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00:00There's a violent star at the center of our solar system.
00:06The immense power, the roiling, boiling surface, the massive plumes, it's ridiculous.
00:15And our planet is at its mercy.
00:18There are explosions and big, giant eruptions of plasma that head straight to Earth.
00:26We have to understand these better to protect ourselves.
00:30The sun is a churning cauldron of nuclear reactions.
00:35Revealing its inner workings was once mission impossible, but not anymore.
00:42We've recruited this network of spies, if you will.
00:45We've built a fleet of spacecraft that monitor the sun 24 hours a day.
00:51With the sun under close surveillance, we just might have what it takes to defend our planet.
00:58NASA Jet Propulsion Laboratory, California Institute of Technology
01:13September 6, 2017
01:17A flash of ultraviolet and X-ray light erupts from the sun,
01:23sending a burst of radiation toward Earth.
01:27We call it a solar flare.
01:30Flares are huge explosions on the surface of the sun,
01:34throwing light out into the solar system and absolutely baking anything in its path.
01:39These are really powerful events erupting from the sun, and we are fundamentally in the line of fire.
01:46The flare is so intense, it causes radio blackouts across the side of the Earth facing the sun.
01:55And the timing could not have been worse.
02:00The problem was, at this time, there were hurricanes in the Atlantic bearing down on the Caribbean,
02:06and there were people trying to get in there and rescue folks.
02:09Radio communication between disaster relief teams goes down for most of the day.
02:16Space weather and Earth weather combine to create chaos.
02:24It's not just an academic exercise.
02:27Your very lifestyle depends on understanding how the sun behaves.
02:32We need to be able to predict what the sun is going to do next.
02:35And in order to do that, we need to have eyes on the sun.
02:38As many eyes as we can get.
02:40Three, two, one.
02:44That's why NASA has put together an elite unit.
02:48We have ignition and we have liftoff.
02:51Liftoff and liftoff on an international mission of solar physics.
02:56Liftoff and liftoff on an international mission of solar physics.
03:01A fleet of daring spacecraft.
03:04We humans have come a long way.
03:06If you go back a few thousand years, people were worshipping the sun.
03:10And today, we've built a fleet of spacecraft that monitor the sun 24 hours a day,
03:16observing it from every angle, predicting what it's going to do next.
03:21That's nuts.
03:24Leading the pack is the Solar Dynamics Observatory, or SDO.
03:30It keeps a telescopic eye on flares blasting out from the sun's surface.
03:3624 hours a day, the SDO probe is on the lookout.
03:40It's constantly vigilant.
03:43It looks at the sun at a lot of different wavelengths in exquisite detail
03:47so that we can see exactly what sort of high-energy events are happening on the sun.
03:53The record for the longest service goes to SOHO,
03:57our sentinel monitoring the sun and its faint outer atmosphere.
04:03The Solar and Heliospheric Observatory, or SOHO, is the old hand at studying the sun.
04:08It's been up there for 25 years, observing not just the sun itself, but the environment around it.
04:15Instead of looking directly at it, it actually blocks out most of the light
04:19so that we can see all these beautiful structures that surround the sun.
04:26And then there's the new recruit, the Parker Solar Probe,
04:31our scout going deep behind enemy lines.
04:35The Parker Solar Probe is going to give us the closest look at the sun
04:40that we have ever had in the history of humanity.
04:44We're flying so close to the sun, we're flying through the gases of its atmosphere.
04:5029 other craft make up the fleet, each with their own role to play.
04:56This fleet of spacecraft that we have, the overall mission is to observe the sun,
05:01scientifically, learn about its behavior, but also, importantly,
05:05to learn about the effects that it has on Earth.
05:11Our lookout probe, the Solar Dynamics Observatory, or SDO, spots something hellish.
05:21Today's forecast for the sun is predicted to be 10,000 degrees Fahrenheit
05:25with winds of up to 600 miles per second,
05:29and a pretty decent chance of rain.
05:32You don't want to be in this rainstorm because your umbrella isn't going to help you.
05:37Solar rain isn't water, it's plasma, hot plasma.
05:42Rather than a solid, liquid, or gas,
05:46the entire sun is made up of a strange fourth state of matter,
05:51plasma.
05:55Now, we're familiar with three forms of matter, you know, solid, holds its shape, liquid, flows.
06:00A plasma is very much like a gas, except the atoms in the gas
06:04have had their electrons stripped off.
06:08Rip those electrons off, it's not an atom anymore, it's an ion,
06:12and a free electron, and we call that state plasma.
06:17Plasma may sound weird,
06:20but we find it closer to home than you might think.
06:23There is plasma on Earth, it just doesn't last very long.
06:26So, for example, when you see a lightning strike,
06:29the glow from that is coming from ionized air, plasma.
06:35Plasma is just simply gas that's very hot.
06:39So hot it's lost some of its electrons and become electrically charged.
06:43And the wonderful thing about plasma is that once it has that electric charge,
06:47you can direct it with a magnetic field.
06:50And the sun has the most powerful magnetic field in the solar system.
06:56It twists and flows through the entire star.
07:00The sun's magnetic field is incredibly complicated.
07:03There are lots of loops of magnetic lines coming out of the sun's surface.
07:10As you go above the surface,
07:12the magnetic field begins to control where the gas can go,
07:16and you get these beautiful loops and other structures above the sun
07:20that are just showing you where the magnetic field is.
07:23The SDO spacecraft's jaw-dropping videos of rain on the sun
07:28show plasma flowing along huge, looping magnetic field lines
07:33that have punched through the sun's surface.
07:36Because the surface of the sun is a plasma,
07:38and these loops of magnetic fields are coming out of it,
07:41it draws that plasma up, which then cools and rains down as a plasma rain.
07:46Tracking these loops of magnetic field and plasma could help explain solar flares.
07:54And it could give us some warning.
07:58September, 2017.
08:02Minutes before the devastating mid-hurricane radio blackout,
08:07our Solar Lookout spotted an explosion on the surface of the Sun.
08:11Suddenly, you have this tremendous flow of energy and an explosive release of it,
08:15and we call this a solar flare.
08:17This is SDO's specialty of observation.
08:21The craft tracked the magnetic loops above the sun's surface.
08:27They were highly unstable.
08:31SDO takes very detailed pictures of where the flares are.
08:37SDO takes very detailed pictures of where the flows are.
08:41You can actually see gas flowing from one place.
08:44You can see the magnetic loops.
08:49These magnetic flux loops are kind of like wires carrying electricity.
08:53When they're on their own, they're fine.
08:55But if they get too close, they can connect and short-circuit,
08:58and then you get a tremendous release of energy.
09:00The Ghostbusters were really on to something.
09:02Don't cross the streams.
09:06The contact between magnetic loops
09:09released an epic explosion of high-energy light.
09:14This radiation altered our planet's atmosphere.
09:20Radio waves jammed, causing blackouts at the worst possible moment.
09:24Solar flares are happening on the sun 90 million miles away.
09:28Who cares, right?
09:29Well, think of it this way.
09:30A really good solar flare could be the equivalent of,
09:33oh, say, 10 million hydrogen bombs going off.
09:37How's that sound?
09:38Solar flares happen a lot, and they do affect us.
09:42They have affected us in the past,
09:44and they will again in the future.
09:47But the sun's twisting magnetic fields don't stop them.
09:52But the sun's twisting magnetic fields
09:54do more than just disrupt our communications.
09:58And when we see flares, we've got to keep an eye out on those.
10:01But sometimes there's something even bigger.
10:06The sun launches huge clouds of plasma across the solar system.
10:12All of that material can come to the Earth
10:14and really mess things up here,
10:16blow out our power grid, destroy our satellites,
10:19and even physically harm our astronauts in orbit.
10:23Can the solar fleet safeguard Earth?
10:33November 5, 2018.
10:35An explosive cloud of plasma hits the Parker Solar Probe
10:40as it orbits just 15 million miles from the sun.
10:46We have this fleet of spacecraft out there
10:48viewing the sun, and they're also under attack by the sun.
10:53There are explosions coming from its surface.
10:56It's not just light, but explosions of hot plasma.
11:00And the Parker Solar Probe got blasted, and yet it survived.
11:07A huge blast of high-energy charged particles
11:10launches into the solar system at millions of miles an hour.
11:15A coronal mass ejection.
11:23But our Solar Scout is prepared for the onslaught.
11:26The Parker Solar Probe gets very close to the sun,
11:29and it has a heat shield to protect it.
11:31But if it gets hit by a coronal mass ejection,
11:34it has to be protected against that as well.
11:36And so it's been radiation-hardened to survive such an impact.
11:41Could these blasts pose a danger to our planet?
11:46A coronal mass ejection accelerates subatomic particles,
11:50and it's not a little bit of particles.
11:52It could be up to a billion tons of them
11:55screaming across the solar system at high speed.
11:58And this is something we need to take very seriously.
12:03To understand these dangerous blasts of plasma,
12:07we have to look at their source.
12:11An area around the sun known as the corona.
12:15The sun's corona is kind of like its atmosphere.
12:18You can think of the sun itself as being a ball of gas,
12:21and then outside of that is this ethereally thin gas
12:24stretching out for millions of miles.
12:28The corona is a difficult thing to study
12:31because the surface of the sun is so bright it blocks our view.
12:36We can only see the corona during a total solar eclipse,
12:41when the moon blocks the sun's bright glare.
12:48And in 2017, we caught a break.
12:53The total solar eclipse in August of 2017
12:56was my third total solar eclipse,
12:58and I'll never get tired of seeing them.
13:01It's a magic, amazing event.
13:04Over the course of the day,
13:05the moon slowly slipped in front of the sun,
13:07and we got more and more excited.
13:09And that moment of totality when the moon blocked the sun
13:12and we saw the corona stretching out,
13:15that was life-changing.
13:17That was one of the most beautiful things
13:20I have ever seen in my life.
13:24Seeing a total solar eclipse is surreal.
13:27You see them in movies, you see them on television,
13:29but to see one in real life
13:31and to see the corona emerge in the darkness
13:34once the sun's disk is covered by the moon,
13:37it's almost like being in a movie.
13:40The solar corona is made up of the same plasma
13:43as the surface of the sun,
13:46except it's even hotter
13:49and reaches far out into space.
13:53It's very tenuous. It's very faint, though.
13:55And so from here on the Earth,
13:57there's not a ghost of a chance of seeing it in the daytime sky.
14:00You look up, you're blinded by the light of the sun.
14:02It's trillions of times more intense.
14:06You can only see it during a solar eclipse,
14:09when the moon blocks the bright surface of the sun
14:12and allows that fainter light to be seen.
14:16The problem is the moment of totality,
14:19when the corona reveals itself,
14:21only lasts for a few minutes.
14:26Astronomers, though, we're impatient.
14:28We don't want to have to wait for a total solar eclipse,
14:30which only happens once or twice a year.
14:32So we figured out a way to make an artificial one.
14:35And it's really simple.
14:39One member of the solar fleet has it covered.
14:42Our solar sentinel, SOHO,
14:45creates its own eclipse
14:48by obscuring the blinding sun
14:50with a circular plate in front of the probe's camera.
14:54Sometimes the best solution is the simplest solution.
14:57You know, instead of trying to make a sensor
15:00that could actually see the full dynamic range of the sun's light,
15:04you know, why not just block out the light that we don't need?
15:09In July 2012,
15:11SOHO spotted a huge chunk of the corona
15:14blasting off into the solar system.
15:19Seconds earlier, another probe,
15:21monitoring the solar surface,
15:23spotted a bright flare.
15:27Were these events connected?
15:30If a flare goes off, it can disrupt those loops.
15:33And if you get the right kind of disruption,
15:36the whole thing can just blow open.
15:38And then you have a tremendous amount of
15:41billions of tons of hydrogen
15:43blown off into interplanetary space.
15:46And that's a coronal mass ejection.
15:51Coronal mass ejections are solar flares on steroids.
15:56If a solar flare was a firecracker,
15:58a coronal mass ejection is more like an atom bomb.
16:08And if a coronal mass ejection comes our way,
16:11it hits hard.
16:13The first thing it does is it compresses Earth's magnetic field,
16:17and then it wraps around the Earth,
16:20and this causes the magnetic field itself to rearrange,
16:23reconnect, and streams of particles
16:25travel down those magnetic fields toward our poles
16:28and impact the atmosphere.
16:30Our shields are up, but they are able to penetrate our shields,
16:34our shield being our own magnetic field.
16:37Once they breach our defenses,
16:39the particles of a coronal mass ejection can wreak havoc.
16:46In August of 1972, tensions were running high in Vietnam.
16:54Two dozen sea mines detonated at the same time
16:57when their magnetic sensors were tripped.
16:59A satellite was lost because of the electromagnetic pulse
17:02that ripped through it.
17:04And an Air Force sensor detected what looked like
17:07a nuclear explosion somewhere here on the planet.
17:10Fortunately, scientists quickly found the real culprit.
17:16A coronal mass ejection had ripped through the Earth's magnetic field
17:20and triggered magnetic sensors.
17:24The crisis soon de-escalated.
17:28The sun is an immense ball of plasma 860,000 miles across.
17:33We are not going to be able to stop it
17:35from doing whatever it wants to do.
17:37What we can do is learn to predict what's going to happen,
17:41so we're doing that now.
17:43Our new fleet of solar observers are our first line of defense.
17:50The sun is a little over 90 million miles from Earth.
17:53It takes light a little over eight minutes
17:55to get from there to here.
17:57As rapidly as a coronal mass ejection is traveling,
18:00it still takes a few days to get here.
18:03We can watch the sun to see, is there going to be an event?
18:06Or is an event starting?
18:08And these satellites can then tell us,
18:10hey, you better be careful.
18:12You might need to batten down the hatches on Earth.
18:17But there may be an earlier clue the fleet can watch out for.
18:21Vast, dark regions of the solar system
18:24could be a threat to the planet's future.
18:28But there may be an earlier clue the fleet can watch out for.
18:32Vast, dark regions moving across the solar surface,
18:36called sunspots.
18:39We know that this is the wind-up before the release.
18:42This thing is getting ready to blow.
18:52In March of 1989,
18:55a solar eruption caused blackouts across Canada
19:00and malfunctions on board the space shuttle.
19:04We've been seeing some erratic pressure signatures out of Tank 3,
19:08as well as some manifold pressure spikes in that system.
19:12Eleven years later, the sun emitted a flare that was so powerful,
19:16it blinded the solar fleet's sensors.
19:21Eleven years after that,
19:23the Earth had a near-miss with the most powerful
19:26coronal mass ejection ever recorded.
19:32The sun has a very predictable,
19:34but actually quite mysterious cycle of activity.
19:36It gets very, very active every 11 years,
19:39and then it settles back down to more of a peaceful existence.
19:43This 11-year cycle has astronomers scratching their heads.
19:48One thing we do know is that violent solar events
19:51seem to be preceded by dark patches on the solar surface.
19:57Sunspots.
19:59Sunspots are large areas on the surface of the sun,
20:02much bigger than the Earth,
20:04that are caused by incredibly strong magnetic fields
20:08disrupting the flow of plasma.
20:11And every 11 years, these dark spots grow in number,
20:16like clouds gathering before a storm.
20:21When you start seeing more and more sunspots,
20:23there's an expectation that you're going to see
20:25more intense and more frequent solar flares.
20:31But what drives this 11-year cycle?
20:35It's kind of ironic that one of the most predictable things
20:37about the sun is also the most mysterious.
20:41We've been puzzling over the sunspot cycle for generations,
20:46and now finally we have spacecraft headed to the sun
20:50to try to give us some answers.
20:53The SOHO, SDO, and STEREO spacecraft monitor the sun's atmosphere
20:58using ultraviolet telescopes.
21:02They spot flashes of high-energy, ultraviolet light moving across the sun.
21:11These waves of light could be connected to the cycle of sunspots
21:16and to the sun's outbursts,
21:19because everything we see on the sun's surface
21:23is controlled by violent processes deep in its interior.
21:31The sun is a very simple onion.
21:35At the very, very center is the core where the nuclear fusion happens.
21:39A layer surrounding that is known as the radiative zone,
21:43where most of the energy gets pushed out through radiation.
21:47Then surrounding that is something called the convective zone,
21:51where there's great plumes and chains of plasma moving up and down, up and down.
21:58But unlike an onion, the layers spin.
22:04There are currents inside the sun that we don't see from the surface.
22:08Layers of the sun deep down inside are rotating at different rates
22:11than the layers above.
22:14So it turns out the inner part of the sun is rotating at maybe three times
22:18more rapidly than the outer part of the sun.
22:22We also can see on the outer part of the sun that the equator is rotating
22:25more rapidly than the pole.
22:30These layers of plasma grinding against each other
22:33generate the sun's enormously powerful magnetic field
22:38and give rise to sunspots, plasma loops, and solar flares.
22:44This differential rotation takes the field and starts twisting it around the sun.
22:50So as the magnetic field gets too twisted, it starts knotting up
22:54and these knots start bubbling up to the surface,
22:56and that's what we're seeing actually with the sunspots.
23:00And that's why you see all these wonderful loops and prominences coming off the sun.
23:04Once the magnetic fields start twisting and interacting,
23:07they can direct the plasma into vast rivers and loops
23:10both above and below the surface of the sun.
23:16Why these events flare up every 11 years is a mystery.
23:22But now, new observations from the solar fleet could provide a clue
23:26about what triggers the solar cycle.
23:30Giant, moving magnetic fields beneath the sun's surface.
23:37We think that the ultraviolet light flickers are telling us where the magnetic field is.
23:44In the course of the 11-year cycle, the sun's magnetic fields
23:47begin to move down from the poles, closer and closer to the equator.
23:52As the magnetic field lines move through the star,
23:55they carry huge amounts of plasma with them.
24:00The magnetic field lines act like shepherds for the plasma underneath the surface,
24:06and they push plasma down to the equator of the sun.
24:11The magnetic fields trap enormous amounts of plasma, like water behind a dam,
24:18until eventually the floodgates open and the plasma comes rushing out.
24:24When the magnetic fields meet, they cancel each other out
24:27and release the plasma, which goes as a tsunami wave back to the poles.
24:34When that plasma rebounds from the equator and hits the magnetic field
24:37coming down from the poles at the mid-latitudes,
24:39you get a huge burst of magnetic activity.
24:43Magnetic activity that triggers sunspots and loops also explains the 11-year cycle.
24:54We think that this relationship between the magnetic fields,
24:57the ultraviolet flickers, and the plasma drives the 11-year cycle.
25:03We think this is what's actually doing the work.
25:07The solar cycle has wound down for now.
25:11But once the next plasma tsunami rushes through the sun,
25:15our star will kickstart into action again.
25:20Over the next few years, we're going to start to see more sunspots,
25:23more activity, more flares, more ejections,
25:27and more space weather that we have to deal with.
25:31Our fleet of solar spies is poised and ready.
25:39But flares and coronal mass ejections are not the only solar attacks
25:43we have to shield ourselves against.
25:47There's a strange, invisible force flowing through the entire solar system.
25:53There is this great wind of high-energy particles from the sun,
25:55a million-mile-an-hour wind.
25:59And it can be deadly.
26:09In November 2019, the solar fleet watched as Mercury sailed across the sun.
26:17Mercury is the closest planet to our sun in our solar system,
26:21so it's on the front line, receiving all of this radiation,
26:24an incredible amount of energy, and it's such a tiny planet.
26:29Temperatures on the innermost planet's surface reach 800 degrees Fahrenheit.
26:35But scientists discovered something unexpected on Mercury.
26:40Frozen pools of water, hidden in its craters.
26:46It's one of the last places in the solar system you might expect to find ice on Mercury,
26:50one of the hottest planets in the solar system.
26:52Despite the overall really high temperatures across the whole planet,
26:56there are regions, typically deep within craters, that are permanently shadowed.
27:01So there's never direct sunlight on those regions of Mercury,
27:05and you can keep things as cold as ice in those craters.
27:09But where did the ice come from?
27:12When we first saw that there was ice on Mercury,
27:15we thought something must have brought it there,
27:17something like a comet, which is made out of ice.
27:21But there's a new idea that maybe the materials that make this ice
27:26are actually coming from the sun.
27:31The sun creating ice sounds strange,
27:35but recent research shows it's not as crazy as it seems.
27:40We often think of space as being empty,
27:42but in fact, we are bathed in a wind, a million-mile-an-hour wind
27:46of high-energy particles from the sun all the time, the solar wind.
27:52A stream of subatomic particles called protons
27:55constantly flow out from the sun in all directions,
28:01bombarding the planets of our solar system.
28:07The solar wind is so strong when it hits Mercury
28:10that it can break down some of the minerals and rocks on its surface
28:13into their constituent parts.
28:15And those parts, especially if they have oxygen in them,
28:18can go to reform and form water,
28:21which, if it forms in the right place, can then stick around.
28:27Protons in the solar wind combine with oxygen to form water molecules.
28:32They condense and freeze in craters, which never see sunlight.
28:36So, even on the sun's closest neighbor, ice builds up.
28:42But the solar wind doesn't stop at Mercury.
28:48The solar wind has a tremendous impact on the worlds of our solar system.
28:53We think it's responsible for the planet Venus becoming this hellhole of heat.
28:59Up until as recently as 700 million years ago,
29:02Venus was a lush water world with conditions suitable for life.
29:08But the solar wind blasted away the water vapor and oxygen from Venus' atmosphere,
29:13leaving carbon dioxide to dominate,
29:17trapping the sun's heat and causing surface temperatures to skyrocket.
29:23Mars was once habitable, too.
29:27But the solar wind quickly took care of that as well.
29:32We believe that billions of years ago, Mars had an atmosphere and had oceans and rivers.
29:38It looked a lot like Earth. It was gorgeous.
29:40But that solar wind stripped away the Martian atmosphere
29:45and turned it into the barren wasteland that it is today.
29:48And Earth is in the line of fire, too.
29:51It's bombarded every day with solar wind particles.
29:57So, how has life survived?
30:00One of the things we really take for granted is how well-protected we are here on the Earth.
30:04The atmosphere absorbs a lot of harmful things from space and from the sun as well,
30:08but also our magnetic field, deflects.
30:10So, we have a lot of things that we don't have.
30:12The atmosphere absorbs a lot of harmful things from space and from the sun as well,
30:16but also our magnetic field, deflects.
30:18The solar wind around us, and we still have an atmosphere.
30:23And when the charged particles come from the sun,
30:25the magnetic field lines trap those charged particles and redirect them to the poles of the planet.
30:31The physical effect, the direct physical effect of getting bombarded by these particles,
30:35they can generate the aurora borealis, the northern lights.
30:38And these are spectacular and beautiful.
30:42Auroras are beautiful,
30:45but they're also the front line in the battle between Earth and the solar wind.
30:51Without our protective shield, we'd suffer the same fate as Venus or Mars.
30:57But there is a mystery surrounding the solar wind.
31:01One of the things we know about the solar wind is that it is hugely energetic,
31:05a million miles an hour.
31:06What gives it that energy?
31:09Astronomers think the source of the solar wind lies in the inner corona,
31:16the atmosphere of the sun revealed by our solar sentinel, SOHO.
31:22SOHO's data shows that near the sun's surface, the wind speed is close to zero.
31:29But by the time the wind gets to the outer corona, it accelerates
31:34to 720,000 miles an hour.
31:38Something happens mysterious between the surface of the sun and the corona
31:42that gives a punch to the solar wind.
31:45To investigate, we need to visit the corona.
31:50So NASA sent a scout on a daring mission behind enemy lines.
31:57The Parker Solar Probe, that's a daredevil.
32:00This is designed to dive bomb the sun.
32:09The sun exerts a hostile influence on the planets of our solar system.
32:17The solar wind.
32:19It's fast, it's lethal.
32:22But we don't know how it works.
32:25We have spacecraft between us and the sun that can actually see
32:28what's coming toward us and how it will impact us.
32:30But what scientists have never been able to explain is
32:33what actually accelerates the wind away from us.
32:36What actually accelerates the wind away from the sun?
32:39This has been one of the biggest mysteries of the sun so far.
32:44For decades, we had no way of solving it.
32:48Until now.
32:51There really are some of these wonderful moments when you're a scientist.
32:54And I was actually at the launch of the Parker Solar Probe,
32:57standing right next to Dr. Eugene Parker, who the probe was named after.
33:01Liftoff of the Parker Solar Probe.
33:03Long ago, he had proposed the sun probably had a wind of particles
33:07that affected the Earth.
33:08And people basically laughed at him.
33:10But he was proven right over time.
33:12And as that giant delta rocket slowly went up from the pad,
33:15he and I both got to be bathed in that light and smile.
33:21There has been no spacecraft ever in human history
33:25to fly through the corona, the very atmosphere of the sun.
33:29It didn't work out well for Icarus, and we hope it works out well for Parker.
33:33The thing about going near the sun is the closer you go to it,
33:37the closer your temperature gets to its surface temperature.
33:41And its surface temperature is 6,000 degrees, which vaporizes metal easily.
33:48Surviving close to the sun is a big ask.
33:52But reaching the sun? That's an even bigger challenge.
33:55It's very hot. It tends to melt your spacecraft.
33:58That's the obvious problem.
34:00A less obvious problem is it's just hard to get there.
34:03This is something, I think, that is very hard for most people to grasp.
34:07There have been suggestions of, you know,
34:09let's send all our nuclear waste into the sun or our trash or whatever.
34:13And it turns out to be very difficult to drop anything into the sun.
34:18The reason is the Earth is circling around the sun
34:22at 67,000 miles an hour.
34:25That's good, because that means we don't drop into the sun.
34:28We stay at the same distance.
34:30But if you do want to drop into the sun,
34:32you have to lose that velocity, and that's a lot of velocity.
34:37To lose speed, the Parker Solar Probe swings by Venus,
34:42performing a gravitational slingshot in reverse.
34:46Now, usually, a gravitational slingshot gives us more velocity.
34:50So if we're flying out to Pluto, for example,
34:52we might whip the spacecraft around the planet Jupiter.
34:55It actually takes the spacecraft and gravitationally slingshots it forward,
34:59making it go faster.
35:01The thing that we have to do with Parker Solar Probe is the opposite.
35:04We're going to use a gravitational slingshot,
35:06but not to speed it up, to slow it down.
35:09Parker's gravitational maneuvers are designed
35:13Parker's gravitational maneuvers send the craft
35:16on a trajectory inside the sun's extended corona,
35:22closer to the sun than any spacecraft before it.
35:27This probe actually dives really deep toward the sun,
35:31so it's actually going through some of this coronal material
35:35and can actually observe it directly in a way that other probes can't.
35:39Using its extreme ultraviolet telescope,
35:42Parker spots vast, dark regions below.
35:48There's really interesting regions called coronal holes,
35:51where you can see literally deeper into the sun.
35:55Coronal holes are areas of the sun's corona
35:58where the atmosphere is cooler and less dense.
36:04And when the probe passes over a hole,
36:07in the corona, it gets more.
36:10It gets a bigger blast of the solar wind.
36:13These coronal holes appear to be the source of the solar wind.
36:18We think it's through these holes that the solar wind is able to escape the sun.
36:23The big question is, how does the solar wind actually accelerate away from the sun?
36:29It seems to defy logic.
36:33You would think that as something leaves the source,
36:36it would probably start to slow down, or at least stay the same speed.
36:39But this doesn't. It gets faster.
36:42Something is accelerating the solar wind.
36:45It gets faster and hotter as it moves away from the surface of the sun,
36:48and the mechanism is a mystery.
36:51To solve the mystery, our Solar Scout dives close to the sun,
36:57not to see what's going on, but to listen.
37:07That sounded spooky.
37:10That sounded really spooky.
37:12You know, for something that's so big and powerful, it's very gentle sounding.
37:17It really, you know, disguises the fact that it's incredibly destructive and would kill me in an instant.
37:25These strange sounds could actually reveal a secret.
37:30In an instant.
37:33These strange sounds could actually reveal what gives the solar wind its destructive power.
37:40Fluctuations in the sun's magnetic field generate waves that roll through the particles of the solar wind.
37:49These acoustic waves transport particles with them. They give them energy.
37:52Think about a surfer actually going down the surface of a wave, going faster and faster all the time.
37:58These waves could be what accelerates the particles in the solar wind from zero to 720,000 miles an hour,
38:07giving them the momentum they need to reach far into the solar system.
38:13The solar winds travel just incredible distances.
38:16You know, they go past the Earth, past Jupiter, they've even been seen past Pluto.
38:23It really does pack a wallop, even all the way at the edge of our solar system.
38:28One of the things that really surprised me is that Pluto, there are bits of its atmosphere being blasted off by the solar wind all the time.
38:35Tons of atmosphere a day are being lost from Pluto.
38:39The solar wind is powerful enough to blast past the planets,
38:44to the very edges of our solar system.
38:47But how far does that wind reach?
38:51For 40 years, the oldest members of the solar fleet have been on a long-range reconnaissance mission to find out.
39:00The Voyager program was a wonderful idea, a grand tour of the outer solar system in the latter part of the 1970s.
39:07There was a magic period of time there where one spacecraft, by doing gravity slingshots past the planets,
39:13could visit every planet.
39:15And in the process, of course, that flings the spacecraft out of the solar system at very high speeds.
39:21At this distance, our sun is just a slightly brighter point of light, set against thousands of other points of light.
39:30It is just lonely out there.
39:33In fact, both Voyagers have traveled so far now that they've effectively reached the outer edges of our solar system.
39:39That boundary zone where the sun's influence wanes and the stars take over.
39:44Over 11 billion miles away, the Voyager probes cross over into interstellar space.
39:52But have they reached the edge of the solar wind?
39:55Voyager 2 was able to sample the environment around it and found the usual mix of solar wind particles give way to a different force.
40:05The usual mix of solar wind particles give way to a different flavor of particles with different energies.
40:11The general interstellar mix of particles that are just hanging out in our galaxy.
40:19The solar wind actually smashes into and shocks up against the gas of the interstellar medium.
40:25We had discovered the edge of our solar system and it was much more dramatic, much more active than we anticipated.
40:31Interstellar space is violent and dangerous, teeming with lethal radiation.
40:41Supernova blasts and colliding neutron stars send cosmic rays across the galaxy straight toward our solar system.
40:52But these deadly threats are stopped in their tracks.
40:56We really do live inside kind of a protective bubble that's being blown by the solar wind.
41:02You see, as the solar wind moves out into our solar system, it carries with it the sun's magnetic field.
41:07That magnetic field protects us from the highest energy particles the universe can come up with, cosmic rays.
41:13In some cases, a single proton can have as much energy as a 100-mile-an-hour fastball.
41:18Without this protective bubble, called the heliosphere, cosmic protons would smash through your cells, damaging your DNA.
41:28Ironically, the solar wind is deadly, but without it, we wouldn't be here.
41:36Like we saw with Mars, the solar wind has the ability to wipe out life on Earth.
41:42But out there in the furthest reaches of our solar system, it's defending life on Earth.
41:48So in a way, it's a giver of life and it takes life, a yin and a yang.
41:55And now, for the first time, the Voyager probes have looked back at the heliosphere from the outside,
42:04revealing what our solar system looks like as it moves through space.
42:11Something that we lose sight of sitting here on Earth, watching the sun go around, watching the planets go around,
42:17is that the sun itself is actually hurtling through space really, really fast on an orbit around the center of our galaxy.
42:26If our sun were perfectly stationary, then the heliosphere would be a perfect sphere.
42:32But because it's moving, it's plowing through that interstellar medium.
42:37And so that makes one end shorter and the other end longer.
42:41And new research is showing it's even more complicated than that,
42:45where we might have like a double tail, almost like a buttery croissant surrounding the sun.
42:54Our sun shapes our world and protects us from the dangers of interstellar space.
43:03It's the engine that drives the entire solar system.
43:08And now, for the first time, our fleet of solar spacecraft shows us how it works.
43:16We're pretty familiar with the sun, right? You see it all the time during the day, lights up the Earth, provides us with heat.
43:22But observing it with all these other satellites, all these observatories, has shown us a side of the sun that we knew nothing about.
43:30We have this whole fleet of spacecraft orbiting the sun, taking observations,
43:34in all of these different wavelengths, X-ray, ultraviolet, optical, infrared.
43:39They tell us about the functioning of the sun from its outer atmosphere down to its deep core,
43:45and give us a window into its functions and its evolution.
43:50Put them all together and we finally have an understanding of our source of life itself.