1 00:00:02,268 --> 00:00:04,303 NARRATOR: There's a violent star at the center 2 00:00:04,404 --> 00:00:05,404 of our solar system. 3 00:00:07,774 --> 00:00:12,644 The immense power, the roiling, boiling surface, 4 00:00:12,746 --> 00:00:13,746 the massive plumes. 5 00:00:13,847 --> 00:00:15,347 It's ridiculous. 6 00:00:15,448 --> 00:00:18,517 NARRATOR: And our planet is at its mercy. 7 00:00:18,618 --> 00:00:23,455 There are explosions and big giant eruptions of plasma 8 00:00:23,556 --> 00:00:24,857 that head straight to Earth. 9 00:00:26,526 --> 00:00:30,929 We have to understand these better to protect ourselves. 10 00:00:31,031 --> 00:00:35,467 NARRATOR: The Sun is a churning cauldron of nuclear reactions. 11 00:00:35,568 --> 00:00:40,406 Revealing its inner workings was once mission impossible. 12 00:00:40,507 --> 00:00:42,107 But not anymore. 13 00:00:42,208 --> 00:00:45,144 We've recruited this network of spies, if you will. 14 00:00:45,245 --> 00:00:47,613 We've built a fleet of spacecraft that 15 00:00:47,714 --> 00:00:50,015 monitor the Sun 24 hours a day. 16 00:00:51,584 --> 00:00:54,253 NARRATOR: With the Sun under close surveillance, 17 00:00:54,354 --> 00:00:57,022 we just might have what it takes to defend our planet. 18 00:01:00,593 --> 00:01:01,460 [explosion] 19 00:01:13,706 --> 00:01:16,942 September 6, 2017. 20 00:01:17,043 --> 00:01:23,182 A flash of ultraviolet and X-ray light erupts from the Sun, 21 00:01:23,283 --> 00:01:26,085 sending a burst of radiation toward Earth. 22 00:01:27,554 --> 00:01:29,488 We call it a solar flare. 23 00:01:30,890 --> 00:01:34,393 Flares are huge explosions on the surface of the Sun, 24 00:01:34,494 --> 00:01:36,995 throwing light out into the solar system 25 00:01:37,097 --> 00:01:39,598 and absolutely baking anything in its path. 26 00:01:39,699 --> 00:01:42,734 These are really powerful events erupting from the Sun. 27 00:01:42,836 --> 00:01:44,603 And we are fundamentally in the line of fire. 28 00:01:47,240 --> 00:01:49,108 NARRATOR: The flare up is so intense it 29 00:01:49,209 --> 00:01:51,543 causes radio blackouts across the side 30 00:01:51,644 --> 00:01:53,345 of the Earth facing the Sun. 31 00:01:55,849 --> 00:01:58,283 And the timing could not have been worse. 32 00:02:01,187 --> 00:02:03,188 The problem was at this time, there 33 00:02:03,289 --> 00:02:06,625 were hurricanes in the Atlantic bearing down on the Caribbean. 34 00:02:06,726 --> 00:02:09,394 And there were people trying to get in there and rescue folks. 35 00:02:12,632 --> 00:02:15,767 NARRATOR: Radio communication between disaster relief teams 36 00:02:15,869 --> 00:02:17,503 goes down for most of the day. 37 00:02:19,372 --> 00:02:23,942 Space weather and Earth weather combined to create chaos. 38 00:02:27,480 --> 00:02:30,015 HAKEEM OLUSEYI: It's not just an academic exercise. 39 00:02:30,116 --> 00:02:33,719 Your very lifestyle depends on understanding 40 00:02:33,820 --> 00:02:34,820 how the Sun behaves. 41 00:02:36,523 --> 00:02:38,157 We need to be able to predict what 42 00:02:38,258 --> 00:02:39,925 the Sun is going to do next. 43 00:02:40,026 --> 00:02:42,694 And in order to do that, we need to have eyes on the Sun, 44 00:02:42,795 --> 00:02:45,230 as many eyes as we can get. 45 00:02:45,331 --> 00:02:49,067 RADIO VOICE: 3, 2, 1. 46 00:02:49,169 --> 00:02:52,671 NARRATOR: That's why NASA has put together an elite unit. 47 00:02:52,772 --> 00:02:54,206 RADIO VOICE: We have ignition. 48 00:02:54,307 --> 00:02:55,974 And we have liftoff. 49 00:02:56,109 --> 00:02:56,875 NEWSCASTER VOICES: Liftoff. 50 00:02:56,976 --> 00:02:58,377 And liftoff. 51 00:02:58,478 --> 00:03:00,546 On an international mission of the solar physics. 52 00:03:01,948 --> 00:03:04,783 NARRATOR: A fleet of daring spacecraft. 53 00:03:04,884 --> 00:03:06,852 We humans have come a long way. 54 00:03:06,953 --> 00:03:09,021 If you go back a few thousand years, 55 00:03:09,122 --> 00:03:10,789 people were worshipping the Sun. 56 00:03:10,890 --> 00:03:14,059 And today, we've built a fleet of spacecraft 57 00:03:14,160 --> 00:03:16,995 that monitor the Sun 24 hours a day, 58 00:03:17,096 --> 00:03:20,032 observing it from every angle, predicting 59 00:03:20,133 --> 00:03:21,633 what it's going to do next. 60 00:03:21,734 --> 00:03:22,434 That's nuts. 61 00:03:24,671 --> 00:03:26,405 NARRATOR: Leading the pack is the Solar 62 00:03:26,506 --> 00:03:28,774 Dynamics Observatory, or SDO. 63 00:03:30,643 --> 00:03:33,412 It keeps a telescopic eye on flares blasting 64 00:03:33,513 --> 00:03:34,446 out from the Sun's surface. 65 00:03:36,849 --> 00:03:40,552 24 hours a day, the probe is on the lookout. 66 00:03:40,653 --> 00:03:42,621 It's constantly vigilant. 67 00:03:42,722 --> 00:03:44,122 PHIL PLAIT: It looks at the Sun and a lot 68 00:03:44,224 --> 00:03:47,259 of different wavelengths in exquisite detail 69 00:03:47,360 --> 00:03:50,462 so that we can see exactly what sort of high-energy events 70 00:03:50,563 --> 00:03:51,630 are happening on the Sun. 71 00:03:53,466 --> 00:03:55,400 NARRATOR: The record for the longest service 72 00:03:55,501 --> 00:04:00,072 goes to SOHO, our sentinel monitoring the Sun 73 00:04:00,173 --> 00:04:03,008 and its faint outer atmosphere. 74 00:04:03,109 --> 00:04:04,443 PHIL PLAIT: The Solar and Heliosphere 75 00:04:04,544 --> 00:04:08,146 Observatory, or SOHO, is the old hand at studying the Sun. 76 00:04:08,248 --> 00:04:10,983 It's been up there for 25 years observing, 77 00:04:11,084 --> 00:04:14,820 not just the Sun itself, but the environment around it. 78 00:04:14,921 --> 00:04:16,655 NINA LANZA: Instead of looking directly at it, 79 00:04:16,756 --> 00:04:18,790 it actually blocks out most of the lights 80 00:04:18,891 --> 00:04:21,126 that we can see all these beautiful structures 81 00:04:21,227 --> 00:04:22,361 that surround the Sun. 82 00:04:25,598 --> 00:04:27,633 NARRATOR: And then there's the new recruit... 83 00:04:27,734 --> 00:04:29,067 The Parker Solar Probe. 84 00:04:31,037 --> 00:04:33,472 Our scout going deep behind enemy lines. 85 00:04:35,141 --> 00:04:36,308 PAUL M. SUTTER: The Parker Solar Probe 86 00:04:36,409 --> 00:04:40,112 is going to give us the closest look at the Sun 87 00:04:40,213 --> 00:04:44,149 that we have ever had in the history of humanity. 88 00:04:44,250 --> 00:04:46,451 DAN DURDA: We're flying so close to the Sun, 89 00:04:46,552 --> 00:04:50,455 we're flying through the gases of its atmosphere. 90 00:04:50,556 --> 00:04:53,325 NARRATOR: 29 other craft make up the fleet, 91 00:04:53,426 --> 00:04:55,994 each with their own role to play. 92 00:04:56,095 --> 00:04:57,996 PHIL PLAIT: This fleet of spacecraft 93 00:04:58,097 --> 00:05:01,166 that we have, the overall mission is to observe the Sun 94 00:05:01,267 --> 00:05:05,337 scientifically, learn about its behavior, but also importantly, 95 00:05:05,438 --> 00:05:08,073 to learn about the effects that it has on Earth. 96 00:05:11,978 --> 00:05:13,545 NARRATOR: Our look-out probe, the Solar 97 00:05:13,646 --> 00:05:17,516 Dynamics Observatory, or SDO, spots something hellish. 98 00:05:21,688 --> 00:05:22,921 PHIL PLAIT: Today's forecast for the Sun 99 00:05:23,022 --> 00:05:25,757 is predicted to be 10,000 degrees Fahrenheit with winds 100 00:05:25,858 --> 00:05:27,359 of up to 600 miles per second. 101 00:05:29,195 --> 00:05:30,996 And a pretty decent chance of rain. 102 00:05:32,398 --> 00:05:33,865 You don't want to be in this rainstorm 103 00:05:33,966 --> 00:05:35,534 because your umbrella isn't going to help you. 104 00:05:37,337 --> 00:05:38,737 Solar rain isn't water. 105 00:05:38,838 --> 00:05:39,971 It's plasma. 106 00:05:40,073 --> 00:05:40,772 Hot plasma. 107 00:05:42,175 --> 00:05:45,911 NARRATOR: Rather than a solid, liquid, or gas, 108 00:05:46,012 --> 00:05:49,848 the entire Sun is made up of a strange fourth state of matter. 109 00:05:51,217 --> 00:05:51,917 Plasma. 110 00:05:58,358 --> 00:06:01,460 MICHELLE THALLER: Plasma is just simply gas that's very hot. 111 00:06:01,561 --> 00:06:03,528 So hot it's lost some of its electrons 112 00:06:03,629 --> 00:06:05,297 and become electrically charged. 113 00:06:05,398 --> 00:06:07,032 And the wonderful thing about plasma 114 00:06:07,133 --> 00:06:08,967 is that once it has that electric charge, 115 00:06:09,068 --> 00:06:10,869 you can direct it with a magnetic field. 116 00:06:12,739 --> 00:06:15,540 NARRATOR: And the Sun has the most powerful magnetic field 117 00:06:15,641 --> 00:06:16,541 in the solar system. 118 00:06:18,244 --> 00:06:20,846 It twists and flows through the entire star. 119 00:06:23,883 --> 00:06:25,016 PHIL PLAIT: The Sun's magnetic field 120 00:06:25,084 --> 00:06:26,618 is incredibly complicated. 121 00:06:26,719 --> 00:06:29,087 There are lots of loops of magnetic lines coming 122 00:06:29,188 --> 00:06:29,921 out of the Sun's surface. 123 00:06:33,793 --> 00:06:35,427 GIBOR BASRI: As you go above the surface, 124 00:06:35,528 --> 00:06:38,997 the magnetic field begins to control where the gas can go, 125 00:06:39,098 --> 00:06:41,900 and you get these beautiful loops and other structures 126 00:06:42,001 --> 00:06:44,302 above the Sun that are just showing you 127 00:06:44,404 --> 00:06:45,470 where the magnetic field is. 128 00:06:48,408 --> 00:06:51,309 NARRATOR: The SDO spacecraft's jaw-dropping videos 129 00:06:51,411 --> 00:06:55,046 of rain on the Sun show plasma flowing along 130 00:06:55,148 --> 00:06:58,617 huge looping magnetic field lines that have punched 131 00:06:58,718 --> 00:06:59,584 through the Sun's surface. 132 00:07:00,987 --> 00:07:03,054 PHIL PLAIT: Because the surface of the Sun is a plasma, 133 00:07:03,156 --> 00:07:05,791 and these loops of magnetic fields are coming out of it, 134 00:07:05,892 --> 00:07:09,127 it draws that plasma up which then cools and rains 135 00:07:09,228 --> 00:07:10,695 down as a plasma rain. 136 00:07:13,466 --> 00:07:15,534 NARRATOR: Tracking these loops of magnetic field 137 00:07:15,635 --> 00:07:18,036 and plasma could help explain solar flares. 138 00:07:21,741 --> 00:07:23,742 And it could give us some warning. 139 00:07:25,778 --> 00:07:29,714 September 2017. 140 00:07:29,816 --> 00:07:34,786 Minutes before the devastating mid-hurricane radio blackout, 141 00:07:34,887 --> 00:07:37,189 our solar lookouts spotted an explosion 142 00:07:37,290 --> 00:07:39,424 on the surface of the Sun. 143 00:07:39,525 --> 00:07:41,960 PHIL PLAIT: Suddenly you have this tremendous flow of energy 144 00:07:42,061 --> 00:07:44,095 and an explosive release of it. 145 00:07:44,197 --> 00:07:46,031 And we call this a solar flare. 146 00:07:46,132 --> 00:07:50,101 This is SDO's specialty of observation. 147 00:07:50,203 --> 00:07:51,970 NARRATOR: The craft tracked the magnetic loops 148 00:07:52,071 --> 00:07:53,038 above the Sun's surface. 149 00:07:55,675 --> 00:07:56,641 They were highly unstable. 150 00:07:59,445 --> 00:08:02,013 SDO takes very detailed pictures 151 00:08:02,114 --> 00:08:03,915 of where the flows are. 152 00:08:04,016 --> 00:08:07,352 You can actually see gas flowing from one place. 153 00:08:07,453 --> 00:08:09,054 You can see the magnetic loops. 154 00:08:11,290 --> 00:08:14,259 This magnetic flux loops are kind of like wires 155 00:08:14,360 --> 00:08:15,527 carrying electricity. 156 00:08:15,661 --> 00:08:17,295 When they're on their own they're fine. 157 00:08:17,396 --> 00:08:20,165 But if they get too close, they can connect and short circuit. 158 00:08:20,266 --> 00:08:22,400 And then you get a tremendous release of energy. 159 00:08:24,904 --> 00:08:26,671 The Ghostbusters were really on to something. 160 00:08:26,772 --> 00:08:27,739 Don't cross the streams. 161 00:08:31,244 --> 00:08:35,113 NARRATOR: The contact between magnetic loops released an epic 162 00:08:35,214 --> 00:08:37,215 explosion of high-energy light. 163 00:08:39,418 --> 00:08:42,354 This radiation altered our planet's atmosphere. 164 00:08:44,757 --> 00:08:47,592 Radio waves jammed, causing blackouts 165 00:08:47,693 --> 00:08:49,160 at the worst possible moment. 166 00:08:51,130 --> 00:08:52,931 PHIL PLAIT: Solar flares are happening on the Sun 167 00:08:53,032 --> 00:08:54,833 90 million miles away. 168 00:08:54,934 --> 00:08:56,201 Who cares, right? 169 00:08:56,302 --> 00:08:57,435 Well, think of it this way. 170 00:08:57,537 --> 00:08:59,271 A really good solar flare could be 171 00:08:59,372 --> 00:09:02,140 the equivalent of, oh, say 10 million 172 00:09:02,241 --> 00:09:04,209 hydrogen bonds going off. 173 00:09:04,310 --> 00:09:05,343 How's that sound? 174 00:09:05,444 --> 00:09:07,746 Solar flares happen a lot. 175 00:09:07,847 --> 00:09:09,180 And they do affect us. 176 00:09:09,282 --> 00:09:11,283 They have affected us in the past. 177 00:09:11,384 --> 00:09:12,517 And they will again in the future. 178 00:09:14,020 --> 00:09:15,921 NARRATOR: But the Sun's twisting magnetic fields 179 00:09:16,022 --> 00:09:18,390 do more than just disrupt our communications. 180 00:09:20,293 --> 00:09:21,793 And when we see flares, we've got 181 00:09:21,894 --> 00:09:23,328 to keep an eye out on those. 182 00:09:23,429 --> 00:09:25,330 But sometimes, there's something even bigger. 183 00:09:27,867 --> 00:09:30,201 NARRATOR: The Sun launches huge clouds of plasma 184 00:09:30,303 --> 00:09:31,503 across the solar system. 185 00:09:33,906 --> 00:09:35,073 PHIL PLAIT: All of that material can 186 00:09:35,174 --> 00:09:37,909 come to the Earth and really mess things up here... 187 00:09:38,010 --> 00:09:41,947 Blow out our power grid, destroy our satellites, even physically 188 00:09:42,048 --> 00:09:43,381 harm our astronauts in orbit. 189 00:09:45,017 --> 00:09:47,452 NARRATOR: Can the solar fleet safeguard Earth? 190 00:09:58,731 --> 00:10:00,966 November 5, 2018. 191 00:10:01,067 --> 00:10:03,535 An explosive cloud of plasma hits 192 00:10:03,636 --> 00:10:06,404 the Parker Solar Probe as it orbits just 193 00:10:06,505 --> 00:10:08,239 15 million miles from the Sun. 194 00:10:11,677 --> 00:10:13,645 We have this fleet of spacecraft 195 00:10:13,746 --> 00:10:15,013 out there viewing the Sun. 196 00:10:15,114 --> 00:10:17,315 And they are also under attack by the Sun. 197 00:10:19,018 --> 00:10:21,987 There are explosions coming from its surface. 198 00:10:22,088 --> 00:10:26,157 Is not just light, but explosions of hot plasma. 199 00:10:26,258 --> 00:10:29,027 And the Parker Solar Probe got blasted. 200 00:10:29,128 --> 00:10:30,462 And yet it survived. 201 00:10:32,732 --> 00:10:34,132 NARRATOR: A huge blast of high-energy 202 00:10:34,233 --> 00:10:37,702 charged particles launches into the solar system 203 00:10:37,803 --> 00:10:39,371 at millions of miles an hour. 204 00:10:41,340 --> 00:10:43,074 A coronal mass ejection. 205 00:10:48,848 --> 00:10:52,117 But our solar scouts is prepared for the onslaught. 206 00:10:52,218 --> 00:10:53,351 PHIL PLAIT: The Parker Solar Probe 207 00:10:53,452 --> 00:10:54,819 gets very close to the Sun. 208 00:10:54,920 --> 00:10:57,055 And it has a heat shield to protect it. 209 00:10:57,156 --> 00:10:59,357 But if it gets hit by a coronal mass ejection, 210 00:10:59,458 --> 00:11:01,826 it has to be protected against that as well. 211 00:11:01,927 --> 00:11:03,862 And so it's been radiation hardened 212 00:11:03,963 --> 00:11:04,996 to survive such an impact. 213 00:11:06,532 --> 00:11:08,900 NARRATOR: Could these blasts pose a danger to our planet? 214 00:11:11,804 --> 00:11:14,105 A coronal mass ejection accelerates 215 00:11:14,206 --> 00:11:15,373 subatomic particles. 216 00:11:15,474 --> 00:11:17,342 And it's not a little bit of particles. 217 00:11:17,443 --> 00:11:20,378 It could be up to a billion tons of them 218 00:11:20,479 --> 00:11:23,782 screaming across the solar system at high speed. 219 00:11:23,883 --> 00:11:27,018 And this is something we need to take very seriously. 220 00:11:29,055 --> 00:11:33,324 NARRATOR: To understand these dangerous blasts of plasma, we 221 00:11:33,426 --> 00:11:34,325 have to look at their source... 222 00:11:36,896 --> 00:11:39,764 An area around the Sun known as the corona. 223 00:11:41,200 --> 00:11:43,735 PHIL PLAIT: The Sun's corona is kind of like its atmosphere. 224 00:11:43,836 --> 00:11:46,671 You can think of the Sun itself as being a ball of gas. 225 00:11:46,772 --> 00:11:50,475 And then outside of that is this ethereally thin gas stretching 226 00:11:50,576 --> 00:11:51,743 out for millions of miles. 227 00:11:53,612 --> 00:11:55,146 NARRATOR: The corona is a difficult thing 228 00:11:55,247 --> 00:11:58,483 to study because the surface of the Sun 229 00:11:58,584 --> 00:12:00,618 is so bright it blocks our view. 230 00:12:02,321 --> 00:12:06,791 We can only see the corona during a total solar eclipse, 231 00:12:06,892 --> 00:12:09,461 when the moon blocks the Sun's bright glare. 232 00:12:11,030 --> 00:12:12,964 Astronomers, though, we're impatient. 233 00:12:13,065 --> 00:12:15,467 We don't want to have to wait for a total solar eclipse, 234 00:12:15,568 --> 00:12:17,802 which only happens once or twice a year. 235 00:12:17,870 --> 00:12:20,638 So we figured out a way to make an artificial one. 236 00:12:20,740 --> 00:12:21,973 And it's really simple. 237 00:12:24,043 --> 00:12:27,579 NARRATOR: One member of the solar fleet has it covered. 238 00:12:27,680 --> 00:12:32,751 Our solar sentinel, SOHO, creates its own eclipse 239 00:12:32,852 --> 00:12:36,488 by obscuring the blinding Sun with a circular plate 240 00:12:36,589 --> 00:12:37,989 in front of the probe's camera. 241 00:12:39,592 --> 00:12:42,694 Sometimes the best solution is the simplest solution. 242 00:12:42,795 --> 00:12:45,730 You know, instead of trying to make a sensor that could 243 00:12:45,831 --> 00:12:49,534 actually see the full dynamic range of the Sun's light, 244 00:12:49,635 --> 00:12:51,936 why not just block out the light that we don't need? 245 00:12:54,273 --> 00:12:57,642 NARRATOR: In July 2012, SOHO spotted 246 00:12:57,743 --> 00:13:00,011 a huge chunk of the corona blasting 247 00:13:00,112 --> 00:13:01,646 off into the solar system. 248 00:13:04,150 --> 00:13:08,486 Seconds earlier, another probe monitoring the solar surface 249 00:13:08,587 --> 00:13:10,088 spotted a bright flare. 250 00:13:12,258 --> 00:13:14,893 Were these events connected? 251 00:13:14,994 --> 00:13:16,494 GIBOR BASRI: If a flare goes off, 252 00:13:16,595 --> 00:13:18,329 it can disrupt those loops. 253 00:13:18,430 --> 00:13:20,632 And if you get the right kind of disruption, 254 00:13:20,733 --> 00:13:22,967 the whole thing can just blow open. 255 00:13:23,068 --> 00:13:25,036 And then you have a tremendous amount 256 00:13:25,137 --> 00:13:28,606 of billions of tons of hydrogen blown 257 00:13:28,707 --> 00:13:31,176 off into interplanetary space. 258 00:13:31,277 --> 00:13:33,011 And that's a coronal mass ejection. 259 00:13:35,781 --> 00:13:39,050 NARRATOR: Coronal mass ejections are solar flares on steroids. 260 00:13:40,653 --> 00:13:42,887 If a solar flare was a firecracker, 261 00:13:42,988 --> 00:13:45,356 coronal mass ejection is more like an atom bomb. 262 00:13:52,498 --> 00:13:56,100 NARRATOR: And if a coronal mass ejection comes our way, 263 00:13:56,168 --> 00:13:58,036 it hits hard. 264 00:13:58,137 --> 00:14:00,471 The first thing it does is it compresses 265 00:14:00,573 --> 00:14:02,006 Earth's magnetic field. 266 00:14:02,107 --> 00:14:04,308 And then it wraps around the Earth. 267 00:14:04,376 --> 00:14:07,612 And this causes the magnetic field itself to rearrange, 268 00:14:07,713 --> 00:14:10,415 reconnect, and streams of particles 269 00:14:10,516 --> 00:14:13,618 travel down those magnetic fields toward our poles 270 00:14:13,719 --> 00:14:15,353 and impact the atmosphere. 271 00:14:15,454 --> 00:14:16,688 Our shields are up. 272 00:14:16,789 --> 00:14:19,190 But they are able to penetrate our shields. 273 00:14:19,291 --> 00:14:22,160 Our shield being our own magnetic field. 274 00:14:22,261 --> 00:14:24,028 NARRATOR: Once they breach our defenses, 275 00:14:24,129 --> 00:14:27,765 the particles of a coronal mass ejection can wreak havoc. 276 00:14:30,669 --> 00:14:34,739 In August of 1972, tensions were running high in Vietnam. 277 00:14:36,609 --> 00:14:40,912 [bombs exploding] 278 00:14:41,013 --> 00:14:43,915 Two dozen sea mines detonated at the same time 279 00:14:44,016 --> 00:14:45,783 when their magnetic sensors were tripped. 280 00:14:45,885 --> 00:14:49,387 A satellite was lost because of the electromagnetic pulse 281 00:14:49,488 --> 00:14:50,989 that ripped through it. 282 00:14:51,090 --> 00:14:53,424 And an Air Force sensor detected 283 00:14:53,525 --> 00:14:55,693 what looked like a nuclear explosion 284 00:14:55,794 --> 00:14:57,729 somewhere here on the planet. 285 00:14:57,830 --> 00:14:59,297 NARRATOR: Fortunately, scientists 286 00:14:59,398 --> 00:15:00,932 quickly found the real culprit. 287 00:15:03,335 --> 00:15:05,370 A coronal mass ejection had ripped 288 00:15:05,471 --> 00:15:07,338 through the Earth's magnetic field 289 00:15:07,439 --> 00:15:08,806 and triggered magnetic sensors. 290 00:15:11,176 --> 00:15:13,511 The crisis soon de-escalated. 291 00:15:15,881 --> 00:15:18,616 PHIL PLAIT: The Sun is an immense ball of plasma 292 00:15:18,717 --> 00:15:21,586 860,000 miles across. 293 00:15:21,687 --> 00:15:23,821 We are not going to be able to stop it from doing 294 00:15:23,923 --> 00:15:25,356 whatever it wants to do. 295 00:15:25,457 --> 00:15:29,994 What we can do is learn to predict what's going to happen. 296 00:15:30,095 --> 00:15:31,229 So we're doing that now. 297 00:15:36,201 --> 00:15:38,069 NARRATOR: Our new fleet of solar observers 298 00:15:38,170 --> 00:15:39,537 are our first line of defense. 299 00:15:43,642 --> 00:15:44,742 PHIL PLAIT: The Sun is a little over 300 00:15:44,843 --> 00:15:46,477 90 million miles from Earth. 301 00:15:46,578 --> 00:15:48,479 It takes light a little over eight minutes 302 00:15:48,580 --> 00:15:50,148 to get from there to here. 303 00:15:50,249 --> 00:15:53,184 As rapidly as a coronal mass ejection is traveling, 304 00:15:53,285 --> 00:15:55,987 it still takes a few days to get here. 305 00:15:58,557 --> 00:16:01,993 We can watch the Sun to see is there going to be an event, 306 00:16:02,094 --> 00:16:03,394 or is an event starting? 307 00:16:03,495 --> 00:16:05,229 And these satellites can then tell 308 00:16:05,331 --> 00:16:06,798 us, hey, you better be careful. 309 00:16:06,899 --> 00:16:08,900 You might need to batten down the hatches on Earth. 310 00:16:12,304 --> 00:16:13,938 NARRATOR: But there may be an earlier clue 311 00:16:14,039 --> 00:16:15,373 the fleet can watch out for. 312 00:16:16,742 --> 00:16:21,012 Vast, dark regions moving across the solar surface 313 00:16:21,113 --> 00:16:21,779 called sunspots. 314 00:16:23,582 --> 00:16:24,682 HAKEEM OLUSEYI: We know that this is 315 00:16:24,783 --> 00:16:26,617 the wind up before the release. 316 00:16:26,719 --> 00:16:28,619 This thing is getting ready to blow. 317 00:16:41,333 --> 00:16:45,069 NARRATOR: In March of 1989, a solar eruption 318 00:16:45,170 --> 00:16:50,641 caused blackouts across Canada and malfunctions 319 00:16:50,743 --> 00:16:51,943 on board the space shuttle. 320 00:16:53,278 --> 00:16:55,013 RADIO VOICE: We've been seeing some erratic pressure 321 00:16:55,114 --> 00:16:58,282 signatures out of tank 3, as well as some manifold pressure 322 00:16:58,384 --> 00:16:59,517 spikes in that system. 323 00:17:01,453 --> 00:17:03,187 NARRATOR: 11 years later, the Sun 324 00:17:03,288 --> 00:17:06,557 emitted a flare that was so powerful it blinded 325 00:17:06,658 --> 00:17:07,759 the solar fleet's sensors. 326 00:17:10,462 --> 00:17:13,197 11 years after that, the Earth had 327 00:17:13,298 --> 00:17:15,933 a near-miss with the most powerful coronal mass 328 00:17:16,035 --> 00:17:17,335 ejection ever recorded. 329 00:17:21,073 --> 00:17:23,307 The Sun has a very predictable, but actually quite 330 00:17:23,409 --> 00:17:25,343 mysterious cycle of activity. 331 00:17:25,444 --> 00:17:27,779 It gets very, very active every 11 years. 332 00:17:27,880 --> 00:17:30,848 And then it settles back down to more of a peaceful existence. 333 00:17:32,418 --> 00:17:34,419 NARRATOR: This 11-year cycle has astronomers 334 00:17:34,520 --> 00:17:35,486 scratching their heads. 335 00:17:37,489 --> 00:17:40,525 One thing we do know is that violent solar events 336 00:17:40,626 --> 00:17:44,595 seem to be preceded by dark patches on the solar surface. 337 00:17:46,732 --> 00:17:48,199 Sunspots. 338 00:17:48,300 --> 00:17:50,535 HAKEEM OLUSEYI: Sunspots are large areas on the surface 339 00:17:50,636 --> 00:17:52,537 of the Sun, much bigger than the Earth, 340 00:17:52,638 --> 00:17:57,008 that are caused by incredibly strong magnetic fields 341 00:17:57,109 --> 00:17:58,643 disrupting the flow of plasma. 342 00:18:00,245 --> 00:18:02,814 NARRATOR: And every 11 years, these dark spots 343 00:18:02,915 --> 00:18:08,052 grow in number like clouds gathering before a storm. 344 00:18:10,689 --> 00:18:12,623 When you start seeing more and more sunspots, 345 00:18:12,724 --> 00:18:13,991 there's an expectation that you're 346 00:18:14,093 --> 00:18:16,761 going to see more intense and more frequent solar flares. 347 00:18:20,632 --> 00:18:22,633 NARRATOR: But what drives this 11-year cycle? 348 00:18:24,002 --> 00:18:25,470 It's kind of ironic that one of the most 349 00:18:25,571 --> 00:18:28,439 predictable things about the Sun is also the most mysterious. 350 00:18:30,342 --> 00:18:33,411 PAUL M. SUTTER: We've been puzzling over the sunspot cycle 351 00:18:33,512 --> 00:18:35,446 for generations. 352 00:18:35,547 --> 00:18:39,283 And now finally we have spacecraft headed to the Sun 353 00:18:39,384 --> 00:18:40,751 to try to give us some answers. 354 00:18:42,754 --> 00:18:45,456 NARRATOR: The SOHO, SDO, and STEREO spacecraft 355 00:18:45,557 --> 00:18:49,227 monitor the Sun's atmosphere using ultraviolet telescopes. 356 00:18:51,363 --> 00:18:54,832 They spot flashes of high-energy ultraviolet light 357 00:18:54,933 --> 00:18:56,167 moving across the Sun. 358 00:19:00,339 --> 00:19:02,273 These waves of light could be connected 359 00:19:02,374 --> 00:19:09,580 to the cycle of sunspots and to the Sun's outbursts. 360 00:19:09,681 --> 00:19:11,649 Because everything we see on the Sun's 361 00:19:11,750 --> 00:19:17,255 surface is controlled by violent processes deep in its interior. 362 00:19:21,260 --> 00:19:24,762 The Sun is a very simple onion. 363 00:19:24,863 --> 00:19:27,198 At the very, very center is the core where 364 00:19:27,299 --> 00:19:29,133 the nuclear fusion happens. 365 00:19:29,234 --> 00:19:31,469 A layer surrounding that is known 366 00:19:31,570 --> 00:19:34,872 as the radiative zone, where most of the energy gets 367 00:19:34,973 --> 00:19:37,108 pushed out through radiation. 368 00:19:37,209 --> 00:19:39,510 Then surrounding that is something 369 00:19:39,611 --> 00:19:42,013 called the convective zone, where there's 370 00:19:42,114 --> 00:19:45,416 great plumes and chains of plasma moving 371 00:19:45,517 --> 00:19:48,286 up and down, up and down. 372 00:19:48,387 --> 00:19:51,422 NARRATOR: But unlike an onion, the layers spin. 373 00:19:54,226 --> 00:19:56,060 MICHELLE THALLER: There are currents inside the Sun 374 00:19:56,161 --> 00:19:57,962 we don't see from the surface. 375 00:19:58,063 --> 00:19:59,897 Layers of the Sun deep down inside 376 00:19:59,998 --> 00:20:02,033 are rotating at different rates than the layers above. 377 00:20:03,435 --> 00:20:05,903 GIBOR BASRI: So it turns out the inner part of the Sun 378 00:20:06,004 --> 00:20:08,539 is rotating at maybe three times more 379 00:20:08,640 --> 00:20:11,042 rapidly than the outer part of the Sun. 380 00:20:11,176 --> 00:20:13,044 We also can see on the outer part of the Sun 381 00:20:13,145 --> 00:20:16,714 that the equator is rotating more rapidly than the pole. 382 00:20:19,651 --> 00:20:22,320 NARRATOR: These layers of plasma grinding against each other 383 00:20:22,421 --> 00:20:27,525 generate the Sun's enormously powerful magnetic field 384 00:20:27,626 --> 00:20:31,729 and give rise to sunspots, plasma loops, and solar flares. 385 00:20:33,832 --> 00:20:36,601 This differential rotation takes the field 386 00:20:36,702 --> 00:20:39,203 and starts twisting it around the Sun. 387 00:20:39,304 --> 00:20:41,739 So as the magnetic field gets too twisted, 388 00:20:41,840 --> 00:20:42,940 it starts knotting up. 389 00:20:43,041 --> 00:20:45,376 And these knots start bubbling up to the surface. 390 00:20:45,477 --> 00:20:47,511 And that's what we're seeing actually with the sunspots. 391 00:20:49,147 --> 00:20:51,082 And that's why you see all these wonderful loops 392 00:20:51,183 --> 00:20:53,050 and prominences coming off the Sun. 393 00:20:53,151 --> 00:20:55,853 Once the magnetic fields start twisting and interacting, 394 00:20:55,954 --> 00:20:59,023 they can direct the plasma into vast rivers and loops 395 00:20:59,124 --> 00:21:01,058 both above and below the surface of the Sun. 396 00:21:05,397 --> 00:21:08,866 NARRATOR: Why these events flare up every 11 years is a mystery. 397 00:21:10,902 --> 00:21:14,071 But now new observations from the solar fleet 398 00:21:14,172 --> 00:21:17,341 could provide a clue about what triggers the solar cycle. 399 00:21:19,378 --> 00:21:23,414 Giant, moving magnetic fields beneath the Sun's surface. 400 00:21:26,285 --> 00:21:29,487 We think that the ultraviolet light flickers are telling 401 00:21:29,588 --> 00:21:31,822 us where the magnetic field is. 402 00:21:33,258 --> 00:21:34,759 In the course of the 11-year cycle, 403 00:21:34,860 --> 00:21:36,727 the Sun's magnetic fields begin to move 404 00:21:36,828 --> 00:21:40,931 down from the poles closer and closer to the equator. 405 00:21:41,033 --> 00:21:43,934 NARRATOR: As the magnetic field lines move through the star, 406 00:21:44,036 --> 00:21:46,170 they carry huge amounts of plasma with them. 407 00:21:48,774 --> 00:21:53,344 The magnetic field lines act like shepherds for the plasma 408 00:21:53,445 --> 00:21:55,079 underneath the surface. 409 00:21:55,180 --> 00:21:58,182 And they push plasma down to the equator of the Sun. 410 00:21:59,951 --> 00:22:02,953 NARRATOR: The magnetic fields trap enormous amounts 411 00:22:03,055 --> 00:22:07,224 of plasma, like water behind a dam, 412 00:22:07,326 --> 00:22:09,694 until eventually the floodgates open, 413 00:22:09,795 --> 00:22:11,896 and the plasma comes rushing out. 414 00:22:15,334 --> 00:22:17,802 When the magnetic fields meet, they cancel each other out 415 00:22:17,903 --> 00:22:21,505 and release the plasma, which goes as a tsunami wave 416 00:22:21,606 --> 00:22:22,573 back to the polls. 417 00:22:24,609 --> 00:22:25,910 MICHELLE THALLER: When that plasma 418 00:22:26,011 --> 00:22:28,279 rebounds from the equator and hits the magnetic field coming 419 00:22:28,380 --> 00:22:30,147 down from the poles at the mid latitudes, 420 00:22:30,248 --> 00:22:33,818 you get a huge burst of magnetic activity. 421 00:22:33,919 --> 00:22:37,421 NARRATOR: Magnetic activity that triggers sunspots and loops. 422 00:22:37,522 --> 00:22:39,523 Also explains the 11-year cycle. 423 00:22:43,428 --> 00:22:45,696 We think that this relationship between 424 00:22:45,797 --> 00:22:48,366 the magnetic fields, the ultraviolet flickers, 425 00:22:48,467 --> 00:22:52,002 and the plasma drives the 11-year cycle. 426 00:22:52,104 --> 00:22:55,039 We think this is what's actually doing the work. 427 00:22:56,908 --> 00:23:00,344 NARRATOR: The solar cycle has wound down for now. 428 00:23:00,445 --> 00:23:04,749 But once the next plasma tsunami rushes through the Sun, 429 00:23:04,850 --> 00:23:07,785 our star will kick start into action again. 430 00:23:09,187 --> 00:23:10,721 Over the next few years, we're going 431 00:23:10,822 --> 00:23:15,092 to start to see more sunspots, more activity, more flares, 432 00:23:15,193 --> 00:23:17,895 more ejections, and more space weather 433 00:23:17,996 --> 00:23:18,829 that we have to deal with. 434 00:23:20,866 --> 00:23:24,068 NARRATOR: Our fleet of solar spies is poised and ready. 435 00:23:28,573 --> 00:23:30,908 But flares and coronal mass ejections 436 00:23:31,009 --> 00:23:33,177 are not the only solar attacks we have 437 00:23:33,278 --> 00:23:34,478 to shield ourselves against. 438 00:23:36,214 --> 00:23:38,516 There's a strange, invisible force 439 00:23:38,617 --> 00:23:41,886 flowing through the entire solar system. 440 00:23:41,987 --> 00:23:43,654 There is this great wind of high-energy 441 00:23:43,755 --> 00:23:44,622 particles from the Sun. 442 00:23:44,723 --> 00:23:46,123 A million mile-an-hour wind. 443 00:23:47,993 --> 00:23:49,393 NARRATOR: And it can be deadly. 444 00:23:53,465 --> 00:23:54,365 [explosion] 445 00:24:04,443 --> 00:24:09,213 In November 2019, the solar fleet watched as Mercury 446 00:24:09,314 --> 00:24:10,548 sailed across the Sun. 447 00:24:13,819 --> 00:24:15,386 JESSIE CHRISTIANSEN: Mercury is the closest planet 448 00:24:15,487 --> 00:24:17,021 to our Sun in our solar system. 449 00:24:17,122 --> 00:24:18,722 So it's on the front line receiving 450 00:24:18,824 --> 00:24:19,957 all of this radiation. 451 00:24:20,058 --> 00:24:21,725 An incredible amount of energy. 452 00:24:21,793 --> 00:24:23,027 And it's such a tiny planet. 453 00:24:24,463 --> 00:24:26,831 NARRATOR: Temperatures on the innermost planet's surface 454 00:24:26,932 --> 00:24:29,467 reach 800 degrees Fahrenheit. 455 00:24:30,902 --> 00:24:33,204 But scientists discovered something unexpected 456 00:24:33,305 --> 00:24:34,004 on Mercury. 457 00:24:35,941 --> 00:24:39,009 Frozen pools of water hidden in its craters. 458 00:24:41,813 --> 00:24:43,681 It's one of the last places in the solar system you might 459 00:24:43,782 --> 00:24:45,983 expect to find ice, on Mercury, one of the hottest 460 00:24:46,084 --> 00:24:47,852 planets in the solar system. 461 00:24:47,953 --> 00:24:49,820 KEVIN WALSH: Despite the overall really 462 00:24:49,921 --> 00:24:52,056 high temperatures across the whole planet, 463 00:24:52,157 --> 00:24:53,824 there are regions... 464 00:24:53,925 --> 00:24:55,559 Typically deep within craters... 465 00:24:55,660 --> 00:24:57,194 That are permanently shadowed. 466 00:24:57,295 --> 00:25:00,698 So there's never direct sunlight on those regions of Mercury. 467 00:25:00,799 --> 00:25:05,169 And you can keep things as cold as ice in those craters. 468 00:25:05,270 --> 00:25:07,071 NARRATOR: But where did the ice come from? 469 00:25:08,406 --> 00:25:10,374 When we first saw that there was ice on Mercury, 470 00:25:10,475 --> 00:25:12,343 we thought something must have brought it there. 471 00:25:12,444 --> 00:25:14,745 Something like a comet, which is made out of ice. 472 00:25:16,381 --> 00:25:18,349 But there's a new idea that maybe 473 00:25:18,450 --> 00:25:21,552 the materials that make this ice are 474 00:25:21,653 --> 00:25:23,454 actually coming from the Sun. 475 00:25:26,691 --> 00:25:28,859 NARRATOR: The Sun creating ice sounds strange. 476 00:25:30,328 --> 00:25:34,098 But recent research shows it's not as crazy as it seems. 477 00:25:35,734 --> 00:25:37,735 MICHELLE THALLER: We often think of space as being empty. 478 00:25:37,836 --> 00:25:41,138 But in fact, we are bathed in a wind, a million 479 00:25:41,239 --> 00:25:43,541 mile-an-hour wind of high-energy particles from the Sun 480 00:25:43,642 --> 00:25:44,408 all the time. 481 00:25:44,509 --> 00:25:45,209 The solar wind. 482 00:25:48,179 --> 00:25:50,014 NARRATOR: A stream of subatomic particles 483 00:25:50,115 --> 00:25:52,850 called protons constantly flow out 484 00:25:52,951 --> 00:25:58,022 from the Sun in all directions, bombarding the planets 485 00:25:58,123 --> 00:25:58,989 of our solar system. 486 00:26:03,228 --> 00:26:06,096 CARLY HOWETT: The solar wind is so strong when it hits Mercury 487 00:26:06,197 --> 00:26:07,765 that it can break down some of the minerals 488 00:26:07,866 --> 00:26:10,968 and rocks on its surface into their constituent parts. 489 00:26:11,069 --> 00:26:14,405 And those parts, especially if they have oxygen in them, 490 00:26:14,506 --> 00:26:17,508 can go to reform and form water, which 491 00:26:17,609 --> 00:26:20,144 if it forms in the right place, can then stick around. 492 00:26:22,614 --> 00:26:25,649 NARRATOR: Protons in the solar wind combined with oxygen 493 00:26:25,750 --> 00:26:28,052 to form water molecules. 494 00:26:28,153 --> 00:26:30,521 They condense and freeze in craters 495 00:26:30,622 --> 00:26:31,555 which never see sunlight. 496 00:26:34,626 --> 00:26:38,362 So even on the Sun's closest neighbor, ice builds up. 497 00:26:40,899 --> 00:26:43,367 But the solar wind doesn't stop at Mercury. 498 00:26:47,038 --> 00:26:49,139 The solar wind has a tremendous impact 499 00:26:49,240 --> 00:26:51,809 on the world's of our solar system. 500 00:26:51,910 --> 00:26:53,777 We think it's responsible for the planet Venus 501 00:26:53,878 --> 00:26:55,512 becoming this hell hole of heat. 502 00:26:57,449 --> 00:27:01,719 NARRATOR: Up until as recently as 700 million years ago, 503 00:27:01,820 --> 00:27:04,822 Venus was a lush water world with conditions 504 00:27:04,923 --> 00:27:05,856 suitable for life. 505 00:27:07,959 --> 00:27:11,695 But the solar wind blasted away the water vapor and oxygen 506 00:27:11,796 --> 00:27:17,167 from Venus's atmosphere, leaving carbon dioxide to dominate, 507 00:27:17,268 --> 00:27:19,637 trapping the Sun's heat, and causing surface 508 00:27:19,738 --> 00:27:21,138 temperatures to skyrocket. 509 00:27:23,608 --> 00:27:25,609 Mars was once habitable too. 510 00:27:27,312 --> 00:27:30,781 But the solar wind quickly took care of that as well. 511 00:27:33,318 --> 00:27:34,852 PAUL M. SUTTER: We believe that billions of years 512 00:27:34,953 --> 00:27:39,123 ago, Mars had an atmosphere, and it had oceans, and rivers. 513 00:27:39,224 --> 00:27:40,190 It looked a lot like Earth. 514 00:27:40,291 --> 00:27:41,625 It was gorgeous. 515 00:27:41,726 --> 00:27:46,397 But that solar wind stripped away the Martian atmosphere 516 00:27:46,498 --> 00:27:49,199 and turned it into the barren wasteland that it is today. 517 00:27:51,302 --> 00:27:54,371 NARRATOR: And Earth is in the line of fire too. 518 00:27:54,472 --> 00:27:58,208 It's bombarded every day with solar wind particles. 519 00:28:00,178 --> 00:28:02,112 So how has life survived? 520 00:28:03,348 --> 00:28:04,481 MICHELLE THALLER: One of the things we really 521 00:28:04,582 --> 00:28:06,250 take for granted is how well protected 522 00:28:06,351 --> 00:28:07,651 we are here on the Earth. 523 00:28:07,752 --> 00:28:10,421 The atmosphere absorbs a lot of harmful things from space 524 00:28:10,522 --> 00:28:11,655 and from the Sun as well. 525 00:28:11,756 --> 00:28:13,657 But also our magnetic field deflects 526 00:28:13,758 --> 00:28:14,958 the solar wind around us. 527 00:28:15,060 --> 00:28:16,593 And we still have an atmosphere. 528 00:28:18,396 --> 00:28:21,098 And when the charged particles come from the Sun, 529 00:28:21,199 --> 00:28:22,599 the magnetic field lines trap those 530 00:28:22,701 --> 00:28:24,501 charged particles and redirect them 531 00:28:24,602 --> 00:28:26,203 to the poles of the planet. 532 00:28:26,304 --> 00:28:28,472 PHIL PLAIT: The physical effect, the direct physical effect, 533 00:28:28,573 --> 00:28:30,441 of getting bombarded by these particles, 534 00:28:30,542 --> 00:28:33,610 they can generate the Aurora borealis, the Northern Lights. 535 00:28:33,712 --> 00:28:36,447 And these are spectacular and beautiful. 536 00:28:37,882 --> 00:28:40,584 NARRATOR: Auroras are beautiful. 537 00:28:40,685 --> 00:28:44,354 But they're also the front line in the battle between Earth 538 00:28:44,456 --> 00:28:46,657 and the solar wind. 539 00:28:46,758 --> 00:28:49,093 Without our protective shield, we'd suffer 540 00:28:49,194 --> 00:28:51,462 the same fate as Venus or Mars. 541 00:28:53,264 --> 00:28:56,867 But there is a mystery surrounding the solar wind. 542 00:28:56,968 --> 00:28:58,702 One of the things we know about the solar wind 543 00:28:58,803 --> 00:29:00,738 is that it is hugely energetic. 544 00:29:00,839 --> 00:29:02,339 A million miles-an-hour. 545 00:29:02,440 --> 00:29:03,540 What gives it that energy? 546 00:29:05,210 --> 00:29:08,512 NARRATOR: Astronomers think the source of the solar wind 547 00:29:08,646 --> 00:29:13,617 lies in the inner corona, the atmosphere of the Sun revealed 548 00:29:13,718 --> 00:29:15,586 by our solar sentinel, SOHO. 549 00:29:17,555 --> 00:29:20,491 SOHO's data shows that near the Sun's surface, 550 00:29:20,592 --> 00:29:22,593 the wind speed is close to zero. 551 00:29:25,130 --> 00:29:28,031 But by the time the win gets to the outer corona, 552 00:29:28,133 --> 00:29:33,904 it accelerates to 720,000 miles-an-hour. 553 00:29:34,005 --> 00:29:36,774 Something happens mysterious between the surface of the Sun 554 00:29:36,875 --> 00:29:39,409 and the corona that gives a punch to the solar wind. 555 00:29:41,246 --> 00:29:44,548 NARRATOR: To investigate, we need to visit the corona. 556 00:29:46,050 --> 00:29:50,420 So NASA sent a scout on a daring mission behind enemy lines. 557 00:29:53,424 --> 00:29:55,993 The Parker Solar Probe, that's a daredevil. 558 00:29:56,094 --> 00:29:58,962 This is designed to dive bomb the Sun. 559 00:30:03,701 --> 00:30:03,801 [explosion] 560 00:30:12,110 --> 00:30:14,344 NARRATOR: The Sun exerts a hostile influence 561 00:30:14,445 --> 00:30:16,280 on the planets of our solar system. 562 00:30:18,983 --> 00:30:19,683 The solar wind. 563 00:30:21,152 --> 00:30:22,186 It's fast. 564 00:30:22,287 --> 00:30:23,921 It's lethal. 565 00:30:24,022 --> 00:30:27,157 But we don't know how it works. 566 00:30:27,258 --> 00:30:29,059 MICHELLE THALLER: We have spacecraft between us 567 00:30:29,160 --> 00:30:31,161 and the Sun that can actually see what's coming towards us 568 00:30:31,262 --> 00:30:32,596 and how it will impact us. 569 00:30:32,697 --> 00:30:35,032 But what scientists have never been able to explain 570 00:30:35,133 --> 00:30:39,069 is what actually accelerates the wind away from the Sun. 571 00:30:39,170 --> 00:30:41,338 This has been one of the biggest mysteries of the Sun so far. 572 00:30:43,741 --> 00:30:45,943 NARRATOR: For decades, we had no way of solving it. 573 00:30:47,812 --> 00:30:48,512 Until now. 574 00:30:50,582 --> 00:30:52,182 There really are some of these wonderful moments 575 00:30:52,283 --> 00:30:53,517 when you're a scientist. 576 00:30:53,618 --> 00:30:56,720 And I was actually at the launch of the Parker Solar Probe, 577 00:30:56,821 --> 00:30:58,856 standing right next to Dr. Eugene Parker, 578 00:30:58,957 --> 00:31:00,424 who the probe is named after. 579 00:31:00,525 --> 00:31:03,427 NEWSCASTER VOICE: Liftoff of the Parker Solar Probe. 580 00:31:03,528 --> 00:31:04,962 MICHELLE THALLER: Long ago, he had proposed 581 00:31:05,063 --> 00:31:06,830 the Sun probably had a wind of particles 582 00:31:06,931 --> 00:31:08,131 that affected the Earth. 583 00:31:08,233 --> 00:31:10,100 And people basically laughed at him. 584 00:31:10,201 --> 00:31:11,869 But he was proven right over time. 585 00:31:11,970 --> 00:31:15,472 And as that giant delta rocket slowly went up from the pad, 586 00:31:15,573 --> 00:31:18,475 he and I both got to be bathed in that light, and smile. 587 00:31:21,646 --> 00:31:24,348 There has been no spacecraft ever 588 00:31:24,449 --> 00:31:27,484 in human history to fly through the corona, 589 00:31:27,585 --> 00:31:30,520 the very atmosphere of the Sun. 590 00:31:30,622 --> 00:31:32,222 GIBOR BASRI: Didn't work out well for Icarus. 591 00:31:32,323 --> 00:31:34,758 And we hope it works out well for Parker. 592 00:31:34,859 --> 00:31:36,360 The thing about going near the Sun 593 00:31:36,461 --> 00:31:40,564 is, the closer you go to it, the closer your temperature gets 594 00:31:40,665 --> 00:31:42,366 to its surface temperature. 595 00:31:42,467 --> 00:31:44,801 And its surface temperature is 6,000 degrees, 596 00:31:44,903 --> 00:31:46,637 which vaporizes metal easily. 597 00:31:49,440 --> 00:31:52,075 NARRATOR: Surviving close to the Sun is a big ask. 598 00:31:53,645 --> 00:31:54,978 But reaching the Sun? 599 00:31:55,079 --> 00:31:57,915 That's an even bigger challenge. 600 00:31:58,016 --> 00:31:59,116 It's very hot. 601 00:31:59,217 --> 00:32:01,485 It tends to melt your spacecraft. 602 00:32:01,586 --> 00:32:02,953 That's the obvious problem. 603 00:32:03,054 --> 00:32:06,189 A less obvious problem is it's just hard to get there. 604 00:32:06,291 --> 00:32:08,592 This is something I think that it's very hard for most people 605 00:32:08,693 --> 00:32:10,560 to grasp. 606 00:32:10,662 --> 00:32:11,895 There have been suggestions of, you 607 00:32:11,996 --> 00:32:14,197 know, let's send all our nuclear waste into the Sun, 608 00:32:14,299 --> 00:32:15,999 or our trash, or whatever. 609 00:32:16,100 --> 00:32:18,535 And it turns out to be very difficult to drop 610 00:32:18,636 --> 00:32:19,636 anything into the Sun. 611 00:32:21,506 --> 00:32:23,006 NARRATOR: The reason is the Earth 612 00:32:23,074 --> 00:32:28,378 is circling around the Sun at 67,000 miles-an-hour. 613 00:32:28,479 --> 00:32:31,815 That's good because that means we don't drop in to the Sun. 614 00:32:31,916 --> 00:32:33,517 We stay at the same distance. 615 00:32:33,618 --> 00:32:35,285 But if you do want to drop into the Sun, 616 00:32:35,386 --> 00:32:36,820 you'd have to lose that velocity. 617 00:32:36,921 --> 00:32:38,155 And that's a lot of velocity. 618 00:32:40,591 --> 00:32:43,093 NARRATOR: To lose speed the Parker Solar Probe 619 00:32:43,194 --> 00:32:48,432 swings by Venus, performing a gravitational slingshot 620 00:32:48,533 --> 00:32:49,199 in reverse. 621 00:32:50,935 --> 00:32:52,970 MICHELLE THALLER: Now usually, a gravitational slingshot 622 00:32:53,071 --> 00:32:54,771 gives us more velocity. 623 00:32:54,872 --> 00:32:57,040 So if we're flying out to Pluto, for example, 624 00:32:57,141 --> 00:32:59,576 we might whip the spacecraft around the planet Jupiter. 625 00:32:59,677 --> 00:33:02,879 It actually takes the spacecraft and gravitationally slingshots 626 00:33:02,981 --> 00:33:05,282 it forward, making go faster. 627 00:33:05,383 --> 00:33:07,017 The thing that we have to do with Parker Solar Probe 628 00:33:07,118 --> 00:33:08,251 is the opposite. 629 00:33:08,319 --> 00:33:10,020 We're going to use a gravitational slingshot, 630 00:33:10,121 --> 00:33:11,355 but not to speed it up... 631 00:33:11,456 --> 00:33:12,155 To slow it down. 632 00:33:13,725 --> 00:33:15,726 NARRATOR: Parker's gravitational maneuvers 633 00:33:15,827 --> 00:33:18,962 send the craft on a trajectory inside the Sun's 634 00:33:19,063 --> 00:33:24,001 extended corona, closer to the Sun 635 00:33:24,102 --> 00:33:27,137 than any spacecraft before it. 636 00:33:27,238 --> 00:33:31,074 This probe actually dives really deep toward the Sun. 637 00:33:31,175 --> 00:33:34,945 So it's actually going through some of these coronal material 638 00:33:35,046 --> 00:33:37,047 and can actually observe it directly in a way 639 00:33:37,148 --> 00:33:38,115 that other probes can't. 640 00:33:41,152 --> 00:33:44,221 NARRATOR: Using its extreme ultraviolet telescope, 641 00:33:44,322 --> 00:33:46,857 Parker spots vast, dark regions below. 642 00:33:50,028 --> 00:33:51,228 There's really interesting regions 643 00:33:51,329 --> 00:33:53,397 called coronal holes where you can see 644 00:33:53,498 --> 00:33:55,265 literally deeper into the Sun. 645 00:33:56,901 --> 00:34:00,037 NARRATOR: Coronal holes are areas of the Sun's coronavirus 646 00:34:00,138 --> 00:34:02,773 where the atmosphere is cooler and less dense. 647 00:34:05,576 --> 00:34:09,980 And when the probe passes over a hole in the coronavirus it 648 00:34:10,081 --> 00:34:11,648 gets a bigger blast of the solar wind. 649 00:34:13,184 --> 00:34:14,651 NARRATOR: These coronal holes appear to be 650 00:34:14,752 --> 00:34:16,153 the source of the solar wind. 651 00:34:18,322 --> 00:34:19,756 And we think it's through these holes 652 00:34:19,857 --> 00:34:21,792 that the solar wind is able to escape the Sun. 653 00:34:23,194 --> 00:34:24,728 NARRATOR: The big question is, how 654 00:34:24,829 --> 00:34:28,198 does the solar wind actually accelerate away from the Sun? 655 00:34:29,667 --> 00:34:31,001 It seems to defy logic. 656 00:34:33,271 --> 00:34:35,739 You would think that as something leaves the source, 657 00:34:35,840 --> 00:34:37,874 it would probably start to slow down, or at least 658 00:34:37,975 --> 00:34:39,076 stay the same speed. 659 00:34:39,177 --> 00:34:40,077 But this doesn't. 660 00:34:40,178 --> 00:34:40,877 It gets faster. 661 00:34:42,513 --> 00:34:44,681 MICHELLE THALLER: Something is accelerating the solar wind. 662 00:34:44,782 --> 00:34:46,850 It gets faster and hotter as it moves away 663 00:34:46,951 --> 00:34:48,151 from the surface of the Sun. 664 00:34:48,252 --> 00:34:49,686 And the mechanism is a mystery. 665 00:34:51,489 --> 00:34:53,623 NARRATOR: To solve the mystery, our solar scout 666 00:34:53,724 --> 00:34:55,158 dives close to the Sun... 667 00:34:57,095 --> 00:35:00,530 Not to see what's going on, but to listen. 668 00:35:00,631 --> 00:35:01,965 [strange noises] 669 00:35:15,780 --> 00:35:18,281 That sounded spooky. 670 00:35:18,382 --> 00:35:20,083 That sounded really spooky. 671 00:35:20,184 --> 00:35:22,052 You know, for something that's so big and powerful, 672 00:35:22,153 --> 00:35:23,320 it's very gentle sounding. 673 00:35:24,922 --> 00:35:27,991 It really, you know, disguises the fact 674 00:35:28,092 --> 00:35:29,392 that it's incredibly destructive and would 675 00:35:29,494 --> 00:35:30,293 kill me in an instant. 676 00:35:32,597 --> 00:35:34,564 NARRATOR: These strange sounds could 677 00:35:34,665 --> 00:35:37,767 actually reveal what gives the solar wind 678 00:35:37,869 --> 00:35:39,636 its destructive power. 679 00:35:39,770 --> 00:35:42,739 Fluctuations in the Sun's magnetic field 680 00:35:42,840 --> 00:35:45,342 generate waves that roll through the particles 681 00:35:45,443 --> 00:35:46,276 of the solar wind. 682 00:35:48,613 --> 00:35:51,248 These acoustic waves transport particles with them 683 00:35:51,349 --> 00:35:52,482 that give them energy. 684 00:35:52,583 --> 00:35:53,984 Think about a surfer actually going 685 00:35:54,085 --> 00:35:55,552 down the surface of a wave, going 686 00:35:55,653 --> 00:35:57,120 faster and faster all the time. 687 00:35:58,956 --> 00:36:01,958 NARRATOR: These waves could be what accelerates the particles 688 00:36:02,059 --> 00:36:07,964 in the solar wind from 0 to 720,000 miles-an-hour, 689 00:36:08,065 --> 00:36:10,300 giving them the momentum they need to reach 690 00:36:10,401 --> 00:36:11,902 far into the solar system. 691 00:36:13,905 --> 00:36:17,007 The solar winds travel just incredible distances. 692 00:36:17,108 --> 00:36:19,676 You know, they go past the Earth, past Jupiter. 693 00:36:19,777 --> 00:36:22,212 They've even been seen past Pluto. 694 00:36:24,348 --> 00:36:26,449 MICHELLE THALLER: It really does pack a wallop, even all the way 695 00:36:26,551 --> 00:36:27,751 at the edge of our solar system. 696 00:36:29,253 --> 00:36:31,588 One of the things that really surprised me is that Pluto... 697 00:36:31,689 --> 00:36:33,990 There are bits of its atmosphere being blasted off 698 00:36:34,091 --> 00:36:35,825 by the solar wind all the time. 699 00:36:35,927 --> 00:36:38,662 Tons of atmosphere a day are being lost from Pluto. 700 00:36:40,097 --> 00:36:41,765 NARRATOR: The solar wind is powerful enough 701 00:36:41,866 --> 00:36:47,571 to blast past the planets to the very edges of our solar system. 702 00:36:50,174 --> 00:36:53,944 When we sent members of the solar fleet to investigate, 703 00:36:54,045 --> 00:36:58,048 we witnessed a battle between the Sun and interstellar space. 704 00:37:00,051 --> 00:37:03,453 A battle that could decide the fate of our planet. 705 00:37:06,524 --> 00:37:06,556 [explosion] 706 00:37:15,366 --> 00:37:18,735 The Sun blasts the solar system with a storm of particles. 707 00:37:20,271 --> 00:37:21,004 The solar wind. 708 00:37:22,640 --> 00:37:24,207 But how far does that wind reach? 709 00:37:26,644 --> 00:37:29,512 For 40 years, the oldest members of the solar fleet 710 00:37:29,614 --> 00:37:31,648 have been on a long-range reconnaissance 711 00:37:31,749 --> 00:37:33,316 mission to find out. 712 00:37:35,586 --> 00:37:38,355 The Voyager program, it was a wonderful idea. 713 00:37:38,456 --> 00:37:41,491 A grand tour of the outer solar system in the latter part 714 00:37:41,592 --> 00:37:43,193 of the 1970s. 715 00:37:43,294 --> 00:37:45,929 In fact, both Voyagers have traveled so far now 716 00:37:46,030 --> 00:37:48,131 that they've effectively reached the outer edges 717 00:37:48,232 --> 00:37:50,233 of our solar system, that boundary 718 00:37:50,334 --> 00:37:53,036 zone where the Sun's influence wanes and the stars take over. 719 00:37:55,072 --> 00:37:57,741 NARRATOR: Over 11 billion miles away, 720 00:37:57,842 --> 00:38:01,278 the Voyager probes cross over into interstellar space. 721 00:38:03,114 --> 00:38:05,248 But have they reached the edge of the solar wind? 722 00:38:06,617 --> 00:38:10,153 Voyager 2, it was able to sample the environment 723 00:38:10,254 --> 00:38:13,156 around it and found the usual mix of solar wind particles 724 00:38:13,257 --> 00:38:16,626 give way to a different flavor of particles 725 00:38:16,727 --> 00:38:20,697 with different energies, the general interstellar 726 00:38:20,798 --> 00:38:24,000 mix of particles that are just hanging out in our galaxy. 727 00:38:25,403 --> 00:38:27,003 The solar wind actually smashes 728 00:38:27,104 --> 00:38:31,274 into and shocks up against the gas of the interstellar medium. 729 00:38:31,375 --> 00:38:33,410 We discovered the edge of our solar system. 730 00:38:33,511 --> 00:38:35,645 And it was much more dramatic, much more active 731 00:38:35,746 --> 00:38:36,880 than we anticipated. 732 00:38:39,383 --> 00:38:41,918 NARRATOR: Interstellar space is violent 733 00:38:42,019 --> 00:38:44,888 and dangerous, teeming with lethal radiation. 734 00:38:47,591 --> 00:38:51,594 Supernova blasts and colliding neutron stars 735 00:38:51,696 --> 00:38:54,831 send cosmic rays across the galaxy straight 736 00:38:54,932 --> 00:38:56,032 toward our solar system. 737 00:38:58,769 --> 00:39:01,271 But these deadly threats are stopped in their tracks. 738 00:39:03,941 --> 00:39:05,375 MICHELLE THALLER: We really do live inside kind 739 00:39:05,476 --> 00:39:08,745 of a protective bubble that's being blown by the solar wind. 740 00:39:08,846 --> 00:39:11,281 You see, as the solar wind moves out into our solar system, 741 00:39:11,382 --> 00:39:14,017 it carries with it the Sun's magnetic field. 742 00:39:14,118 --> 00:39:16,319 That magnetic field protects us from the highest 743 00:39:16,420 --> 00:39:19,622 energy particles the universe can come up with... cosmic rays. 744 00:39:19,724 --> 00:39:22,525 In some cases, a single proton can have as much energy 745 00:39:22,626 --> 00:39:24,060 as a 100 mile-an-hour fastball. 746 00:39:25,696 --> 00:39:27,664 NARRATOR: Without this protective bubble, called 747 00:39:27,765 --> 00:39:32,402 the heliosphere, cosmic protons would smash through your cells, 748 00:39:32,503 --> 00:39:33,470 damaging your DNA. 749 00:39:35,172 --> 00:39:38,508 Ironically, the solar wind is deadly. 750 00:39:38,609 --> 00:39:40,643 But without it, we wouldn't be here. 751 00:39:42,880 --> 00:39:44,447 PHIL PLAIT: Like we saw with Mars, 752 00:39:44,548 --> 00:39:48,585 the solar wind has the ability to wipe out life on Earth. 753 00:39:48,686 --> 00:39:52,122 But out there in the furthest reaches of our solar system, 754 00:39:52,223 --> 00:39:54,524 it's defending life on Earth. 755 00:39:54,625 --> 00:39:56,593 So in a way, it's a giver of life. 756 00:39:56,694 --> 00:39:57,560 And it takes life. 757 00:39:57,661 --> 00:39:58,561 A yin and a yang. 758 00:40:01,766 --> 00:40:04,401 NARRATOR: And now for the first time, 759 00:40:04,502 --> 00:40:07,971 the Voyager probes have looked back at the heliosphere 760 00:40:08,072 --> 00:40:12,976 from the outside, revealing what our solar system looks 761 00:40:13,077 --> 00:40:14,944 like as it moves through space. 762 00:40:17,748 --> 00:40:20,316 Something that we lose sight of sitting here on Earth, 763 00:40:20,418 --> 00:40:23,286 watching the Sun go around, watching the planets go around, 764 00:40:23,354 --> 00:40:27,424 is that the Sun itself is actually hurtling through space 765 00:40:27,525 --> 00:40:29,826 really, really fast on an orbit around the center 766 00:40:29,927 --> 00:40:30,627 of our galaxy. 767 00:40:32,363 --> 00:40:34,631 If our Sun were perfectly stationary, 768 00:40:34,732 --> 00:40:38,101 then the heliosphere would be a perfect sphere. 769 00:40:38,202 --> 00:40:41,204 But because it's moving, it's plowing 770 00:40:41,305 --> 00:40:43,640 through that interstellar medium. 771 00:40:43,774 --> 00:40:45,875 And so that makes one end shorter 772 00:40:45,976 --> 00:40:47,777 and the other end longer. 773 00:40:47,912 --> 00:40:51,548 And new research is showing it's even more complicated than that 774 00:40:51,649 --> 00:40:54,150 where we might have like a double tail, 775 00:40:54,251 --> 00:40:57,787 almost like a buttery croissant surrounding the Sun. 776 00:41:00,458 --> 00:41:03,593 NARRATOR: Our Sun shapes our world 777 00:41:03,694 --> 00:41:06,896 and protects us from the dangers of interstellar space. 778 00:41:09,667 --> 00:41:12,302 It's the engine that drives the entire solar system. 779 00:41:15,039 --> 00:41:19,275 And now, for the first time, our fleet of solar spacecraft 780 00:41:19,376 --> 00:41:21,344 shows us how it works. 781 00:41:22,847 --> 00:41:24,547 We're pretty familiar with the Sun, right? 782 00:41:24,648 --> 00:41:26,082 You see it all the time during the day. 783 00:41:26,183 --> 00:41:26,950 Lights up the Earth. 784 00:41:27,051 --> 00:41:28,251 Provides us with heat. 785 00:41:28,352 --> 00:41:30,954 But observing it with all these other satellites, all 786 00:41:31,055 --> 00:41:33,790 these observatories, has shown us a side of the Sun 787 00:41:33,891 --> 00:41:35,191 that we knew nothing about. 788 00:41:37,261 --> 00:41:39,462 JESSIE CHRISTIANSEN: We have this whole fleet of spacecraft 789 00:41:39,563 --> 00:41:41,931 orbiting the Sun taking observations in all 790 00:41:42,032 --> 00:41:43,166 of these different wavelengths. 791 00:41:43,267 --> 00:41:45,902 X-ray, ultraviolet, optical, infrared. 792 00:41:46,003 --> 00:41:48,705 They tell us about the functioning of the Sun 793 00:41:48,806 --> 00:41:51,474 from its outer atmosphere down to its deep core 794 00:41:51,575 --> 00:41:54,978 and give us a window into its functions and its evolution. 795 00:41:56,914 --> 00:41:59,883 Put them all together, and we finally have an understanding 796 00:41:59,984 --> 00:42:02,552 of our source of life itself.