Death From Space — Gamma-Ray Bursts Explained
Death From Space — Gamma-Ray Bursts Explained

Imagine if you could gather the energy from every star within a hundred million light years. From thousands of galaxies, each with billions of stars. Imagine, you could take this kind of power, and use it to fire the biggest super-weapon in the universe. Imagine the damage you could do. It turns out, you don’t need to imagine it. These exist, and they’re called gamma ray bursts. But what are these cosmic snipers? And what happens if one takes a shot at Earth? To understand gamma ray bursts, we first have to understand gamma rays. Gamma rays are electromagnetic radiation – waves which carry energy just like visible light. Visible light is a tiny part of the electromagnetic spectrum: it’s the part your eyes can see. At lower energies, there are radio waves, microwaves and infrared. And at higher energies: ultraviolet, x-rays and gamma rays. Gamma rays are incredibly powerful. A single gamma ray photon, is more energetic than a million visible photons combined. Their high energy makes gamma rays a form of ionizing radiation. Meaning they are energetic enough, to break apart atomic bonds. This makes them dangerous to you and me. Ionizing radiation disrupts the delicate biochemical machinery that keeps us alive, like a 9mm bullet through a clock. Fortunately, on Earth, the ozone layer blocks gamma rays. Filtering them out before they can harm us. But if the atmosphere blocks gamma rays from space, how were gamma ray bursts (or GRBs) from space ever discovered? During the Cold War, the USA sent up spy satellites, which could detect gamma rays from Soviet nuclear tests in space. They didn’t see any bombs, but they did observe faint bursts coming from space, lasting only a few seconds. To date, this may be the only major scientific discovery made by spy satellites (that we know about anyway). Astronomers use telescopes see different kinds of light to make their discoveries. And these spy satellites gave them a new pair of eyes. They were a mystery for thirty years but eventually, we discovered the source of a GRB: a galaxy six billion light years away. If a GRB can be seen from such a distance, then it must be incredibly energetic. Releasing more energy in a second than the sun will, in its entire ten billion year lifetime. Making GRBs, the brightest events in the universe. So, where do they come from? GRBs, accompany some of the most violent, cataclysmic deaths in the universe, and the birth of black holes. There are two types of gamma ray bursts: short and long, and each has their own source. Long GRBs last about a minute, and scientist think they are produced by supernova: when the core of a massive star collapses to become a black hole. Short GRBs last a second, and are produced when two neutron stars in a binary merge. Over millions of years, their orbits decay by emmiting gravitational waves. Once they are close enough to touch, they crash and splash into each other, forming a black hole. Both supernova and neutron star mergers the same thing: black holes, surrounded by a magnetized disc of gas left over from their parent stars. In these environments, the rotation winds up the magnetic field, which funnels hot jets of particles, traveling at nearly the speed of light. The gas in this funnel creates two tight jets of high energy gamma rays, like a celestial laser gun. So unlike other cosmic explosions, which spread out and fade, GRBs say focused, and can been seen from much further. Any more detail would require too much mathematics for a YouTube video. The universe is full of these cosmic snipers, firing blindly and randomly into the dark, and they’re hitting us all the time. On average, we detect one per day. Fortunately, most are harmless. All the bursts we have detected so far, originated outside the Milky Way, too far away to hurt us. But a nearby GRB could be disastrous, if one goes off within a few light years of us, it would totally cook the surface of the Earth. Or at least, the half that’s facing it. But even a more distant GRB could still end life on Earth. And it wouldn’t need to score a head-shot to kill us. If originating from a few thousand light years away, it would be a hundred light years wide by the time it reaches us, washing over the Solar System like a tidal wave. Again, the ozone layer protects us, but it’s better equipped to handle the trickle of ultraviolet from the sun. A gamma ray burst would overwhelm it, leaving us exposed to deadly solar radiation. Ozone takes years to replenish itself by natural processes, which is more than enough time for the sun to burn the Earth sterile. Or at least, to kill most complex life. In fact, this may have already happened. A GRB has been suggested as one possible cause of the Ordovician extinction 450 million years ago, that eradicated almost 85% of all marine species. Although it’s pretty much impossible to prove. Gamma ray bursts could even be one reason we don’t see life anywhere else in the universe. They might be wiping clean huge chucks of it, on a regular basis. It’s been suggested, that because of GRBs, only 10% of all galaxies might be hospitable to life, similar to us. So, are they going to kill us? Probably not. In a galaxy like ours, there may only be one GRB per millennia. And to harm us, they must be close and directed at us. But since gamma rays travel at the speed of light, we won’t know when it’s headed our way until it arrives. So, there could already be a GRB on its way to kill us all, and we won’t know it, until it hits us, and we’re dead. This video was sponsored by Death from the sky could come around any second. Maybe, even now! So you don’t have any time to waste. Learning to set up a website, portfolio or blog is usually hard and time consuming. Not so with Squarespace though. They let you set up a page with easily understandable tools, very quickly, and without any knowledge of web design. You can use the code “NUTSHELL” to save 10% and support Kurzgesagt. Squarespace have been a great sponsor, so give them some love. You can support us directly at Patreon or get Kurzgesagt merch here: it really helps. Over the next few months, we’d like to make more videos about cataclysmic destructive events, because, honestly, it’s a lot of fun to make these. If you have any ideas about what kind of doomsday scenario you’d like to learn about, let us know in the comments. And if you need to kill a little more time now, here are few related videos. Or maybe… NOW!

100 thoughts on “Death From Space — Gamma-Ray Bursts Explained”

  1. Kurzgesagt – In a Nutshell says:

    There's brand new stuff in the Kurzgesagt Merch Shop. Check it out here:

  2. Flulleo - Liam says:

    Slytheryn reference?

  3. The regular artist says:

    So earth hosted Pokemon, eh? U showed it

  4. SLUGGISH MAGE says:

    I see Pokémon Easter eggs

  5. Avyay Chamantula says:

    5:15 Those are all pokemon. Omanyte, Shellder, Kabuto and Burmy

  6. Adam Kiszka says:

    Kurzgesagt is like: everything is going to kill you, but don't worry!

  7. fred flintstone says:

    What fool would buy an insurance policy for a GRB?

  8. Phoenix says:

    Is that more powerful than a nuke

  9. Letsneversleep 02 says:

    What if a gamma ray burst was shot into a black hole?

  10. *Cloudwyrms * says:


  11. Lukas Lima says:

    5:16 omanyte shelder Kabuto e corsola

  12. Aether Blackstar says:

    Is there a reputable place we can see new info and discoveries about space? I like these videos but many YouTube titles just seem like clickbait. I genuinely just want to learn more about the universe

  13. Down BeatZ says:

    What is the history of ants

  14. Sujal Timalsina says:

    1:36 "ozone layer doesn't block gamma rays….
    It only absorbs UV rays…."
    if you agree….support the statement by ur likes

  15. GrzegorzGear says:

    Americans during red scare were like

  16. The RamenHat says:

    4:42 you are dead. Not big surprise

  17. Vanessa Di Magulangan says:

    My goodness!

  18. Cheese Block says:

    Snipers: I can kill people within a mile away.

    GRB's that killed an entire civilizations from a diffrent galaxy: Pathetic.

  19. jed Rudolph says:

    Kurzgesagt: "Any more detail would require too much mathematics for a YouTube video…"

    MinutePhysics: "Hold my beer…"

    MinutePhysics: "… just for a minute though."

  20. R.J. Paltridge says:

    As your watching this a GRB fries earth DAMN YOU Kurzgesagt! You jinxed me/us!

  21. Charles Houk says:

    Didn’t one of the really dangerous ones almost hit us like 30 years ago?

  22. Blaxkout Studios says:

    Gamma rays can’t kill me if I do it first.

  23. Nicolas Flores says:

    How can a video be this AWESOME

    Or maybe Now !

  24. Josue E Perlin G says:

    Universe is scary sometimes

  25. kattenbroekcom says:

    wow even kurzgesagt like the dark side of the moon from pink floyd 0:55

  26. dj Navi asura says:

    Can you guys make videos about hypersonic aircraft and Antimatter

  27. Melvin Hii says:


  28. Brennen Winterborne says:

    What is it with the Tardis appearing in practically every video?

  29. Benjamin Cushwa says:

    "So, are they going to kill us?

    Probably not."

    In a stroke of irony, a Gamma Ray Burst struck the Earth just as Arthur was watching that segment of the video and died instantly.

    An alternative, and much shorter, version of The Hitchhiker's Guide to the Galaxy, submitted by Ben Cushwa.

    (RIP Douglas Adams.)

  30. TurkeyBoi says:

    5:15 So 450 Million Years Ago we had Pokemon?

  31. Markski gaming says:

    6:00 well ok then
    *walks into baement and starts suplieing

  32. Kinkarter says:

    Epic gamer moment at 5:14

  33. Derek Holcomb says:

    Can’t help thinking you guys are Pokemon fans🤣

  34. Paul Curious says:

    4:50 That sun face though (lmao)

  35. Jackie Chen says:

    here we see virgin walk and the chad stride

  36. 無関係な検索不能 says:

    These give me alot of ideas for mass destruction.

  37. HC Febrian says:

    5:58 that so dark but damn i loled so hard

  38. gabriel sinohui says:

    I felt a great disturbance in the Force, as if millions of voices suddenly cried out in terror and were suddenly silenced.

  39. Ck lemri says:

    5:14 omanyte, shellder, kabuto, corsola

  40. TacklessSix5 says:

    what if it hit right after the video end or even…..right after I click "comment"

  41. Random Guy says:

    Thank for giving me actual anxiety you ruined my day If I die I either go to heaven or nothing you know heaven is nice and all but staying there for infinity I mean for ever whiteout an end I couldn't do that but I don't want to die and go to nothing or something for ever to so what do I do? Nothing i do fucking matters at the end but still everyone including me are acting like it is I just wish I could do whatever I want as long as I'm here because we only get one chance but I can't and all of this is really upsetting me right now I just wanted to learn shit about space I didn't want it to fuck up my soul tho so thanks Kurzgesagt for ruining my day and giving me another big fear to the rest of my life👌🏽

  42. BigMonkey125 says:


    gamma ray bursts: sniping's a good job mate!

  43. Vivek Acharya says:

    That was a clever Harry Potter reference!

  44. Ita Pentony says:

    Cool I always wondered why some black holes have stuff shooting out of them

  45. Jochen says:

    …aaaand we're dead.

    This video was sponsored by…

  46. Dr Phil uwu says:

    I love the pokemon reference

  47. Mr. High school locksmith says:

    "Kill us within an instant"
    Better get started on a webpage

  48. Harth Productions says:

    A ray so powerful it kills atoms.

  49. Bruh moment says:

    Makes video on gamma rays
    Bruce Banner: it's all coming together

  50. LordofBays says:

    2:46 That is the stealthiest Harry Potter reference I have ever seen.

  51. Click Splash Wow says:

    I wonder how big the gamma ray is…

  52. LittleKnight says:


    Kurzgesagt :
    Let's destroy the earth again

  53. HypnoSkales says:

    The mystery of Dr. Stone has finally been solved

  54. Gautiz says:

    there were pokêmon here 450 million years ago?

  55. The Rakai says:

    5:12 lol

    Gotta Catch Em All

  56. Thunder Zeus Show says:

    Can you multiply 1 NONILLION times 678,453?

  57. Thunder Zeus Show says:

    Answer these 2 questions

  58. Jeff Hamm says:

    Mega hammer of dawn

  59. Devon Black says:

    5:31 Is that a Steven Universe reference?

  60. Anthony Ekes says:

    How many Pop Culture references can Kurzgesagt put in one video?

  61. CdHanz钦 says:

    there are two types of peni- gamma ray bursts
    LONG and short ( ͡° ͜ʖ ͡°)

  62. Himanshu Thakur says:

    Why do I feel like, in next 70 years something terrible is going to happen

  63. Julian Sanchez says:


  64. falco830 says:

    12 year old on COD vs GRB: I’ll take your bitch ass to RUST one v one me scrub and I’ll 360 no scope you and your mom with my eyes closed and no perks

  65. sachin hajare says:

    Kabutos ?

  66. sachin hajare says:

    Kabutos ?

  67. Xxgamerxx 35 says:

    I came here for A crisis I was not disappointed

  68. Commetary Momentarily says:

    So how many pokemon are you going to use?
    Kurzgesagt: YES

  69. Phil Sangster says:

    If life on Earth might be snuffed out at any moment, why bother with web design? I would argue we're all better off going outside and enjoying the moments we have, rather than wasting them at the computer.

  70. Daniel Stittums says:

    Love the pokemon reference

  71. Eric weng says:

    what happens if two black hole meet

  72. TreeFiddy says:

    GF: "I don't know… maybe we should wait…"
    Me: Show this video – "So you see, this is the reason why we should have sex today!"

  73. Red says:

    Snipings a good job mate. It's challenging work.

  74. Lenin The Gamer says:

    Don’t worry, guys. The rebels will take it out before any rays can hit earth

  75. Francesco Ceresani says:

    5:30 is that???? a steven universe reference?????

  76. Yonah Sefchovich says:

    Why don’t we just put a big mirror in space. We can “No U” the gamma burst

  77. Hey No says:

    5:26 so that's the reason. Duck face flame princess and yeti guy are extinct

  78. Kaiser says:

    Why the fuck u scaring me

  79. Zane Kreger says:


    Looks like the Ubisoft logo

  80. baka baka says:

    You see, the sun offers us protection as well.

  81. TAN BL says:

    All Black Hole

  82. TAN BL says:

    XBA Power Reduced

  83. J Harbeck says:

    Death star in a nutshell

  84. Justin Banner says:

    Sleep tight children

  85. thunder killer official says:

    5:15 what is that pokemon

  86. InfamousX says:

    The irony is that if a gamma ray does hit us, there will be someone somewhere arguing about how the chances of us being hit by a gamma ray burst are min—————————

  87. A Fro says:

    This reminds me of that scene from star wars when the huge deathstar destroys that planet.

  88. George Nazareth says:

    How two stars can rotate to each other's orbit ? It is not from your video so don't recheck your video

  89. SupaSanic says:

    5:14 oof pokemon, lemme name





  90. AduDOMBA ABLE says:

    5:43 Are they going to kill us?

    Why brother, we will be dead eventually.
    Just grab your beer and cigs and enjoy your life while you can. BE HAPPEEEE

  91. Esse Cara says:


  92. Albino Pineapple says:

    Is there such thing as Existential-Crisis Anonymous? I think I might heading the way.

  93. TheLenki4 says:

    Wait a second, so light cannot escape a black hole but gamma rays can? Like you said it has way more energy than photons so that means that you either need way more energy to escape a black hole or gamma rays aren't affected by gravity at all.

  94. BB Writes says:

    lmao I'm ready


    The answer to 2-1 is legally now "woof"

  96. Dorkfish says:

    Cute pokemon animation.

  97. VarietyTV says:

    Theres no grb progenitor within few thousand light years of earth so no grb is heading our way

  98. ThunderCoookie 23 says:

    OMG gamma Ray bursts killed all the Pokemon??

    And maybe even the Green lantern corps, Pandora, Ego the living planet and most other planets that were supposed to exist!!
    The thought makes me sad

  99. Nick Tastic says:

    So basically space is the Australian outback but infinitely worse

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