WEBVTT 1 00:00:03.439 --> 00:00:07.719 Welcome to Bedtime Astronomy. Explore the wonders of the cosmos 2 00:00:07.759 --> 00:00:12.279 with our soothing Bedtime Astronomy podcast. Each episode offers a 3 00:00:12.359 --> 00:00:16.320 gentle journey through the stars, planets, and beyond, perfect for 4 00:00:16.399 --> 00:00:20.239 unwinding after a long day. Let's travel through the mysteries 5 00:00:20.239 --> 00:00:22.440 of the universe as you drift off into a peaceful 6 00:00:22.480 --> 00:00:23.800 slumber under the night sky. 7 00:00:26.920 --> 00:00:29.399 Welcome back to the show. We are doing something a 8 00:00:29.399 --> 00:00:32.399 little different today. Usually when we sit down to talk 9 00:00:32.399 --> 00:00:36.200 about the bleeding edge of astrophysics, when we try to 10 00:00:36.280 --> 00:00:39.479 visualize what it looks like to steady worlds that are 11 00:00:39.759 --> 00:00:43.079 hundreds of light years away, we all have a very specific, 12 00:00:43.359 --> 00:00:45.600 almost Hollywood style image in our heads. 13 00:00:46.200 --> 00:00:48.920 Oh absolutely, it's the Cape Canaveral aesthetic, isn't it. 14 00:00:48.960 --> 00:00:49.359 Totally. 15 00:00:49.439 --> 00:00:54.240 We picture these massive vertical integration buildings, clouds of steam, 16 00:00:54.439 --> 00:00:57.359 you know, the whole countdown clock thing, and millions of 17 00:00:57.399 --> 00:00:59.600 pounds of thrust just fighting gravity. 18 00:01:00.320 --> 00:01:04.040 It's loud, it's fast, and it involves billions of dollars 19 00:01:04.040 --> 00:01:07.840 of titanium and composites hurling themselves into the vacuum of space. 20 00:01:07.959 --> 00:01:10.359 It's drama, pure raw power, right, and. 21 00:01:10.359 --> 00:01:13.599 So we have this conditioned bias that space science equals rockets. 22 00:01:13.959 --> 00:01:16.680 We just assume that to get high quality data, well, 23 00:01:16.680 --> 00:01:19.200 you need high velocity and extreme altitude. 24 00:01:18.719 --> 00:01:20.239 You need to escape Earth entirely. 25 00:01:20.319 --> 00:01:22.959 That's the assumption. But the documentation we're looking at today, 26 00:01:23.000 --> 00:01:26.120 specifically a fascinating report from Universe Today and fizz dot 27 00:01:26.239 --> 00:01:31.680 org about a mission called Excite, it completely dismantles that assumption. 28 00:01:32.000 --> 00:01:35.480 It really does. It's a wonderful reminder that sometimes the 29 00:01:35.519 --> 00:01:39.159 most sophisticated solution to a really high tech problem isn't 30 00:01:39.159 --> 00:01:43.040 about going faster or higher, or you know, just using 31 00:01:43.079 --> 00:01:43.840 more brute forests. 32 00:01:43.840 --> 00:01:44.760 Look about being smarter. 33 00:01:45.000 --> 00:01:47.359 It's about being smarter with where you put your instruments. 34 00:01:47.400 --> 00:01:50.200 It's about finding the clever workaround. 35 00:01:49.920 --> 00:01:52.280 Right, Because the vehicle at the center of our conversation 36 00:01:52.359 --> 00:01:56.239 today isn't a rocket, not at all. It doesn't have thrusters, 37 00:01:56.280 --> 00:01:59.239 it doesn't have a heat shield. It's a balloon, a. 38 00:01:59.200 --> 00:02:02.599 Balloon, and it's a balloon that, if everything goes according 39 00:02:02.599 --> 00:02:04.840 to plan, is going to tell us more about the 40 00:02:04.879 --> 00:02:08.759 weather on alien planets than perhaps any rocket based telescope 41 00:02:08.800 --> 00:02:12.520 currently in operation. We are talking about the Excite mission. 42 00:02:12.680 --> 00:02:15.520 Let's break down that acronym before we get into the physics. 43 00:02:15.639 --> 00:02:18.400 Because it sounds intense excite. 44 00:02:18.800 --> 00:02:21.879 It does sound pretty energetic. It stands for the Exoplanet 45 00:02:21.879 --> 00:02:25.639 Climate Infrared Telescope. Okay, And while the name suggests all 46 00:02:25.639 --> 00:02:29.120 this high energy and excitement, the actual method of deployment 47 00:02:29.280 --> 00:02:32.719 is remarkably gentle. It's almost floaty, floaty. 48 00:02:32.800 --> 00:02:34.960 I like that. So the plan is to float a 49 00:02:35.000 --> 00:02:38.520 telescope to the very edge of the Earth's atmosphere. 50 00:02:38.000 --> 00:02:41.479 Exactly and just have it sit there to stare uninterrupted 51 00:02:41.560 --> 00:02:44.360 at a very specific type of alien world. 52 00:02:44.520 --> 00:02:47.120 Okay, let's establish the scale here. When we say float 53 00:02:47.159 --> 00:02:50.039 a telescope, I mean, are we talking about something like 54 00:02:50.400 --> 00:02:53.080 a weather balloon you'd see on the local news or 55 00:02:53.120 --> 00:02:56.039 is this more like the red bull stratos jump? How 56 00:02:56.120 --> 00:02:57.560 high are we actually going? 57 00:02:57.919 --> 00:03:02.240 We are definitely talking stratospheric think, much much bigger than 58 00:03:02.240 --> 00:03:05.439 a standard weather balloon. The mission profile calls for an 59 00:03:05.479 --> 00:03:06.680 altitude of forty. 60 00:03:06.520 --> 00:03:09.400 Kilometers forty kilometers yep, and to put that. 61 00:03:09.319 --> 00:03:11.599 In imperial units for those of us who think that way, 62 00:03:11.639 --> 00:03:14.039 that's roughly twenty five miles straight out. 63 00:03:14.199 --> 00:03:16.800 Twenty five miles Okay. Can you contextualize that for me? 64 00:03:16.879 --> 00:03:18.680 If I'm looking out the window of a seven forty 65 00:03:18.680 --> 00:03:21.759 seven on a transatlantic flight. How far above me is 66 00:03:21.800 --> 00:03:22.319 this balloon? 67 00:03:22.439 --> 00:03:25.520 Right, So a commercial jet cruises at what between thirty thousand, 68 00:03:25.599 --> 00:03:27.879 forty thousand feet some like that. Yeah, so that's roughly 69 00:03:28.000 --> 00:03:30.960 ten to twelve kilometers up. This balloon is going four 70 00:03:31.080 --> 00:03:32.000 times higher than a. 71 00:03:32.000 --> 00:03:33.680 Commercial flight, four times higher. 72 00:03:33.800 --> 00:03:36.280 If you were in that jet looking up, the balloon 73 00:03:36.319 --> 00:03:38.879 would still be just a tiny dot in the black 74 00:03:38.919 --> 00:03:41.000 sky above you. It's not in the blue part of 75 00:03:41.039 --> 00:03:44.120 the sky anymore. It is cruising the upper stratosphere. 76 00:03:44.319 --> 00:03:46.960 But and this is a really important distinction we need 77 00:03:47.000 --> 00:03:51.199 to make. It's not technically space. Is it the Carmen line, 78 00:03:51.240 --> 00:03:53.800 which is sort of the international welcome to space sign, 79 00:03:54.199 --> 00:03:56.280 that's at one hundred kilometers. 80 00:03:55.680 --> 00:04:00.159 Correct, It is not technically outer space. You are still 81 00:04:00.199 --> 00:04:03.120 within the influence of Earth's atmosphere thin as it is 82 00:04:03.199 --> 00:04:06.919 up there. But here's the thing. For the specific scientific 83 00:04:07.000 --> 00:04:10.879 problem they're trying to solve. Forty kilometers is the magic number. 84 00:04:10.680 --> 00:04:11.319 The sweet spot. 85 00:04:11.360 --> 00:04:13.360 It's the absolute sweet spot where you get I mean, 86 00:04:13.400 --> 00:04:15.759 something like ninety nine percent of the benefits of being 87 00:04:15.759 --> 00:04:19.240 in space, but without the billion dollar price tag of 88 00:04:19.240 --> 00:04:20.040 a rocket launch. 89 00:04:20.360 --> 00:04:22.959 I want to really dig into that magic number concept, 90 00:04:23.120 --> 00:04:25.399 because that really seems to be the lynchpin of this 91 00:04:25.480 --> 00:04:29.800 whole project's economic and scientific argument. But first, what exactly 92 00:04:29.920 --> 00:04:32.360 is XITE looking at? You mentioned alien weather. 93 00:04:32.560 --> 00:04:36.199 Yes, the target is a very specific, very dramatic class 94 00:04:36.199 --> 00:04:37.839 of planets known as hot jupiters. 95 00:04:38.199 --> 00:04:40.480 Hot jupiters. It's a vivid name. 96 00:04:40.560 --> 00:04:43.439 It implies a lot, it does, and it's quite literal. Actually, 97 00:04:43.480 --> 00:04:47.399 these are gas giants, so planets with the mass and 98 00:04:47.439 --> 00:04:51.319 composition roughly similar to our own Jupiter. But they are 99 00:04:51.360 --> 00:04:54.000 not sitting out in the cold suburbs of their solar 100 00:04:54.040 --> 00:04:55.639 systems like our Jupiter. 101 00:04:55.319 --> 00:04:56.959 Is right Jupiter's way out there. 102 00:04:57.040 --> 00:05:00.800 These guys orbit incredibly close to their parent stars. 103 00:05:01.120 --> 00:05:02.959 How close are we talking? I mean, Mercury is close 104 00:05:03.000 --> 00:05:04.079 to our Sun is like. 105 00:05:04.000 --> 00:05:06.920 That, oh much much closer, so close that a year 106 00:05:07.319 --> 00:05:10.160 one full orbit around their star might only last two 107 00:05:10.279 --> 00:05:11.279 or three Earth days. 108 00:05:11.399 --> 00:05:14.639 Two or three days. That is incredibly fast. So they 109 00:05:14.639 --> 00:05:16.240 are just speed running their orbit. 110 00:05:16.360 --> 00:05:19.759 They are They're absolutely whipping around their stars. And because 111 00:05:19.759 --> 00:05:22.079 they are that close, they are just roasting. I can 112 00:05:22.120 --> 00:05:25.920 engine temperatures on the starfacing side can reach thousands of degrees. 113 00:05:26.480 --> 00:05:29.000 We are talking about worlds that are essentially glowing with 114 00:05:29.040 --> 00:05:32.279 their own heat, where the atmosphere is being constantly blasted 115 00:05:32.319 --> 00:05:33.560 by stellar radiation. 116 00:05:33.839 --> 00:05:37.240 So we have these massive, scorching, fast moving planets, and 117 00:05:37.319 --> 00:05:41.120 Excite is designed to map the climate of these these. 118 00:05:41.000 --> 00:05:44.360 Hellscapes, that's a good word for them, exactly. But to 119 00:05:44.399 --> 00:05:47.560 do that, you immediately run into a massive obstacle in 120 00:05:47.639 --> 00:05:51.199 observational astronomy. To see the heat signature of a planet, 121 00:05:51.279 --> 00:05:54.839 you need to observe in the infrared part of the spectrum. Infrared, 122 00:05:54.879 --> 00:05:57.839 that's heat radiation right right our eyes see visible light. 123 00:05:58.240 --> 00:06:00.240 But if you want to see temperature, if you want 124 00:06:00.240 --> 00:06:03.000 to see the thermal glow of a hot planet against 125 00:06:03.000 --> 00:06:06.720 the cold darkness of space, you have to look in infrared. 126 00:06:07.000 --> 00:06:08.000 It's the only. 127 00:06:07.800 --> 00:06:09.439 Way, Okay, So what's the problem with that. 128 00:06:09.759 --> 00:06:14.519 The problem is Earth's atmosphere absolutely hates infrared light. 129 00:06:14.519 --> 00:06:16.240 Hates it in what way it absorbs it. 130 00:06:16.360 --> 00:06:19.480 Specifically the water vapor in our atmosphere. You can think 131 00:06:19.480 --> 00:06:24.639 about humidity. Water molecules are incredibly good at absorbing infrared energy. 132 00:06:24.879 --> 00:06:28.079 It's the greenhouse effect basically. So if you put an 133 00:06:28.079 --> 00:06:30.680 infrared telescope on the ground, even on a super high 134 00:06:30.680 --> 00:06:33.720 Mountain in Hawaii or the Atacama Desert in Chile, where 135 00:06:33.720 --> 00:06:37.000 the air is really thin. You are still looking through 136 00:06:37.040 --> 00:06:39.639 this thick, soupy blanket of water vapor. 137 00:06:40.000 --> 00:06:42.560 So the signal from the planet just gets lost in 138 00:06:42.639 --> 00:06:44.360 the noise of our own atmosphere. 139 00:06:44.519 --> 00:06:47.439 It's worse than noise, it's a total block edge at 140 00:06:47.480 --> 00:06:49.600 certain wavelengths. It's like trying to look at the stars 141 00:06:49.639 --> 00:06:54.319 on a foggy night, or trying to see through steamy window. 142 00:06:54.399 --> 00:06:55.879 The signal just doesn't get through. 143 00:06:56.040 --> 00:06:57.279 And this is where the balloon comes in. 144 00:06:57.480 --> 00:06:58.680 This is where the balloon is the hero. 145 00:06:58.959 --> 00:07:00.959 Back to the forty kilometer figure right. 146 00:07:00.839 --> 00:07:03.240 Because if you can get a telescope up to forty kilometers, 147 00:07:03.519 --> 00:07:07.160 you are physically above ninety nine point five percent of 148 00:07:07.160 --> 00:07:10.319 the art's atmosphere. More importantly, you're above almost all of 149 00:07:10.319 --> 00:07:11.120 the water vapor. 150 00:07:11.240 --> 00:07:14.480 So suddenly the fog clears, the steamy window becomes transparent. 151 00:07:14.560 --> 00:07:18.560 Precisely, the sky becomes crystal clear in the infrared frequencies 152 00:07:18.600 --> 00:07:21.399 they need to see for the purpose of this specific 153 00:07:21.399 --> 00:07:25.720 telescope and this specific science. Forty kilometers is space. The 154 00:07:25.759 --> 00:07:28.480 photons from that distant planet can travel all that way 155 00:07:28.560 --> 00:07:31.680 and then hit the detector without bumping into any pesky 156 00:07:31.680 --> 00:07:34.079 water molecules in our atmosphere at the last second. 157 00:07:34.439 --> 00:07:37.480 That is a fascinatingly simple workaround. You don't need to 158 00:07:37.519 --> 00:07:39.800 leave Earth's gravity. You just need to get a blood 159 00:07:39.800 --> 00:07:40.720 the moisture. 160 00:07:40.639 --> 00:07:44.560 And you save a fortune in fuel and hardware doing it. 161 00:07:45.240 --> 00:07:47.519 But there is another layer to this strategy, and it's 162 00:07:47.519 --> 00:07:49.920 a really clever one. It has to do with where 163 00:07:49.959 --> 00:07:51.360 they are planning on launching it. 164 00:07:51.600 --> 00:07:53.240 Oh right, you mentioned this for. 165 00:07:53.279 --> 00:07:56.600 The main long duration mission. They aren't just sending this 166 00:07:56.720 --> 00:08:00.480 up from Florida or New Mexico. The source material highlights 167 00:08:00.519 --> 00:08:02.240 a launch plan for Antarctica. 168 00:08:02.279 --> 00:08:05.759 Antarctica that seems I mean logistically that sounds like a nightmare. 169 00:08:05.959 --> 00:08:07.639 Why go to the bottom of the world to look 170 00:08:07.720 --> 00:08:08.319 up at the sky? 171 00:08:08.680 --> 00:08:12.079 It does seem counterintuitive. There are two main reasons, and 172 00:08:12.079 --> 00:08:16.279 they're both brilliant. First, what are called the seeing conditions. 173 00:08:16.519 --> 00:08:19.639 Seeing conditions it's an astronomy term for how clear and 174 00:08:19.720 --> 00:08:23.680 stable the atmosphere is. The air above Antarctica is very, 175 00:08:23.800 --> 00:08:27.439 very stable. It's incredibly cold, and crucially it's the driest 176 00:08:27.480 --> 00:08:29.959 place on Earth, so you get even less of that 177 00:08:30.079 --> 00:08:31.519 residual water vapor so. 178 00:08:31.480 --> 00:08:33.720 It's the best possible place on Earth to be even 179 00:08:33.720 --> 00:08:35.279 before you go up exactly. 180 00:08:35.679 --> 00:08:38.120 But the second reason, and this is the real game changer, 181 00:08:38.399 --> 00:08:39.159 is about time. 182 00:08:39.480 --> 00:08:39.679 Time. 183 00:08:39.799 --> 00:08:43.600 This brings us to a concept they call loitering. Think 184 00:08:43.639 --> 00:08:47.440 about it. If you launch a satellite into low Earth orbit, 185 00:08:47.679 --> 00:08:50.279 like the Hubble Space Telescope or the International Space Station, 186 00:08:51.000 --> 00:08:55.159 it is moving fast, unbelievably fast. We're taking seventeen thousand 187 00:08:55.159 --> 00:08:58.399 miles per hour something like that. It orbits the entire 188 00:08:58.519 --> 00:09:00.279 Earth every ninety minutes. 189 00:09:00.080 --> 00:09:02.639 So from the satellite's perspective, the sun rises and sets 190 00:09:02.679 --> 00:09:04.120 every hour and a half exactly. 191 00:09:04.200 --> 00:09:07.240 And more importantly, from its perspective, the Earth gets in 192 00:09:07.320 --> 00:09:11.039 the way for roughly half of that orbit, about forty 193 00:09:11.080 --> 00:09:14.519 five minutes. The Earth itself is blocking your view of 194 00:09:14.559 --> 00:09:15.720 the stars you want to see. 195 00:09:15.759 --> 00:09:16.720 You're in Earth's shadow. 196 00:09:16.840 --> 00:09:18.759 You're in the shadow. You can't stare at anything for 197 00:09:18.879 --> 00:09:22.519 very long. It's a constant cycle of observation than blockage. 198 00:09:22.679 --> 00:09:26.399 It's constantly blinking sun shadow, sun shadow. 199 00:09:26.519 --> 00:09:28.159 I can see how that would be a huge problem 200 00:09:28.279 --> 00:09:30.600 if you're trying to, say, film a movie of a 201 00:09:30.639 --> 00:09:33.200 planet's weather system, you'd have these massive gaps in the 202 00:09:33.200 --> 00:09:34.879 footage every forty five minutes. 203 00:09:34.679 --> 00:09:37.200 Precisely, you'd lose all continuity. It would be a mess. 204 00:09:37.320 --> 00:09:40.399 But a balloon over Antarctica during the Antarctic summer. 205 00:09:40.159 --> 00:09:42.440 Ah, the twenty four hour daylight, you got it. 206 00:09:42.679 --> 00:09:45.559 The sun never sets because of the Earth's axial tilt. 207 00:09:45.679 --> 00:09:47.200 It just circles the horizon. 208 00:09:47.320 --> 00:09:49.039 So you never have to worry about the Earth getting 209 00:09:49.039 --> 00:09:49.399 in your. 210 00:09:49.279 --> 00:09:52.200 Way, not if you're looking outwards. If you point your 211 00:09:52.200 --> 00:09:55.120 telescope away from the Sun, the stars are always accessible 212 00:09:55.200 --> 00:09:58.279 twenty four to seven. And because of the polar vortex wines, 213 00:09:58.360 --> 00:10:01.399 these stable circular win that just go around and around 214 00:10:01.399 --> 00:10:05.080 the continent, the balloon just gently circles the pole. 215 00:10:05.279 --> 00:10:07.440 It doesn't fly off towards Australia. 216 00:10:07.080 --> 00:10:09.000 Nope, it just laps the continent. 217 00:10:09.039 --> 00:10:12.679 It loiters, it loiters, and that lets it stare at 218 00:10:12.720 --> 00:10:17.399 a single target, one of these hot jupiters continuously for 219 00:10:17.559 --> 00:10:20.759 days on end, no blinking, no Earth getting in the way, 220 00:10:21.080 --> 00:10:23.639 just a pure, uninterrupted stream of data. 221 00:10:23.720 --> 00:10:25.000 That is the whole ballgame. 222 00:10:25.240 --> 00:10:27.879 And that continuous stream is what allows them to get 223 00:10:27.919 --> 00:10:31.120 the very specific kind of data they are after. The 224 00:10:31.200 --> 00:10:34.559 report mentions something called phase curves, and I really want 225 00:10:34.600 --> 00:10:36.679 to spend some time here because the report makes it 226 00:10:36.720 --> 00:10:38.919 clear this isn't a side project. This is the core 227 00:10:39.000 --> 00:10:39.919 science of the mission. 228 00:10:40.000 --> 00:10:42.759 Yes, this is the holy grail for this kind of science. 229 00:10:42.960 --> 00:10:45.480 It's what you can do with that loitering capability. 230 00:10:45.720 --> 00:10:49.080 Okay, so let's untack this. We usually hear about transits 231 00:10:49.240 --> 00:10:52.519 in exoplanet news. That's how we find most of these planets. Right. 232 00:10:52.720 --> 00:10:54.320 The planet goes in front of the star, the light 233 00:10:54.360 --> 00:10:56.320 from the star dips a tiny bit, and we say, 234 00:10:56.840 --> 00:10:58.039 uh huh, there's a planet there. 235 00:10:58.200 --> 00:11:01.960 Correct. That is the transit method. It's fundamentally looking at 236 00:11:02.000 --> 00:11:06.679 a shadow, a silhouette. It's incredibly powerful. It tells you 237 00:11:06.720 --> 00:11:10.279 the size of the planet, how fast it orbits, and maybe, 238 00:11:10.559 --> 00:11:13.120 if you're lucky and the instrument is good enough, a 239 00:11:13.159 --> 00:11:16.279 little bit about the chemical makeup of the very edges 240 00:11:16.320 --> 00:11:18.639 of its atmosphere as the starlight. 241 00:11:18.200 --> 00:11:21.720 Filters through the edges. That's a keyword, a very keyword. 242 00:11:21.919 --> 00:11:24.240 Then you also have what's called the secondary. 243 00:11:23.759 --> 00:11:26.159 Eclipse, which is the opposite, the opposite. 244 00:11:26.159 --> 00:11:28.879 That's when the planet goes behind the star from our 245 00:11:28.919 --> 00:11:29.440 point of view. 246 00:11:29.519 --> 00:11:30.879 Okay, so it disappears, it. 247 00:11:30.799 --> 00:11:34.120 Disappears completely, and just before it vanishes. We're seeing the 248 00:11:34.240 --> 00:11:37.039 light from the star plus the light reflected and emitted 249 00:11:37.080 --> 00:11:40.080 from the planet's day side. Then it's gone and we 250 00:11:40.399 --> 00:11:41.519 only see the star. 251 00:11:41.720 --> 00:11:44.399 So you subtract the star only light from the star 252 00:11:44.559 --> 00:11:45.679 plus planet light. 253 00:11:45.799 --> 00:11:49.519 And the difference is the light from the planet's day side. 254 00:11:50.039 --> 00:11:52.600 That tells us how bright it is, how hot it 255 00:11:52.679 --> 00:11:56.519 is on that side facing the star. But both of 256 00:11:56.519 --> 00:12:00.679 those methods, transits and secondary eclipses, they're just shots. They 257 00:12:00.679 --> 00:12:01.919 are momentary events. 258 00:12:02.080 --> 00:12:03.759 You see the front when it passes by, or you 259 00:12:03.759 --> 00:12:05.440 see the back before it hides right. 260 00:12:05.879 --> 00:12:08.759 It's like trying to understand a marathon runner. By taking 261 00:12:08.759 --> 00:12:10.840 a single photo of them at the starting line and 262 00:12:10.879 --> 00:12:12.720 a single photo of them at the finish line. 263 00:12:12.759 --> 00:12:13.879 You miss the entire race. 264 00:12:14.240 --> 00:12:16.600 You miss the whole race. You don't know how they 265 00:12:16.600 --> 00:12:19.639 handled the hills. You don't know what their pacing strategy was. 266 00:12:19.720 --> 00:12:22.639 You don't know if they struggled at mile twenty. Phase 267 00:12:22.720 --> 00:12:25.039 curves are the video of the entire race. 268 00:12:25.159 --> 00:12:27.240 So instead of just watching the planet cross the starter 269 00:12:27.399 --> 00:12:30.240 finish line, Excite watches the whole orbit. 270 00:12:30.440 --> 00:12:33.639 It watches the planet go all the way around for days. 271 00:12:33.759 --> 00:12:35.960 And this is where the physics of hot Jupiter's gets 272 00:12:35.960 --> 00:12:38.639 really really cool. Because these planets are so close to 273 00:12:38.679 --> 00:12:42.159 their stars, they are subject to these massive gravitational forces 274 00:12:42.159 --> 00:12:44.440 that lead to a phenomenon called tidal locking. 275 00:12:44.679 --> 00:12:46.759 We see this with our own moon, right, Yeah, we 276 00:12:46.799 --> 00:12:48.559 always see the same face the Moon. 277 00:12:48.799 --> 00:12:52.720 Exactly the same principle. The immense gravity of the star 278 00:12:52.840 --> 00:12:56.120 has grabbed the planet and basically forced it to rotate 279 00:12:56.200 --> 00:12:58.320 at the exact same speed that it orbits. 280 00:12:58.480 --> 00:13:00.799 So one side faces the star. 281 00:13:00.879 --> 00:13:04.919 Forever eternal noon, and the other side faces deep space 282 00:13:05.320 --> 00:13:06.840 forever eternal midnight. 283 00:13:07.039 --> 00:13:10.399 That sounds incredibly extreme. One side must be boiling and 284 00:13:10.440 --> 00:13:13.200 the other must be what near absolute zero. 285 00:13:13.240 --> 00:13:16.320 In theory, yes, if there were no atmosphere, the day 286 00:13:16.360 --> 00:13:18.720 side would be molten rock and metal, and the night 287 00:13:18.799 --> 00:13:22.759 side would be unimaginably cold. But here is the mystery. 288 00:13:23.399 --> 00:13:27.320 These planets do have atmospheres, and atmospheres move heat around 289 00:13:27.960 --> 00:13:32.279 massive supersonic winds. So as we watch this tidally locked 290 00:13:32.279 --> 00:13:35.200 planet orbit its star from our vantage point here on Earth, 291 00:13:35.440 --> 00:13:37.840 we see different amounts of its day and night sides. 292 00:13:37.919 --> 00:13:40.720 We see different phases, just like the phases of our moon. 293 00:13:40.879 --> 00:13:43.200 So we see the full night side, then a crescent 294 00:13:43.240 --> 00:13:44.440 of the day side appears, then. 295 00:13:44.360 --> 00:13:45.879 It gets bigger. We see half in half. That's the 296 00:13:45.919 --> 00:13:48.120 terminator line, the sunrise sunset line. Then we see the 297 00:13:48.120 --> 00:13:49.519 full day side, and then it wins back to a 298 00:13:49.559 --> 00:13:51.360 crescent and finally back to the night side again. 299 00:13:51.679 --> 00:13:55.799 And by measuring the infrared light the heat during all 300 00:13:55.840 --> 00:13:58.360 of those different phases, we can build a map. 301 00:13:58.639 --> 00:14:02.399 We are building a three temperature map of the entire world. 302 00:14:02.679 --> 00:14:04.759 We're not just getting one number for the day side 303 00:14:04.759 --> 00:14:07.519 and one for the night side. We can see the gradient. 304 00:14:07.759 --> 00:14:11.320 We can see how effectively the winds are dragging that 305 00:14:11.399 --> 00:14:14.960 immense heat from the day side around the night side. 306 00:14:15.159 --> 00:14:18.039 So if the night side is surprisingly warm, it means 307 00:14:18.080 --> 00:14:22.320 the winds are really efficient at circulating heat exactly. And 308 00:14:22.360 --> 00:14:24.399 if the night side is freezing cold, it means the 309 00:14:24.440 --> 00:14:27.240 winds aren't doing their job, or the atmosphere is too 310 00:14:27.320 --> 00:14:28.279 thin to hold the heat. 311 00:14:28.360 --> 00:14:31.799 Precisely, we are literally measuring the efficiency of the planetary 312 00:14:31.840 --> 00:14:34.559 heat engine, and we can get even more granular than that. 313 00:14:34.879 --> 00:14:37.519 This is the really wild part. On many of these 314 00:14:37.519 --> 00:14:40.360 hot jupiters we've studied, we find that the hottest point 315 00:14:40.360 --> 00:14:42.559 on the planet isn't where you'd expect it to be. 316 00:14:42.720 --> 00:14:45.679 Wait, how is that possible? If I stand directly under 317 00:14:45.679 --> 00:14:47.639 a heat lamp, the hottest pot is right on top 318 00:14:47.639 --> 00:14:49.639 of my head. That's just basic physics. 319 00:14:49.799 --> 00:14:52.200 It is unless there is a five thousand mile per 320 00:14:52.240 --> 00:14:56.559 hour wind blowing across your head. If the wind is 321 00:14:56.600 --> 00:14:59.879 strong enough, it physically pushes the heated mass of air, 322 00:15:00.399 --> 00:15:03.919 It advects the heat. It shifts the hot spot away 323 00:15:03.919 --> 00:15:06.440 from the point directly under the star, usually to the 324 00:15:06.480 --> 00:15:08.720 ist in the direction of the planet's rotation. 325 00:15:08.960 --> 00:15:11.120 So the hottest part of the day isn't noon, it's 326 00:15:11.120 --> 00:15:12.360 more like three PM. 327 00:15:12.159 --> 00:15:15.440 A very extreme version of that. Yes, And by measuring 328 00:15:15.480 --> 00:15:18.919 exactly where that hot spot is located using the continuous 329 00:15:18.919 --> 00:15:22.960 phase curve, excite can actually calculate the wind speeds and 330 00:15:23.080 --> 00:15:25.840 infer the atmospheric pressure on an alien world. 331 00:15:26.159 --> 00:15:31.240 That is just incredible. We are effectively doing meteorology calculating 332 00:15:31.279 --> 00:15:34.320 wind speeds on a planet that's hundreds of light years 333 00:15:34.360 --> 00:15:38.279 away using a telescope hanging from a balloon floating over Antarctica. 334 00:15:38.360 --> 00:15:40.639 It's a huge leap forward. It moves us from what 335 00:15:40.679 --> 00:15:44.440 some astronomers call stamp collecting, just finding planets and cataloging them, 336 00:15:44.799 --> 00:15:49.360 to characterization, which is actually understanding them as complex, dynamic 337 00:15:49.519 --> 00:15:50.399 physical places. 338 00:15:50.480 --> 00:15:52.480 Now I have to play Devil's advocate here for a minute, 339 00:15:52.519 --> 00:15:55.559 because whenever we talk about space telescopes, there is a giant, 340 00:15:55.639 --> 00:15:58.600 ten billion dollar elephant in the room. We have the 341 00:15:58.679 --> 00:16:03.240 James Webb Space Telescope JWST. It is the most powerful, 342 00:16:03.720 --> 00:16:08.279 most expensive, most advanced observatory humanity has ever built. It's 343 00:16:08.279 --> 00:16:11.960 an infrared telescope. Why on Earth do we need a 344 00:16:11.960 --> 00:16:13.120 balloon if we have WEB. 345 00:16:13.559 --> 00:16:15.600 It's a great question, and it's one that the scientific 346 00:16:15.600 --> 00:16:18.639 community asks itself all the time. You would absolutely think 347 00:16:18.679 --> 00:16:21.720 the ten billion dollar telescope would win every single time, 348 00:16:22.440 --> 00:16:25.960 But ironically WEB actually suffers from being too good for 349 00:16:26.039 --> 00:16:27.279 this specific job. 350 00:16:27.399 --> 00:16:29.360 Too good. How can a telescope be too good? I 351 00:16:29.360 --> 00:16:31.039 don't understand that it's too sensitive. 352 00:16:31.279 --> 00:16:33.320 You have to remember what WEB was originally built for. 353 00:16:33.399 --> 00:16:37.399 Its primary design mission was to see the cosmic dawn. 354 00:16:37.480 --> 00:16:40.399 The very first stars and galaxies. 355 00:16:39.960 --> 00:16:42.519 The first galaxies born after the Big Bang. We're talking 356 00:16:42.559 --> 00:16:46.039 about objects that are incredibly far away, incredibly red shifted, 357 00:16:46.080 --> 00:16:47.720 and unbelievably faint. 358 00:16:47.799 --> 00:16:50.039 So it's designed to see a single candle on the Moon. 359 00:16:50.240 --> 00:16:52.919 It's designed to see something even fainter than that. So 360 00:16:53.000 --> 00:16:55.360 what happens when you take that exquisite instrument and you 361 00:16:55.440 --> 00:16:58.399 point it at a relatively bright star in our local 362 00:16:58.440 --> 00:17:03.279 galactic neighborhood. It's over It's completely overwhelmed. It's like using 363 00:17:03.480 --> 00:17:07.880 military grade night vision goggles to stare directly at a 364 00:17:07.920 --> 00:17:09.480 football stadium's floodlights. 365 00:17:09.519 --> 00:17:12.440 You just see white. You get no information exactly. 366 00:17:12.480 --> 00:17:16.000 The sensors saturate, the pixels on the detector fill up 367 00:17:16.039 --> 00:17:18.759 with electrons faster than the electronics can read them out. 368 00:17:19.160 --> 00:17:22.440 You just lose the data. Astronomers call it blowing out 369 00:17:22.440 --> 00:17:22.960 the image. 370 00:17:22.960 --> 00:17:25.079 So the data is totally useless. 371 00:17:24.759 --> 00:17:27.880 In many cases for the brightest targets. Yes, and this 372 00:17:28.000 --> 00:17:31.440 is especially true for the specific instrument mode on Web 373 00:17:31.720 --> 00:17:35.000 it's called prism that is actually the best tool for 374 00:17:35.039 --> 00:17:39.079 this kind of continuous atmospheric study. Many of the stars 375 00:17:39.079 --> 00:17:42.640 that host these interesting hot jupiters are relatively bright nearby 376 00:17:42.680 --> 00:17:46.559 stars in our galaxy. Web literally cannot look at them 377 00:17:46.559 --> 00:17:47.960 in this mode without getting blinded. 378 00:17:48.039 --> 00:17:51.400 So Excite is filling a really specific niche. It designed 379 00:17:51.400 --> 00:17:54.599 to be less sensitive, which paradoxically allows it to look 380 00:17:54.599 --> 00:17:55.839 at the bright stuff that Web can. 381 00:17:56.039 --> 00:17:58.839 It has a higher dynamic range, that's the technical term. 382 00:17:58.880 --> 00:18:01.000 It can handle the glare. And then, of course there 383 00:18:01.079 --> 00:18:03.519 is the time and cost factor, which we just cannot ignore. 384 00:18:03.759 --> 00:18:08.440 Web's observing time is arguably the most valuable single resource 385 00:18:08.519 --> 00:18:09.559 in all of astronomy. 386 00:18:09.599 --> 00:18:12.039 I can imagine the line to use. It must be 387 00:18:12.160 --> 00:18:12.880 miles long. 388 00:18:13.200 --> 00:18:16.599 The proposal acceptance rate is tiny, something like one in ten, 389 00:18:16.759 --> 00:18:19.720 maybe even less. So to go to the time Allocation 390 00:18:19.759 --> 00:18:24.279 Committee and ask for five continuous days of Web time 391 00:18:24.720 --> 00:18:26.440 to just stare at one. 392 00:18:26.359 --> 00:18:28.519 Planet, that's a very hard cell. 393 00:18:28.640 --> 00:18:32.039 It's an almost impossible cell, because in those five days, 394 00:18:32.160 --> 00:18:35.359 Web could have looked at one hundred distant galaxies, or 395 00:18:35.480 --> 00:18:39.160 analyzed the light from ten different supernovae, or mapped a 396 00:18:39.160 --> 00:18:43.000 star forming region. There's an opportunity cost, a massive opportunity cost. 397 00:18:43.079 --> 00:18:46.279 Excite is a specialist, it's a dedicated mission. It can 398 00:18:46.319 --> 00:18:48.519 afford to just sit there and stare at one target 399 00:18:48.559 --> 00:18:50.759 for a week or more because it isn't competing with 400 00:18:50.839 --> 00:18:52.960 the entire rest of the universe for its attention. 401 00:18:53.160 --> 00:18:55.880