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250
00:16:10,308 --> 00:16:13,435
which was the first
indication that the Sun rotated.
251
00:16:15,117 --> 00:16:17,073
Not only does the Sun rotate,
252
00:16:17,087 --> 00:16:21,709
but sunspots themselves can actually spin
like hurricanes on the solar surface.
253
00:16:22,498 --> 00:16:26,799
And when they do, their magnetic field
lines become extremely twisted.
254
00:16:28,181 --> 00:16:30,941
Twisted magnetic field lines
mean more energy
255
00:16:31,307 --> 00:16:34,707
and more energy means the
potential for huge eruptions.
256
00:16:36,013 --> 00:16:38,238
Think of a rubber band
as magnetic field line.
257
00:16:38,956 --> 00:16:43,005
If you twist it, and you twist enough
it's goin to have all that energy,
258
00:16:43,712 --> 00:16:45,759
and when you let it go
it's going to release.
259
00:16:47,519 --> 00:16:51,960
If you just take an untwisted rubber band
and release it it's not going to fly.
260
00:16:57,536 --> 00:17:00,569
When a sunspot unleashes
its magnetic energy,
261
00:17:00,710 --> 00:17:04,879
what results are the most colossal
explosions in the Solar System:
262
00:17:04,982 --> 00:17:06,550
solar flares.
263
00:17:07,233 --> 00:17:11,599
A single flare releases as much
as a billion megatons of energy.
264
00:17:12,125 --> 00:17:16,012
The combined power of a million
volcanic eruptions on Earth.
265
00:17:17,590 --> 00:17:19,009
They appear as these very...
266
00:17:19,010 --> 00:17:22,966
bright regions and they're so bright
because the temperature is so high,
267
00:17:23,238 --> 00:17:27,125
on the order of ten million degrees
and they can last for hours.
268
00:17:28,477 --> 00:17:30,385
But the energy is massive.
269
00:17:32,593 --> 00:17:34,424
The whole explosion...
270
00:17:34,565 --> 00:17:37,348
is equivalent to millions
of nuclear bombs
271
00:17:37,349 --> 00:17:39,997
leaving the surface
of the Sun all at once.
272
00:17:41,808 --> 00:17:45,566
Solar flares don't just
explode out into space.
273
00:17:45,667 --> 00:17:48,210
They also funnel high energy particles
274
00:17:48,211 --> 00:17:51,549
down to a layer of the
Sun called the cromosphere,
275
00:17:51,588 --> 00:17:54,124
where they quickly transfer their energy
276
00:17:54,125 --> 00:17:57,504
like a cue ball striking the
rack in the game of billiards.
277
00:17:58,141 --> 00:18:00,223
So you have a cue ball,
actually is like one of these
278
00:18:00,224 --> 00:18:02,525
very high energy particles
coming from the flare region.
279
00:18:04,066 --> 00:18:07,157
The cue ball smacks very
quickly into the 8-ball rack,
280
00:18:07,458 --> 00:18:09,694
and once it impacts that head ball,
281
00:18:09,895 --> 00:18:11,644
it's going to transfer that energy
282
00:18:11,645 --> 00:18:13,829
to the balls behind it and then
283
00:18:13,830 --> 00:18:17,868
they will all fly out because the
energy is transferred to all of them.
284
00:18:19,730 --> 00:18:23,736
If a large flare shoots enough
high energy particles at once,
285
00:18:23,837 --> 00:18:26,472
strange things start to happen.
286
00:18:28,196 --> 00:18:30,512
This is actual footage
287
00:18:30,513 --> 00:18:32,519
of a sunquake.
288
00:18:33,174 --> 00:18:34,493
In 1998
289
00:18:34,494 --> 00:18:36,643
there was a solar flare up in the
290
00:18:36,644 --> 00:18:40,361
corona that was so powerful
that the material flying down
291
00:18:40,462 --> 00:18:42,038
toward the surface of the Sun
292
00:18:42,239 --> 00:18:44,238
actually slapped the surface and
293
00:18:44,239 --> 00:18:46,962
caused ripples to spread out from there.
294
00:18:48,000 --> 00:18:50,761
While thay may look
like ripples on a pot,
295
00:18:50,762 --> 00:18:53,618
these are actually waves two miles high
296
00:18:53,663 --> 00:18:55,867
travelling at a maximum velocity of
297
00:18:55,868 --> 00:18:58,725
250 thousand miles per hour.
298
00:18:59,326 --> 00:19:01,340
The 1998 sunquake
299
00:19:01,341 --> 00:19:04,692
would have measured an
11.3 on the Richter scale.
300
00:19:04,793 --> 00:19:06,984
More than one million times stronger
301
00:19:06,985 --> 00:19:09,422
than the 1989 earthquake that
302
00:19:09,423 --> 00:19:11,578
shook San Francisco.
303
00:19:14,914 --> 00:19:18,084
In order to shake the
surface of the Sun that much,
304
00:19:18,185 --> 00:19:21,936
the solar flare had to release
a colossal amount of energy.
305
00:19:23,155 --> 00:19:25,535
It turns out it's almost
the same amount of energy
306
00:19:25,536 --> 00:19:29,836
as if you cover the entire landmass
of the Earth with dinamite,
307
00:19:30,037 --> 00:19:31,420
about a yard thick.
308
00:19:33,857 --> 00:19:35,578
And set it all off at once.
309
00:19:38,322 --> 00:19:40,222
So, these explosions are not small.
310
00:19:43,936 --> 00:19:48,576
Earthquakes aren't the only natural
disasters with equivalents on the Sun.
311
00:19:51,845 --> 00:19:55,361
A flare can also
kick-off a solar tsunami,
312
00:19:56,549 --> 00:19:59,841
as waves of plasma in the
Sun's atmosphere rock it up
313
00:19:59,842 --> 00:20:02,639
at 700 thousand miles per hour,
314
00:20:02,740 --> 00:20:05,309
spreading around the
entire face of the star
315
00:20:05,310 --> 00:20:07,183
in a matter of hours.
316
00:20:18,016 --> 00:20:20,247
While sunquakes and solar tsunamis
317
00:20:20,248 --> 00:20:22,088
pose no danger to Earth,
318
00:20:22,089 --> 00:20:23,781
the violent action of a flare
319
00:20:23,782 --> 00:20:26,153
frequently triggers dangerous eruptions
320
00:20:26,154 --> 00:20:30,435
called coronal mass ejections, or CMEs.
321
00:20:31,789 --> 00:20:32,966
In a CME
322
00:20:32,967 --> 00:20:35,357
energy from a flare flings a blob of
323
00:20:35,358 --> 00:20:37,788
highly charged radioactive plasma
324
00:20:37,789 --> 00:20:39,731
out of the solar atmosphere.
325
00:20:40,290 --> 00:20:41,826
Coronal mass ejections
326
00:20:41,827 --> 00:20:44,214
range in speeds, but they can occur
327
00:20:44,215 --> 00:20:45,902
as quick as
328
00:20:45,903 --> 00:20:48,758
800-900 miles per second,
329
00:20:48,959 --> 00:20:50,958
which is extremely fast and they
330
00:20:50,959 --> 00:20:53,636
expell a massive amount of material.
331
00:20:53,837 --> 00:20:56,775
It can be the same amount of
mass as, say, mount Everest,
332
00:20:56,776 --> 00:20:58,749
coming out from the Sun and
333
00:20:58,750 --> 00:21:00,715
flying out into space.
334
00:21:01,706 --> 00:21:04,699
Where does this blob of
superheated radioactive
335
00:21:04,700 --> 00:21:07,292
plasma go when it leaves the Sun?
336
00:21:07,393 --> 00:21:10,900
Sometimes it sails out
harmlessly into space.
337
00:21:11,001 --> 00:21:14,884
Other times it may head closer to home.
338
00:21:15,829 --> 00:21:18,205
Coronal mass ejections from the Sun
339
00:21:18,206 --> 00:21:22,077
are perhaps the most dangerous
threat you've never heard of.
340
00:21:22,178 --> 00:21:24,237
Also known as solar storms,
341
00:21:24,338 --> 00:21:27,741
they hurl a large masses
of supercharged particles
342
00:21:27,742 --> 00:21:30,845
across 93 million miles of space.
343
00:21:30,946 --> 00:21:34,828
Most take several days to
travel from the Sun to the Earth,
344
00:21:34,929 --> 00:21:37,445
but some rocket across the Solar System
345
00:21:37,546 --> 00:21:39,979
at up to 6 million miles an hour,
346
00:21:39,980 --> 00:21:43,266
reaching our planet
in less than 16 hours.
347
00:21:44,815 --> 00:21:48,184
These storms can induce
currents in the outer atmosphere
348
00:21:48,185 --> 00:21:51,337
knocking out satellites and
cross-country power grids
349
00:21:51,338 --> 00:21:52,899
and carry the potential to
350
00:21:52,900 --> 00:21:55,478
wreak just as much
havoc on our infrastructure
351
00:21:55,479 --> 00:21:57,701
as a hurricane or a tornado.
352
00:21:58,802 --> 00:22:01,251
But who on Earth is keeping an eye
353
00:22:01,252 --> 00:22:04,632
on this potentially
hazardous cosmic blasts?
354
00:22:06,562 --> 00:22:08,127
This is the headquarters
355
00:22:08,128 --> 00:22:11,625
of the National Oceanic and
Atmospheric Administration,
356
00:22:11,626 --> 00:22:14,950
home to the US government's
national weather service.
357
00:22:15,354 --> 00:22:18,511
Their daily forecasts,
watches and warnings
358
00:22:18,512 --> 00:22:22,312
are essential information for
everyday life on our planet.
359
00:22:23,633 --> 00:22:27,281
But there is a lesser known
group of forecasters working here
360
00:22:28,819 --> 00:22:32,769
in a special division called
"The Space Environment Center".
361
00:22:34,516 --> 00:22:37,312
Out primary job is to monitor the Sun
362
00:22:37,413 --> 00:22:40,170
and put out the alerts,
watches and warnings
363
00:22:40,171 --> 00:22:41,574
for solar activity.
364
00:22:41,844 --> 00:22:44,299
Good morning and welcome
to our *10 briefing.
365
00:22:44,400 --> 00:22:47,844
We have one long duration
C-flare from the east limb,
366
00:22:47,945 --> 00:22:49,928
that's a possible CME.
367
00:22:50,029 --> 00:22:52,920
We have not had protons
but we have had electrons.
368
00:22:53,221 --> 00:22:55,127
One thing you notice
is that this region
369
00:22:55,128 --> 00:22:56,687
produced all the activity
in december
370
00:22:56,688 --> 00:22:59,739
so things might be picking up
here in the next couple of weeks.
371
00:22:59,830 --> 00:23:01,507
These space forecasters
372
00:23:01,508 --> 00:23:03,728
are on high alert for solar storms
373
00:23:03,729 --> 00:23:05,912
that might disrupt life on Earth.
374
00:23:06,745 --> 00:23:10,037
Solar storm clouds are made
up of charged particles,
375
00:23:10,038 --> 00:23:12,519
so they are initially
diverted around the planet
376
00:23:12,520 --> 00:23:14,257
by our magnetic field,
377
00:23:14,258 --> 00:23:17,174
just like waves breaking
around the bow of a boat.
378
00:23:17,575 --> 00:23:19,343
That turns out to be very important
379
00:23:19,344 --> 00:23:21,906
because if it impacted the
outer atmosphere directly,
380
00:23:21,907 --> 00:23:25,239
it would knock little bits of
the atmosphere off into space.
381
00:23:25,340 --> 00:23:27,700
One reason why Mars
doesn't have an atmosphere
382
00:23:27,701 --> 00:23:30,238
is that it doesn't have a
strong internal magnetic field.
383
00:23:31,001 --> 00:23:32,815
And so gradually over
384
00:23:32,816 --> 00:23:34,831
millions or maybe billions of years,
385
00:23:34,832 --> 00:23:37,408
the atmosphere was gradually
knocked off into space
386
00:23:37,409 --> 00:23:39,162
by the influence of the solar wind
387
00:23:39,163 --> 00:23:41,962
and by the CMEs that
came past the planet.
388
00:23:44,363 --> 00:23:48,827
But our magnetic field is not the
perfect force field of sci-fi movies.
389
00:23:50,472 --> 00:23:52,563
Some particles can penetrate it
390
00:23:52,564 --> 00:23:55,045
charging up the upper atmosphere.
391
00:23:55,046 --> 00:23:58,535
Solar storms will even bend and
break the magnetic field lines
392
00:23:58,536 --> 00:24:00,386
on the far side of the Earth,
393
00:24:00,387 --> 00:24:04,043
allowing charged particles to
zip back down the field lines
394
00:24:04,044 --> 00:24:06,015
toward the north and south poles.
395
00:24:06,016 --> 00:24:09,490
Extremely powerful storms
distort the magnetic field
396
00:24:09,491 --> 00:24:12,529
even futher, inducing electric currents
397
00:24:12,530 --> 00:24:14,309
that span the continents.
398
00:24:15,962 --> 00:24:19,797
When this happens technology
like long-distance powerlines,
399
00:24:19,798 --> 00:24:21,996
can become overloaded.
400
00:24:22,697 --> 00:24:26,133
It can cause damage to trasformers
at either end of the line.
401
00:24:26,406 --> 00:24:28,817
In fact, in 1989
402
00:24:28,918 --> 00:24:31,630
most of the canadian province
of Quebec
403
00:24:31,676 --> 00:24:34,658
blacked-out because
a transformer was blown out
404
00:24:34,659 --> 00:24:36,180
by a solar event.
405
00:24:37,986 --> 00:24:40,329
If we have that storm that hits our
406
00:24:40,330 --> 00:24:42,669
communication system and hits our
407
00:24:42,681 --> 00:24:45,833
our power companies and all these
things that we depend on,
408
00:24:46,994 --> 00:24:49,718
there is all kinds of chaos
that can lay out there.
409
00:24:54,155 --> 00:24:56,948
If power operators have time to react,
410
00:24:56,949 --> 00:24:58,295
thay can reduce the current
411
00:24:58,296 --> 00:24:59,897
being sent over their wires
412
00:24:59,918 --> 00:25:02,121
and avert disaster.
413
00:25:05,245 --> 00:25:07,140
Satellite operators can also
414
00:25:07,141 --> 00:25:08,868
prepare for the onslaught
415
00:25:08,869 --> 00:25:10,743
with proper warning.
416
00:25:10,744 --> 00:25:12,999
When there's a big space storm coming,
417
00:25:13,000 --> 00:25:15,806
they'll actually put some
of their satellites to sleep,
418
00:25:16,007 --> 00:25:17,499
so that the storm
419
00:25:17,500 --> 00:25:19,750
doesn't cause an electrical short
420
00:25:19,751 --> 00:25:22,138
or otherwise somehow
knock out the satellite.
421
00:25:22,139 --> 00:25:24,672
So the more warning time
they have, the better.
422
00:25:28,279 --> 00:25:29,776
We wouldn't go sailing
423
00:25:29,777 --> 00:25:31,751
unless we knew what the
weather is going to be.
424
00:25:32,639 --> 00:25:35,453
Similarly when we have a large system
425
00:25:35,454 --> 00:25:38,960
like a power system or a
telephone grid that can be affected
426
00:25:38,961 --> 00:25:40,800
by the weather in space,
427
00:25:40,805 --> 00:25:42,773
we need to know what the
weather is going to be
428
00:25:42,774 --> 00:25:44,650
so that we can try and mitigate it.
429
00:25:46,670 --> 00:25:50,654
Solar storms can also disrupt
high frequency radiocommunications
430
00:25:50,655 --> 00:25:52,241
used by aircraft.
431
00:25:52,242 --> 00:25:53,700
In the 1980's
432
00:25:53,701 --> 00:25:57,882
Airforce One was transporting
president Reagan on a trip to China
433
00:25:57,883 --> 00:26:00,173
when a solar storm struck.
434
00:26:00,474 --> 00:26:02,366
All communications were lost
435
00:26:02,367 --> 00:26:03,877
for several hours,
436
00:26:03,878 --> 00:26:05,800
effectively severing the head of
437
00:26:05,801 --> 00:26:07,668
the United States government.
438
00:26:08,669 --> 00:26:11,277
The urgency is just
like our ERS weather.
439
00:26:13,161 --> 00:26:15,037
When we have a tornado warning
440
00:26:15,038 --> 00:26:17,462
we know the urgency to
get that out to the public
441
00:26:17,478 --> 00:26:19,580
to let the people know
that this is happening.
442
00:26:19,581 --> 00:26:21,458
The same thing is with space weather.
443
00:26:21,459 --> 00:26:23,326
Users of this information
444
00:26:23,327 --> 00:26:25,623
need to know it and
they need to know it now.
445
00:26:27,089 --> 00:26:30,547
Just a few hours back we
experienced a coronal mass ejection.
446
00:26:30,548 --> 00:26:33,164
We wanna see where this blast
is going out,
447
00:26:33,165 --> 00:26:34,624
and then we can measure
that and see
448
00:26:34,625 --> 00:26:37,625
how long it might take from
that to reach the Earth from the Sun.
449
00:26:40,070 --> 00:26:43,395
We're seeing a very huge explosion
450
00:26:43,496 --> 00:26:45,548
of material that's coming out
451
00:26:45,549 --> 00:26:48,223
and if you look at
this small image here,
452
00:26:48,162 --> 00:26:49,925
here's the Sun that's covered up,
453
00:26:49,926 --> 00:26:53,574
and look at the mass that's
being thrown out into space.
454
00:26:53,667 --> 00:26:55,106
So it's huge, very huge.
455
00:26:56,842 --> 00:27:00,710
Because magnetic field lines emanate
from the North and South Poles,
456
00:27:00,810 --> 00:27:04,924
energy from solar storms has
easy access to those regions.
457
00:27:05,164 --> 00:27:08,668
For that reason, experts
worry that airplane passengers
458
00:27:08,743 --> 00:27:11,623
flying over the Poles
during a powerful storm,
459
00:27:11,730 --> 00:27:14,890
might be exposed to
harmful levels of radiation,
460
00:27:15,103 --> 00:27:18,781
perhaps are those equal
to a hundred chest x-rays.
461
00:27:19,233 --> 00:27:22,493
It's not something that we want to
mess around with, because we never know
462
00:27:22,517 --> 00:27:24,679
when that radiation might
all of a sudden become
463
00:27:24,737 --> 00:27:27,943
a lot more intense while
there's an airplane in the sky.
464
00:27:28,338 --> 00:27:31,719
The threat from solar radiation
is just one more reason
465
00:27:31,755 --> 00:27:34,843
for scientists to keep a
close watch on our Sun.
466
00:27:34,890 --> 00:27:38,388
It matters, especially in modern
times, what the Sun is doing.
467
00:27:38,389 --> 00:27:39,887
Earth is not an island.
468
00:27:40,049 --> 00:27:43,466
We are participant in the
activities of the Solar System.
469
00:27:44,012 --> 00:27:47,830
Sunspots are the triggers
for more severe solar storms,
470
00:27:47,831 --> 00:27:50,352
so forecasters track them carefully,
471
00:27:50,383 --> 00:27:53,459
as they rotate across
the surface of the Sun.
472
00:27:53,589 --> 00:27:59,377
Location, location, location. We see
CMEs all the time from the Sun.
473
00:27:59,583 --> 00:28:04,065
A lot of them, as the center is rotated
around, are from the backside of the Sun.
474
00:28:05,451 --> 00:28:09,291
That would not be face towards the
Earth, so that would be less of a concern.
475
00:28:10,291 --> 00:28:15,148
As the Sun rotates around and that active
region gets more into the center of the disk,
476
00:28:15,195 --> 00:28:19,105
looking at us, then that's
when we would be concerned with.
477
00:28:19,223 --> 00:28:24,115
From the center of the Sun, as
it rotates around, is the kill zone.
478
00:28:32,707 --> 00:28:36,230
As the sunspot rotates around and
begins to face directly at Earth,
479
00:28:36,289 --> 00:28:38,942
that's when we really have
to worry about a storm.
480
00:28:39,012 --> 00:28:41,595
If a big storm leaves off then,
481
00:28:41,654 --> 00:28:46,361
it can aim directly at Earth, and the full
force of the storm slams into the planet.
482
00:28:51,170 --> 00:28:54,040
It's like a shotgun
aiming at a target.
483
00:28:56,142 --> 00:28:58,068
The more dead on the shot,
484
00:28:59,159 --> 00:29:02,365
the more likely serious
damage will be inflicted.
485
00:29:09,874 --> 00:29:14,418
With great danger also
comes astonishing beauty.
486
00:29:15,478 --> 00:29:19,986
Solar storms generate
majestic planetary lightshows.
487
00:29:20,391 --> 00:29:24,207
The shimmering courtains
of colour called the Aurora.
488
00:29:28,137 --> 00:29:32,375
Auroras work like neon
signs, on an enormous scale.
489
00:29:33,451 --> 00:29:39,099
In a neon sign, electricity introduces
charged particles into a gas-filled tube.
490
00:29:39,315 --> 00:29:42,802
The particles in the gas are
excited and start to glow.
491
00:29:42,906 --> 00:29:46,687
If the tube has only neon
inside, it will glow red.
492
00:29:46,730 --> 00:29:51,732
By adding other gases, like argon, a
whole range of colors can be produced.
493
00:29:52,009 --> 00:29:56,869
The neon sign is driven by the
electric field inside the tube,
494
00:29:56,903 --> 00:30:02,474
whereas the Auroras are actually driven by
the magnetic field and energy from the Sun.
495
00:30:03,261 --> 00:30:06,044
As the energetic
particles in a solar storm
496
00:30:06,079 --> 00:30:09,508
stream along Earth's magnetic
field towards the Poles,
497
00:30:09,596 --> 00:30:14,245
they excite elements in our
atmosphere causing them to glow.
498
00:30:22,014 --> 00:30:25,454
Oxygen molecules emit
a green or red color.
499
00:30:25,497 --> 00:30:29,297
And nytrogen emits
pinks, blues and violets.
500
00:30:31,374 --> 00:30:34,473
While these ghostly lights are
usually confined to the Poles,
501
00:30:34,497 --> 00:30:38,673
extremely strong solar storms can
drive them closer to the Equator.
502
00:30:39,185 --> 00:30:44,116
In 1859 a geomagnetic storm
ignited by a huge solar flare
503
00:30:44,316 --> 00:30:47,287
created Auroras as far south as Rome.
504
00:30:47,999 --> 00:30:51,533
The 1859 storm was an
unusually powerful event
505
00:30:51,556 --> 00:30:55,192
that some have called
"the perfect solar storm".
506
00:30:55,274 --> 00:30:59,041
The 1859 storm taught us a little
something about what the Sun can do.
507
00:30:59,082 --> 00:31:03,414
The storm was so intense and
the alignment was so perfect,
508
00:31:03,485 --> 00:31:06,491
that it simply overwhelmed
Earth's natural defenses.
509
00:31:10,816 --> 00:31:15,156
A huge solar flare erupts
on the surface of the Sun.
510
00:31:16,750 --> 00:31:20,496
Less than a day later
and 93 million miles away,
511
00:31:20,555 --> 00:31:25,214
the wires the carry communications
across the Earth, begin to spark.
512
00:31:25,273 --> 00:31:27,877
Business grinds to a halt worldwide
513
00:31:27,878 --> 00:31:31,746
as wild fires are ignited
by the smoldering lines.
514
00:31:31,910 --> 00:31:37,699
At the same time, colorful Auroras light
up the skies of cities around the globe.
515
00:31:38,185 --> 00:31:43,305
Earth has just been visited
by the perfect solar storm.
516
00:31:43,430 --> 00:31:47,187
The Sun kicked up this
just incredible solar flare
517
00:31:47,257 --> 00:31:50,715
and a massive amount of
energy headed towards Earth.
518
00:31:51,349 --> 00:31:54,904
Not only was this storm one of
the two most powerul on record,
519
00:31:54,963 --> 00:31:57,276
it was also one of the fastest.
520
00:32:00,047 --> 00:32:03,532
Ejecting from a sunspot
aimed directly at Earth,
521
00:32:03,555 --> 00:32:08,221
it raced from the Sun to
our planet in less than 18 hours.
522
00:32:12,012 --> 00:32:16,697
Now, it takes a really fast
rocketship years to get to the Sun.
523
00:32:16,995 --> 00:32:19,801
This storm, this cloud
of electrified particles,
524
00:32:19,802 --> 00:32:22,091
managed to get here in less than a day.
525
00:32:22,173 --> 00:32:23,711
That's incredibly fast.
526
00:32:25,945 --> 00:32:30,689
Fortunately, the perfect
solar storm took place in 1859,
527
00:32:30,900 --> 00:32:35,448
when the only technology vulnerable
to the onslaught was the telegraph.
528
00:32:36,435 --> 00:32:40,591
Since the era in wich we've become
dependant on high technology,
529
00:32:40,650 --> 00:32:43,996
we've yet to see another
perfect solar storm.
530
00:32:44,532 --> 00:32:48,090
The question remains:
Could it happen again?
531
00:32:48,341 --> 00:32:52,063
What if we have another one like that?
Can we have another perfect storm?
532
00:32:52,181 --> 00:32:55,598
I'd say yes we can,
there's no doubt about that.
533
00:32:55,734 --> 00:33:03,663
The effects that would be on us today
compared to 1859 could be devastating.
534
00:33:07,843 --> 00:33:12,325
The effects on Earth and on
our communication systems,
535
00:33:12,384 --> 00:33:14,908
we don't exactly know.
That's the scary part.
536
00:33:15,855 --> 00:33:19,248
It's likely that our modern
technologies would be battered
537
00:33:19,284 --> 00:33:22,278
like beachfront houses
during a hurricane.
538
00:33:25,967 --> 00:33:30,230
Imagine if we lost all the satellites
that relay cellphone calls,
539
00:33:30,253 --> 00:33:32,977
television signals
and bank transactions.
540
00:33:33,079 --> 00:33:34,661
And what if at the same time,
541
00:33:34,708 --> 00:33:40,826
the failure of power grids cascaded whole
regions into darkness for hours, or weeks.
542
00:33:42,240 --> 00:33:45,684
If these essential services
couldn't be restored quickly,
543
00:33:45,709 --> 00:33:48,417
chaos wouldn't be far behind.
544
00:33:51,604 --> 00:33:54,258
It would definitely be
a ripple effect upon society
545
00:33:54,317 --> 00:33:57,064
and every man and woman and
child that lives on this Earth.
546
00:33:58,772 --> 00:34:02,505
Solar storms can be as hard
to predict as hurricanes.
547
00:34:02,942 --> 00:34:07,318
While forecasters lack the technology
to foretell the next pefect storm,
548
00:34:07,361 --> 00:34:10,153
they do know that one
would be more likely to hit
549
00:34:10,165 --> 00:34:14,110
at the peek of the Sun's
eleven-year sunspot cycle.
550
00:34:14,460 --> 00:34:18,540
What happens is the Sun reverses
the direction of its magnetic field
551
00:34:18,541 --> 00:34:19,723
every eleven years.
552
00:34:19,770 --> 00:34:23,081
So in 22 years it reverses
and comes back to where it was.
553
00:34:23,398 --> 00:34:26,275
As we near the reversal
every eleven years,
554
00:34:26,334 --> 00:34:31,283
the number of sunspots increases and
there's a spike in solar activity.
555
00:34:31,306 --> 00:34:33,343
We call that period solar maximum
556
00:34:33,437 --> 00:34:37,212
and those periods are
interspersed about 5 years apart
557
00:34:37,213 --> 00:34:39,683
from periods we call solar minimum.
558
00:34:40,806 --> 00:34:43,158
So you have this eleven
year back and forth
559
00:34:43,159 --> 00:34:45,831
between the Sun being
sometimes very feroscious,
560
00:34:45,878 --> 00:34:49,878
and it goes crazy and it's like the 4th
of July with fireworks all the time.
561
00:34:49,901 --> 00:34:51,392
And then it starts to ramp down
562
00:34:51,393 --> 00:34:53,940
and for a few years it
gets quieter until we get to
563
00:34:53,975 --> 00:34:58,087
a low point where there is a firecracker
now and then but not a lot going on.
564
00:34:58,333 --> 00:35:02,936
Just like hurricane seasons,
solar maximums vary in intensity.
565
00:35:03,237 --> 00:35:07,030
Some produce many more
powerful storms than others.
566
00:35:07,276 --> 00:35:11,503
Although we're currently at solar
minimum, scientists are watching carefully
567
00:35:11,522 --> 00:35:15,315
to see what mayhem the next
solar max might unleash.
568
00:35:15,350 --> 00:35:18,000
The last solar maximum was in about 2001
569
00:35:18,023 --> 00:35:21,968
and so the next one ought to be about
2012, but there are different predictions.
570
00:35:22,011 --> 00:35:25,460
The whole field of solar physicists
is basically waiting with bated breath
571
00:35:25,461 --> 00:35:26,978
to see what actually happens.
572
00:35:27,255 --> 00:35:30,660
There are some wildly divergent
opinions on what's gonna happen.
573
00:35:30,766 --> 00:35:34,324
One group is suggesting
that this next solar cycle
574
00:35:34,325 --> 00:35:37,114
could be the strongest in modern times.
575
00:35:40,114 --> 00:35:45,461
If those predictions are correct,
Earth could be in for a wild ride.
576
00:35:45,766 --> 00:35:49,618
We might have to worry about
a repeat of the 1859 event.
577
00:35:49,682 --> 00:35:52,511
If that would happen today
it would wreak untold damage.
578
00:35:52,593 --> 00:35:55,326
We're gonna learn a whole lot
about what can happen
579
00:35:55,357 --> 00:35:58,070
to modern technology
when the Sun bows its top.
580
00:35:59,723 --> 00:36:02,505
Much of the violence in the Sun
erupts here,
581
00:36:02,608 --> 00:36:06,187
in the hellish outer atmosphere
known as the corona.
582
00:36:06,948 --> 00:36:10,642
This region has long held one
of the great solar mysteries.
583
00:36:10,897 --> 00:36:15,431
Because even though it's half a million
miles from the heat-generating core,
584
00:36:15,541 --> 00:36:18,212
it burns at millions of degrees.
585
00:36:18,489 --> 00:36:21,599
This seems to violate the very laws
of physics.
586
00:36:22,235 --> 00:36:24,687
That's very strange.
I have a thermometer here.
587
00:36:24,771 --> 00:36:27,400
If I hold the thermometer
close to the fire,
588
00:36:27,760 --> 00:36:29,581
it reads a very high reading.
589
00:36:29,669 --> 00:36:32,628
Where the probe is right now
it's over 200 degrees.
590
00:36:33,019 --> 00:36:35,967
And if I pull the probe out
a little farther from the fire,
591
00:36:36,071 --> 00:36:38,497
ok, it drops down to about 90 degrees.
592
00:36:39,165 --> 00:36:42,452
Now, the farther I get from the center,
the cooler it gets.
593
00:36:42,677 --> 00:36:46,804
In the atmosphere, the corona of the Sun,
the temperature soars as hot as the core.
594
00:36:46,903 --> 00:36:50,054
That's as if, I were to say,
well, way off behind me there,
595
00:36:50,106 --> 00:36:52,950
the heat from the fire
is as hot as the fire itself,
596
00:36:53,054 --> 00:36:55,164
even though it's very far from the fire.
597
00:36:56,023 --> 00:36:59,884
What force could possibly cause
the superheating of the corona?
598
00:37:00,535 --> 00:37:03,091
The answer will rock you.
599
00:37:05,292 --> 00:37:09,247
The hellish solar corona
rages at millions of degrees.
600
00:37:09,586 --> 00:37:12,236
For centuries scientists
have been baffled
601
00:37:12,372 --> 00:37:15,113
how anything so far from the Sun's core
602
00:37:15,169 --> 00:37:17,436
could still burn so hot.
603
00:37:18,168 --> 00:37:22,771
Recently, as improved satellites offered
a closer view of the solar surface,
604
00:37:22,932 --> 00:37:25,066
clues began to emerge.
605
00:37:25,500 --> 00:37:29,872
Below the corona
the Sun's surface is literally boiling.
606
00:37:30,414 --> 00:37:33,252
The reason is that
the entire surface of the Sun
607
00:37:33,299 --> 00:37:37,348
is covered with convection cells,
hot material from the inside of the Sun,
608
00:37:37,520 --> 00:37:41,516
that rises up through, reaches the
surface, cools off by glowing,
609
00:37:41,623 --> 00:37:44,649
giving off sunlight
and then sinks back down.
610
00:37:44,976 --> 00:37:48,597
Each bubble of material that comes up
is about the size of Texas.
611
00:37:48,680 --> 00:37:52,775
It spreads out across the surface,
cools off and sinks down in 5 minutes.
612
00:37:53,000 --> 00:37:56,266
So, that's a tremendously
violent process
613
00:37:56,339 --> 00:37:59,232
that's happening in, literally,
almost a million places
614
00:37:59,263 --> 00:38:03,301
over the entire surface of the Sun,
all the time around the clock, 24/7.
615
00:38:06,001 --> 00:38:09,883
This boiling is not only violent,
it's also extremely loud.
616
00:38:11,172 --> 00:38:14,297
The Sun is a tremendously loud place.
617
00:38:17,379 --> 00:38:20,666
If you could imagine covering
the entire surface of the Sun
618
00:38:20,906 --> 00:38:25,122
with speakers being driven as hard as the
loudest rock concert you've ever been to,
619
00:38:25,477 --> 00:38:29,974
that would be comparable to how loud
it really is on the surface of the Sun.
620
00:38:31,106 --> 00:38:34,468
The Sun's churning surface
creates enough sound energy
621
00:38:34,531 --> 00:38:37,891
to superheat the corona
to millions of degrees.
622
00:38:38,550 --> 00:38:42,281
Scientists believe that a combination
of these sound waves and energy
623
00:38:42,323 --> 00:38:43,993
from the Sun's magnetic field
624
00:38:44,070 --> 00:38:48,338
is responsible for the extreme
temperatures found in the corona.
625
00:38:49,674 --> 00:38:52,857
The only time you can
actually see the corona from Earth
626
00:38:52,998 --> 00:38:57,412
is at the climax of one of the most
dazzling displays in the Solar System,
627
00:38:57,636 --> 00:38:59,661
a total solar eclipse.
628
00:39:00,469 --> 00:39:02,509
Before scientists understood them,
629
00:39:02,561 --> 00:39:06,318
these awe inspiring events
instilled only fear.
630
00:39:06,610 --> 00:39:11,034
The ancient Chinese believed
that a dragon was devouring the Sun.
631
00:39:11,619 --> 00:39:14,666
So what's really happening
in a solar eclipse?
632
00:39:14,781 --> 00:39:19,147
In simplest terms it's when the
Moon blocks our view of the Sun.
633
00:39:20,493 --> 00:39:23,718
Imagine that you're sitting in a
movies watching very happily
634
00:39:23,739 --> 00:39:26,389
something going on on the screen
and then somebody
635
00:39:26,546 --> 00:39:29,635
in the row in front of you comes across
636
00:39:29,859 --> 00:39:31,612
and blocks your view.
637
00:39:31,731 --> 00:39:33,776
In a movie theater
you might not want that person
638
00:39:33,777 --> 00:39:35,478
to come across in front of you,
but at...
639
00:39:35,479 --> 00:39:39,277
an eclipse we're very lucky to have
the Moon come across the Sun,
640
00:39:39,313 --> 00:39:41,807
and we're lucky to have it come
right across the middle.
641
00:39:42,745 --> 00:39:47,254
We're also lucky that the Moon, although
it's 400 times smaller than the Sun,
642
00:39:47,286 --> 00:39:50,322
is also 400 times closer to us.
643
00:39:50,458 --> 00:39:53,458
This cosmic coincidence means
that the two objects
644
00:39:53,531 --> 00:39:56,636
just happen to be the same
apparent size in our sky,
645
00:39:56,724 --> 00:40:00,225
which allows for one
to completely block out the other.
646
00:40:01,832 --> 00:40:04,597
This magnificent cosmic event
only happens
647
00:40:04,629 --> 00:40:08,562
when the path of the Moon intersects the
line between the Earth and the Sun.
648
00:40:08,700 --> 00:40:12,016
The Moon's orbit is tilted slightly
about 5 degrees.
649
00:40:12,125 --> 00:40:15,548
If it wasn't we would have
an eclipse every month.
650
00:40:15,898 --> 00:40:17,327
And then we'd be bored,
651
00:40:17,359 --> 00:40:19,858
but we're not bored because most months
652
00:40:19,949 --> 00:40:22,839
the Moon goes above or below
653
00:40:22,920 --> 00:40:26,542
the place where the line goes
from the Earth to the Sun.
654
00:40:27,897 --> 00:40:30,673
So instead of one every month
we get a total eclipse
655
00:40:30,725 --> 00:40:33,908
somewhere on Earth about
once every year and a half.
656
00:40:34,623 --> 00:40:36,824
As the Moon slides in front of the Sun,
657
00:40:36,862 --> 00:40:39,121
it casts a shadow onto the Earth.
658
00:40:39,241 --> 00:40:41,850
The outer part,
where the shadow is fainter,
659
00:40:41,898 --> 00:40:43,756
is called the penumbra.
660
00:40:44,595 --> 00:40:47,392
If you're standing within the swath
traced by the penumbra,
661
00:40:47,455 --> 00:40:49,479
as it moves along the Earth's surface,
662
00:40:49,526 --> 00:40:51,884
then you'll see only a partial eclipse.
663
00:40:54,391 --> 00:40:57,720
But travel to a spot within the path
of the dark inner shadow,
664
00:40:57,768 --> 00:40:59,124
called the umbra,
665
00:40:59,173 --> 00:41:03,117
and you'll experience
the majesty of a total eclipse.
666
00:41:06,895 --> 00:41:10,558
There's another option if you
can't travel to the path of totality,
667
00:41:10,954 --> 00:41:13,009
wait in one place long enough
668
00:41:13,067 --> 00:41:15,932
and a total eclipse will pass
right over your head
669
00:41:16,036 --> 00:41:18,749
about once every 300 years.
670
00:41:23,287 --> 00:41:26,902
The Sun, that shining star
of our Solar System,
671
00:41:27,037 --> 00:41:31,642
is capable of both astonishing beauty
and ferocious violence.
672
00:41:32,991 --> 00:41:35,203
It seems impossible to believe,
673
00:41:35,391 --> 00:41:37,613
but it won't be around forever.
674
00:41:39,564 --> 00:41:42,976
Eventually even the Sun must die.
675
00:41:43,466 --> 00:41:46,889
The Sun has a fixed amount
of fuel in its core,
676
00:41:47,243 --> 00:41:51,992
it is undergoing fusion
at a rate that you can calculate.
677
00:41:52,274 --> 00:41:54,465
So here's the rate it's using its fuel,
678
00:41:54,810 --> 00:41:56,432
here's how much fuel you have,
679
00:41:56,747 --> 00:42:00,827
so it's a simple calculation
to show when the Sun will die,
680
00:42:01,132 --> 00:42:03,323
and that's in about
a five billion years.
681
00:42:03,930 --> 00:42:06,507
Well, unfortunately the Sun
will not go out with a bang.
682
00:42:06,556 --> 00:42:09,415
It's too small to erupt in a supernova.
683
00:42:10,410 --> 00:42:12,789
However stars do a peculiar thing,
684
00:42:12,821 --> 00:42:16,087
they're one of the few things around
that get hotter as they cool off.
685
00:42:16,993 --> 00:42:20,771
As it exhausts its hydrogen fuel,
our nearest star will cool
686
00:42:20,844 --> 00:42:23,682
and gradually collapse
under the force of gravity.
687
00:42:23,870 --> 00:42:27,177
Energy from this collapse
will start heating up the core again
688
00:42:27,209 --> 00:42:31,988
to hundreds of millions of degrees,
hot enough to start burning helium.
689
00:42:32,849 --> 00:42:34,988
Onto the extra heat
of the helium burning,
690
00:42:35,019 --> 00:42:39,444
the star will expand into
a monstrous orb called a red giant.
691
00:42:39,876 --> 00:42:42,714
It'll get so big it will engulf
692
00:42:43,022 --> 00:42:47,530
the entire orbits of Mercury,
Venus and Earth.
693
00:42:48,488 --> 00:42:49,753
You don't want to be around for that.
694
00:42:49,791 --> 00:42:52,554
You want to be planet-hopping
your way to safety
695
00:42:52,691 --> 00:42:54,444
long before this happens.
696
00:42:55,659 --> 00:42:59,149
The Earth is likely to change its orbit
slightly as the star expands,
697
00:42:59,190 --> 00:43:01,089
so that it won't be engulfed.
698
00:43:01,161 --> 00:43:04,230
Still, talking about global warming,
you wouldn't want to be here.
699
00:43:04,983 --> 00:43:08,897
The outer layers of our Sun will
eventually become so unstable
700
00:43:09,032 --> 00:43:11,244
that they will fly off into space,
701
00:43:11,296 --> 00:43:15,347
leaving behind a small core
about the size of the Earth.
702
00:43:16,057 --> 00:43:18,445
So remember we've shrunk
most of the Sun,
703
00:43:18,477 --> 00:43:21,408
which is a million miles across,
to the size of the Earth which is
704
00:43:21,585 --> 00:43:24,371
more like 6000 miles across.
705
00:43:24,653 --> 00:43:28,957
Our once great star reduced
to a slowly cooling cinder.
706
00:43:29,661 --> 00:43:32,708
Life as we know it on Earth
will cease to exist.
707
00:43:33,303 --> 00:43:35,839
And that is the death of the Sun.
708
00:43:37,665 --> 00:43:40,816
All of this is bad news
for the human race,
709
00:43:41,605 --> 00:43:43,452
but look on the bright side.
710
00:43:44,182 --> 00:43:47,740
We've got five billion years
to prepare for this disaster.
711
00:43:49,222 --> 00:43:52,671
For now, humanity basks
in the glow of a Sun
712
00:43:52,744 --> 00:43:54,822
in the prime of its life.
713
00:43:55,018 --> 00:43:58,869
Science has uncovered many of
the secrets of our nearest star,
714
00:43:59,037 --> 00:44:01,571
but we remain awed
by its beauty,
715
00:44:01,644 --> 00:44:05,171
and ever more wary of its wrath.38442
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