Placeholder Image

Subtitles section Play video

  • What if I told you that supernovas

  • aren't the brightest events in the Universe?

  • Gamma-ray bursts are.

  • They shine hundreds of times brighter

  • and only last for several minutes at most.

  • But even a second would be enough

  • for them to mess up all complex life

  • on the planet.

  • Gamma-ray bursts, or GRBs,

  • are the most violent explosions

  • in the Universe.

  • They occur when two neutron stars collide and form a black hole.

  • Or when a black hole swallows a neutron star.

  • Or when a star goes supernova.

  • They're outside the spectrum of visible light.

  • That's why you can't see them with your naked eye.

  • But you'd feel their effect

  • if they were to hit the planet.

  • One of those bursts might have already

  • triggered a mass extinction here on Earth.

  • But that mighty event was 450 million years ago,

  • long before even the first dinosaurs

  • started roaming the planet.

  • If a gamma-ray burst hit us today,

  • we might have a chance to make it out alive.

  • Maybe...

  • Even though the Earth would absorb

  • most of the radiation the blast emitted,

  • the only things that would be in danger down here

  • would be our satellites.

  • Some of them would get knocked offline permanently.

  • You might lose your internet connection, but...

  • it wouldn't take long until

  • most of the malfunctioning satellites were restored.

  • It would change the game completely.

  • The radiation that would rain down on Earth

  • would destroy our ozone layer.

  • Almost all of our plant species would die.

  • There wouldn't be enough of them left to sustain photosynthesis

  • and with that, the amount of oxygen in our atmosphere.

  • Plant-eating animals would starve,

  • and the rest of them would be left to suffocate.

  • Humans could try to save ourselves with oxygen masks, but...

  • even that wouldn't help us last too long.

  • The damage from it would be equivalent to the Earth

  • getting hit by an asteroid.

  • First, it would immediately destroy our atmosphere.

  • Without the atmosphere,

  • we'd be bathing in UV rays,

  • getting severe sunburns,

  • and trying to figure out how to restore the planet's atmosphere

  • before this hostile environment killed us completely.

  • There is good news.

  • Gamma rays have such a short wavelength that,

  • with a bit of luck, the beam could pass relatively close

  • and do no significant damage.

  • But have we ever been so lucky?

  • Nothing would be as devastating

  • as the direct hit of a gamma-ray burst

  • from within our galaxy, the Milky Way.

  • If it makes you feel any better,

  • our satellites would detect the GRB immediately.

  • But what could we do once we found ourselves in the crosshairs

  • of this all-natural galactic phaser?

  • As the burst was approaching the planet,

  • photons would be pulling the ozone layer away

  • and causing chemical reactions on Earth.

  • You'd see a cloud of photochemical smog covering the planet.

  • We'd be blasted with all sorts of cosmic rays.

  • They'd damage our electronics

  • and bring us lethal doses of radiation.

  • You'd witness another wave of mass extinction on Earth.

  • The good thing is that

  • it doesn't look like an event like this

  • is likely happen for another billion years.

  • By that time, we might have figured out

  • how to move the Earth out of the danger zone.

  • But that's a story for another WHAT IF.

What if I told you that supernovas

Subtitles and vocabulary

Operation of videos Adjust the video here to display the subtitles

B1 gamma gamma ray earth burst planet atmosphere

What If a Gamma-Ray Burst Hits the Earth?

  • 2 0
    林宜悉 posted on 2020/04/04
Video vocabulary