1 00:00:02,633 --> 00:00:06,867 Narrator: THE SUN, OUR NUCLEAR POWERHOUSE. 2 00:00:07,833 --> 00:00:16,933 OUR STAR, ITS LIGHT POWERS OUR WORLD...AND US. 3 00:00:16,967 --> 00:00:20,333 WITHOUT LIGHT, WE WOULD NOT BE ALIVE. 4 00:00:22,500 --> 00:00:25,700 Narrator: STARTING DEEP INSIDE THE SUN, 5 00:00:25,733 --> 00:00:27,933 WE FOLLOW THE BRUTAL JOURNEY 6 00:00:27,967 --> 00:00:33,267 OF A SINGLE, TINY PACKAGE OF LIGHT -- A PHOTON. 7 00:00:33,300 --> 00:00:36,467 THE RIDE THAT ANY PHOTON TAKES TO GET TO MY EYES 8 00:00:36,500 --> 00:00:39,100 WHEN I LOOK UP AT THE SUN IS AN AMAZING ONE. 9 00:00:39,133 --> 00:00:41,600 Narrator: FROM ITS ANCIENT BIRTH IN THE SUN'S CORE 10 00:00:41,633 --> 00:00:43,667 TO ITS ESCAPE FROM THE SURFACE. 11 00:00:46,133 --> 00:00:47,767 Thaller: THE LIGHT REACHING ME FROM THE SUN 12 00:00:47,800 --> 00:00:50,533 WAS PRODUCED BEFORE THERE WAS EVEN HUMAN CIVILIZATION. 13 00:00:50,567 --> 00:00:51,833 IT'S AN INCREDIBLE IDEA. 14 00:00:53,800 --> 00:00:55,267 Narrator: JOIN OUR PHOTON 15 00:00:55,300 --> 00:00:58,367 ON ITS INCREDIBLE MILLION-YEAR JOURNEY 16 00:00:58,400 --> 00:01:03,500 THROUGH THE MOST HOSTILE ENVIRONMENT IN THE SOLAR SYSTEM 17 00:01:03,533 --> 00:01:07,067 TO BRING LIGHT AND LIFE TO EARTH. 18 00:01:10,400 --> 00:01:13,367 -- Captions by VITAC -- www.vitac.com 19 00:01:13,400 --> 00:01:16,433 CAPTIONS PAID FOR BY DISCOVERY COMMUNICATIONS 20 00:01:23,733 --> 00:01:28,500 THE UNIVERSE, HOME TO BILLIONS OF GALAXIES... 21 00:01:30,567 --> 00:01:33,500 ...EACH MADE OF BILLIONS OF STARS. 22 00:01:36,667 --> 00:01:41,067 AND, IN AN UNREMARKABLE CORNER OF OUR GALAXY, THE MILKY WAY, 23 00:01:41,067 --> 00:01:44,833 LIES THE SUN, OUR CLOSEST STAR... 24 00:01:47,233 --> 00:01:51,433 ...A DAZZLING SPHERE OF INTENSE LIGHT, 25 00:01:51,467 --> 00:01:53,167 TOO BRIGHT FOR THE NAKED EYE. 26 00:01:55,133 --> 00:02:00,500 BUT STRIP AWAY THAT GLARE, AND THE SUN TRANSFORMS 27 00:02:00,533 --> 00:02:02,500 INTO A GIANT BALL 28 00:02:02,533 --> 00:02:07,333 OF SUPER HEATED GAS DOMINATING OUR COSMIC STAGE. 29 00:02:10,967 --> 00:02:12,967 Gilbert: THE SUN IS REALLY THE STAR OF THE SHOW. 30 00:02:13,067 --> 00:02:16,533 THE SUN IS THE PARENT OF THE WHOLE SOLAR SYSTEM. 31 00:02:16,567 --> 00:02:20,067 IT PROVIDES ITS CHILDREN, THE PLANETS, 32 00:02:20,100 --> 00:02:21,533 WITH EVERYTHING THEY NEED. 33 00:02:21,567 --> 00:02:25,533 WE DEPEND ON THE SUN FOR ENERGY, FOR LIGHT, FOR WARMTH. 34 00:02:25,567 --> 00:02:28,167 WE WOULD NOT EXIST WITHOUT THE SUN. 35 00:02:32,167 --> 00:02:34,933 Narrator: THE SUN GENERATES HEAT AND LIGHT, 36 00:02:34,967 --> 00:02:37,600 THE ENERGY SOURCE FOR ALL LIFE ON EARTH. 37 00:02:37,633 --> 00:02:41,600 Thaller: ALL OF THE ENERGY THAT MY BODY USES, 38 00:02:41,633 --> 00:02:43,933 LITERALLY WHAT I'M DOING TO TALK TO YOU RIGHT NOW, 39 00:02:43,967 --> 00:02:45,367 CAME FROM THE SUN. 40 00:02:45,400 --> 00:02:48,400 THE SUN TRULY IS THE CREATOR OF ALL OF THE LIFE AROUND US. 41 00:02:50,067 --> 00:02:52,767 Narrator: THE SUN IS A CONSTANTLY EXPLODING 42 00:02:52,800 --> 00:02:56,167 NUCLEAR BOMB, VIOLENT AND ESSENTIAL. 43 00:02:58,600 --> 00:03:02,467 Krauss: OUR ENTIRE EXISTENCE IS POWERED BY THE ENERGY 44 00:03:02,500 --> 00:03:04,500 EMITTED IN THOSE NUCLEAR REACTIONS IN THE SUN. 45 00:03:04,533 --> 00:03:07,600 WE ARE HERE BECAUSE OF THE LIGHT FROM THE SUN. 46 00:03:07,633 --> 00:03:09,767 WE ARE HERE BECAUSE OF THOSE NUCLEAR REACTIONS, 47 00:03:09,800 --> 00:03:12,433 AND NO ASPECT OF OUR EXISTENCE COULD PERSIST 48 00:03:12,467 --> 00:03:13,700 IF IT WASN'T THERE. 49 00:03:16,467 --> 00:03:19,233 Narrator: LIGHT IS ONE OF THE BASIC BUILDING BLOCKS 50 00:03:19,267 --> 00:03:20,300 OF THE UNIVERSE. 51 00:03:26,633 --> 00:03:29,233 Gilbert: I FIND LIGHT TO BE PROBABLY 52 00:03:29,267 --> 00:03:30,900 THE MOST AMAZING THING IN THE UNIVERSE. 53 00:03:30,933 --> 00:03:32,933 IT'S SO IMPORTANT IN EVERYTHING. 54 00:03:32,967 --> 00:03:35,267 I MEAN, IT'S EVERYTHING. IT'S EVERYWHERE. 55 00:03:35,300 --> 00:03:38,800 SO, IT'S SUCH A FUNDAMENTAL PART OF EVERYTHING THAT EXISTS. 56 00:03:38,833 --> 00:03:43,933 Narrator: FUNDAMENTAL AND FAST. 57 00:03:43,967 --> 00:03:46,167 THE FASTEST THING IN THE COSMOS... 58 00:03:48,133 --> 00:03:52,167 ...TRAVELING AT 186,000 MILES PER SECOND. 59 00:03:54,300 --> 00:03:56,767 THE SUN IS ABOUT 93 MILLION MILES AWAY FROM US. 60 00:03:56,800 --> 00:03:58,933 SO, GOING AT 186,000 MILES PER SECOND, 61 00:03:58,967 --> 00:04:00,133 THAT'S ABOUT EIGHT MINUTES. 62 00:04:00,167 --> 00:04:02,067 Narrator: BUT THOSE EIGHT MINUTES 63 00:04:02,067 --> 00:04:05,667 ARE JUST THE BRIEF LAST LEG OF ITS INCREDIBLE JOURNEY. 64 00:04:11,700 --> 00:04:14,433 IT MAY HAVE TAKEN THE LIGHT AS MUCH AS A MILLION YEARS 65 00:04:14,467 --> 00:04:16,833 TO ESCAPE FROM THE SUN'S RAGING INTERIOR... 66 00:04:20,500 --> 00:04:23,267 ...WHICH MEANS THE LIGHT WE'RE SEEING RIGHT NOW 67 00:04:23,300 --> 00:04:25,500 WAS CREATED LONG BEFORE 68 00:04:25,533 --> 00:04:27,667 OUR ANCESTORS LEFT THE PLAINS OF AFRICA. 69 00:04:31,067 --> 00:04:32,833 Krauss: WHEN I FIRST LEARNED THIS FACT, 70 00:04:32,867 --> 00:04:34,867 I WAS ALREADY A PRACTICING SCIENTIST. 71 00:04:34,900 --> 00:04:36,867 I HAD NEVER REALLY THOUGHT ABOUT THAT, 72 00:04:36,900 --> 00:04:39,433 AND ON FIRST GLANCE, IT JUST BLEW ME AWAY. 73 00:04:39,467 --> 00:04:41,600 Thaller: RIGHT NOW THE LIGHT REACHING ME FROM THE SUN 74 00:04:41,633 --> 00:04:44,533 WAS PRODUCED BEFORE THERE WAS EVEN HUMAN CIVILIZATION. 75 00:04:44,567 --> 00:04:46,900 AND YET, THE MINUTE IT GETS TO THE SURFACE OF THE SUN, 76 00:04:46,933 --> 00:04:50,067 IT RACES AWAY AND IS HERE EIGHT MINUTES AFTER THAT. 77 00:04:50,067 --> 00:04:53,200 IT'S AN INCREDIBLE IDEA. 78 00:04:53,233 --> 00:04:56,133 THE RIDE THAT ANY PHOTON TAKES TO GET TO MY EYES 79 00:04:56,167 --> 00:04:59,600 WHEN I LOOK UP AT THE SUN IS AN AMAZING ONE. 80 00:04:59,633 --> 00:05:03,067 Narrator: THAT RIDE STARTS DEEP IN THE BELLY OF OUR STAR. 81 00:05:05,067 --> 00:05:08,167 IF WE COULD OPEN UP THE SUN, 82 00:05:08,200 --> 00:05:11,833 WE'D SEE LAYERS OF DENSE HYDROGEN GAS 83 00:05:11,867 --> 00:05:15,433 HUNDREDS OF THOUSANDS OF MILES DEEP. 84 00:05:15,467 --> 00:05:20,500 AND AT ITS CENTER, THE CORE, THE SUN GIVES BIRTH TO LIGHT... 85 00:05:25,833 --> 00:05:28,367 ...FORGED IN ONE OF THE MOST VIOLENT REACTIONS 86 00:05:28,400 --> 00:05:32,167 IN THE UNIVERSE, NUCLEAR FUSION. 87 00:05:38,533 --> 00:05:41,700 THE SPECIFIC NUCLEAR REACTION THAT POWERS THE SUN IS FUSION, 88 00:05:41,733 --> 00:05:43,700 FUSION OF HYDROGEN INTO HELIUM. 89 00:05:43,733 --> 00:05:46,267 YOU TAKE TWO HYDROGEN ATOMS, YOU RAM THEM TOGETHER, 90 00:05:46,300 --> 00:05:48,667 AND WHAT'S LEFT OVER IS A HELIUM ATOM. 91 00:05:48,700 --> 00:05:50,467 Narrator: IT SOUNDS SIMPLE ENOUGH, 92 00:05:50,500 --> 00:05:52,767 BUT IT'S NOT. 93 00:05:52,800 --> 00:05:55,300 IT'S ACTUALLY HARD TO GET TWO ATOMS TO FUSE. 94 00:05:55,333 --> 00:05:57,067 TWO PHOTONS HAVE THE SAME CHARGE. 95 00:05:57,100 --> 00:05:59,800 THEY'RE BOTH POSITIVELY CHARGED. THEY WANT TO REPEL EACH OTHER. 96 00:06:02,567 --> 00:06:04,933 Krauss: PROTONS DON'T LIKE TO GET CLOSE TOGETHER. 97 00:06:04,967 --> 00:06:07,300 THEY HAVE TO COME TOGETHER WITH A HUGE AMOUNT 98 00:06:07,333 --> 00:06:09,600 OF ENERGY OR VELOCITY 99 00:06:09,633 --> 00:06:11,633 TO GET CLOSE ENOUGH TO BEGIN TO FUSE, 100 00:06:11,667 --> 00:06:14,567 AND THAT'S VERY, VERY RARE. 101 00:06:14,600 --> 00:06:16,767 Narrator: TO FORCE PROTONS TOGETHER 102 00:06:16,800 --> 00:06:19,900 TAKES IMMENSE AMOUNTS OF HEAT AND PRESSURE... 103 00:06:21,900 --> 00:06:25,867 ...GENERATED BY THE INVISIBLE HAND OF GRAVITY. 104 00:06:25,900 --> 00:06:29,500 THE SUN CONTAINS 99.8% OF ALL THE MATTER 105 00:06:29,533 --> 00:06:31,067 IN THE SOLAR SYSTEM. 106 00:06:33,633 --> 00:06:35,933 THAT'S A LOT OF MASS. 107 00:06:35,967 --> 00:06:38,800 ALL THAT MASS PULLS THE SUN TOGETHER 108 00:06:38,833 --> 00:06:41,833 WITH UNIMAGINABLE GRAVITATIONAL FORCE. 109 00:06:44,233 --> 00:06:46,300 Thaller: WITH GRAVITY CRUSHING THINGS DOWN, 110 00:06:46,333 --> 00:06:50,800 THINGS GET CLOSE ENOUGH TOGETHER AND NUCLEAR FUSION HAPPENS. 111 00:06:50,833 --> 00:06:54,100 Narrator: IN THIS NUCLEAR COMPACTOR, 112 00:06:54,133 --> 00:06:55,767 HYDROGEN ATOMS SLAM TOGETHER 113 00:06:55,800 --> 00:07:00,400 100 MILLION QUADRILLION QUADRILLION TIMES EACH SECOND. 114 00:07:04,633 --> 00:07:10,133 SOME OF THESE COLLISIONS ARE SO POWERFUL THAT ATOMS FUSE, 115 00:07:10,167 --> 00:07:12,100 RELEASING ENERGY. 116 00:07:12,133 --> 00:07:15,933 WHEN THE PROTONS COME TOGETHER TO BIND TOGETHER, 117 00:07:15,967 --> 00:07:17,600 THEY LOSE A LITTLE BIT OF MASS, 118 00:07:17,633 --> 00:07:19,933 AND THAT MASS GETS CONVERTED INTO ENERGY. 119 00:07:19,967 --> 00:07:22,600 AND EVERY SECOND OF EVERY DAY, 120 00:07:22,633 --> 00:07:28,500 ABOUT FIVE MILLION TONS OF STUFF IS BEING CONVERTED TO ENERGY. 121 00:07:28,533 --> 00:07:30,167 IT'S AMAZING. 122 00:07:35,367 --> 00:07:39,067 Narrator: EACH COLLISION CREATES A TINY BURST OF ENERGY, 123 00:07:39,067 --> 00:07:45,067 A PACKET OF LIGHT IMPOSSIBLY SMALL AND INCREDIBLY POWERFUL. 124 00:07:47,733 --> 00:07:51,833 SOMEHOW, OUR PHOTON WILL DELIVER ITS ENERGY TO EARTH 125 00:07:51,867 --> 00:07:57,067 WHERE IT WILL POWER THE PLANET AND MAKE LIFE POSSIBLE. 126 00:07:57,100 --> 00:08:01,400 BUT RIGHT NOW IT'S NOTHING LIKE THE LIGHT WE SEE. 127 00:08:01,433 --> 00:08:06,433 IT HAS MASSIVE AMOUNTS OF ENERGY, AND IT'S DEADLY. 128 00:08:20,767 --> 00:08:25,267 Narrator: THE LIGHT WE SEE FROM OUR STAR IS OLD... 129 00:08:25,300 --> 00:08:27,100 MUCH OLDER THAN THE EIGHT MINUTES IT TAKES 130 00:08:27,133 --> 00:08:29,067 TO GET FROM THE SUN TO EARTH. 131 00:08:31,433 --> 00:08:35,933 THAT SHORT LEAP ACROSS SPACE IS THE END OF A LONG, HARD JOURNEY 132 00:08:35,967 --> 00:08:38,267 THAT STARTS DEEP INSIDE OUR SUN. 133 00:08:38,300 --> 00:08:39,933 Kaku: WHEN WE LOOK AT THE SUN, 134 00:08:39,967 --> 00:08:43,600 WE SAY, "HOW BEAUTIFUL, HOW ELEGANT, AND HOW SIMPLE." 135 00:08:43,633 --> 00:08:44,733 LIGHT IS FORMED IN THE SUN, 136 00:08:44,767 --> 00:08:47,600 AND IT SHINES AND LIGHTS UP OUR WORLD. 137 00:08:47,633 --> 00:08:49,067 WELL, NOT SO FAST. 138 00:08:49,100 --> 00:08:50,967 IT'S ACTUALLY VERY COMPLEX. 139 00:08:53,800 --> 00:08:54,933 Narrator: THE JOURNEY STARTS 140 00:08:54,967 --> 00:08:57,600 IN THE IMMENSE HEAT OF THE SUN'S CORE. 141 00:09:03,367 --> 00:09:07,067 CRUSHED TOGETHER BY THE SUN'S ENORMOUS GRAVITY, 142 00:09:07,067 --> 00:09:09,833 ATOMS SMASH INTO EACH OTHER AND FUSE... 143 00:09:11,367 --> 00:09:16,667 ...RELEASING A TINY PACKET OF ENERGY, PHOTON OF LIGHT... 144 00:09:18,633 --> 00:09:22,867 ...FAR SMALLER THAN AN ATOM WITH NO MASS. 145 00:09:22,900 --> 00:09:25,767 PHOTONS TRAVEL FASTER THAN ANYTHING ELSE, 146 00:09:25,800 --> 00:09:30,500 AND THEY NEVER STOP MOVING. 147 00:09:35,233 --> 00:09:38,933 PHOTONS DON'T JUST COME FROM THE CORE OF STARS. 148 00:09:41,100 --> 00:09:42,433 Oluseyi: SO, WHERE DOES LIGHT COME FROM? 149 00:09:42,467 --> 00:09:45,300 THE SHORT ANSWER IS, MATTER MAKES IT, 150 00:09:45,333 --> 00:09:47,167 AND THE AMOUNT OF LIGHT THAT IT CREATES 151 00:09:47,200 --> 00:09:48,467 DEPENDS ON ITS TEMPERATURE. 152 00:09:50,400 --> 00:09:52,267 Narrator: EVERY PIECE OF MATTER IN THE UNIVERSE 153 00:09:52,300 --> 00:09:54,767 ABOVE ABSOLUTE ZERO DEGREES 154 00:09:54,800 --> 00:09:57,600 PRODUCES LIGHT, INCLUDING HUMANS. 155 00:09:59,300 --> 00:10:01,800 Filippenko: WE HUMANS ARE EMITTING LIGHT ALL THE TIME 156 00:10:01,833 --> 00:10:05,233 BECAUSE WE'RE ALIVE, WE'RE WARM, WE'RE NOT AT A ZERO TEMPERATURE. 157 00:10:05,267 --> 00:10:08,567 SO, IN FACT WE ARE EMITTING INFRARED RADIATION, 158 00:10:08,600 --> 00:10:10,600 OFTEN CALLED HEAT RADIATION. 159 00:10:10,633 --> 00:10:13,000 BUT ALL MATTER EMITS LIGHT. 160 00:10:13,033 --> 00:10:16,233 EVEN SOMEONE AS COOL AS ME, I'M CREATING LIGHT RIGHT NOW. 161 00:10:20,033 --> 00:10:21,567 Narrator: THE LIGHT WE SEE 162 00:10:21,600 --> 00:10:23,900 CAN BE SPLIT INTO THE COLORS OF THE RAINBOW. 163 00:10:23,933 --> 00:10:26,433 EACH COLOR IS PHOTONS OF LIGHT 164 00:10:26,467 --> 00:10:29,333 WITH SLIGHTLY DIFFERENT AMOUNTS OF ENERGY. 165 00:10:32,300 --> 00:10:33,667 AND WHAT WE CAN SEE 166 00:10:33,700 --> 00:10:35,967 IS ONLY A FRACTION OF THE LIGHT SPECTRUM. 167 00:10:38,133 --> 00:10:40,433 OUR EYES ARE ACTUALLY IMPERFECT DETECTORS. 168 00:10:40,467 --> 00:10:41,733 WE KNOW ABOUT VISIBLE LIGHT, 169 00:10:41,767 --> 00:10:44,033 THE TYPE OF LIGHT THAT OUR EYES ARE SENSITIVE TO, 170 00:10:44,067 --> 00:10:45,800 BUT THAT'S ONLY A SMALL RANGE OF ENERGIES. 171 00:10:45,833 --> 00:10:50,433 LIGHT COMES AT HIGHER AND LOWER ENERGIES THAN WE CAN DETECT. 172 00:10:50,467 --> 00:10:51,867 Narrator: USING SPECIAL CAMERAS, 173 00:10:51,900 --> 00:10:55,500 WE CAN SEE THE INFRARED LIGHT THAT HUMANS EMIT. 174 00:10:57,100 --> 00:10:58,933 THIS INFRARED LIGHT 175 00:10:58,967 --> 00:11:02,067 HAS LESS ENERGY THAN THE VISIBLE LIGHT WE SEE. 176 00:11:05,400 --> 00:11:10,100 SOME LIGHT IS TOO ENERGETIC TO SEE, 177 00:11:10,133 --> 00:11:14,167 LIKE ULTRAVIOLETS, X-RAYS, AND GAMMA RAYS. 178 00:11:19,667 --> 00:11:25,167 THE VAST, HOT SUN GENERATES ALL FORMS OF LIGHT. 179 00:11:25,200 --> 00:11:28,767 BUT IN THE NUCLEAR FURNACE OF THE SUN'S CORE, 180 00:11:28,800 --> 00:11:32,700 EVERY PHOTON STARTS OUT AS A GAMMA RAY, 181 00:11:32,733 --> 00:11:37,433 THE MOST ENERGETIC FORM OF LIGHT IN THE UNIVERSE. 182 00:11:37,467 --> 00:11:38,600 Krauss: AND WHEN A NUCLEAR REACTION HAPPENS, 183 00:11:38,633 --> 00:11:40,933 IT EMITS AN AMAZING AMOUNT OF ENERGY, 184 00:11:40,967 --> 00:11:43,633 THE ENERGY MUCH, MUCH BIGGER THAN VISIBLE LIGHT -- 185 00:11:43,667 --> 00:11:46,200 GAMMA RAYS, WE CALL THEM. 186 00:11:46,233 --> 00:11:48,600 LITERALLY ALMOST A MILLION TIMES 187 00:11:48,633 --> 00:11:53,433 OR AT LEAST 10,000 TIMES THE ENERGY OF THE LIGHT WE SEE. 188 00:11:53,467 --> 00:11:58,400 Narrator: GAMMA RAYS CAN TRANSFORM AND EVEN KILL. 189 00:11:58,433 --> 00:12:00,067 THERE'S A REASON WHY GAMMA RAYS 190 00:12:00,067 --> 00:12:01,833 TURNED BRUCE BANNER INTO THE HULK. 191 00:12:01,867 --> 00:12:04,500 GAMMA RAYS ARE A VERY DANGEROUS FORM OF LIGHT. 192 00:12:04,533 --> 00:12:06,167 THEY CAN TRAVEL INTO YOUR BODY 193 00:12:06,200 --> 00:12:07,767 AND WHEN THEY INTERACT WITH THE MATTER, 194 00:12:07,800 --> 00:12:10,633 THEY CAN BREAK APART ATOMS. 195 00:12:10,667 --> 00:12:12,433 Narrator: FORTUNATELY FOR US, 196 00:12:12,467 --> 00:12:16,433 OUR GAMMA-RAY PHOTON CAN'T HEAD STRAIGHT OUT OF THE SUN. 197 00:12:23,467 --> 00:12:26,567 Filippenko: IF THE SUN WERE NOT THIS HOT BALL OF GAS, 198 00:12:26,600 --> 00:12:28,433 THEN UPON BEING CREATED, 199 00:12:28,467 --> 00:12:31,933 A PHOTON WOULD IMMEDIATELY ESCAPE FROM THE SUN 200 00:12:31,967 --> 00:12:33,400 AND IT WOULD BE A GAMMA-RAY PHOTON, 201 00:12:33,433 --> 00:12:38,467 A VERY ENERGETIC PHOTON, NOT VERY GOOD FOR LIFE ON EARTH. 202 00:12:38,500 --> 00:12:41,067 Narrator: AFTER ITS BIRTH AS A GAMMA RAY, 203 00:12:41,100 --> 00:12:44,433 OUR PHOTON STARTS TO RACE OUT FROM THE SUN'S CORE 204 00:12:44,467 --> 00:12:45,500 AT THE SPEED OF LIGHT. 205 00:12:49,800 --> 00:12:53,833 BUT IT ENCOUNTERS AN OBSTACLE COURSE OF EPIC PROPORTIONS. 206 00:12:55,633 --> 00:12:58,067 A JOURNEY THAT SHOULD TAKE SECONDS 207 00:12:58,067 --> 00:13:00,333 SLOWS TO A COSMIC CRAWL. 208 00:13:02,833 --> 00:13:07,067 IT TAKES ON AVERAGE ABOUT 100,000 YEARS 209 00:13:07,067 --> 00:13:10,167 FOR A PHOTON TO MAKE IT FROM THE MIDDLE OF THE SUN, 210 00:13:10,200 --> 00:13:12,900 WHERE IT WAS CREATED, TO THE OUTERMOST EDGE, 211 00:13:12,933 --> 00:13:16,233 WHERE IT GETS EMITTED INTO SPACE -- 100,000 YEARS. 212 00:13:16,267 --> 00:13:19,200 IF IT HAD TRAVELED IN A STRAIGHT LINE UNIMPEDED, 213 00:13:19,233 --> 00:13:21,400 IT WOULD HAVE TAKEN TWO SECONDS. 214 00:13:21,433 --> 00:13:24,767 Narrator: WHAT COULD POSSIBLY SLOW A PHOTON 215 00:13:24,800 --> 00:13:28,433 MOVING AT THE SPEED OF LIGHT? 216 00:13:28,467 --> 00:13:36,967 SOMETHING SLAMS ON THE BRAKES -- HUGE, HOT, DENSE. 217 00:13:37,067 --> 00:13:41,900 SO POWERFUL, IT DOESN'T JUST SLOW LIGHT, 218 00:13:41,933 --> 00:13:43,600 IT TRANSFORMS IT. 219 00:13:57,333 --> 00:13:59,200 Narrator: IN THE SUN'S CORE, 220 00:13:59,233 --> 00:14:03,833 NUCLEAR FUSION RELEASES A TINY BUNDLE OF ENERGY... 221 00:14:06,067 --> 00:14:08,067 ...A PHOTON OF LIGHT. 222 00:14:08,967 --> 00:14:13,833 IT RACES OUTWARDS AT 186,000 MILES PER SECOND. 223 00:14:17,233 --> 00:14:19,933 AT THAT SPEED, IT SHOULD TAKE TWO SECONDS 224 00:14:19,967 --> 00:14:23,067 TO TRAVEL THROUGH THE SUN'S INTERIOR TO THE SURFACE. 225 00:14:27,133 --> 00:14:32,100 BUT SOMETHING TURNS SECONDS INTO AN ETERNITY. 226 00:14:32,133 --> 00:14:33,500 THE SUN IS SO DENSE 227 00:14:33,533 --> 00:14:36,100 THAT TO GET THROUGH ALL OF THE DIFFERENT LAYERS OF GAS, 228 00:14:36,133 --> 00:14:38,600 THIS POOR LITTLE PIECE OF LIGHT TAKES HUNDREDS OF THOUSANDS, 229 00:14:38,633 --> 00:14:40,667 IF NOT A MILLION YEARS, TO GET TO THE SURFACE. 230 00:14:44,900 --> 00:14:46,700 Krauss: SO, WHEN YOU'RE LOOKING AT THE SUN, 231 00:14:46,733 --> 00:14:47,933 YOU'RE LOOKING AT THE LIGHT 232 00:14:47,967 --> 00:14:51,267 EMITTED FROM REACTIONS A MILLION YEARS AGO. 233 00:14:51,300 --> 00:14:52,767 Narrator: OUR NEWBORN PHOTON 234 00:14:52,800 --> 00:14:54,600 LEAVES THE CORE AT THE SPEED OF LIGHT 235 00:14:54,633 --> 00:14:57,900 ONLY TO RUN SMACK INTO A DENSE SOUP 236 00:14:57,933 --> 00:15:02,067 OF HYDROGEN ATOMS, A PHOTON'S NIGHTMARE, 237 00:15:02,067 --> 00:15:07,067 THAT STRETCHES FOR OVER 400,000 MILES. 238 00:15:07,100 --> 00:15:09,433 Plait: IF YOU'RE A PHOTON BORN IN THE CENTER OF THE SUN, 239 00:15:09,467 --> 00:15:11,633 YOU HAVE A HECK OF A JOURNEY AHEAD OF YOU. 240 00:15:11,667 --> 00:15:13,067 IT'S ACTUALLY PRETTY HARD 241 00:15:13,067 --> 00:15:15,833 FOR LIGHT GENERATED IN THE CORE OF THE SUN TO GET OUT 242 00:15:15,867 --> 00:15:18,167 BECAUSE THERE'S A LOT OF SUN IN THE WAY, 243 00:15:18,200 --> 00:15:19,667 AND IT'S EXTREMELY DENSE. 244 00:15:19,700 --> 00:15:24,067 Narrator: THE RADIATION ZONE SURROUNDS THE CORE OF THE SUN. 245 00:15:27,067 --> 00:15:29,733 THE ZONE IS MADE OF HYDROGEN GAS, 246 00:15:29,767 --> 00:15:32,067 BUT NOT A GAS AS WE THINK OF IT. 247 00:15:34,467 --> 00:15:37,433 THE SHEER WEIGHT OF ALL THE MATERIAL ABOVE 248 00:15:37,467 --> 00:15:42,800 COMPRESSES THE RADIATION ZONE UNTIL IT'S DENSER THAN LEAD 249 00:15:42,833 --> 00:15:45,167 AND NEARLY IMPOSSIBLE TO PASS THROUGH. 250 00:15:49,567 --> 00:15:51,933 A PHOTON PRODUCED IN THE CENTER OF THE SUN 251 00:15:51,967 --> 00:15:53,833 KNOWS WHERE IT WANTS TO GO. 252 00:15:53,867 --> 00:15:56,700 IT WANTS TO GO TO THE EDGE WHERE IT'S COOL, 253 00:15:56,733 --> 00:15:58,567 AND IT WANTS TO GET OUT. 254 00:15:58,600 --> 00:16:01,600 BUT IT'S GOT 400,000 MILES 255 00:16:01,633 --> 00:16:04,533 OF ALL THESE OPAQUE GASES BLOCKING ITS WAY. 256 00:16:04,567 --> 00:16:09,967 Narrator: THESE GASES AREN'T JUST DENSE -- THEY'RE HOT, 257 00:16:10,067 --> 00:16:15,400 SUPERHEATED TO OVER 12 1/2 MILLION DEGREES FAHRENHEIT. 258 00:16:15,433 --> 00:16:17,367 THE GAS IN THE RADIATION ZONE 259 00:16:17,400 --> 00:16:21,500 IS TRANSFORMED INTO WHAT SCIENTISTS CALL PLASMA. 260 00:16:24,433 --> 00:16:27,633 PLASMA IS THE FOURTH STATE OF MATTER. 261 00:16:27,667 --> 00:16:33,067 ATOMS IN NORMAL MATTER HAVE A NUCLEUS WITH ORBITING ELECTRONS. 262 00:16:33,100 --> 00:16:36,433 IN PLASMA, THE ATOMS HAVE BEEN TORN APART 263 00:16:36,467 --> 00:16:40,300 AND THE ELECTRONS RIPPED AWAY. 264 00:16:40,333 --> 00:16:44,333 HERE ON EARTH, WE'RE FAMILIAR WITH THE THREE MAIN STATES 265 00:16:44,367 --> 00:16:46,433 OF MATTER THAT WE'RE TAUGHT IN SCHOOL -- 266 00:16:46,467 --> 00:16:49,100 SOLIDS, LIQUIDS, AND GASES. 267 00:16:49,133 --> 00:16:52,267 YOU KNOW, WE HAVE THE ATMOSPHERE AS A GAS, THE OCEANS ARE WATER, 268 00:16:52,300 --> 00:16:54,800 THE GROUND THAT I STAND ON IS SOLID. 269 00:16:54,833 --> 00:16:56,700 BUT IN FACT, MOST OF THE UNIVERSE, 270 00:16:56,733 --> 00:17:00,600 INCLUDING STARS, CONSISTS OF PLASMA. 271 00:17:03,167 --> 00:17:05,067 Narrator: COMPARED TO THE REST OF THE UNIVERSE, 272 00:17:05,067 --> 00:17:08,400 EARTH IS A CALM PLACE. 273 00:17:08,433 --> 00:17:09,733 MOST OF THE TIME, 274 00:17:09,767 --> 00:17:13,067 IT'S NOT HOT OR VIOLENT ENOUGH HERE TO CREATE PLASMA. 275 00:17:16,867 --> 00:17:21,633 THE BEST PLACE TO WITNESS THE POWER OF PLASMA ON EARTH 276 00:17:21,667 --> 00:17:23,333 IS INSIDE A LIGHTNING STRIKE. 277 00:17:26,367 --> 00:17:32,600 TEMPERATURES INSIDE A BOLT CAN REACH 53,000 DEGREES FAHRENHEIT, 278 00:17:32,633 --> 00:17:35,667 ENOUGH TO MOMENTARILY RIP A FEW ATOMS APART. 279 00:17:37,700 --> 00:17:40,200 THE PLASMA LASTS AN INSTANT. 280 00:17:40,233 --> 00:17:44,067 THEN THE ELECTRONS REBIND AND IT'S GONE. 281 00:17:47,733 --> 00:17:50,200 BUT IN OUR MASSIVE SUN, 282 00:17:50,233 --> 00:17:53,133 THE PLASMA LASTS FOR BILLIONS OF YEARS 283 00:17:53,167 --> 00:17:54,333 AND MAKES UP 284 00:17:54,367 --> 00:17:57,933 THE ENTIRE 200,000-MILE-DEEP RADIATION ZONE. 285 00:18:00,500 --> 00:18:02,600 WORSE FOR OUR PHOTON, 286 00:18:02,633 --> 00:18:08,167 THE PLASMA IS ELECTRICALLY CHARGED, FORMING A COSMIC TRAP. 287 00:18:13,167 --> 00:18:15,633 AND A PLASMA IS OPAQUE TO RADIATION 288 00:18:15,667 --> 00:18:18,600 BECAUSE LIGHT INTERACTS MUCH MORE STRONGLY 289 00:18:18,633 --> 00:18:20,300 WITH ELECTRONICALLY CHARGED OBJECTS 290 00:18:20,333 --> 00:18:22,067 THAN WITH NEUTRAL OBJECTS. 291 00:18:22,067 --> 00:18:23,533 SO, WHEN YOU HAVE A NEUTRAL ATOM, 292 00:18:23,567 --> 00:18:25,433 LIGHT IN GENERAL CAN PASS BY. 293 00:18:25,467 --> 00:18:27,067 BUT WHEN YOU SEPARATED THE CHARGES 294 00:18:27,067 --> 00:18:28,500 AND YOU HAVE POSITIVE AND NEGATIVE CHARGES 295 00:18:28,533 --> 00:18:32,600 LOCATED EVERYWHERE, THE LIGHT CAN'T MAKE IT THROUGH. 296 00:18:32,633 --> 00:18:35,433 Narrator: OUR PHOTON, IN THE FORM OF A GAMMA RAY, 297 00:18:35,467 --> 00:18:37,400 HAS ENTERED THE RADIATION ZONE 298 00:18:37,433 --> 00:18:41,100 AND SMASHED INTO A CHARGED PLASMA PARTICLE. 299 00:18:41,133 --> 00:18:42,600 FOR A FRACTION OF A SECOND, 300 00:18:42,633 --> 00:18:47,567 THE PARTICLE ABSORBS THE PHOTON, THEN SPITS IT BACK OUT, 301 00:18:47,600 --> 00:18:51,333 AND THE PHOTON COLLIDES WITH ANOTHER PARTICLE. 302 00:18:54,467 --> 00:18:56,733 Plait: EVERY TIME IT GOES A LITTLE BIT OF A DISTANCE, 303 00:18:56,767 --> 00:18:58,467 IT BASICALLY SLAMS INTO AN ATOM, 304 00:18:58,500 --> 00:19:01,833 IS ABSORBED AND READMITTED IN SOME RANDOM DIRECTION. 305 00:19:01,867 --> 00:19:03,667 SO, INSTEAD OF JUST FLYING OUT, 306 00:19:03,700 --> 00:19:06,733 IT'S BOUNCING AROUND COUNTLESS, COUNTLESS, COUNTLESS TIMES 307 00:19:06,767 --> 00:19:08,567 UNTIL FINALLY, IT REACHES THE EDGE OF THE STAR. 308 00:19:10,067 --> 00:19:13,333 Narrator: IT'S AN ATOMIC GAME OF BASKETBALL 309 00:19:13,367 --> 00:19:17,267 WITH A COURT REPRESENTING THE RADIATION ZONE. 310 00:19:17,300 --> 00:19:21,233 THE PLAYERS STAND IN FOR THE PARTICLES AND THE PLASMA 311 00:19:21,267 --> 00:19:23,067 AND THE BALL IS THE PHOTON. 312 00:19:25,500 --> 00:19:27,067 Filippenko: SO, THE BASKETBALL 313 00:19:27,067 --> 00:19:30,933 IS BEING THROWN FROM ONE PLAYER TO ANOTHER SEEMINGLY RANDOMLY. 314 00:19:30,967 --> 00:19:34,267 IT'S NOT MAKING A LOT OF PROGRESS DOWN THE COURT, 315 00:19:34,300 --> 00:19:37,267 BUT IT IS GRADUALLY MAKING PROGRESS. 316 00:19:37,300 --> 00:19:39,533 GRADUALLY OVER TIME, IT IS GOING 317 00:19:39,567 --> 00:19:42,633 FROM THE HOTTER PARTS OF THE CORE OUTWARD 318 00:19:42,667 --> 00:19:44,600 TOWARD COOLER TEMPERATURES. 319 00:19:44,633 --> 00:19:46,367 THAT'S WHERE IT WANTS TO GET. 320 00:19:46,400 --> 00:19:48,300 IT'S A RANDOM-LOOKING PROCESS, 321 00:19:48,333 --> 00:19:52,833 BUT IT'S DIRECTED IN A CERTAIN DIRECTION WITH TIME. 322 00:19:57,200 --> 00:19:59,767 Narrator: THE PHOTON WANTS TO GO STRAIGHT UP THE COURT -- 323 00:19:59,800 --> 00:20:02,733 ITS QUICKEST ROUTE -- 324 00:20:02,767 --> 00:20:05,333 BUT IS BOUNCED AND THROWN AROUND THE RADIATION ZONE, 325 00:20:05,367 --> 00:20:07,567 SLOWING TO A CRAWL. 326 00:20:10,200 --> 00:20:15,167 THIS BRUISING PROCESS TRANSFORMS THE PHOTON. 327 00:20:15,200 --> 00:20:17,233 WHEN A PHOTON, A LITTLE PACKET OF LIGHT, 328 00:20:17,267 --> 00:20:18,967 IS CREATED IN THE CENTER OF THE STAR, 329 00:20:19,000 --> 00:20:22,233 IT'S ACTUALLY A GAMMA RAY, SUPER HIGH ENERGY BIT OF LIGHT. 330 00:20:22,267 --> 00:20:25,200 AND IT CAN'T GO VERY FAR BECAUSE AS SOON AS IT DOES, 331 00:20:25,233 --> 00:20:27,667 BOOM, IT HITS ANOTHER ATOM AND GETS ABSORBED. 332 00:20:29,967 --> 00:20:31,100 EVERY TIME IT DOES THIS, 333 00:20:31,133 --> 00:20:33,933 IT LOSES A LITTLE BIT OF THAT ENERGY. 334 00:20:35,933 --> 00:20:37,767 Narrator: OVER SEVERAL HUNDRED THOUSAND YEARS, 335 00:20:37,800 --> 00:20:42,100 SOMETIMES EVEN A MILLION, THE PHOTON KEEPS BOUNCING 336 00:20:42,133 --> 00:20:46,433 THROUGH THE DENSE RADIATION ZONE. 337 00:20:46,467 --> 00:20:51,367 EACH COLLISION SAPS A TINY BIT OF ENERGY, 338 00:20:51,400 --> 00:20:54,867 TRANSFORMING IT FROM A LETHAL GAMMA-RAY PHOTON 339 00:20:54,900 --> 00:20:56,933 TO A LOWER ENERGY X-RAY. 340 00:21:00,800 --> 00:21:04,267 NEARLY A MILLION YEARS AFTER ITS CREATION IN THE CORE, 341 00:21:04,300 --> 00:21:08,767 THE PHOTON HAS MADE IT THROUGH THE RADIATION ZONE, 342 00:21:08,800 --> 00:21:11,667 BUT ITS QUEST TO ESCAPE IS NOT OVER YET. 343 00:21:13,633 --> 00:21:15,800 IT'S ABOUT TO HITCH A WILD RIDE 344 00:21:15,833 --> 00:21:19,167 ON THE SUN'S FEROCIOUS INTERNAL ROLLER COASTER... 345 00:21:20,900 --> 00:21:24,600 ...A PLACE SO VIOLENT, IT MAKES THE SUN ROAR. 346 00:21:45,233 --> 00:21:48,667 Narrator: A PHOTON, NATURE'S ENERGY-DELIVERY SYSTEM, 347 00:21:48,700 --> 00:21:51,100 HAS SPENT UP TO A MILLION YEARS 348 00:21:51,133 --> 00:21:53,100 IN THE MAZE OF THE SUN'S INTERIOR 349 00:21:53,133 --> 00:21:55,167 ON ITS JOURNEY TOWARD THE EARTH. 350 00:21:57,400 --> 00:22:01,567 THE PHOTON HAS FOUGHT ITS WAY THROUGH 3/4 OF THE SUN'S RADIUS. 351 00:22:04,100 --> 00:22:06,300 BATTERED AND SAPPED OF ENERGY, 352 00:22:06,333 --> 00:22:09,733 IT IS MORPHED FROM A DEADLY GAMMA RAY TO AN X-RAY. 353 00:22:13,233 --> 00:22:17,667 BUT NOW IT ENTERS THE MYSTERIOUS BOILING LAYER OF THE SUN, 354 00:22:17,700 --> 00:22:19,400 THE CONVECTION ZONE. 355 00:22:23,567 --> 00:22:26,967 THE CONVECTION ZONE LIES BETWEEN THE RADIATION ZONE 356 00:22:27,067 --> 00:22:32,567 AND THE SUN'S SURFACE AND IS 125,000 MILES DEEP. 357 00:22:34,800 --> 00:22:38,667 WE CAN'T SEE THE CONVECTION ZONE DIRECTLY. 358 00:22:38,700 --> 00:22:43,667 THIS REGION OF THE SUN IS STILL OPAQUE TO OUR TELESCOPES, 359 00:22:43,700 --> 00:22:45,733 BUT WE CAN HEAR IT. 360 00:22:49,833 --> 00:22:55,067 NASA'S SOLAR DYNAMICS OBSERVATORY LISTENS TO THE SUN. 361 00:22:55,100 --> 00:22:59,067 THE SOUND IT PICKS UP IS TOO DEEP FOR HUMANS TO HEAR, 362 00:22:59,067 --> 00:23:02,667 BUT IF YOU SPEED UP 40 DAYS' RECORDING 363 00:23:02,700 --> 00:23:06,833 INTO A FEW SECONDS, THIS IS WHAT YOU GET. 364 00:23:06,867 --> 00:23:11,833 [ RUMBLING ] 365 00:23:11,867 --> 00:23:15,233 IT'S THE SOUND OF CHAOS. 366 00:23:18,200 --> 00:23:20,600 SINCE WE CAN'T SEE INTO THE SUN, 367 00:23:20,633 --> 00:23:23,400 ITS SOUND IS VITAL TO SCIENTISTS. 368 00:23:26,633 --> 00:23:31,800 WHEN A GUN FIRES, THE BULLET RUSHES OUT AND SMASHES INTO AIR, 369 00:23:31,833 --> 00:23:34,400 CREATING WAVES OF TURBULENCE. 370 00:23:37,533 --> 00:23:39,500 WHEN WE HEAR THE GUN FIRING, 371 00:23:39,533 --> 00:23:42,867 THESE WAVES VIBRATE OUR EARDRUMS. 372 00:23:46,067 --> 00:23:48,567 WHAT WE SEE HERE IS SOUND. 373 00:23:48,600 --> 00:23:53,333 THE SUN WORKS THE SAME WAY ON A MUCH LARGER SCALE. 374 00:23:56,933 --> 00:23:59,900 WHEN WE SEE THESE WAVES MOVING ACROSS, 375 00:24:00,067 --> 00:24:02,967 WHAT WE'RE LOOKING AT IS WHEN MATERIAL MOVES UP 376 00:24:03,067 --> 00:24:05,567 FROM INSIDE THE SUN AND IT MAKES NOISE. 377 00:24:05,600 --> 00:24:07,067 IT JUST, LIKE, RAN INTO A SURFACE. 378 00:24:07,067 --> 00:24:10,267 IT JUST RAN INTO A WALL, AND IT GENERATES SOUND. 379 00:24:10,300 --> 00:24:13,833 AND WE SEE THAT SOUND MOVING ALL AROUND THE SUN. 380 00:24:13,867 --> 00:24:16,667 Narrator: SOUND WAVES CRASHING THROUGH THE PLASMA 381 00:24:16,700 --> 00:24:20,133 CREATE RIPPLES IN THE SUN'S SURFACE. 382 00:24:20,167 --> 00:24:22,433 AND ALL WE SEE ARE THESE RIPPLES. 383 00:24:22,467 --> 00:24:25,333 THOSE ARE THE ACTUAL SOUND WAVES OF THE SUN, 384 00:24:25,367 --> 00:24:27,367 AND THEY MOVE AROUND THE ENTIRE SUN. 385 00:24:27,400 --> 00:24:28,967 THEY MOVE DOWN INSIDE THE SUN. 386 00:24:29,067 --> 00:24:30,933 THEY MOVE BACK UP TO THE SURFACE. 387 00:24:31,967 --> 00:24:34,367 Narrator: BY TRACKING THE SOUND, 388 00:24:34,400 --> 00:24:36,900 SCIENTISTS CAN SEE THE INVISIBLE. 389 00:24:39,367 --> 00:24:40,933 THEY PICK UP SOUND WAVES 390 00:24:40,967 --> 00:24:43,433 SMASHING AGAINST THE SUN'S SURFACE 391 00:24:43,467 --> 00:24:46,400 AND RESONATING THROUGHOUT THE SOLAR INTERIOR... 392 00:24:48,300 --> 00:24:52,067 ...REVEALING A VIOLENT, BOILING CONVECTION ZONE. 393 00:24:56,200 --> 00:24:59,900 Oluseyi: THE SUN CAN BE SAID TO BE RINGING. 394 00:25:00,067 --> 00:25:02,300 YOU HAVE THIS HOT GAS RISING. 395 00:25:02,333 --> 00:25:04,200 YOU HAVE COOL GAS FALLING. 396 00:25:04,233 --> 00:25:06,067 YOU HAVE ALL THIS TURBULENCE. 397 00:25:06,067 --> 00:25:09,533 YOU HAVE SO MUCH ACTION GOING ON THAT IT CAUSES THE SUN TO RING. 398 00:25:09,567 --> 00:25:13,667 Narrator: COLUMNS OF GASES RISE AND FALL, 399 00:25:13,700 --> 00:25:18,767 CHURNED BY HEAT FROM BELOW. 400 00:25:18,800 --> 00:25:20,433 Gilbert: IF YOU LOOK AT WATER BOILING, 401 00:25:20,467 --> 00:25:24,367 BUBBLES OF GAS OR WATER ARE RISING UP BECAUSE THEY'RE HOT. 402 00:25:24,400 --> 00:25:26,533 AND THEN THEY COOL OFF, AND THEN THEY SINK BACK DOWN. 403 00:25:26,567 --> 00:25:29,067 AND IF YOU LOOK AT A POT OF BOILING WATER, 404 00:25:29,067 --> 00:25:32,067 THAT'S THE SAME PHENOMENA THAT'S GOING ON THE SUN, 405 00:25:32,067 --> 00:25:36,067 BUT WITH HOT PLASMA INSTEAD OF WATER. 406 00:25:36,100 --> 00:25:38,433 Narrator: AT THE BOTTOM OF THE CONVECTION ZONE, 407 00:25:38,467 --> 00:25:41,800 PHOTONS SMASH INTO ATOMS IN THE PLASMA, 408 00:25:41,833 --> 00:25:43,400 HEATING THEM TO A BOIL. 409 00:25:45,433 --> 00:25:48,833 BUT THIS TIME, THE PHOTONS ARE ABSORBED BY THE ATOMS. 410 00:25:50,700 --> 00:25:53,800 THE HOT ATOMS RIDE THE BOILING CURRENT TO THE TOP, 411 00:25:53,833 --> 00:25:56,333 DRAGGING THE PHOTONS WITH THEM. 412 00:25:59,433 --> 00:26:02,467 SO, IT'S ALMOST LIKE THIS CONVEYOR BELT OF MATERIAL. 413 00:26:02,500 --> 00:26:05,400 PHOTONS ARE ACTUALLY HITCHHIKING A RIDE ON THE ATOMS 414 00:26:05,433 --> 00:26:08,833 THAT ARE TRAVELING UPWARD THROUGH THIS HEAT TRANSFER. 415 00:26:08,867 --> 00:26:11,167 SO, IT'S A MUCH EASIER RIDE IN THE CONVECTION LAYER 416 00:26:11,200 --> 00:26:12,900 THAN IT IS IN THE RADIATION ZONE. 417 00:26:17,733 --> 00:26:20,600 Narrator: IT'S AS IF OUR PHOTON WERE NOW IN THE HANDS 418 00:26:20,633 --> 00:26:23,667 OF A SINGLE PLAYER MAKING A FAST BREAK. 419 00:26:25,967 --> 00:26:30,067 Gilbert: IN THE CONVECTION LAYER, IT'S A DIRECT PATH. 420 00:26:30,067 --> 00:26:33,500 ONE PLAYER CAN ACTUALLY HOLD ON TO THIS BASKETBALL OR PHOTON 421 00:26:33,533 --> 00:26:35,900 FOR A LOT LONGER IN A DIRECT PATH. 422 00:26:38,167 --> 00:26:39,400 Narrator: BY NOT PASSING, 423 00:26:39,433 --> 00:26:42,400 THE ATOM TAKES THE BALL QUICKLY UP THE COURT. 424 00:26:45,433 --> 00:26:48,067 THE PHOTON'S JOURNEY THROUGH THE CONVECTION ZONE 425 00:26:48,067 --> 00:26:50,967 TAKES JUST ONE WEEK. 426 00:26:51,067 --> 00:26:54,833 BUT IN THAT TIME, THE PHOTON IS TRANSFORMED. 427 00:26:54,867 --> 00:26:57,433 THE BOTTOM OF THE CONVECTION ZONE 428 00:26:57,467 --> 00:27:01,400 IS AROUND 360,000 DEGREES FAHRENHEIT. 429 00:27:03,633 --> 00:27:05,900 THE TOP -- JUST 10,000. 430 00:27:09,267 --> 00:27:14,167 SO, AS THE PHOTON RISES UP, IT COOLS, LOSING ENERGY, 431 00:27:14,200 --> 00:27:17,900 CHANGING FROM AN ENERGETIC X-RAY TO VISIBLE LIGHT. 432 00:27:22,267 --> 00:27:24,800 SO, IT STARTS AS A HIGH-ENERGY X-RAY 433 00:27:24,833 --> 00:27:27,433 AT THE BOTTOM OF THE CONVECTION ZONE, MOVES ITS WAY UP, 434 00:27:27,467 --> 00:27:29,467 IT LOSES A LITTLE BIT OF THAT ENERGY. 435 00:27:29,500 --> 00:27:30,867 BY THE TIME IT LEAVES THERE, 436 00:27:30,900 --> 00:27:33,167 IT'S CLOSER TO THE KIND OF LIGHT THAT WE SEE, 437 00:27:33,200 --> 00:27:34,467 WHICH IS VISIBLE LIGHT. 438 00:27:38,133 --> 00:27:40,167 Narrator: AT THE TOP OF THE CONVECTION ZONE, 439 00:27:40,200 --> 00:27:42,467 THE ATOM RELEASES THE PHOTON, 440 00:27:42,500 --> 00:27:45,467 WHICH SHOOTS OUT AS VISIBLE LIGHT. 441 00:27:47,133 --> 00:27:48,633 THIS COOLS THE ATOMS, 442 00:27:48,667 --> 00:27:51,867 WHICH FALL BACK DOWN TO ABSORB MORE PHOTONS, 443 00:27:51,900 --> 00:27:53,833 HEAT UP, AND RISE AGAIN. 444 00:27:56,433 --> 00:27:59,833 THE PHOTON IS NOW JUST BELOW THE SUN'S SURFACE. 445 00:28:02,467 --> 00:28:07,867 BUT THE CHURNING CONVECTION ZONE UNLEASHES ANOTHER FORCE -- 446 00:28:07,900 --> 00:28:10,767 A FORCE THAT POWERS HUGE STORMS, 447 00:28:10,800 --> 00:28:15,067 DETONATES BOMBS, AND THREATENS TO STOP LIGHT'S ESCAPE. 448 00:28:32,533 --> 00:28:35,267 Narrator: IN THE SUN'S CORE, 449 00:28:35,300 --> 00:28:40,067 NUCLEAR FUSION HAS CREATED A PHOTON, A PACKET OF LIGHT. 450 00:28:40,067 --> 00:28:44,067 IT HAS BATTLED THROUGH THE RADIATION ZONE, 451 00:28:44,067 --> 00:28:46,800 BEEN DRAGGED UP THROUGH THE CONVECTION ZONE 452 00:28:46,833 --> 00:28:51,833 ON COLUMNS OF HOT PLASMA, HURDLING TOWARDS ITS ESCAPE. 453 00:28:54,767 --> 00:28:56,933 ON THIS MILLION-YEAR JOURNEY, 454 00:28:56,967 --> 00:29:01,700 THE PHOTON HAS CHANGED FROM AN INVISIBLE DEADLY GAMMA RAY 455 00:29:01,733 --> 00:29:05,100 TO THE KIND OF LIFE-GIVING LIGHT WE SEE HERE ON EARTH. 456 00:29:11,067 --> 00:29:15,333 FINALLY, IT HAS REACHED THE SURFACE -- 457 00:29:15,367 --> 00:29:19,067 THE VISIBLE SHELL OF THE SUN, THE PHOTOSPHERE. 458 00:29:21,867 --> 00:29:23,067 Gilbert: THE PHOTOSPHERE, 459 00:29:23,100 --> 00:29:24,667 WHICH IS BASICALLY THE VISIBLE PART OF THE SUN, 460 00:29:24,700 --> 00:29:28,233 OR THE SURFACE, IS WHAT WE SEE WHEN WE LOOK UP AT THE SUN. 461 00:29:28,267 --> 00:29:31,333 WE'RE SEEING VISIBLE LIGHT COMING FROM THAT VERY LAYER, 462 00:29:31,367 --> 00:29:32,433 THE PHOTOSPHERE. 463 00:29:35,567 --> 00:29:39,067 Narrator: THE BALL OF BLINDING LIGHT WE PERCEIVE 464 00:29:39,067 --> 00:29:43,567 HIDES A SPECTACULAR AND SAVAGE WORLD. 465 00:29:46,767 --> 00:29:50,333 THE SUN FROM A DISTANCE LOOKS QUIET AND SERENE, 466 00:29:50,367 --> 00:29:53,433 BUT IF YOU TAKE A CLOSE-UP OF THE SURFACE OF THE SUN, 467 00:29:53,467 --> 00:29:56,400 YOU SEE THAT IT'S CHURNING WITH ACTIVITY. 468 00:29:58,200 --> 00:30:01,667 Krauss: IT'S BEAUTIFUL AND TERRIFYING AT THE SAME TIME -- 469 00:30:01,700 --> 00:30:04,833 HUGE STORMS OF MATERIAL BUBBLING AND BOILING. 470 00:30:04,867 --> 00:30:06,333 IT LOOKS LIKE A WITCH'S BREW, 471 00:30:06,367 --> 00:30:08,367 EXCEPT THE BUBBLES IN THE WITCH'S BREW 472 00:30:08,400 --> 00:30:10,433 ARE LARGER THAN THE SIZE OF THE EARTH. 473 00:30:12,367 --> 00:30:15,733 Narrator: THE SURFACE OF THE SUN IS A TURBULENT BARRIER. 474 00:30:17,600 --> 00:30:21,567 AND ONCE AGAIN, OUR PHOTON GETS TAKEN HOSTAGE. 475 00:30:32,500 --> 00:30:36,067 AT KITT PEAK OBSERVATORY IN ARIZONA, 476 00:30:36,100 --> 00:30:40,567 SOLAR ASTRONOMER MATT PENN STUDIES THIS SOLAR SURFACE 477 00:30:40,600 --> 00:30:44,600 TO DISCOVER HOW PHOTONS OF LIGHT GET TRAPPED. 478 00:30:44,633 --> 00:30:46,367 THERE'S A BUNCH OF CIRRUS TODAY, 479 00:30:46,400 --> 00:30:48,200 BUT HOPEFULLY, WE'LL GET SOME DATA. 480 00:30:52,133 --> 00:30:54,100 Narrator: USING THE McMATH-PIERCE TELESCOPE, 481 00:30:54,133 --> 00:31:00,633 HE FOCUSES THE SUN'S LIGHT TO SCAN THE PHOTOSPHERE IN DETAIL. 482 00:31:00,667 --> 00:31:03,167 Penn: SO, WHAT WE'VE GOT ARE A FEW SMALL SUN SPOTS 483 00:31:03,200 --> 00:31:04,500 ON A DISC OF THE SUN. 484 00:31:04,533 --> 00:31:07,933 WE'VE GOT TWO SUN SPOTS, TWO LARGE ONES. 485 00:31:07,967 --> 00:31:09,500 THEY'RE HEADING OFF TO THE EDGE OF THE SUN, 486 00:31:09,533 --> 00:31:10,967 TO THE LIMB OF THE SUN. 487 00:31:11,067 --> 00:31:13,400 BUT THEY'RE ALL ACCOMPANIED BY A SMALLER SUN SPOTS, 488 00:31:13,433 --> 00:31:15,067 GROUPS OF SMALLER ONES, FOLLOWING THEM. 489 00:31:17,867 --> 00:31:21,400 Narrator: SUN SPOTS MARK AREAS WHERE LIGHT IS TRAPPED. 490 00:31:23,567 --> 00:31:25,667 Penn: SO, A SUN SPOT FORMS A DARK SPOT 491 00:31:25,700 --> 00:31:28,100 BY REMOVING ENERGY FROM THAT PART OF THE SUN. 492 00:31:28,133 --> 00:31:30,733 IT'S BLOCKING THE CONVECTIVE FLOWS THAT TRANSPORT THE HEAT 493 00:31:30,767 --> 00:31:33,200 AND THE LIGHT FROM INSIDE THE SUN TO SPACE. 494 00:31:33,233 --> 00:31:35,067 SO, WHAT WE SEE THEN IS A COOLER REGION 495 00:31:35,067 --> 00:31:36,467 THAT APPEARS DARK TO US. 496 00:31:39,067 --> 00:31:43,433 Narrator: A POWERFUL FORCE STOPS OUR PHOTON DEAD IN ITS TRACKS, 497 00:31:43,467 --> 00:31:47,333 PREVENTING ITS LIGHT AND ENERGY FROM LEAVING THE SUN'S SURFACE. 498 00:31:50,767 --> 00:31:53,167 THAT FORCE IS MAGNETISM. 499 00:31:57,400 --> 00:32:00,667 SUN SPOTS TAKE SHAPE WHERE INTENSE MAGNETISM 500 00:32:00,700 --> 00:32:05,400 FROM DEEP INSIDE THE SUN BLASTS UP THROUGH THE PHOTOSPHERE. 501 00:32:09,367 --> 00:32:12,500 THE MAGNETIC FIELDS ARE SO STRONG THAT IT ACTUALLY 502 00:32:12,533 --> 00:32:17,267 STOPS THE CONVECTIVE MOTION OF HOT INNER MATERIAL 503 00:32:17,300 --> 00:32:18,533 FROM FLOWING TO THE SURFACE. 504 00:32:18,567 --> 00:32:20,867 SO, YOU ACTUALLY GET WHAT LOOKS LIKE A COOL SPOT 505 00:32:20,900 --> 00:32:23,467 ON THE SURFACE OF THE SUN. 506 00:32:23,500 --> 00:32:25,333 Narrator: THEY CAN BE HUGE, 507 00:32:25,367 --> 00:32:28,400 THE LARGEST OVER 10 TIMES THE SIZE OF EARTH. 508 00:32:35,200 --> 00:32:37,833 THE MAGNETISM THAT GENERATES THESE SUN SPOTS 509 00:32:37,867 --> 00:32:41,100 FORMS FIELD LINES COVERING THE SUN. 510 00:32:41,133 --> 00:32:44,067 ON OUR SOLID EARTH, THE WHOLE PLANET 511 00:32:44,067 --> 00:32:49,767 ROTATES TOGETHER, INCLUDING ITS MAGNETIC FIELD. 512 00:32:49,800 --> 00:32:53,167 BUT THE SUN IS A BIG BALL OF GAS, 513 00:32:53,200 --> 00:32:56,067 AND THE SAME RULES DON'T APPLY. 514 00:32:56,100 --> 00:32:58,400 YOU SEE, THERE'S NOTHING SOLID ABOUT THE SUN. 515 00:32:58,433 --> 00:32:59,600 IT'S A BIG BALL OF GAS. 516 00:32:59,633 --> 00:33:01,500 IT TURNS ON ITS AXIS, 517 00:33:01,533 --> 00:33:04,167 BUT THE EQUATOR ROTATES FASTER THAN THE POLES. 518 00:33:04,200 --> 00:33:05,567 THE SUN TWISTS ITSELF UP, 519 00:33:05,600 --> 00:33:07,867 AND THE MAGNETIC FIELD TWISTS WITH IT. 520 00:33:10,233 --> 00:33:14,267 Narrator: IT ROTATES FASTER AT THE EQUATOR THAN AT THE POLES, 521 00:33:14,300 --> 00:33:17,567 TWISTING AND TANGLING ITS MAGNETIC FIELD 522 00:33:17,600 --> 00:33:19,233 WITH EACH ROTATION. 523 00:33:20,533 --> 00:33:24,400 THE RESULT -- MAGNETIC MAYHEM. 524 00:33:28,200 --> 00:33:31,100 SO, WHEN THESE FIELDS EMERGE FROM THE SURFACE OF THE SUN, 525 00:33:31,133 --> 00:33:34,100 THEY HAVE ALL THIS STORED ENERGY IN THEM. 526 00:33:34,133 --> 00:33:36,067 THEY'RE, LIKE, ALL TWISTED AND KNOTTED, 527 00:33:36,100 --> 00:33:38,133 LIKE RUBBER BANDS YOU JUST TWIST AND KNOT 528 00:33:38,167 --> 00:33:39,467 WITH ALL THIS ENERGY IN IT. 529 00:33:39,500 --> 00:33:41,067 IF YOU EVER TWIST AND TWIST AND TWIST A RUBBER BAND 530 00:33:41,100 --> 00:33:42,233 AND PULL IT STRAIGHT, 531 00:33:42,267 --> 00:33:44,667 YOU CAN TELL, YOU CAN FEEL THAT TENSION IN IT. 532 00:33:46,933 --> 00:33:49,400 Narrator: WHERE THE MAGNETIC LINES TWIST, 533 00:33:49,433 --> 00:33:52,467 FLOWS OF PLASMA CONTAINING OUR PHOTON 534 00:33:52,500 --> 00:33:54,067 CAN'T REACH THE SURFACE. 535 00:33:55,800 --> 00:33:58,100 SO, WHAT HAPPENS IS YOU HAVE THESE PACKETS OF GAS 536 00:33:58,133 --> 00:34:00,867 WHICH REACH THE SURFACE, COOL OFF, 537 00:34:00,900 --> 00:34:03,267 BUT ARE TRAPPED RIGHT THERE BY THE MAGNETISM. 538 00:34:06,200 --> 00:34:08,200 Narrator: A PATCH OF THE SUN GOES DARK 539 00:34:08,233 --> 00:34:10,967 WHERE LIGHT CAN'T ESCAPE. 540 00:34:11,067 --> 00:34:13,067 A SUN SPOT IS BORN. 541 00:34:14,600 --> 00:34:17,133 BUT IN THAT TANGLE OF MAGNETIC LINES, 542 00:34:17,167 --> 00:34:20,400 SOMETHING EVENTUALLY HAS TO SNAP. 543 00:34:20,433 --> 00:34:23,500 Oluseyi: THE MAGNETIC FIELDS ARE VERY UNHAPPY. 544 00:34:23,533 --> 00:34:25,167 THEY DON'T LIKE THE STATE THAT THEY'RE IN, 545 00:34:25,200 --> 00:34:27,400 AND ALL THEY WANT TO DO IS UNRAVEL. 546 00:34:31,867 --> 00:34:34,167 Narrator: HUGE LOOPS OF MAGNETIC ENERGY 547 00:34:34,200 --> 00:34:36,567 ARCH OUT OVER THE SUN SPOTS. 548 00:34:39,533 --> 00:34:43,933 TWISTED AND UNSTABLE, DESPERATE TO SPEW THEIR ENERGY, 549 00:34:43,967 --> 00:34:48,333 THEY CREATE A MAGNETIC BOMB PRIMED TO EXPLODE. 550 00:34:51,133 --> 00:34:53,067 Oluseyi: AND SO, IF ONE MAGNETIC FIELD WITH STORED ENERGY 551 00:34:53,100 --> 00:34:56,667 SEES ANOTHER MAGNETIC FIELD, THOSE TWO LOOK AT EACH OTHER 552 00:34:56,700 --> 00:35:00,067 AND SAY, "HEY, IF WE CONNECT, WE CAN GET RID OF A LOT OF ENERGY." 553 00:35:00,100 --> 00:35:01,433 THEY DO SO, THEY RECONNECT. 554 00:35:01,467 --> 00:35:02,900 BADDOW! 555 00:35:12,367 --> 00:35:15,400 Plait: IT'S A HUGE EXPLOSION, AND WE CALL IT A SOLAR FLARE. 556 00:35:17,800 --> 00:35:21,433 AND THIS CAN BE EQUIVALENT TO MILLIONS OF NUCLEAR WEAPONS 557 00:35:21,467 --> 00:35:24,200 EXPLODING SIMULTANEOUSLY. 558 00:35:26,700 --> 00:35:31,433 Narrator: SOLAR FLARES ERUPT OUTWARDS INTO SPACE 559 00:35:31,467 --> 00:35:34,067 AT UP TO 4 1/2 MILLION MILES AN HOUR... 560 00:35:36,133 --> 00:35:38,567 ...RELEASING MASSIVE AMOUNTS OF ENERGY. 561 00:35:42,900 --> 00:35:44,800 Oluseyi: MAGNETIC FIELDS ARE THROWING PLASMA 562 00:35:44,833 --> 00:35:46,933 FROM THE SURFACE OF THE SUN. 563 00:35:46,967 --> 00:35:49,500 SUDDENLY, THERE'S A LARGE OUTPOURING OF LIGHT. 564 00:35:53,200 --> 00:35:54,933 Narrator: AFTER NEARLY A MILLION YEARS, 565 00:35:54,967 --> 00:35:58,167 OUR PACKET OF LIGHT FINALLY MAKES ITS ESCAPE. 566 00:36:02,467 --> 00:36:03,733 IT'S FREE, 567 00:36:03,767 --> 00:36:08,500 CATAPULTING OUT ALONG WITH TRILLIONS OF OTHER PHOTONS, 568 00:36:08,533 --> 00:36:11,133 BUT THEIR JOURNEY IS FAR FROM OVER. 569 00:36:12,767 --> 00:36:17,633 MOST HURDLE ONWARDS TO THE FAR REACHES OF THE COSMOS, 570 00:36:17,667 --> 00:36:20,333 TO STRANGE, NEW WORLDS. 571 00:36:33,167 --> 00:36:37,133 Narrator: AFTER A NEARLY MILLION-YEAR JOURNEY 572 00:36:37,167 --> 00:36:41,733 THROUGH THE MOST HOSTILE ENVIRONMENT IN THE SOLAR SYSTEM, 573 00:36:41,767 --> 00:36:44,567 TINY PARCELS OF LIGHT -- 574 00:36:44,600 --> 00:36:48,433 PHOTONS -- FINALLY BURST FROM THE SUN'S SURFACE. 575 00:36:55,233 --> 00:36:56,767 Gilbert: THEY'RE FREE. 576 00:36:56,800 --> 00:37:00,767 THEY BASICALLY ARE FREE TO LEAVE THIS ARDUOUS JOURNEY 577 00:37:00,800 --> 00:37:02,300 THAT THEY'VE BEEN ON IN THE SUN. 578 00:37:02,333 --> 00:37:04,667 AND THEN THEY FLY OUT AT THE SPEED OF LIGHT. 579 00:37:06,833 --> 00:37:10,600 SO, IT'S KIND OF A "BREAKING OUT OF PRISON" TYPE OF FEELING 580 00:37:10,633 --> 00:37:12,433 FOR THOSE POOR PHOTONS. 581 00:37:14,633 --> 00:37:17,600 Narrator: THEY SPEED OUT INTO EMPTY SPACE 582 00:37:17,633 --> 00:37:20,667 AT 186,000 MILES PER SECOND. 583 00:37:22,600 --> 00:37:25,967 AND JUST 8.3 MINUTES AFTER IT LEAVES THE SUN, 584 00:37:26,067 --> 00:37:28,233 OUR PHOTON REACHES EARTH. 585 00:37:28,267 --> 00:37:30,500 Filippenko: THE NEXT TIME YOU LOOK AT A STAR IN THE SKY, 586 00:37:30,533 --> 00:37:33,067 YOU MIGHT CONSIDER THE AMAZING JOURNEY 587 00:37:33,100 --> 00:37:36,700 THE PHOTONS HAVE TAKEN ON THEIR WAY TO REACHING YOUR EYE. 588 00:37:39,933 --> 00:37:42,167 THEY WERE CREATED BY NUCLEAR REACTIONS 589 00:37:42,200 --> 00:37:46,100 DEEP IN THE CORE OF THE STARS, AND THEN THEY BOUNCED AROUND 590 00:37:46,133 --> 00:37:50,067 AND GOT DEGRADED INTO LOWER ENERGY PHOTONS. 591 00:37:50,100 --> 00:37:52,167 AND THEN IN THE CONVECTIVE ZONE, 592 00:37:52,200 --> 00:37:55,500 THEY WERE CARRIED BY MASS MOTIONS OF GAS. 593 00:37:55,533 --> 00:37:58,767 AND FINALLY, AT THE EDGE, THEY WERE SET FREE. 594 00:38:01,867 --> 00:38:06,833 AND THEY TRAVELED UNIMPEDED AND FINALLY REACHED YOUR EYES. 595 00:38:09,833 --> 00:38:13,167 Narrator: OUR PHOTON FINALLY ARRIVES, 596 00:38:13,200 --> 00:38:17,667 SMASHES INTO A LEAF, AND PASSES ON ITS ENERGY. 597 00:38:17,700 --> 00:38:19,800 THIS IS PHOTOSYNTHESIS, 598 00:38:19,833 --> 00:38:22,167 THE FUNDAMENTAL LINK IN OUR FOOD CHAIN. 599 00:38:26,067 --> 00:38:30,367 FINALLY, CARRYING ENERGY BORN INSIDE THE SUN'S CORE, 600 00:38:30,400 --> 00:38:33,333 OUR PHOTON AND BILLIONS LIKE IT 601 00:38:33,367 --> 00:38:37,833 IGNITE THE PRIMAL FIRES OF LIFE ON OUR PLANET. 602 00:38:37,867 --> 00:38:43,167 THE SUN'S LIGHT CREATES OUR FUEL, DRIVES OUR WEATHER, 603 00:38:43,200 --> 00:38:44,600 CHURNS OUR SEAS. 604 00:38:48,433 --> 00:38:51,767 EVERY SINGLE DAY, ENOUGH PHOTONS HIT THE EARTH 605 00:38:51,800 --> 00:38:54,767 TO POWER OUR CIVILIZATION FOR 27 YEARS. 606 00:38:56,867 --> 00:39:00,800 THE SUN'S LIGHT IS MORE THAN JUST WARMTH AND HEAT. 607 00:39:00,833 --> 00:39:04,500 IT PROVIDES EVERYTHING WE NEED TO SURVIVE. 608 00:39:04,533 --> 00:39:08,667 WITHOUT LIGHT, WE ARE NOTHING. 609 00:39:08,700 --> 00:39:11,733 Thaller: ALL OF THE ENERGY THAT POWERS OUR BIOLOGY, 610 00:39:11,767 --> 00:39:14,433 THE THING THAT MAKES OUR PLANET WARM, THAT MAKES LIFE POSSIBLE, 611 00:39:14,467 --> 00:39:16,067 THAT ALL COMES FROM THE SUN. 612 00:39:18,533 --> 00:39:22,433 Narrator: TRILLIONS OF PHOTONS HIT THE EARTH EVERY SECOND, 613 00:39:22,467 --> 00:39:24,667 EACH DELIVERING LIFE-GIVING ENERGY. 614 00:39:28,767 --> 00:39:32,833 BUT FOR THE UNIMAGINABLE NUMBER WHO PASS US BY, 615 00:39:32,867 --> 00:39:36,067 THE JOURNEY IS FAR FROM OVER. 616 00:39:36,067 --> 00:39:39,267 AROUND 80 MINUTES AFTER LEAVING THE SUN, 617 00:39:39,300 --> 00:39:41,700 THEY REACH SATURN. 618 00:39:41,733 --> 00:39:44,167 AFTER FOUR HOURS, NEPTUNE. 619 00:39:46,567 --> 00:39:48,867 ONCE A PHOTON LEAVES THE SURFACE OF THE SUN, 620 00:39:48,900 --> 00:39:51,267 IT'S FREE TO TRAVEL AS FAR AS IT CAN, 621 00:39:51,300 --> 00:39:54,800 AND AS FAR AS IT CAN CAN BE LITERALLY ACROSS THE UNIVERSE, 622 00:39:54,833 --> 00:39:57,100 BILLIONS OF LIGHT YEARS AWAY. 623 00:39:58,967 --> 00:40:00,767 Narrator: THEY SHOOT PAST THE OUTER REACHES 624 00:40:00,800 --> 00:40:04,833 OF OUR SOLAR SYSTEM IN JUST 18 HOURS. 625 00:40:04,867 --> 00:40:09,600 HERE, THE SUN IS A DIM SPECK IN THE DISTANCE. 626 00:40:09,633 --> 00:40:14,167 BUT THE PHOTONS KEEP ON GOING, OUT INTO DEEP SPACE. 627 00:40:18,133 --> 00:40:20,767 IN 1,200 YEARS, SOME OF THE PHOTONS 628 00:40:20,800 --> 00:40:25,267 REACH THE RED DWARF STAR SYSTEM KEPLER-62, 629 00:40:25,300 --> 00:40:29,733 A SOLAR SYSTEM WITH POTENTIALLY HABITABLE EARTH-LIKE PLANETS. 630 00:40:29,767 --> 00:40:32,533 IN OUR GALAXY, 631 00:40:32,567 --> 00:40:36,833 THERE ARE BILLIONS OF EARTH-LIKE PLANETS. 632 00:40:36,867 --> 00:40:42,200 IF THERE IS LIFE OUT THERE, CAN IT SEE THE LIGHT FROM OUR SUN? 633 00:40:42,233 --> 00:40:44,200 Filippenko: IF ALIENS EXIST OUT THERE, 634 00:40:44,233 --> 00:40:46,767 THEY COULD EASILY SEE THE LIGHT FROM OUR SUN. 635 00:40:46,800 --> 00:40:48,733 IF THEY'RE SUFFICIENTLY NEARBY, 636 00:40:48,767 --> 00:40:52,267 THE SUN MIGHT BE A NAKED-EYE STAR IN THEIR SKY 637 00:40:52,300 --> 00:40:53,633 OR WITH TELESCOPES, 638 00:40:53,667 --> 00:40:55,267 THEY WOULD BE ABLE TO DETECT THE SUN 639 00:40:55,300 --> 00:40:57,933 EVEN FROM VASTLY GREATER DISTANCES. 640 00:40:57,967 --> 00:41:00,067 SO, THERE'S A DISTINCT POSSIBILITY 641 00:41:00,067 --> 00:41:04,933 THAT ALIENS ARE STUDYING OUR SUN RIGHT NOW WITHOUT REALIZING 642 00:41:04,967 --> 00:41:08,067 THAT WE'RE HERE TRYING TO STUDY THE UNIVERSE, AS WELL. 643 00:41:10,633 --> 00:41:12,100 Narrator: HURDLING ON, 644 00:41:12,133 --> 00:41:17,433 THE PHOTONS PASS THE HORSEHEAD NEBULA IN 1,500 YEARS 645 00:41:17,467 --> 00:41:20,500 AND THE PILLARS OF CREATION IN 7,000. 646 00:41:22,600 --> 00:41:25,167 AT THESE DISTANCES, THE LIGHT FROM OUR STAR 647 00:41:25,200 --> 00:41:28,500 IS TOO SMALL TO BE SEEN WITH THE NAKED EYE, 648 00:41:28,533 --> 00:41:32,100 BUT IT WOULD BE VISIBLE WITH A POWERFUL TELESCOPE. 649 00:41:32,133 --> 00:41:33,833 Krauss: AND WITH THE BIGGEST TELESCOPES 650 00:41:33,867 --> 00:41:35,767 THAT WE CAN CREATE HERE ON EARTH OR IN SPACE, 651 00:41:35,800 --> 00:41:38,433 WE CAN ACTUALLY SEE THE LIGHT FROM STARS 652 00:41:38,467 --> 00:41:40,100 AT THE OTHER END OF THE UNIVERSE, 653 00:41:40,133 --> 00:41:42,067 OVER 10 BILLION LIGHT YEARS AWAY. 654 00:41:42,100 --> 00:41:45,933 AND SO THE LIGHT FROM OUR SUN IS TRAVELING ACROSS THE UNIVERSE. 655 00:41:48,267 --> 00:41:49,567 Plait: SO, THE LIGHT FROM OUR SUN, 656 00:41:49,600 --> 00:41:52,900 THE LIGHT FROM THE EARTH, TRAVELS ESSENTIALLY FOREVER. 657 00:41:52,933 --> 00:41:55,367 THE NEXT TIME YOU'RE OUT UNDER A CLEAR SKY 658 00:41:55,400 --> 00:41:56,633 AND YOU LOOK UP, 659 00:41:56,667 --> 00:41:58,867 YOU MIGHT WANT TO WAVE BECAUSE SOMEBODY OUT THERE 660 00:41:58,900 --> 00:42:01,300 MIGHT BE ABLE TO SEE YOU AND WAVE BACK. 661 00:42:03,600 --> 00:42:07,800 Narrator: OUR TINY STAR IS VISIBLE ACROSS THE UNIVERSE 662 00:42:07,833 --> 00:42:10,333 IF SOMEONE IS LOOKING. 663 00:42:10,367 --> 00:42:13,733 Krauss: THERE ISN'T A SINGLE PLACE IN OUR VISIBLE UNIVERSE 664 00:42:13,767 --> 00:42:15,767 THAT YOU WOULDN'T BE ABLE TO SEE THE SUN FROM, 665 00:42:15,800 --> 00:42:17,400 AND MAYBE THAT'S HEARTENING. 666 00:42:17,433 --> 00:42:19,467 MAYBE THERE'S SOME EVIDENCE OF OUR EXISTENCE 667 00:42:19,500 --> 00:42:20,633 AT THE OTHER END OF THE UNIVERSE. 668 00:42:20,667 --> 00:42:22,533 WON'T GET THERE FOR BILLIONS OF YEARS, 669 00:42:22,567 --> 00:42:25,233 BUT AT LEAST MAYBE WE WON'T BE FORGOTTEN. 670 00:42:25,267 --> 00:42:30,100 Narrator: A JOURNEY THAT STARTED DEEP INSIDE THE CORE OF THE SUN 671 00:42:30,133 --> 00:42:33,267 WITH A PHOTON, A MILLION-YEAR STRUGGLE 672 00:42:33,300 --> 00:42:35,667 TO FINALLY ESCAPE THE SUN'S GRIP. 673 00:42:38,400 --> 00:42:40,600 ONCE FREE, OUR PHOTON 674 00:42:40,633 --> 00:42:45,267 BROUGHT ENERGY, HEAT, AND LIFE TO OUR WORLD. 675 00:42:47,533 --> 00:42:53,300 LIGHT FROM OUR SUN JOINS LIGHT FROM TRILLIONS OF OTHER STARS 676 00:42:53,333 --> 00:42:55,767 JOURNEYING THROUGH THE UNIVERSE, 677 00:42:55,800 --> 00:42:59,067 SPREADING ENERGY THROUGHOUT THE COSMOS.