1
00:00:07,800 --> 00:00:11,080
Speaker 1: The Moon really doesn't get enough love. Of all of

2
00:00:11,119 --> 00:00:13,880
Speaker 1: the features of the night sky. It's the only one

3
00:00:13,960 --> 00:00:17,760
Speaker 1: with real texture visible to the naked eye. Everything else

4
00:00:17,960 --> 00:00:21,680
Speaker 1: is either just a tiny distant point or an overwhelming

5
00:00:21,760 --> 00:00:24,799
Speaker 1: ball of fire. There's nothing else out there that you

6
00:00:24,840 --> 00:00:28,960
Speaker 1: can just sit and stare at and appreciate the feeling

7
00:00:29,120 --> 00:00:32,960
Speaker 1: of looking through a gulf in space. We are here

8
00:00:33,000 --> 00:00:36,440
Speaker 1: on a rock in space, and there's another whole rock

9
00:00:36,600 --> 00:00:40,560
Speaker 1: right over there, so far away yet so weirdly big,

10
00:00:40,640 --> 00:00:44,040
Speaker 1: that we can see it and see features on it.

11
00:00:44,040 --> 00:00:47,120
Speaker 1: It challenges the mind, forcing you to come to griffs

12
00:00:47,159 --> 00:00:51,279
Speaker 1: with our cosmic context of massive balls of rock spinning

13
00:00:51,320 --> 00:00:54,880
Speaker 1: through a dark ocean. And there's so much more that

14
00:00:54,960 --> 00:00:57,760
Speaker 1: moons do. Moons tell us about the history of the

15
00:00:57,800 --> 00:01:01,320
Speaker 1: Solar System and help reveal what's going on inside their planets.

16
00:01:01,560 --> 00:01:04,480
Speaker 1: They have volcanoes and weird colors and shoot jets of

17
00:01:04,520 --> 00:01:09,320
Speaker 1: water into space. They might even harbor life. Seeing Jupiter's

18
00:01:09,360 --> 00:01:13,080
Speaker 1: moons is what led Galileo to understand the structure of

19
00:01:13,080 --> 00:01:16,600
Speaker 1: our Solar system. And the thing that our moon has

20
00:01:16,680 --> 00:01:21,160
Speaker 1: misled us about is their number. Having one big, fat

21
00:01:21,200 --> 00:01:24,880
Speaker 1: moon is not normal planets, and our Solar system have

22
00:01:25,200 --> 00:01:29,960
Speaker 1: many moons, so many fabulous moons. So on this episode,

23
00:01:30,000 --> 00:01:33,520
Speaker 1: we're going to give moons the love they deserve. Welcome

24
00:01:33,640 --> 00:01:37,840
Speaker 1: to Daniel and Kelly's Extraordinary moon Malicious Universe.

25
00:01:51,080 --> 00:01:54,520
Speaker 2: Hello. I'm Kelly Waitersmith. I study parasites and space, and

26
00:01:54,680 --> 00:01:57,200
Speaker 2: I am not above jokes that involve mooning.

27
00:01:59,320 --> 00:02:03,000
Speaker 1: Hiel, I'm a particle physicist, and I can't tell you

28
00:02:03,040 --> 00:02:05,440
Speaker 1: how long it's been since I mooned somebody.

29
00:02:05,840 --> 00:02:10,360
Speaker 2: Oh, yes, that was a joy to hear about mooning

30
00:02:10,440 --> 00:02:12,239
Speaker 2: jokes when I was a kid. I don't remember actually

31
00:02:12,280 --> 00:02:14,040
Speaker 2: mooning anyone in my teens. I was a bit of

32
00:02:14,120 --> 00:02:18,400
Speaker 2: an insecure teen. But but ah, yes, I remember being

33
00:02:18,440 --> 00:02:19,040
Speaker 2: mooned as.

34
00:02:18,919 --> 00:02:22,480
Speaker 1: A teen and as an adult. Kelly, can I ask

35
00:02:22,560 --> 00:02:24,680
Speaker 1: you how long has it been since you mooned anybody?

36
00:02:24,919 --> 00:02:29,040
Speaker 2: I plead the fifth I married a man whose last

37
00:02:29,120 --> 00:02:31,720
Speaker 2: name is Wiener, and so my sense of humor has

38
00:02:31,919 --> 00:02:33,160
Speaker 2: become a bit more juvenile.

39
00:02:34,919 --> 00:02:37,040
Speaker 1: Fill in the gaps yourself, everybody, that's.

40
00:02:36,960 --> 00:02:39,919
Speaker 2: Right answer, Daniel. My question for you is, so today

41
00:02:39,919 --> 00:02:44,440
Speaker 2: we are talking about moons. Have you ever heard of

42
00:02:44,480 --> 00:02:49,280
Speaker 2: a convincing story of the moon influencing someone's behavior? Oh?

43
00:02:49,400 --> 00:02:51,920
Speaker 1: I mean, I can imagine the moon influencing the tides,

44
00:02:51,960 --> 00:02:54,320
Speaker 1: and the tides definitely influence people, m h.

45
00:02:54,880 --> 00:02:57,040
Speaker 2: But you don't buy the like, you know, more people

46
00:02:57,080 --> 00:02:58,800
Speaker 2: come into the er on a full moon.

47
00:02:59,360 --> 00:03:02,200
Speaker 1: People do all all sorts of weird stuff, and I

48
00:03:02,240 --> 00:03:05,240
Speaker 1: wouldn't be surprised if people acted weirder on a full

49
00:03:05,320 --> 00:03:08,120
Speaker 1: moon and there were more visits to the er. So

50
00:03:08,240 --> 00:03:09,919
Speaker 1: I'm gonna have to play the fifth on that one.

51
00:03:11,000 --> 00:03:13,800
Speaker 2: Yeah, I mean, I don't think I buy that people

52
00:03:13,840 --> 00:03:17,760
Speaker 2: are like more kooky on full moon nights unless they

53
00:03:17,760 --> 00:03:20,680
Speaker 2: have been convinced that they ought to be more like

54
00:03:20,840 --> 00:03:23,000
Speaker 2: risk taking on full moon nights and it's on their

55
00:03:23,080 --> 00:03:25,120
Speaker 2: mind than I can imagine like they sort of have

56
00:03:25,160 --> 00:03:28,040
Speaker 2: psyched themselves out. But I do like, if I get

57
00:03:28,520 --> 00:03:31,240
Speaker 2: up early in the morning and it's brighter because of

58
00:03:31,240 --> 00:03:33,760
Speaker 2: a full moon, I'll be more likely to like go

59
00:03:33,919 --> 00:03:37,440
Speaker 2: jogging or something. And so I can imagine maybe people

60
00:03:38,280 --> 00:03:41,160
Speaker 2: going out and doing more stuff outside during a full

61
00:03:41,160 --> 00:03:44,200
Speaker 2: moon and maybe being more likely to like accidentally get

62
00:03:44,240 --> 00:03:46,360
Speaker 2: hit by a car or something like that. And of

63
00:03:46,360 --> 00:03:49,720
Speaker 2: course we were talking about how some organisms are influenced

64
00:03:49,720 --> 00:03:52,320
Speaker 2: by the tide and so their's circadian rhythms are influenced

65
00:03:52,320 --> 00:03:54,800
Speaker 2: by the tide, so their behaviors are influenced by the tide.

66
00:03:55,000 --> 00:03:57,440
Speaker 2: But yeah, I don't think I buy that animals or

67
00:03:57,480 --> 00:04:01,320
Speaker 2: people are more likely to be doing kooky crazy stuff

68
00:04:01,880 --> 00:04:04,560
Speaker 2: because it's a full moon or anything like that.

69
00:04:04,720 --> 00:04:07,920
Speaker 1: But I don't know. People are weird, and I think

70
00:04:07,920 --> 00:04:10,640
Speaker 1: if you work in an er, you see the weirdest

71
00:04:10,640 --> 00:04:13,080
Speaker 1: side of people. I remember Katrina worked at a hospital

72
00:04:13,160 --> 00:04:17,000
Speaker 1: in Geneva, and near the entrance they had a huge

73
00:04:17,000 --> 00:04:19,960
Speaker 1: display of the weirdest stuff they had pulled out of

74
00:04:20,000 --> 00:04:23,839
Speaker 1: people's throats and other holes. Oh no, and boy was

75
00:04:23,839 --> 00:04:25,280
Speaker 1: there some weird stuff there.

76
00:04:25,520 --> 00:04:29,680
Speaker 2: Oh. I did once for a research project look for

77
00:04:29,800 --> 00:04:34,080
Speaker 2: papers describing things that had been pulled from orifices. And

78
00:04:34,839 --> 00:04:39,279
Speaker 2: we are an inventive species, and if it turns out

79
00:04:39,400 --> 00:04:42,599
Speaker 2: that our inventive behaviors are tied to full moons, then

80
00:04:42,640 --> 00:04:45,400
Speaker 2: we might be happy that we have only one moon

81
00:04:45,880 --> 00:04:47,440
Speaker 2: and not many moons.

82
00:04:48,400 --> 00:04:51,360
Speaker 1: And the moon figures so prominently in the sky and

83
00:04:51,440 --> 00:04:55,200
Speaker 1: in our literature and in our imaginations that it's easy

84
00:04:55,200 --> 00:04:57,160
Speaker 1: to imagine that aliens would look up to their sky

85
00:04:57,240 --> 00:04:59,559
Speaker 1: and see the same thing. Or if you're a science

86
00:04:59,560 --> 00:05:03,000
Speaker 1: fiction off third to imagine alien seeing a radically different sky,

87
00:05:03,600 --> 00:05:07,560
Speaker 1: many moons, or something similarly weird. And there are lots

88
00:05:07,560 --> 00:05:10,560
Speaker 1: of examples in science fiction of multiple suns or multiple

89
00:05:10,600 --> 00:05:14,960
Speaker 1: moons or other variations on our experience, but you don't

90
00:05:14,960 --> 00:05:17,600
Speaker 1: actually have to go that far visiting another solar system

91
00:05:17,920 --> 00:05:20,640
Speaker 1: to see examples of multiple moons.

92
00:05:21,000 --> 00:05:23,159
Speaker 2: And if I can just plug my friend's book for

93
00:05:23,160 --> 00:05:25,840
Speaker 2: a second, Under Alien Skies by Phil Plait is an

94
00:05:25,839 --> 00:05:29,159
Speaker 2: amazing book describing what might be like to visit alien

95
00:05:29,200 --> 00:05:32,240
Speaker 2: planets and look at their skies. And Phil was a

96
00:05:32,240 --> 00:05:34,320
Speaker 2: guest on our show early on when you and I

97
00:05:34,360 --> 00:05:35,920
Speaker 2: started podcasting together.

98
00:05:36,120 --> 00:05:39,560
Speaker 1: That's right, and everything he writes is insightful, well informed,

99
00:05:39,720 --> 00:05:41,599
Speaker 1: and fun, so go check it out.

100
00:05:41,720 --> 00:05:46,719
Speaker 2: Yes, all right, so you asked our extraordinaries which planet

101
00:05:46,880 --> 00:05:48,359
Speaker 2: has the most moons?

102
00:05:48,960 --> 00:05:51,120
Speaker 1: That's right, And if you would like to contribute for

103
00:05:51,160 --> 00:05:54,480
Speaker 1: this segment of the show in future episodes, please don't

104
00:05:54,480 --> 00:05:56,520
Speaker 1: be shy. We would love to add your voice to

105
00:05:56,560 --> 00:05:59,000
Speaker 1: the chorus. In the meantime, think about it for yourself

106
00:05:59,040 --> 00:06:01,680
Speaker 1: for a moment. Which planet in our solar system do

107
00:06:01,720 --> 00:06:05,560
Speaker 1: you think has the most moons? Here's what the extraordinaries

108
00:06:05,839 --> 00:06:06,640
Speaker 1: had to say.

109
00:06:06,880 --> 00:06:10,440
Speaker 3: And believe it's Jupiter. That has the most moons. I

110
00:06:10,480 --> 00:06:14,239
Speaker 3: think they just discovered a couple more, But technically really

111
00:06:14,279 --> 00:06:18,159
Speaker 3: depends on what you define as moon, because rings are

112
00:06:18,200 --> 00:06:21,920
Speaker 3: just particles orbiting the planet as well. In our Solar system,

113
00:06:22,000 --> 00:06:24,159
Speaker 3: the planet with the most moons is probably Saturn.

114
00:06:24,400 --> 00:06:26,680
Speaker 1: Outside of the Solar System, I have no clue.

115
00:06:26,839 --> 00:06:30,080
Speaker 3: I would say Jupiter because of how big it is,

116
00:06:30,880 --> 00:06:33,440
Speaker 3: but then it might have pulled some moons into it,

117
00:06:33,520 --> 00:06:35,720
Speaker 3: So maybe Saturn has the most because it sits in

118
00:06:35,760 --> 00:06:36,480
Speaker 3: a sweet spot.

119
00:06:36,920 --> 00:06:41,800
Speaker 1: What do you think, glenn on? Going straight for Jupiter? Why?

120
00:06:42,000 --> 00:06:45,080
Speaker 1: Because it has the most moons? All right?

121
00:06:45,720 --> 00:06:48,919
Speaker 3: My initial thought would be Saturn or Jupiter, but I

122
00:06:48,920 --> 00:06:52,000
Speaker 3: have been reading recent news reports about many new discoveries

123
00:06:52,000 --> 00:06:54,400
Speaker 3: of moons around Jupiter, so I'm going to go with Jupiter.

124
00:06:54,600 --> 00:06:58,200
Speaker 1: All right, So most votes for Jupiter. Kelly. If you

125
00:06:58,200 --> 00:07:00,000
Speaker 1: hadn't read the outline, what would you have done?

126
00:07:00,000 --> 00:07:02,240
Speaker 2: Cod Ah, I love that you think that I read

127
00:07:02,240 --> 00:07:04,040
Speaker 2: the outline.

128
00:07:03,920 --> 00:07:06,560
Speaker 1: Giving you the benefit of the doubt here just in case.

129
00:07:06,760 --> 00:07:08,640
Speaker 2: No, I'm kidding. I did read the outline, so I

130
00:07:08,640 --> 00:07:11,840
Speaker 2: would have guessed Saturn or Jupiter, or I would have

131
00:07:11,880 --> 00:07:15,640
Speaker 2: guessed that because this is a dKu episode, maybe the

132
00:07:15,680 --> 00:07:20,720
Speaker 2: answer is we don't know, because maybe maybe it's hard

133
00:07:20,720 --> 00:07:23,480
Speaker 2: to count all the moons and we aren't sure if

134
00:07:23,520 --> 00:07:25,200
Speaker 2: Saturn or Jupiter is the winner.

135
00:07:25,320 --> 00:07:30,360
Speaker 1: Yet that's probably the right answer. Actually, Also it depends

136
00:07:30,400 --> 00:07:33,320
Speaker 1: on what you mean by moon, the definition, which is

137
00:07:33,320 --> 00:07:36,520
Speaker 1: always evolving as we discover more stuff out there in

138
00:07:36,560 --> 00:07:39,680
Speaker 1: the Solar system, because though humans like to make tidy

139
00:07:39,760 --> 00:07:42,440
Speaker 1: categories for the things that are orbiting the Sun, in

140
00:07:42,520 --> 00:07:45,520
Speaker 1: reality the universe is chaotic and there's just like a

141
00:07:45,680 --> 00:07:49,720
Speaker 1: huge smooth spectrum of stuff from tiny little dust grains

142
00:07:49,760 --> 00:07:53,320
Speaker 1: all the way up to Jupiter and basically everything in between.

143
00:07:53,640 --> 00:07:55,520
Speaker 1: And if you try to put everything in boxes and

144
00:07:55,520 --> 00:07:58,080
Speaker 1: make artificial dotted lines to separate it, you'll find a

145
00:07:58,120 --> 00:08:01,200
Speaker 1: bunch of stuff in fuzzy category and you'll argue about

146
00:08:01,200 --> 00:08:03,480
Speaker 1: whether it's a moon or whether it's not a moon,

147
00:08:03,800 --> 00:08:05,520
Speaker 1: and that will probably change the answer.

148
00:08:05,800 --> 00:08:08,200
Speaker 2: Well, at least that's a bit more satisfying than like

149
00:08:08,280 --> 00:08:10,600
Speaker 2: our discussion on the ort cloud, where you're like, actually,

150
00:08:10,640 --> 00:08:13,000
Speaker 2: we're not even really sure there's an ork cloud, and

151
00:08:13,040 --> 00:08:14,520
Speaker 2: so you know, I was a little worried you we

152
00:08:14,520 --> 00:08:16,520
Speaker 2: were going to be like, actually, we're not even sure

153
00:08:16,560 --> 00:08:20,120
Speaker 2: that there's moons that could be an optical illusion. But anyway, Okay,

154
00:08:20,120 --> 00:08:22,840
Speaker 2: we're sure that there's moons. We're not quite sure where

155
00:08:22,840 --> 00:08:26,200
Speaker 2: the cutoff should be, but we've arbitrarily said it somewhere.

156
00:08:26,400 --> 00:08:30,240
Speaker 1: Yeah, exactly. So first let's clarify what we mean by

157
00:08:30,320 --> 00:08:33,360
Speaker 1: a moon. And this has a fascinating history, even just

158
00:08:33,400 --> 00:08:37,959
Speaker 1: the word is fairly recent and modern. Astronomically, the category

159
00:08:38,000 --> 00:08:41,880
Speaker 1: officially is natural satellite, and we use the word moon

160
00:08:42,120 --> 00:08:46,880
Speaker 1: sort of colloquially after the moon of Earth. Historically, people

161
00:08:46,920 --> 00:08:51,520
Speaker 1: called our moon a planet, like until Copernicus in fifteen hundred,

162
00:08:51,760 --> 00:08:54,440
Speaker 1: the term planet was basically used to describe like things

163
00:08:54,480 --> 00:08:57,280
Speaker 1: that move in the sky, which we assume to move

164
00:08:57,360 --> 00:08:59,760
Speaker 1: around the Earth, and the moon was just like another thing,

165
00:09:00,200 --> 00:09:02,440
Speaker 1: like the other planets, and like the Sun that people

166
00:09:02,520 --> 00:09:07,240
Speaker 1: assumed moved around the Earth. Then, of course Galileo saw

167
00:09:07,280 --> 00:09:10,880
Speaker 1: the moons of Jupiter and thought, ooh, the planets themselves

168
00:09:10,960 --> 00:09:13,520
Speaker 1: are like mini systems, and so you can have this

169
00:09:13,640 --> 00:09:17,560
Speaker 1: hierarchical structure, and so it's not required for everything to

170
00:09:17,840 --> 00:09:21,280
Speaker 1: orbit one thing or to orbit the Earth, and so

171
00:09:21,360 --> 00:09:24,000
Speaker 1: that gives way to a more nuanced structure of the

172
00:09:24,000 --> 00:09:26,200
Speaker 1: Solar System. And now you have to have different words

173
00:09:26,280 --> 00:09:29,600
Speaker 1: to define these things that are not directly orbiting the sun,

174
00:09:29,720 --> 00:09:32,160
Speaker 1: but are orbiting something that is orbiting the sun.

175
00:09:32,320 --> 00:09:35,319
Speaker 2: Okay, now, hold on, So recently you asked me what

176
00:09:35,440 --> 00:09:38,360
Speaker 2: killyfish means, and then you ask me what hymenopterin means.

177
00:09:39,040 --> 00:09:41,679
Speaker 1: Oh no, are we about to get some linguistic revenge?

178
00:09:42,280 --> 00:09:44,880
Speaker 2: Gosh? I hope so, because usually when I'm like, oh,

179
00:09:44,880 --> 00:09:48,440
Speaker 2: I'm about to get Daniel, You're like, oh, because Daniel

180
00:09:48,480 --> 00:09:50,320
Speaker 2: just knows. But I see you're about to hit your keyboard.

181
00:09:50,640 --> 00:09:53,360
Speaker 2: Does the word moon mean something? Did they take that

182
00:09:53,400 --> 00:09:56,360
Speaker 2: from something else? Yes?

183
00:09:57,160 --> 00:10:01,600
Speaker 1: Yes, so you know, the Latin name for the moon

184
00:10:01,880 --> 00:10:05,080
Speaker 1: is Luna. But the word moon itself actually comes from

185
00:10:05,080 --> 00:10:08,600
Speaker 1: the Old English word, which comes from a Germanic word,

186
00:10:08,960 --> 00:10:12,480
Speaker 1: which comes from a Proto Indo European word which might

187
00:10:12,520 --> 00:10:15,800
Speaker 1: be related to the measurement of time. And so yes,

188
00:10:15,880 --> 00:10:19,800
Speaker 1: the moon has this like ancient historical meaning connected with,

189
00:10:19,960 --> 00:10:22,440
Speaker 1: you know, the passage of time. And that's super fun

190
00:10:22,480 --> 00:10:24,560
Speaker 1: because we know that, like looking at patterns in the

191
00:10:24,600 --> 00:10:27,439
Speaker 1: sky is how a lot of ancient peoples first developed

192
00:10:27,480 --> 00:10:30,960
Speaker 1: like astronomy and mathematics and you know, trying to predict

193
00:10:31,000 --> 00:10:33,200
Speaker 1: the future. So it's like a deep rabbit hole all

194
00:10:33,240 --> 00:10:34,960
Speaker 1: the way to the origins of astronomy.

195
00:10:35,320 --> 00:10:38,440
Speaker 2: Okay, I mean that's it's not quite as much fun

196
00:10:38,440 --> 00:10:40,640
Speaker 2: as I was hoping, but like sort of fun. All right.

197
00:10:40,679 --> 00:10:42,640
Speaker 1: So you're hoping it was related to butts, weren't you?

198
00:10:42,720 --> 00:10:46,079
Speaker 2: I mean probably, like, yes, the act of dropping one's

199
00:10:46,120 --> 00:10:50,080
Speaker 2: pants is what I was hoping for, but maybe this

200
00:10:50,160 --> 00:10:53,120
Speaker 2: is I got to keep this kid friendly. Also, teeny

201
00:10:53,160 --> 00:10:56,000
Speaker 2: pet peeve of mine. I feel like, whenever you're referring

202
00:10:56,040 --> 00:10:58,240
Speaker 2: to the moon of Earth, you need to be careful

203
00:10:58,280 --> 00:11:01,280
Speaker 2: to capitalize it because we're referring to it's a specific moon.

204
00:11:01,400 --> 00:11:04,720
Speaker 2: Then the other moons can get a lower case because

205
00:11:04,720 --> 00:11:07,679
Speaker 2: we're referring to moons in general exactly.

206
00:11:08,160 --> 00:11:09,880
Speaker 1: And you know, for a long time, we refer to

207
00:11:09,960 --> 00:11:12,880
Speaker 1: all of these things as just satellites, so instead of

208
00:11:12,880 --> 00:11:15,559
Speaker 1: calling them moons, you would say the satellites of Jupiter.

209
00:11:16,200 --> 00:11:19,720
Speaker 1: Then with Sputnak and the advent of artificial satellites, you know,

210
00:11:19,920 --> 00:11:22,960
Speaker 1: half a century ago it became very awkward to constantly

211
00:11:22,960 --> 00:11:27,440
Speaker 1: say artificial satellite, natural satellite, artificial satellite. And you know,

212
00:11:27,520 --> 00:11:30,800
Speaker 1: English is constantly smoothing and shortening things, and so people

213
00:11:30,840 --> 00:11:34,880
Speaker 1: just started referring to artificial satellites as satellites, and then

214
00:11:35,040 --> 00:11:38,720
Speaker 1: instead of referring to natural satellites, they just called everything moons,

215
00:11:39,240 --> 00:11:44,000
Speaker 1: sort of colloquially after our moon. So technically, astronomically we

216
00:11:44,080 --> 00:11:47,640
Speaker 1: have natural satellites and artificial satellites, but more practically we

217
00:11:47,720 --> 00:11:51,320
Speaker 1: have satellites, which mean artificial satellites which are not moons

218
00:11:51,480 --> 00:11:55,000
Speaker 1: or natural satellites, and then natural satellites that we call moons.

219
00:11:55,280 --> 00:11:57,559
Speaker 2: And I think the word sputnik is just the Russian

220
00:11:57,559 --> 00:11:59,040
Speaker 2: word for satellite.

221
00:11:59,200 --> 00:12:04,079
Speaker 1: Yeah. And then aside from the linguistic fuzziness, there is

222
00:12:04,200 --> 00:12:07,560
Speaker 1: also this question of like, well, what makes something a moon?

223
00:12:07,640 --> 00:12:09,360
Speaker 1: Like it's pretty clear if you're looking at the Earth

224
00:12:09,360 --> 00:12:11,600
Speaker 1: and the Moon, the Earth is bigger, and so you

225
00:12:11,640 --> 00:12:14,120
Speaker 1: would say that the moon is a moon and the

226
00:12:14,200 --> 00:12:17,240
Speaker 1: Earth is a satellite of the Sun. But physically speaking,

227
00:12:17,559 --> 00:12:19,920
Speaker 1: the Earth and the Moon are orbiting each other, right,

228
00:12:20,000 --> 00:12:22,360
Speaker 1: and there's a center of mass of the Earth Moon system,

229
00:12:22,640 --> 00:12:25,280
Speaker 1: and that is what's orbiting the Sun. And so it's

230
00:12:25,280 --> 00:12:27,800
Speaker 1: a little bit arbitrary to say, Okay, this one's a

231
00:12:27,800 --> 00:12:30,760
Speaker 1: moon and this one's a planet. You can imagine, for example,

232
00:12:30,800 --> 00:12:32,760
Speaker 1: a scenario where you have two objects of the same

233
00:12:32,800 --> 00:12:37,000
Speaker 1: mass orbiting each other, like a binary dwarf planet system,

234
00:12:37,559 --> 00:12:40,320
Speaker 1: which is the moon, which is a planet, right, you

235
00:12:40,400 --> 00:12:43,920
Speaker 1: need some way of categorizing it, and so in our

236
00:12:44,000 --> 00:12:47,360
Speaker 1: Solar system, typically if the center of mass of the

237
00:12:47,440 --> 00:12:51,000
Speaker 1: system is within the surface of one of the objects,

238
00:12:51,800 --> 00:12:54,680
Speaker 1: so that's like, you know, where is the average bit,

239
00:12:55,080 --> 00:12:57,760
Speaker 1: The average bit is under the surface, like between the

240
00:12:57,800 --> 00:12:59,559
Speaker 1: Earth and the Moon. The center of mass of the

241
00:12:59,600 --> 00:13:03,320
Speaker 1: Earth Moon system is within the volume of the Earth.

242
00:13:03,480 --> 00:13:06,800
Speaker 1: Then you say that's the planet and anything else outside

243
00:13:06,840 --> 00:13:09,839
Speaker 1: of that is a moon. It's a little bit arbitrary,

244
00:13:10,080 --> 00:13:14,360
Speaker 1: but it's helpful to settling debates among astronomers, which you know,

245
00:13:15,000 --> 00:13:16,640
Speaker 1: you have to have a reason for those guys to

246
00:13:16,880 --> 00:13:20,360
Speaker 1: stop drinking and go to sleep. And there's the other

247
00:13:20,440 --> 00:13:23,040
Speaker 1: side of it, which is like, well, what's the smallest

248
00:13:23,120 --> 00:13:27,600
Speaker 1: possible moon? Right? Like is every dust grain that's orbiting

249
00:13:27,640 --> 00:13:31,280
Speaker 1: the Earth a natural satellite if it formed naturally? Like,

250
00:13:31,400 --> 00:13:34,679
Speaker 1: is there a lowest cutoff? Is every proton that's in

251
00:13:34,840 --> 00:13:39,000
Speaker 1: orbit around the Earth a satellite? Technically according to the

252
00:13:39,040 --> 00:13:43,320
Speaker 1: definition of natural satellite, yes, those are natural satellites. You

253
00:13:43,360 --> 00:13:46,360
Speaker 1: don't count them as moons of Earth. And later we'll

254
00:13:46,360 --> 00:13:48,720
Speaker 1: talk about how the Earth actually does have a weird

255
00:13:48,880 --> 00:13:51,960
Speaker 1: second body that's kind of orbiting it but not really

256
00:13:51,960 --> 00:13:54,680
Speaker 1: that you could argue is kind of like a second

257
00:13:54,720 --> 00:13:58,439
Speaker 1: moon of the Earth. Anyway, the point is it depends

258
00:13:58,840 --> 00:14:02,360
Speaker 1: on the definition. And so, yeah, Kelly, really nobody knows.

259
00:14:02,679 --> 00:14:06,280
Speaker 2: Yes, yes, I knew, I was right. That's great, But

260
00:14:07,480 --> 00:14:09,720
Speaker 2: it does seem like, you know, you talk to ninety

261
00:14:09,800 --> 00:14:12,440
Speaker 2: nine point nine nine percent of the people on the planet,

262
00:14:12,480 --> 00:14:16,199
Speaker 2: they'd say that Earth has one moon, and is that

263
00:14:16,360 --> 00:14:18,240
Speaker 2: just because that's what we were told as kids and

264
00:14:18,240 --> 00:14:20,320
Speaker 2: it's stuck. But if you talk to an astronomer, they'd

265
00:14:20,320 --> 00:14:24,360
Speaker 2: be like, maybe we have a billion, or like, is

266
00:14:24,400 --> 00:14:27,920
Speaker 2: there essentially a definition that we all agree to for

267
00:14:28,040 --> 00:14:29,080
Speaker 2: convenience sake?

268
00:14:29,600 --> 00:14:32,920
Speaker 1: There is really no lower limit. But we call these

269
00:14:32,960 --> 00:14:36,120
Speaker 1: things moons because they're interesting. They reveal the structure of

270
00:14:36,160 --> 00:14:40,320
Speaker 1: the Solar System. They affect planets because of their tidal forces,

271
00:14:40,760 --> 00:14:43,800
Speaker 1: and tiny little dust grains don't do that as much,

272
00:14:43,840 --> 00:14:46,080
Speaker 1: and so they really are sort of a different kind

273
00:14:46,120 --> 00:14:48,720
Speaker 1: of thing. Even if it is an arbitrary dotted line

274
00:14:48,720 --> 00:14:51,360
Speaker 1: that we draw, and there really isn't a place to

275
00:14:51,360 --> 00:14:54,040
Speaker 1: put it. It doesn't make sense to put an individual

276
00:14:54,040 --> 00:14:56,680
Speaker 1: proton in the same category as the moon of Earth,

277
00:14:57,040 --> 00:15:00,480
Speaker 1: just because they both orbit the Earth, and so is

278
00:15:00,520 --> 00:15:03,800
Speaker 1: a qualitative difference, even if there isn't a crisp line

279
00:15:03,840 --> 00:15:05,720
Speaker 1: that we can draw. And so, no, I don't think

280
00:15:05,720 --> 00:15:08,240
Speaker 1: any astronomer is going to be like, actually, there are

281
00:15:08,240 --> 00:15:12,000
Speaker 1: many moons of Earth, but you know, probably maybe there

282
00:15:12,040 --> 00:15:13,080
Speaker 1: is one out there somewhere.

283
00:15:13,480 --> 00:15:15,480
Speaker 2: Is that what you think astronomers sound like? Because I

284
00:15:15,480 --> 00:15:17,600
Speaker 2: think you got to watch it. There might be some

285
00:15:17,640 --> 00:15:19,880
Speaker 2: astronomers that listen to this show and their feelings might

286
00:15:19,920 --> 00:15:20,520
Speaker 2: get hurt.

287
00:15:20,840 --> 00:15:24,480
Speaker 1: No, I think most astronomers sound like they're really fit.

288
00:15:24,840 --> 00:15:27,360
Speaker 1: They're very suave, but just the annoying ones sound like that.

289
00:15:27,520 --> 00:15:29,800
Speaker 2: Got it? Okay, So you said we have like this

290
00:15:29,960 --> 00:15:37,000
Speaker 2: arbitrary definition. Does this arbitrary definition have some features or

291
00:15:37,080 --> 00:15:39,720
Speaker 2: is it just like, is it always a gut feeling

292
00:15:39,960 --> 00:15:44,120
Speaker 2: or do we have some criteria even if it was

293
00:15:44,240 --> 00:15:45,880
Speaker 2: happened upon somewhat arbitrarily.

294
00:15:46,440 --> 00:15:51,400
Speaker 1: So, typically planets have something like ten thousand times the

295
00:15:51,440 --> 00:15:53,840
Speaker 1: mass of their natural satellite. That's what we tend to

296
00:15:53,840 --> 00:15:56,320
Speaker 1: see in the Solar System. But you know there are

297
00:15:56,360 --> 00:15:59,200
Speaker 1: already exceptions to that, Like the moon is one eightieth

298
00:15:59,240 --> 00:16:02,520
Speaker 1: of the Earth, Pluto has a moon that's one eighth

299
00:16:03,000 --> 00:16:05,880
Speaker 1: of its mass, right, and so like you can make

300
00:16:05,880 --> 00:16:09,160
Speaker 1: these broad categories. Almost all the moons in our Solar

301
00:16:09,200 --> 00:16:13,160
Speaker 1: system have a mass that's less than ten thousands of

302
00:16:13,200 --> 00:16:16,640
Speaker 1: the planetary mass. But there are already major exceptions.

303
00:16:17,600 --> 00:16:19,760
Speaker 2: Well, let's take a break. When we come back, we'll

304
00:16:19,760 --> 00:16:22,320
Speaker 2: talk about why we have moons. And if there are

305
00:16:22,360 --> 00:16:24,960
Speaker 2: any kids hanging out with you while you're listening to

306
00:16:25,000 --> 00:16:28,280
Speaker 2: this episode, kids, don't get any ideas. No mooning your

307
00:16:28,320 --> 00:16:31,400
Speaker 2: parents during the commercial break. When we get back, why

308
00:16:31,440 --> 00:16:54,880
Speaker 2: do we have moons? And we're back, So, Daniel, we

309
00:16:54,920 --> 00:16:57,880
Speaker 2: talked about how moons are defined, but why do we

310
00:16:57,920 --> 00:17:00,320
Speaker 2: have moons in the first place, and why did the Earth,

311
00:17:00,480 --> 00:17:04,600
Speaker 2: clearly the greatest planet in the Solar System, only get one.

312
00:17:05,160 --> 00:17:07,719
Speaker 1: Yeah, this is the most interesting thing about moons, in

313
00:17:07,720 --> 00:17:10,879
Speaker 1: my opinion, is that they reveal something about the history

314
00:17:10,920 --> 00:17:13,440
Speaker 1: of the Solar System. If you read about the Solar

315
00:17:13,440 --> 00:17:15,080
Speaker 1: System and look out at the sky, you get the

316
00:17:15,080 --> 00:17:18,760
Speaker 1: impression that it's this sort of calm parade. There's like

317
00:17:18,920 --> 00:17:22,040
Speaker 1: slow moving truds through space that's been going this way

318
00:17:22,080 --> 00:17:23,520
Speaker 1: for a long time and going to be going this

319
00:17:23,560 --> 00:17:26,919
Speaker 1: way forever. But that's only because we're used to living

320
00:17:27,160 --> 00:17:31,520
Speaker 1: at a sort of human timescale seconds, minutes, even centuries,

321
00:17:32,080 --> 00:17:34,760
Speaker 1: and in those timescales, yeah, not much really happens in

322
00:17:34,800 --> 00:17:37,679
Speaker 1: the Solar System. But the Solar System is very old.

323
00:17:37,760 --> 00:17:40,600
Speaker 1: It's four and a half billion years old, and its

324
00:17:40,720 --> 00:17:45,400
Speaker 1: history is filled with chaos. All sorts of crazy cosmic

325
00:17:45,440 --> 00:17:49,280
Speaker 1: cataclysms have occurred in our Solar System, from planets moving

326
00:17:49,359 --> 00:17:52,040
Speaker 1: in and out and switching orbits and losing planets. And

327
00:17:52,200 --> 00:17:54,960
Speaker 1: moons are a great way to understand this history because

328
00:17:55,000 --> 00:17:58,040
Speaker 1: they are in effect records of this history. And if

329
00:17:58,080 --> 00:18:00,480
Speaker 1: you understand it why a planet has a moon, you

330
00:18:00,480 --> 00:18:04,159
Speaker 1: can understand something about what happened to that planet. So

331
00:18:04,200 --> 00:18:08,040
Speaker 1: there's basically three different ways that planets can get moons,

332
00:18:08,400 --> 00:18:10,479
Speaker 1: from the least interesting all the way up to the

333
00:18:10,520 --> 00:18:11,600
Speaker 1: most exciting.

334
00:18:12,000 --> 00:18:14,840
Speaker 2: Well, I bet we are all super excited for you

335
00:18:14,920 --> 00:18:17,119
Speaker 2: to start with the least interesting. Explanation?

336
00:18:18,040 --> 00:18:20,320
Speaker 1: Was that a great lead in, right, lead into that

337
00:18:22,000 --> 00:18:26,840
Speaker 1: ready to get bored here, I'm in, Well, you don't

338
00:18:26,880 --> 00:18:29,320
Speaker 1: want to drop people with the most exciting one, and

339
00:18:29,359 --> 00:18:31,000
Speaker 1: then you know they're sort of spent and like, I

340
00:18:31,000 --> 00:18:32,320
Speaker 1: don't want to listen to the rest of this. You

341
00:18:32,400 --> 00:18:33,600
Speaker 1: got to build up to it, don't you.

342
00:18:33,680 --> 00:18:35,200
Speaker 2: But you don't even have to tell them there's a

343
00:18:35,320 --> 00:18:36,480
Speaker 2: least interesting option.

344
00:18:37,680 --> 00:18:40,680
Speaker 1: Great, all right, Well, the least interesting is already very

345
00:18:40,720 --> 00:18:45,400
Speaker 1: exciting because it tells you about the formation of the planet.

346
00:18:45,480 --> 00:18:48,720
Speaker 1: So sometimes moons form at the same time as the

347
00:18:48,720 --> 00:18:51,080
Speaker 1: planet in the same way that, like the structure of

348
00:18:51,119 --> 00:18:54,160
Speaker 1: our Solar System, didn't just make a sun, but also

349
00:18:54,200 --> 00:18:57,200
Speaker 1: made a bunch of planets. As those planets are forming,

350
00:18:57,400 --> 00:18:59,439
Speaker 1: they don't just make a planet, they also make their

351
00:18:59,480 --> 00:19:00,720
Speaker 1: own little.

352
00:19:00,359 --> 00:19:04,159
Speaker 2: Orbiting guys and gals space gals.

353
00:19:04,200 --> 00:19:07,080
Speaker 1: I like that. So why does the Solar System have

354
00:19:07,160 --> 00:19:09,960
Speaker 1: this kind of structure? Well, remember that the Solar System

355
00:19:10,080 --> 00:19:13,679
Speaker 1: formed from a central blob that collapse gravitationally. You have

356
00:19:13,760 --> 00:19:17,560
Speaker 1: like a seed somewhere where gravity started this runaway effect.

357
00:19:17,880 --> 00:19:19,760
Speaker 1: It got denser, so it had more gravity, so it

358
00:19:19,760 --> 00:19:21,399
Speaker 1: pulled on stuff, so it got denser, so it had

359
00:19:21,400 --> 00:19:23,760
Speaker 1: more gravity, et cetera, et cetera. But you never just

360
00:19:23,800 --> 00:19:26,800
Speaker 1: have exactly one seed. Sometimes you have like another nearby,

361
00:19:26,960 --> 00:19:30,479
Speaker 1: smaller seed that resists being pulled in because it has

362
00:19:30,600 --> 00:19:33,399
Speaker 1: enough relative velocity, So it goes into orbit and it

363
00:19:33,400 --> 00:19:37,320
Speaker 1: starts gathering its own stuff. So that's how planets form. Right.

364
00:19:37,320 --> 00:19:40,080
Speaker 1: You have this central blog which absorbs most of the mass,

365
00:19:40,320 --> 00:19:43,520
Speaker 1: but then you have these other seeds nearby which sometimes

366
00:19:43,560 --> 00:19:46,119
Speaker 1: form stars and you get like binary star systems. But

367
00:19:46,200 --> 00:19:49,000
Speaker 1: sometimes they're smaller and they'll form planets in the same

368
00:19:49,040 --> 00:19:52,080
Speaker 1: way as that planet is forming. It makes a proto

369
00:19:52,160 --> 00:19:55,720
Speaker 1: planetary disc. Right. It's a big swirling mass of stuff,

370
00:19:56,000 --> 00:19:58,719
Speaker 1: most of which will collapse into the planet, but some

371
00:19:58,800 --> 00:20:01,240
Speaker 1: of it is going fast enough and has its own

372
00:20:01,320 --> 00:20:05,000
Speaker 1: little gravitational seed, so can form an object which comes

373
00:20:05,040 --> 00:20:07,640
Speaker 1: into orbit around the planet rather than falling in.

374
00:20:08,160 --> 00:20:10,440
Speaker 2: Ah okay, and if it were to slow down, it

375
00:20:10,440 --> 00:20:11,960
Speaker 2: would fall in, but it's not.

376
00:20:12,119 --> 00:20:14,879
Speaker 1: Slowing down exactly. If it were to slow down, then

377
00:20:14,920 --> 00:20:17,400
Speaker 1: it would fall in. And you know, in that initial

378
00:20:17,440 --> 00:20:19,359
Speaker 1: planetary disc there is a lot of friction, and so

379
00:20:19,400 --> 00:20:21,080
Speaker 1: a lot of stuff does fall in. But if you

380
00:20:21,160 --> 00:20:24,399
Speaker 1: survive that and you form, then there's much less friction

381
00:20:24,480 --> 00:20:26,880
Speaker 1: because things have cleared out and you can mostly orbit

382
00:20:26,920 --> 00:20:29,880
Speaker 1: in a stable way. But it depends also on your

383
00:20:29,960 --> 00:20:33,040
Speaker 1: distance from the planet. So for example, if you're too

384
00:20:33,200 --> 00:20:35,160
Speaker 1: close to the planet, you're going to be feeling its

385
00:20:35,200 --> 00:20:39,040
Speaker 1: tidal forces. The planet is a huge gravitational object. And

386
00:20:39,119 --> 00:20:42,200
Speaker 1: remember that gravity depends on distance. The closer you are

387
00:20:42,280 --> 00:20:45,240
Speaker 1: to something, the stronger the gravitational force. The further you

388
00:20:45,240 --> 00:20:48,159
Speaker 1: are from something, the weaker the gravitational force. Now, if

389
00:20:48,200 --> 00:20:50,640
Speaker 1: you are just a point object, that doesn't really matter

390
00:20:50,680 --> 00:20:52,760
Speaker 1: because your front and back are the same thing. But

391
00:20:52,800 --> 00:20:55,280
Speaker 1: if you're big enough that your front and back are

392
00:20:55,320 --> 00:20:58,280
Speaker 1: substantially different, and your front is closer to the planet

393
00:20:58,280 --> 00:21:00,480
Speaker 1: and your back is further from the planet, then a

394
00:21:00,560 --> 00:21:02,719
Speaker 1: planet is going to be pulling on your front harder

395
00:21:02,760 --> 00:21:06,000
Speaker 1: than it's pulling on your back. These are tidal forces. Essentially,

396
00:21:06,000 --> 00:21:08,400
Speaker 1: it's pulling your front and back apart from each other.

397
00:21:08,680 --> 00:21:10,840
Speaker 1: It tends to pull you into like a football shape.

398
00:21:11,119 --> 00:21:13,959
Speaker 1: If you're strong enough internally you're made of diamond, you

399
00:21:14,000 --> 00:21:16,240
Speaker 1: can resist that. But if you're not, you're going to

400
00:21:16,280 --> 00:21:19,440
Speaker 1: get shredded by the tidal forces. This is a mini

401
00:21:19,560 --> 00:21:23,080
Speaker 1: version of like spagetification when you approach a black hole,

402
00:21:23,600 --> 00:21:26,520
Speaker 1: and so a planet has a thing called a roche limit.

403
00:21:26,720 --> 00:21:29,320
Speaker 1: Anything closer to the planet than the roach limit is

404
00:21:29,359 --> 00:21:32,680
Speaker 1: feeling tidal forces that are too strong to survive. Those

405
00:21:32,680 --> 00:21:35,320
Speaker 1: are going to get shredded into like a ring. Anything

406
00:21:35,359 --> 00:21:38,320
Speaker 1: outside the roche limit can hold itself together and stay

407
00:21:38,359 --> 00:21:38,879
Speaker 1: as a moon.

408
00:21:39,080 --> 00:21:41,320
Speaker 2: All right, So you've got your central blob. It's formed

409
00:21:41,320 --> 00:21:43,720
Speaker 2: into a planet. And then I was imagining everything around

410
00:21:43,760 --> 00:21:47,520
Speaker 2: it is a ring. And so I guess when we're

411
00:21:47,560 --> 00:21:50,600
Speaker 2: discussing this roche limit thing, at that point, everything that

412
00:21:50,640 --> 00:21:52,600
Speaker 2: was in the ring has already been sort of pulled

413
00:21:52,720 --> 00:21:57,400
Speaker 2: into the football shape and it got really hard when

414
00:21:57,400 --> 00:21:59,920
Speaker 2: it got pulled into the football shape, and instead of

415
00:22:00,080 --> 00:22:03,040
Speaker 2: getting shredded that it forms the football moon.

416
00:22:03,480 --> 00:22:06,080
Speaker 1: Yeah, you're right. Everything starts as a ring. But if

417
00:22:06,080 --> 00:22:08,160
Speaker 1: you have a ring and it's far enough out, then

418
00:22:08,240 --> 00:22:10,480
Speaker 1: gravity in that ring is going to pull the ring

419
00:22:10,560 --> 00:22:13,119
Speaker 1: together into a moon, ok right, because things in the

420
00:22:13,119 --> 00:22:15,679
Speaker 1: same orbit are going to attract each other along that

421
00:22:15,840 --> 00:22:18,400
Speaker 1: orbit and they'll pull itself together. Now, if you're far

422
00:22:18,480 --> 00:22:21,080
Speaker 1: enough away beyond the roach limit, the planet is not

423
00:22:21,119 --> 00:22:22,880
Speaker 1: going to interfere with that, and you're going to gather

424
00:22:22,960 --> 00:22:26,080
Speaker 1: yourself together into a moon. If you are within the

425
00:22:26,160 --> 00:22:28,439
Speaker 1: roach limit, then the planet is going to interfere with that.

426
00:22:28,520 --> 00:22:30,200
Speaker 1: And as soon as you get any big objects, the

427
00:22:30,200 --> 00:22:32,520
Speaker 1: planet's going to tear them apart or even prevent them

428
00:22:32,520 --> 00:22:35,080
Speaker 1: from forming in the first place, or as we'll talk

429
00:22:35,119 --> 00:22:37,840
Speaker 1: about later. If you have a pre formed object that

430
00:22:37,920 --> 00:22:40,920
Speaker 1: then comes inside the roach limit, the planet will tear

431
00:22:40,920 --> 00:22:43,719
Speaker 1: it apart. So you have rings are formed with the

432
00:22:43,760 --> 00:22:47,439
Speaker 1: planet probably never were moons, if that's really what you're asking.

433
00:22:47,760 --> 00:22:51,879
Speaker 2: Rings that formed with the planet never were moons, but

434
00:22:51,960 --> 00:22:53,080
Speaker 2: could become moons.

435
00:22:53,880 --> 00:22:56,600
Speaker 1: They could become moons if they're outside the roach limit. Yes,

436
00:22:56,640 --> 00:22:59,640
Speaker 1: but rings within the roach limit are probably never were

437
00:22:59,760 --> 00:23:02,880
Speaker 1: moonduns because there's just too strong a tidal force for

438
00:23:02,920 --> 00:23:04,399
Speaker 1: them to pull themselves together.

439
00:23:05,160 --> 00:23:08,200
Speaker 2: So this sounds like an unlikely path to moonhood.

440
00:23:08,480 --> 00:23:10,800
Speaker 1: Yeah, exactly, you need to be outside the roach limit

441
00:23:11,000 --> 00:23:13,400
Speaker 1: in order to be a moon. And so, for example,

442
00:23:13,520 --> 00:23:15,639
Speaker 1: in the Earth moon system, the roach limit is like

443
00:23:15,680 --> 00:23:19,200
Speaker 1: ten thousand kilometers. Anything closer to the Earth than ten

444
00:23:19,240 --> 00:23:21,560
Speaker 1: thousand kilometers you're going to get pulled apart. The Moon

445
00:23:21,640 --> 00:23:24,840
Speaker 1: is safely like three hundred and eighty thousand kilometers away,

446
00:23:25,119 --> 00:23:28,520
Speaker 1: so you're safe. And the Sun also has a roach limit.

447
00:23:28,720 --> 00:23:32,000
Speaker 1: Planets that approach closer than like seven hundred and fifty

448
00:23:32,040 --> 00:23:35,919
Speaker 1: thousand kilometers to the Sun would get shredded. We're safely

449
00:23:35,960 --> 00:23:38,960
Speaker 1: one hundred and fifty million kilometers from the Sun, and

450
00:23:39,000 --> 00:23:41,040
Speaker 1: these roach limits are a little bit fuzzy because an

451
00:23:41,080 --> 00:23:44,320
Speaker 1: object doesn't have a fixed roach limit depends on what

452
00:23:44,359 --> 00:23:46,440
Speaker 1: you're bringing near it. Like if you bring a moon

453
00:23:46,520 --> 00:23:49,840
Speaker 1: made of jello versus the moon made of diamond, they're

454
00:23:49,880 --> 00:23:51,719
Speaker 1: going to get pulled apart at different places, if that

455
00:23:51,760 --> 00:23:52,240
Speaker 1: makes sense.

456
00:23:52,640 --> 00:23:55,879
Speaker 2: And the Moon each year is getting pulled a little

457
00:23:55,920 --> 00:23:58,840
Speaker 2: bit closer to Earth. But it sounds like the difference

458
00:23:58,880 --> 00:24:01,240
Speaker 2: between the roach limit and where the moon is is

459
00:24:01,320 --> 00:24:03,840
Speaker 2: so far there. Oh wait, or is the Moon getting

460
00:24:03,840 --> 00:24:05,280
Speaker 2: farther away from us?

461
00:24:05,720 --> 00:24:08,200
Speaker 1: The Moon is getting further away by the best centimeter

462
00:24:08,320 --> 00:24:11,400
Speaker 1: a year, and it has to do with the angular momentum. Yeah,

463
00:24:11,400 --> 00:24:12,800
Speaker 1: but it is a tidal force effect.

464
00:24:12,800 --> 00:24:14,720
Speaker 2: Also, Okay, are we going to lose the moon?

465
00:24:14,760 --> 00:24:17,119
Speaker 1: Then eventually the Earth and the Moon are going to

466
00:24:17,119 --> 00:24:19,560
Speaker 1: get tidily locked, which will stop this process.

467
00:24:19,800 --> 00:24:23,600
Speaker 2: Okay, good few. Okay, So it sounds like this might

468
00:24:23,960 --> 00:24:25,960
Speaker 2: not be how we got our moon.

469
00:24:26,840 --> 00:24:28,679
Speaker 1: Well, this is not how we got our moon. And

470
00:24:28,720 --> 00:24:31,640
Speaker 1: you can tell which moon's formed with the planet because

471
00:24:31,640 --> 00:24:34,880
Speaker 1: they tend to have a very nice circular orbit and

472
00:24:34,920 --> 00:24:39,119
Speaker 1: to be orbiting the planet around its equator essentially on

473
00:24:39,160 --> 00:24:41,879
Speaker 1: the same axis that the planet is spinning. Because it

474
00:24:41,920 --> 00:24:44,480
Speaker 1: all formed from the same blob of stuff, just like

475
00:24:44,640 --> 00:24:47,159
Speaker 1: most of the planets in the Solar System are orbiting

476
00:24:47,200 --> 00:24:50,840
Speaker 1: the Sun around the same axis that the Sun is rotating,

477
00:24:50,880 --> 00:24:53,359
Speaker 1: because it all came from the same original blob of stuff.

478
00:24:53,800 --> 00:24:57,040
Speaker 1: So if you find a moon around a planet and

479
00:24:57,080 --> 00:24:59,879
Speaker 1: it's got a mostly circular orbit and it's orbiting around

480
00:25:00,000 --> 00:25:03,080
Speaker 1: and the same axis as a planet is spinning, probably

481
00:25:03,160 --> 00:25:04,560
Speaker 1: it formed with the planet.

482
00:25:04,840 --> 00:25:09,080
Speaker 2: WHOA, we got through the boring stuff. All right, Actually

483
00:25:09,320 --> 00:25:11,320
Speaker 2: I thought that was really cool. But okay, so let's

484
00:25:11,400 --> 00:25:11,800
Speaker 2: move on.

485
00:25:12,080 --> 00:25:17,200
Speaker 1: Relatively boring, relatively super exciting, just not the most exciting

486
00:25:17,240 --> 00:25:18,600
Speaker 1: thing we'll talk about today, all.

487
00:25:18,600 --> 00:25:20,600
Speaker 2: Right, all right, so let's move on to something way

488
00:25:20,640 --> 00:25:22,480
Speaker 2: more epic. What's the next method?

489
00:25:22,800 --> 00:25:26,439
Speaker 1: The next method is to capture something. Imagine an object

490
00:25:26,520 --> 00:25:28,800
Speaker 1: that's floating through the Solar System and it comes near

491
00:25:28,840 --> 00:25:31,679
Speaker 1: a planet. Planets have a lot of gravity. If it

492
00:25:31,720 --> 00:25:34,360
Speaker 1: comes in at the right velocity, in the right distance

493
00:25:34,359 --> 00:25:37,520
Speaker 1: and the right angle, it can basically enter orbit around

494
00:25:37,560 --> 00:25:40,320
Speaker 1: a planet the way like a spaceship can approach a

495
00:25:40,359 --> 00:25:42,760
Speaker 1: planet and go into orbit around it, or you can

496
00:25:42,840 --> 00:25:46,480
Speaker 1: launch a satellite into orbit. If visiting rock has the

497
00:25:46,560 --> 00:25:49,800
Speaker 1: right trajectory, it can be captured by a planet. And

498
00:25:49,840 --> 00:25:52,640
Speaker 1: you can tell moons that have this history because they're

499
00:25:52,640 --> 00:25:55,320
Speaker 1: not made of the same stuff as the planet, and

500
00:25:55,520 --> 00:25:58,040
Speaker 1: because they tend to have like weird orbits, they're highly

501
00:25:58,080 --> 00:26:02,240
Speaker 1: elliptical or they're tilted relative to the axis of rotation

502
00:26:02,480 --> 00:26:03,160
Speaker 1: of the planet.

503
00:26:03,560 --> 00:26:05,639
Speaker 2: How many of these do we think we have in

504
00:26:05,680 --> 00:26:08,240
Speaker 2: our Solar system, because that seems like, depending on where

505
00:26:08,240 --> 00:26:10,640
Speaker 2: they came from, a really cool opportunity for science.

506
00:26:11,000 --> 00:26:13,679
Speaker 1: It is a very cool opportunity for science. And we

507
00:26:13,760 --> 00:26:17,000
Speaker 1: have lots and lots of these examples in the Solar System,

508
00:26:17,040 --> 00:26:18,480
Speaker 1: and we'll talk about a few of them in a

509
00:26:18,480 --> 00:26:21,280
Speaker 1: minute when we do the countdown for the ranking of

510
00:26:21,320 --> 00:26:24,320
Speaker 1: the most moons. But it happens quite a bit. And

511
00:26:24,320 --> 00:26:27,760
Speaker 1: astronomers like to think about the region of a planet

512
00:26:27,880 --> 00:26:31,320
Speaker 1: near a planet where its gravity dominates. Because imagine you're

513
00:26:31,359 --> 00:26:33,840
Speaker 1: some rock and basically you're orbiting the Sun and you

514
00:26:33,920 --> 00:26:36,760
Speaker 1: come near the Earth. How close to the Earth you

515
00:26:36,840 --> 00:26:39,800
Speaker 1: have to get before the Earth's gravity dominates over the

516
00:26:39,840 --> 00:26:43,800
Speaker 1: Sun's gravity. That's called the hill sphere. And if a

517
00:26:44,119 --> 00:26:46,600
Speaker 1: rock enters the hill sphere of a planet, then it

518
00:26:46,600 --> 00:26:48,400
Speaker 1: has a chance to become captured.

519
00:26:48,680 --> 00:26:52,480
Speaker 2: And was hill a guy or gal was Hill an astronomer,

520
00:26:53,280 --> 00:26:55,840
Speaker 2: presumably not one with the voice like you were making before.

521
00:26:59,480 --> 00:27:01,800
Speaker 1: Yes, it was an astronomer and someone who thought about

522
00:27:01,960 --> 00:27:05,320
Speaker 1: the early formation of the Solar System, because remember, back

523
00:27:05,320 --> 00:27:08,359
Speaker 1: in the early days, things weren't as well cleared outs.

524
00:27:08,520 --> 00:27:12,280
Speaker 1: There were lots of rocks floating around Jupiter and Saturn

525
00:27:12,480 --> 00:27:14,840
Speaker 1: moved into the inner Solar System and then back out,

526
00:27:14,880 --> 00:27:17,919
Speaker 1: and that threw lots of asteroids everywhere, So there were

527
00:27:18,000 --> 00:27:20,639
Speaker 1: lots of scattered objects. Some of them just get lost

528
00:27:20,960 --> 00:27:24,360
Speaker 1: at a fly outside the Solar System. Eventually maybe get

529
00:27:24,359 --> 00:27:26,960
Speaker 1: captured by another Solar system. Some of them will get

530
00:27:27,000 --> 00:27:29,719
Speaker 1: captured by other planets. But each one is like a

531
00:27:29,760 --> 00:27:33,520
Speaker 1: time capsule of crazy events that happened in our Solar system.

532
00:27:33,720 --> 00:27:37,439
Speaker 2: It sounds like if a giant object comes in that

533
00:27:37,480 --> 00:27:39,919
Speaker 2: would cause a lot of chaos in the process, Like

534
00:27:40,440 --> 00:27:42,720
Speaker 2: does it cause? I mean, I guess if it's small

535
00:27:42,800 --> 00:27:44,800
Speaker 2: enough relative to a planet that it can get captured,

536
00:27:44,800 --> 00:27:46,520
Speaker 2: it's probably not going to cause a lot of chaos

537
00:27:46,600 --> 00:27:49,280
Speaker 2: for the planet that captures it. So maybe it's not

538
00:27:49,280 --> 00:27:52,360
Speaker 2: going to cause that much chaos. How chaotic is this, Daniel.

539
00:27:53,760 --> 00:27:56,520
Speaker 1: Well, the bigger the thing, the more chaos it causes, right,

540
00:27:56,600 --> 00:27:59,680
Speaker 1: because the more gravitational pull it has. But the Solar

541
00:27:59,680 --> 00:28:01,840
Speaker 1: System already has a lot of chaos in it because

542
00:28:01,920 --> 00:28:04,000
Speaker 1: every system that has more than two bodies in it

543
00:28:04,080 --> 00:28:06,880
Speaker 1: is chaotic. You know, it's called the three body problem.

544
00:28:07,160 --> 00:28:10,400
Speaker 1: You can't have very many stable configurations of three objects

545
00:28:10,520 --> 00:28:13,280
Speaker 1: orbiting each other, and the only way to do that

546
00:28:13,440 --> 00:28:15,600
Speaker 1: is to have configurations where like two of them are

547
00:28:15,640 --> 00:28:17,879
Speaker 1: really really far from the other one. So even just

548
00:28:17,920 --> 00:28:20,960
Speaker 1: having like Earth, Sun and Jupiter already is a little

549
00:28:20,960 --> 00:28:23,399
Speaker 1: bit chaotic. Jupiter is pulling on the Earth. That's one

550
00:28:23,440 --> 00:28:25,800
Speaker 1: of the reasons why our orbits are changing, and we

551
00:28:25,920 --> 00:28:29,000
Speaker 1: have these Malkovich cycles where we get further and closer

552
00:28:29,040 --> 00:28:31,159
Speaker 1: from the Sun. So there's already a little bit of

553
00:28:31,240 --> 00:28:34,240
Speaker 1: chaos in the Solar System. So something coming in from

554
00:28:34,240 --> 00:28:37,399
Speaker 1: the outside is definitely going to inject more chaos, and

555
00:28:37,480 --> 00:28:40,840
Speaker 1: most likely chaos causes us to lose things. Being captured

556
00:28:40,880 --> 00:28:42,840
Speaker 1: is rare because you have to come in at like

557
00:28:42,880 --> 00:28:45,440
Speaker 1: the right angle, and you can't be close enough that

558
00:28:45,480 --> 00:28:47,760
Speaker 1: you enter the atmosphere and then drag and then hit

559
00:28:47,800 --> 00:28:49,920
Speaker 1: the planet, and not so far that you're going to

560
00:28:49,920 --> 00:28:52,760
Speaker 1: miss the hillsphere. So it's really just like quite a

561
00:28:52,880 --> 00:28:55,800
Speaker 1: narrow window for things to get captured. So the things

562
00:28:55,880 --> 00:28:57,920
Speaker 1: in the Solar system that are captured are a tiny

563
00:28:58,000 --> 00:29:01,000
Speaker 1: fraction of all the chaos that has flown through our

564
00:29:01,000 --> 00:29:01,640
Speaker 1: solar system.

565
00:29:02,040 --> 00:29:05,080
Speaker 2: So most of the stuff that does get captured and

566
00:29:05,080 --> 00:29:08,240
Speaker 2: become a moon, do we know where it tends to

567
00:29:08,280 --> 00:29:08,720
Speaker 2: come from?

568
00:29:08,960 --> 00:29:11,240
Speaker 1: We don't because we haven't studied a lot of these enough.

569
00:29:11,240 --> 00:29:14,400
Speaker 1: We haven't like landed on them or done spectrometry on

570
00:29:14,440 --> 00:29:16,720
Speaker 1: them in great detail. And you'll see the ones we

571
00:29:16,760 --> 00:29:19,040
Speaker 1: have studied we already have a lot of questions about.

572
00:29:20,080 --> 00:29:24,200
Speaker 2: Well. I also thought that that was pretty awesome, But

573
00:29:24,320 --> 00:29:27,240
Speaker 2: now we're going to get to the most awesome explanation,

574
00:29:27,400 --> 00:29:30,360
Speaker 2: which is collisions, and I agree that is probably the

575
00:29:30,400 --> 00:29:33,440
Speaker 2: most awesome out of all the explanations. So all right, collisions,

576
00:29:33,640 --> 00:29:34,640
Speaker 2: hit me with it, Daniel.

577
00:29:35,240 --> 00:29:37,920
Speaker 1: So imagine you have a planet and it's doing its thing,

578
00:29:38,040 --> 00:29:41,520
Speaker 1: and then like another planet comes and snacks into it,

579
00:29:42,080 --> 00:29:45,640
Speaker 1: and the two planets are vaporized essentially, and they have

580
00:29:45,720 --> 00:29:50,240
Speaker 1: to like coalesce again into molten blobs, and that process

581
00:29:50,280 --> 00:29:53,720
Speaker 1: doesn't always give two objects of the same size. This

582
00:29:54,040 --> 00:29:56,880
Speaker 1: is the leading theory for the formation of Earth. And

583
00:29:57,000 --> 00:30:00,600
Speaker 1: its moon. That there was a proto Earth with a

584
00:30:00,680 --> 00:30:03,120
Speaker 1: huge moon and it was smacked into by like a

585
00:30:03,280 --> 00:30:08,320
Speaker 1: Mars sized planet, which essentially vaporized the surface of the Earth,

586
00:30:08,760 --> 00:30:11,440
Speaker 1: and a huge chunk of stuff was then thrown out

587
00:30:11,480 --> 00:30:14,600
Speaker 1: into orbit, gathered into a ring as it cooled, and

588
00:30:14,640 --> 00:30:18,720
Speaker 1: then formed into a moon. And there's lots of evidence

589
00:30:18,760 --> 00:30:20,840
Speaker 1: of this from the fact that, like the Moon is

590
00:30:20,880 --> 00:30:23,520
Speaker 1: made out of basically the same stuff as the Earth,

591
00:30:23,920 --> 00:30:26,400
Speaker 1: and because of the way the Moon formed and cooled,

592
00:30:26,720 --> 00:30:29,680
Speaker 1: you can tell that had fairly recent activity on it. Also,

593
00:30:29,880 --> 00:30:32,720
Speaker 1: recent studies of the mantle of the Earth has shown

594
00:30:32,800 --> 00:30:36,640
Speaker 1: like actual deposition from this original protoplanet that hid it.

595
00:30:36,640 --> 00:30:39,920
Speaker 1: It's like there's bits of that still leaving an imprint

596
00:30:39,960 --> 00:30:43,040
Speaker 1: on the inner part of the Earth. It's really fascinating,

597
00:30:43,480 --> 00:30:45,640
Speaker 1: and so essentially that like I don't know if that

598
00:30:45,800 --> 00:30:47,560
Speaker 1: really adds a moon or if it just sort of

599
00:30:47,600 --> 00:30:50,920
Speaker 1: like deletes a planet and it creates two new objects.

600
00:30:51,200 --> 00:30:53,640
Speaker 2: All right, So I'm adding a qualifier to my earlier statement,

601
00:30:53,680 --> 00:30:55,320
Speaker 2: this is the most awesome way to make a moon,

602
00:30:55,400 --> 00:30:58,680
Speaker 2: as long as it never happens again in my lifetime

603
00:30:58,720 --> 00:30:59,600
Speaker 2: to my planets.

604
00:30:59,720 --> 00:31:00,520
Speaker 1: Yeah, exactly.

605
00:31:00,640 --> 00:31:02,960
Speaker 2: But it's awesome that it happened long ago.

606
00:31:03,320 --> 00:31:05,240
Speaker 1: It would have been very dramatic to watch, right. I

607
00:31:05,240 --> 00:31:07,720
Speaker 1: wouldn't mind seeing this happen to another planet. You would

608
00:31:07,800 --> 00:31:09,920
Speaker 1: learn a lot about this Solar System as long as,

609
00:31:09,960 --> 00:31:12,959
Speaker 1: of course, nobody was living on it. No critics were

610
00:31:12,960 --> 00:31:14,320
Speaker 1: harmed in this cosmic collision.

611
00:31:14,480 --> 00:31:17,240
Speaker 2: Okay, So let's assume that there are no microbes on Mars.

612
00:31:17,800 --> 00:31:20,560
Speaker 2: If something like this happened to Mars and we were

613
00:31:20,600 --> 00:31:23,600
Speaker 2: watching it, would there be any implications for us, like

614
00:31:23,680 --> 00:31:26,520
Speaker 2: maybe junk would get thrown off Mars and would hit

615
00:31:26,680 --> 00:31:28,960
Speaker 2: up Yeah, would anything happen to us if this happened

616
00:31:28,960 --> 00:31:29,360
Speaker 2: to Mars.

617
00:31:29,480 --> 00:31:31,800
Speaker 1: Oh, for sure, we would be hit by debris from it.

618
00:31:32,000 --> 00:31:35,400
Speaker 1: We're already hit by debris from Mars. When things hit

619
00:31:35,400 --> 00:31:38,120
Speaker 1: the surface of Mars, stuff is thrown out into space

620
00:31:38,160 --> 00:31:39,760
Speaker 1: and some of it lands on the Earth. We have

621
00:31:39,840 --> 00:31:41,920
Speaker 1: found rocks on the surface of the Earth that we

622
00:31:42,000 --> 00:31:46,720
Speaker 1: know come from Mars because they're geologically incompatible with Earth's

623
00:31:46,760 --> 00:31:51,440
Speaker 1: history and perfectly compatible with Mars. So that already happens

624
00:31:51,440 --> 00:31:55,600
Speaker 1: that like Mars's garbage lands on Earth. So if Mars

625
00:31:55,640 --> 00:31:59,760
Speaker 1: gets like massively slammed by a huge impactor and basically shredded,

626
00:32:00,040 --> 00:32:02,160
Speaker 1: then some significant fraction of it is definitely going to

627
00:32:02,240 --> 00:32:02,640
Speaker 1: hit Earth.

628
00:32:02,720 --> 00:32:05,640
Speaker 2: Yeah, given that you are willing to sacrifice all of

629
00:32:05,720 --> 00:32:09,160
Speaker 2: humanity just to talk to aliens for thirty seconds, would

630
00:32:09,160 --> 00:32:12,560
Speaker 2: you risk Earth getting hit by large chunks of Mars

631
00:32:12,600 --> 00:32:15,480
Speaker 2: just so you could see how this would all play out?

632
00:32:15,640 --> 00:32:18,480
Speaker 1: For sure? Plus we would get samples of Mars here

633
00:32:18,520 --> 00:32:21,560
Speaker 1: on Earth. You're the word, Well, how valuable that is? Like,

634
00:32:21,720 --> 00:32:25,040
Speaker 1: we have this incredible, complicated plan to dig up stuff

635
00:32:25,040 --> 00:32:26,680
Speaker 1: on the surface of Mars and send it back to

636
00:32:26,720 --> 00:32:29,680
Speaker 1: Earth for study. So valuable scientifically, but it's going to

637
00:32:29,720 --> 00:32:32,640
Speaker 1: bring back, like, you know, a small amount of Mars.

638
00:32:32,720 --> 00:32:35,600
Speaker 1: If you could like deliver huge chunks of Mars dropped

639
00:32:35,600 --> 00:32:38,040
Speaker 1: into the Pacific or something, Yeah, let's do it.

640
00:32:38,800 --> 00:32:41,680
Speaker 2: One of us studies life and one of us studies

641
00:32:41,760 --> 00:32:45,040
Speaker 2: non life, and it is very clear which one does

642
00:32:45,080 --> 00:32:45,840
Speaker 2: which right now?

643
00:32:46,720 --> 00:32:49,120
Speaker 1: All right, And while the history of Earth's moon and

644
00:32:49,160 --> 00:32:51,400
Speaker 1: this collision is really fastening into a lot of deep

645
00:32:51,440 --> 00:32:54,200
Speaker 1: signs we could dig into there. Today's episode is not

646
00:32:54,280 --> 00:32:56,920
Speaker 1: just a history of Earth's moon, but we wanted to

647
00:32:57,000 --> 00:33:00,240
Speaker 1: do a ranking of which planets have the most.

648
00:33:00,320 --> 00:33:05,760
Speaker 2: Moons, all right, And so we know unfortunately that the

649
00:33:05,840 --> 00:33:08,080
Speaker 2: answer is not Earth.

650
00:33:08,440 --> 00:33:12,480
Speaker 1: That's right, and in shortstanding tradition established on this episode,

651
00:33:12,600 --> 00:33:15,880
Speaker 1: we're going to start with the least exciting examples first.

652
00:33:16,160 --> 00:33:20,600
Speaker 2: That's right, okay, and so well, should we start closest

653
00:33:20,600 --> 00:33:21,080
Speaker 2: to the Sun?

654
00:33:21,400 --> 00:33:24,280
Speaker 1: Yes, and that coincidentally starts us at the end of

655
00:33:24,280 --> 00:33:27,080
Speaker 1: the list the planets with the least moons, and that

656
00:33:27,120 --> 00:33:30,640
Speaker 1: would be Mercury and Venus. Both of these planets have

657
00:33:31,040 --> 00:33:32,280
Speaker 1: zero moons.

658
00:33:32,840 --> 00:33:33,280
Speaker 2: Why.

659
00:33:33,760 --> 00:33:35,800
Speaker 1: The reason is that they are so close to the

660
00:33:35,880 --> 00:33:39,640
Speaker 1: Sun that the Sun's tidal forces will perturb any orbits.

661
00:33:40,200 --> 00:33:43,160
Speaker 1: Like it's really hard to have a three body system

662
00:33:43,440 --> 00:33:45,800
Speaker 1: if those three are close to each other. The only

663
00:33:45,840 --> 00:33:48,160
Speaker 1: way to have a three body stable system is if

664
00:33:48,160 --> 00:33:50,760
Speaker 1: two of them are far enough away. So, for example,

665
00:33:51,120 --> 00:33:52,760
Speaker 1: the Sun and the Earth and the Moon is a

666
00:33:52,800 --> 00:33:55,520
Speaker 1: three body system. Why is that stable Because the Moon

667
00:33:55,560 --> 00:33:57,800
Speaker 1: and the Earth are fairly close to each other and

668
00:33:58,080 --> 00:34:00,840
Speaker 1: both fairly far away from the Sun. If you bring

669
00:34:00,880 --> 00:34:03,640
Speaker 1: that two body system close enough to the Sun, then

670
00:34:03,720 --> 00:34:05,760
Speaker 1: it becomes a three body system and the whole thing

671
00:34:05,880 --> 00:34:09,120
Speaker 1: is chaotic. So basically, the Sun is going to be

672
00:34:09,160 --> 00:34:11,640
Speaker 1: pulling on those moons in a way that makes none

673
00:34:11,640 --> 00:34:12,960
Speaker 1: of those orbits stable.

674
00:34:13,160 --> 00:34:14,719
Speaker 2: So it sounds like you've just said that the Earth

675
00:34:14,760 --> 00:34:17,520
Speaker 2: is the closest planet that could possibly have a moon

676
00:34:17,719 --> 00:34:21,040
Speaker 2: in our solar system. Yeah, how much closer could the

677
00:34:21,160 --> 00:34:24,000
Speaker 2: Earth be and still have a moon? Are we essentially

678
00:34:24,040 --> 00:34:24,600
Speaker 2: at the limit?

679
00:34:24,760 --> 00:34:28,560
Speaker 1: Yeah, great question. It is possible for Mercury or Venus

680
00:34:28,600 --> 00:34:30,960
Speaker 1: to have a moon. It's just that their hill sphere

681
00:34:31,120 --> 00:34:34,480
Speaker 1: is really really small. So for example, for Mercury to

682
00:34:34,520 --> 00:34:36,840
Speaker 1: have a moon, you'd have to have a moon that

683
00:34:37,000 --> 00:34:40,160
Speaker 1: orbits like pretty close above the surface, which would be

684
00:34:40,280 --> 00:34:43,880
Speaker 1: like a super high velocity, And then Mercury would have

685
00:34:43,920 --> 00:34:46,520
Speaker 1: to have like no atmosphere at all because you wouldn't

686
00:34:46,520 --> 00:34:49,040
Speaker 1: want any drag and no like mountains for the moon

687
00:34:49,080 --> 00:34:52,040
Speaker 1: to smash into. So in principle, it is possible for

688
00:34:52,120 --> 00:34:54,319
Speaker 1: Mercury to have a moon, and Venus is like a

689
00:34:54,480 --> 00:34:57,000
Speaker 1: very thick atmosphere, so this should be tricky. But they

690
00:34:57,040 --> 00:34:58,799
Speaker 1: don't have a moon, and it'd be very hard for

691
00:34:58,840 --> 00:35:01,520
Speaker 1: them to get one. You could bring the Earth closer

692
00:35:01,560 --> 00:35:03,640
Speaker 1: to the Sun and still have a moon. We're quite

693
00:35:03,680 --> 00:35:06,600
Speaker 1: a cozy distance from the Sun. I don't know exactly

694
00:35:06,600 --> 00:35:08,000
Speaker 1: the number of how close it could be.

695
00:35:08,239 --> 00:35:11,800
Speaker 2: Okay, Well, Daniel had hinted earlier that there is one

696
00:35:12,000 --> 00:35:16,239
Speaker 2: other candidate for a moon for Earth, and after the

697
00:35:16,280 --> 00:35:18,120
Speaker 2: break he's going to tell you about it.

698
00:35:18,080 --> 00:35:20,040
Speaker 1: And we're going to hear Kelly try to pronounce it.

699
00:35:20,280 --> 00:35:44,319
Speaker 2: Oh, we're back, and there is one other object in

700
00:35:44,360 --> 00:35:48,160
Speaker 2: the sky that is a potential candidate for another moon

701
00:35:48,280 --> 00:35:52,640
Speaker 2: for Earth. It is colloquially referred to as the space being.

702
00:35:53,440 --> 00:35:56,520
Speaker 1: And uh, how was that pronounced, Kelly? Oh?

703
00:35:56,600 --> 00:36:01,560
Speaker 2: I was trying to avoid it, Kriefney. I probably got

704
00:36:01,560 --> 00:36:03,440
Speaker 2: it right on the first try. Right, how would you

705
00:36:03,520 --> 00:36:09,400
Speaker 2: say it? Daniel? Are you looking up the pronunciation? That's cheating,

706
00:36:09,719 --> 00:36:10,480
Speaker 2: that's cheating.

707
00:36:12,680 --> 00:36:15,200
Speaker 1: I have no idea how to pronounce this. It is

708
00:36:15,280 --> 00:36:18,080
Speaker 1: such a weird word. I don't even know the etymology

709
00:36:18,120 --> 00:36:22,160
Speaker 1: of it is, or why anybody would choose this unpronounceable word.

710
00:36:22,600 --> 00:36:25,359
Speaker 1: C r u I t h n E.

711
00:36:25,640 --> 00:36:27,319
Speaker 2: I wait, you're not even going to try And you

712
00:36:27,360 --> 00:36:28,040
Speaker 2: had me do it.

713
00:36:28,120 --> 00:36:32,520
Speaker 1: First about to you interrupted me as I was about

714
00:36:32,560 --> 00:36:34,840
Speaker 1: to give it a try. I was gonna say I

715
00:36:34,840 --> 00:36:39,000
Speaker 1: would call it krithne also, but it's probably something weirder,

716
00:36:39,040 --> 00:36:41,280
Speaker 1: you know, anytime you have these weird combinations of vowels

717
00:36:41,280 --> 00:36:43,840
Speaker 1: in English, you're like, oh, actually it's Croithney or something.

718
00:36:44,440 --> 00:36:47,400
Speaker 1: So I have no idea. Let's call it the space bean.

719
00:36:47,719 --> 00:36:50,160
Speaker 2: That's great, And I'll note the three times you and

720
00:36:50,200 --> 00:36:55,080
Speaker 2: I said it. We did say it differently each time. Yeah, okay,

721
00:36:55,200 --> 00:36:58,200
Speaker 2: all right, through time. That's right. Tell me about the

722
00:36:58,239 --> 00:36:58,759
Speaker 2: space bean.

723
00:36:59,239 --> 00:37:02,200
Speaker 1: So obviously, the Earth has the Moon, which is the

724
00:37:02,239 --> 00:37:04,399
Speaker 1: major moon and the real moon we consider. But there's

725
00:37:04,440 --> 00:37:07,279
Speaker 1: also this funny object called the space bean. This is

726
00:37:07,320 --> 00:37:10,600
Speaker 1: a rock like five kilometers in diameter, and it's not

727
00:37:10,719 --> 00:37:12,920
Speaker 1: shaped like a bean. You might think, oh, does it

728
00:37:12,960 --> 00:37:15,240
Speaker 1: look like a kidney bean or a pindo bean or something.

729
00:37:15,440 --> 00:37:17,520
Speaker 1: It's just that it has a funny orbit. So its

730
00:37:17,640 --> 00:37:21,880
Speaker 1: orbit is kind of being shaped. So it's got this

731
00:37:21,960 --> 00:37:25,600
Speaker 1: elliptical orbit and principle it's orbiting the Sun and not

732
00:37:25,680 --> 00:37:28,200
Speaker 1: the Earth, but it's close enough to the Earth that

733
00:37:28,239 --> 00:37:30,799
Speaker 1: the Earth is also tugging on it, and so it's

734
00:37:30,840 --> 00:37:34,200
Speaker 1: in resonance with the Earth like it's a complicated three

735
00:37:34,280 --> 00:37:38,279
Speaker 1: body system that has found this stability to it. And

736
00:37:38,360 --> 00:37:41,560
Speaker 1: so if you look at its orbit relative to the Earth,

737
00:37:41,640 --> 00:37:44,720
Speaker 1: it moves in this sort of bean shaped pattern. Again

738
00:37:44,880 --> 00:37:48,080
Speaker 1: relative to the Earth, it's not really orbiting the Earth.

739
00:37:48,120 --> 00:37:50,200
Speaker 1: I mean sometimes the Earth is on one side of

740
00:37:50,239 --> 00:37:52,640
Speaker 1: the Sun and the space bean is on the other

741
00:37:52,800 --> 00:37:57,440
Speaker 1: side of the Sun. So it's more like how Jupiter

742
00:37:58,040 --> 00:38:02,040
Speaker 1: has asteroids that follow it and precede it in its orbit,

743
00:38:02,520 --> 00:38:06,120
Speaker 1: because those are stable points, the grange points in the

744
00:38:06,200 --> 00:38:07,719
Speaker 1: Jupiter Sun system.

745
00:38:07,880 --> 00:38:09,440
Speaker 2: Those are the Trojans, right.

746
00:38:09,320 --> 00:38:12,000
Speaker 1: Yes, exactly, the Trojans and the Greeks. You got to

747
00:38:12,080 --> 00:38:18,879
Speaker 1: keep them separated, that's right, exactly. And in the same way,

748
00:38:19,080 --> 00:38:22,680
Speaker 1: there are like some stable patterns in the Earth Sun system,

749
00:38:23,080 --> 00:38:25,359
Speaker 1: and this object has fallen into one of them.

750
00:38:25,760 --> 00:38:28,239
Speaker 2: Danielle, I have very strong opinions that this is not

751
00:38:28,400 --> 00:38:32,680
Speaker 2: a moon. This just does not feel like a moon

752
00:38:32,719 --> 00:38:34,279
Speaker 2: at all. Given what you've just told me. What do

753
00:38:34,320 --> 00:38:36,239
Speaker 2: you think, yes or no? Thumbs up? Thumbs down?

754
00:38:37,480 --> 00:38:39,319
Speaker 1: I mean, it's a fuzzy thing, but I would have

755
00:38:39,400 --> 00:38:43,280
Speaker 1: to say no, right they probably also it's not really captured,

756
00:38:43,320 --> 00:38:46,960
Speaker 1: but it is gravitationally influenced by the Earth. It's not

757
00:38:47,080 --> 00:38:49,680
Speaker 1: just in orbit around the Sun on its own. But

758
00:38:49,719 --> 00:38:51,879
Speaker 1: the thing that pushes me against calling it a moon

759
00:38:52,160 --> 00:38:54,320
Speaker 1: is it never really gets very close to the Earth.

760
00:38:54,719 --> 00:38:56,719
Speaker 1: The closest it ever gets to the Earth is like

761
00:38:56,840 --> 00:38:59,719
Speaker 1: seven and a half million miles away, which is like

762
00:39:00,160 --> 00:39:05,200
Speaker 1: thirty times farther than our current moon. So officially astronomers

763
00:39:05,200 --> 00:39:10,160
Speaker 1: call this a quasi satellite, which is like such a fudge.

764
00:39:09,920 --> 00:39:15,840
Speaker 2: Word, wishy washy. It doesn't influence our songs or mythology.

765
00:39:16,560 --> 00:39:21,000
Speaker 2: I'm I'm not emotionally feeling any connection to the space bean.

766
00:39:21,200 --> 00:39:23,439
Speaker 1: I say no, even in our family, which are big

767
00:39:23,480 --> 00:39:26,239
Speaker 1: lovers of beans and promoters of beans and every part

768
00:39:26,280 --> 00:39:28,959
Speaker 1: of people's lives. I don't think we're pro space bean

769
00:39:29,160 --> 00:39:30,200
Speaker 1: being promoted to Moon.

770
00:39:30,640 --> 00:39:32,799
Speaker 2: I call beino on the space bean.

771
00:39:35,960 --> 00:39:39,839
Speaker 1: All right. So Earth has one moon and the space bean.

772
00:39:40,560 --> 00:39:42,680
Speaker 1: So let's take a step up and talk about Mars.

773
00:39:42,920 --> 00:39:46,040
Speaker 1: Mars has two moons, and both of these moons are

774
00:39:46,040 --> 00:39:49,560
Speaker 1: fascinating because both of them are very likely captured objects

775
00:39:50,040 --> 00:39:53,280
Speaker 1: not formed with the Mars. And they also have awesome

776
00:39:53,360 --> 00:39:57,920
Speaker 1: names Phobos and demos. These things mean fear and dread.

777
00:39:58,719 --> 00:40:01,160
Speaker 2: Who means that they were having a bad day when

778
00:40:01,160 --> 00:40:01,799
Speaker 2: they named them.

779
00:40:01,840 --> 00:40:04,720
Speaker 1: I bet dark, right? So dark?

780
00:40:04,960 --> 00:40:06,920
Speaker 2: Oh, but Mars is the god of war, right, so

781
00:40:06,960 --> 00:40:09,360
Speaker 2: of course you name the moon's something dark.

782
00:40:09,960 --> 00:40:12,480
Speaker 1: Yeah, exactly, And as we'll hear later on, the name

783
00:40:12,520 --> 00:40:14,800
Speaker 1: of the moons does keep in the theme of the

784
00:40:14,880 --> 00:40:17,160
Speaker 1: name of the planet, which is kind of cool, honestly.

785
00:40:18,440 --> 00:40:21,400
Speaker 1: So Phobos is the closer one. It's larger, It's like

786
00:40:21,440 --> 00:40:24,880
Speaker 1: twenty two kilometers in size. It orbits Mars three times

787
00:40:24,960 --> 00:40:29,120
Speaker 1: every Earth day and is slowly losing its orbit because

788
00:40:29,160 --> 00:40:32,040
Speaker 1: of the atmospheric drag from being so close. So in

789
00:40:32,080 --> 00:40:37,680
Speaker 1: fifty million years, just after elon Musk finishes terraforming, Phobos

790
00:40:37,800 --> 00:40:40,759
Speaker 1: is gonna hit Mars. So that's gonna be a cataclysm. Yeah.

791
00:40:40,760 --> 00:40:43,680
Speaker 1: I know he's really worried about like the Sun expanding

792
00:40:43,760 --> 00:40:46,080
Speaker 1: and eventually destroying the Earth in a billion years, but

793
00:40:46,200 --> 00:40:47,440
Speaker 1: like this is much sooner.

794
00:40:48,360 --> 00:40:52,080
Speaker 2: But you know, you could Phobos is pretty small. Yeah,

795
00:40:52,120 --> 00:40:55,440
Speaker 2: you could push Phobos to a different orbit or something.

796
00:40:55,800 --> 00:40:58,000
Speaker 1: Yeah, yeah, probably you could. You could strap a bunch

797
00:40:58,040 --> 00:40:59,960
Speaker 1: of starships on it and push it to It's not

798
00:41:00,120 --> 00:41:02,319
Speaker 1: that big, right, It's twenty two kilometers, so it's it's

799
00:41:02,320 --> 00:41:03,000
Speaker 1: not enormous.

800
00:41:03,200 --> 00:41:06,360
Speaker 2: I mean, there is so many problems with living on Mars.

801
00:41:06,520 --> 00:41:08,160
Speaker 2: I don't know that this is the one that's the

802
00:41:08,200 --> 00:41:08,960
Speaker 2: show stopper.

803
00:41:09,880 --> 00:41:13,320
Speaker 1: No, just added to your list. And Demos is even smaller.

804
00:41:13,320 --> 00:41:17,960
Speaker 1: It's thirteen kilometers and slowered orbits further out every thirty hours.

805
00:41:18,560 --> 00:41:21,360
Speaker 1: And there was a recent visit to Demos, Like we

806
00:41:21,400 --> 00:41:24,000
Speaker 1: didn't land on it, but it came to a close approach.

807
00:41:24,239 --> 00:41:27,640
Speaker 1: This is actually a satellite launched by the Emirates and

808
00:41:27,760 --> 00:41:31,440
Speaker 1: their orbiter called Hope. So this Hope orbiter visited Demos

809
00:41:31,640 --> 00:41:34,320
Speaker 1: and looked at it carefully and learned something interesting. People

810
00:41:34,320 --> 00:41:37,560
Speaker 1: had long thought that Demos was a captured asteroid, and

811
00:41:37,600 --> 00:41:40,680
Speaker 1: Phobos almost certainly is. But it turns out that Demos

812
00:41:40,760 --> 00:41:44,799
Speaker 1: actually has a composition more similar to Mars than we expected,

813
00:41:45,120 --> 00:41:48,359
Speaker 1: so it probably isn't a captured asteroid, and yet it's

814
00:41:48,400 --> 00:41:51,120
Speaker 1: in this weird orbit, so it doesn't seem like it

815
00:41:51,239 --> 00:41:54,440
Speaker 1: formed with the planet. And the solution is that probably

816
00:41:55,040 --> 00:41:57,920
Speaker 1: Demos is an object that was tossed up from some

817
00:41:58,120 --> 00:42:02,520
Speaker 1: other major collision. Right, So, like something hit Mars, and

818
00:42:02,520 --> 00:42:05,160
Speaker 1: as we talked about this, like blows up chunks of

819
00:42:05,200 --> 00:42:07,439
Speaker 1: Mars out into space, some of which land on Earth,

820
00:42:07,480 --> 00:42:09,680
Speaker 1: but some of which could be in just the right

821
00:42:09,719 --> 00:42:12,640
Speaker 1: angle to end up in orbit. So Demos is like

822
00:42:12,680 --> 00:42:14,400
Speaker 1: a rejected piece of Mars.

823
00:42:14,760 --> 00:42:14,920
Speaker 3: Ah.

824
00:42:15,040 --> 00:42:16,920
Speaker 2: But that's not how I think of the Moon. I

825
00:42:16,920 --> 00:42:19,360
Speaker 2: don't think of it as a rejected piece of the Earth.

826
00:42:19,680 --> 00:42:23,240
Speaker 2: You watch your language Daniel, the moon might be listening.

827
00:42:23,960 --> 00:42:26,799
Speaker 1: I mean, its name is dread Okay, I don't think

828
00:42:26,800 --> 00:42:29,560
Speaker 1: it needs to be dressed up in happy language, all right.

829
00:42:29,480 --> 00:42:32,240
Speaker 2: All right, it's probably the goth equivalent of a moon. Yeah,

830
00:42:32,320 --> 00:42:32,800
Speaker 2: mm hmmm.

831
00:42:33,360 --> 00:42:35,600
Speaker 1: And these are moons. We've known about it for quite

832
00:42:35,640 --> 00:42:38,440
Speaker 1: a while. They were seen in the late eighteen hundreds

833
00:42:38,719 --> 00:42:41,959
Speaker 1: by astronomer aesof Hall, So not as long as we've

834
00:42:41,960 --> 00:42:44,320
Speaker 1: known about Jupiter's moons. But like you know, one hundred

835
00:42:44,320 --> 00:42:47,200
Speaker 1: and fifty years or so, these are not recent discoveries.

836
00:42:47,400 --> 00:42:50,000
Speaker 2: Wait, we knew about Jupiter's moons before we knew about

837
00:42:50,000 --> 00:42:50,920
Speaker 2: Mars's moons.

838
00:42:51,480 --> 00:42:55,439
Speaker 1: Yeah, Galileo discovered the first moons of Jupiter. Wow. Yeah,

839
00:42:55,520 --> 00:42:59,040
Speaker 1: quite a long time ago. But those moons are huge, right,

840
00:42:59,080 --> 00:43:00,640
Speaker 1: Some of those are big enough that they would be

841
00:43:00,719 --> 00:43:03,120
Speaker 1: planets if they weren't in orbit around Jupiter.

842
00:43:03,320 --> 00:43:07,120
Speaker 2: Holy cow. All right, So we've got Earth has one

843
00:43:07,239 --> 00:43:12,160
Speaker 2: moon and a bean, Mars has two moons. Does anybody

844
00:43:12,200 --> 00:43:13,560
Speaker 2: have three moons?

845
00:43:14,040 --> 00:43:14,800
Speaker 1: No?

846
00:43:14,800 --> 00:43:20,320
Speaker 2: No, all right, do give me four moons? Nope, five moons,

847
00:43:20,400 --> 00:43:20,920
Speaker 2: five moons.

848
00:43:21,000 --> 00:43:25,160
Speaker 1: We have Pluto right now. Pluto, of course, famous for

849
00:43:25,200 --> 00:43:28,000
Speaker 1: being an astronomical fuzzy territory. Is it a planet, is

850
00:43:28,040 --> 00:43:32,560
Speaker 1: it a dwarf planet? Whatever. Also, it has this weird moon, Sharon.

851
00:43:33,160 --> 00:43:36,759
Speaker 1: So Sharon is super weird because it's almost as big

852
00:43:36,800 --> 00:43:39,759
Speaker 1: as Pluto. It's half the size of Pluto, right, and

853
00:43:39,800 --> 00:43:42,520
Speaker 1: so it really challenges the whole concept of a moon.

854
00:43:43,000 --> 00:43:45,800
Speaker 1: It's more natural to think of the Pluto Sharon system

855
00:43:46,080 --> 00:43:50,880
Speaker 1: its binary dwarf planets. Basically, the reason that Pluto was

856
00:43:50,880 --> 00:43:53,759
Speaker 1: demoted from a planet to dwarf planet is that there's

857
00:43:53,880 --> 00:43:56,160
Speaker 1: many things like Pluto out there, and so if you

858
00:43:56,200 --> 00:43:58,520
Speaker 1: include Pluto, then you've got to include like hundreds and

859
00:43:58,600 --> 00:44:00,719
Speaker 1: hundreds of these things. And people didn't one hundreds and

860
00:44:00,800 --> 00:44:03,759
Speaker 1: hundreds of planets. Why not, I don't know, because they

861
00:44:03,760 --> 00:44:06,160
Speaker 1: wanted to think planets are special because we're on one,

862
00:44:06,280 --> 00:44:08,799
Speaker 1: and they wanted to be a protected category. This whole

863
00:44:08,800 --> 00:44:12,920
Speaker 1: thing is like so arbitrary and cultural and ridiculous. But anyway,

864
00:44:13,200 --> 00:44:15,279
Speaker 1: if you demote it to a dwarf planet, then you

865
00:44:15,320 --> 00:44:18,600
Speaker 1: really should think about Pluto and Sharon as tidally locked

866
00:44:18,800 --> 00:44:20,320
Speaker 1: binary dwarf planets.

867
00:44:20,680 --> 00:44:24,279
Speaker 2: WHOA, And so because you're not referring to Sharon as

868
00:44:24,400 --> 00:44:27,120
Speaker 2: a moon, does that mean that the center of mass

869
00:44:27,800 --> 00:44:30,160
Speaker 2: is somewhere between Pluto and Sharon.

870
00:44:30,320 --> 00:44:33,080
Speaker 1: Okay, yeah, so technically it is a moon, but like

871
00:44:33,719 --> 00:44:37,560
Speaker 1: it violates that definition as well. Okay, yeah, so really

872
00:44:37,560 --> 00:44:42,920
Speaker 1: fascinating system. Plus there's four more small moons. Hubble discovered

873
00:44:42,960 --> 00:44:45,839
Speaker 1: these just like twenty years ago, that there's four more

874
00:44:45,960 --> 00:44:48,880
Speaker 1: little bits orbiting the Pluto Sharon system. So it's a

875
00:44:48,920 --> 00:44:52,040
Speaker 1: really complex little system. They're orbiting each other and then

876
00:44:52,200 --> 00:44:55,320
Speaker 1: orbiting the two of them are four smaller moons further out.

877
00:44:55,760 --> 00:44:56,800
Speaker 1: So it's crazy.

878
00:44:56,920 --> 00:44:59,000
Speaker 2: It's crazy that we know any of this in my

879
00:44:59,160 --> 00:45:03,160
Speaker 2: fat so far away and that's amazing.

880
00:45:03,239 --> 00:45:06,520
Speaker 1: Go us, it's amazing. And there's probably more small moons

881
00:45:06,560 --> 00:45:09,920
Speaker 1: around Pluto. We just haven't seen them, right, because Pluto

882
00:45:10,080 --> 00:45:13,240
Speaker 1: is super far win. Even Hubble is challenged to see

883
00:45:13,280 --> 00:45:16,000
Speaker 1: tiny little moons that are not glowing right. You can

884
00:45:16,040 --> 00:45:19,320
Speaker 1: only see them when photons leave the Sun happy to

885
00:45:19,440 --> 00:45:23,120
Speaker 1: bounce off of these dark objects and come back to Earth.

886
00:45:23,600 --> 00:45:25,720
Speaker 1: And so if that doesn't happen, you don't see it.

887
00:45:25,719 --> 00:45:28,279
Speaker 1: It's too small, you don't see it. And so there's

888
00:45:28,280 --> 00:45:31,920
Speaker 1: almost certainly more moons of Pluto yet to be discovered.

889
00:45:32,040 --> 00:45:34,080
Speaker 1: You could find them and name them after your dog.

890
00:45:34,400 --> 00:45:38,200
Speaker 2: Well, I like that idea, Melo and Biscuit moons. But

891
00:45:38,480 --> 00:45:41,600
Speaker 2: I did read the outline, so I know that even

892
00:45:41,640 --> 00:45:44,839
Speaker 2: if we missed a handful of moons around Pluto, that

893
00:45:44,880 --> 00:45:48,000
Speaker 2: would not give Pluto the wind. So I'm guessing Pluto's

894
00:45:48,040 --> 00:45:50,160
Speaker 2: not going to win. So who is next in our list?

895
00:45:50,400 --> 00:45:52,000
Speaker 1: So next up in the ranking we got to go

896
00:45:52,040 --> 00:45:56,880
Speaker 1: all the way up to sixteen moons. Neptune has sixteen moons,

897
00:45:57,239 --> 00:46:00,080
Speaker 1: all of which are named after water gods, which is

898
00:46:00,160 --> 00:46:04,680
Speaker 1: super awesome. Maybe of course Neptune Poseidon, god of the sea,

899
00:46:04,800 --> 00:46:07,920
Speaker 1: and Neptune has a really dramatic moon with probably a

900
00:46:08,000 --> 00:46:11,480
Speaker 1: very dramatic history. So its biggest moon is called Triton,

901
00:46:11,719 --> 00:46:15,520
Speaker 1: and it was actually discovered only seventeen days after Neptune

902
00:46:15,560 --> 00:46:19,080
Speaker 1: itself was discovered. It's super fun, exactly, and the whole

903
00:46:19,120 --> 00:46:21,720
Speaker 1: history of the discovery of Neptune is really fascinating because

904
00:46:22,320 --> 00:46:27,000
Speaker 1: you can see Neptune in Galileo's logbook, like he was

905
00:46:27,040 --> 00:46:29,160
Speaker 1: observing Jupiter and he was looking at the moons, and

906
00:46:29,200 --> 00:46:31,440
Speaker 1: it just so happens that if you're looking in that

907
00:46:31,480 --> 00:46:34,560
Speaker 1: direction in the sky at that time of year, that

908
00:46:34,719 --> 00:46:37,200
Speaker 1: you would see Neptune. And he saw it there, but

909
00:46:37,239 --> 00:46:39,560
Speaker 1: he thought it was a star, and so it's there

910
00:46:39,600 --> 00:46:41,960
Speaker 1: in his log book. You can go back and reconstruct it.

911
00:46:42,239 --> 00:46:44,680
Speaker 1: And it wasn't until two hundred years later that people

912
00:46:44,719 --> 00:46:47,120
Speaker 1: figured out where Neptune was and saw it because of

913
00:46:47,160 --> 00:46:51,560
Speaker 1: its pull on Urinus. A really whole fascinating scientific history story.

914
00:46:51,600 --> 00:46:53,640
Speaker 1: I love when there's a discovery made, then you can

915
00:46:53,680 --> 00:46:56,360
Speaker 1: go back and find oh, this data actually already existed.

916
00:46:56,400 --> 00:46:59,000
Speaker 1: We could have made that discovery earlier if people had

917
00:46:59,080 --> 00:46:59,879
Speaker 1: recognized it.

918
00:47:00,120 --> 00:47:03,239
Speaker 2: Those are fun moments, yes, amazing, although not fun if

919
00:47:03,280 --> 00:47:06,720
Speaker 2: you're alive to realize that you missed. You missed that moment.

920
00:47:07,000 --> 00:47:09,360
Speaker 1: But what it says is that there's probably data in

921
00:47:09,400 --> 00:47:13,120
Speaker 1: a logbook right now that is enough to support some

922
00:47:13,239 --> 00:47:15,839
Speaker 1: crazy discovery, and we won't realize it until somebody else

923
00:47:15,840 --> 00:47:20,520
Speaker 1: figures it out. Anyway, Trenton is incredible because it orbits

924
00:47:20,719 --> 00:47:25,279
Speaker 1: retrograde to Neptune's rotation. So most moons orbit the same

925
00:47:25,360 --> 00:47:29,200
Speaker 1: direction the planet spins, because either they're formed with the

926
00:47:29,239 --> 00:47:32,920
Speaker 1: moon or they're captured that way. But Trident orbits the

927
00:47:32,960 --> 00:47:38,480
Speaker 1: opposite direction that Neptune spins, which is crazy, and probably

928
00:47:38,520 --> 00:47:41,279
Speaker 1: this is because it's captured. It's some huge object that

929
00:47:41,320 --> 00:47:42,400
Speaker 1: Neptune captured.

930
00:47:42,640 --> 00:47:45,160
Speaker 2: I always thought that retrograde was just a word you

931
00:47:45,200 --> 00:47:49,600
Speaker 2: heard in astrology horoscopes. No, it just means that you're

932
00:47:49,880 --> 00:47:52,440
Speaker 2: orbiting the opposite of the Okay.

933
00:47:52,360 --> 00:47:55,760
Speaker 1: Yeah, exactly like when planets go into retrograde, it's because

934
00:47:55,800 --> 00:47:58,120
Speaker 1: relative to the Earth, they're moving the opposite direction.

935
00:47:58,560 --> 00:47:59,840
Speaker 2: WHOA okay.

936
00:48:00,640 --> 00:48:03,640
Speaker 1: And so probably what happened here is that Neptune had

937
00:48:03,680 --> 00:48:06,520
Speaker 1: a tidy little set of moons and then Triton came

938
00:48:06,560 --> 00:48:09,839
Speaker 1: in and destroyed all of them because it came in

939
00:48:09,880 --> 00:48:12,040
Speaker 1: and it did not it went the wrong direction. It's

940
00:48:12,080 --> 00:48:15,040
Speaker 1: like driving a semi the wrong way on a freeway, right,

941
00:48:15,160 --> 00:48:17,640
Speaker 1: not cool. Yeah, And so it looks like all the

942
00:48:17,719 --> 00:48:20,719
Speaker 1: other moons, the other fifteen moons of Neptune are re

943
00:48:20,880 --> 00:48:24,680
Speaker 1: accretions of the rubble disc from Triton's capture. So Triton

944
00:48:24,680 --> 00:48:28,359
Speaker 1: comes in destroys all the moons, and then eventually they

945
00:48:28,400 --> 00:48:32,400
Speaker 1: gathered themselves together into these pathetic little objects, you know,

946
00:48:32,520 --> 00:48:34,720
Speaker 1: just remnants of this collision with Triton.

947
00:48:35,040 --> 00:48:37,840
Speaker 2: So how could you know the difference between moons that

948
00:48:37,880 --> 00:48:42,640
Speaker 2: were there before and moons that recollected after Triton destroyed everything?

949
00:48:43,239 --> 00:48:46,640
Speaker 1: So they're not in tidy circular orbits around Neptune. So

950
00:48:46,680 --> 00:48:49,600
Speaker 1: they probably are not there historically since the beginning, right,

951
00:48:49,640 --> 00:48:52,319
Speaker 1: because they're affected by this collision, and they seem to

952
00:48:52,320 --> 00:48:55,000
Speaker 1: be all sort of mixed up, a various mishmashs of

953
00:48:55,040 --> 00:48:58,200
Speaker 1: the moons and they're sort of loosely held and so

954
00:48:58,280 --> 00:49:00,880
Speaker 1: they haven't like formed together for a long time.

955
00:49:01,160 --> 00:49:04,320
Speaker 2: Amazing. And then is that all of Neptune's moons.

956
00:49:04,800 --> 00:49:06,800
Speaker 1: Those are the ones we found, and you know, these

957
00:49:06,840 --> 00:49:10,439
Speaker 1: distant planets probably have many smaller moons orbiting far out

958
00:49:10,440 --> 00:49:13,000
Speaker 1: that we just haven't been able to see. But next

959
00:49:13,040 --> 00:49:17,000
Speaker 1: up in the list is Urinus. Urinus has twenty nine moons,

960
00:49:17,640 --> 00:49:20,319
Speaker 1: and these are so many that it's useful to categorize them.

961
00:49:20,400 --> 00:49:23,640
Speaker 1: You've got the inner moons. These are like really small

962
00:49:23,760 --> 00:49:28,160
Speaker 1: objects just above the roche limit, just able to hold

963
00:49:28,239 --> 00:49:32,399
Speaker 1: themselves together. And many of these are found like last year,

964
00:49:32,719 --> 00:49:37,000
Speaker 1: so twenty twenty five with James web'space telescope. They are

965
00:49:37,040 --> 00:49:39,520
Speaker 1: so small and dark that they are not visible in

966
00:49:39,600 --> 00:49:42,239
Speaker 1: the optical and you can only see them in the infrared,

967
00:49:42,880 --> 00:49:45,759
Speaker 1: and so that's why James Web can see them. Move

968
00:49:45,800 --> 00:49:49,080
Speaker 1: a little bit further out. And you've got five major moons,

969
00:49:49,560 --> 00:49:51,839
Speaker 1: some of these are big enough to have things like

970
00:49:52,160 --> 00:49:56,040
Speaker 1: volcanism and internal magma and flow on the inside of them.

971
00:49:56,680 --> 00:50:00,440
Speaker 1: The largest one is Titania, which is one twenty the

972
00:50:00,480 --> 00:50:03,600
Speaker 1: mass of our moon, and this we've known about for

973
00:50:03,680 --> 00:50:08,799
Speaker 1: like more than two hundred years. Are you gonna make

974
00:50:08,840 --> 00:50:13,680
Speaker 1: a Titania urinus joke? Kelly has lost at people.

975
00:50:16,480 --> 00:50:18,959
Speaker 4: I have been trying to not make any comments because

976
00:50:19,000 --> 00:50:21,120
Speaker 4: I feel like there's nothing good that I can say.

977
00:50:21,600 --> 00:50:24,799
Speaker 4: But you know, all the other moons were named after

978
00:50:24,880 --> 00:50:28,200
Speaker 4: things similar, and so you know, I'm wondering, You're why,

979
00:50:28,560 --> 00:50:33,680
Speaker 4: you know, why is it Titania and not you know,

980
00:50:34,160 --> 00:50:38,440
Speaker 4: other butt related things, and so I'm just I'm not gonna, okay,

981
00:50:38,520 --> 00:50:42,000
Speaker 4: but I'm gonna focus on the science and ask you, Daniel,

982
00:50:42,400 --> 00:50:45,000
Speaker 4: is this the first moon we've talked about that could

983
00:50:45,080 --> 00:50:46,399
Speaker 4: have volcanism?

984
00:50:46,640 --> 00:50:48,680
Speaker 1: It is, yes, exactly.

985
00:50:48,440 --> 00:50:50,439
Speaker 2: What an adult I am right now.

986
00:50:50,120 --> 00:50:52,479
Speaker 1: For those of us just after the holidays who've eaten

987
00:50:52,520 --> 00:50:55,600
Speaker 1: a big meal and then, you know, produced something titanic

988
00:50:55,640 --> 00:50:58,560
Speaker 1: of our own and wondered, I wonder if that has

989
00:50:58,600 --> 00:51:03,840
Speaker 1: its own gravity could produce volcanism of its own? You know, yes, exactly,

990
00:51:04,280 --> 00:51:06,799
Speaker 1: And so the history here is also funny because it

991
00:51:06,880 --> 00:51:10,440
Speaker 1: was discovered in seventeen eighty seven, just after the planet

992
00:51:10,480 --> 00:51:13,640
Speaker 1: itself was discovered. But the guy who discovered Titania also

993
00:51:13,719 --> 00:51:17,160
Speaker 1: claimed the discovery four more moons which don't exist. What

994
00:51:17,600 --> 00:51:20,879
Speaker 1: so they were like spurious moons which later people are like, yeah,

995
00:51:20,920 --> 00:51:22,560
Speaker 1: I don't see those. I don't know what you were

996
00:51:22,560 --> 00:51:25,279
Speaker 1: looking at. And so the history here is a little

997
00:51:25,320 --> 00:51:25,880
Speaker 1: bit checkered.

998
00:51:25,960 --> 00:51:35,320
Speaker 2: Did he name the other moons like rectum war fits geer?

999
00:51:35,920 --> 00:51:40,239
Speaker 1: Moving on, outside of the major moons are ten more

1000
00:51:40,320 --> 00:51:43,239
Speaker 1: irregular moons, some of which just discovered in the last

1001
00:51:43,239 --> 00:51:45,600
Speaker 1: couple of years. So you know, this is an area

1002
00:51:45,640 --> 00:51:48,400
Speaker 1: where we are actively learning new things about these planets.

1003
00:51:48,600 --> 00:51:51,040
Speaker 2: Amazing, and what makes an irregular moon? Is it the shape?

1004
00:51:51,280 --> 00:51:54,040
Speaker 1: Mm hmm. These things are not like big enough to

1005
00:51:54,120 --> 00:51:57,480
Speaker 1: have pulled themselves into spheres, and so they're like weird blobs.

1006
00:51:57,719 --> 00:52:01,520
Speaker 1: Some of them were also with weird orbits, probably captured objects. Cool,

1007
00:52:01,840 --> 00:52:04,480
Speaker 1: all right. So then stepping up to Jupiter, this was

1008
00:52:04,560 --> 00:52:08,360
Speaker 1: most people's candidate for having the most moons, just because

1009
00:52:08,480 --> 00:52:11,200
Speaker 1: Jupiter is the mostest of most of the stuff, right,

1010
00:52:11,320 --> 00:52:13,880
Speaker 1: It's got most of the non sun mass in the

1011
00:52:13,920 --> 00:52:18,600
Speaker 1: Solar System, and indeed it has almost one hundred moons. Wow, right,

1012
00:52:19,440 --> 00:52:23,000
Speaker 1: seven counted? Ninety seven moons counted for Jupiter so far,

1013
00:52:23,719 --> 00:52:26,480
Speaker 1: the largest four of which were discovered hundreds of years

1014
00:52:26,480 --> 00:52:27,640
Speaker 1: ago by Galileo.

1015
00:52:27,920 --> 00:52:29,360
Speaker 2: WHOA, way to go, Galileo.

1016
00:52:29,520 --> 00:52:30,120
Speaker 1: Yeah, exactly.

1017
00:52:30,200 --> 00:52:32,760
Speaker 2: Could we all count as moons of the Sun should

1018
00:52:32,760 --> 00:52:33,480
Speaker 2: the Sun win?

1019
00:52:35,040 --> 00:52:38,920
Speaker 1: Are you moons of the Sun? Well? I think moons

1020
00:52:38,920 --> 00:52:39,440
Speaker 1: of the Sun we.

1021
00:52:39,440 --> 00:52:41,560
Speaker 2: Call planets, right, yeah, yeah, okay, I'm sorry, I'll put

1022
00:52:41,560 --> 00:52:44,799
Speaker 2: down the banana peels. Let's all right, the last four

1023
00:52:44,840 --> 00:52:48,359
Speaker 2: discovered by Galileo. Way to go, Galileo. Let's talk about Io.

1024
00:52:48,480 --> 00:52:49,320
Speaker 2: I like Io.

1025
00:52:49,520 --> 00:52:52,480
Speaker 1: Yeah, these moons are huge and likely formed with Jupiter.

1026
00:52:52,520 --> 00:52:55,799
Speaker 1: They're in nice orbits around Jupiter. Io is bigger than

1027
00:52:55,800 --> 00:52:57,799
Speaker 1: our moon. A lot of people think the moon is

1028
00:52:57,800 --> 00:53:01,000
Speaker 1: the biggest moon in the Solar system. Not true, not

1029
00:53:01,080 --> 00:53:03,520
Speaker 1: even the second biggest moon in the Solar system. Io

1030
00:53:03,680 --> 00:53:05,600
Speaker 1: is not even the biggest moon in the Solar system.

1031
00:53:05,840 --> 00:53:07,759
Speaker 1: But it is larger than our moon.

1032
00:53:08,040 --> 00:53:10,799
Speaker 2: What moon is the biggest? Daniel We'll get there.

1033
00:53:10,960 --> 00:53:14,200
Speaker 1: Oh okay, all right, all right, But Io, of course

1034
00:53:14,320 --> 00:53:18,279
Speaker 1: super awesome because it has hundreds of active volcanoes on it,

1035
00:53:18,680 --> 00:53:21,200
Speaker 1: and some of these things shoot plumes out like five

1036
00:53:21,360 --> 00:53:25,680
Speaker 1: hundred kilometers above the surface. It's the most geologically active

1037
00:53:25,719 --> 00:53:27,520
Speaker 1: object in the Solar System.

1038
00:53:27,719 --> 00:53:28,120
Speaker 2: Wow.

1039
00:53:28,200 --> 00:53:30,560
Speaker 1: Yeah. The reason it's got so much going on is

1040
00:53:30,600 --> 00:53:33,000
Speaker 1: that it's pretty close to Jupiter, and so these tidal

1041
00:53:33,040 --> 00:53:35,840
Speaker 1: forces from Jupiter are not strong enough to pull it apart,

1042
00:53:36,160 --> 00:53:38,480
Speaker 1: but they do squeeze it into a football. And then

1043
00:53:38,560 --> 00:53:41,560
Speaker 1: Io also is orbiting, so which part of Io is

1044
00:53:41,560 --> 00:53:44,839
Speaker 1: getting squeezed into a football shape is changing, so sort

1045
00:53:44,840 --> 00:53:47,120
Speaker 1: of from Io's point of view, if you're just looking

1046
00:53:47,160 --> 00:53:49,600
Speaker 1: at it, it's a football, but like different parts of

1047
00:53:49,640 --> 00:53:52,319
Speaker 1: it are getting footballed as it orbits Jupiter and as

1048
00:53:52,360 --> 00:53:55,560
Speaker 1: it spins, so that creates a lot of internal friction.

1049
00:53:56,040 --> 00:53:58,600
Speaker 1: It's just like Jupiter is reaching out with huge cosmic

1050
00:53:58,680 --> 00:54:02,359
Speaker 1: hands and squeezing this thing. It's like kneading dough, right,

1051
00:54:02,440 --> 00:54:06,160
Speaker 1: And so this is tidal heating. So just this gravitational

1052
00:54:06,160 --> 00:54:09,799
Speaker 1: interaction between Io and Jupiter is enough to heat up

1053
00:54:09,840 --> 00:54:12,560
Speaker 1: the inside of Io, and that's where you get all

1054
00:54:12,600 --> 00:54:14,920
Speaker 1: these flows inside of it and this cracking of the

1055
00:54:14,920 --> 00:54:16,560
Speaker 1: surface and all these volcanoes.

1056
00:54:16,800 --> 00:54:19,920
Speaker 2: So is Io really hot in some spots.

1057
00:54:19,520 --> 00:54:22,839
Speaker 1: Then inside of it is very toasty, yes.

1058
00:54:22,600 --> 00:54:27,640
Speaker 2: Absolutely all right, But Europa. Is Europa really hot?

1059
00:54:27,760 --> 00:54:30,640
Speaker 1: Eurrope is fascinating because it's icy on the surface, right,

1060
00:54:30,719 --> 00:54:34,640
Speaker 1: so it's got like a crust of ice. But we've

1061
00:54:34,680 --> 00:54:37,320
Speaker 1: done studies of it and we've seen that Jupiter's magnetic

1062
00:54:37,360 --> 00:54:42,799
Speaker 1: field creates a current inside Europa. What which means probably

1063
00:54:43,040 --> 00:54:47,080
Speaker 1: there's salt water which is capable of conducting electricity inside.

1064
00:54:47,120 --> 00:54:50,680
Speaker 1: So probably you have like ten kilometers of ice and

1065
00:54:50,719 --> 00:54:56,040
Speaker 1: below that maybe like one hundred kilometers of subsurface ocean. Wow,

1066
00:54:56,120 --> 00:54:58,439
Speaker 1: And we think that that's water because as you get

1067
00:54:58,480 --> 00:55:00,560
Speaker 1: closer to the center of Europa, like with many of

1068
00:55:00,560 --> 00:55:03,920
Speaker 1: these moons, tidal heating makes things warm, and so not

1069
00:55:04,000 --> 00:55:06,480
Speaker 1: only is it directly heated because of the friction, but

1070
00:55:06,560 --> 00:55:09,920
Speaker 1: also they're probably like geothermal vents or hydrothermal vents on

1071
00:55:09,960 --> 00:55:12,520
Speaker 1: a moon, where we're heat from the core from this

1072
00:55:12,600 --> 00:55:16,040
Speaker 1: tidal heating is then leaking up equivalent to like a volcano.

1073
00:55:16,600 --> 00:55:20,360
Speaker 1: So you could have enormous quantities of liquid water under

1074
00:55:20,600 --> 00:55:22,800
Speaker 1: this frozen surface on Europa.

1075
00:55:23,000 --> 00:55:24,840
Speaker 2: I would love to know if there's life there.

1076
00:55:25,200 --> 00:55:28,920
Speaker 1: I know, right, so much possibility there for life. And

1077
00:55:28,960 --> 00:55:31,920
Speaker 1: the cool thing is that sometimes it shoots stuff out

1078
00:55:31,960 --> 00:55:35,439
Speaker 1: into space because you get cracks and geysers, and there's

1079
00:55:35,440 --> 00:55:38,680
Speaker 1: a mission being sent Europa Clipper to go and sample

1080
00:55:38,719 --> 00:55:42,440
Speaker 1: these things, like look for microbes or whatever, tiny alien

1081
00:55:42,480 --> 00:55:44,520
Speaker 1: octopi or something so exciting.

1082
00:55:45,120 --> 00:55:47,319
Speaker 2: Yeah, okay, all right, let's get to the largest moon now.

1083
00:55:47,760 --> 00:55:50,560
Speaker 1: So the largest moon in the Solar System is Ganymede,

1084
00:55:50,560 --> 00:55:53,440
Speaker 1: also Jupiter's moon. This thing is two times the mass

1085
00:55:53,440 --> 00:55:55,839
Speaker 1: of our moon. Wow. So if you're like impressed by

1086
00:55:55,840 --> 00:55:59,279
Speaker 1: our moon, like Ganymede is bigger than our moon by

1087
00:55:59,280 --> 00:56:00,520
Speaker 1: a factor of.

1088
00:56:00,200 --> 00:56:03,960
Speaker 2: Two, Well, don't rub it in. Our moon's doing a

1089
00:56:04,000 --> 00:56:05,160
Speaker 2: good job.

1090
00:56:06,520 --> 00:56:08,520
Speaker 1: Again. I mean, is big enough to have an atmosphere,

1091
00:56:08,680 --> 00:56:12,200
Speaker 1: probably has a lot of oxygen in it, also very

1092
00:56:12,280 --> 00:56:14,279
Speaker 1: likely to have a subsurface ocean. We think it has

1093
00:56:14,320 --> 00:56:17,280
Speaker 1: a metal core. This thing has its own magnetic field.

1094
00:56:17,680 --> 00:56:18,480
Speaker 1: It's a monster.

1095
00:56:18,719 --> 00:56:21,160
Speaker 2: But I'm guessing you wouldn't want to live there because

1096
00:56:21,160 --> 00:56:24,560
Speaker 2: proximity to Jupiter would make it uninhabitable. Is that right?

1097
00:56:24,840 --> 00:56:27,440
Speaker 1: Yes, Jupiter puts out a lot of radiation. It's not

1098
00:56:27,480 --> 00:56:29,279
Speaker 1: a star like the Sun, and it's not even a

1099
00:56:29,280 --> 00:56:32,440
Speaker 1: brown dwarf. There's no fusion happening inside of it, but

1100
00:56:32,480 --> 00:56:35,200
Speaker 1: there's still a lot of radiation being pumped off of Jupiter,

1101
00:56:35,280 --> 00:56:36,960
Speaker 1: so not a safe place to live without a lot

1102
00:56:37,000 --> 00:56:40,319
Speaker 1: of shielding, but often the place you'll find settlements in

1103
00:56:40,800 --> 00:56:43,680
Speaker 1: very well written hard sci fi novels, for example, like.

1104
00:56:43,680 --> 00:56:47,480
Speaker 2: The Expanse exactly all right, So Jupiter's got one hundred moons?

1105
00:56:47,480 --> 00:56:49,279
Speaker 2: Are there any other moons that we need to talk

1106
00:56:49,320 --> 00:56:51,080
Speaker 2: about before we move on to our winter?

1107
00:56:51,480 --> 00:56:53,360
Speaker 1: So the third largest moon in the Solar system is

1108
00:56:53,400 --> 00:56:56,799
Speaker 1: also a moon of Jupiter. It's Callisto. Calisto is super

1109
00:56:56,800 --> 00:56:59,240
Speaker 1: interesting because its surface, unlike some of the other ones,

1110
00:56:59,320 --> 00:57:02,840
Speaker 1: is very very old, so lots of craters on the

1111
00:57:02,880 --> 00:57:06,760
Speaker 1: surface of Calisto. Europa, in contrast, has like a really

1112
00:57:06,800 --> 00:57:10,759
Speaker 1: smooth surface, very young surface. It's constantly being reformed, so

1113
00:57:10,760 --> 00:57:13,400
Speaker 1: you get a crater, it gets deleted. Callisto is showing

1114
00:57:13,440 --> 00:57:16,120
Speaker 1: all of its scars, which means it's a great way

1115
00:57:16,160 --> 00:57:18,360
Speaker 1: to understand the history of the Solar system, like when

1116
00:57:18,560 --> 00:57:20,320
Speaker 1: was there a lot of impacts? When wasn't there?

1117
00:57:20,440 --> 00:57:26,720
Speaker 2: Calisto sounds beautiful, but in a different way. Daniel, all right,

1118
00:57:26,760 --> 00:57:28,920
Speaker 2: So Daniel, drum roll please.

1119
00:57:31,720 --> 00:57:33,960
Speaker 1: The drama has been removed by the process of elimination.

1120
00:57:34,160 --> 00:57:37,840
Speaker 1: But the winner is Saturn, and not by a little

1121
00:57:37,840 --> 00:57:42,120
Speaker 1: bit Saturn has two hundred and seventy four moons right

1122
00:57:42,360 --> 00:57:45,760
Speaker 1: Jupiter at ninety seven, Saturn has two hundred and seventy four.

1123
00:57:45,800 --> 00:57:51,200
Speaker 1: It's crazy and these moons are amazing. Also, the biggest

1124
00:57:51,200 --> 00:57:54,160
Speaker 1: one is Titan. This thing is more massive than the

1125
00:57:54,160 --> 00:57:57,680
Speaker 1: planet Mercury. Okay, it's not a small moon. It's huge.

1126
00:57:58,120 --> 00:58:00,680
Speaker 1: You've known about it for hundreds of years. Discovered by

1127
00:58:00,720 --> 00:58:05,040
Speaker 1: Huygens in sixteen fifty five. Another one of my favorite

1128
00:58:05,080 --> 00:58:09,320
Speaker 1: moons in the Solar system is ensuladis this thing like

1129
00:58:09,400 --> 00:58:12,320
Speaker 1: Europa amidst jets of ice, probably because it has a

1130
00:58:12,360 --> 00:58:16,440
Speaker 1: subsurface ocean. It's another great candidate for where life could form.

1131
00:58:16,840 --> 00:58:19,880
Speaker 1: But maybe my favorite moon in the Solar system is

1132
00:58:19,920 --> 00:58:23,360
Speaker 1: this moon of Saturn called Yupitus, which is the craziest

1133
00:58:23,480 --> 00:58:26,960
Speaker 1: name for a moon. But it's shaped like a walnut.

1134
00:58:27,320 --> 00:58:31,120
Speaker 1: It has this enormous ridge all the way around its equator,

1135
00:58:31,520 --> 00:58:35,200
Speaker 1: like this vast set of mountains, and then the top

1136
00:58:35,240 --> 00:58:37,280
Speaker 1: half of it is black and the bottom half of

1137
00:58:37,320 --> 00:58:39,919
Speaker 1: it is white. It's like a black and white cookie. Yes,

1138
00:58:40,680 --> 00:58:44,560
Speaker 1: this thing is crazy, exactly. Somebody took a huge space

1139
00:58:44,640 --> 00:58:47,840
Speaker 1: walnut and dipped half of it in frosting. It's unbelievable.

1140
00:58:48,480 --> 00:58:50,840
Speaker 1: So Saturn has all of these moons, most of them

1141
00:58:50,960 --> 00:58:53,720
Speaker 1: are very far from Saturn, like two hundred and fifty

1142
00:58:53,720 --> 00:58:57,280
Speaker 1: plus of these moons are distant from Saturn, orbiting with

1143
00:58:57,360 --> 00:59:01,600
Speaker 1: high inclinations, almost certainly captured objects of Saturn. Saturn is

1144
00:59:01,640 --> 00:59:04,080
Speaker 1: in a great place to capture all of these objects,

1145
00:59:04,360 --> 00:59:07,600
Speaker 1: many of which are were like scattered by Jupiter, so

1146
00:59:07,880 --> 00:59:10,440
Speaker 1: sort of like the garbage collector of the Solar system.

1147
00:59:10,560 --> 00:59:12,720
Speaker 2: Okay, yes, you were able to tell us that Mercury

1148
00:59:12,760 --> 00:59:14,800
Speaker 2: and Venus are too close to the Sun. That's why

1149
00:59:14,800 --> 00:59:17,960
Speaker 2: they probably don't have any And Saturn probably has the

1150
00:59:18,000 --> 00:59:20,600
Speaker 2: most because it's just in a good position to.

1151
00:59:20,520 --> 00:59:23,360
Speaker 1: Pick up junk exactly. It's got a lot of gravity,

1152
00:59:23,680 --> 00:59:26,560
Speaker 1: and it's far away from the Sun, and it's nearby Jupiter,

1153
00:59:26,600 --> 00:59:29,840
Speaker 1: which creates lots of stuff tossing off of it exactly.

1154
00:59:29,920 --> 00:59:32,920
Speaker 1: So over the years it's picked up a lot of moons.

1155
00:59:33,200 --> 00:59:36,480
Speaker 2: Amazing. If you could visit any moon, Daniel, would it

1156
00:59:36,480 --> 00:59:39,040
Speaker 2: be Yapitus? Is that how you said it?

1157
00:59:39,560 --> 00:59:42,720
Speaker 1: Well, there's another moon of Saturn called Rhea, which they

1158
00:59:42,720 --> 00:59:47,160
Speaker 1: think might have rings, right, because moons can have rings

1159
00:59:47,240 --> 00:59:49,960
Speaker 1: usually that's unusual because the tidal effects of the planet

1160
00:59:49,960 --> 00:59:52,800
Speaker 1: will disrupt it. And this is why, for example, moons

1161
00:59:52,880 --> 00:59:56,160
Speaker 1: tend to not have moons, but it's easier to have

1162
00:59:56,280 --> 00:59:59,840
Speaker 1: rings than moons because they're basically already torn into shreds.

1163
01:00:00,240 --> 01:00:02,000
Speaker 1: So that would be pretty awesome to be on a

1164
01:00:02,080 --> 01:00:04,640
Speaker 1: moon of Saturn, see the rings of Saturn and the

1165
01:00:04,760 --> 01:00:07,600
Speaker 1: rings of Rhea around it. That would be pretty awesome.

1166
01:00:07,680 --> 01:00:08,880
Speaker 2: That would be absolutely epic.

1167
01:00:08,960 --> 01:00:11,960
Speaker 1: Yeah, and not included in today's list are the three

1168
01:00:12,120 --> 01:00:15,200
Speaker 1: hundred and thirty four minor planets in our Solar system

1169
01:00:15,360 --> 01:00:16,640
Speaker 1: that have their own moons.

1170
01:00:16,840 --> 01:00:17,120
Speaker 2: Wow.

1171
01:00:17,200 --> 01:00:21,280
Speaker 1: These things you might call moon moons or moonlitz aw.

1172
01:00:21,720 --> 01:00:24,600
Speaker 2: Moonlits is cute, but moon moons is funner.

1173
01:00:24,920 --> 01:00:29,080
Speaker 1: Yeah, exactly. Moon moons technically reserved for moons that have

1174
01:00:29,200 --> 01:00:32,120
Speaker 1: their own moons. We haven't found any of those yet,

1175
01:00:32,160 --> 01:00:34,320
Speaker 1: but it depends on you whether you call these minor

1176
01:00:34,320 --> 01:00:37,520
Speaker 1: planets moons. And we're all looking forward to the day

1177
01:00:37,640 --> 01:00:42,280
Speaker 1: when we can discover exo moons moons around planets in

1178
01:00:42,400 --> 01:00:46,520
Speaker 1: other Solar systems. It's particularly tricky because the techniques that

1179
01:00:46,560 --> 01:00:50,240
Speaker 1: we have for finding exoplanets are good at finding planets

1180
01:00:50,240 --> 01:00:52,600
Speaker 1: like really close to the Sun that are really big

1181
01:00:52,920 --> 01:00:55,439
Speaker 1: and it's hard for those planets to have moons they're

1182
01:00:55,440 --> 01:00:58,240
Speaker 1: so close to their star. But people are working on this,

1183
01:00:58,640 --> 01:01:02,400
Speaker 1: and direct imaging of planetary discs might help us discover

1184
01:01:02,560 --> 01:01:03,400
Speaker 1: exo moons.

1185
01:01:03,680 --> 01:01:05,920
Speaker 2: I am hoping that this happens in my lifetime. I

1186
01:01:05,920 --> 01:01:07,320
Speaker 2: don't know. There's been a lot of I mean, just

1187
01:01:07,360 --> 01:01:09,919
Speaker 2: hearing you talk today, there's been a lot of cool

1188
01:01:09,920 --> 01:01:13,360
Speaker 2: stuff in our solar system that's been discovered in our lifetimes.

1189
01:01:13,800 --> 01:01:16,080
Speaker 2: I don't know. Maybe we'll start discovering even more cool

1190
01:01:16,080 --> 01:01:18,160
Speaker 2: stuff in other solar systems in our lifetimes. I don't

1191
01:01:18,160 --> 01:01:19,000
Speaker 2: think it's impossible.

1192
01:01:19,120 --> 01:01:21,640
Speaker 1: Yeah, and I should say there are already candidates for

1193
01:01:21,800 --> 01:01:24,959
Speaker 1: exo moons because in some of these eclipse methods, where

1194
01:01:24,960 --> 01:01:27,240
Speaker 1: like a planet passes in front of the star, you

1195
01:01:27,280 --> 01:01:30,120
Speaker 1: can see deviations from those that might be consistent with

1196
01:01:30,160 --> 01:01:32,880
Speaker 1: the moon going around that. But these are just candidates

1197
01:01:32,880 --> 01:01:35,360
Speaker 1: and unconfirmed, and of course there's lots of controversy. So

1198
01:01:35,400 --> 01:01:37,960
Speaker 1: I think we might be on the verge of discovering

1199
01:01:38,080 --> 01:01:38,920
Speaker 1: exo moons.

1200
01:01:39,120 --> 01:01:43,120
Speaker 2: Well, stay tuned. If we find moon moons or exo moons,

1201
01:01:43,320 --> 01:01:44,120
Speaker 2: we will let you know.

1202
01:01:45,200 --> 01:01:48,520
Speaker 1: And one day when we visit another system studying their

1203
01:01:48,560 --> 01:01:51,720
Speaker 1: moons will help us understand the history of that solar system,

1204
01:01:51,760 --> 01:01:55,760
Speaker 1: the cataclysms, the captures, the collisions, everything that went down

1205
01:01:55,920 --> 01:01:57,240
Speaker 1: in their cosmic.

1206
01:01:56,880 --> 01:01:59,360
Speaker 2: Chaos, all of the chaos from the kind of boring

1207
01:01:59,400 --> 01:02:02,040
Speaker 2: stuff Daniel will still tell us about anyway, so the

1208
01:02:02,160 --> 01:02:05,480
Speaker 2: much more exciting stuff, all of which we'll explain in

1209
01:02:05,520 --> 01:02:08,160
Speaker 2: an exciting way. Here a Daniel and kill.

1210
01:02:08,160 --> 01:02:12,280
Speaker 1: All exciting because some of it's more boring anyway. Thanks

1211
01:02:12,280 --> 01:02:14,200
Speaker 1: for tuning in, everyone, and for ficking it out for

1212
01:02:14,240 --> 01:02:17,240
Speaker 1: this countdown for which planet has the most moons.

1213
01:02:24,160 --> 01:02:28,000
Speaker 2: Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We

1214
01:02:28,040 --> 01:02:29,520
Speaker 2: would love to hear from you.

1215
01:02:29,560 --> 01:02:32,520
Speaker 1: We really would. We want to know what questions you

1216
01:02:32,720 --> 01:02:35,360
Speaker 1: have about this Extraordinary Universe.

1217
01:02:35,480 --> 01:02:38,400
Speaker 2: We want to know your thoughts on recent shows, suggestions

1218
01:02:38,400 --> 01:02:41,400
Speaker 2: for future shows. If you contact us, we will get

1219
01:02:41,440 --> 01:02:41,840
Speaker 2: back to you.

1220
01:02:42,120 --> 01:02:45,640
Speaker 1: We really mean it. We answer every message. Email us

1221
01:02:45,680 --> 01:02:48,880
Speaker 1: at Questions at Danielankelly.

1222
01:02:47,960 --> 01:02:50,000
Speaker 2: Dot org, or you can find us on social media.

1223
01:02:50,120 --> 01:02:53,960
Speaker 2: We have accounts on x, Instagram, Blue Sky and on

1224
01:02:54,000 --> 01:02:55,960
Speaker 2: all of those platforms. You can find us at D

1225
01:02:56,400 --> 01:02:57,920
Speaker 2: and K Universe.

1226
01:02:58,160 --> 01:02:59,800
Speaker 1: Don't be shy write to us.

1227
01:03:00,040 --> 01:03:01,160
Speaker 2: The foll