1 00:00:11,724 --> 00:00:14,324 Okay, this is going to be so much fun! 2 00:00:14,359 --> 00:00:15,359 (Laughter) 3 00:00:15,443 --> 00:00:16,864 I'm really glad to be here. 4 00:00:17,515 --> 00:00:19,203 I'm glad you're here, 5 00:00:19,227 --> 00:00:21,060 because that would be a little weird. 6 00:00:21,960 --> 00:00:24,065 I'm glad we're all here. 7 00:00:24,803 --> 00:00:27,656 And by "here," I don't mean here. 8 00:00:29,624 --> 00:00:30,774 Or here. 9 00:00:32,528 --> 00:00:33,680 But here. 10 00:00:33,704 --> 00:00:34,854 I mean Earth. 11 00:00:35,827 --> 00:00:39,770 And by "we," I don't mean those of us in this auditorium, 12 00:00:41,294 --> 00:00:42,764 but life, 13 00:00:42,788 --> 00:00:44,237 all life on Earth -- 14 00:00:44,261 --> 00:00:49,041 (Laughter) 15 00:00:49,080 --> 00:00:51,071 from complex to single-celled, 16 00:00:51,095 --> 00:00:53,419 from mold to mushrooms 17 00:00:53,443 --> 00:00:54,821 to flying bears. 18 00:00:54,845 --> 00:00:56,211 (Laughter) 19 00:00:58,536 --> 00:01:00,045 The interesting thing is, 20 00:01:00,069 --> 00:01:03,100 Earth is the only place we know of that has life -- 21 00:01:03,124 --> 00:01:05,001 8.7 million species. 22 00:01:05,459 --> 00:01:06,714 We've looked other places, 23 00:01:06,738 --> 00:01:08,835 maybe not as hard as we should or we could, 24 00:01:08,859 --> 00:01:10,786 but we've looked and haven't found any; 25 00:01:10,810 --> 00:01:13,086 Earth is the only place we know of with life. 26 00:01:14,118 --> 00:01:15,392 Is Earth special? 27 00:01:16,391 --> 00:01:18,845 This is a question I've wanted to know the answer to 28 00:01:18,869 --> 00:01:20,123 since I was a small child, 29 00:01:20,147 --> 00:01:22,179 and I suspect 80 percent of this auditorium 30 00:01:22,203 --> 00:01:25,211 has thought the same thing and also wanted to know the answer. 31 00:01:25,679 --> 00:01:27,846 To understand whether there are any planets -- 32 00:01:27,870 --> 00:01:30,148 out there in our solar system or beyond -- 33 00:01:30,172 --> 00:01:31,630 that can support life, 34 00:01:31,654 --> 00:01:34,851 the first step is to understand what life here requires. 35 00:01:35,375 --> 00:01:38,938 It turns out, of all of those 8.7 million species, 36 00:01:38,962 --> 00:01:41,160 life only needs three things. 37 00:01:42,532 --> 00:01:45,384 On one side, all life on Earth needs energy. 38 00:01:45,408 --> 00:01:48,893 Complex life like us derives our energy from the sun, 39 00:01:49,817 --> 00:01:51,918 but life deep underground can get its energy 40 00:01:51,942 --> 00:01:53,664 from things like chemical reactions. 41 00:01:53,688 --> 00:01:55,839 There are a number of different energy sources 42 00:01:55,863 --> 00:01:57,106 available on all planets. 43 00:01:57,800 --> 00:01:58,956 On the other side, 44 00:01:58,980 --> 00:02:01,685 all life needs food or nourishment. 45 00:02:02,141 --> 00:02:06,615 And this seems like a tall order, especially if you want a succulent tomato. 46 00:02:06,639 --> 00:02:08,354 (Laughter) 47 00:02:08,378 --> 00:02:11,445 However, all life on Earth derives its nourishment 48 00:02:11,469 --> 00:02:13,499 from only six chemical elements, 49 00:02:13,523 --> 00:02:16,527 and these elements can be found on any planetary body 50 00:02:16,551 --> 00:02:17,887 in our solar system. 51 00:02:18,937 --> 00:02:22,164 So that leaves the thing in the middle as the tall pole, 52 00:02:22,188 --> 00:02:24,142 the thing that's hardest to achieve. 53 00:02:24,166 --> 00:02:26,058 Not moose, but water. 54 00:02:26,082 --> 00:02:28,863 (Laughter) 55 00:02:29,685 --> 00:02:31,479 Although moose would be pretty cool. 56 00:02:31,503 --> 00:02:32,661 (Laughter) 57 00:02:32,685 --> 00:02:38,227 And not frozen water, and not water in a gaseous state, but liquid water. 58 00:02:38,448 --> 00:02:40,901 This is what life needs to survive, all life. 59 00:02:41,380 --> 00:02:44,716 And many solar system bodies don't have liquid water, 60 00:02:44,740 --> 00:02:46,376 and so we don't look there. 61 00:02:46,400 --> 00:02:49,393 Other solar system bodies might have abundant liquid water, 62 00:02:49,417 --> 00:02:50,752 even more than Earth, 63 00:02:50,776 --> 00:02:53,226 but it's trapped beneath an icy shell, 64 00:02:53,250 --> 00:02:55,511 and so it's hard to access, it's hard to get to, 65 00:02:55,535 --> 00:02:58,254 it's hard to even find out if there's any life there. 66 00:03:00,675 --> 00:03:02,720 So that leaves 67 00:03:04,085 --> 00:03:06,029 a few bodies that we should think about. 68 00:03:06,094 --> 00:03:08,523 So let's make the problem simpler for ourselves. 69 00:03:08,547 --> 00:03:11,888 Let's think only about liquid water on the surface of a planet. 70 00:03:11,912 --> 00:03:14,868 There are only three bodies to think about in our solar system, 71 00:03:14,892 --> 00:03:17,474 with regard to liquid water on the surface of a planet, 72 00:03:17,498 --> 00:03:22,324 and in order of distance from the sun, it's: Venus, Earth and Mars. 73 00:03:22,865 --> 00:03:26,237 You want to have an atmosphere for water to be liquid. 74 00:03:26,261 --> 00:03:28,639 You have to be very careful with that atmosphere. 75 00:03:28,663 --> 00:03:32,075 You can't have too much atmosphere, too thick or too warm an atmosphere, 76 00:03:32,099 --> 00:03:35,004 because then you end up too hot like Venus, 77 00:03:35,028 --> 00:03:36,765 and you can't have liquid water. 78 00:03:36,789 --> 00:03:40,742 But if you have too little atmosphere and it's too thin and too cold, 79 00:03:40,766 --> 00:03:42,790 you end up like Mars, too cold. 80 00:03:43,465 --> 00:03:45,940 So Venus is too hot, Mars is too cold, 81 00:03:45,964 --> 00:03:47,128 and Earth is just right. 82 00:03:47,152 --> 00:03:50,627 You can look at these images behind me and you can see automatically 83 00:03:50,651 --> 00:03:53,248 where life can survive in our solar system. 84 00:03:53,896 --> 00:03:55,496 It's a Goldilocks-type problem, 85 00:03:55,520 --> 00:03:58,010 and it's so simple that a child could understand it. 86 00:04:00,052 --> 00:04:01,232 However, 87 00:04:02,050 --> 00:04:04,978 I'd like to remind you of two things 88 00:04:05,002 --> 00:04:07,956 from the Goldilocks story that we may not think about so often 89 00:04:07,980 --> 00:04:10,076 but that I think are really relevant here. 90 00:04:10,656 --> 00:04:11,806 Number one: 91 00:04:12,911 --> 00:04:15,703 if Mama Bear's bowl is too cold 92 00:04:16,433 --> 00:04:18,440 when Goldilocks walks into the room, 93 00:04:19,242 --> 00:04:21,385 does that mean it's always been too cold? 94 00:04:22,425 --> 00:04:25,693 Or could it have been just right at some other time? 95 00:04:26,250 --> 00:04:29,931 When Goldilocks walks into the room determines the answer 96 00:04:29,955 --> 00:04:31,287 that we get in the story. 97 00:04:31,714 --> 00:04:33,444 And the same is true with planets. 98 00:04:33,468 --> 00:04:35,494 They're not static things. They change. 99 00:04:35,518 --> 00:04:37,260 They vary. They evolve. 100 00:04:37,284 --> 00:04:39,326 And atmospheres do the same. 101 00:04:40,550 --> 00:04:42,252 So let me give you an example. 102 00:04:43,176 --> 00:04:45,178 Here's one of my favorite pictures of Mars. 103 00:04:45,203 --> 00:04:48,334 It's not the highest resolution image, it's not the sexiest image, 104 00:04:48,358 --> 00:04:49,861 it's not the most recent image, 105 00:04:49,885 --> 00:04:53,379 but it's an image that shows riverbeds cut into the surface of the planet; 106 00:04:54,520 --> 00:04:57,104 riverbeds carved by flowing, liquid water; 107 00:04:59,115 --> 00:05:04,001 riverbeds that take hundreds or thousands or tens of thousands of years to form. 108 00:05:04,025 --> 00:05:05,643 This can't happen on Mars today. 109 00:05:05,667 --> 00:05:08,148 The atmosphere of Mars today is too thin and too cold 110 00:05:08,172 --> 00:05:10,313 for water to be stable as a liquid. 111 00:05:10,337 --> 00:05:14,685 This one image tells you that the atmosphere of Mars changed, 112 00:05:14,709 --> 00:05:16,741 and it changed in big ways. 113 00:05:17,314 --> 00:05:22,123 And it changed from a state that we would define as habitable, 114 00:05:22,147 --> 00:05:25,737 because the three requirements for life were present long ago. 115 00:05:27,149 --> 00:05:29,217 Where did that atmosphere go 116 00:05:29,241 --> 00:05:32,061 that allowed water to be liquid at the surface? 117 00:05:32,085 --> 00:05:35,432 Well, one idea is it escaped away to space. 118 00:05:35,456 --> 00:05:38,123 Atmospheric particles got enough energy to break free 119 00:05:38,147 --> 00:05:39,800 from the gravity of the planet, 120 00:05:39,824 --> 00:05:42,513 escaping away to space, never to return. 121 00:05:43,037 --> 00:05:45,725 And this happens with all bodies with atmospheres. 122 00:05:45,749 --> 00:05:46,921 Comets have tails 123 00:05:46,945 --> 00:05:50,202 that are incredibly visible reminders of atmospheric escape. 124 00:05:50,226 --> 00:05:53,635 But Venus also has an atmosphere that escapes with time, 125 00:05:53,659 --> 00:05:55,319 and Mars and Earth as well. 126 00:05:55,343 --> 00:05:58,311 It's just a matter of degree and a matter of scale. 127 00:05:58,692 --> 00:06:01,368 So we'd like to figure out how much escaped over time 128 00:06:01,392 --> 00:06:03,508 so we can explain this transition. 129 00:06:05,032 --> 00:06:07,643 How do atmospheres get their energy for escape? 130 00:06:07,667 --> 00:06:09,798 How do particles get enough energy to escape? 131 00:06:09,822 --> 00:06:13,007 There are two ways, if we're going to reduce things a little bit. 132 00:06:13,031 --> 00:06:14,182 Number one, sunlight. 133 00:06:14,206 --> 00:06:17,618 Light emitted from the sun can be absorbed by atmospheric particles 134 00:06:17,642 --> 00:06:19,356 and warm the particles. 135 00:06:19,380 --> 00:06:21,488 Yes, I'm dancing, but they -- 136 00:06:21,512 --> 00:06:22,983 (Laughter) 137 00:06:23,793 --> 00:06:25,705 Oh my God, not even at my wedding. 138 00:06:25,729 --> 00:06:27,221 (Laughter) 139 00:06:27,245 --> 00:06:30,248 They get enough energy to escape and break free 140 00:06:30,272 --> 00:06:32,772 from the gravity of the planet just by warming. 141 00:06:32,796 --> 00:06:35,958 A second way they can get energy is from the solar wind. 142 00:06:36,482 --> 00:06:41,508 These are particles, mass, material, spit out from the surface of the sun, 143 00:06:41,532 --> 00:06:43,936 and they go screaming through the solar system 144 00:06:43,960 --> 00:06:45,745 at 400 kilometers per second, 145 00:06:45,769 --> 00:06:48,363 sometimes faster during solar storms, 146 00:06:48,387 --> 00:06:51,109 and they go hurtling through interplanetary space 147 00:06:51,133 --> 00:06:53,579 towards planets and their atmospheres, 148 00:06:53,603 --> 00:06:55,228 and they may provide energy 149 00:06:55,252 --> 00:06:57,380 for atmospheric particles to escape as well. 150 00:06:57,782 --> 00:06:59,751 This is something that I'm interested in, 151 00:06:59,775 --> 00:07:01,488 because it relates to habitability. 152 00:07:03,278 --> 00:07:06,410 I mentioned that there were two things about the Goldilocks story 153 00:07:06,434 --> 00:07:09,418 that I wanted to bring to your attention and remind you about, 154 00:07:09,442 --> 00:07:11,681 and the second one is a little bit more subtle. 155 00:07:12,405 --> 00:07:15,193 If Papa Bear's bowl is too hot, 156 00:07:16,780 --> 00:07:20,014 and Mama Bear's bowl is too cold, 157 00:07:21,657 --> 00:07:24,768 shouldn't Baby Bear's bowl be even colder 158 00:07:25,681 --> 00:07:27,477 if we're following the trend? 159 00:07:28,795 --> 00:07:31,107 This thing that you've accepted your entire life, 160 00:07:31,131 --> 00:07:34,201 when you think about it a little bit more, may not be so simple. 161 00:07:35,113 --> 00:07:39,141 And of course, distance of a planet from the sun determines its temperature. 162 00:07:39,165 --> 00:07:41,431 This has to play into habitability. 163 00:07:41,455 --> 00:07:44,385 But maybe there are other things we should be thinking about. 164 00:07:44,409 --> 00:07:46,025 Maybe it's the bowls themselves 165 00:07:46,049 --> 00:07:49,105 that are also helping to determine the outcome in the story, 166 00:07:49,129 --> 00:07:50,429 what is just right. 167 00:07:51,365 --> 00:07:54,230 I could talk to you about a lot of different characteristics 168 00:07:54,254 --> 00:07:55,405 of these three planets 169 00:07:55,429 --> 00:07:56,998 that may influence habitability, 170 00:07:57,077 --> 00:07:59,391 but I would like to talk for just a minute or two 171 00:07:59,415 --> 00:08:00,712 about magnetic fields. 172 00:08:01,315 --> 00:08:03,847 Earth has one; Venus and Mars do not. 173 00:08:04,425 --> 00:08:07,548 Magnetic fields are generated in the deep interior of a planet 174 00:08:07,572 --> 00:08:11,289 by electrically conducting churning fluid material 175 00:08:11,313 --> 00:08:14,218 that creates this big old magnetic field that surrounds Earth. 176 00:08:14,242 --> 00:08:16,638 If you have a compass, you know which way north is. 177 00:08:16,662 --> 00:08:18,156 Venus and Mars don't have that. 178 00:08:18,180 --> 00:08:20,094 If you have a compass on Venus and Mars, 179 00:08:20,118 --> 00:08:21,514 congratulations, you're lost. 180 00:08:21,538 --> 00:08:23,441 (Laughter) 181 00:08:23,465 --> 00:08:25,505 Does this influence habitability? 182 00:08:26,775 --> 00:08:28,077 Well, how might it? 183 00:08:29,724 --> 00:08:32,328 Many scientists think that a magnetic field of a planet 184 00:08:32,352 --> 00:08:34,746 serves as a shield for the atmosphere, 185 00:08:34,770 --> 00:08:38,126 deflecting solar wind particles around the planet 186 00:08:38,150 --> 00:08:39,965 in a bit of a force field-type effect 187 00:08:39,989 --> 00:08:42,688 having to do with electric charge of those particles. 188 00:08:43,062 --> 00:08:46,689 I like to think of it instead as a salad bar sneeze guard for planets. 189 00:08:46,713 --> 00:08:48,992 (Laughter) 190 00:08:49,662 --> 00:08:53,043 And yes, my colleagues who watch this later will realize 191 00:08:53,067 --> 00:08:55,611 this is the first time in the history of our community 192 00:08:55,635 --> 00:08:57,914 that the solar wind has been equated with mucus. 193 00:08:57,938 --> 00:08:59,588 (Laughter) 194 00:09:02,377 --> 00:09:05,853 OK, so the effect, then, is that Earth may have been protected 195 00:09:05,877 --> 00:09:07,045 for billions of years, 196 00:09:07,069 --> 00:09:08,920 because we've had a magnetic field. 197 00:09:08,944 --> 00:09:11,123 Atmosphere hasn't been able to escape. 198 00:09:11,147 --> 00:09:13,254 Mars, on the other hand, has been unprotected 199 00:09:13,278 --> 00:09:15,120 because of its lack of magnetic field, 200 00:09:15,144 --> 00:09:17,096 and over billions of years, 201 00:09:17,120 --> 00:09:19,300 maybe enough atmosphere has been stripped away 202 00:09:19,324 --> 00:09:21,917 to account for a transition from a habitable planet 203 00:09:21,941 --> 00:09:23,607 to the planet that we see today. 204 00:09:24,459 --> 00:09:27,448 Other scientists think that magnetic fields 205 00:09:27,472 --> 00:09:29,635 may act more like the sails on a ship, 206 00:09:30,658 --> 00:09:35,695 enabling the planet to interact with more energy from the solar wind 207 00:09:35,719 --> 00:09:38,991 than the planet would have been able to interact with by itself. 208 00:09:39,015 --> 00:09:41,506 The sails may gather energy from the solar wind. 209 00:09:41,530 --> 00:09:44,196 The magnetic field may gather energy from the solar wind 210 00:09:44,220 --> 00:09:47,464 that allows even more atmospheric escape to happen. 211 00:09:47,488 --> 00:09:49,742 It's an idea that has to be tested, 212 00:09:49,766 --> 00:09:51,651 but the effect and how it works 213 00:09:51,675 --> 00:09:52,826 seems apparent. 214 00:09:52,850 --> 00:09:54,001 That's because we know 215 00:09:54,025 --> 00:09:57,100 energy from the solar wind is being deposited into our atmosphere 216 00:09:57,124 --> 00:09:58,275 here on Earth. 217 00:09:58,299 --> 00:10:00,704 That energy is conducted along magnetic field lines 218 00:10:00,728 --> 00:10:02,076 down into the polar regions, 219 00:10:02,100 --> 00:10:04,236 resulting in incredibly beautiful aurora. 220 00:10:04,260 --> 00:10:06,916 If you've ever experienced them, it's magnificent. 221 00:10:06,940 --> 00:10:08,946 We know the energy is getting in. 222 00:10:08,970 --> 00:10:12,003 We're trying to measure how many particles are getting out 223 00:10:12,027 --> 00:10:15,065 and if the magnetic field is influencing this in any way. 224 00:10:16,422 --> 00:10:18,802 So I've posed a problem for you here, 225 00:10:18,826 --> 00:10:20,372 but I don't have a solution yet. 226 00:10:20,396 --> 00:10:21,672 We don't have a solution. 227 00:10:22,402 --> 00:10:24,759 But we're working on it. How are we working on it? 228 00:10:24,783 --> 00:10:27,081 Well, we've sent spacecraft to all three planets. 229 00:10:27,105 --> 00:10:28,581 Some of them are orbiting now, 230 00:10:28,605 --> 00:10:31,677 including the MAVEN spacecraft which is currently orbiting Mars, 231 00:10:31,701 --> 00:10:35,233 which I'm involved with and which is led here, 232 00:10:35,257 --> 00:10:37,066 out of the University of Colorado. 233 00:10:37,090 --> 00:10:39,372 It's designed to measure atmospheric escape. 234 00:10:39,722 --> 00:10:42,196 We have similar measurements from Venus and Earth. 235 00:10:42,653 --> 00:10:44,318 Once we have all our measurements, 236 00:10:44,342 --> 00:10:47,217 we can combine all these together, and we can understand 237 00:10:47,241 --> 00:10:50,658 how all three planets interact with their space environment, 238 00:10:50,682 --> 00:10:51,844 with the surroundings. 239 00:10:51,868 --> 00:10:55,390 And we can decide whether magnetic fields are important for habitability 240 00:10:55,414 --> 00:10:56,572 or not. 241 00:10:57,596 --> 00:10:59,861 Once we have that answer, why should you care? 242 00:10:59,885 --> 00:11:01,185 I mean, I care deeply ... 243 00:11:02,828 --> 00:11:04,834 And financially as well, but deeply. 244 00:11:04,858 --> 00:11:06,700 (Laughter) 245 00:11:07,463 --> 00:11:09,381 First of all, an answer to this question 246 00:11:09,405 --> 00:11:11,508 will teach us more about these three planets, 247 00:11:11,532 --> 00:11:12,692 Venus, Earth and Mars, 248 00:11:12,716 --> 00:11:15,627 not only about how they interact with their environment today, 249 00:11:15,651 --> 00:11:17,578 but how they were billions of years ago, 250 00:11:17,602 --> 00:11:19,664 whether they were habitable long ago or not. 251 00:11:19,688 --> 00:11:21,332 It will teach us about atmospheres 252 00:11:21,356 --> 00:11:23,351 that surround us and that are close. 253 00:11:23,827 --> 00:11:26,011 But moreover, what we learn from these planets 254 00:11:26,035 --> 00:11:28,056 can be applied to atmospheres everywhere, 255 00:11:29,185 --> 00:11:32,098 including planets that we're now observing around other stars. 256 00:11:32,122 --> 00:11:33,877 For example, the Kepler spacecraft, 257 00:11:33,901 --> 00:11:37,109 which is built and controlled here in Boulder, 258 00:11:37,133 --> 00:11:40,418 has been observing a postage stamp-sized region of the sky 259 00:11:40,442 --> 00:11:41,689 for a couple years now, 260 00:11:41,713 --> 00:11:43,941 and it's found thousands of planets -- 261 00:11:43,965 --> 00:11:46,878 in one postage stamp-sized region of the sky 262 00:11:46,902 --> 00:11:50,991 that we don't think is any different from any other part of the sky. 263 00:11:51,515 --> 00:11:53,325 We've gone, in 20 years, 264 00:11:53,349 --> 00:11:57,386 from knowing of zero planets outside of our solar system, 265 00:11:57,410 --> 00:11:59,163 to now having so many, 266 00:11:59,187 --> 00:12:02,326 that we don't know which ones to investigate first. 267 00:12:03,969 --> 00:12:05,429 Any lever will help. 268 00:12:07,239 --> 00:12:10,823 In fact, based on observations that Kepler's taken 269 00:12:10,847 --> 00:12:12,976 and other similar observations, 270 00:12:13,000 --> 00:12:14,169 we now believe that, 271 00:12:14,193 --> 00:12:18,892 of the 200 billion stars in the Milky Way galaxy alone, 272 00:12:19,486 --> 00:12:24,090 on average, every star has at least one planet. 273 00:12:25,519 --> 00:12:27,022 In addition to that, 274 00:12:27,046 --> 00:12:32,747 estimates suggest there are somewhere between 40 billion and 100 billion 275 00:12:32,771 --> 00:12:36,103 of those planets that we would define as habitable 276 00:12:37,039 --> 00:12:38,451 in just our galaxy. 277 00:12:40,490 --> 00:12:42,527 We have the observations of those planets, 278 00:12:42,551 --> 00:12:45,035 but we just don't know which ones are habitable yet. 279 00:12:45,059 --> 00:12:48,665 It's a little bit like being trapped on a red spot -- 280 00:12:48,689 --> 00:12:49,860 (Laughter) 281 00:12:49,884 --> 00:12:51,116 on a stage 282 00:12:52,078 --> 00:12:55,640 and knowing that there are other worlds out there 283 00:12:56,942 --> 00:12:59,718 and desperately wanting to know more about them, 284 00:13:01,074 --> 00:13:05,008 wanting to interrogate them and find out if maybe just one or two of them 285 00:13:05,032 --> 00:13:06,642 are a little bit like you. 286 00:13:08,144 --> 00:13:10,703 You can't do that. You can't go there, not yet. 287 00:13:10,727 --> 00:13:14,720 And so you have to use the tools that you've developed around you 288 00:13:14,744 --> 00:13:16,039 for Venus, Earth and Mars, 289 00:13:16,063 --> 00:13:18,876 and you have to apply them to these other situations, 290 00:13:18,900 --> 00:13:23,596 and hope that you're making reasonable inferences from the data, 291 00:13:23,620 --> 00:13:26,738 and that you're going to be able to determine the best candidates 292 00:13:26,762 --> 00:13:29,161 for habitable planets, and those that are not. 293 00:13:30,639 --> 00:13:33,354 In the end, and for now, at least, 294 00:13:33,378 --> 00:13:36,165 this is our red spot, right here. 295 00:13:36,876 --> 00:13:40,212 This is the only planet that we know of that's habitable, 296 00:13:40,236 --> 00:13:43,427 although very soon we may come to know of more. 297 00:13:43,451 --> 00:13:46,187 But for now, this is the only habitable planet, 298 00:13:46,211 --> 00:13:47,513 and this is our red spot. 299 00:13:48,476 --> 00:13:49,896 I'm really glad we're here. 300 00:13:51,007 --> 00:13:52,182 Thanks. 301 00:13:52,206 --> 00:13:55,437 (Applause)