00:07:09,680 --> 00:07:12,440
Speaker 1: they had arithmetic, and they could manipulate these numbers to

146
00:07:12,520 --> 00:07:14,680
Speaker 1: do their predictions. So I think they must have thought

147
00:07:14,680 --> 00:07:16,560
Speaker 1: about these things very differently than we did.

148
00:07:16,720 --> 00:07:18,640
Speaker 2: Interesting, it's nice to have our modern tools.

149
00:07:20,360 --> 00:07:22,840
Speaker 1: Thank you to those folks who invented geometry. It turns

150
00:07:22,840 --> 00:07:23,880
Speaker 1: out to be pretty.

151
00:07:23,680 --> 00:07:25,480
Speaker 2: Useful quote unquote modern.

152
00:07:25,760 --> 00:07:25,960
Speaker 3: Yeah.

153
00:07:26,040 --> 00:07:28,360
Speaker 1: Right, And so we have been looking up in the

154
00:07:28,400 --> 00:07:30,680
Speaker 1: night sky and looking at the moon and seeing the

155
00:07:30,680 --> 00:07:33,720
Speaker 1: same side of it for thousands and thousands of years,

156
00:07:34,120 --> 00:07:37,440
Speaker 1: and now, of course we understand why. And so today

157
00:07:37,440 --> 00:07:39,400
Speaker 1: on the podcast, we're going to be digging into the

158
00:07:39,440 --> 00:07:42,320
Speaker 1: physics of the far side of the Moon and many

159
00:07:42,440 --> 00:07:46,520
Speaker 1: other objects in our solar system that exhibit the same behavior.

160
00:07:46,880 --> 00:07:54,600
Speaker 1: On today's episode, well, I answer the question what is

161
00:07:54,920 --> 00:07:56,160
Speaker 1: tidal locking?

162
00:07:56,560 --> 00:07:59,040
Speaker 2: And this is another thing that connects us to the dinosaurs, right,

163
00:07:59,040 --> 00:08:01,040
Speaker 2: because they also would have seen the same side.

164
00:08:00,880 --> 00:08:05,480
Speaker 1: Of the moon. If dinosaur geometers had figured that out, boy,

165
00:08:06,000 --> 00:08:07,440
Speaker 1: they could have written a paper and got a lot

166
00:08:07,440 --> 00:08:08,160
Speaker 1: of citations.

167
00:08:08,400 --> 00:08:10,240
Speaker 2: They really could have, and then maybe they could have

168
00:08:10,280 --> 00:08:13,880
Speaker 2: started a you know, NASA and had an asteroid deflection program.

169
00:08:13,880 --> 00:08:14,960
Speaker 2: Everything could have been different.

170
00:08:15,840 --> 00:08:17,400
Speaker 1: You sound like you're kind of hoping for that, but

171
00:08:17,440 --> 00:08:19,960
Speaker 1: you know, in that scenario, we don't exist.

172
00:08:20,280 --> 00:08:21,280
Speaker 2: Oh, good point.

173
00:08:22,040 --> 00:08:24,040
Speaker 1: We're rooting for the asteroid on that one.

174
00:08:23,800 --> 00:08:24,800
Speaker 2: That's right, we sure are.

175
00:08:25,280 --> 00:08:28,120
Speaker 1: I'm sorry dinosaurs, which puts us on the anti math

176
00:08:28,280 --> 00:08:30,760
Speaker 1: Education for Dinosaurs committee as well.

177
00:08:30,920 --> 00:08:33,559
Speaker 2: It's an uncomfortable place to be, but no, it doesn't

178
00:08:33,559 --> 00:08:36,600
Speaker 2: feel very good, but I'm firmly in this position. Yeah.

179
00:08:36,640 --> 00:08:38,760
Speaker 1: So this is a topic that affects our Moon, and

180
00:08:38,880 --> 00:08:41,200
Speaker 1: affects our planet, and affects a lot of things in

181
00:08:41,240 --> 00:08:43,599
Speaker 1: the Solar system and in other Solar system. It's a

182
00:08:43,640 --> 00:08:46,440
Speaker 1: fascinating little bit of physics. So I was curious what

183
00:08:46,559 --> 00:08:50,400
Speaker 1: people knew about the topic of title locking and if

184
00:08:50,400 --> 00:08:52,480
Speaker 1: they understood the physics of it. So I went out

185
00:08:52,480 --> 00:08:55,640
Speaker 1: there into the internet to ask folks if they understood this.

186
00:08:55,800 --> 00:08:57,760
Speaker 1: Thanks very much to those of you who participate in

187
00:08:57,800 --> 00:09:00,240
Speaker 1: this segment of the podcast to let us know what

188
00:09:00,280 --> 00:09:02,880
Speaker 1: people think about the topic of the day. If you'd

189
00:09:02,880 --> 00:09:05,160
Speaker 1: like to hear your voice for a future episode, please

190
00:09:05,200 --> 00:09:08,760
Speaker 1: don't be shy. Write to me two questions at Danielandjorge

191
00:09:09,200 --> 00:09:11,240
Speaker 1: dot com. So think about it for a minute. Do

192
00:09:11,320 --> 00:09:14,600
Speaker 1: you understand the physics of title locking? Here's what some

193
00:09:14,640 --> 00:09:15,880
Speaker 1: listeners had to say.

194
00:09:16,120 --> 00:09:20,400
Speaker 4: So, I believe that title locking is when, say, a

195
00:09:20,440 --> 00:09:23,199
Speaker 4: planet has a moon that's locked in orbit at a

196
00:09:23,240 --> 00:09:26,320
Speaker 4: certain distance, so the tides are always the same. So

197
00:09:26,440 --> 00:09:29,000
Speaker 4: I guess you could say that we're in title locking

198
00:09:29,040 --> 00:09:32,520
Speaker 4: because day in and day out, our tides go the

199
00:09:32,600 --> 00:09:33,320
Speaker 4: same because.

200
00:09:33,080 --> 00:09:34,520
Speaker 1: The moon's in a fixed orbit.

201
00:09:34,880 --> 00:09:37,520
Speaker 2: Title locking is just like our moon. We see the

202
00:09:37,559 --> 00:09:40,000
Speaker 2: same face of it at all times.

203
00:09:40,080 --> 00:09:42,520
Speaker 4: It has no spin, and the dark side of the

204
00:09:42,520 --> 00:09:43,640
Speaker 4: moon is facing outward.

205
00:09:43,800 --> 00:09:47,760
Speaker 2: It is the deformation that a celestial body so first

206
00:09:47,800 --> 00:09:52,360
Speaker 2: when it's orbiting or is orbited by another massive celestial body.

207
00:09:52,600 --> 00:09:57,319
Speaker 3: Title locking is when a lower mass body is orbiting

208
00:09:57,480 --> 00:10:00,720
Speaker 3: a much higher mass body and the the same side

209
00:10:00,840 --> 00:10:03,640
Speaker 3: always faces it, so I know that we always see

210
00:10:03,679 --> 00:10:06,880
Speaker 3: the same side of the Moon means tidally locked to

211
00:10:06,920 --> 00:10:07,280
Speaker 3: the Earth.

212
00:10:07,679 --> 00:10:10,760
Speaker 2: I was impressed that none of the listeners seemed totally

213
00:10:10,760 --> 00:10:13,920
Speaker 2: stumped by this, because I feel like tidle locking is

214
00:10:13,960 --> 00:10:17,040
Speaker 2: not necessarily something that you hear, like that at least

215
00:10:17,040 --> 00:10:20,080
Speaker 2: there's a phrase I don't hear very often, and so like,

216
00:10:20,160 --> 00:10:22,959
Speaker 2: it seems like some people knew exactly what you were

217
00:10:23,000 --> 00:10:25,439
Speaker 2: asking about, and none of them were like me when

218
00:10:25,480 --> 00:10:27,880
Speaker 2: I was a kid, and we're just totally unaware that

219
00:10:27,920 --> 00:10:29,199
Speaker 2: this is a thing that was happening.

220
00:10:29,440 --> 00:10:33,040
Speaker 1: Yeah, we got some pretty well educated listeners. The word title,

221
00:10:33,200 --> 00:10:36,080
Speaker 1: I think makes some people think of tides, which is

222
00:10:36,120 --> 00:10:39,560
Speaker 1: connected of course to tidal forces, you know, like the

223
00:10:39,600 --> 00:10:43,040
Speaker 1: Moon pulls on the Earth and squishes its oceans and

224
00:10:43,360 --> 00:10:45,880
Speaker 1: makes us have higher tides in some places and lower

225
00:10:45,880 --> 00:10:48,160
Speaker 1: tides and other places. But that's not what we mean

226
00:10:48,200 --> 00:10:51,400
Speaker 1: by title locking. Tidle locking is actually a different phenomena

227
00:10:51,640 --> 00:10:54,440
Speaker 1: we're going to dig into today. But thank you very

228
00:10:54,520 --> 00:10:57,600
Speaker 1: much to all of our volunteers. We really cherish your thoughts.

229
00:10:57,800 --> 00:11:00,360
Speaker 2: Yeah, you have a smarter than average audience, I think,

230
00:11:00,440 --> 00:11:05,880
Speaker 2: or smarter than Kelly average. I'm always impressed by the answers.

231
00:11:06,280 --> 00:11:08,199
Speaker 1: They're smart and they're good looking too.

232
00:11:08,240 --> 00:11:11,920
Speaker 2: That's right. I think that's called the halo effect. You

233
00:11:12,040 --> 00:11:13,719
Speaker 2: know one good thing about them, and you assume you

234
00:11:13,760 --> 00:11:15,040
Speaker 2: know all the good things about them.

235
00:11:15,120 --> 00:11:18,080
Speaker 1: So let's dig into the physics of tidal locking. What

236
00:11:18,120 --> 00:11:20,120
Speaker 1: it is, what's going on and why I play such

237
00:11:20,120 --> 00:11:22,880
Speaker 1: a big role in what we see in our night sky.

238
00:11:23,160 --> 00:11:25,360
Speaker 1: And I think the first thing to understand is just

239
00:11:25,440 --> 00:11:28,480
Speaker 1: like the geometry of what's going on. Obviously, the Moon

240
00:11:28,800 --> 00:11:32,120
Speaker 1: is orbiting the Earth, and the Earth is spinning, and

241
00:11:32,200 --> 00:11:34,200
Speaker 1: the Moon is spinning around the Earth, and the Moon

242
00:11:34,280 --> 00:11:37,079
Speaker 1: is also spinning on its axis. So there's sort of

243
00:11:37,200 --> 00:11:39,480
Speaker 1: a lot of spinning going on. But you got to

244
00:11:39,520 --> 00:11:41,800
Speaker 1: get all that spinning in your head to understand, like

245
00:11:41,920 --> 00:11:44,640
Speaker 1: why we only see one side of the moon.

246
00:11:44,920 --> 00:11:48,640
Speaker 2: Yes, so I am staring directly ahead trying to picture everything,

247
00:11:48,760 --> 00:11:50,800
Speaker 2: So go ahead, what should I be imagining?

248
00:11:51,840 --> 00:11:54,439
Speaker 1: So first, just put yourself on the Earth and forget

249
00:11:54,440 --> 00:11:56,480
Speaker 1: the fact that the Earth is spinning, and just move

250
00:11:56,559 --> 00:11:59,480
Speaker 1: the Moon around the Earth in your mind and imagine

251
00:11:59,480 --> 00:12:01,320
Speaker 1: the Moon is like a shoe or something. If the

252
00:12:01,360 --> 00:12:03,960
Speaker 1: Moon is not spinning, it's just orbiting the Earth, then

253
00:12:04,040 --> 00:12:06,200
Speaker 1: the Earth is going to see different sides of the shoe.

254
00:12:06,240 --> 00:12:07,560
Speaker 1: It's going to see the back of the shoe, it's

255
00:12:07,600 --> 00:12:09,679
Speaker 1: going to see the front of the shoe, because as

256
00:12:09,720 --> 00:12:12,480
Speaker 1: the shoe moves around the Earth, different sides of it

257
00:12:12,559 --> 00:12:15,000
Speaker 1: are going to be closer to the Earth or closer

258
00:12:15,040 --> 00:12:15,880
Speaker 1: to outer space.

259
00:12:16,120 --> 00:12:17,640
Speaker 2: So the shoe is not rotating either.

260
00:12:17,800 --> 00:12:20,000
Speaker 1: That's right. So first the shoe is not rotating, and

261
00:12:20,040 --> 00:12:21,319
Speaker 1: so we see one side of it, and then we

262
00:12:21,360 --> 00:12:23,559
Speaker 1: see the other side of it. So if the shoe

263
00:12:23,720 --> 00:12:25,960
Speaker 1: or the moon or whatever is not spinning, then you

264
00:12:25,960 --> 00:12:28,440
Speaker 1: would see different sides of it. Right now, the moon,

265
00:12:28,440 --> 00:12:31,280
Speaker 1: of course, is spinning. It's spinning on its axis. But

266
00:12:31,360 --> 00:12:33,640
Speaker 1: if it was spinning at some random rate, like really

267
00:12:33,679 --> 00:12:36,360
Speaker 1: really fast or really really slow, you would still see

268
00:12:36,400 --> 00:12:38,599
Speaker 1: both sides of it, because eventually it would spin in

269
00:12:38,679 --> 00:12:41,520
Speaker 1: a way that revealed every part of the moon. The

270
00:12:41,559 --> 00:12:44,160
Speaker 1: only way for us to not be able to see

271
00:12:44,200 --> 00:12:46,760
Speaker 1: part of the moon is for its spin to be

272
00:12:46,880 --> 00:12:49,840
Speaker 1: perfectly syncd up with its orbit, so that as it

273
00:12:49,920 --> 00:12:52,480
Speaker 1: goes around the Earth, it turns just the right a

274
00:12:52,520 --> 00:12:55,560
Speaker 1: mount every second, so the same side of it is

275
00:12:55,640 --> 00:12:58,440
Speaker 1: always facing the Earth, like if the back side of

276
00:12:58,480 --> 00:13:01,320
Speaker 1: the shoe is always fa the Earth, because the shoe

277
00:13:01,360 --> 00:13:03,480
Speaker 1: itself is spinning at just the right rate as it

278
00:13:03,520 --> 00:13:04,880
Speaker 1: goes around the Earth.

279
00:13:04,760 --> 00:13:07,680
Speaker 2: And everyone on every part of the Earth is always

280
00:13:07,679 --> 00:13:09,760
Speaker 2: seeing the same side of the Moon. Right, It's not

281
00:13:09,840 --> 00:13:11,760
Speaker 2: like you know, in the US you see one side

282
00:13:11,760 --> 00:13:13,800
Speaker 2: and in China you see the other side, or right,

283
00:13:13,880 --> 00:13:15,079
Speaker 2: You're always seeing the same side.

284
00:13:15,160 --> 00:13:17,480
Speaker 1: That's right. The same side of the Moon is always

285
00:13:17,520 --> 00:13:19,760
Speaker 1: closer to the Earth, and the other side of the

286
00:13:19,760 --> 00:13:22,280
Speaker 1: Moon that we call the far side, which I assume

287
00:13:22,480 --> 00:13:24,480
Speaker 1: is the origin of the name of the far side

288
00:13:24,480 --> 00:13:28,520
Speaker 1: and comic, it is always facing outer space. And this

289
00:13:28,600 --> 00:13:31,600
Speaker 1: is the sort of coincidence we were talking about. Like these

290
00:13:31,640 --> 00:13:34,400
Speaker 1: two numbers, the rate at which the Moon goes around

291
00:13:34,400 --> 00:13:36,640
Speaker 1: the Earth and the rate at which the Moon spins

292
00:13:36,720 --> 00:13:40,320
Speaker 1: around its axis have to be perfectly synced up to

293
00:13:40,360 --> 00:13:41,160
Speaker 1: get this effect.

294
00:13:41,360 --> 00:13:44,040
Speaker 2: And why are they perfectly syncd up? Is this one

295
00:13:44,080 --> 00:13:46,720
Speaker 2: of the few instances in which we have something special

296
00:13:46,800 --> 00:13:49,640
Speaker 2: going on and they just happen to sync up. Or

297
00:13:49,840 --> 00:13:52,680
Speaker 2: are we just like every other moon because this happens

298
00:13:52,679 --> 00:13:53,240
Speaker 2: all the time.

299
00:13:54,559 --> 00:13:57,280
Speaker 1: So it's not that special and it's not a coincidence,

300
00:13:57,360 --> 00:14:00,439
Speaker 1: but it's not something that's always happened. Like, to get

301
00:14:00,440 --> 00:14:02,760
Speaker 1: into it, you have to understand the history of the

302
00:14:02,800 --> 00:14:05,040
Speaker 1: formation of the Moon, like how did it get made,

303
00:14:05,280 --> 00:14:08,440
Speaker 1: how was it spinning originally, and then how has that changed?

304
00:14:08,520 --> 00:14:10,840
Speaker 1: You know, our moon is not just like some object

305
00:14:10,920 --> 00:14:13,600
Speaker 1: that we captured as it was flying by. We think

306
00:14:13,600 --> 00:14:17,200
Speaker 1: that the Moon actually comes from a huge collision something

307
00:14:17,280 --> 00:14:20,320
Speaker 1: like one hundred million years after the Earth was formed,

308
00:14:20,320 --> 00:14:23,800
Speaker 1: so we're talking like four point four billion years ago.

309
00:14:24,080 --> 00:14:27,120
Speaker 1: You have some like very hot proto Earth. It got

310
00:14:27,160 --> 00:14:32,040
Speaker 1: slammed into by some giant Mars sized planet they called Fea,

311
00:14:32,520 --> 00:14:35,200
Speaker 1: And so you're talking about a huge collision like Earth

312
00:14:35,320 --> 00:14:40,000
Speaker 1: versus Mars in space and both objects are essentially vaporized.

313
00:14:40,280 --> 00:14:42,400
Speaker 2: But we still have thirst in the moon.

314
00:14:43,920 --> 00:14:47,320
Speaker 1: You're like, how do that to current reality? You know,

315
00:14:47,400 --> 00:14:51,000
Speaker 1: you're exactly right, it got vaporized, but then it coalesced. Right.

316
00:14:51,120 --> 00:14:54,320
Speaker 1: Gravity is very very patient, and so even though all

317
00:14:54,360 --> 00:14:56,160
Speaker 1: of its original work in the first one hundred million

318
00:14:56,200 --> 00:14:59,120
Speaker 1: years was ruined by this collision. It got back to

319
00:14:59,160 --> 00:15:01,800
Speaker 1: work and it pulled those blobs together and it made

320
00:15:02,000 --> 00:15:04,760
Speaker 1: two new blobs, one that formed the Earth, and then

321
00:15:04,800 --> 00:15:07,160
Speaker 1: a big ring around the Earth, like a ring of

322
00:15:07,200 --> 00:15:10,400
Speaker 1: debris that was spinning sort of too fast around the

323
00:15:10,400 --> 00:15:13,440
Speaker 1: Earth to fall into the central clump, which formed this

324
00:15:13,560 --> 00:15:15,480
Speaker 1: like huge spray of material.

325
00:15:15,800 --> 00:15:17,680
Speaker 2: All right, So, and that's why the Moon's made out

326
00:15:17,680 --> 00:15:19,160
Speaker 2: of the same stuff the Earth is made out of.

327
00:15:19,360 --> 00:15:22,160
Speaker 1: Exactly when we visited the Earth first and we sampled it,

328
00:15:22,360 --> 00:15:25,320
Speaker 1: people were surprised to discover that it's basically the same

329
00:15:25,400 --> 00:15:27,920
Speaker 1: mixture of stuff as the Earth. It's not like a

330
00:15:28,040 --> 00:15:31,120
Speaker 1: different Solar System body that was formed in another place,

331
00:15:31,160 --> 00:15:33,320
Speaker 1: and so it has a different mixture of like ices

332
00:15:33,400 --> 00:15:36,280
Speaker 1: and rocks and different isotopes and stuff. It's basically made

333
00:15:36,320 --> 00:15:38,120
Speaker 1: out of the same stuff as the Earth. And that's

334
00:15:38,120 --> 00:15:42,040
Speaker 1: because it comes from the same mixture of those two planets.

335
00:15:42,520 --> 00:15:44,960
Speaker 1: Like it was the same vaporized blob of stuff, and

336
00:15:45,080 --> 00:15:46,680
Speaker 1: some of it fell in towards the Earth, and the

337
00:15:46,680 --> 00:15:49,160
Speaker 1: stuff that was spinning around sort of too fast ended

338
00:15:49,240 --> 00:15:52,240
Speaker 1: up in this big debris ring. But then gravity pulled

339
00:15:52,280 --> 00:15:53,800
Speaker 1: that together into a moon.

340
00:15:54,160 --> 00:15:56,560
Speaker 2: Did we have this hypothesis before we went to the

341
00:15:56,560 --> 00:15:58,560
Speaker 2: Moon and found what it was made of, or did

342
00:15:58,640 --> 00:16:02,160
Speaker 2: going to the Moon and physically collecting samples give us

343
00:16:02,200 --> 00:16:04,960
Speaker 2: this hypothesis when we were like, whoa, it's the same stuff.

344
00:16:06,120 --> 00:16:08,400
Speaker 1: This hypothesis has been around for a while, but it

345
00:16:08,440 --> 00:16:10,840
Speaker 1: really became the favorite once we went to the Moon,

346
00:16:11,280 --> 00:16:14,400
Speaker 1: and also once we understood something about the Moon's inner core.

347
00:16:14,800 --> 00:16:17,640
Speaker 1: The Moon has sort of a small iron core, smaller

348
00:16:17,640 --> 00:16:20,480
Speaker 1: than you would expect, and the hypothesis is that a

349
00:16:20,520 --> 00:16:23,440
Speaker 1: lot of that iron was probably lost from when the

350
00:16:23,480 --> 00:16:26,000
Speaker 1: impactor hit the proto Earth, and some of that was

351
00:16:26,120 --> 00:16:28,320
Speaker 1: like melted and vaporized, and so it would have a

352
00:16:28,360 --> 00:16:31,440
Speaker 1: bigger iron core otherwise. This became a much more popular

353
00:16:31,560 --> 00:16:34,080
Speaker 1: hypothesis after we went to the Moon and visited and

354
00:16:34,160 --> 00:16:36,320
Speaker 1: understood what it was made out of. And there's a

355
00:16:36,320 --> 00:16:38,720
Speaker 1: lot of really interesting physics there that's relevant to it,

356
00:16:38,800 --> 00:16:41,760
Speaker 1: Like why doesn't it all just collapse into a planet, right,

357
00:16:41,920 --> 00:16:44,680
Speaker 1: Why doesn't it all just become one huge giant planet.

358
00:16:44,720 --> 00:16:46,760
Speaker 1: How come part of it ended up as a ring?

359
00:16:46,840 --> 00:16:48,960
Speaker 1: And that's just because you know, the whole thing is

360
00:16:49,000 --> 00:16:51,600
Speaker 1: spinning and a lot of it has angular momentum, and

361
00:16:51,680 --> 00:16:54,240
Speaker 1: so some stuff was just moving too fast to fall

362
00:16:54,240 --> 00:16:57,000
Speaker 1: in the way, like the moon now is moving too

363
00:16:57,040 --> 00:16:59,640
Speaker 1: fast to fall into the Earth. It's all about that.

364
00:17:00,520 --> 00:17:02,960
Speaker 1: And then when that stuff gathered together into a moon,

365
00:17:03,160 --> 00:17:07,720
Speaker 1: that stuff was spinning. So the moon had some original spin, right,

366
00:17:07,760 --> 00:17:10,239
Speaker 1: that came from the spinning motion of all of that

367
00:17:10,359 --> 00:17:14,000
Speaker 1: stuff after the vaporization. And we think that spin rate

368
00:17:14,080 --> 00:17:17,560
Speaker 1: originally was much much higher than it is today. So

369
00:17:17,600 --> 00:17:20,640
Speaker 1: the Moon used to be spinning faster than it is now.

370
00:17:20,800 --> 00:17:23,640
Speaker 2: Was there this is maybe an unfair question. Was there

371
00:17:23,680 --> 00:17:27,280
Speaker 2: anything alive on Earth when it was spinning fast enough

372
00:17:27,280 --> 00:17:29,560
Speaker 2: that sometimes you'd see what is now the far side

373
00:17:29,560 --> 00:17:32,439
Speaker 2: of the moon. So like dinosaurs probably never saw the

374
00:17:32,440 --> 00:17:34,600
Speaker 2: far side of the moon, but did like the first

375
00:17:34,640 --> 00:17:36,560
Speaker 2: bacteria see the far side of the Moon. I mean,

376
00:17:36,560 --> 00:17:39,080
Speaker 2: I'm sure they don't see anything that far away, but

377
00:17:39,160 --> 00:17:40,119
Speaker 2: you know, could they have.

378
00:17:40,640 --> 00:17:43,560
Speaker 1: Yeah, it's possible. We don't really know exactly how old

379
00:17:43,640 --> 00:17:46,760
Speaker 1: life is on Earth, but it stretches back billions of years, right,

380
00:17:47,240 --> 00:17:49,800
Speaker 1: And so it's possible that there are critters that have

381
00:17:49,880 --> 00:17:52,240
Speaker 1: lived on Earth that have seen other parts of the Moon.

382
00:17:52,280 --> 00:17:55,240
Speaker 1: That's a very cool thought. Because the Earth has been

383
00:17:55,359 --> 00:17:59,720
Speaker 1: gradually slowing down the Moon's spin little by a little

384
00:17:59,720 --> 00:18:03,679
Speaker 1: every year, and the opposite is also true. But you know,

385
00:18:03,840 --> 00:18:08,080
Speaker 1: until nineteen fifty nine, no human had ever seen the

386
00:18:08,119 --> 00:18:10,719
Speaker 1: backside of the Moon. It was this like dark spot

387
00:18:10,800 --> 00:18:13,040
Speaker 1: in our vision that we just couldn't see, no matter

388
00:18:13,280 --> 00:18:15,399
Speaker 1: how many thousands of years we've been staring up at

389
00:18:15,440 --> 00:18:18,040
Speaker 1: the Moon. Nobody had ever laid eyes on the backside

390
00:18:18,119 --> 00:18:21,920
Speaker 1: until nineteen fifty nine, which feels really recent.

391
00:18:21,880 --> 00:18:23,399
Speaker 2: Right, And the Soviets did.

392
00:18:23,280 --> 00:18:25,040
Speaker 1: It, right, Yeah, they certainly did.

393
00:18:25,440 --> 00:18:27,840
Speaker 2: Yeah, they beat us there with the lunar program. Their

394
00:18:27,880 --> 00:18:29,760
Speaker 2: third one made it there. I think the first two

395
00:18:30,000 --> 00:18:32,480
Speaker 2: maybe blew up. That was a thing that happened a

396
00:18:32,520 --> 00:18:36,600
Speaker 2: lot for the Soviets. But anyway, so.

397
00:18:36,640 --> 00:18:38,880
Speaker 1: Sorry, no, there's a really fun set of stories there.

398
00:18:39,040 --> 00:18:41,439
Speaker 1: Maybe you know about because of your book research, that

399
00:18:41,480 --> 00:18:43,320
Speaker 1: the Soviets were there first, and so they got to

400
00:18:43,440 --> 00:18:45,240
Speaker 1: name a lot of stuff on the far side of

401
00:18:45,280 --> 00:18:47,600
Speaker 1: the Moon first. So they have all these Russian names

402
00:18:48,080 --> 00:18:51,119
Speaker 1: and that like really annoyed the Americans at the time.

403
00:18:51,359 --> 00:18:54,800
Speaker 1: And then you know, later this International Astronomical Union took

404
00:18:54,840 --> 00:18:56,840
Speaker 1: over the naming, so it wasn't all just you know,

405
00:18:57,200 --> 00:18:59,159
Speaker 1: named after kinds of vodka or whatever.

406
00:18:59,480 --> 00:19:05,280
Speaker 2: All now that's an unfair stereotype. Did the IAU change

407
00:19:05,359 --> 00:19:07,920
Speaker 2: any of the names that the Soviet program had put

408
00:19:07,960 --> 00:19:10,640
Speaker 2: in place, or they just like stopped the Soviets from

409
00:19:10,680 --> 00:19:11,600
Speaker 2: doing any more naming.

410
00:19:11,960 --> 00:19:13,600
Speaker 1: I think they just stopped them. And there's a lot

411
00:19:13,640 --> 00:19:16,359
Speaker 1: of respect, I think for the people who discover something

412
00:19:16,440 --> 00:19:18,520
Speaker 1: to name it. But then I think that the Soviets

413
00:19:18,520 --> 00:19:20,520
Speaker 1: were so far ahead that they didn't want them to

414
00:19:20,560 --> 00:19:23,520
Speaker 1: just like name the whole thing after their favorite Soviet

415
00:19:23,560 --> 00:19:24,639
Speaker 1: flower or whatever.

416
00:19:24,880 --> 00:19:28,000
Speaker 2: Thank, yes, there we go. That's good. That's good. I

417
00:19:28,000 --> 00:19:30,440
Speaker 2: think there is like a Gagarian and seas or something

418
00:19:30,520 --> 00:19:33,000
Speaker 2: like them. All Right, so we're gonna take a quick

419
00:19:33,000 --> 00:19:34,919
Speaker 2: break and then we'll talk about what they found on

420
00:19:34,960 --> 00:19:49,399
Speaker 2: the far side of the moon. The first time we

421
00:19:49,440 --> 00:19:50,680
Speaker 2: got to see the far side of the moon was

422
00:19:50,760 --> 00:19:54,640
Speaker 2: nineteen fifty nine. Not too long after that, the Apollo

423
00:19:54,760 --> 00:19:57,400
Speaker 2: astronauts were flying around the Moon and got to see

424
00:19:57,440 --> 00:20:00,399
Speaker 2: the far side. What kinds of things were on the

425
00:20:00,400 --> 00:20:02,080
Speaker 2: far side to see, Daniel.

426
00:20:01,880 --> 00:20:04,920
Speaker 1: Well, you know, in research, it's always exciting to see

427
00:20:04,920 --> 00:20:07,320
Speaker 1: something nobody's ever seen before because you don't know what's

428
00:20:07,359 --> 00:20:09,119
Speaker 1: going to be there. Right, Maybe it's like a crashed

429
00:20:09,160 --> 00:20:13,160
Speaker 1: alien battleship or some weird new geological formation. Right, your

430
00:20:13,160 --> 00:20:16,160
Speaker 1: imagination goes crazy when you're first landing on a spot

431
00:20:16,200 --> 00:20:19,000
Speaker 1: and seeing something no human has ever seen before. But

432
00:20:19,200 --> 00:20:22,560
Speaker 1: you know, in research, discoveries never guaranteed. Just because you

433
00:20:22,720 --> 00:20:25,879
Speaker 1: land on new shores doesn't mean you find something fascinating.

434
00:20:25,960 --> 00:20:28,040
Speaker 1: And in this case, basically we found that the far

435
00:20:28,119 --> 00:20:30,400
Speaker 1: side of the Moon has more rocks and more dust,

436
00:20:30,600 --> 00:20:33,160
Speaker 1: and it's not even very different from the front side

437
00:20:33,160 --> 00:20:35,439
Speaker 1: of the Moon. I mean there are more craters, there

438
00:20:35,440 --> 00:20:38,800
Speaker 1: are fewer of these like seas, these lunar lava flows,

439
00:20:38,960 --> 00:20:40,880
Speaker 1: but all in all, it's not that exciting.

440
00:20:41,200 --> 00:20:45,520
Speaker 2: Yeah, that's the moon, good old, dependable Moon.

441
00:20:46,040 --> 00:20:49,680
Speaker 1: And the first time anybody actually landed there was twenty nineteen,

442
00:20:49,920 --> 00:20:52,240
Speaker 1: like just a few years ago the Chinese put a

443
00:20:52,320 --> 00:20:54,800
Speaker 1: lander down and started to do a bunch of experiments.

444
00:20:55,160 --> 00:20:57,680
Speaker 1: So it's only recently we started to explore it in detail.

445
00:20:57,720 --> 00:20:59,879
Speaker 1: So you know, there's still hope to find that crashed

446
00:21:00,040 --> 00:21:01,359
Speaker 1: alien battleship or.

447
00:21:01,280 --> 00:21:04,240
Speaker 2: The aliens might be living in a lavatude. We could

448
00:21:04,240 --> 00:21:06,680
Speaker 2: find something even more exciting than what you've imagined.

449
00:21:06,840 --> 00:21:09,679
Speaker 1: Yeah, maybe so, Or maybe we could build something that

450
00:21:09,760 --> 00:21:12,920
Speaker 1: future aliens could land and discover for themselves, like people

451
00:21:13,000 --> 00:21:17,320
Speaker 1: are proposing building radio telescopes on the far side of

452
00:21:17,359 --> 00:21:20,840
Speaker 1: the moon looking out into space, because then you'd have

453
00:21:20,880 --> 00:21:23,480
Speaker 1: the whole moon to shield you from the noise of

454
00:21:23,520 --> 00:21:24,000
Speaker 1: the Earth.

455
00:21:24,200 --> 00:21:28,119
Speaker 2: From my perspective, that's an interesting prospect geopolitically, because if

456
00:21:28,119 --> 00:21:30,399
Speaker 2: you built one of those radio telescopes, it wouldn't work

457
00:21:30,440 --> 00:21:32,800
Speaker 2: as well if people put other stuff on that side

458
00:21:32,800 --> 00:21:36,720
Speaker 2: of the moon. So now there's like competition for that space.

459
00:21:36,800 --> 00:21:38,919
Speaker 2: And can you tell someone they can't use the far

460
00:21:39,000 --> 00:21:41,800
Speaker 2: side of the moon because your radio telescope is there. Anyway,

461
00:21:41,840 --> 00:21:43,720
Speaker 2: These things are complicated, but yes, it would be a

462
00:21:43,720 --> 00:21:45,119
Speaker 2: good place for a radio telescope.

463
00:21:45,240 --> 00:21:46,919
Speaker 1: Sounds like the kind of things a bunch of lawyers

464
00:21:46,920 --> 00:21:48,720
Speaker 1: in a conference room are going to hash out one day.

465
00:21:48,960 --> 00:21:50,359
Speaker 1: So the far side of the Moon is not that

466
00:21:50,600 --> 00:21:53,440
Speaker 1: exciting on its own, but it is fascinating to understand

467
00:21:53,560 --> 00:21:56,000
Speaker 1: why there is a far side of the moon. Before

468
00:21:56,000 --> 00:21:57,920
Speaker 1: we dig into that, I just want to clarify something

469
00:21:57,960 --> 00:22:01,480
Speaker 1: that's a common misunderstanding, which the difference between the far

470
00:22:01,600 --> 00:22:03,920
Speaker 1: side of the Moon and the dark side of the moon.

471
00:22:04,320 --> 00:22:05,720
Speaker 1: Also the Pink Floyd album.

472
00:22:05,760 --> 00:22:08,320
Speaker 2: I don't think anyone needs clarification. We all know about that,

473
00:22:09,440 --> 00:22:11,760
Speaker 2: and we've all probably seen the light show if we're

474
00:22:11,800 --> 00:22:13,159
Speaker 2: around forty years old.

475
00:22:13,920 --> 00:22:16,119
Speaker 1: So some people imagine that the far side of the

476
00:22:16,119 --> 00:22:18,240
Speaker 1: moon is also the dark side of the moon, that like,

477
00:22:18,480 --> 00:22:21,119
Speaker 1: this part of the moon never sees sunlight, which is

478
00:22:21,119 --> 00:22:23,639
Speaker 1: definitely not true. The dark side of the moon is

479
00:22:23,680 --> 00:22:25,960
Speaker 1: the side of the moon facing away from the Sun.

480
00:22:26,200 --> 00:22:28,080
Speaker 1: The far side of the moon is the side facing

481
00:22:28,119 --> 00:22:31,320
Speaker 1: away from the Earth, and those two often don't agree.

482
00:22:31,560 --> 00:22:33,119
Speaker 1: So when we have a full moon, the sun is

483
00:22:33,119 --> 00:22:36,240
Speaker 1: illuminating the entire side of the Moon that we are

484
00:22:36,280 --> 00:22:39,960
Speaker 1: seeing because the Sun is sort of behind us in space.

485
00:22:40,200 --> 00:22:42,040
Speaker 1: Then the back side of the moon, the far side

486
00:22:42,040 --> 00:22:44,960
Speaker 1: that we don't see, is also dark. But the opposite

487
00:22:44,960 --> 00:22:47,680
Speaker 1: scenario when the moon is totally dark when we see

488
00:22:47,720 --> 00:22:50,240
Speaker 1: a new moon, and that's because the far side of

489
00:22:50,240 --> 00:22:52,440
Speaker 1: the moon is totally lit up by the sun. Right

490
00:22:52,640 --> 00:22:55,359
Speaker 1: half of the moon is always lit up, it's just

491
00:22:55,400 --> 00:22:58,200
Speaker 1: sometimes not the side that we're seeing, So the far

492
00:22:58,280 --> 00:23:00,520
Speaker 1: side and the dark side are different. It would be

493
00:23:00,600 --> 00:23:03,320
Speaker 1: like a Gary Larsen Pink Floyd crossover event when they meet.

494
00:23:03,480 --> 00:23:05,320
Speaker 2: I'm pretty sure if you play Dark Side of the

495
00:23:05,320 --> 00:23:09,640
Speaker 2: Moon backwards it explains that.

496
00:23:09,640 --> 00:23:12,199
Speaker 1: That's how you understand the far side cartoons, right, you

497
00:23:12,240 --> 00:23:14,240
Speaker 1: have to listen to the dark side of the moon backwards.

498
00:23:14,320 --> 00:23:17,040
Speaker 2: Yeah, there was a lot of cross talk between the

499
00:23:17,240 --> 00:23:22,080
Speaker 2: arts back then. Okay, so how is this happening. The

500
00:23:22,080 --> 00:23:25,000
Speaker 2: moon was going faster, you said, and it's been slowing down.

501
00:23:25,960 --> 00:23:29,040
Speaker 2: Why has it slowed down to be exactly the same

502
00:23:29,240 --> 00:23:31,359
Speaker 2: rotation rate and stuff? What's going on?

503
00:23:31,520 --> 00:23:34,480
Speaker 1: So it's not a coincidence, right. Physics seems to like

504
00:23:34,560 --> 00:23:38,480
Speaker 1: this scenario, and it's called tidal locking because it's connected

505
00:23:38,520 --> 00:23:41,520
Speaker 1: to the concept of tidal forces, which are in effect

506
00:23:41,560 --> 00:23:44,040
Speaker 1: we see all the time in gravity. And it sounds complicated,

507
00:23:44,040 --> 00:23:46,080
Speaker 1: but it's really pretty simple. The only thing you really

508
00:23:46,160 --> 00:23:50,119
Speaker 1: have to understand is that gravity gets weaker as distances

509
00:23:50,200 --> 00:23:52,120
Speaker 1: get longer. So if you're further away from the Sun,

510
00:23:52,160 --> 00:23:54,439
Speaker 1: it's gravity is less powerful. As you get closer to

511
00:23:54,480 --> 00:23:57,200
Speaker 1: the Sun, it's gravity is more powerful. That makes sense.

512
00:23:57,560 --> 00:24:00,479
Speaker 1: But now imagine you're a pretty big object. Part of

513
00:24:00,480 --> 00:24:03,280
Speaker 1: you is closer to the Sun than another part, then

514
00:24:03,400 --> 00:24:06,159
Speaker 1: part of you is going to feel stronger gravity than

515
00:24:06,200 --> 00:24:08,240
Speaker 1: the other part. And this happens all the time, Like

516
00:24:08,280 --> 00:24:10,359
Speaker 1: if you are standing on the surface of the Earth,

517
00:24:10,680 --> 00:24:13,520
Speaker 1: then the Earth is pulling on your legs harder than

518
00:24:13,560 --> 00:24:16,159
Speaker 1: it's pulling on your head, right, and so that's a

519
00:24:16,200 --> 00:24:19,800
Speaker 1: tidal force because there's a difference there. You can actually

520
00:24:19,840 --> 00:24:21,600
Speaker 1: think about the Earth is sort of like trying to

521
00:24:21,640 --> 00:24:23,440
Speaker 1: pull your head off of your body.

522
00:24:23,680 --> 00:24:26,000
Speaker 2: Is this like many spaghetification?

523
00:24:26,359 --> 00:24:30,040
Speaker 1: Yes, exactly, when it's very powerful. When it's more powerful,

524
00:24:30,280 --> 00:24:33,520
Speaker 1: then the force is holding an object together, that's spaghetification.

525
00:24:33,640 --> 00:24:36,240
Speaker 1: And so when you get near a black hole, for example,

526
00:24:36,240 --> 00:24:39,600
Speaker 1: gravity is super powerful, and the difference between the gravity

527
00:24:39,640 --> 00:24:42,639
Speaker 1: at your feet and your head is much more dramatic

528
00:24:42,840 --> 00:24:45,080
Speaker 1: and much more powerful than the force is holding your

529
00:24:45,119 --> 00:24:47,920
Speaker 1: head on your body, and so it's effectively natural decapitation

530
00:24:48,320 --> 00:24:49,280
Speaker 1: or spaghetification.

531
00:24:49,640 --> 00:24:53,040
Speaker 2: But lucky for us, instead of death, we get.

532
00:24:52,800 --> 00:24:56,479
Speaker 1: The tie exactly, so you don't have to worry about that,

533
00:24:56,560 --> 00:24:58,760
Speaker 1: because the difference of the force of gravity on your

534
00:24:58,760 --> 00:25:01,160
Speaker 1: feet and on your head is very gentle, and your

535
00:25:01,200 --> 00:25:04,479
Speaker 1: neck is very powerful in comparison. But the moon is

536
00:25:04,560 --> 00:25:07,640
Speaker 1: pretty big, and so the difference between the gravitational force

537
00:25:07,680 --> 00:25:09,560
Speaker 1: on one side of the moon and on the other

538
00:25:10,240 --> 00:25:12,679
Speaker 1: is much stronger. And so what happens is that the

539
00:25:12,720 --> 00:25:16,000
Speaker 1: Earth basically turns the Moon a little bit into a football.

540
00:25:16,480 --> 00:25:18,760
Speaker 1: It like makes it a little bit all blong, because

541
00:25:18,800 --> 00:25:20,960
Speaker 1: it pulls on the closer bits more powerfully, and it

542
00:25:21,000 --> 00:25:23,320
Speaker 1: pulls on the further bits more gently, and has the

543
00:25:23,320 --> 00:25:25,919
Speaker 1: effect of sort of like stretching it out, making it

544
00:25:26,040 --> 00:25:28,479
Speaker 1: longer like a football instead of like a sphere.

545
00:25:28,760 --> 00:25:30,399
Speaker 2: This is another one of those things I'm surprised we

546
00:25:30,400 --> 00:25:32,080
Speaker 2: ever figured out, because when I look at the Moon,

547
00:25:32,119 --> 00:25:33,919
Speaker 2: I would not think football.

548
00:25:34,160 --> 00:25:36,320
Speaker 1: It's a subtle effect, right, It looks like a sphere,

549
00:25:36,320 --> 00:25:38,920
Speaker 1: but is slightly distorted by the gravity of the Earth,

550
00:25:39,080 --> 00:25:41,400
Speaker 1: and that has a big impact on how it spins,

551
00:25:41,480 --> 00:25:44,560
Speaker 1: because now it has a gravitational preference to be aligned

552
00:25:44,560 --> 00:25:47,080
Speaker 1: a certain way with the Earth. If it was a

553
00:25:47,080 --> 00:25:49,920
Speaker 1: perfect sphere, then the gravity on the object wouldn't change

554
00:25:49,960 --> 00:25:52,800
Speaker 1: as it spins. But if it has a bulge, then

555
00:25:52,840 --> 00:25:56,560
Speaker 1: gravity prefers that bulge to be aligned with the object,

556
00:25:56,640 --> 00:25:59,000
Speaker 1: sort of like gravity has a handle now on the

557
00:25:59,040 --> 00:26:02,760
Speaker 1: Moon to pull that bulge, so one point is towards

558
00:26:02,760 --> 00:26:04,720
Speaker 1: the Earth and one point is away from the Earth.

559
00:26:04,800 --> 00:26:08,879
Speaker 1: That's like gravitationally less energetic a configuration than having the

560
00:26:08,920 --> 00:26:09,680
Speaker 1: whole thing spin.

561
00:26:10,359 --> 00:26:12,000
Speaker 2: All right, Okay, so I'm trying to wrap my head

562
00:26:12,040 --> 00:26:15,439
Speaker 2: around this, and picturing things in my head is not

563
00:26:15,560 --> 00:26:17,480
Speaker 2: one of my stronger suits. But here we go. Okay,

564
00:26:17,480 --> 00:26:19,280
Speaker 2: so we prefer to have a grip on the handle.

565
00:26:19,640 --> 00:26:23,920
Speaker 2: Does the moon spin at a not constant speed where

566
00:26:23,960 --> 00:26:26,080
Speaker 2: like we hold on to the handle for a little longer.

567
00:26:26,280 --> 00:26:28,320
Speaker 2: I don't think that's what you're saying, And so what

568
00:26:28,359 --> 00:26:29,000
Speaker 2: am I missing?

569
00:26:29,200 --> 00:26:31,679
Speaker 1: So what happened initially is that the Earth started to

570
00:26:31,720 --> 00:26:34,680
Speaker 1: form these bulges on the Moon, and then the Moon

571
00:26:34,760 --> 00:26:37,480
Speaker 1: was spinning, and so these bulges were like ripples through

572
00:26:37,520 --> 00:26:40,400
Speaker 1: the surface of the Moon. There were like these waves

573
00:26:40,440 --> 00:26:43,320
Speaker 1: that pass through the Moon. But Earth is also pulling

574
00:26:43,359 --> 00:26:46,359
Speaker 1: on those bulges, right Like, if the Moon has a bulge,

575
00:26:46,400 --> 00:26:48,440
Speaker 1: it's like a football, and then it starts to spin

576
00:26:48,480 --> 00:26:51,000
Speaker 1: away from the Earth. The Earth is going to pull

577
00:26:51,240 --> 00:26:53,639
Speaker 1: on that nearest point a little bit and try to

578
00:26:53,680 --> 00:26:56,400
Speaker 1: pull it back, and that effectively moves the bulge through

579
00:26:56,440 --> 00:26:58,320
Speaker 1: the surface of the Moon a little bit, and so

580
00:26:58,400 --> 00:27:01,239
Speaker 1: that slows down the rotation of the Moon a little bit,

581
00:27:01,240 --> 00:27:03,320
Speaker 1: because the Earth is like tugging trying to pull that

582
00:27:03,359 --> 00:27:06,440
Speaker 1: point back towards it, and so that slows the moon

583
00:27:06,480 --> 00:27:09,720
Speaker 1: down a little bit. And eventually the Moon settles into

584
00:27:09,800 --> 00:27:13,320
Speaker 1: a pattern where these waves the bulge doesn't travel over

585
00:27:13,359 --> 00:27:17,200
Speaker 1: its surface anymore, like settles into one location. And that's

586
00:27:17,240 --> 00:27:18,520
Speaker 1: what the Earth prefers.

587
00:27:18,160 --> 00:27:20,199
Speaker 2: Gravitationally, Okay, I'm with you.

588
00:27:20,359 --> 00:27:23,160
Speaker 1: And so that's how gravity makes the Moon a little

589
00:27:23,200 --> 00:27:26,760
Speaker 1: bit pointy and also slows down its spin. It's like

590
00:27:26,880 --> 00:27:29,879
Speaker 1: stealing some of its energy a little bit to slow

591
00:27:29,960 --> 00:27:30,920
Speaker 1: down its spin.

592
00:27:31,200 --> 00:27:34,800
Speaker 2: But why does its spin get slowed down to exactly

593
00:27:35,000 --> 00:27:37,679
Speaker 2: the right amount, Like it seems like that should just

594
00:27:37,680 --> 00:27:39,040
Speaker 2: slow things down in general.

595
00:27:39,359 --> 00:27:41,720
Speaker 1: It does. It slows things down in general, but at

596
00:27:41,720 --> 00:27:44,080
Speaker 1: some point it starts spinning at just the right speed

597
00:27:44,160 --> 00:27:47,040
Speaker 1: so that the pointy bit is always pointing towards the Earth.

598
00:27:47,400 --> 00:27:49,600
Speaker 1: And then the Earth is happy, and the gravity of

599
00:27:49,640 --> 00:27:52,080
Speaker 1: the Earth no longer wants to slow down the spin

600
00:27:52,240 --> 00:27:54,119
Speaker 1: of the Moon because the point to bit is always

601
00:27:54,160 --> 00:27:56,639
Speaker 1: facing the Earth, and so gravity is happy, because it's

602
00:27:56,680 --> 00:27:59,000
Speaker 1: sort of like a ball rolling to the bottom of

603
00:27:59,040 --> 00:28:02,000
Speaker 1: a valley, happy when it's settled in the bottom of

604
00:28:02,040 --> 00:28:03,760
Speaker 1: the valley. So this is sort of like, you know,

605
00:28:03,800 --> 00:28:05,359
Speaker 1: you let a marble go at the top of a

606
00:28:05,440 --> 00:28:08,000
Speaker 1: hill and it's gonna roll down. It's gonna awesantly pass

607
00:28:08,080 --> 00:28:10,960
Speaker 1: the minimum, but eventually friction and everything it's gonna settle

608
00:28:11,000 --> 00:28:13,400
Speaker 1: down in the minimum, and the same thing happens. There's

609
00:28:13,440 --> 00:28:16,520
Speaker 1: like friction inside the Moon, and the Moon gets heated

610
00:28:16,600 --> 00:28:18,800
Speaker 1: up a little bit by this, and the Moon also

611
00:28:18,920 --> 00:28:21,879
Speaker 1: speeds up in its orbit because there's like conservation of

612
00:28:21,920 --> 00:28:24,720
Speaker 1: angular momentum. So you've slowed down the Moon's spin a

613
00:28:24,760 --> 00:28:27,160
Speaker 1: little bit, and you've sped up its orbit a little bit,

614
00:28:27,200 --> 00:28:29,760
Speaker 1: which is why the Moon's orbital radius is increasing a

615
00:28:29,840 --> 00:28:30,240
Speaker 1: little bit.

616
00:28:30,640 --> 00:28:33,840
Speaker 2: And so how rare is this? Like if Earth were

617
00:28:33,840 --> 00:28:37,520
Speaker 2: a little bit smaller, would this not happen? If there was,

618
00:28:37,640 --> 00:28:40,880
Speaker 2: like if Mars was a little closer, would this not happen?

619
00:28:41,000 --> 00:28:41,080
Speaker 1: Like?

620
00:28:41,240 --> 00:28:43,640
Speaker 2: How lucky are we that it worked out this way?

621
00:28:43,720 --> 00:28:45,800
Speaker 1: We're not that lucky. It's sort of the eventual fate

622
00:28:45,880 --> 00:28:49,120
Speaker 1: of almost every pair of bodies that orbit each other

623
00:28:49,160 --> 00:28:51,400
Speaker 1: for long enough. And in fact, we've done it to

624
00:28:51,440 --> 00:28:54,600
Speaker 1: the Moon, and eventually the Moon will do it to

625
00:28:54,680 --> 00:28:56,960
Speaker 1: the Earth. It's just a slower process.

626
00:28:57,280 --> 00:29:00,959
Speaker 2: Whoa like, how slow? Like are we gonna swallowed up

627
00:29:00,960 --> 00:29:04,080
Speaker 2: by the Sun before it happens? Or is my you know,

628
00:29:04,200 --> 00:29:07,160
Speaker 2: kid gonna see it before they turn eighty.

629
00:29:07,200 --> 00:29:11,080
Speaker 1: Yeah, so the Earth's rotation has already been significantly slowed

630
00:29:11,120 --> 00:29:14,080
Speaker 1: by this effect from the Moon. Over the four billion

631
00:29:14,200 --> 00:29:16,280
Speaker 1: years since the Earth and the Moon were formed, the

632
00:29:16,400 --> 00:29:19,840
Speaker 1: length of an Earth day has lengthened from six hours

633
00:29:20,040 --> 00:29:22,880
Speaker 1: to twenty four hours. So the Moon has made our

634
00:29:23,000 --> 00:29:25,960
Speaker 1: days four times longer. It's slowed down the Earth spin

635
00:29:26,080 --> 00:29:29,720
Speaker 1: by a big factor. And eventually, because the Moon keeps

636
00:29:29,760 --> 00:29:31,640
Speaker 1: tugging on the Earth and making it a little bit

637
00:29:31,680 --> 00:29:34,880
Speaker 1: longer than tugging on that handle as it passes, eventually

638
00:29:34,920 --> 00:29:38,600
Speaker 1: it's gonna make the Earth take forty seven days to spin.

639
00:29:39,080 --> 00:29:41,040
Speaker 1: And at that point, the Earth and the Moon will

640
00:29:41,080 --> 00:29:44,360
Speaker 1: both be tidally locked to each other, and the Moon

641
00:29:44,400 --> 00:29:47,200
Speaker 1: will only ever see the same face of the Earth.

642
00:29:47,520 --> 00:29:50,800
Speaker 2: I don't think that's very nice of the bit. I

643
00:29:51,000 --> 00:29:54,360
Speaker 2: like having days. Ah, so I'm glad that's not gonna

644
00:29:54,360 --> 00:29:55,440
Speaker 2: happen in my lifetime.

645
00:29:55,640 --> 00:29:57,760
Speaker 1: That would be fascinating, right because it would mean that

646
00:29:57,920 --> 00:29:59,640
Speaker 1: half of the Earth would see the Moon and the

647
00:29:59,680 --> 00:30:02,800
Speaker 1: other would never see it. If life evolved in that planet,

648
00:30:02,800 --> 00:30:04,880
Speaker 1: then like half of life wouldn't even know there was

649
00:30:04,920 --> 00:30:05,320
Speaker 1: a moon.

650
00:30:05,800 --> 00:30:07,880
Speaker 2: WHOA, I bet we'd have all sorts of different like

651
00:30:07,960 --> 00:30:10,760
Speaker 2: creation stories. If some of us had moons and some

652
00:30:10,800 --> 00:30:13,680
Speaker 2: of us didn't. That would be that would be fascinating.

653
00:30:13,840 --> 00:30:16,160
Speaker 1: Or imagine being an explorer and like settling around the

654
00:30:16,200 --> 00:30:18,880
Speaker 1: world and then discovering this huge thing floating in your sky.

655
00:30:19,000 --> 00:30:24,400
Speaker 1: You're like, what, that would be crazy, that would be

656
00:30:24,480 --> 00:30:26,640
Speaker 1: super amazing. But you're right, it's going to take a

657
00:30:26,640 --> 00:30:30,040
Speaker 1: long time. And well, before that happens, the Earth is

658
00:30:30,080 --> 00:30:32,360
Speaker 1: going to be eaten by the Sun, which is going

659
00:30:32,440 --> 00:30:34,840
Speaker 1: to end its life cycle in about five billion years,

660
00:30:35,120 --> 00:30:38,120
Speaker 1: turn into a red giant and absorb the Earth. So

661
00:30:38,320 --> 00:30:41,000
Speaker 1: the Moon is not powerful enough to make that happen

662
00:30:41,040 --> 00:30:41,800
Speaker 1: anytime soon.

663
00:30:42,160 --> 00:30:45,440
Speaker 2: Well, on the upbeat topic of the end of our planets,

664
00:30:45,920 --> 00:30:48,240
Speaker 2: let's take a break, and when we come back, you

665
00:30:48,280 --> 00:30:50,640
Speaker 2: can tell us if the other moons on the other

666
00:30:50,720 --> 00:30:53,080
Speaker 2: planets are doing this as well. If I live on Mars,

667
00:30:53,120 --> 00:31:08,960
Speaker 2: am i gonna see all of Phobos or not? Okay,

668
00:31:09,040 --> 00:31:12,640
Speaker 2: we're back. So, Daniel, the question that everybody wants to

669
00:31:12,680 --> 00:31:15,920
Speaker 2: know when we move to Mars, are we going to

670
00:31:16,000 --> 00:31:18,720
Speaker 2: see the far side of Phobos and Demos or what?

671
00:31:19,080 --> 00:31:21,040
Speaker 1: So this is a process that happens all over the

672
00:31:21,080 --> 00:31:24,840
Speaker 1: Solar System and all over the universe. Eventually, gravity will

673
00:31:24,880 --> 00:31:27,880
Speaker 1: do its bit and distort objects from spheres into like

674
00:31:27,960 --> 00:31:31,000
Speaker 1: gentle little footballs. It'll grab on those handles and it

675
00:31:31,000 --> 00:31:33,720
Speaker 1: will hidly lock stuff. And so as we look around

676
00:31:33,760 --> 00:31:36,640
Speaker 1: the Solar System, we notice that all of the big moons,

677
00:31:36,680 --> 00:31:40,680
Speaker 1: all of the twenty round moons that exist around planets,

678
00:31:40,920 --> 00:31:43,680
Speaker 1: are all tidally locked to their planet.

679
00:31:44,080 --> 00:31:47,080
Speaker 2: Only the round moons. And what causes the Moon to

680
00:31:47,120 --> 00:31:50,160
Speaker 2: be round, It's that it needs to be a certain size,

681
00:31:50,400 --> 00:31:50,960
Speaker 2: Is that right?

682
00:31:51,200 --> 00:31:53,240
Speaker 1: Yeah, If you're big enough, then gravity is going to

683
00:31:53,240 --> 00:31:56,320
Speaker 1: be powerful enough to pull down any big features, which

684
00:31:56,320 --> 00:31:59,400
Speaker 1: is why, for example, like neutron stars have no features

685
00:31:59,400 --> 00:32:01,720
Speaker 1: on them that are highiher than one millimeter. And the

686
00:32:01,800 --> 00:32:04,280
Speaker 1: larger the gravity, the harder it is to keep a

687
00:32:04,320 --> 00:32:07,200
Speaker 1: stack of stuff from falling down. And so if you're

688
00:32:07,200 --> 00:32:09,120
Speaker 1: a pretty small object, you don't have to be very

689
00:32:09,160 --> 00:32:11,720
Speaker 1: spherical because your gravity's pretty weak. If you're a big

690
00:32:11,800 --> 00:32:14,160
Speaker 1: object like the Moon or the Earth, then you're going

691
00:32:14,240 --> 00:32:17,440
Speaker 1: to end up as a sphere because stuff falls down basically,

692
00:32:17,720 --> 00:32:20,320
Speaker 1: and stuff falls down more when you have more gravity.

693
00:32:20,600 --> 00:32:23,680
Speaker 1: And so these round moons are technically not actually round, right,

694
00:32:23,680 --> 00:32:26,800
Speaker 1: They're a little bit footballish and they're all tidally locked

695
00:32:27,080 --> 00:32:30,000
Speaker 1: to their planet. Most of these also orbit pretty closely

696
00:32:30,040 --> 00:32:32,640
Speaker 1: and so their gravity is pretty powerful. And then example,

697
00:32:32,680 --> 00:32:35,360
Speaker 1: you raise like Phobos and Demos on Mars. These are

698
00:32:35,520 --> 00:32:39,240
Speaker 1: little moons and they're not very large, they're not very round,

699
00:32:39,400 --> 00:32:41,480
Speaker 1: and they're actually spending really really fast. And so while

700
00:32:41,520 --> 00:32:45,280
Speaker 1: Mars is doing its job to try to tidly lock them, Phobos,

701
00:32:45,320 --> 00:32:48,360
Speaker 1: for example, is not yet tidally locked, but it will be.

702
00:32:48,680 --> 00:32:51,200
Speaker 1: It will be eventually. It's going to happen to everybody.

703
00:32:51,520 --> 00:32:54,240
Speaker 2: So we've been talking about moon planets. Has it happened

704
00:32:54,280 --> 00:32:57,920
Speaker 2: to any sun and planets or planets yet?

705
00:32:58,200 --> 00:33:01,040
Speaker 1: Absolutely? It has absolutely will Right, the Sun is the

706
00:33:01,040 --> 00:33:03,400
Speaker 1: most powerful source of gravity in the Solar System, and

707
00:33:03,480 --> 00:33:05,720
Speaker 1: so it's not going to be left out of this party.

708
00:33:06,040 --> 00:33:09,400
Speaker 1: And it has mercury tidly locked in its grasp. But

709
00:33:09,440 --> 00:33:13,320
Speaker 1: it's actually fascinating. It's not quite the same way as

710
00:33:13,360 --> 00:33:16,200
Speaker 1: with the Earth and the Moon because mercury doesn't have

711
00:33:16,280 --> 00:33:19,880
Speaker 1: as circular an orbit. It's much more elliptical. The mercury

712
00:33:19,920 --> 00:33:23,080
Speaker 1: is tightly locked in this weird way. Instead of spinning

713
00:33:23,200 --> 00:33:25,880
Speaker 1: once every time it goes around the Sun, it spins

714
00:33:25,920 --> 00:33:29,280
Speaker 1: three times for every two revolutions around the Sun. And

715
00:33:29,320 --> 00:33:32,040
Speaker 1: this is not something we understood for a while because

716
00:33:32,120 --> 00:33:34,400
Speaker 1: we can't always see Mercury because it's so close to

717
00:33:34,440 --> 00:33:37,240
Speaker 1: the Sun. There's a few spots in its orbit when

718
00:33:37,240 --> 00:33:39,520
Speaker 1: it's like easy to see mercury, and so when people

719
00:33:39,560 --> 00:33:42,520
Speaker 1: were observing Mercury, they were always seeing the same side

720
00:33:42,520 --> 00:33:43,959
Speaker 1: of it, so they thought, oh, it must have been

721
00:33:43,960 --> 00:33:46,360
Speaker 1: a one to one tide locking. And it's only later

722
00:33:46,440 --> 00:33:49,160
Speaker 1: when we got more observations in Mercury did we notice, Oh, no,

723
00:33:49,200 --> 00:33:52,160
Speaker 1: it's doing this even weirder thing. That's because the orbit

724
00:33:52,240 --> 00:33:54,680
Speaker 1: is not circular, and so it can do another little

725
00:33:54,680 --> 00:33:56,920
Speaker 1: bit of spin as it gets further away, and then

726
00:33:56,960 --> 00:33:59,840
Speaker 1: it comes back around, but still it settles into this

727
00:34:00,080 --> 00:34:03,000
Speaker 1: really cool pattern, this three two tidal locking.

728
00:34:03,160 --> 00:34:05,719
Speaker 2: All right, So let's see, my very elderly mother. We're

729
00:34:05,800 --> 00:34:09,760
Speaker 2: on v I'm guessing Mercury is tidally locked in part

730
00:34:09,800 --> 00:34:12,920
Speaker 2: because it's so close to the Sun. So is Venus

731
00:34:13,080 --> 00:34:16,080
Speaker 2: the next closest to being tidally locked or is is

732
00:34:16,160 --> 00:34:17,160
Speaker 2: it tidally locked?

733
00:34:17,239 --> 00:34:20,920
Speaker 1: Also, Venus is next on the list to getting tidly locked.

734
00:34:21,080 --> 00:34:23,839
Speaker 1: It's not yet tidly locked. In fact, Venus has a

735
00:34:23,880 --> 00:34:27,440
Speaker 1: really weird orbit and spin. It takes five hundred and

736
00:34:27,480 --> 00:34:30,359
Speaker 1: eighty three days to go around the Sun, but it

737
00:34:30,400 --> 00:34:33,680
Speaker 1: takes two hundred and twenty four Earth days to rotate.

738
00:34:34,280 --> 00:34:38,080
Speaker 1: So like a Venus year only has one point nine

739
00:34:38,200 --> 00:34:42,319
Speaker 1: Venus days. Like you only see two sunrises and two

740
00:34:42,400 --> 00:34:43,919
Speaker 1: sunsets in a Venus year.

741
00:34:44,280 --> 00:34:46,640
Speaker 2: Huh, But that wouldn't bother you, because Venus would have

742
00:34:46,719 --> 00:34:50,200
Speaker 2: killed you in four or five different ways long before

743
00:34:50,239 --> 00:34:52,120
Speaker 2: you cared about whether the sunrise was coming.

744
00:34:53,160 --> 00:34:55,319
Speaker 1: That's right. But Venus is sot again there right, Like

745
00:34:55,360 --> 00:34:59,160
Speaker 1: it's spin is similar to its orbital period. We actually

746
00:34:59,160 --> 00:35:01,719
Speaker 1: think that's because of a collision that Venus was like

747
00:35:01,840 --> 00:35:05,160
Speaker 1: smacked into by something which really changed its spin. We

748
00:35:05,160 --> 00:35:06,799
Speaker 1: don't think there's been enough time for it to be

749
00:35:06,880 --> 00:35:09,360
Speaker 1: like almost tighly locked by the Sun. It takes a

750
00:35:09,400 --> 00:35:11,799
Speaker 1: much longer time because Venus is so far away from

751
00:35:11,800 --> 00:35:14,479
Speaker 1: the Sun and so small relative to the Sun.

752
00:35:14,760 --> 00:35:20,200
Speaker 2: All right, So we've done moon and planets. We've done

753
00:35:20,280 --> 00:35:26,080
Speaker 2: comparisons between the Sun and the planets. Is there any

754
00:35:26,120 --> 00:35:29,759
Speaker 2: other combination of tidally locked things for us to think about?

755
00:35:29,840 --> 00:35:32,360
Speaker 2: Can asteroids get tidly locked? For example?

756
00:35:32,680 --> 00:35:35,239
Speaker 1: They could, but it's much harder because their gravity is

757
00:35:35,239 --> 00:35:38,160
Speaker 1: so weak. Another really fascinating thing to look at are

758
00:35:38,320 --> 00:35:43,120
Speaker 1: things that have similar masses, like dwarf planets and their moons. So,

759
00:35:43,200 --> 00:35:46,319
Speaker 1: for example, Pluto no longer a planet, but it's still

760
00:35:46,360 --> 00:35:50,360
Speaker 1: a dwarf planet. It's got a pretty big moon, Sharon,

761
00:35:50,960 --> 00:35:54,600
Speaker 1: and these two things are mutually tightly locked already. So

762
00:35:54,640 --> 00:35:56,560
Speaker 1: if you're like on Pluto and you look up, you

763
00:35:56,680 --> 00:35:59,520
Speaker 1: always see the same side of the Moon. And if

764
00:35:59,560 --> 00:36:02,239
Speaker 1: you're on Moon and you look up, you always see

765
00:36:02,280 --> 00:36:03,760
Speaker 1: the same side of Pluto.

766
00:36:04,000 --> 00:36:04,239
Speaker 4: Oh.

767
00:36:04,320 --> 00:36:06,040
Speaker 2: Interesting to how many moons does Pluto have.

768
00:36:06,320 --> 00:36:08,360
Speaker 1: Oh, Pluto's got a bunch of moons, but most of

769
00:36:08,360 --> 00:36:11,680
Speaker 1: them rotate chaotically. They're too small to have been tidly

770
00:36:11,719 --> 00:36:14,279
Speaker 1: locked so far. But it's sort of beautiful to see

771
00:36:14,280 --> 00:36:16,840
Speaker 1: these things like orbiting their center of mass and facing

772
00:36:16,880 --> 00:36:18,280
Speaker 1: each other. It's kind of like a dance.

773
00:36:18,640 --> 00:36:20,799
Speaker 2: Yeah, that's awesome. It's beautiful.

774
00:36:20,880 --> 00:36:23,040
Speaker 1: And that's not the only example of a dwarf planet.

775
00:36:23,080 --> 00:36:26,600
Speaker 1: There's another one out there, a trans Neptunian object called Eris,

776
00:36:26,600 --> 00:36:28,880
Speaker 1: which is also a dwarf planet, and it's got a

777
00:36:28,880 --> 00:36:32,160
Speaker 1: pretty big moon called Dyspnomia, which happens to be the

778
00:36:32,280 --> 00:36:36,759
Speaker 1: second largest dwarf planet moon after Pluto's moon, and these

779
00:36:36,760 --> 00:36:38,799
Speaker 1: two are also tidly locked with each other.

780
00:36:39,080 --> 00:36:42,000
Speaker 2: That sounds like it's a pretty common thing for dwarf

781
00:36:42,040 --> 00:36:44,239
Speaker 2: planets to have moons, that know, because how many dwarf

782
00:36:44,239 --> 00:36:45,000
Speaker 2: planets are there.

783
00:36:45,120 --> 00:36:47,040
Speaker 1: There's a lot of dwarf planets out there. That's one

784
00:36:47,120 --> 00:36:49,759
Speaker 1: reason why Pluto isn't really a planet anymore, because we

785
00:36:49,840 --> 00:36:52,120
Speaker 1: discovered there's kind of a lot of them out there.

786
00:36:52,160 --> 00:36:53,800
Speaker 1: And if we call Pluto a planet, we've got to

787
00:36:53,840 --> 00:36:56,000
Speaker 1: call them all planets, and then we're going to have

788
00:36:56,040 --> 00:36:58,120
Speaker 1: a lot of planet and so you know, astronomers have

789
00:36:58,200 --> 00:37:00,759
Speaker 1: big arguments about where to draw the line, but there's

790
00:37:00,760 --> 00:37:02,200
Speaker 1: a lot of dwarf planets.

791
00:37:01,800 --> 00:37:03,560
Speaker 2: Out there, right, and like, how are we going to

792
00:37:03,640 --> 00:37:05,920
Speaker 2: have naemonic if there's twenty of one or something like?

793
00:37:05,960 --> 00:37:08,279
Speaker 2: We just no way, no way, all right. So that's

794
00:37:08,360 --> 00:37:12,160
Speaker 2: our solar system. This sounds like a fundamental physics thing.

795
00:37:12,280 --> 00:37:14,760
Speaker 2: So I'm guessing that when we look at other solar systems,

796
00:37:14,800 --> 00:37:16,040
Speaker 2: they've got the same thing going on.

797
00:37:16,239 --> 00:37:19,360
Speaker 1: Yes, exactly. We expect that the same thing will happen

798
00:37:19,400 --> 00:37:23,239
Speaker 1: to planets around other stars and to moons around those planets,

799
00:37:23,840 --> 00:37:25,920
Speaker 1: and because of sort of the way that we can

800
00:37:25,960 --> 00:37:29,520
Speaker 1: discover those exoplanets. We expect a lot of the ones

801
00:37:29,560 --> 00:37:33,040
Speaker 1: we've seen so far have been tidly locked. Like the

802
00:37:33,040 --> 00:37:36,000
Speaker 1: way that we discover these planets is by seeing their

803
00:37:36,040 --> 00:37:39,040
Speaker 1: impact on their star. Either they pass in front of

804
00:37:39,080 --> 00:37:41,719
Speaker 1: their stars, so they give like a little mini planetary

805
00:37:41,760 --> 00:37:45,000
Speaker 1: eclipse which dims the star a little bit, or they

806
00:37:45,040 --> 00:37:47,760
Speaker 1: wiggle the star because of the gravity of the planet

807
00:37:47,800 --> 00:37:50,640
Speaker 1: pulling on the star. So in both cases they have

808
00:37:50,719 --> 00:37:52,920
Speaker 1: to be pretty close to the star for us to

809
00:37:52,960 --> 00:37:55,120
Speaker 1: see it, which means that of all the planets out

810
00:37:55,160 --> 00:37:57,960
Speaker 1: there in the galaxy orbiting their stars, we're best at

811
00:37:57,960 --> 00:38:00,520
Speaker 1: seeing the ones that are closest to their stars, which

812
00:38:00,600 --> 00:38:03,200
Speaker 1: also means we're best at seeing the ones that are

813
00:38:03,239 --> 00:38:07,120
Speaker 1: probably tidally locked. And so astronomers have done a bunch

814
00:38:07,120 --> 00:38:09,480
Speaker 1: of calculations to understand the orbits of these things and

815
00:38:09,520 --> 00:38:12,800
Speaker 1: the masses and predict their tidle locking, and they expect

816
00:38:12,840 --> 00:38:15,920
Speaker 1: that a lot of these planets are tidly locked, maybe

817
00:38:16,000 --> 00:38:18,560
Speaker 1: one to one, maybe like three to two the way

818
00:38:18,560 --> 00:38:21,720
Speaker 1: Mercury is, or maybe like five to two. It depends

819
00:38:21,760 --> 00:38:24,080
Speaker 1: a lot on the eccentricity of the orbit. Wh's the

820
00:38:24,080 --> 00:38:27,000
Speaker 1: sort of gravitationally most preferred arrangement.

821
00:38:27,200 --> 00:38:29,640
Speaker 2: Would it be fair to say that it's too far

822
00:38:29,800 --> 00:38:32,440
Speaker 2: away for us to have been able outside of our

823
00:38:32,480 --> 00:38:36,360
Speaker 2: solar system to see planets and their moons being tidally locked,

824
00:38:36,360 --> 00:38:37,719
Speaker 2: and so the only thing we've been able to look

825
00:38:37,719 --> 00:38:40,680
Speaker 2: at so far is tidal locking with suns and planets.

826
00:38:40,840 --> 00:38:44,200
Speaker 1: Yeah, that's exactly right. Exo moons is a brand new

827
00:38:44,320 --> 00:38:47,520
Speaker 1: area of study. People looking for these moons around exo

828
00:38:47,600 --> 00:38:50,719
Speaker 1: planets super exciting and in the next few years, as

829
00:38:50,760 --> 00:38:53,080
Speaker 1: we turn on more and more space telescopes, we're going

830
00:38:53,120 --> 00:38:56,760
Speaker 1: to get more information about these planets and their moons

831
00:38:56,920 --> 00:38:58,680
Speaker 1: and we can start to measure their spin and to

832
00:38:58,760 --> 00:39:01,480
Speaker 1: understand this and to figure out like whether these planets

833
00:39:01,520 --> 00:39:04,040
Speaker 1: out there a lot more of them are tidly locked

834
00:39:04,120 --> 00:39:06,440
Speaker 1: or a lot less. You know, a question we always

835
00:39:06,520 --> 00:39:10,680
Speaker 1: have is is our solar system weird or is it typical?

836
00:39:11,160 --> 00:39:13,600
Speaker 1: Like in most cases, is it just the first couple

837
00:39:13,640 --> 00:39:15,960
Speaker 1: of planets closest to the Sun that are tidally locked,

838
00:39:16,000 --> 00:39:18,239
Speaker 1: which would align with our understanding and tell us that

839
00:39:18,280 --> 00:39:21,240
Speaker 1: our solar systems not that weird, or maybe would be surprised,

840
00:39:21,280 --> 00:39:23,720
Speaker 1: and we'll discover Oh my gosh, all those solar systems

841
00:39:23,719 --> 00:39:26,240
Speaker 1: out there, they're all tidly locked. What's going on. Something

842
00:39:26,400 --> 00:39:29,319
Speaker 1: is different from what we expect. You never know when

843
00:39:29,360 --> 00:39:31,480
Speaker 1: you go out in the universe and ask these questions

844
00:39:31,480 --> 00:39:33,400
Speaker 1: and look for the first time, if you're just going

845
00:39:33,440 --> 00:39:36,000
Speaker 1: to see like more dust and rubbel or something really

846
00:39:36,000 --> 00:39:36,760
Speaker 1: really exciting.

847
00:39:36,960 --> 00:39:39,520
Speaker 2: The universe is good at providing job security in the

848
00:39:39,560 --> 00:39:40,719
Speaker 2: form of new questions.

849
00:39:40,800 --> 00:39:43,120
Speaker 1: And it's not just stars and planets we can study.

850
00:39:43,120 --> 00:39:47,120
Speaker 1: We can also look at pairs of stars. We're used

851
00:39:47,120 --> 00:39:50,040
Speaker 1: to thinking about stars as like individual and you have

852
00:39:50,080 --> 00:39:52,520
Speaker 1: a solar system with one star at its core and

853
00:39:52,560 --> 00:39:55,719
Speaker 1: a bunch of planets, But actually there's lots of binary

854
00:39:55,800 --> 00:39:58,680
Speaker 1: star systems out there. And the reason is that stars,

855
00:39:58,719 --> 00:40:01,000
Speaker 1: when they're formed, it's a big cloud of gas and

856
00:40:01,080 --> 00:40:04,480
Speaker 1: dust which collapses, and typically you get multiple stars from

857
00:40:04,520 --> 00:40:06,680
Speaker 1: a big cloud of gas and dust. You have like

858
00:40:06,760 --> 00:40:11,160
Speaker 1: little gravitational seeds that start this runaway gravitational effect, and

859
00:40:11,200 --> 00:40:12,799
Speaker 1: you don't just have one seed, you have a bunch

860
00:40:12,800 --> 00:40:15,319
Speaker 1: of them, so you get like an stellar nursery makes

861
00:40:15,520 --> 00:40:17,959
Speaker 1: lots and lots of stars. So we have a whole

862
00:40:17,960 --> 00:40:21,400
Speaker 1: podcast episode about binary star systems and even like trinary

863
00:40:21,480 --> 00:40:23,960
Speaker 1: star systems. But the point is that lots of stars

864
00:40:24,000 --> 00:40:27,239
Speaker 1: out there have brothers and sisters they were born with

865
00:40:27,360 --> 00:40:30,680
Speaker 1: like twins, and so they're pretty close to another star,

866
00:40:30,960 --> 00:40:33,440
Speaker 1: which means that you can have pairs of stars that

867
00:40:33,480 --> 00:40:35,359
Speaker 1: are tidly locked to each other.

868
00:40:35,680 --> 00:40:36,760
Speaker 2: That's awesome.

869
00:40:36,960 --> 00:40:39,160
Speaker 1: Or if you have a really big planet, you could

870
00:40:39,200 --> 00:40:41,479
Speaker 1: have a planet and a star that are tidly locked

871
00:40:41,520 --> 00:40:44,000
Speaker 1: to each other, so the planet is always seeing the

872
00:40:44,040 --> 00:40:47,280
Speaker 1: same side of the star. Right, that could be weird.

873
00:40:47,719 --> 00:40:49,720
Speaker 2: Yeah, but we haven't seen that yet, Right.

874
00:40:49,719 --> 00:40:51,680
Speaker 1: We have not seen that yet. There's a star out

875
00:40:51,680 --> 00:40:55,319
Speaker 1: there Tao Buddhists, which we suspect is tidly locked to

876
00:40:55,520 --> 00:40:58,040
Speaker 1: its planet, but we're not one hundred percent sure of that.

877
00:40:58,120 --> 00:40:59,960
Speaker 1: But you know, this kind of stuff makes a difference

878
00:41:00,120 --> 00:41:03,040
Speaker 1: because it really changes the experience of being on a planet.

879
00:41:03,320 --> 00:41:05,919
Speaker 1: Like if Earth was tidly locked to the sun, we'd

880
00:41:06,000 --> 00:41:08,160
Speaker 1: have half of the Earth at sunshine all day, and

881
00:41:08,280 --> 00:41:10,680
Speaker 1: half of the Earth would be the dark side of

882
00:41:10,680 --> 00:41:12,600
Speaker 1: the Earth. The far side of the Earth would be

883
00:41:12,640 --> 00:41:15,240
Speaker 1: the dark side, you know where Pink Floyd plays concerts

884
00:41:15,280 --> 00:41:18,400
Speaker 1: and Gary Larson draws his cartoons, And that would be

885
00:41:18,440 --> 00:41:22,000
Speaker 1: the very very cold side of the Earth, right dead side,

886
00:41:22,040 --> 00:41:24,520
Speaker 1: the oh, the dead side exactly. And then you'd have

887
00:41:24,640 --> 00:41:26,880
Speaker 1: this ring around the middle of the Earth that was

888
00:41:26,920 --> 00:41:29,359
Speaker 1: like right on the edge, you'd be like permanent sunrise,

889
00:41:30,040 --> 00:41:32,360
Speaker 1: and that might be the only place on the planet

890
00:41:32,440 --> 00:41:34,439
Speaker 1: you could live because one side would be too hot

891
00:41:34,480 --> 00:41:36,160
Speaker 1: and one side would be too cold. And then you'd

892
00:41:36,160 --> 00:41:39,520
Speaker 1: have this like goldilocks ring around the planet that might

893
00:41:39,600 --> 00:41:40,400
Speaker 1: be hospitable.

894
00:41:40,560 --> 00:41:42,560
Speaker 2: Location, location, location.

895
00:41:44,480 --> 00:41:46,759
Speaker 1: Exactly. And so if that's the case on some of

896
00:41:46,760 --> 00:41:49,799
Speaker 1: these exoplanets, that means it'd be a lot harder for

897
00:41:49,960 --> 00:41:52,560
Speaker 1: life to form. Either they'd have to evolve to survive

898
00:41:52,719 --> 00:41:56,239
Speaker 1: very hot conditions or very cold conditions, or there'd only

899
00:41:56,280 --> 00:41:58,600
Speaker 1: be a thin strip of their planet that they could

900
00:41:58,600 --> 00:42:00,560
Speaker 1: live on, and you know, then there wouldn't be seasons.

901
00:42:00,560 --> 00:42:02,239
Speaker 1: In the same way, it would make for a very

902
00:42:02,280 --> 00:42:03,759
Speaker 1: different kind of biology.

903
00:42:04,040 --> 00:42:07,120
Speaker 2: It would make it easy to study extremophiles, though, because

904
00:42:07,160 --> 00:42:10,080
Speaker 2: you know exactly where you needed to go, just you know,

905
00:42:10,120 --> 00:42:11,879
Speaker 2: the cold ones are over there and the hot ones

906
00:42:11,920 --> 00:42:13,600
Speaker 2: are over there. But there probably wouldn't be a lot

907
00:42:13,600 --> 00:42:15,120
Speaker 2: of funding for science in a world like that.

908
00:42:16,280 --> 00:42:18,800
Speaker 1: You never know, right, and we have all these expectations

909
00:42:18,800 --> 00:42:21,160
Speaker 1: for what life would be like on these planets, because

910
00:42:21,200 --> 00:42:23,840
Speaker 1: we imagine what our life would be like on those planets.

911
00:42:23,880 --> 00:42:26,160
Speaker 1: But of course, if you evolve on those planets, you'd

912
00:42:26,160 --> 00:42:28,080
Speaker 1: think that's the normal way to live, and they would

913
00:42:28,239 --> 00:42:31,279
Speaker 1: think it's super duper weird for like your planet to

914
00:42:31,320 --> 00:42:34,880
Speaker 1: spin and get constantly bathed in sunlight, or for you

915
00:42:34,920 --> 00:42:37,560
Speaker 1: to have no control over whether you're seeing the sun

916
00:42:37,680 --> 00:42:40,239
Speaker 1: or not. Because on tidly locked planets, right, you don't

917
00:42:40,239 --> 00:42:42,960
Speaker 1: want sun, you just move to the backside. You want sun,

918
00:42:43,000 --> 00:42:44,920
Speaker 1: you move to the front side, totally up to you,

919
00:42:45,160 --> 00:42:48,320
Speaker 1: whereas here we're like at the mercy of celestial objects,

920
00:42:48,520 --> 00:42:51,120
Speaker 1: spin rates to determine when we see sun and when

921
00:42:51,120 --> 00:42:51,520
Speaker 1: we don't.

922
00:42:51,719 --> 00:42:53,480
Speaker 2: Yeah, I guess you get used to what you grew

923
00:42:53,560 --> 00:42:56,440
Speaker 2: up with. It sure seems like it's nice to have

924
00:42:56,480 --> 00:42:58,000
Speaker 2: a more moderate in between.

925
00:42:58,360 --> 00:43:01,560
Speaker 1: It certainly does. But in the end, the universe prefers

926
00:43:01,680 --> 00:43:04,279
Speaker 1: tidal luck, and given enough time gravity, it's going to

927
00:43:04,360 --> 00:43:06,880
Speaker 1: do its business, make everything round and then make it

928
00:43:06,920 --> 00:43:09,520
Speaker 1: a little bit footballish, and it's going to tug on

929
00:43:09,600 --> 00:43:14,160
Speaker 1: those gravitational handles until everything is tidly locked, unless, of course,

930
00:43:14,239 --> 00:43:17,440
Speaker 1: your son explodes and eats you before it can even happen,

931
00:43:17,520 --> 00:43:20,120
Speaker 1: but it's sort of the gravitational destiny of every other

932
00:43:20,239 --> 00:43:20,920
Speaker 1: kind of object.

933
00:43:21,200 --> 00:43:24,640
Speaker 2: And there's the ending that'll keep from listening.

934
00:43:26,400 --> 00:43:30,799
Speaker 1: And hopefully inspire a lot of crazy music and silly cartoons. Yes,

935
00:43:31,560 --> 00:43:34,200
Speaker 1: all right, Thanks very much everybody for exploring the physics

936
00:43:34,239 --> 00:43:36,680
Speaker 1: of tidal locking with us. It turns out to play

937
00:43:36,680 --> 00:43:38,759
Speaker 1: a big role in what it's like to live on

938
00:43:38,760 --> 00:43:40,800
Speaker 1: our planet, what it's like to look up at disguise

939
00:43:40,920 --> 00:43:44,880
Speaker 1: and understand the universe or wonder at its mysteries, and

940
00:43:44,920 --> 00:43:47,280
Speaker 1: it will continue to play a big role in life

941
00:43:47,320 --> 00:43:47,880
Speaker 1: on Earth.

942
00:43:47,960 --> 00:43:48,280
Speaker 2: Huzza.

943
00:43:48,480 --> 00:43:58,880
Speaker 1: Thanks for listening. Tune in next time. Thanks for listening,

944
00:43:58,920 --> 00:44:01,600
Speaker 1: and remember that Daniel and Jorge Explain the Universe is

945
00:44:01,640 --> 00:44:06,239
Speaker 1: a production of iHeartRadio. For more podcasts from iHeartRadio, visit

946
00:44:06,320 --> 00:44:10,360
Speaker 1: the iHeartRadio app, Apple Podcasts, or wherever you listen to

947
00:44:10,440 --> 00:44:11,440
Speaker 1: your favorite shows.