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 Astronomie 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 --> 00:00:23.839 slumber under the night sky. 7 00:00:26.960 --> 00:00:29.519 Imagine for a moment that the universe is this massive, 8 00:00:30.120 --> 00:00:33.600 complex symphony, but we've only ever listened to it through 9 00:00:33.679 --> 00:00:38.039 a tiny, cheap am radio speaker. You get the melody maybe, 10 00:00:38.159 --> 00:00:40.640 but you're missing ninety nine percent of the instruments, the texture, 11 00:00:40.640 --> 00:00:44.079 the death. Now, imagine someone hands you this full high 12 00:00:44.119 --> 00:00:49.119 definition digital receiver and it's capable of isolating one hundred 13 00:00:49.119 --> 00:00:52.840 and two distinct frequency channels, most of which we've never 14 00:00:52.880 --> 00:00:53.719 even heard before. 15 00:00:53.840 --> 00:00:56.039 That is absolutely the right analogy. 16 00:00:56.200 --> 00:00:59.799 That's sudden explosion of information. That's the perspective shift we're 17 00:01:00.159 --> 00:01:04.040 diving into today. We are talking about NASA's monumental achievement 18 00:01:04.280 --> 00:01:07.359 with the SPHEREx telescope, which has just given us a 19 00:01:07.359 --> 00:01:09.359 completely new way of seeing the cosmos. 20 00:01:09.640 --> 00:01:12.359 It really is the sources we've pulled together all center 21 00:01:12.439 --> 00:01:16.319 on this massive milestone announced by NASA. And this isn't 22 00:01:16.400 --> 00:01:19.959 just some incremental improvement on existing views of the universe. 23 00:01:20.359 --> 00:01:23.680 This is a wholesale, systemic revolution in how we capture 24 00:01:23.680 --> 00:01:26.840 the entire sky. It forces us to redefine what an 25 00:01:26.840 --> 00:01:28.159 all sky map even means. 26 00:01:28.519 --> 00:01:32.439 Okay, let's unpack this. The big news is that SPHEREx 27 00:01:32.879 --> 00:01:35.000 and that stands for a spectro photometer for the history 28 00:01:35.040 --> 00:01:38.879 of the universe, epoch of realization and ICE's. 29 00:01:38.560 --> 00:01:40.640 Explorer, which is a mouthful. 30 00:01:40.359 --> 00:01:43.000 It is, but we absolutely have to explain why every 31 00:01:43.040 --> 00:01:45.760 part of that name is so critical. The news is 32 00:01:45.799 --> 00:01:50.239 that it has successfully completed its first full sky infrared map, 33 00:01:50.840 --> 00:01:53.599 and it did this by capturing the entire cosmos in 34 00:01:53.599 --> 00:01:56.879 an unprecedented one hundred and two distinct bands of infrared 35 00:01:56.959 --> 00:01:57.879 light exactly. 36 00:01:57.959 --> 00:02:02.280 So our mission today is to extract the most critical 37 00:02:02.319 --> 00:02:04.640 insights from this. I mean, it's an astronomical achievement in 38 00:02:04.680 --> 00:02:06.719 every sense of the word. We need to look at 39 00:02:06.799 --> 00:02:09.599 the tech, how they actually built a system capable of this, 40 00:02:09.719 --> 00:02:12.599 the mechanics of it, and then crucially, how this multi 41 00:02:12.639 --> 00:02:16.400 channel high resolution spectral atlas is specifically designed to answer 42 00:02:16.479 --> 00:02:19.599 some of the most fundamental lingering questions we have about 43 00:02:19.599 --> 00:02:23.199 the Universe's origin, its rapid early expansion, and well it's 44 00:02:23.240 --> 00:02:25.439 evolution over fourteen billion years. 45 00:02:25.680 --> 00:02:28.800 And I want to emphasize the value for you, the learner. 46 00:02:29.159 --> 00:02:31.360 This is not just an announcement of a pretty picture. 47 00:02:31.439 --> 00:02:34.120 This is NASA saying we have created one hundred and 48 00:02:34.199 --> 00:02:38.080 two completely unique data fields, one hundred and two separate 49 00:02:38.120 --> 00:02:41.599 maps of the entire cosmos, all at the same time. 50 00:02:41.719 --> 00:02:45.199 It's staggering, and each map is packed with information that 51 00:02:45.319 --> 00:02:48.479 was previously either too faint, too obscured, or was just 52 00:02:48.560 --> 00:02:51.560 hidden in a wavelength we weren't even monitoring. So this 53 00:02:51.639 --> 00:02:54.199 deep dive will reveal what those data streams are designed 54 00:02:54.199 --> 00:02:57.800 to tell us from the universe's absolute infancy, tracing those 55 00:02:57.840 --> 00:03:01.360 fundamental ripples from the moment of inflation, all the way 56 00:03:01.400 --> 00:03:04.919 to locating the molecular ingredients for life in our own 57 00:03:04.960 --> 00:03:09.759 Milky Way galaxy. It's a fantastic in depth shortcut to 58 00:03:09.879 --> 00:03:12.599 understanding one of the most powerful tools in modern astrophysics. 59 00:03:12.680 --> 00:03:15.000 Let's start with the core accomplishment, then the mapping of 60 00:03:15.039 --> 00:03:18.039 the entire sky in infrared light. It sounds simple when 61 00:03:18.080 --> 00:03:19.639 you say it like that, but the scope is just 62 00:03:19.840 --> 00:03:22.159 enormous and the choice of infrared is really the wnchpin 63 00:03:22.199 --> 00:03:22.919 of the whole mission. 64 00:03:23.240 --> 00:03:26.280 And crucially, this is energy the human eye can't detect. 65 00:03:27.360 --> 00:03:29.800 Infrared light. We often think of it as heat radiation, 66 00:03:30.319 --> 00:03:33.719 and it's absolutely everywhere in the cosmos revelent. Yeah, it's 67 00:03:33.759 --> 00:03:36.919 the light from cooler objects like dust and certain molecules, 68 00:03:37.360 --> 00:03:39.759 and it's also the light from the most distant objects 69 00:03:40.240 --> 00:03:44.319 stretched by the universe's expansion. If you're only looking invisible light, 70 00:03:44.680 --> 00:03:47.319 you're missing most of the action and you're often blocked 71 00:03:47.319 --> 00:03:48.719 completely by cosmic dust. 72 00:03:49.319 --> 00:03:52.240 The ability of infrared light to pierce through those dense, 73 00:03:52.439 --> 00:03:56.639 dusty nebulae is it's paramount here. Stars and planets are 74 00:03:56.639 --> 00:03:59.599 born in these huge clouds of gas and dust. They're 75 00:03:59.639 --> 00:04:02.360 like oh paque curtains. In the visible spectrum, you can't 76 00:04:02.360 --> 00:04:04.840 see a thing, not a thing. But in for red light, 77 00:04:04.960 --> 00:04:08.159 with its longer wavelengths, it just slips right through that curtain. 78 00:04:08.560 --> 00:04:11.199 It allows us to see the actual heat the molecular 79 00:04:11.280 --> 00:04:15.000 signatures of the stellar nurseries. Within SPHEERX isn't trying to 80 00:04:15.039 --> 00:04:18.680 find new visible light objects. It's trying to see the 81 00:04:18.720 --> 00:04:21.519 objects that are defined by their invisibility, and. 82 00:04:21.480 --> 00:04:25.040 The timeline for this mission's initial phase is just incredibly tight. 83 00:04:25.279 --> 00:04:27.879 It is so the sphex mission launched in March twenty 84 00:04:27.920 --> 00:04:30.959 twenty five and began systematic sky mapping by May, just 85 00:04:31.000 --> 00:04:35.040 a couple months barely, and by December eighteenth, twenty twenty five, 86 00:04:35.160 --> 00:04:37.120 so just about six months after the censors turned on, 87 00:04:37.199 --> 00:04:40.319 it completed its first all sky mosaic six months. In 88 00:04:40.439 --> 00:04:43.800 just half a year, it viewed space in every single direction, 89 00:04:44.120 --> 00:04:47.319 capturing three hundred and sixty degrees of the celestial sphere. 90 00:04:47.480 --> 00:04:50.360 A six month turnaround for a map of the entire universe, 91 00:04:51.319 --> 00:04:54.519 especially one with that much complex spectral data, that sounds 92 00:04:54.600 --> 00:04:58.240 almost impossibly fast. It makes me wonder how robust can 93 00:04:58.279 --> 00:05:01.720 a single six month scan really? Are we talking about 94 00:05:01.800 --> 00:05:04.160 high quality final data right out of the gate. 95 00:05:04.319 --> 00:05:06.839 That's a critical question, and the answer is that this 96 00:05:07.000 --> 00:05:10.040 first mosaic is really just the foundation. The sources confirm 97 00:05:10.120 --> 00:05:12.879 that Spherrex is designed as a marathon, a systematic survey 98 00:05:12.879 --> 00:05:16.079 that requires repetition. Its primary mission is set for two 99 00:05:16.199 --> 00:05:18.920 years two years, and during that time it will complete 100 00:05:18.959 --> 00:05:21.800 three additional all sky scans, so it's going to view 101 00:05:21.839 --> 00:05:24.000 the entire sky four times. Over two years. 102 00:05:24.160 --> 00:05:26.399 So it's not just one one oh two channel map, 103 00:05:26.800 --> 00:05:30.639 but four overlapping maps of the entire sky, all layered 104 00:05:30.680 --> 00:05:34.240 on top of each other. Why why is that layering necessary? 105 00:05:34.240 --> 00:05:35.639 What does that biome? Scientifically? 106 00:05:35.720 --> 00:05:39.480 Precisely merging those formaps together is fundamentally about increasing the 107 00:05:39.519 --> 00:05:42.120 signal to noise ratio. Okay, think of it like taking 108 00:05:42.240 --> 00:05:45.720 four long exposures with a camera instead of one short one. 109 00:05:45.800 --> 00:05:49.959 Each time SPHEREx scans a region, it collects more photons, 110 00:05:50.199 --> 00:05:54.120 more information. By co adding the data from all four passes, 111 00:05:54.240 --> 00:05:58.120 they can significantly increase the sensitivity of the measurements. It 112 00:05:58.199 --> 00:06:01.399 lets them detect fainter, more distant objects with much greater 113 00:06:01.480 --> 00:06:05.000 confidence and filter out you know, transient noise like cosmic 114 00:06:05.079 --> 00:06:06.199 rays hitting the detector. 115 00:06:06.560 --> 00:06:10.360 That systematic repetition for complete scans. Yeah, that must be 116 00:06:10.439 --> 00:06:13.959 absolutely essential for the mission's cosmological golds, especially when you're 117 00:06:13.959 --> 00:06:17.279 trying to marror these tiny, subtle differences in how galaxies 118 00:06:17.319 --> 00:06:19.199 are clustered billions of light years away. 119 00:06:19.360 --> 00:06:22.360 Absolutely, And here's a crucial detail that really aligns with 120 00:06:22.519 --> 00:06:26.959 the collaborative ethos of modern space science. What's that the 121 00:06:27.120 --> 00:06:30.120 entire data set, all four scans all the co added 122 00:06:30.199 --> 00:06:33.720 final maps, all the raw spectral information is being made 123 00:06:33.759 --> 00:06:37.279 freely available to scientists and to the public. 124 00:06:37.439 --> 00:06:37.759 Wow. 125 00:06:38.040 --> 00:06:42.399 This completely democratizes the discovery process globally. It ensures that 126 00:06:42.720 --> 00:06:46.600 every research institution, regardless of its size, can dig into 127 00:06:46.639 --> 00:06:48.399 the deepest mysteries of the universe. 128 00:06:48.720 --> 00:06:52.120 That public access feature seems critical. What's the precedent for 129 00:06:52.199 --> 00:06:55.600 releasing such a massive spectral data set so quickly? Is 130 00:06:55.639 --> 00:06:57.800 that typical for emission of this scale. 131 00:06:57.920 --> 00:07:01.240 It's becoming the gold standard, particularly for survey emissions like this. 132 00:07:01.920 --> 00:07:04.560 The sheer vastness of the data I mean, spanning one 133 00:07:04.639 --> 00:07:08.040 hundred and two unique channels across the entire sky, no 134 00:07:08.199 --> 00:07:11.279 single team could ever exploit its full scientific potential on 135 00:07:11.319 --> 00:07:11.600 their own. 136 00:07:11.800 --> 00:07:12.399 Just just too much. 137 00:07:12.680 --> 00:07:16.279 Exactly. By making it immediately public, NASA ensures that thousands 138 00:07:16.279 --> 00:07:20.079 of independent researchers, from planetary scientists to cosmologists, can apply 139 00:07:20.120 --> 00:07:22.920 their specific expertise to different subsets of the data, all 140 00:07:22.920 --> 00:07:25.839 at the same time. It just accelerates discovery exponentially. 141 00:07:26.079 --> 00:07:27.800 But let's go back to those one hundred and two 142 00:07:27.839 --> 00:07:32.040 spectral channels. For a non astrophysicist, it's still a bit abstract. 143 00:07:32.800 --> 00:07:35.319 I find it hard to picture what having one hundred 144 00:07:35.319 --> 00:07:39.480 and two specific measurements of invisible light actually means in practice. 145 00:07:39.560 --> 00:07:42.920 What information is being separated by these distinct wavelengths. Well, 146 00:07:42.959 --> 00:07:45.319 the number one of two is a technological and scientific 147 00:07:45.360 --> 00:07:50.240 sweet spot. It's a compromise between survey speed scanning the 148 00:07:50.279 --> 00:07:54.120 whole sky quickly, and spectral resolution getting enough detail to 149 00:07:54.199 --> 00:07:57.600 identify materials and measure distances. The source Maduig exists some 150 00:07:57.600 --> 00:08:00.199 really concrete examples. Okay, give us an example of this 151 00:08:00.279 --> 00:08:01.240 separation in action. 152 00:08:01.399 --> 00:08:04.319 All right, Consider a star forming region. In one set 153 00:08:04.319 --> 00:08:08.120 of say ten spectral channels. The emissions might be completely 154 00:08:08.160 --> 00:08:11.720 dominated by the light from hot, massive young stars. Okay, 155 00:08:12.079 --> 00:08:14.800 that data would show up as these bright energetic points, 156 00:08:14.839 --> 00:08:17.639 maybe looking blue or white if we assign them visible colors. 157 00:08:18.079 --> 00:08:21.120 But shift your focus just slightly to a different set 158 00:08:21.120 --> 00:08:24.079 of channels centered around say four to eight microns and 159 00:08:24.120 --> 00:08:27.439 the other red, and suddenly you see something completely different. 160 00:08:27.480 --> 00:08:29.079 You lose the stars and you gain the dust. 161 00:08:29.399 --> 00:08:33.639 Right precisely, you gain the thermal radiation that's emitted by 162 00:08:33.679 --> 00:08:36.159 the cosmic dust grains that have been heated up by 163 00:08:36.159 --> 00:08:39.440 those very stars. Cosmic dust, like you said, is critical 164 00:08:39.480 --> 00:08:42.279 for forming new stars and planets, but it's the ultimate 165 00:08:42.360 --> 00:08:47.279 obscure invisible light right. SPHERX captures this dust brilliantly because 166 00:08:47.279 --> 00:08:51.600 it radiates so strongly in specific infrared bands, and conversely, 167 00:08:51.679 --> 00:08:55.080 the source mentions that the same dust is totally invisible 168 00:08:55.080 --> 00:08:55.559 in others. 169 00:08:55.840 --> 00:08:59.200 So you have one map where a massive star forming 170 00:08:59.240 --> 00:09:01.840 nebula is a glowing beacon of heat, and then you 171 00:09:01.919 --> 00:09:05.480 have a complimentary map where that same nebula just disappears entirely, 172 00:09:05.759 --> 00:09:09.360 leaving only the background stars exactly. The scientific breakthrough isn't 173 00:09:09.399 --> 00:09:12.519 just the map itself, it's the comparison and synthesis of 174 00:09:12.679 --> 00:09:14.039 all one hundred and two of those maps. 175 00:09:14.159 --> 00:09:17.720 That's it. Each channel acts as a targeted filter. It's 176 00:09:17.720 --> 00:09:21.559 picking up the unique emission signatures, the fingerprints of specific atoms, 177 00:09:21.639 --> 00:09:25.240 or ions or cold molecules. Comparing the intensity across those 178 00:09:25.240 --> 00:09:27.919 one hundred and two channels, less astronomers figure out not 179 00:09:27.960 --> 00:09:29.440 only what is present like. 180 00:09:29.399 --> 00:09:31.159 Carbon monoxide, water, ice, hot. 181 00:09:31.080 --> 00:09:34.720 Hydrogen exactly, but also how distant it is and how 182 00:09:34.840 --> 00:09:35.679 much of it there is. 183 00:09:36.000 --> 00:09:38.360 This is where it gets really interesting, because this mission's 184 00:09:38.519 --> 00:09:42.919 unique ability to combine this massive scale with such a wide, 185 00:09:43.039 --> 00:09:47.799 rich spectrum earned it this fantastic memorable nickname. 186 00:09:47.600 --> 00:09:50.679 Ah yes, the comparison to the Ultimate Eye and the 187 00:09:50.679 --> 00:09:51.440 Animal Kingdom. 188 00:09:51.679 --> 00:09:51.960 Yes. 189 00:09:52.279 --> 00:09:55.480 Beth Favinsky, the sphere X project manager at JPL, she 190 00:09:55.559 --> 00:09:58.000 called it the Mantis Shrimp of telescopes. 191 00:09:58.519 --> 00:10:01.120 That is instantly memorable and it's such a high bar 192 00:10:01.679 --> 00:10:03.879 for those who don't know. The manta shrimp is famous 193 00:10:03.879 --> 00:10:06.799 for having one of the most complex visual systems in nature. 194 00:10:07.360 --> 00:10:10.960 It can see up to sixteen different types of photoreceptors. 195 00:10:10.320 --> 00:10:11.240 Compared to R three. 196 00:10:11.399 --> 00:10:15.559 Exactly. It sees channels for ultraviolet light, polarized light. Stuff 197 00:10:15.600 --> 00:10:17.320 that's way beyond what we can. 198 00:10:17.200 --> 00:10:20.559 Perceive, and the analogy holds up perfectly for spherx's function. 199 00:10:20.960 --> 00:10:23.879 The telescope's real power is that it combines this amazing 200 00:10:24.000 --> 00:10:27.879 multicolored detection system one hundred and two spectral channels with 201 00:10:28.039 --> 00:10:31.159 the ability to survey a massive, wide swath of its 202 00:10:31.159 --> 00:10:33.000 surroundings the entire sky, and. 203 00:10:32.960 --> 00:10:34.360 To do it over and over again quickly. 204 00:10:34.600 --> 00:10:37.039 That's the key. It's not just seeing many colors in 205 00:10:37.080 --> 00:10:40.799 one tiny spot like GWST does. It's seeing everything in 206 00:10:40.840 --> 00:10:43.799 one hundred and two colors every six months. It's the 207 00:10:44.039 --> 00:10:46.519 ultimate cosmic spectral survey machine. 208 00:10:46.559 --> 00:10:49.759 The mantis shrimp is a brilliant analogy for the result 209 00:10:50.000 --> 00:10:52.480 the richness of the data. But let's shift our deep 210 00:10:52.519 --> 00:10:55.360 dive into the engineering behind the How How does a 211 00:10:55.399 --> 00:10:58.600 telescope manage to generate one hundred and two separate spectral 212 00:10:58.639 --> 00:11:01.159 maps at the same time with this kind of speed 213 00:11:01.240 --> 00:11:01.960 in coverage? 214 00:11:02.080 --> 00:11:06.320 This brings us to the core scientific technique driving the mission. Spectroscopy. 215 00:11:07.039 --> 00:11:10.399 At its heart, spectroscopy is just the process of separating 216 00:11:10.440 --> 00:11:12.240 the light from a source into its. 217 00:11:12.120 --> 00:11:14.200 Component wavelengths, into its colors. 218 00:11:13.879 --> 00:11:17.279 Into its colors exactly. So when SPHEREx says it detects 219 00:11:17.320 --> 00:11:19.960 one hundred and two spectral bands, it means it is 220 00:11:20.039 --> 00:11:22.679 precisely measuring the intensity of light at one hundred and 221 00:11:22.679 --> 00:11:26.840 two specific, narrowly defined points all across the infrared spectrum. 222 00:11:26.919 --> 00:11:29.399 So it's not just painting a general infrared picture. It's 223 00:11:29.679 --> 00:11:33.559 quantitatively measuring the specific fingerprints of light emitted by different 224 00:11:33.600 --> 00:11:36.279 atoms and molecules out there. It's doing chemistry on a 225 00:11:36.320 --> 00:11:37.159 cosmic scale. 226 00:11:37.240 --> 00:11:42.279 That's precisely right. Every element, every common molecule, hydrogen, oxygen, 227 00:11:42.360 --> 00:11:45.840 carbon dioxide, and every physical process in the universe from 228 00:11:45.879 --> 00:11:50.080 the extremely hot glow of Equasar to the cold complex 229 00:11:50.200 --> 00:11:54.519 organic molecules hidden in dust clouds has a unique spectral signature. 230 00:11:55.200 --> 00:11:58.200 By sampling one hundred and two points across that spectrum, 231 00:11:58.360 --> 00:12:02.399 SPHEREx acquires a detail yet wide ranging picture of what's 232 00:12:02.440 --> 00:12:03.679 there and what state it's in. 233 00:12:03.799 --> 00:12:06.559 That still sounds like a massive technical challenge. How did 234 00:12:06.559 --> 00:12:08.759 the engineers manage to create a system that can look 235 00:12:08.799 --> 00:12:11.240 at the whole sky and filter it into one hundred 236 00:12:11.240 --> 00:12:14.679 and two separate data streams, all while staying cold enough 237 00:12:14.720 --> 00:12:16.200 to even function in the infrared. 238 00:12:16.440 --> 00:12:19.200 It is a technical marvel, and it required overcoming some 239 00:12:19.240 --> 00:12:23.039 significant thermal challenges. Since sphere x is looking for infrared light, 240 00:12:23.080 --> 00:12:26.279 which is essentially heat, the detectors themselves have to be 241 00:12:26.320 --> 00:12:29.679 kept incredibly cold, many degrees below zero, to prevent their 242 00:12:29.679 --> 00:12:32.840 own thermal radiation from drowning out the faint cosmic signal. 243 00:12:33.080 --> 00:12:34.840 Right, it would just be noise, total noise. 244 00:12:35.080 --> 00:12:37.360 But the real innovation is in the filtering mechanism. 245 00:12:37.480 --> 00:12:40.360 Let's detail that. How did they physically achieve one hundred and. 246 00:12:40.360 --> 00:12:44.639 Two channels so to get this massive color spectrum simultaneously 247 00:12:44.679 --> 00:12:48.080 across its wide field of view. The observatory uses six 248 00:12:48.159 --> 00:12:52.159 individual detectors, and here is the clever bit of optical engineering. 249 00:12:53.039 --> 00:12:55.720 Each of those six detectors is paired with a specially 250 00:12:55.759 --> 00:12:59.840 designed filter called a linear variable filter or LVF. 251 00:13:00.080 --> 00:13:02.600 Any or variable filter. Okay, explain that in concrete terms, 252 00:13:02.759 --> 00:13:04.440 what does a gradient filter look like. 253 00:13:05.159 --> 00:13:08.559 Picture a standard camera filter, which usually just blocks all 254 00:13:08.679 --> 00:13:11.879 light except for one specific color. Okay, The CRX filter 255 00:13:12.000 --> 00:13:15.039 is different. Imagine a narrow rectangle of glass where the 256 00:13:15.080 --> 00:13:18.320 color it transmits changes continuously along its length, kind of 257 00:13:18.360 --> 00:13:21.039 like a smooth rainbow or a gradient. At one end, 258 00:13:21.120 --> 00:13:23.360 it might only let through light at one micron, which 259 00:13:23.399 --> 00:13:26.799 is near infrared. Halfway down it might let through three microns, 260 00:13:26.799 --> 00:13:30.159 which is mid infrared, and at the far end five microns. 261 00:13:30.240 --> 00:13:32.960 Ah. So the filter's properties actually change depending on where 262 00:13:32.960 --> 00:13:33.600 the light hits it. 263 00:13:34.000 --> 00:13:36.600 Exactly as the light from the sky passes through the 264 00:13:36.639 --> 00:13:39.879 telescope and hits the detector, the light falling on different 265 00:13:39.879 --> 00:13:44.519 physical locations of that detector is simultaneously measuring a different wavelength. 266 00:13:45.039 --> 00:13:47.159 The light that hits the left side the detector is 267 00:13:47.159 --> 00:13:49.559 filtered differently than the light that hits the right side. 268 00:13:49.960 --> 00:13:54.519 This gradient allows each detector to simultaneously measure seventeen distinct 269 00:13:54.679 --> 00:13:56.240 colors or wavelength bands. 270 00:13:56.919 --> 00:14:00.600 That makes them add very clear but incredibly efficient detectors. 271 00:14:01.240 --> 00:14:05.919 Times seventeen distinct simultaneous spectral bands per detector gives you 272 00:14:05.960 --> 00:14:07.279 the grand total of one hundred and two. 273 00:14:07.399 --> 00:14:07.799 That's it. 274 00:14:08.000 --> 00:14:10.279 So every time SPHEREx takes a snapshot of a tiny 275 00:14:10.279 --> 00:14:12.919 patch of sky, it's actually generating one hundred and two 276 00:14:13.000 --> 00:14:15.840 separate measurements of spectral intensity for that one patch. 277 00:14:15.960 --> 00:14:19.120 Correct, every all sky map SPHEREx produces isn't just one file. 278 00:14:19.279 --> 00:14:22.440 It's one hundred and two separate, highly precise maps, each 279 00:14:22.480 --> 00:14:25.360 one telling a different, unique story about the structure and 280 00:14:25.440 --> 00:14:28.480 content of the universe at a different spectral depth. And 281 00:14:28.559 --> 00:14:31.399 this high sampling rate one hundred and two channels is 282 00:14:31.440 --> 00:14:34.080 what sets it so far apart from its predecessors, which 283 00:14:34.159 --> 00:14:36.159 might have used only three or four broad bands. 284 00:14:36.360 --> 00:14:40.159 Okay, now let's talk logistics. How does this system, this 285 00:14:40.320 --> 00:14:44.919 cosmic barcode scanner, manage to systematically cover the entire sky 286 00:14:45.480 --> 00:14:46.879 so quickly and precisely. 287 00:14:47.000 --> 00:14:50.320 It all relies on a very carefully maintained orbit and 288 00:14:50.399 --> 00:14:54.440 a systematic scanning pattern. SPHEREx is orbiting Earth in what's 289 00:14:54.440 --> 00:14:57.159 called a polar orbit. It travels from north to south 290 00:14:57.240 --> 00:14:59.559 passing over the poles about fourteen and a half times 291 00:14:59.559 --> 00:15:03.240 every day, and during those orbits, it points its gaze 292 00:15:03.240 --> 00:15:05.600 slightly away from the Earth in the sun, and it 293 00:15:05.679 --> 00:15:08.360 captures a specific narrow strip of the sky. 294 00:15:08.799 --> 00:15:12.320 So I'm picturing it essentially painting a long circular swath 295 00:15:12.360 --> 00:15:14.639 of the sky with every single orbit. 296 00:15:14.720 --> 00:15:16.840 That's a perfect way to put it. Each day it 297 00:15:16.879 --> 00:15:20.120 captures about three allows and six hundred individual images along 298 00:15:20.120 --> 00:15:22.519 one of these circular strips. But here's the key to 299 00:15:22.559 --> 00:15:25.440 getting full coverage. Because the Earth is also moving around 300 00:15:25.440 --> 00:15:28.679 the Sun, the telescope's line of sight gradually shifts relative 301 00:15:28.720 --> 00:15:31.360 to the distant stars. The strip of sky at views 302 00:15:31.360 --> 00:15:33.320 on day one is slightly different from the strip it 303 00:15:33.399 --> 00:15:35.440 views on day ten or day ninety. 304 00:15:36.000 --> 00:15:39.639 That gradual systematic shift must eventually guarantee a full sweep. 305 00:15:39.840 --> 00:15:43.799 It does after six months of continuous systematic scanning along 306 00:15:43.840 --> 00:15:48.039 these slightly shifting strips. This gradual progression allows the observatory 307 00:15:48.080 --> 00:15:51.399 to view space in every direction. It captures the entire 308 00:15:51.559 --> 00:15:53.000 three hundred and sixty degrees of. 309 00:15:53.000 --> 00:15:55.320 The sky, and then it just starts over, and then as. 310 00:15:55.159 --> 00:15:58.120 The orbital geometry repeats itself, it starts over again. For 311 00:15:58.159 --> 00:16:01.159 the second stand ensuring they collect those or repeated exposures. 312 00:16:01.200 --> 00:16:04.840 We talked about that repetitive systematic coverage is what guarantees 313 00:16:04.919 --> 00:16:09.000 that sensitivity boost. But let's talk about the real revolutionary leap. 314 00:16:09.120 --> 00:16:12.519 This detailed spectral data enables the jump from a two 315 00:16:12.600 --> 00:16:16.159 dimensional map of the cosmos to a complete three D atlas. 316 00:16:16.440 --> 00:16:18.960 This is perhaps the most critical scientific application of those 317 00:16:19.000 --> 00:16:22.679 one hundred and two spectral bands. Other powerful observatories have 318 00:16:22.720 --> 00:16:25.759 been mapping the positions of galaxies for years, but generally 319 00:16:25.799 --> 00:16:28.200 those maps are two dimensional. We know where they are 320 00:16:28.200 --> 00:16:30.919 in the sky they're celestial coordinates, but we don't know 321 00:16:30.960 --> 00:16:33.559 precisely how far away they are. They're just flattened onto 322 00:16:33.600 --> 00:16:34.159 a sphere. 323 00:16:34.200 --> 00:16:36.240 So if I see two galaxies that look like they're 324 00:16:36.320 --> 00:16:38.200 right next to each other on the map, I have 325 00:16:38.279 --> 00:16:40.879 no idea if they are actually cosmic neighbors, or if 326 00:16:40.879 --> 00:16:43.759 one is ten billion light years behind the other just 327 00:16:43.879 --> 00:16:45.240 lined up by chance in our. 328 00:16:45.159 --> 00:16:49.519 Field of view Exactly That missing depth is the distance component, 329 00:16:50.000 --> 00:16:53.320 and SPHEREx is one O two channel multi wavelength view 330 00:16:53.840 --> 00:16:57.480 provides the solution through what's called cosmological red shift. 331 00:16:57.720 --> 00:17:00.039 Okay, let's elaborate on this because This is where the 332 00:17:00.039 --> 00:17:03.279 precision of those hundred two channels really proves its value. 333 00:17:03.679 --> 00:17:05.960 How does measuring one hundred and two points across the 334 00:17:05.960 --> 00:17:07.759 infrared spectrum give them the distance? 335 00:17:08.079 --> 00:17:11.160 Well, when a galaxy emits light, that light has specific 336 00:17:11.359 --> 00:17:15.799 recognizable spectral features, emission lines and absorption lines created by 337 00:17:15.799 --> 00:17:16.720 the elements within it. 338 00:17:16.799 --> 00:17:18.599 Okay, like a fingerprint, perfect. 339 00:17:18.319 --> 00:17:21.720 Fingerprint, But because the universe is expanding, the farther away 340 00:17:21.759 --> 00:17:24.000 a galaxy is, the faster it appears to be moving 341 00:17:24.039 --> 00:17:27.640 away from us. This rapid motion stretches the light waves, 342 00:17:27.960 --> 00:17:31.680 shifting those recognizable spectral features towards the red or infrared 343 00:17:31.759 --> 00:17:33.759 end of the spectrum. This is redshift. 344 00:17:34.000 --> 00:17:35.960 So the farther away the galaxy, the more the light 345 00:17:36.000 --> 00:17:38.759 is stretched, and the deeper into the infrared, SPHEREx will 346 00:17:38.799 --> 00:17:41.440 see those fingerprint features precisely. 347 00:17:41.960 --> 00:17:46.400 Now. The older, simpler infrared surveys like ys used only 348 00:17:46.440 --> 00:17:49.440 four broad channels. That's enough to guess the red shift, 349 00:17:49.640 --> 00:17:52.240 but it's often prone to errors, especially when you're trying 350 00:17:52.279 --> 00:17:56.359 to pin down the distance to hundreds of millions of objects. 351 00:17:55.960 --> 00:17:57.880 So it is more of an estimate, a very rough one. 352 00:17:57.960 --> 00:18:01.880 Yes, SPHEREx by measuring one hundred and two specific points 353 00:18:02.359 --> 00:18:06.119 allows astronomers to do much more accurate spectral curve fitting. 354 00:18:06.400 --> 00:18:08.960 They can map the precise shape of the spectral curve 355 00:18:09.039 --> 00:18:10.119 of that galaxy's light. 356 00:18:10.319 --> 00:18:12.640 That ability to measure the curve with high resolution the 357 00:18:12.640 --> 00:18:15.799 one hundred and two photometric bands must allow them to 358 00:18:15.839 --> 00:18:18.759 pin down the distance with far greater certainty than before 359 00:18:19.000 --> 00:18:19.519 it does. 360 00:18:19.720 --> 00:18:23.319 They can identify specific spectral breaks and molecular features and 361 00:18:23.359 --> 00:18:27.480 then measure exactly how far they've been redshifted. This allows 362 00:18:27.519 --> 00:18:31.200 them to determine the distance to hundreds of millions of galaxies. 363 00:18:31.480 --> 00:18:34.680 Converting that two D celestial map into a full three 364 00:18:34.799 --> 00:18:38.599 D map of the universe, it provides accurate depth and volume, 365 00:18:38.920 --> 00:18:42.359 and that three D distribution how galaxies are clustered and 366 00:18:42.400 --> 00:18:46.400 distributed across billions of cubic light years that holds the 367 00:18:46.480 --> 00:18:49.839 key to unlocking the deepest mysteries of the universe's past. 368 00:18:50.079 --> 00:18:53.279 That transition to the high fidelity three D map really 369 00:18:53.319 --> 00:18:56.559 sets the stage for the enormous scientific goals of this mission. 370 00:18:56.880 --> 00:18:59.240 When you look at the name again spectrophotometer for the 371 00:18:59.279 --> 00:19:02.559 history of the Universe, epoch of realization and ices explore, 372 00:19:02.960 --> 00:19:05.720 it's clear this telescope is targeting cosmic history across the 373 00:19:05.839 --> 00:19:08.160 entire age of the cosmos. So let's tackle the most 374 00:19:08.200 --> 00:19:09.039 dramatic one first. 375 00:19:09.079 --> 00:19:11.680 We have to start with the most distant and complex target, 376 00:19:11.720 --> 00:19:14.640 which is literally at the very very beginning of time goal. 377 00:19:14.480 --> 00:19:18.160 Number one, gaining insights into the epoch of cosmic inflation. 378 00:19:18.519 --> 00:19:21.039 This is the cosmological reason they need that three D 379 00:19:21.160 --> 00:19:25.000 map of hundreds of millions of galaxies. Inflation is a 380 00:19:25.039 --> 00:19:28.880 theory describing an extraordinarily rapid and massive expansion of the 381 00:19:28.960 --> 00:19:31.559 universe in the earliest moments of existence. 382 00:19:31.119 --> 00:19:34.160 And the timing is just mind bendingly short. 383 00:19:34.359 --> 00:19:38.519 It's almost incomprehensible. The sources detail the timing of this event. 384 00:19:38.960 --> 00:19:41.400 It occurred in the first billionth of a trillion of 385 00:19:41.440 --> 00:19:43.039 a trillionth of a second after the. 386 00:19:43.039 --> 00:19:45.079 Big Bang, a fraction of a fraction of a fraction 387 00:19:45.119 --> 00:19:47.960 of a second, and yet it determined everything we see today. 388 00:19:48.559 --> 00:19:52.559 During that infinitesimally brief moment, the universe expanded by a 389 00:19:52.599 --> 00:19:57.119 factor of a trillion trillion fold. This dramatic burst solved 390 00:19:57.200 --> 00:20:00.920 several long standing cosmological puzzles, but the evidence for it 391 00:20:00.960 --> 00:20:03.920 is incredibly difficult to find because it happened so quickly 392 00:20:04.000 --> 00:20:04.680 and so early. 393 00:20:05.359 --> 00:20:07.440 So if this event was so fast and happened so 394 00:20:07.519 --> 00:20:09.680 long ago, how can it tell usco Blanch in twenty 395 00:20:09.720 --> 00:20:12.640 twenty five possibly find the evidence for it billions of 396 00:20:12.680 --> 00:20:15.680 years later. What's the link between Spherx's three D map 397 00:20:15.920 --> 00:20:17.119 and that moment of inflation? 398 00:20:17.400 --> 00:20:21.519 The link is quantum mechanics and gravity. According to inflation theory, 399 00:20:21.640 --> 00:20:25.200 the universe was not perfectly uniform before, during, or after 400 00:20:25.359 --> 00:20:30.240 that rapid expansion. The quantum fluctuations, these tiny random variations 401 00:20:30.279 --> 00:20:33.480