1 00:00:01,008 --> 00:00:04,341 I'm going to tell you a story from 200 years ago. 2 00:00:04,785 --> 00:00:08,039 In 1820, French astronomer Alexis Bouvard 3 00:00:08,063 --> 00:00:12,895 almost became the second person in human history to discover a planet. 4 00:00:13,330 --> 00:00:16,648 He'd been tracking the position of Uranus across the night sky 5 00:00:16,672 --> 00:00:18,406 using old star catalogs, 6 00:00:18,430 --> 00:00:20,728 and it didn't quite go around the Sun 7 00:00:20,752 --> 00:00:23,172 the way that his predictions said it should. 8 00:00:23,196 --> 00:00:25,299 Sometimes it was a little too fast, 9 00:00:25,323 --> 00:00:27,006 sometimes it was a little too slow. 10 00:00:27,030 --> 00:00:30,258 Bouvard knew that his predictions were perfect. 11 00:00:30,778 --> 00:00:34,072 So it had to be that those old star catalogs were bad. 12 00:00:34,096 --> 00:00:36,158 He told astronomers of the day, 13 00:00:36,182 --> 00:00:37,849 "Do better measurements." 14 00:00:38,620 --> 00:00:39,778 So they did. 15 00:00:39,802 --> 00:00:42,047 Astronomers spent the next two decades 16 00:00:42,071 --> 00:00:46,142 meticulously tracking the position of Uranus across the sky, 17 00:00:46,166 --> 00:00:49,841 but it still didn't fit Bouvard's predictions. 18 00:00:49,865 --> 00:00:52,017 By 1840, it had become obvious. 19 00:00:52,041 --> 00:00:55,093 The problem was not with those old star catalogs, 20 00:00:55,117 --> 00:00:57,584 the problem was with the predictions. 21 00:00:57,998 --> 00:00:59,537 And astronomers knew why. 22 00:00:59,561 --> 00:01:03,736 They realized that there must be a distant, giant planet 23 00:01:03,760 --> 00:01:05,416 just beyond the orbit of Uranus 24 00:01:05,440 --> 00:01:07,275 that was tugging along at that orbit, 25 00:01:07,299 --> 00:01:09,871 sometimes pulling it along a bit too fast, 26 00:01:09,895 --> 00:01:11,561 sometimes holding it back. 27 00:01:12,768 --> 00:01:14,776 Must have been frustrating back in 1840 28 00:01:14,800 --> 00:01:18,179 to see these gravitational effects of this distant, giant planet 29 00:01:18,203 --> 00:01:21,361 but not yet know how to actually find it. 30 00:01:21,996 --> 00:01:24,068 Trust me, it's really frustrating. 31 00:01:24,092 --> 00:01:25,552 (Laughter) 32 00:01:25,576 --> 00:01:27,828 But in 1846, another French astronomer, 33 00:01:27,852 --> 00:01:29,133 Urbain Le Verrier, 34 00:01:29,157 --> 00:01:30,329 worked through the math 35 00:01:30,353 --> 00:01:33,069 and figured out how to predict the location of the planet. 36 00:01:33,093 --> 00:01:36,193 He sent his prediction to the Berlin observatory, 37 00:01:36,217 --> 00:01:37,662 they opened up their telescope 38 00:01:37,686 --> 00:01:40,741 and in the very first night they found this faint point of light 39 00:01:40,765 --> 00:01:44,044 slowly moving across the sky and discovered Neptune. 40 00:01:44,068 --> 00:01:48,294 It was this close on the sky to Le Verrier's predicted location. 41 00:01:49,862 --> 00:01:54,410 The story of prediction and discrepancy and new theory 42 00:01:54,434 --> 00:01:57,388 and triumphant discoveries is so classic 43 00:01:57,412 --> 00:02:00,403 and Le Verrier became so famous from it, 44 00:02:00,427 --> 00:02:03,141 that people tried to get in on the act right away. 45 00:02:03,165 --> 00:02:05,680 In the last 163 years, 46 00:02:05,704 --> 00:02:11,319 dozens of astronomers have used some sort of alleged orbital discrepancy 47 00:02:11,343 --> 00:02:15,498 to predict the existence of some new planet in the Solar system. 48 00:02:16,292 --> 00:02:19,006 They have always been wrong. 49 00:02:20,141 --> 00:02:22,307 The most famous of these erroneous predictions 50 00:02:22,331 --> 00:02:23,769 came from Percival Lowell, 51 00:02:23,793 --> 00:02:28,504 who was convinced that there must be a planet just beyond Uranus and Neptune, 52 00:02:28,528 --> 00:02:30,520 messing with those orbits. 53 00:02:30,544 --> 00:02:33,107 And so when Pluto was discovered in 1930, 54 00:02:33,131 --> 00:02:34,774 at the Lowell Observatory, 55 00:02:34,798 --> 00:02:38,780 everybody assumed that it must be the planet that Lowell had predicted. 56 00:02:39,244 --> 00:02:41,180 They were wrong. 57 00:02:41,680 --> 00:02:45,747 It turns out, Uranus and Neptune are exactly where they're supposed to be. 58 00:02:45,771 --> 00:02:47,363 It took 100 years, 59 00:02:47,387 --> 00:02:49,133 but Bouvard was eventually right. 60 00:02:49,157 --> 00:02:52,775 Astronomers needed to do better measurements. 61 00:02:52,799 --> 00:02:54,578 And when they did, 62 00:02:54,602 --> 00:02:57,760 those better measurements had turned out that 63 00:02:57,784 --> 00:03:02,808 there is no planet just beyond the orbit of Uranus and Neptune 64 00:03:02,832 --> 00:03:05,506 and Pluto is thousands of times too small 65 00:03:05,530 --> 00:03:08,180 to have any effect on those orbits at all. 66 00:03:08,204 --> 00:03:11,863 So even though Pluto turned out not to be the planet 67 00:03:11,887 --> 00:03:13,466 it was originally thought to be, 68 00:03:13,490 --> 00:03:16,918 it was the first discovery of what is now known to be 69 00:03:16,942 --> 00:03:21,704 thousands of tiny icy objects in orbit beyond the planets. 70 00:03:21,728 --> 00:03:24,601 Here you can see the orbits of Jupiter, 71 00:03:24,625 --> 00:03:27,163 Saturn, Uranus and Neptune, 72 00:03:27,187 --> 00:03:30,187 and in that little circle in the very center is the Earth 73 00:03:30,211 --> 00:03:33,185 and the Sun and almost everything that you know and love. 74 00:03:33,209 --> 00:03:35,028 And those yellow circles at the edge 75 00:03:35,052 --> 00:03:37,789 are these icy bodies out beyond the planets. 76 00:03:37,813 --> 00:03:40,107 These icy bodies are pushed and pulled 77 00:03:40,131 --> 00:03:42,250 by the gravitational fields of the planets 78 00:03:42,274 --> 00:03:44,805 in entirely predictable ways. 79 00:03:44,829 --> 00:03:49,549 Everything goes around the Sun exactly the way it is supposed to. 80 00:03:50,950 --> 00:03:52,108 Almost. 81 00:03:52,132 --> 00:03:54,307 So in 2003, 82 00:03:54,331 --> 00:03:56,227 I discovered, what was at the time, 83 00:03:56,251 --> 00:03:59,592 the most distant known object in the entire Solar system. 84 00:03:59,978 --> 00:04:02,391 It's hard not to look at that lonely body out there 85 00:04:02,415 --> 00:04:04,436 and say, oh yeah sure, so Lowell was wrong, 86 00:04:04,460 --> 00:04:06,373 there was no planet just beyond Neptune, 87 00:04:06,397 --> 00:04:08,669 but this, this could be a new planet. 88 00:04:09,089 --> 00:04:10,617 The real question we had was, 89 00:04:10,641 --> 00:04:12,879 what kind of orbit does it have around the Sun? 90 00:04:12,903 --> 00:04:14,839 Does it go in a circle around the Sun 91 00:04:14,863 --> 00:04:16,441 like a planet should? 92 00:04:16,465 --> 00:04:20,363 Or is it just a typical member of this icy belt of bodies 93 00:04:20,387 --> 00:04:23,886 that got a little bit tossed outward and it's now on its way back in? 94 00:04:24,442 --> 00:04:26,956 This is precisely the question 95 00:04:26,980 --> 00:04:31,236 the astronomers were trying to answer about Uranus 200 years ago. 96 00:04:31,616 --> 00:04:35,412 They did it by using overlooked observations of Uranus 97 00:04:35,436 --> 00:04:39,506 from 91 years before its discovery to figure out its entire orbit. 98 00:04:39,530 --> 00:04:41,553 We couldn't go quite that far back, 99 00:04:41,577 --> 00:04:46,172 but we did find observations of our object from 13 years earlier, 100 00:04:46,196 --> 00:04:48,879 that allowed us to figure out how it went around the Sun. 101 00:04:48,903 --> 00:04:50,101 So the question is, 102 00:04:50,125 --> 00:04:52,934 is it in a circular orbit around the Sun, like a planet, 103 00:04:52,958 --> 00:04:54,332 or is it on its way back in, 104 00:04:54,356 --> 00:04:56,276 like one of these typical icy bodies? 105 00:04:56,300 --> 00:04:57,964 And the answer is 106 00:04:57,988 --> 00:04:59,146 no. 107 00:04:59,170 --> 00:05:02,057 It has a massively elongated orbit 108 00:05:02,081 --> 00:05:05,634 that takes 10,000 years to go around the Sun. 109 00:05:06,049 --> 00:05:08,041 We named this object Sedna, 110 00:05:08,065 --> 00:05:09,946 after the Inuit goddess of the sea 111 00:05:09,970 --> 00:05:14,009 in honor of the cold, icy places where it spends all of its time. 112 00:05:14,033 --> 00:05:15,636 We now know that Sedna, 113 00:05:15,660 --> 00:05:17,414 it's about a third the size of Pluto 114 00:05:17,438 --> 00:05:19,612 and it's a relatively typical member 115 00:05:19,636 --> 00:05:22,358 of those icy bodies out beyond Neptune. 116 00:05:22,382 --> 00:05:26,229 Relatively typical, except for this bizarre orbit. 117 00:05:26,253 --> 00:05:28,022 You might look at this orbit and say, 118 00:05:28,046 --> 00:05:30,776 "Yeah, that's bizarre, 10,000 years to go around the Sun," 119 00:05:30,800 --> 00:05:32,737 but that's not really the bizarre part. 120 00:05:32,761 --> 00:05:34,927 The bizarre part is that in those 10,000 years 121 00:05:34,951 --> 00:05:38,594 Sedna never comes close to anything else in the Solar system. 122 00:05:38,967 --> 00:05:41,285 Even at its closest approach to the Sun, 123 00:05:41,309 --> 00:05:43,611 Sedna is further from Neptune 124 00:05:43,635 --> 00:05:45,785 than Neptune is from the Earth. 125 00:05:47,053 --> 00:05:49,164 If Sedna had had an orbit like this, 126 00:05:49,188 --> 00:05:51,823 that kisses the orbit of Neptune once around the Sun, 127 00:05:51,847 --> 00:05:54,578 that would have actually been really easy to explain. 128 00:05:54,895 --> 00:05:56,634 That would have just been an object 129 00:05:56,658 --> 00:05:58,952 that had been in a circular orbit around the Sun 130 00:05:58,976 --> 00:06:00,387 in that region of icy bodies, 131 00:06:00,411 --> 00:06:02,944 had gotten a little bit too close to Neptune one time, 132 00:06:02,968 --> 00:06:05,784 and then got slingshot out and is now on its way back in. 133 00:06:07,350 --> 00:06:12,056 But Sedna never comes close to anything known in the Solar system 134 00:06:12,080 --> 00:06:14,477 that could have given it that slingshot. 135 00:06:14,501 --> 00:06:16,514 Neptune can't be responsible, 136 00:06:16,538 --> 00:06:18,938 but something had to be responsible. 137 00:06:19,672 --> 00:06:22,609 This was the first time since 1845 138 00:06:22,633 --> 00:06:27,553 that we saw the gravitational effects of something in the outer Solar system, 139 00:06:27,577 --> 00:06:29,444 and didn't know what it was. 140 00:06:30,196 --> 00:06:32,434 I actually thought I knew what the answer was. 141 00:06:33,141 --> 00:06:37,139 Sure, it could have been some distant, giant planet 142 00:06:37,163 --> 00:06:38,443 in the outer Solar system, 143 00:06:38,467 --> 00:06:40,824 but by this time, that idea was so ridiculous 144 00:06:40,848 --> 00:06:42,689 and had been so thoroughly discredited 145 00:06:42,713 --> 00:06:44,514 that I didn't take it very seriously. 146 00:06:44,538 --> 00:06:45,778 But 4.5 billion years ago, 147 00:06:45,802 --> 00:06:50,696 when the Sun formed on a cocoon of hundreds of other stars, 148 00:06:50,720 --> 00:06:51,942 any one of those stars 149 00:06:51,966 --> 00:06:54,641 could have gotten just a little bit too close to Sedna 150 00:06:54,665 --> 00:06:58,109 and perturbed it onto the orbit that it has today. 151 00:06:58,653 --> 00:07:02,541 When that cluster of stars dissipated into the galaxy, 152 00:07:02,565 --> 00:07:06,343 the orbit of Sedna would have been left as a fossil record 153 00:07:06,367 --> 00:07:08,398 of this earliest history of the Sun. 154 00:07:08,855 --> 00:07:10,664 I was so excited by this idea, 155 00:07:10,688 --> 00:07:12,197 by the idea that we could look 156 00:07:12,221 --> 00:07:14,427 at the fossil history of the birth of the Sun, 157 00:07:14,451 --> 00:07:16,053 that I spent the next decade 158 00:07:16,077 --> 00:07:18,807 looking for more objects with orbits like Sedna. 159 00:07:18,831 --> 00:07:22,276 In that ten-year period, I found zero. 160 00:07:22,300 --> 00:07:23,301 (Laughter) 161 00:07:23,325 --> 00:07:26,845 But my colleagues Chad Trujillo and Scott Sheppard, did a better job, 162 00:07:26,869 --> 00:07:29,886 and they have now found several objects with orbits like Sedna, 163 00:07:29,910 --> 00:07:31,680 which is super exciting. 164 00:07:31,704 --> 00:07:33,243 But what's even more interesting 165 00:07:33,267 --> 00:07:35,999 is that they found that all these objects 166 00:07:36,023 --> 00:07:39,942 are not only on these distant, elongated orbits, 167 00:07:39,966 --> 00:07:45,323 they also share a common value of this obscure orbital parameter 168 00:07:45,347 --> 00:07:49,275 that in celestial mechanics we call argument of perihelion. 169 00:07:50,243 --> 00:07:53,196 When they realized it was clustered in argument of perihelion, 170 00:07:53,220 --> 00:07:54,974 they immediately jumped up and down, 171 00:07:54,998 --> 00:07:57,958 saying it must be caused by a distant, giant planet out there, 172 00:07:57,982 --> 00:08:01,076 which is really exciting, except it makes no sense at all. 173 00:08:01,100 --> 00:08:03,641 Let me try to explain it to you why, with an analogy. 174 00:08:03,665 --> 00:08:06,934 Imagine a person walking down a plaza 175 00:08:06,958 --> 00:08:10,299 and looking 45 degrees to his right side. 176 00:08:11,109 --> 00:08:13,117 There's a lot of reasons that might happen, 177 00:08:13,141 --> 00:08:15,054 it's super easy to explain, no big deal. 178 00:08:15,078 --> 00:08:16,960 Imagine now many different people, 179 00:08:16,984 --> 00:08:20,873 all walking in different directions across the plaza, 180 00:08:20,897 --> 00:08:24,198 but all looking 45 degrees to the direction that they're moving. 181 00:08:24,222 --> 00:08:26,238 Everybody's moving in different directions, 182 00:08:26,262 --> 00:08:28,339 everybody's looking in different directions, 183 00:08:28,363 --> 00:08:31,727 but they're all looking 45 degrees to the direction of motion. 184 00:08:31,751 --> 00:08:33,847 What could cause something like that? 185 00:08:34,926 --> 00:08:36,148 I have no idea. 186 00:08:36,172 --> 00:08:39,942 It's very difficult to think of any reason that that would happen. 187 00:08:39,966 --> 00:08:41,291 (Laughter) 188 00:08:41,315 --> 00:08:44,172 And this is essentially what that clustering 189 00:08:44,196 --> 00:08:47,212 in argument of perihelion was telling us. 190 00:08:47,633 --> 00:08:51,196 Scientists were generally baffled and they assumed it must just be a fluke 191 00:08:51,220 --> 00:08:52,545 and some bad observations. 192 00:08:52,569 --> 00:08:54,347 They told the astronomers, 193 00:08:54,371 --> 00:08:56,038 "Do better measurements." 194 00:08:56,776 --> 00:08:59,894 I actually took a very careful look at those measurements, though, 195 00:08:59,918 --> 00:09:01,125 and they were right. 196 00:09:01,149 --> 00:09:03,117 These objects really did all share 197 00:09:03,141 --> 00:09:05,593 a common value of argument of perihelion, 198 00:09:05,617 --> 00:09:07,006 and they shouldn't. 199 00:09:07,030 --> 00:09:09,230 Something had to be causing that. 200 00:09:11,141 --> 00:09:15,417 The final piece of the puzzle came into place in 2016, 201 00:09:15,441 --> 00:09:17,990 when my colleague, Konstantin Batygin, 202 00:09:18,014 --> 00:09:20,633 who works three doors down from me, and I 203 00:09:20,657 --> 00:09:23,268 realized that the reason that everybody was baffled 204 00:09:23,292 --> 00:09:27,632 was because argument of perihelion was only part of the story. 205 00:09:28,021 --> 00:09:30,037 If you look at these objects the right way, 206 00:09:30,061 --> 00:09:34,172 they are all actually lined up in space in the same direction, 207 00:09:34,196 --> 00:09:37,939 and they're all tilted in space in the same direction. 208 00:09:37,963 --> 00:09:42,320 It's as if all those people on the plaza are all walking in the same direction 209 00:09:42,344 --> 00:09:45,439 and they're all looking 45 degrees to the right side. 210 00:09:45,812 --> 00:09:46,998 That's easy to explain. 211 00:09:47,022 --> 00:09:49,222 They're all looking at something. 212 00:09:49,585 --> 00:09:53,704 These objects in the outer Solar system are all reacting to something. 213 00:09:54,982 --> 00:09:56,132 But what? 214 00:09:56,735 --> 00:09:59,727 Konstantin and I spent a year 215 00:09:59,751 --> 00:10:04,561 trying to come up with any explanation other than a distant, giant planet 216 00:10:04,585 --> 00:10:05,831 in the outer Solar system. 217 00:10:05,855 --> 00:10:11,307 We did not want to be the 33rd and 34th people in history to propose this planet 218 00:10:11,331 --> 00:10:13,665 to yet again be told we were wrong. 219 00:10:14,784 --> 00:10:16,545 But after a year, 220 00:10:16,569 --> 00:10:17,879 there was really no choice. 221 00:10:17,903 --> 00:10:20,044 We could come up with no other explanation 222 00:10:20,068 --> 00:10:22,615 other than that that there is a distant, 223 00:10:22,639 --> 00:10:25,885 massive planet on an elongated orbit, 224 00:10:25,909 --> 00:10:27,988 inclined to the rest of the Solar system, 225 00:10:28,012 --> 00:10:30,728 that is forcing these patterns for these objects 226 00:10:30,752 --> 00:10:32,485 in the outer Solar system. 227 00:10:32,792 --> 00:10:34,918 Guess what else a planet like this does. 228 00:10:34,942 --> 00:10:36,823 Remember that strange orbit of Sedna, 229 00:10:36,847 --> 00:10:39,783 how it was kind of pulled away from the Sun in one direction? 230 00:10:39,807 --> 00:10:42,904 A planet like this would make orbits like that all day long. 231 00:10:43,522 --> 00:10:45,522 We knew we were onto something. 232 00:10:45,871 --> 00:10:48,480 So this brings us to today. 233 00:10:48,863 --> 00:10:53,073 We are basically 1845, Paris. 234 00:10:53,097 --> 00:10:54,248 (Laughter) 235 00:10:54,272 --> 00:10:59,621 We see the gravitational effects of a distant, giant planet, 236 00:10:59,645 --> 00:11:01,871 and we are trying to work the calculations 237 00:11:01,895 --> 00:11:04,879 to tell us where to look, to point our telescopes, 238 00:11:04,903 --> 00:11:06,109 to find this planet. 239 00:11:06,133 --> 00:11:08,425 We've done massive suits of computer simulations, 240 00:11:09,307 --> 00:11:11,227 massive months of analytic calculations, 241 00:11:11,251 --> 00:11:13,823 and here's what I cal tell you so far. 242 00:11:13,847 --> 00:11:17,014 First, this planet, which we call Planet Nine, 243 00:11:17,038 --> 00:11:19,621 because that's what it is, 244 00:11:20,768 --> 00:11:23,998 Planet Nine is six times the mass of the Earth. 245 00:11:24,022 --> 00:11:26,268 This is no slightly-smaller-than-Pluto, 246 00:11:26,292 --> 00:11:29,038 let's-all-argue-about whether-it's-a-planet-or-not thing. 247 00:11:29,062 --> 00:11:32,371 This is the fifth largest planet in our entire Solar system. 248 00:11:32,395 --> 00:11:36,037 For context, let me show you the sizes of the planets. 249 00:11:36,061 --> 00:11:39,633 In the back there, you can the massive Jupiter and Saturn. 250 00:11:40,204 --> 00:11:42,840 Next to them, a little bit smaller, Uranus and Neptune. 251 00:11:42,864 --> 00:11:46,355 Up in the corner, the terrestrial planets, Mercury, Venus, Earth and Mars. 252 00:11:46,379 --> 00:11:47,734 You can even see that belt 253 00:11:47,758 --> 00:11:50,877 of icy bodies beyond Neptune, of which Pluto is a member, 254 00:11:50,901 --> 00:11:52,774 good luck figuring out which one it is. 255 00:11:52,798 --> 00:11:55,212 And here is Planet Nine. 256 00:11:56,585 --> 00:11:58,640 Planet Nine is big. 257 00:11:59,046 --> 00:12:00,219 Planet Nine is so big, 258 00:12:00,243 --> 00:12:02,847 you should probably wonder why haven't we found it yet. 259 00:12:02,871 --> 00:12:04,110 Well, Planet Nine is big, 260 00:12:04,134 --> 00:12:06,347 but it's also really, really far away. 261 00:12:06,371 --> 00:12:11,045 It's something like 15 times further away than Neptune. 262 00:12:11,069 --> 00:12:14,347 And that makes it about 50,000 times fainter than Neptune. 263 00:12:14,371 --> 00:12:17,315 And also, the sky is a really big place. 264 00:12:17,339 --> 00:12:19,475 We've narrowed down where we think it is 265 00:12:19,499 --> 00:12:22,037 to a relatively small area of the sky, 266 00:12:22,061 --> 00:12:23,918 but it would still take us years 267 00:12:23,942 --> 00:12:26,324 to systematically cover the area of the sky 268 00:12:26,348 --> 00:12:28,192 with the large telescopes that we need 269 00:12:28,216 --> 00:12:31,101 to see something that's this far away and this faint. 270 00:12:31,474 --> 00:12:33,990 Luckily, we might not have to. 271 00:12:34,729 --> 00:12:39,618 Just like Bouvard used unrecognized observations of Uranus 272 00:12:39,642 --> 00:12:42,387 from 91 years before its discovery, 273 00:12:42,411 --> 00:12:46,192 I bet that there are unrecognized images 274 00:12:46,216 --> 00:12:49,078 that show the location of Planet Nine. 275 00:12:49,984 --> 00:12:53,061 It's going to be a massive computational undertaking 276 00:12:53,085 --> 00:12:55,389 to go through all of the old data, 277 00:12:55,413 --> 00:12:58,331 and pick out that one faint moving planet. 278 00:12:59,276 --> 00:13:00,641 But we're underway. 279 00:13:00,665 --> 00:13:02,990 And I think we're getting close. 280 00:13:03,014 --> 00:13:05,514 So I would say, get ready. 281 00:13:05,538 --> 00:13:09,513 We are not going to match Le Verrier's 282 00:13:09,537 --> 00:13:10,705 "make a prediction, 283 00:13:10,729 --> 00:13:12,633 have the planet found in a single night 284 00:13:12,657 --> 00:13:14,919 that close to where you predicted it" record. 285 00:13:14,943 --> 00:13:18,882 But I do bet that within the next couple of years 286 00:13:18,906 --> 00:13:21,319 some astronomer somewhere 287 00:13:21,343 --> 00:13:23,573 will find a faint point of light, 288 00:13:23,597 --> 00:13:25,866 slowly moving across the sky 289 00:13:25,890 --> 00:13:29,174 and triumphantly announce the discovery of a new, 290 00:13:29,198 --> 00:13:31,635 and quite possibly not the last, 291 00:13:31,659 --> 00:13:33,792 real planet of our Solar system. 292 00:13:34,183 --> 00:13:35,334 Thank you. 293 00:13:35,358 --> 00:13:38,877 (Applause)