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These are the user uploaded subtitles that are being translated: 1 00:00:04,860 --> 00:00:07,960 We thought we knew our solar system. 2 00:00:07,960 --> 00:00:11,560 Turns out we were wrong. 3 00:00:11,560 --> 00:00:13,830 Groundbreaking observations suggest 4 00:00:13,830 --> 00:00:16,370 an unseen ninth planet 5 00:00:16,370 --> 00:00:21,070 may be out there on the fringes of our solar system. 6 00:00:21,070 --> 00:00:23,170 And it could be huge, 7 00:00:23,180 --> 00:00:26,540 5,000 times more massive than Pluto 8 00:00:26,550 --> 00:00:29,210 and 10 times the mass of the Earth. 9 00:00:29,220 --> 00:00:31,580 We don't get a lot of revolutions in astronomy. 10 00:00:31,580 --> 00:00:35,520 And here we are on the cusp of a discovery like this. 11 00:00:35,520 --> 00:00:36,990 It's crazy to think that, 12 00:00:36,990 --> 00:00:38,860 as much as we've looked into the universe, 13 00:00:38,860 --> 00:00:42,930 that there's this ninth planet out there that we've never seen. 14 00:00:42,930 --> 00:00:45,930 If planet 9 really is out there, 15 00:00:45,930 --> 00:00:48,270 what will it be like? 16 00:00:48,270 --> 00:00:50,670 Is it a rocky super-Earth, 17 00:00:50,670 --> 00:00:53,070 an icy mega-Pluto, 18 00:00:53,070 --> 00:00:56,310 or a gassy mini-Neptune? 19 00:00:56,310 --> 00:00:59,240 Or is planet 9 an alien world 20 00:00:59,250 --> 00:01:02,050 stolen from another star? 21 00:01:02,050 --> 00:01:05,620 And could it provide an unlikely home for life 22 00:01:05,620 --> 00:01:09,490 100 billion miles from the Sun? 23 00:01:09,490 --> 00:01:12,560 ...Captions by vitac... www.Vitac.Com 24 00:01:12,560 --> 00:01:15,530 Captions paid for by Discovery communications 25 00:01:23,670 --> 00:01:25,770 Take a look at the night sky. 26 00:01:25,770 --> 00:01:27,240 The pattern of stars 27 00:01:27,240 --> 00:01:30,570 that drifts overhead appears fixed. 28 00:01:30,580 --> 00:01:33,680 But look for longer, weeks or months, 29 00:01:33,680 --> 00:01:38,220 and you'll see a handful of the points move. 30 00:01:38,220 --> 00:01:41,320 These slow-moving points of light are the planets, 31 00:01:41,320 --> 00:01:43,520 the giant chunks of rock or gas 32 00:01:43,520 --> 00:01:46,560 that orbit our home star, the Sun. 33 00:01:46,560 --> 00:01:49,230 We thought there were eight. 34 00:01:49,230 --> 00:01:50,560 We were wrong. 35 00:01:50,560 --> 00:01:52,760 You know, we think we understand something 36 00:01:52,770 --> 00:01:54,200 as simple as our solar system. 37 00:01:54,200 --> 00:01:56,270 We've found all the planets. 38 00:01:56,270 --> 00:02:00,900 And, right in front of us, we missed something big. 39 00:02:00,910 --> 00:02:05,340 A group of astronomers are studying the Kuiper belt, 40 00:02:05,340 --> 00:02:07,740 a vast band of icy asteroids 41 00:02:07,750 --> 00:02:12,350 that sits way, way outside the orbit of Neptune. 42 00:02:12,350 --> 00:02:15,790 Most of these objects move in a neat, circular formation 43 00:02:15,790 --> 00:02:17,550 around the Sun. 44 00:02:17,560 --> 00:02:20,760 But the astronomers are puzzled by a small group 45 00:02:20,760 --> 00:02:22,990 that appear to break the rules, 46 00:02:23,000 --> 00:02:25,830 swinging far outside the main belt 47 00:02:25,830 --> 00:02:29,470 on wild, extended orbits. 48 00:02:29,470 --> 00:02:32,940 Something sitting far outside the Kuiper belt 49 00:02:32,940 --> 00:02:36,670 seems to be pulling these asteroids out of line, 50 00:02:36,680 --> 00:02:40,280 something the size of a giant planet. 51 00:02:42,350 --> 00:02:44,510 Caltech astronomer Mike Brown hears 52 00:02:44,520 --> 00:02:46,750 about the wild observations 53 00:02:46,750 --> 00:02:51,120 and is determined to prove the planet theory wrong. 54 00:02:51,120 --> 00:02:52,360 When we saw these alignments of all 55 00:02:52,360 --> 00:02:54,190 these objects out there, we thought, 56 00:02:54,190 --> 00:02:55,730 "ugh, everybody's gonna say there's a planet. 57 00:02:55,730 --> 00:02:58,860 We have to very strongly prove there's not a planet." 58 00:02:58,860 --> 00:03:00,500 Because, of course, we all know 59 00:03:00,500 --> 00:03:05,040 there's not another planet out there. That's ridiculous. 60 00:03:05,040 --> 00:03:08,210 Mike asked his colleague, Konstantin Batygin, 61 00:03:08,210 --> 00:03:10,070 to run a computer simulation 62 00:03:10,080 --> 00:03:13,010 to see what effect a ninth planet 63 00:03:13,010 --> 00:03:15,410 should have on the Kuiper belt. 64 00:03:15,410 --> 00:03:17,610 Stunningly, the simulation predicts 65 00:03:17,620 --> 00:03:20,450 elongated orbits identical 66 00:03:20,450 --> 00:03:22,720 to ones already observed. 67 00:03:22,720 --> 00:03:25,920 But the simulation also spits out a surprise. 68 00:03:25,920 --> 00:03:29,030 There should be a second set of rogue orbits 69 00:03:29,030 --> 00:03:31,700 that are perpendicular to the first set. 70 00:03:31,700 --> 00:03:33,900 If Mike can locate these weird 71 00:03:33,900 --> 00:03:37,330 predicted objects inside the Kuiper belt, 72 00:03:37,340 --> 00:03:41,440 planet 9 is almost certainly real. 73 00:03:41,440 --> 00:03:44,810 I took these simulation results to Mike's office 74 00:03:44,810 --> 00:03:47,480 just a couple doors down from my office. 75 00:03:47,480 --> 00:03:49,680 And I said, "look!" You know, "we've got a huge problem!" 76 00:03:49,680 --> 00:03:51,010 He said, "no!" 77 00:03:51,020 --> 00:03:54,550 There's an object called 2012 dr30 78 00:03:54,550 --> 00:03:58,720 "which has an orbit just like the one you're predicting." 79 00:03:58,720 --> 00:04:01,790 Mike's asteroid fits the prediction perfectly. 80 00:04:01,790 --> 00:04:05,830 He searches the records for more and finds another four 81 00:04:05,830 --> 00:04:08,100 that seem to be in the right area. 82 00:04:08,100 --> 00:04:12,370 But just how closely will they fit the prediction? 83 00:04:12,370 --> 00:04:15,340 I remember sitting back and thinking, 84 00:04:15,340 --> 00:04:18,340 "okay, we're going to, right now, plot the data, 85 00:04:18,340 --> 00:04:22,550 the real observational data on top of the model." 86 00:04:22,550 --> 00:04:24,610 And Mike said, "if these two match up, 87 00:04:24,620 --> 00:04:26,980 my jaw is just gonna drop to the floor." 88 00:04:26,990 --> 00:04:31,150 The theory says they should be right here and right here. 89 00:04:31,160 --> 00:04:32,990 And I did the calculations very quickly 90 00:04:32,990 --> 00:04:36,230 to see where they were and brought them up. 91 00:04:36,230 --> 00:04:39,860 And there they are. One, two, three, four, five, 92 00:04:39,870 --> 00:04:41,400 right on these lines 93 00:04:41,400 --> 00:04:44,470 exactly where we predicted they should be. 94 00:04:44,470 --> 00:04:47,040 The moment we saw this, 95 00:04:47,040 --> 00:04:48,910 we went from cautious 96 00:04:48,910 --> 00:04:51,270 to "holy cow! This really is there!" 97 00:04:51,280 --> 00:04:53,540 We have to make sure to tell everybody right away 98 00:04:53,550 --> 00:04:56,250 "because it's actually real!" 99 00:04:56,250 --> 00:04:58,780 Mike and Konstantin had unlocked 100 00:04:58,780 --> 00:05:01,350 the solar system's greatest secret. 101 00:05:01,350 --> 00:05:05,460 Planet 9 was almost certainly real. 102 00:05:05,460 --> 00:05:07,090 And it had to be huge, 103 00:05:07,090 --> 00:05:10,330 perhaps 10 times the mass of Earth. 104 00:05:10,330 --> 00:05:12,730 We're not talking about something like our moon 105 00:05:12,730 --> 00:05:14,600 or Pluto. We're talking about something 106 00:05:14,600 --> 00:05:17,770 that is literally planet-sized. 107 00:05:17,770 --> 00:05:20,370 And we're seeing its gravitational wake 108 00:05:20,370 --> 00:05:21,710 affecting these other objects. 109 00:05:21,710 --> 00:05:23,840 The idea that there could be a giant planet 110 00:05:23,840 --> 00:05:25,640 that we've never seen is something I think 111 00:05:25,640 --> 00:05:27,710 most of people wouldn't have bet on. 112 00:05:27,710 --> 00:05:30,980 But the evidence is remarkable! 113 00:05:30,980 --> 00:05:33,280 To prove planet 9 exists, 114 00:05:33,290 --> 00:05:36,490 astronomers need to see it with their telescopes. 115 00:05:36,490 --> 00:05:38,620 But there's a problem. 116 00:05:38,620 --> 00:05:41,360 Computer simulations only give a broad idea 117 00:05:41,360 --> 00:05:43,490 of where to find it. 118 00:05:43,500 --> 00:05:46,300 And planet 9 is incredibly faint 119 00:05:46,300 --> 00:05:49,500 and almost inconceivably far away. 120 00:05:49,500 --> 00:05:51,330 It's much, much farther out 121 00:05:51,340 --> 00:05:53,600 than we ever expected to find planets. 122 00:05:53,610 --> 00:05:55,240 It probably spends most of its life, 123 00:05:55,240 --> 00:05:56,540 if it's on an elliptical orbit, 124 00:05:56,540 --> 00:05:59,440 so far away from the Sun that we just missed it. 125 00:06:05,920 --> 00:06:09,620 So just how far away is planet 9? 126 00:06:09,620 --> 00:06:12,920 The only way to truly appreciate its vast orbit 127 00:06:12,930 --> 00:06:16,130 is to build a scale model, 128 00:06:16,130 --> 00:06:19,730 perhaps the biggest working model of the solar system 129 00:06:19,730 --> 00:06:23,030 ever attempted. 130 00:06:23,040 --> 00:06:27,040 Planetary scientist Kevin Walsh is here to call the shots. 131 00:06:27,040 --> 00:06:30,670 And he starts with the size of the Sun. 132 00:06:30,680 --> 00:06:33,240 So what we've got here, our kickball, 133 00:06:33,250 --> 00:06:36,880 is going to set the scale of our mini-solar system today. 134 00:06:36,880 --> 00:06:40,220 So everything is scaled off of its relative size 135 00:06:40,220 --> 00:06:43,620 compared to the size of the Sun. 136 00:06:43,620 --> 00:06:45,860 Kevin quickly paces out the position 137 00:06:45,860 --> 00:06:48,020 of the inner rocky planets. 138 00:06:48,030 --> 00:06:52,660 All four sit within 60 yards of the Sun on this scale. 139 00:06:52,660 --> 00:06:56,970 And each planet would appear no bigger than a peppercorn. 140 00:06:56,970 --> 00:06:59,700 To make this a working solar system, 141 00:06:59,710 --> 00:07:01,610 we need to bring on the drones. 142 00:07:16,150 --> 00:07:19,090 Each drone represents a different planet. 143 00:07:19,090 --> 00:07:20,490 And the orbital speeds 144 00:07:20,490 --> 00:07:23,290 have been scaled so one Earth year 145 00:07:23,300 --> 00:07:25,760 takes just 30 seconds. 146 00:07:27,800 --> 00:07:29,230 Already, it's clear to see 147 00:07:29,230 --> 00:07:32,300 how tightly bunched these inner planets are, 148 00:07:32,300 --> 00:07:34,240 and how the closest planets 149 00:07:34,240 --> 00:07:36,770 orbit faster than those farther out. 150 00:07:42,250 --> 00:07:45,350 Far beyond the tightly packed rocky planets 151 00:07:45,350 --> 00:07:48,750 lies the first of the gas giant planets, 152 00:07:48,750 --> 00:07:52,420 on this scale, just over a football field from the Sun. 153 00:07:54,560 --> 00:07:57,390 So, after this 400-foot walk, we made to to Jupiter, 154 00:07:57,400 --> 00:07:59,700 the largest planet in the solar system. 155 00:07:59,700 --> 00:08:01,000 But, even by this size scale, 156 00:08:01,000 --> 00:08:04,170 Jupiter is only about the size of a lollipop. 157 00:08:06,200 --> 00:08:08,910 Another football-field length lies ahead 158 00:08:08,910 --> 00:08:11,610 on the walk to Saturn. 159 00:08:11,610 --> 00:08:14,340 As we look back across the lake bed, 160 00:08:14,350 --> 00:08:15,780 I can barely see the drones. 161 00:08:15,780 --> 00:08:18,880 We covered a huge distance. 162 00:08:18,880 --> 00:08:21,790 The trek out to Uranus is bigger still, 163 00:08:21,790 --> 00:08:23,320 three football fields 164 00:08:23,320 --> 00:08:25,690 or the length of an aircraft carrier. 165 00:08:25,690 --> 00:08:28,790 Turns out there's a lot of wind in the outer solar system! 166 00:08:28,790 --> 00:08:32,500 So I have to yell. 167 00:08:32,500 --> 00:08:34,830 Surprising amount of wind in the outer solar system. 168 00:08:37,170 --> 00:08:40,670 Tumbleweed, rattlesnakes. 169 00:08:40,670 --> 00:08:44,840 After Uranus, it's around 200 yards out to Neptune. 170 00:08:44,840 --> 00:08:47,140 Before the discovery of planet 9, 171 00:08:47,150 --> 00:08:50,650 we thought Neptune was the farthest planet from the Sun, 172 00:08:50,650 --> 00:08:53,320 around half a mile on the scale of our model. 173 00:08:53,320 --> 00:08:56,320 But Neptune's distant orbit is nothing 174 00:08:56,320 --> 00:08:59,690 compared to the orbit of planet 9. 175 00:08:59,690 --> 00:09:00,890 So here we are. 176 00:09:00,890 --> 00:09:03,030 We made it to the orbit of Neptune. 177 00:09:03,030 --> 00:09:05,400 We're only at the tip of the iceberg. 178 00:09:05,400 --> 00:09:07,160 We need to stop measuring in feet. 179 00:09:07,170 --> 00:09:08,770 And we need to start thinking in miles. 180 00:09:08,770 --> 00:09:11,370 We need a car to get out to planet 9. 181 00:09:17,880 --> 00:09:22,150 Planet 9 swings out on a highly elliptical orbit. 182 00:09:22,150 --> 00:09:24,110 Its closest pass to the Sun 183 00:09:24,120 --> 00:09:27,620 is a whopping 19 billion miles. 184 00:09:27,620 --> 00:09:30,850 That's six times wider than the orbit of Neptune. 185 00:09:30,860 --> 00:09:33,160 But, at its farthest point, 186 00:09:33,160 --> 00:09:37,790 planet 9 is 112 billion miles away. 187 00:09:37,800 --> 00:09:42,230 And, on this scale, that's an incredible 18 miles 188 00:09:42,230 --> 00:09:44,970 from our kickball-sized Sun. 189 00:09:44,970 --> 00:09:47,040 So we're here, end of the road. 190 00:09:47,040 --> 00:09:49,110 We've driven about 18 miles 191 00:09:49,110 --> 00:09:51,470 from where we first started setting up the solar system. 192 00:09:51,480 --> 00:09:53,410 But, in the scale of the solar system, 193 00:09:53,410 --> 00:09:55,350 it's over 100 billion miles. 194 00:09:55,350 --> 00:09:57,880 100 billion miles 195 00:09:57,880 --> 00:10:01,220 to get out to the furthest part of planet 9's orbit. 196 00:10:01,220 --> 00:10:02,690 So, to scale, 197 00:10:02,690 --> 00:10:04,950 and we don't know what planet 9 would look like, 198 00:10:04,960 --> 00:10:08,560 but it's probably about the size of a B.B. 199 00:10:08,560 --> 00:10:10,790 So this is the challenge for our astronomers. 200 00:10:10,800 --> 00:10:14,100 How do you see a b.B. From 18 miles away? 201 00:10:14,100 --> 00:10:16,430 This is what we have to do. 202 00:10:16,440 --> 00:10:18,740 It could take years for our telescopes 203 00:10:18,740 --> 00:10:22,440 to pick out an object so impossibly faint, 204 00:10:22,440 --> 00:10:24,640 far away as planet 9. 205 00:10:24,640 --> 00:10:27,740 Until then, scientists can only speculate 206 00:10:27,750 --> 00:10:31,380 on what this mysterious world might be like. 207 00:10:31,380 --> 00:10:33,780 We're in this wonderful moment right now 208 00:10:33,790 --> 00:10:35,490 where we suspect that planet 9 exists. 209 00:10:35,490 --> 00:10:37,420 But we really have no idea what it's like. 210 00:10:37,420 --> 00:10:40,420 And that means our imaginations can run wild. 211 00:10:40,430 --> 00:10:41,960 They're informed by science. 212 00:10:41,960 --> 00:10:44,290 But I love it when creativity takes hold, 213 00:10:44,300 --> 00:10:45,560 and you just run with it. 214 00:10:47,800 --> 00:10:49,470 So what are the options? 215 00:10:49,470 --> 00:10:52,400 Science suggests three possibilities. 216 00:10:52,400 --> 00:10:55,210 And the first is astonishing. 217 00:10:55,210 --> 00:10:56,870 Planet 9 could be made 218 00:10:56,880 --> 00:10:59,740 from the same materials as the Earth, 219 00:10:59,740 --> 00:11:01,910 but 10 times more massive, 220 00:11:01,910 --> 00:11:04,380 a rocky super-Earth. 221 00:11:06,620 --> 00:11:09,490 But what would this giant, rocky planet 222 00:11:09,490 --> 00:11:12,160 look like so far from the Sun? 223 00:11:12,160 --> 00:11:15,790 A bizarre volcanic world scarred with fire 224 00:11:15,790 --> 00:11:20,530 somehow emerges from the cold darkness of deep space. 225 00:11:35,080 --> 00:11:38,950 In 2016, astronomers release astonishing evidence 226 00:11:38,950 --> 00:11:41,220 of a missing ninth planet 227 00:11:41,220 --> 00:11:43,950 on the frozen edges of our solar system, 228 00:11:43,960 --> 00:11:48,260 100 billion miles from the Sun. 229 00:11:48,260 --> 00:11:50,030 Until our telescopes find it, 230 00:11:50,030 --> 00:11:54,760 we can only guess what this mysterious planet 9 is like. 231 00:11:54,770 --> 00:11:58,770 But the first option is perhaps the most surprising. 232 00:11:58,770 --> 00:12:01,970 Planet 9 could be made from rock, 233 00:12:01,970 --> 00:12:03,440 just like the Earth, 234 00:12:03,440 --> 00:12:06,240 but 10 times more massive, 235 00:12:06,240 --> 00:12:09,550 a so-called rocky super-Earth. 236 00:12:09,550 --> 00:12:11,710 When we looked out into the universe, we realized 237 00:12:11,720 --> 00:12:14,420 that the most common type of planet 238 00:12:14,420 --> 00:12:15,620 in the entire galaxy 239 00:12:15,620 --> 00:12:17,350 is something we don't have, 240 00:12:17,360 --> 00:12:19,760 something called a super-Earth. 241 00:12:22,860 --> 00:12:26,000 The Kepler space telescope finds alien worlds 242 00:12:26,000 --> 00:12:28,970 by measuring the tiny dip in light 243 00:12:28,970 --> 00:12:33,170 as a planet passes in front of its host star. 244 00:12:33,170 --> 00:12:37,610 Most of the alien solar systems Kepler finds have super-Earths. 245 00:12:37,610 --> 00:12:41,410 So how come our star doesn't have one? 246 00:12:41,410 --> 00:12:46,020 Could it be possible that planet 9 is our missing super-Earth? 247 00:12:46,020 --> 00:12:49,190 If planet 9 is a rocky super-Earth, 248 00:12:49,190 --> 00:12:51,450 what will it look like up close? 249 00:12:57,030 --> 00:13:01,160 Planetary geologist Jani Radebaugh imagines planet 9 250 00:13:01,170 --> 00:13:06,240 as a dramatic world of fire and ice. 251 00:13:06,240 --> 00:13:07,440 Right now, we're in Iceland. 252 00:13:07,440 --> 00:13:09,470 We're flying over amazing, 253 00:13:09,470 --> 00:13:12,410 beautiful volcanic landscapes of Iceland. 254 00:13:12,410 --> 00:13:14,780 We think this might be the perfect landscape 255 00:13:14,780 --> 00:13:17,850 for thinking about what might be happening on planet 9 256 00:13:17,850 --> 00:13:21,420 if it's a rocky super-Earth. 257 00:13:21,420 --> 00:13:23,550 These black mountains and lava flows 258 00:13:23,560 --> 00:13:25,690 were created by leftover heat 259 00:13:25,690 --> 00:13:29,390 from the Earth's formation spilling out onto the surface. 260 00:13:29,390 --> 00:13:33,530 Planet 9, born with so much more insulating rock, 261 00:13:33,530 --> 00:13:37,900 should have even more of this leftover heat trapped inside it. 262 00:13:37,900 --> 00:13:39,200 What we're talking about is a body 263 00:13:39,200 --> 00:13:42,140 that's maybe 10 times the mass of the Earth. 264 00:13:42,140 --> 00:13:44,270 I'd expect, because it's so large, 265 00:13:44,280 --> 00:13:46,410 that we should have lots more internal heat. 266 00:13:46,410 --> 00:13:48,680 And so, even though it's far away in the solar system, 267 00:13:48,680 --> 00:13:49,910 it's far away from the Sun, 268 00:13:49,910 --> 00:13:52,120 it's still got lots of its own energy. 269 00:13:59,160 --> 00:14:02,090 Touching down on the surface of planet 9, 270 00:14:02,090 --> 00:14:04,590 you'd find a world as inhospitable 271 00:14:04,600 --> 00:14:08,130 as you could imagine. 272 00:14:08,130 --> 00:14:10,000 Billions of miles from the Sun, 273 00:14:10,000 --> 00:14:12,500 the surface is lit by little more 274 00:14:12,500 --> 00:14:15,000 than the twinkle of distant stars 275 00:14:15,010 --> 00:14:18,740 and the red glow of intense geological activity 276 00:14:18,740 --> 00:14:21,310 on the surface. 277 00:14:21,310 --> 00:14:22,850 We can imagine, if we were on 278 00:14:22,850 --> 00:14:25,150 a super rocky Earth planet 9, 279 00:14:25,150 --> 00:14:28,050 we could have a landscape just like this one. 280 00:14:28,050 --> 00:14:30,290 There should be volcanoes erupting all the time. 281 00:14:30,290 --> 00:14:32,020 And the other thing we should see 282 00:14:32,020 --> 00:14:34,960 is lots and lots of ice and snow blanketing the landscape. 283 00:14:34,960 --> 00:14:37,930 This is because the atmosphere is so cold 284 00:14:37,930 --> 00:14:39,700 that parts of it have condensed 285 00:14:39,700 --> 00:14:41,630 and settled back down onto the surface. 286 00:14:41,630 --> 00:14:44,100 You're gonna have volcanoes. You're gonna have canyons. 287 00:14:44,100 --> 00:14:46,670 You're gonna have plate tectonics, mountain-building. 288 00:14:46,670 --> 00:14:49,470 All of these processes are still gonna be going on out there 289 00:14:49,470 --> 00:14:52,240 in what we normally would think of as the frozen, cold, 290 00:14:52,240 --> 00:14:54,740 and dead world of the outer solar system. 291 00:14:58,150 --> 00:15:00,350 As hot lava reaches the surface, 292 00:15:00,350 --> 00:15:03,550 it freezes suddenly in the cold of space, 293 00:15:03,560 --> 00:15:05,560 perhaps forming a weird, 294 00:15:05,560 --> 00:15:09,290 volcanic glass called obsidian, 295 00:15:09,290 --> 00:15:10,560 another feature shared 296 00:15:10,560 --> 00:15:13,030 with the sub-zero volcanoes of Iceland. 297 00:15:13,030 --> 00:15:15,900 Okay, let's put this whole thing together. 298 00:15:15,900 --> 00:15:18,100 We have a landscape 299 00:15:18,100 --> 00:15:20,500 that's kind of dimly lit by starlight, 300 00:15:20,510 --> 00:15:22,810 but maybe also by the reddish glow 301 00:15:22,810 --> 00:15:27,480 from erupting lavas spreading across the landscape. 302 00:15:27,480 --> 00:15:29,750 And then, behind you, you have gases 303 00:15:29,750 --> 00:15:31,310 that are changing immediately to snow 304 00:15:31,320 --> 00:15:33,820 and falling as snow down to the surface. 305 00:15:33,820 --> 00:15:37,250 And it would just be a beautiful, magical landscape. 306 00:15:40,660 --> 00:15:44,690 The case for a giant, rocky planet 9 is compelling 307 00:15:44,700 --> 00:15:46,960 because it paints such a vivid picture 308 00:15:46,970 --> 00:15:50,500 of a living volcanic world. 309 00:15:50,500 --> 00:15:51,970 But there's a problem. 310 00:15:55,540 --> 00:15:58,780 If planet 9 is, in fact, a super-Earth, 311 00:15:58,780 --> 00:16:00,840 how did it form? Where did it form? 312 00:16:00,850 --> 00:16:02,180 We don't have any other super-Earths 313 00:16:02,180 --> 00:16:03,410 in our solar system. 314 00:16:03,420 --> 00:16:05,010 And the ones we see around other stars 315 00:16:05,020 --> 00:16:07,380 are typically really close to their star. 316 00:16:07,390 --> 00:16:10,520 So how did our super-Earth end up way out there 317 00:16:10,520 --> 00:16:13,690 at the edges of our solar system? 318 00:16:13,690 --> 00:16:16,690 For planet 9 to be our rocky super-Earth, 319 00:16:16,690 --> 00:16:19,760 it would've had to have formed in the inner solar system 320 00:16:19,760 --> 00:16:22,830 and then migrated out to its current position. 321 00:16:22,830 --> 00:16:24,630 And that's a problem, 322 00:16:24,640 --> 00:16:28,070 because there probably wasn't enough rocky material left over 323 00:16:28,070 --> 00:16:29,470 in the early solar system 324 00:16:29,470 --> 00:16:33,110 to create both the massive planet 9 325 00:16:33,110 --> 00:16:37,510 as well as Mercury, Venus, Earth, and Mars. 326 00:16:37,520 --> 00:16:38,980 It's really hard to imagine 327 00:16:38,980 --> 00:16:41,820 that we could have formed a 10-Earth-mass planet here 328 00:16:41,820 --> 00:16:43,690 and still formed the rocky planets 329 00:16:43,690 --> 00:16:47,060 that we see today. 330 00:16:47,060 --> 00:16:49,260 - '- Time for a new theory. 331 00:16:49,260 --> 00:16:52,400 What if planet 9 formed from ice 332 00:16:52,400 --> 00:16:55,360 in the outer solar system? 333 00:16:55,370 --> 00:16:58,370 Calculations tell us it would have to be 10 times 334 00:16:58,370 --> 00:16:59,700 the mass of the Earth. 335 00:16:59,700 --> 00:17:01,670 And here's the kicker. 336 00:17:01,670 --> 00:17:03,870 An ice world that big 337 00:17:03,880 --> 00:17:07,940 would have an internal ocean of liquid water. 338 00:17:07,950 --> 00:17:10,110 A new world is revealed 339 00:17:10,110 --> 00:17:12,680 where icy geysers shoot through cracks 340 00:17:12,680 --> 00:17:14,280 in the frozen crust. 341 00:17:14,290 --> 00:17:15,690 And deep below it 342 00:17:15,690 --> 00:17:18,120 lies the largest body of liquid water 343 00:17:18,120 --> 00:17:19,790 in the solar system. 344 00:17:43,380 --> 00:17:45,180 The planets that make up our solar system 345 00:17:45,180 --> 00:17:48,720 seem to follow a pattern. 346 00:17:48,720 --> 00:17:53,060 The four closest to the Sun are all made from rock. 347 00:17:53,060 --> 00:17:57,830 The next four are giants made mostly from gas. 348 00:17:57,830 --> 00:18:00,660 Beyond Neptune, gas is replaced 349 00:18:00,670 --> 00:18:04,070 by multiple worlds made from ice. 350 00:18:04,070 --> 00:18:05,900 This is the Kuiper belt, 351 00:18:05,900 --> 00:18:09,170 a frozen realm of water-ice asteroids, 352 00:18:09,170 --> 00:18:11,540 millions of them. 353 00:18:11,540 --> 00:18:14,010 The Kuiper belt is a region of space 354 00:18:14,010 --> 00:18:15,880 outside of Neptune's orbit 355 00:18:15,880 --> 00:18:17,580 that extends out, 356 00:18:17,580 --> 00:18:20,420 eh, about 50 times the distance from the Earth to the Sun. 357 00:18:20,420 --> 00:18:22,290 So it's really far out there. 358 00:18:22,290 --> 00:18:24,450 And this is populated by icy bodies. 359 00:18:24,460 --> 00:18:26,790 These are giant chunks of ice 360 00:18:26,790 --> 00:18:28,790 that have some rock and other things in them. 361 00:18:28,790 --> 00:18:31,290 But they're mostly ice. 362 00:18:31,300 --> 00:18:34,700 Perhaps planet 9 is made from the same materials, 363 00:18:34,700 --> 00:18:37,430 an overgrown version of the Kuiper belt's 364 00:18:37,440 --> 00:18:40,670 most infamous citizen, Pluto. 365 00:18:43,110 --> 00:18:44,640 Poor Pluto. 366 00:18:44,640 --> 00:18:47,710 Discovered in 1930 by Clyde Tombaugh, 367 00:18:47,710 --> 00:18:49,680 this tiny ice world, 368 00:18:49,680 --> 00:18:51,180 smaller than our moon, 369 00:18:51,180 --> 00:18:54,950 was quickly proclaimed the ninth planet. 370 00:18:54,950 --> 00:18:59,320 But, in the 1990s, Mike brown and others discovered 371 00:18:59,320 --> 00:19:03,660 a host of icy worlds orbiting out with Pluto. 372 00:19:03,660 --> 00:19:07,030 Pluto was just another Kuiper belt object 373 00:19:07,030 --> 00:19:09,500 and got demoted to dwarf planet, 374 00:19:09,500 --> 00:19:12,170 to the dismay of much of the world. 375 00:19:12,170 --> 00:19:16,570 Everybody loves the idea that I killed Pluto, 376 00:19:16,570 --> 00:19:19,780 and now I'm trying to atone for my sins 377 00:19:19,780 --> 00:19:23,280 by replacing it with a new ninth planet. 378 00:19:23,280 --> 00:19:25,550 In fact, even my daughter suggested this 379 00:19:25,550 --> 00:19:28,250 long before we started looking for planet 9. 380 00:19:28,250 --> 00:19:31,420 She said, you know, "you should find a new planet." 381 00:19:31,420 --> 00:19:33,220 And then you can have found a planet. 382 00:19:33,220 --> 00:19:35,060 And there'll be nine planets again. 383 00:19:35,060 --> 00:19:37,230 "And everybody will like you again." 384 00:19:37,230 --> 00:19:41,430 If planet 9 is an icy Kuiper belt world, 385 00:19:41,430 --> 00:19:45,400 it'll be the biggest we've ever found. 386 00:19:45,400 --> 00:19:47,640 Pluto, the biggest object 387 00:19:47,640 --> 00:19:49,610 we know out there in the Kuiper belt now, 388 00:19:49,610 --> 00:19:52,170 is less than 1% the mass of the Earth, 389 00:19:52,180 --> 00:19:53,710 less than that. 390 00:19:53,710 --> 00:19:56,550 Planet 9, we think, is 10 times the mass of the Earth. 391 00:19:56,550 --> 00:19:59,920 So we're dealing with a factor of thousands of times in mass 392 00:19:59,920 --> 00:20:02,390 between the largest Kuiper belt object 393 00:20:02,390 --> 00:20:04,220 that we know now 394 00:20:04,220 --> 00:20:06,720 and the size of planet 9. 395 00:20:06,720 --> 00:20:10,790 So you're talking about super-mega-ultra-Pluto. 396 00:20:10,800 --> 00:20:12,700 It's really, really big. 397 00:20:12,700 --> 00:20:15,870 And it's hard to know what an ice ball 398 00:20:15,870 --> 00:20:18,170 like that would look like. 399 00:20:18,170 --> 00:20:22,170 It's not crazy to speculate that there could still be activity, 400 00:20:22,170 --> 00:20:23,810 internal geologic activity, 401 00:20:23,810 --> 00:20:26,410 keeping this world from being cold 402 00:20:26,410 --> 00:20:29,010 and totally dead. 403 00:20:29,010 --> 00:20:30,750 Peering through the darkness 404 00:20:30,750 --> 00:20:34,550 to a hypothetical mega-Pluto planet 9, 405 00:20:34,550 --> 00:20:37,820 we discover a giant world of ice. 406 00:20:37,820 --> 00:20:41,260 There's much less rock than a super-Earth planet 9. 407 00:20:41,260 --> 00:20:44,330 But the mass of ice alone creates enough gravity 408 00:20:44,330 --> 00:20:49,270 to generate warmth deep in the core, even out here. 409 00:20:49,270 --> 00:20:53,100 The real currency of keeping a planet alive is mass. 410 00:20:53,100 --> 00:20:56,040 Does it have enough mass to keep the interior warm? 411 00:20:56,040 --> 00:20:57,910 Well, something that's 5 to 10 times 412 00:20:57,910 --> 00:21:02,450 the mass of the Earth probably would be warm inside. 413 00:21:02,450 --> 00:21:06,680 Up close, the surface explodes with activity. 414 00:21:06,680 --> 00:21:11,550 But these volcanoes spew water ice, not lava. 415 00:21:11,560 --> 00:21:13,790 If something like a giant Pluto exists, 416 00:21:13,790 --> 00:21:15,760 it must be the most amazing landscape 417 00:21:15,760 --> 00:21:17,160 to take a walk over. 418 00:21:17,160 --> 00:21:20,630 You'd have these ice volcanoes spewing out jets 419 00:21:20,630 --> 00:21:23,630 of frozen water, of ice raining down on you. 420 00:21:23,630 --> 00:21:25,430 Maybe you'd look out over the landscape 421 00:21:25,440 --> 00:21:27,900 and see hundreds of these erupting. 422 00:21:27,910 --> 00:21:31,270 This dramatic, icy vista is a gateway 423 00:21:31,280 --> 00:21:33,080 to a secret world, 424 00:21:33,080 --> 00:21:36,110 a vast, slushy ocean of liquid water 425 00:21:36,110 --> 00:21:38,110 mixed with ice crystals, 426 00:21:38,120 --> 00:21:39,580 perhaps the largest 427 00:21:39,580 --> 00:21:42,220 single body of water in the solar system. 428 00:21:42,220 --> 00:21:44,450 There's gonna be enough internal heat, maybe, 429 00:21:44,460 --> 00:21:47,590 to turn this into a slushy water world. 430 00:21:47,590 --> 00:21:50,490 So it's not quite a terrestrial, rocky planet. 431 00:21:50,500 --> 00:21:53,000 And it's not a Uranus or Neptune. 432 00:21:53,000 --> 00:21:56,030 It's a true mega-ocean world, 433 00:21:56,030 --> 00:21:59,970 but perhaps a very cold one. 434 00:21:59,970 --> 00:22:03,540 Is planet 9 an icy mega-Pluto? 435 00:22:03,540 --> 00:22:05,470 The problem is scale. 436 00:22:05,480 --> 00:22:09,580 Pluto and the other objects in the Kuiper belt are tiny. 437 00:22:09,580 --> 00:22:12,110 So how could the same building materials 438 00:22:12,120 --> 00:22:16,220 have come together to form a giant? 439 00:22:16,220 --> 00:22:18,150 So, the idea that planet 9 440 00:22:18,160 --> 00:22:22,560 is simply a really scaled-up Pluto, a mega-Pluto, 441 00:22:22,560 --> 00:22:24,230 has some difficulties. 442 00:22:24,230 --> 00:22:27,930 We just don't think that there was enough mass out there 443 00:22:27,930 --> 00:22:29,800 in the far reaches of the solar system 444 00:22:29,800 --> 00:22:32,230 to all come together to build a planet that large. 445 00:22:32,240 --> 00:22:34,240 When you look at the Kuiper belt, 446 00:22:34,240 --> 00:22:36,140 there are all of these small, icy bodies. 447 00:22:36,140 --> 00:22:38,170 There's nothing very big out there. 448 00:22:38,180 --> 00:22:40,240 And we think that's not a coincidence, 449 00:22:40,240 --> 00:22:42,480 that the disk of dust and gas that formed the planets 450 00:22:42,480 --> 00:22:44,680 had more stuff closer to the Sun. 451 00:22:44,680 --> 00:22:46,620 And by the time you got out to where Pluto is, 452 00:22:46,620 --> 00:22:49,350 there wasn't much material to build planets out of, 453 00:22:49,350 --> 00:22:50,690 certainly not a planet 454 00:22:50,690 --> 00:22:55,090 5 to 10 times the mass of the Earth. 455 00:22:55,090 --> 00:22:59,760 So, if planet 9 didn't form in the icy outer system 456 00:22:59,760 --> 00:23:03,430 and didn't form in the rocky, inner solar system, 457 00:23:03,430 --> 00:23:05,370 where did it come from? 458 00:23:05,370 --> 00:23:07,400 The more likely option, 459 00:23:07,410 --> 00:23:10,410 planet 9 formed in the gas-rich zone 460 00:23:10,410 --> 00:23:12,540 in the middle of our solar system 461 00:23:12,540 --> 00:23:16,850 that also created Jupiter, Saturn, and Neptune. 462 00:23:16,850 --> 00:23:19,920 A gassy planet 9 could be similar to Neptune, 463 00:23:19,920 --> 00:23:23,390 but perhaps a little smaller, 464 00:23:23,390 --> 00:23:25,320 a mini-Neptune. 465 00:23:25,320 --> 00:23:27,960 But how would it get so much farther out 466 00:23:27,960 --> 00:23:29,860 than the other gas giants? 467 00:23:29,860 --> 00:23:32,830 And what would it look like? 468 00:23:32,830 --> 00:23:36,100 Imagine a weird, translucent world 469 00:23:36,100 --> 00:23:40,300 glowing in the dark like a giant deep-sea creature. 470 00:23:57,960 --> 00:24:00,420 Something on the fringes of our solar system 471 00:24:00,420 --> 00:24:03,890 is upsetting orbits and causing a ruckus. 472 00:24:03,900 --> 00:24:06,730 Could it be a planet? 473 00:24:06,730 --> 00:24:08,860 It's incredible to me that we now know 474 00:24:08,870 --> 00:24:10,500 of thousands of other planets 475 00:24:10,500 --> 00:24:12,570 going around other stars in the sky, 476 00:24:12,570 --> 00:24:15,370 but we may have missed a big planet 477 00:24:15,370 --> 00:24:17,510 in our own solar system. 478 00:24:17,510 --> 00:24:21,240 Planet 9, a world we know almost nothing about, 479 00:24:21,250 --> 00:24:25,250 beyond the possibility that it exists. 480 00:24:25,250 --> 00:24:29,990 Science suggests intriguing options... 481 00:24:29,990 --> 00:24:33,420 a giant, rocky world with a heart of fire, 482 00:24:33,420 --> 00:24:36,090 or an ice world filled 483 00:24:36,090 --> 00:24:39,130 with a giant, slushy ocean. 484 00:24:39,130 --> 00:24:43,530 But problems with each theory have led to new hunches. 485 00:24:43,530 --> 00:24:46,540 So, if it's not a rocky, metallic super-Earth 486 00:24:46,540 --> 00:24:50,740 and it's not a gigantic, ice-ball, mega-Pluto, 487 00:24:50,740 --> 00:24:52,240 what's left? 488 00:24:52,240 --> 00:24:54,910 And the answer is a gas giant. 489 00:24:54,910 --> 00:24:59,150 And that strikes me as being the most likely prospect. 490 00:24:59,150 --> 00:25:02,350 When you think about the mass of planet 9 491 00:25:02,350 --> 00:25:05,220 and where it is now, my best guess, 492 00:25:05,220 --> 00:25:10,030 it's something like a miniature version of Neptune. 493 00:25:10,030 --> 00:25:11,960 The gas giant planets 494 00:25:11,960 --> 00:25:14,960 are the monsters of our solar system. 495 00:25:14,970 --> 00:25:17,430 Instead of a solid surface, like the Earth, 496 00:25:17,440 --> 00:25:20,970 the gas giants have thick, stormy atmospheres 497 00:25:20,970 --> 00:25:24,110 that descend for tens of thousands of miles, 498 00:25:24,110 --> 00:25:26,980 shrouding their small, rocky cores. 499 00:25:29,180 --> 00:25:31,710 Jupiter is the largest gas giant, 500 00:25:31,720 --> 00:25:35,380 over 300 times the mass of Earth. 501 00:25:35,390 --> 00:25:36,690 Moving out from Jupiter, 502 00:25:36,690 --> 00:25:40,220 the gas giants get progressively smaller, 503 00:25:40,220 --> 00:25:44,190 Saturn, then Uranus, and finally Neptune, 504 00:25:44,200 --> 00:25:48,060 around 17 times the mass of the Earth. 505 00:25:48,070 --> 00:25:50,930 If planet 9 is a gas giant, 506 00:25:50,940 --> 00:25:53,000 it'll be even smaller, 507 00:25:53,000 --> 00:25:55,170 a mini-Neptune. 508 00:25:55,170 --> 00:25:57,370 If planet 9 is a mini-Neptune, 509 00:25:57,380 --> 00:25:59,210 if it's a lot like Neptune, 510 00:25:59,210 --> 00:26:01,040 then it's not really like 511 00:26:01,050 --> 00:26:02,580 a terrestrial planet, like Earth. 512 00:26:02,580 --> 00:26:05,150 But it's not really like a gas giant, like Jupiter. 513 00:26:05,150 --> 00:26:07,480 Neptune is this weird, in-between thing 514 00:26:07,490 --> 00:26:09,890 where it's probably got a rocky core. 515 00:26:09,890 --> 00:26:12,790 But it's actually, mostly, what astronomers call ices. 516 00:26:12,790 --> 00:26:16,430 It's got methane in it and water and various other substances 517 00:26:16,430 --> 00:26:19,560 and a very, very, very thick atmosphere on top of that. 518 00:26:24,070 --> 00:26:26,800 Neptune's thick clouds are stained blue 519 00:26:26,800 --> 00:26:28,940 with molecules of methane. 520 00:26:28,940 --> 00:26:33,610 But planet 9's atmosphere could be transparent. 521 00:26:33,610 --> 00:26:36,650 It's so cold out there, you're getting almost 522 00:26:36,650 --> 00:26:38,750 no extra energy from the Sun. 523 00:26:38,750 --> 00:26:40,650 And so then anything heavy in the atmosphere, 524 00:26:40,650 --> 00:26:42,720 any heavier molecule, over time, 525 00:26:42,720 --> 00:26:44,790 would have probably fallen to the surface. 526 00:26:44,790 --> 00:26:46,720 And only the lightest elements, 527 00:26:46,720 --> 00:26:49,690 the lightest molecules, would stay in your atmosphere, 528 00:26:49,690 --> 00:26:52,860 so maybe just almost pure hydrogen or helium. 529 00:26:52,860 --> 00:26:56,230 And you'd have, maybe, a really clear atmosphere. 530 00:26:56,230 --> 00:26:58,300 What would a mini-Neptune look like 531 00:26:58,300 --> 00:27:00,000 that far out from the Sun? 532 00:27:00,000 --> 00:27:02,600 The thing I think of are things like jellyfish, right? 533 00:27:02,610 --> 00:27:04,340 That sort of beautiful, translucent look, 534 00:27:04,340 --> 00:27:07,710 where you're looking through to the innards of the organism. 535 00:27:07,710 --> 00:27:09,180 In this case, you might look through 536 00:27:09,180 --> 00:27:12,610 to the innards of the planet in some way. 537 00:27:12,620 --> 00:27:15,180 The atmosphere may be transparent. 538 00:27:15,190 --> 00:27:17,890 But this planet is far from calm. 539 00:27:17,890 --> 00:27:21,420 The interior is lit by the flash of thunderstorms. 540 00:27:21,430 --> 00:27:24,090 And faint lights dance around the poles 541 00:27:24,100 --> 00:27:26,700 as solar winds from distant stars 542 00:27:26,700 --> 00:27:29,670 stream down the planet's magnetic fields. 543 00:27:29,670 --> 00:27:31,700 Looking into the innards of the planet, 544 00:27:31,700 --> 00:27:34,300 it would look, in some ways, like these gorgeous, 545 00:27:34,310 --> 00:27:38,310 beautiful deep-sea organisms that are bioluminescent. 546 00:27:38,310 --> 00:27:40,280 And we may have the planetary equivalent 547 00:27:40,280 --> 00:27:43,080 of something like out there in the inky blackness of space, 548 00:27:43,080 --> 00:27:47,450 rather than the inky blackness of the deep ocean. 549 00:27:47,450 --> 00:27:50,550 Could planet 9 be a mini-Neptune? 550 00:27:50,550 --> 00:27:54,160 Surprisingly, the possibility of an extra gas giant 551 00:27:54,160 --> 00:27:57,260 in our solar system isn't new. 552 00:27:57,260 --> 00:27:59,860 In 2011, scientists attempted 553 00:27:59,860 --> 00:28:01,130 to replicate the formation 554 00:28:01,130 --> 00:28:04,500 of our solar system using supercomputers. 555 00:28:04,500 --> 00:28:06,570 But their models didn't work 556 00:28:06,570 --> 00:28:12,040 unless they added an extra gas giant planet to the mix. 557 00:28:12,040 --> 00:28:14,240 It was really difficult to reproduce 558 00:28:14,250 --> 00:28:16,350 our current solar system. 559 00:28:16,350 --> 00:28:18,150 But one scientist found that, 560 00:28:18,150 --> 00:28:21,020 if you add a fifth large planet 561 00:28:21,020 --> 00:28:22,420 to our solar system, 562 00:28:22,420 --> 00:28:25,090 then that planet will end up 563 00:28:25,090 --> 00:28:27,320 getting ejected from our solar system. 564 00:28:27,320 --> 00:28:30,260 And you'd have the planets that we have today. 565 00:28:32,200 --> 00:28:34,630 Is planet 9 the missing gas giant 566 00:28:34,630 --> 00:28:37,370 predicted by the supercomputers? 567 00:28:37,370 --> 00:28:39,670 The computer model shows it being ejected 568 00:28:39,670 --> 00:28:42,100 by the immense gravity of Jupiter. 569 00:28:42,110 --> 00:28:46,440 But did planet 9 instead cling to our solar system 570 00:28:46,440 --> 00:28:50,150 by the tips of its gravitational fingers? 571 00:28:50,150 --> 00:28:51,850 Sometimes, our mathematical models 572 00:28:51,850 --> 00:28:53,750 predict things that we think are impossible. 573 00:28:53,750 --> 00:28:55,320 And then we find them. 574 00:28:55,320 --> 00:28:56,990 And, for a while, we've known that, 575 00:28:56,990 --> 00:28:58,490 if you throw a mini-Neptune 576 00:28:58,490 --> 00:29:00,620 into the mix of planets forming, 577 00:29:00,620 --> 00:29:02,160 the models work better. 578 00:29:02,160 --> 00:29:06,030 Maybe we found that key, finally... planet 9. 579 00:29:06,030 --> 00:29:09,200 We know giant planets can get thrown around. 580 00:29:09,200 --> 00:29:11,830 Observers have even seen ejected planets 581 00:29:11,840 --> 00:29:15,500 floating free in the space between stars. 582 00:29:15,510 --> 00:29:19,610 Did planet 9 almost suffer the same fate? 583 00:29:19,610 --> 00:29:22,280 It's entirely possible that there could've been 584 00:29:22,280 --> 00:29:23,710 a planet forming bigger than Earth, 585 00:29:23,710 --> 00:29:25,750 something like a super-Earth, well on its way 586 00:29:25,750 --> 00:29:27,280 to becoming a gas giant 587 00:29:27,280 --> 00:29:30,320 in this wonderful area of the disk, 588 00:29:30,320 --> 00:29:32,090 where it could've drawn in a lot of material 589 00:29:32,090 --> 00:29:34,160 and become a gas giant like Jupiter, 590 00:29:34,160 --> 00:29:36,530 except it got too close to Jupiter. 591 00:29:36,530 --> 00:29:38,060 And, before it could do that, 592 00:29:38,060 --> 00:29:40,360 it was gravitationally thrown away 593 00:29:40,360 --> 00:29:42,700 from this wonderful feeding ground 594 00:29:42,700 --> 00:29:44,570 out into the much sparser, 595 00:29:44,570 --> 00:29:47,470 more barren desert of the outer solar system. 596 00:29:50,440 --> 00:29:53,840 Is planet 9 really a frozen mini-Neptune 597 00:29:53,840 --> 00:29:57,310 banished to the badlands of the outer solar system? 598 00:29:57,310 --> 00:30:00,020 Right now, it's our best bet. 599 00:30:00,020 --> 00:30:02,750 But there is one more option. 600 00:30:02,750 --> 00:30:04,590 Some scientists believe 601 00:30:04,590 --> 00:30:08,420 planet 9 may not have formed around our Sun at all. 602 00:30:11,800 --> 00:30:14,030 Is our most distant planet 603 00:30:14,030 --> 00:30:17,600 an alien world snatched from another star? 604 00:30:37,590 --> 00:30:40,390 If the mysterious planet 9 exists, 605 00:30:40,390 --> 00:30:42,920 it is by far the most distant planet 606 00:30:42,930 --> 00:30:44,330 in the solar system, 607 00:30:44,330 --> 00:30:47,200 20 times farther out than Neptune. 608 00:30:47,200 --> 00:30:49,770 So how did it get there? 609 00:30:49,770 --> 00:30:53,540 Was it made in the place it currently occupies? 610 00:30:53,540 --> 00:30:56,170 Or was it flung out from the inner solar system 611 00:30:56,170 --> 00:30:57,710 as a rocky super-Earth 612 00:30:57,710 --> 00:31:01,180 or, more likely, a mini-Neptune? 613 00:31:01,180 --> 00:31:02,880 The jury's out. 614 00:31:02,880 --> 00:31:05,810 But there is another option. 615 00:31:05,820 --> 00:31:07,620 And it's out of this world. 616 00:31:07,620 --> 00:31:10,350 So the question is, then, where did it come from 617 00:31:10,350 --> 00:31:11,820 if neither of these things is right? 618 00:31:11,820 --> 00:31:15,390 And it's possible that there is another explanation. 619 00:31:15,390 --> 00:31:19,260 And that is that planet 9 is an alien visitor 620 00:31:19,260 --> 00:31:21,100 from outer space. 621 00:31:24,070 --> 00:31:27,540 The Sun is just 1 of 200 billion stars 622 00:31:27,540 --> 00:31:30,210 orbiting the supermassive black hole 623 00:31:30,210 --> 00:31:33,310 at the center of the milky way galaxy. 624 00:31:33,310 --> 00:31:36,780 Most of these stars probably have multiple planets. 625 00:31:36,780 --> 00:31:40,350 And scientists now believe that, from time to time, 626 00:31:40,350 --> 00:31:44,350 two stars might pass a little too close for comfort. 627 00:31:44,360 --> 00:31:48,820 The result... planetary theft. 628 00:31:48,830 --> 00:31:51,060 We know that the Sun moves around in the galaxy. 629 00:31:51,060 --> 00:31:52,660 We know that there are other stars 630 00:31:52,660 --> 00:31:53,860 and other solar systems. 631 00:31:53,860 --> 00:31:56,600 Is it possible that the Sun passed so close 632 00:31:56,600 --> 00:31:57,900 to another solar system 633 00:31:57,900 --> 00:32:01,470 that it stole a planet? 634 00:32:01,470 --> 00:32:04,370 Today, our Sun drifts through space alone, 635 00:32:04,380 --> 00:32:07,340 like a yacht in the open ocean. 636 00:32:07,340 --> 00:32:09,680 But that wasn't always the case. 637 00:32:09,680 --> 00:32:12,950 Rewind the clock 4.6 billion years, 638 00:32:12,950 --> 00:32:17,220 and our local star cluster was a much more crowded place, 639 00:32:17,220 --> 00:32:21,120 ideal conditions for planet 9 to jump ship. 640 00:32:23,160 --> 00:32:25,030 The Sun was born in a nursery 641 00:32:25,030 --> 00:32:27,130 with thousands of other stars. 642 00:32:27,130 --> 00:32:29,000 Just like the boats in this harbor, 643 00:32:29,000 --> 00:32:32,170 there are so many boats around, so many neighbors. 644 00:32:32,170 --> 00:32:34,100 It was like that for the young Sun. 645 00:32:36,070 --> 00:32:39,540 Stars like the Sun are born in stellar nurseries, 646 00:32:39,540 --> 00:32:41,940 vast clouds of gas that collapse 647 00:32:41,950 --> 00:32:44,880 to form tens of thousands of stars, 648 00:32:44,880 --> 00:32:47,250 all tightly packed together. 649 00:32:49,250 --> 00:32:51,350 Astronomers think it's possible 650 00:32:51,360 --> 00:32:55,560 that, inside this cramped, confused playground of stars, 651 00:32:55,560 --> 00:32:58,830 our Sun's gravity could've stolen planet 9 652 00:32:58,830 --> 00:33:00,800 from a passing neighbor. 653 00:33:00,800 --> 00:33:02,530 Imagine this cool scenario. 654 00:33:02,530 --> 00:33:04,530 You've got an alien star. 655 00:33:04,540 --> 00:33:06,700 And around that star forms a planet. 656 00:33:06,700 --> 00:33:08,100 This is planet 9. 657 00:33:08,110 --> 00:33:10,170 And here comes the Sun whizzing by. 658 00:33:10,170 --> 00:33:12,940 The Sun gets so close that it steals planet 9 659 00:33:12,940 --> 00:33:16,650 on its way out into the galaxy. 660 00:33:16,650 --> 00:33:18,950 It sounds like science fiction. 661 00:33:18,950 --> 00:33:23,080 But our Sun may already have a criminal record. 662 00:33:23,090 --> 00:33:26,420 There's some evidence that the comets in our solar system 663 00:33:26,420 --> 00:33:28,520 may not have started in our solar system. 664 00:33:28,530 --> 00:33:31,690 We may have stolen comets from other stars. 665 00:33:31,700 --> 00:33:33,230 If that's the case, 666 00:33:33,230 --> 00:33:34,860 it's not totally outrageous 667 00:33:34,870 --> 00:33:38,700 to think that a planet that formed around another star 668 00:33:38,700 --> 00:33:41,500 somehow made its way into our solar system 669 00:33:41,510 --> 00:33:45,010 and became part of our family. 670 00:33:45,010 --> 00:33:47,810 But if planet 9 really did come from another star, 671 00:33:47,810 --> 00:33:51,280 how will we know for sure that it's an alien visitor? 672 00:33:51,280 --> 00:33:53,250 What we'd like to do is essentially 673 00:33:53,250 --> 00:33:55,650 a DNA test on planet 9, 674 00:33:55,650 --> 00:33:57,620 scoop up some of its surface 675 00:33:57,620 --> 00:34:01,620 and look for material that we absolutely know 676 00:34:01,630 --> 00:34:03,330 couldn't have formed around our Sun, 677 00:34:03,330 --> 00:34:05,730 because we don't see it anywhere else in our solar system. 678 00:34:05,730 --> 00:34:07,660 We may even have to send a probe there 679 00:34:07,660 --> 00:34:09,400 to really get a good look at it 680 00:34:09,400 --> 00:34:11,700 and find out what its chemical composition is, 681 00:34:11,700 --> 00:34:14,740 exactly everything we can find out about its orbit. 682 00:34:14,740 --> 00:34:16,170 And, that way, we might be able to see 683 00:34:16,170 --> 00:34:19,070 if there are any sort of fingerprints, 684 00:34:19,080 --> 00:34:21,240 smoking-gun pieces of evidence 685 00:34:21,250 --> 00:34:24,210 that'll say clearly this formed here 686 00:34:24,210 --> 00:34:26,550 or it formed out there. 687 00:34:30,220 --> 00:34:34,390 Unfortunately, before we can 688 00:34:34,390 --> 00:34:38,190 we first have to find it. 689 00:34:38,200 --> 00:34:39,660 Astronomers like Mike brown 690 00:34:39,660 --> 00:34:41,860 have made the challenge a little easier, 691 00:34:41,870 --> 00:34:45,400 using math to narrow down the zone. 692 00:34:45,400 --> 00:34:47,840 What we know right now is that planet 9 693 00:34:47,840 --> 00:34:50,970 is in a swath of the sky that goes about like this. 694 00:34:50,970 --> 00:34:53,310 It's about this big. It goes across like this. 695 00:34:53,310 --> 00:34:55,580 But we think we even know a little bit better. 696 00:34:55,580 --> 00:34:57,980 We've pinpointed, or at least slightly constrained 697 00:34:57,980 --> 00:35:01,580 where it is, to a patch of sky that's about this big. 698 00:35:01,590 --> 00:35:03,320 It's still a lot of sky to look at. 699 00:35:03,320 --> 00:35:07,420 But it's a lot less than having to look at the whole sky. 700 00:35:07,420 --> 00:35:12,090 Mike's patch of sky is close 701 00:35:12,100 --> 00:35:13,530 he's going to wait until fall, 702 00:35:13,530 --> 00:35:15,460 when Orion is highest in the sky, 703 00:35:15,470 --> 00:35:17,300 to search for planet 9 704 00:35:17,300 --> 00:35:22,100 using the Subaru infrared telescope on Hawaii. 705 00:35:22,110 --> 00:35:23,610 The telescope is fine-tuned 706 00:35:23,610 --> 00:35:25,670 to pick out the faint heat signature 707 00:35:25,680 --> 00:35:27,280 of distant objects 708 00:35:27,280 --> 00:35:30,850 against the cold backdrop of deep space. 709 00:35:30,850 --> 00:35:33,180 Planet 9 may be frozen. 710 00:35:33,180 --> 00:35:35,120 But it will be warmer than space. 711 00:35:35,120 --> 00:35:37,450 And that tiny difference in temperature 712 00:35:37,450 --> 00:35:40,590 is all this incredible telescope needs. 713 00:35:40,590 --> 00:35:42,760 We want to see two pictures taken 714 00:35:42,760 --> 00:35:45,390 of the same area of the sky a few weeks apart. 715 00:35:45,400 --> 00:35:47,030 The stars don't move. 716 00:35:47,030 --> 00:35:49,330 But you see this one, little thing going, "boop, boop, boop," 717 00:35:49,330 --> 00:35:51,070 as you flash the pictures back and forth. 718 00:35:51,070 --> 00:35:52,870 That's what happens when you have an object 719 00:35:52,870 --> 00:35:54,540 moving around the Sun 720 00:35:54,540 --> 00:35:56,270 against the background of stars. 721 00:35:56,270 --> 00:35:58,210 That's how Pluto was discovered. 722 00:35:58,210 --> 00:36:01,080 That's how we're gonna find planet 9 if it exists. 723 00:36:03,250 --> 00:36:05,850 It could take years to find planet 9. 724 00:36:05,850 --> 00:36:07,920 But when we do spot it, 725 00:36:07,920 --> 00:36:11,120 scientists will be able to analyze its light. 726 00:36:11,120 --> 00:36:13,520 And hidden within that faint glow 727 00:36:13,520 --> 00:36:15,460 could be the chemical signature 728 00:36:15,460 --> 00:36:18,690 for rock, ice, or gas. 729 00:36:18,700 --> 00:36:21,600 If it is, planet 9's identity 730 00:36:21,600 --> 00:36:25,630 will finally be revealed. 731 00:36:25,640 --> 00:36:28,840 What lies in store beyond that is a mystery. 732 00:36:28,840 --> 00:36:32,010 But perhaps the most exciting prospect 733 00:36:32,010 --> 00:36:37,210 is planet 9 could be home to a family of moons. 734 00:36:37,210 --> 00:36:40,050 And it's just possible one of these moons 735 00:36:40,050 --> 00:36:42,250 could provide a home for life 736 00:36:42,250 --> 00:36:45,350 100 billion miles from the Sun. 737 00:37:04,980 --> 00:37:07,380 Are we alone in the universe? 738 00:37:10,010 --> 00:37:12,450 For decades, scientists have scoured 739 00:37:12,450 --> 00:37:14,320 our closest planetary neighbor 740 00:37:14,320 --> 00:37:17,090 for signs of extraterrestrial life. 741 00:37:19,090 --> 00:37:22,060 But so far, not a trace has been found. 742 00:37:26,130 --> 00:37:29,430 Is it possible we're targeting the wrong planet? 743 00:37:33,370 --> 00:37:35,370 If planet 9 is real, 744 00:37:35,370 --> 00:37:38,970 it sits on the icy outer limits of the solar system. 745 00:37:38,980 --> 00:37:43,140 But even here, 100 billion miles from the Sun, 746 00:37:43,150 --> 00:37:46,480 it's just possible that life could thrive 747 00:37:46,480 --> 00:37:48,720 not on the planet itself, 748 00:37:48,720 --> 00:37:51,520 but deep inside its moons. 749 00:37:51,520 --> 00:37:53,860 Historically, we've always thought of moons 750 00:37:53,860 --> 00:37:56,190 as being these little, insignificant places. 751 00:37:56,190 --> 00:37:57,860 But the incredible thing is they may be 752 00:37:57,860 --> 00:37:59,990 the best places to find life. 753 00:38:00,000 --> 00:38:01,560 In our solar system alone, 754 00:38:01,570 --> 00:38:04,130 there may be far more chances for life on moons of planets 755 00:38:04,130 --> 00:38:06,600 than there are on planets themselves. 756 00:38:08,640 --> 00:38:11,110 Moons excite astrobiologists 757 00:38:11,110 --> 00:38:14,810 because they can sometimes support liquid water, 758 00:38:14,810 --> 00:38:17,480 no matter how far they sit from the Sun. 759 00:38:17,480 --> 00:38:20,750 The key is something called tidal heating. 760 00:38:23,450 --> 00:38:26,390 Moons on elliptical orbits get squashed 761 00:38:26,390 --> 00:38:29,860 and squeezed by the gravity of their parent planet. 762 00:38:29,860 --> 00:38:32,260 This generates heat and melts ice 763 00:38:32,260 --> 00:38:36,130 to form underground oceans of liquid water, 764 00:38:36,130 --> 00:38:40,700 the key ingredient for life as we know it. 765 00:38:40,700 --> 00:38:43,970 If planet 9 is as big as scientists predict, 766 00:38:43,970 --> 00:38:46,310 it could have multiple moons. 767 00:38:46,310 --> 00:38:48,680 And maybe one of those moons 768 00:38:48,680 --> 00:38:51,210 could have warm, salty oceans 769 00:38:51,210 --> 00:38:54,380 primed for simple life. 770 00:38:54,380 --> 00:38:56,280 So, if you have planet 9, 771 00:38:56,290 --> 00:38:58,120 and it's got icy moons, and these icy moons 772 00:38:58,120 --> 00:39:00,290 are on the right kinds of orbits, 773 00:39:00,290 --> 00:39:03,360 the heat could be coming from within, not without. 774 00:39:03,360 --> 00:39:06,190 And so the Sun basically doesn't matter. 775 00:39:06,200 --> 00:39:09,700 You could have liquid water below the surface 776 00:39:09,700 --> 00:39:11,930 that's heated from the internal geology. 777 00:39:11,940 --> 00:39:13,740 You could have geysers of water 778 00:39:13,740 --> 00:39:15,200 like what we see coming off of moons 779 00:39:15,210 --> 00:39:16,810 around Saturn and Jupiter. 780 00:39:16,810 --> 00:39:19,170 You could have that all the way out there at planet 9. 781 00:39:22,850 --> 00:39:27,980 Imagine planet 9 with a system of giant moons. 782 00:39:27,980 --> 00:39:30,790 The closest moon is heated to melting point 783 00:39:30,790 --> 00:39:34,020 by planet 9's immense gravity. 784 00:39:34,020 --> 00:39:35,560 There's no life here. 785 00:39:35,560 --> 00:39:38,490 Any water boiled away millions of years ago, 786 00:39:38,500 --> 00:39:41,430 creating a hot, arid ball of rock. 787 00:39:44,430 --> 00:39:47,100 Farther out lies a second giant moon. 788 00:39:47,100 --> 00:39:51,540 This new world is encased in bright, white water ice. 789 00:39:54,180 --> 00:39:56,240 But the crust hides a secret... 790 00:39:56,250 --> 00:39:59,250 a vast ocean of warm liquid water 791 00:39:59,250 --> 00:40:02,480 heated by volcanic vents on the ocean floor. 792 00:40:04,720 --> 00:40:08,120 This hidden world is rich with organic chemistry. 793 00:40:08,120 --> 00:40:13,030 And it could even support a weird, alien zoo 794 00:40:13,030 --> 00:40:16,100 of pale aquatic creatures. 795 00:40:16,100 --> 00:40:18,400 We associate life with the Sun. 796 00:40:18,400 --> 00:40:20,970 That's how we think of life originating on the Earth. 797 00:40:20,970 --> 00:40:22,600 But we know you don't need the Sun. 798 00:40:22,610 --> 00:40:25,170 We have tube worms at the bottom of the ocean 799 00:40:25,180 --> 00:40:27,180 which live off of hydrothermal vents. 800 00:40:27,180 --> 00:40:29,240 They get all the chemicals and the heat they need 801 00:40:29,250 --> 00:40:31,550 from, basically, the interior of the Earth. 802 00:40:31,550 --> 00:40:33,820 This is not out of the question. You know, decades ago, 803 00:40:33,820 --> 00:40:35,820 you'd have been laughed out of a lecture hall 804 00:40:35,820 --> 00:40:37,820 if you'd have said something like that. 805 00:40:37,820 --> 00:40:39,890 But we have learned so much about life 806 00:40:39,890 --> 00:40:41,220 in extreme environments since then 807 00:40:41,220 --> 00:40:43,520 that this is now in the realm of possibility, 808 00:40:43,530 --> 00:40:45,090 talking about life on a planet 809 00:40:45,100 --> 00:40:47,100 beyond Pluto in our own solar system. 810 00:40:47,100 --> 00:40:48,700 Wherever there's energy, 811 00:40:48,700 --> 00:40:50,700 wherever there's heat, there can be life, 812 00:40:50,700 --> 00:40:54,070 even all the way out by planet 9. 813 00:40:54,070 --> 00:40:55,570 There is good news. 814 00:40:55,570 --> 00:40:58,570 If planet 9 does have an active watery moon, 815 00:40:58,580 --> 00:41:01,210 we should be able to see it with our telescopes. 816 00:41:03,550 --> 00:41:05,580 The active moons of Jupiter and Saturn 817 00:41:05,580 --> 00:41:07,880 are the brightest in the night sky, 818 00:41:07,880 --> 00:41:11,620 thanks to warm water gushing out from cracks in the surface 819 00:41:11,620 --> 00:41:16,960 and freezing in bright white layers of fresh ice. 820 00:41:16,960 --> 00:41:19,890 If planet 9's moons have liquid oceans, 821 00:41:19,900 --> 00:41:23,100 their surfaces should be just as bright. 822 00:41:30,570 --> 00:41:34,340 The race is on to image planet 9 and its moons. 823 00:41:34,340 --> 00:41:37,850 But what we'll see when those pictures come back 824 00:41:37,850 --> 00:41:39,380 is anybody's guess. 825 00:41:39,380 --> 00:41:41,480 I have to admit, there's some wonderful tension 826 00:41:41,480 --> 00:41:44,290 that I feel right now when it comes to finding planet 9. 827 00:41:44,290 --> 00:41:45,850 We have giant telescopes 828 00:41:45,860 --> 00:41:48,120 that are scanning the sky looking for it. 829 00:41:48,120 --> 00:41:51,560 So, any day now, I'm waiting with baited breath. 830 00:41:51,560 --> 00:41:52,790 My daughter believes 831 00:41:52,800 --> 00:41:56,100 that planet 9 is pink with purple dots. 832 00:41:56,100 --> 00:41:58,900 Um, she might be right. 833 00:42:03,340 --> 00:42:04,740 One thing's for sure. 834 00:42:04,740 --> 00:42:07,980 If and when we do find planet 9, 835 00:42:07,980 --> 00:42:12,150 we'll never look at our solar system the same way again. 836 00:42:12,150 --> 00:42:13,850 This is tremendously exciting, 837 00:42:13,850 --> 00:42:16,050 because, if it's there, it's already telling us 838 00:42:16,050 --> 00:42:20,690 that there's more to know about our solar system, 839 00:42:20,690 --> 00:42:23,690 that there are more secrets literally under the Sun 840 00:42:23,690 --> 00:42:26,160 than we have dreamed of in our philosophy. 65155

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