Astrophysicist Suzanna Randall explains where the elements in our body come from in this episode of "Starlight" from the European Southern Observatory.
Credit:
ESO
Directed by: Martin Wallner, Luis Calçada, Martin Kornmesser
Hosted by: Suzanna Randall
Written by: Claudia Sciarma, Jonas Enander, Bárbara Ferreira
Editing: Martin Kornmesser
Videography: Angelos Tsaousis
Footage and photos: ESO/M. Kornmesser, ESO/L. Calçada, Natural History Museum, fermilab, Ted Johansson (Fellingsbro folkhögskola, Sweden), Cosmos: Ann Druyan, Carl Sagan, Steven Soter, ESO/Meingast et al.
Music: Johan B. Monell, movetwo, Luis Calçada, videvo
Animations & Infographics: Luis Calçada, Martin Kornmesser, Martin Wallner
Web and technical support: Gurvan Bazin and Raquel Yumi Shida
Scientific consultant: Juan Carlos Muñoz Mateos, Paola Amico
Filming Locations: ESO Supernova
Produced by ESO, the European Southern Observatory
Credit:
ESO
Directed by: Martin Wallner, Luis Calçada, Martin Kornmesser
Hosted by: Suzanna Randall
Written by: Claudia Sciarma, Jonas Enander, Bárbara Ferreira
Editing: Martin Kornmesser
Videography: Angelos Tsaousis
Footage and photos: ESO/M. Kornmesser, ESO/L. Calçada, Natural History Museum, fermilab, Ted Johansson (Fellingsbro folkhögskola, Sweden), Cosmos: Ann Druyan, Carl Sagan, Steven Soter, ESO/Meingast et al.
Music: Johan B. Monell, movetwo, Luis Calçada, videvo
Animations & Infographics: Luis Calçada, Martin Kornmesser, Martin Wallner
Web and technical support: Gurvan Bazin and Raquel Yumi Shida
Scientific consultant: Juan Carlos Muñoz Mateos, Paola Amico
Filming Locations: ESO Supernova
Produced by ESO, the European Southern Observatory
Category
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TechTranscript
00:00We're made of star stuff. We are a way of a cosmos to know itself.
00:07We're made of star stuff.
00:10This term was coined by the astronomer Carl Sagan 50 years ago, and it's since made it into pop culture.
00:17But what does that even mean? And is it true?
00:21Let's see what the universe has to say about this.
00:30Welcome to Chasing Starlights.
00:36I am Susanna Randall, an astronomer at the European Southern Observatory ESO.
00:41And apparently I am made of star stuff.
00:47And so are you. Take a look at your body.
00:50You can see that you're made up of skin, bones, muscle.
00:54If you zoom in with a microscope, you'll find that we're made up of cells.
00:58And if you go even deeper, zoom in even further, you'll see that at the atomic level, we're made up mostly of six elements.
01:05Hydrogen, oxygen, carbon, nitrogen, calcium and phosphorus.
01:11And to tell you where these elements come from, I have to start at the very beginning, at the Big Bang.
01:17In the first few hundred thousand years after the Big Bang, the universe was a dense, hot, gooey plasma.
01:30And what happened after that is basically it expanded and cooled down.
01:35After about 400,000 years, the universe had cooled enough for the first stable atoms to form.
01:41And unsurprisingly, these were the simplest atoms.
01:44So we had some helium as well as traces of other elements.
01:47But mostly the universe was made up of hydrogen, the simplest of all elements, consisting of just one proton and one electron.
01:56So that means my body is made up to 10 percent of something that comes from the Big Bang.
02:05And that makes me a lot older than I care to think about.
02:09But you can't make up something as complex as the human body of just helium and hydrogen.
02:16So where do the other more complex elements that make up our body and the rest of the universe come from?
02:26The first elements in the universe formed diffuse gas clouds called nebulae, where stars form.
02:34In fact, we can still see stars forming in these nebulae today, like in the spectacular image taken by ESO's Vista telescope.
02:42So what happened in the nebula is that there were regions that were a little bit denser than others.
02:48And these regions started accreting more and more mass until they started to collapse in on themselves.
02:55And in the inside of this core, the temperature, pressure and density increased more and more and more
03:01until the temperature was high enough for hydrogen fusion to start and a star was born.
03:09Our own star, the Sun, was created exactly this way 4.5 billion years ago.
03:15And since then, it's been happily fusing away hydrogen to create helium in its core.
03:22But it's not really making any of the other more complex atoms that our body is made of.
03:28For that to happen, we need to wait just a little longer.
03:40When the hydrogen in the core of the star has been used up, things start happening very quickly.
03:46The star enters a new phase of its life called the red giant phase.
03:52The outer envelope of the star expands and cools, hence it becomes a giant,
03:57and the inner part, the core, keeps on contracting until the temperature is high enough for helium to start fusing.
04:04And the helium then creates carbon and oxygen.
04:10So carbon and oxygen were two of the other elements that our body is made up of
04:15and they make up about 84% in mass of our body.
04:20So the majority of the atoms in my body are actually created deep inside stars in these incredibly hot stellar furnaces.
04:33But wait, that means that the carbon and the oxygen are locked inside the core of the star.
04:38How do they get out?
04:40Well, as it turns out, even stars don't live forever.
04:44When the helium runs out in the core of the star,
04:47if the star is not massive enough to fuse heavier elements, then it stops there.
04:52And stars with a similar mass to our Sun, so low-mass stars, can't make elements that are heavier than carbon and oxygen.
04:59Instead, the carbon-oxygen core slowly cools down.
05:03It's this very dense end product of a star called a white dwarf.
05:07And the outer layers are ejected into space.
05:11They form these beautiful arcs, rings, spirals, shells, in other words, star stuff.
05:28On the other hand, stars with more than about eight solar masses continue to fuse elements in their core
05:35and they create heavier and heavier elements, as heavy as iron.
05:41But at some point, even they have to die, and they go out with a bang.
05:45They explode as supernovae.
05:48Fun fact, a supernova occurs roughly every 10 seconds.
05:52So that means that by the time I finish this sentence, a supernova will have gone off somewhere in our universe.
06:00During the supernova explosion, even heavier elements are created.
06:03And these are the really glamorous ones, like gold or platinum.
06:10These are hurled out into space by the explosion, giving us sparkly star stuff.
06:21Ironically, stars need to age and die to form the remaining building blocks of life.
06:28So we have nitrogen, which is important for the synthesis of our DNA.
06:33And we have also calcium and phosphorus, which are important for our bones and teeth.
06:40As it turns out, Carl Sagan was right.
06:43We are literally made up of star stuff.
06:46And the story of stars and their lives is also the story of the elements that make up our body.
06:52We're all part of this grand cosmic cycle.
06:58But before you get too excited, cockroaches are also made up of star stuff.
07:03I don't know about you, but I suddenly feel entirely at one with the universe.
07:11I really hope that you enjoyed this episode of Chasing Starlight.
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