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What Happens If A Star Explodes Near The Earth? | |
YouTube ^ | November 15, 2022 | Veritasium (Derek Alexander Muller)

Posted on 11/24/2022 2:29:38 PM PST by SunkenCiv

What Happens If A Star Explodes Near The Earth?
Veritasium | November 15, 2022
What Happens If A Star Explodes Near The Earth? | Veritasium | November 15, 2022


(Excerpt) Read more at youtube.com ...


TOPICS: Astronomy; Science
KEYWORDS: astronomy; blackhole; brianthomas; catastrophism; clovisimpact; derekalexandermuller; gammarayburst; gammaraybursts; grb; hansthomasjanka; iron60; lukebarnes; neutronstar; ordovician; randallmunroe; scc; science; supernova; veritasium
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The Cycle of Cosmic Catastrophes: Flood, Fire, and Famine in the History of Civilization
The Cycle of Cosmic Catastrophes:
Flood, Fire, and Famine
in the History of Civilization

by Richard Firestone,
Allen West, and
Simon Warwick-Smith


1 posted on 11/24/2022 2:29:38 PM PST by SunkenCiv
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To: SunkenCiv

It will take a long time to clean up


2 posted on 11/24/2022 2:31:05 PM PST by Larry Lucido (Donate! Don't just post clickbait!)
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To: SunkenCiv

I think Rosie O’Donnell blew up once. It wasn’t pretty.


3 posted on 11/24/2022 2:31:59 PM PST by Larry Lucido (Donate! Don't just post clickbait!)
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To: SunkenCiv

Better a star than Uranus.


4 posted on 11/24/2022 2:33:11 PM PST by EvilCapitalist (81 million votes my ass.)
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To: SunkenCiv

Duct tape, Bondo, beer, and hot babes required for clean up


5 posted on 11/24/2022 2:33:25 PM PST by PIF (They came for me and mine ... now its your turn)
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To: Larry Lucido

How big is the star? How far away is the star? Inverse square law is our friend.


6 posted on 11/24/2022 2:34:22 PM PST by Theophilus (It's fake and defective)
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To: SunkenCiv

Is this more severe than Brittany Spears in 2007?


7 posted on 11/24/2022 2:35:44 PM PST by DannyTN
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To: SunkenCiv

Iirc the closest star is like 4.3 light years away.

all the rest of them are much further.

so if you take squares of difference and energy released into account any random average star exploding would have less effect on earth than a typical politician.


8 posted on 11/24/2022 2:37:06 PM PST by algore
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To: Theophilus

If it is Sirius, 16 light years away, then we have a problem. If it is Betelgeuse, 300 light years away, we have a spectacular light show.


9 posted on 11/24/2022 2:37:19 PM PST by 17th Miss Regt
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To: 17th Miss Regt

300 miles away? I thought Betelgeuse was in Chicago?


10 posted on 11/24/2022 2:39:04 PM PST by EvilCapitalist (81 million votes my ass.)
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To: SunkenCiv; dfwgator

Like the one 93 million miles away?

☀ïļðŸŒžðŸ˜Ž

Stupid Sarah sees a face!

ðŸĪŠðŸ˜œ


11 posted on 11/24/2022 2:39:45 PM PST by SaveFerris (Luke 17:28 ... as it was in the days of Lot; they did eat, they drank, they bought, they sold ......)
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To: SunkenCiv
There might be some anger issues and weird clothing choices.


12 posted on 11/24/2022 2:40:16 PM PST by DannyTN
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To: SunkenCiv

well, if it’s our star/sun, problems are over...


13 posted on 11/24/2022 2:44:30 PM PST by Chode (there is no fall back position, there's no rally point, there is no LZ... we're on our own. #FJB)
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To: SunkenCiv
For one thing, it takes forever to get everything cleaned up.

14 posted on 11/24/2022 2:49:31 PM PST by Blurb2350 (posted from my 1500-watt blow dryer)
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Some related keywords, sorted, edited (a bunch of chaff, plus APOD topics removed):

15 posted on 11/24/2022 2:51:14 PM PST by SunkenCiv (Imagine an imaginary menagerie manager imagining managing an imaginary menagerie.)
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To: 75thOVI; Abathar; agrace; aimhigh; Alice in Wonderland; AnalogReigns; AndrewC; aragorn; ...



16 posted on 11/24/2022 2:51:24 PM PST by SunkenCiv (Imagine an imaginary menagerie manager imagining managing an imaginary menagerie.)
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To: EvilCapitalist

Nice job, workin’ that in. :^)


17 posted on 11/24/2022 2:52:24 PM PST by SunkenCiv (Imagine an imaginary menagerie manager imagining managing an imaginary menagerie.)
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Some of those will buff right out.


18 posted on 11/24/2022 2:52:46 PM PST by SunkenCiv (Imagine an imaginary menagerie manager imagining managing an imaginary menagerie.)
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Transcript
0:00- What would happen if
0:01a star exploded near the earth?
0:04Well, the nearest star to Earth, of course, is the sun,
0:07and it is not going to explode,
0:09but if it had eight times the mass,
0:12then it would go supernova at the end of its life.
0:15So what would that look like?
0:17Well, as noted by xkcd if you held up
0:20a hydrogen bomb right to your eyeball and detonated it,
0:25that explosion would still be a billion times less bright
0:30than watching the sun go supernova from Earth.
0:36That's how insanely powerful supernova explosions are.
0:39They are the biggest explosions in the universe.
0:42When we see supernovae in other galaxies,
0:45they are brighter than the combined light
0:48of hundreds of billions of stars, so bright, in fact,
0:52that they appear to come out of nowhere.
0:55On the 8th of October, 1604,
0:57the astronomer Johannes Kepler looked up into the night sky
1:01and noticed a bright star he had never seen before.
1:05It was brighter than all the other stars in the sky
1:08and about as bright as the planet Jupiter.
1:12On moonless nights, it was bright enough to cast a shadow.
1:16Kepler published his observations
1:18of this star in a book called "De Stella Nova,"
1:20which means "about a new star" in Latin.
1:24Kepler thought he was witnessing the birth of a new star,
1:28but it was actually a star's violent death.
1:32Over the following year and a half,
1:33the light faded until it was no longer visible,
1:37but the name stuck.
1:39Even once we learned what was really happening in the 1930s,
1:42the violent final explosion for stars
1:45between about 8 and 30 solar masses
1:47has been called a supernova.
1:51But how exactly a star explodes is not
1:54what most people think.
1:57For most of a star's life, it exists in a stable balance.
2:00In its core, it fuses lighter elements together
2:03to make heavier ones, and in the process
2:05it converts a small amount of matter into energy.
2:08This energy is really what keeps the star
2:11from collapsing in on itself.
2:14Gravity compresses the star,
2:16but that force is counteracted by the pressure generated
2:19by the movement of particles inside the star,
2:22and by the pressure of photons released by fusion.
2:26So in effect, stars are propped up by their own light.
2:32If the rate of fusion drops at the center of the star,
2:34the temperature and the pressure decrease.
2:37Gravity starts winning, compressing the star,
2:41but this increases the temperature and pressure in the core,
2:44which increases the rate of fusion.
2:46It's a stable self-regulating system, but there's a problem.
2:51Stars have a finite amount of fuel,
2:54which over time gets used up.
2:56Our sun is about 5 billion years
2:59into its 10-billion-year lifespan.
3:02There are stars dozens of times more massive than the sun,
3:05which you would think would live much longer,
3:07but they actually use up their nuclear fuel faster
3:11A star 20 times the mass of our sun has
3:13a lifespan of just 10 million years,
3:16and more massive stars burn hotter, and even brighter,
3:20but for much shorter lives.
3:22For 90% the life of a star,
3:24the core is only hot enough to fuse hydrogen into helium,
3:29and when the hydrogen runs out,
3:31fusion slows, gravity compresses the core
3:34and its temperature increases to 200 million degrees,
3:38at which point helium fuses into carbon.
3:41There's enough helium to power the star for around
3:44a million years, but as the helium runs out,
3:47the core is, again, compressed and heated.
3:49Carbon starts fusing into neon,
3:51which lasts about 1,000 years,
3:53and then neon fuses into oxygen for a few more years,
3:57then oxygen to silicon for a few months
4:00and at 2.5 billion degrees, silicon fuses
4:03into nickel which decays into iron.
4:07Now, at the heart of this giant star,
4:08there is an iron core building that's only
4:12a few thousand kilometers across.
4:15Iron is where this pattern stops.
4:17Instead of liberating energy as it fuses
4:20into heavier elements, it actually requires energy.
4:24Iron is the most stable element.
4:27So it actually takes energy both
4:28to fuse it into heavier elements
4:30and to break it down into lighter ones.
4:33Both fusion and fission reactions ultimately end up at iron.
4:38The iron core grows,
4:40but the crush of gravity becomes greater
4:42and greater as the rate of fusion drops.
4:45When the iron core is about 1.4 times the mass of our sun,
4:49which is known as the Chandrasekhar limit, the pull
4:52of gravity is so strong that something totally wild happens.
4:56Quantum mechanics takes over.
4:58Electrons run out of room to move,
5:01and they're forced into their lowest energy states,
5:04and they then become absorbed by the protons in the nucleus.
5:09In this process, the protons turn
5:11into neutrons and release neutrinos.
5:15With the electrons gone, the core collapses,
5:18and fast, at about 25% the speed of light.
5:22So what used to be a ball
5:23of iron 3,000 kilometers in diameter becomes
5:27a ball of neutrons just 30 kilometers across.
5:30Essentially, it's a neutron star.
5:33With no outward pressure to hold it up,
5:36the rest of the star caves in.
5:38Also, falling at a quarter of the speed of flight,
5:41it hits the neutron star and bounces off,
5:44creating a huge pressure wave.
5:46But this kinetic energy isn't quite enough
5:49to start a supernova explosion.
5:51No, the thing that really kicks it off
5:53is the humble neutrino.
5:55Now, I normally think of neutrinos
5:57as particles that do basically nothing.
6:00I mean, they interact so rarely with matter
6:02that right now there are 100 trillion neutrinos
6:05passing through your body per second.
6:08It would take a light year of lead just
6:10to give you a 50-50 chance of stopping a neutrino,
6:14and that's because they interact only
6:15through gravity and the weak force
6:18but in a supernova, when the electrons are captured
6:21by the protons, an unbelievable number
6:23of neutrinos is released, around 10^58.
6:28You would think they would just fly off
6:30at nearly the speed of light, but the core
6:33of a supernova is incredibly dense,
6:35about 10 trillion times more dense than lead
6:39and as a result, it traps some of those neutrinos
6:43and captures their energy,
6:45and this is what makes a star go supernova.
6:48A particle that is millions
6:50of times less massive than an electron that barely interacts
6:54with anything is responsible for some
6:57of the largest explosions in the universe.
7:01In that explosion, only 1/100 of 1%
7:05of the energy is released as electromagnetic radiation,
7:08the light that we can see.
7:10Even then, supernova have enough energy
7:12to outshine a whole galaxy.
7:14About 1% of the energy is released as the kinetic energy
7:18of the exploding matter, but the vast majority
7:21of the energy is released in the form
7:24of neutrinos, and neutrinos are actually
7:27the first signal we detect from supernovae,
7:31and that's because after they're generated
7:33in the core, they can escape
7:36before the shockwave reaches the surface,
7:38where the light that we see is generated.
7:41So neutrinos can arrive on Earth hours before the photons,
7:44giving astronomers a chance to aim their telescopes
7:47at the right part of the sky.
7:51I actually used to work
7:52at a neutrino observatory back in college,
7:54and I would work the graveyard shift
7:56between midnight and 8:00 AM.
7:58So if I detected a really big increase
8:01in the neutrino flux during my shift,
8:02it was my job to call and wake up scientists,
8:06so they could go look out for a supernova.
8:09Now, that never actually happened,
8:10but we did have some close calls.
8:12Now, I need to clarify a couple things.
8:15First, not all really massive stars explode.
8:18As they collapse, some form black holes instead,
8:21which means they do not go supernova
8:24and second, there's another way to make a supernova.
8:27Sometimes a white dwarf star, which is incredibly dense,
8:30pulls matter off a nearby star, and when it's mass reaches
8:34that Chandrasekhar limit of 1.4 solar masses,
8:37the white dwarf collapses, creating a supernova.
8:41This is actually the type of supernova that Kepler saw
8:43in 1604, a supernova 20,000 light years from Earth.
8:49Now, because the shocks are asymmetric,
8:51supernova explain neutron stars that can move really fast.
8:56There's a neutron star we've observed with a velocity
8:58of 1,600 kilometers per second, and we think that was caused
9:04by a very asymmetric supernova explosion,
9:07sent it shooting off in the other direction.
9:10Despite only recently learning about how supernovae work,
9:13humans have been observing them for thousands of years.
9:17Ancient Indian, Chinese, Arabic
9:19and European astronomers all observed supernovae,
9:23but they are quite rare.
9:25In a galaxy like our Milky Way,
9:27consisting of 100 billion stars,
9:30there are only about one or two supernovae per century.
9:34A particularly amazing example is the supernova of 1054,
9:39when the light of a supernova 6,500 light years away
9:42reached the earth and was recorded by Chinese astronomers.
9:47If we look to where that supernova was recorded,
9:50we see the Crab Nebula.
9:52It is a giant remnant of radioactive matter,
9:56left behind by the explosion.
9:58In the 1,000 years since the explosion,
10:01the remnant has grown to 11 light years in diameter.
10:05Supernovas produce a lot of cosmic rays.
10:08Cosmic rays are actually particles,
10:10mainly protons and helium nuclei,
10:13and they travel out at very,
10:15very nearly the speed of light.
10:17They have a tremendous amount of energy.
10:20So at what distance could
10:22a supernova cause problems for life on Earth?
10:25The closest stars to us, besides the sun,
10:27are the three stars in Alpha Centauri.
10:30They are 4.4 light years away, but stars do move around
10:35and on average, a star gets within one light year
10:38of Earth every 500,000 years.
10:41So what would happen if such a star went off?
10:46- Yeah, so within a light year, you're easily
10:48within a danger distance from just the kinetic energy.
10:52So I think even at that distance,
10:54you're looking at possibly blowing the atmosphere off.
10:58- But we would also
10:59have other problems to worry about.
11:01Supernovae create conditions that are hot enough
11:03to fuse elements heavier than iron.
11:06In the months after the explosion, these elements
11:09undergo radioactive decay, producing gamma rays
11:12and cosmic rays.
11:14Less than 0.1% of the energy produced
11:16by a supernova is emitted as gamma rays
11:19from these radioactive decays,
11:20but even this tiny percentage can be dangerous.
11:24At a few light years from a supernova,
11:26the radiation could be deadly, though most
11:29of it would be blocked by our atmosphere.
11:33Now, the earth is protected from solar and cosmic radiation
11:36by our atmosphere, and specifically by ozone molecules,
11:41three oxygen atoms bonded together,
11:43but high energy cosmic rays from supernova can come down
11:47and break apart nitrogen molecules in the atmosphere,
11:52and then these bond with oxygen atoms,
11:55which can then break apart ozone,
11:58and so we can lose a lot of our ozone
12:01if there's too many cosmic rays coming
12:03from supernova events, and that can expose us
12:05to all kinds of dangerous radiation coming in from space.
12:09We actually see an increase
12:10in atmospheric NO3 concentrations,
12:13coinciding with supernova explosions.
12:16A supernova within 30 light years is rare,
12:19only happening maybe once every 1 1/2 billion years or so,
12:23but a recent article suggests supernovae could be lethal all
12:26the way out to 150 light years away,
12:30and so those would be much more common.
12:32We actually have evidence
12:34for a supernova that went off 150 light years
12:36from Earth 2.6 million years ago.
12:39It would've been seen by our early human ancestors,
12:42like Australopithecus, and we know this
12:45because there are elements present on Earth
12:47that could only have been deposited by a recent supernova.
12:51In sedimentary rocks at the bottom of the Pacific Ocean,
12:54scientists have found traces of iron-60,
12:57in a layer that was deposited 2.6 million years ago.
13:02Iron-60 is an isotope of iron
13:04with four more neutrons than the most common type of iron.
13:08Iron-60 is really hard to make.
13:10Our sun doesn't make it, nor is it produced, basically,
13:13anywhere else in the solar system.
13:15Iron-60 is made, basically, exclusively
13:18in supernova explosions,
13:20and iron-60 is radioactive.
13:22It has a half life of 2.6 million years.
13:25So every 2.6 million years,
13:27half of the sample decays into cobalt-60.
13:31So all of the iron-60 that was around during the formation
13:34of the earth, 4.5 billion years ago,
13:36has definitely decayed.
13:38So the iron-60 that the scientists measure
13:41is proof of a recent supernova.
13:43Scientists also measured trace amounts of manganese-53
13:47in the same sediments, giving further evidence
13:49supporting the idea that recently there was
13:52an explosion of a nearby supernova.
13:55The supernova that happened 2.6 million years ago
13:58wasn't catastrophic for our ancestors,
14:01but some researchers hypothesized that it could be related
14:04to the mass extinction, which is seen
14:05at the Pliocene-Pleistocene boundary
14:08in the fossil record around the same time.
14:11This extinction wiped out around 1/3 of marine megafauna.
14:15The idea is that the cosmic rays
14:17from the supernova hit particles in our atmosphere,
14:20creating muons, which are charged particles
14:23like the electron, only more than 200 times heavier.
14:26The muon flux for years after the supernova
14:29would've been 150 times higher than normal,
14:33and the bigger the animal, the larger
14:35the radiation dose it would've received from these muons,
14:38which is why megafauna were so disproportionately affected,
14:42and what's more, the animals that lived
14:45in shallower waters were more likely
14:47to become extinct compared to the ones that lived at depth,
14:50where the water would've protected them from muons.
14:54Further evidence for these recent nearby supernovae comes
14:57from our place in the galaxy.
15:00You know, if you look in the space
15:01between the stars in our galaxy, on average,
15:04there are around a million hydrogen atoms per cubic meter.
15:08That may sound like a lot,
15:09but it's basically a perfect vacuum
15:11but for hundreds of light years
15:14in all directions around our solar system,
15:17you find there are 1,000 times fewer hydrogen atoms.
15:21It's like they've all been blown out somewhere,
15:24and our solar system is existing in this cosmic void,
15:28inside a low density bubble.
15:31So that is evidence for maybe tens of supernovae
15:34that would've blown all this material outwards,
15:38but there are cosmic explosions that are even
15:40more deadly than normal supernovae, gamma ray bursts.
15:44Gamma ray bursts were discovered by the Vela satellites,
15:47which were looking for Soviet nuclear tests
15:50but on the 2nd of July, 1967,
15:52the satellites detected a large burst of gamma rays,
15:56which were coming from space.
15:59There are two main sources of gamma ray bursts,
16:02mergers of neutron stars and the core collapses
16:05of gigantic stars called hypernovae.
16:08Hypernovae are caused by stars that are
16:10at least 30 solar masses and rapidly spinning.
16:14Their collapse leads to an explosion 10 times more powerful
16:18than a regular supernova, and it leaves behind a black hole.
16:23The gamma ray bursts caused by hypernovae channel most
16:27of their energy into beams
16:28which are just a few degrees across.
16:32If there was a gamma ray burst within 6,000 light years,
16:35it would decrease the ozone level enough
16:38that it could be catastrophic.
16:40To put this distance in context, a sphere with a radius
16:43of 6,000 light years contains hundreds of millions of stars.
16:49On October 9th, 2022, astronomers detected one
16:52of the most powerful gamma ray bursts ever measured.
16:55It was powerful enough to measurably affect how
16:58the ionosphere bounces radio waves.
17:00The effect on the ionosphere was
17:02around the same as a solar flare,
17:05but this gamma ray burst was located
17:07in a galaxy 2.5 billion light years away.
17:12Astronomers speculate that a gamma ray burst
17:14could have caused the Late Ordovician mass extinction,
17:17which wiped out 85% of marine species 440 million years ago.
17:23There is no direct evidence,
17:25but gamma ray bursts are common enough
17:27that it is estimated that there has been
17:29a 50% chance that there was
17:31an ozone-removing, extinction-causing GRB
17:34in the vicinity of Earth in the last 500 million years.
17:38So if a supernova or a gamma ray burst were
17:41to go off near the earth now,
17:43that would be pretty catastrophic but in an ironic twist,
17:47we kind of owe our existence to these sorts
17:50of explosions because 4.6 billion years ago,
17:54it was probably the shockwave from a nearby supernova
17:58which triggered the collapse of a cloud of gas
18:02and dust that gradually coalesced to form our solar system.
18:06So the sun, the earth and all of us wouldn't be here today
18:11without the explosions of nearby stars.
18:22Figuring out how supernova explode was incredibly difficult.
18:25It took a combination of astrophysics,
18:27particle physics, computer science and mathematics,
18:30and if you wanna develop a better understanding
18:32of our universe, then you should check out
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19 posted on 11/24/2022 2:55:38 PM PST by SunkenCiv (Imagine an imaginary menagerie manager imagining managing an imaginary menagerie.)
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To: SunkenCiv

How many thousand lightyears is “close”?


20 posted on 11/24/2022 2:56:45 PM PST by Tucker39 ("It is impossible so to rightly govern a nation without God and the Bible." George Washington )
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