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This Supernova Was Not Supposed to Look Like This · Boring Science

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  Speaker 1: Hello, and welcome to Boring Science to Sleep, a quiet
• 0:04
  Speaker 1: place where science becomes slow, soft and easy to drift through. Tonight,
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  Speaker 1: you're going to gently explore Jupiter, not to learn everything
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  Speaker 1: about this enormous world, but simply to notice it slowly,
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  Speaker 1: calmly and from a little farther away than usual. You
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  Speaker 1: may have always imagined Jupiter as a giant ball of gas,
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  Speaker 1: wrapped in pale clouds with beautiful stripes turning quietly through
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  Speaker 1: the darkness. But there is much more beneath those clouds.
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  Speaker 1: Far below the storms, hydrogen begins to behave in unfamiliar ways.
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  Speaker 1: Deeper still, it can become a strange metallic liquid, moving
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  Speaker 1: through a world of immense pressure, and somewhere farther down,
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  Speaker 1: the centre of Jupiter may not even have the simple
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  Speaker 1: shape that scientists once imagined. But there is nothing you
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  Speaker 1: need to remember tonight. You are safe, there's nothing to do,
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  Speaker 1: and nothing you need to understand completely. If you truly
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  Speaker 1: enjoy these calm journeys through interesting facts about science, you're
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  Speaker 1: welcome to like this video and subscribe, only if it
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  Speaker 1: feels right for you. And when you're ready, let me
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  Speaker 1: know in the comments where you're listening from, and what
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  Speaker 1: time it is right now. It's always a quiet joy
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  Speaker 1: to see how many places and moments gather here together. Now,
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  Speaker 1: Dim the lights, maybe let a fan hum softly in
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  Speaker 1: the background, settle into whatever position feels comfortable, and let
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  Speaker 1: your attention become a little lighter. Tonight, you're simply going
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  Speaker 1: to drift toward Jupiter, and slowly, beneath its familiar clouds,
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  Speaker 1: you may begin to discover that Jupiter is not quite
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  Speaker 1: what you thought. You can begin by imagining that the
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  Speaker 1: night around you has become very still. Far away, beyond
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  Speaker 1: the moon, Beyond the familiar planets, there is a world
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  Speaker 1: turning slowly through the darkness. You do not need to
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  Speaker 1: travel there quickly. There is no destination you need to reach.
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  Speaker 1: You simply let yourself drift toward it. At first, Jupiter
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  Speaker 1: is only a small point of light. From Earth, it
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  Speaker 1: can look almost modest, especially when you remember how enormous
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  Speaker 1: it really is. A quiet light in the night. A
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  Speaker 1: distant planet. And yet, if you could continue moving toward it,
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  Speaker 1: slowly and gently, the little point of light would begin
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  Speaker 1: to grow. The brightness would become a pale sphere. The
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  Speaker 1: sphere would become a world. And eventually, the world would
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  Speaker 1: become so large that it would seem to fill much
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  Speaker 1: of your view. This is Jupiter, the largest planet in
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  Speaker 1: our solar system. It is so large that, if you
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  Speaker 1: could somehow hollow it out, and gently place Earth-sized spaces
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  Speaker 1: inside it, roughly a thousand Earths could fit within its
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  Speaker 1: enormous volume. You do not need to hold on to
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  Speaker 1: that number. Instead, let yourself imagine something smaller and softer.
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  Speaker 1: Imagine Earth as a single grape resting quietly in your hand. Now,
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  Speaker 1: imagine Jupiter beside it. Jupiter would be more like a basketball.
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  Speaker 1: The comparison is not perfect, of course, But it gives
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  Speaker 1: your mind somewhere to rest. A small grape. A large basketball.
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  Speaker 1: And between them, the strange realisation that both are planets.
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  Speaker 1: Both are worlds. Both are moving through the same solar system.
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  Speaker 1: Jupiter is also more massive than all the other planets
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  Speaker 1: in the solar system combined. So, even before you know
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  Speaker 1: what Jupiter is made of, you already know that there
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  Speaker 1: is an enormous amount of material gathered there. But what
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  Speaker 1: kind of material? That question has been waiting for a
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  Speaker 1: very long time. Long before spacecraft travelled through the outer
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  Speaker 1: solar system, people could already see Jupiter moving slowly across
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  Speaker 1: the night sky. Later, telescopes revealed its changing clouds and
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  Speaker 1: broad bands. And then, eventually, spacecraft came close enough to
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  Speaker 1: see it in a completely different way. In the 1970s,
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  Speaker 1: Pioneer 11 approached Jupiter and gave humanity some of its
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  Speaker 1: first close views of the enormous planet. A few years later,
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  Speaker 1: Voyager 1 came through, carrying cameras that showed Jupiter in
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  Speaker 1: much greater detail. The planet became more than a bright
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  Speaker 1: point in the sky. It became a place. A place
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  Speaker 1: with pale bands, darker belts, swirling clouds, enormous storms, and
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  Speaker 1: patterns that seemed almost impossibly large. For a moment, It
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  Speaker 1: might have seemed that seeing Jupiter clearly would finally answer
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  Speaker 1: the old questions. But something curious happened. The better we
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  Speaker 1: could see Jupiter, the more questions appeared. The clouds were beautiful,
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  Speaker 1: but they did not tell us what was beneath them.
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  Speaker 1: The storms were enormous, but they did not reveal where
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  Speaker 1: they came from. The planet looked like a giant ball
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  Speaker 1: of gas, but the word gas became less comfortable the
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  Speaker 1: more deeply scientists thought about it. Because Jupiter does not
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  Speaker 1: have a solid surface like Earth. There is no quiet
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  Speaker 1: shoreline waiting somewhere below the clouds. There is no ground
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  Speaker 1: where you could place your feet. Instead, as you drift downward,
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  Speaker 1: the surrounding material simply becomes denser and denser. The atmosphere
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  Speaker 1: slowly changes. The pressure grows. The temperature rises. And the
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  Speaker 1: familiar idea of a planet begins to soften. You might
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  Speaker 1: imagine yourself floating above Jupiter now, just beneath the distant sunlight,
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  Speaker 1: surrounded by clouds moving in long, gentle bands. Some clouds
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  Speaker 1: are bright, some are darker, some stretch for thousands of kilometres,
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  Speaker 1: and beneath them, deeper layers are waiting. The visible clouds
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  Speaker 1: are only the outermost part of a much larger world.
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  Speaker 1: They are weather, they are movement, they are the surface
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  Speaker 1: appearance of something that does not really have a simple surface.
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  Speaker 1: The great red spot turns somewhere below your field of view,
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  Speaker 1: enormous and slow. A storm larger than Earth, continuing its
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  Speaker 1: long circulation. Tiny particles of ice and droplets move through
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  Speaker 1: the atmosphere. Lightning sometimes flashes deep inside the clouds. Winds
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  Speaker 1: carry material from one region toward another. Everything is moving,
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  Speaker 1: but nothing seems hurried. And beneath all of that motion,
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  Speaker 1: Jupiter continues turning. quietly, patiently, its enormous mass holding everything together,
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  Speaker 1: its gravity reaching outward into space, while at the same
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  Speaker 1: time drawing everything within the planet farther inward. The deeper
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  Speaker 1: you imagine going, the less familiar Jupiter becomes. At first,
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  Speaker 1: you see clouds. Then you begin to imagine deeper layers.
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  Speaker 1: Then pressure. Then heat. then hydrogen behaving in ways that
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  Speaker 1: hydrogen does not behave here on Earth. And eventually, far
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  Speaker 1: below the clouds you can see, there may be a
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  Speaker 1: strange region where the centre of the planet is not
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  Speaker 1: a neat compact ball at all. But you do not
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  Speaker 1: need to go there yet. For now, you can simply
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  Speaker 1: remain above the clouds. You can watch Jupiter turning beneath you.
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  Speaker 1: You can let the pale bands move slowly across your view.
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  Speaker 1: you can remember the tiny grape that represented Earth and
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  Speaker 1: the basketball that represented Jupiter. And perhaps the most interesting
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  Speaker 1: part is that this enormous basketball-shaped world, this planet large
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  Speaker 1: enough to contain roughly a thousand Earths, is still mostly
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  Speaker 1: hidden from us. We have seen its clouds. We have
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  Speaker 1: watched its storms. We have sent spacecraft across the darkness
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  Speaker 1: to look more closely. But the deepest Jupiter has always
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  Speaker 1: been quieter, Hidden beneath layers of pressure and heat, beneath
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  Speaker 1: the clouds and the storms, something waits that may tell
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  Speaker 1: us how this enormous world was born. And to understand that,
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  Speaker 1: you have to let your thoughts drift backward, long before
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  Speaker 1: Jupiter had its familiar bands, before the great red spot
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  Speaker 1: turned beneath the sunlight, before there were spacecraft to photograph it.
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  Speaker 1: Back to a much younger solar system, when the planets
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  Speaker 1: were not yet planets at all, and Jupiter was only
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  Speaker 1: a possibility moving slowly through a cloud of dust, rock, metal,
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  Speaker 1: and gas. For a little while, you can simply rest there,
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  Speaker 1: above the clouds, while that ancient solar system begins to
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  Speaker 1: take shape somewhere far beyond the quietness of the present moment.
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  Speaker 1: Session 2. Two Ways to Build a Giant Planet Purpose
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  Speaker 1: To travel gently backward in time... and explore the two
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  Speaker 1: leading ideas for how Jupiter may have formed, without turning
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  Speaker 1: the explanation into a technical lesson. Scientific focus, the young
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  Speaker 1: solar system, the gradual gathering of rock and metal, gravity-driven growth,
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  Speaker 1: and the alternative possibility of direct gravitational collapse. Approximate length,
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  Speaker 1: 950 words. Long before Jupiter became the enormous world you
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  Speaker 1: were just watching, there was no Jupiter to see. There
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  Speaker 1: were no pale bands moving across the sky, no enormous storms,
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  Speaker 1: no distant spacecraft passing through the darkness. There was only
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  Speaker 1: a young sun, surrounded by a wide, slowly turning disk
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  Speaker 1: of material. You can imagine it as a vast, quiet
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  Speaker 1: construction site, although there were no machines, no walls, and
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  Speaker 1: no hands guiding anything. There was dust, tiny pieces of rock,
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  Speaker 1: small amounts of metal, gas drifting through the darkness, everything
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  Speaker 1: moving around the young sun, carried by gravity and by
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  Speaker 1: the slow motion of the newborn solar system. Some pieces met,
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  Speaker 1: some moved apart, some stayed together, and gradually, Over a
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  Speaker 1: very long time, the small pieces began to gather into
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  Speaker 1: larger ones. You can imagine tiny grains of dust meeting
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  Speaker 1: in the darkness, resting against one another, slowly becoming larger
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  Speaker 1: collections of material. Then larger still, gravity was always there,
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  Speaker 1: quietly waiting. As something became more massive, its gravitational pull
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  Speaker 1: became stronger, allowing it to gather even more material around itself.
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  Speaker 1: This is one of the basic ideas scientists have used
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  Speaker 1: to imagine the birth of Jupiter. In this picture, Jupiter
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  Speaker 1: began with something like a seed, a growing centre made
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  Speaker 1: from heavier materials, perhaps rock and metal, slowly becoming large
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  Speaker 1: enough for its gravity to reach farther into the surrounding disk.
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  Speaker 1: And once that centre became sufficiently massive, it could begin
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  Speaker 1: gathering enormous amounts of gas, hydrogen, helium … the lightest
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  Speaker 1: materials drifting through the young solar system. Little by little,
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  Speaker 1: the growing planet would become larger. Its gravity would reach farther.
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  Speaker 1: More gas would fall inward, and Jupiter would begin to
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  Speaker 1: take the shape of the giant world you know today.
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  Speaker 1: It is a beautiful idea because it begins with something small.
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  Speaker 1: A little gathering of solid material becomes a larger gathering.
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  Speaker 1: The larger gathering becomes a young planetary body. And eventually,
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  Speaker 1: gravity transforms that growing body into one of the largest
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  Speaker 1: planets in the solar system. Scientists often describe this general
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  Speaker 1: idea as core accretion, but you do not need to
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  Speaker 1: hold onto that phrase. It is enough to imagine a
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  Speaker 1: small seed slowly gathering the surrounding world. Yet there is
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  Speaker 1: another possibility, a different way to imagine Jupiter being born.
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  Speaker 1: Instead of beginning with a large solid centre, Imagine a
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  Speaker 1: much larger cloud of gas, a cloud so enormous that
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  Speaker 1: its own gravity begins to pull it inward. At first,
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  Speaker 1: the cloud is spread widely through space, but gravity does
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  Speaker 1: not need to hurry. It simply keeps pulling. The cloud
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  Speaker 1: becomes denser, denser still, and eventually its own weight becomes
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  Speaker 1: enough to make it collapse inward. In this picture, Jupiter
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  Speaker 1: would not need to begin as a small rocky world
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  Speaker 1: that gradually captured its atmosphere. It could begin more like
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  Speaker 1: a great gathering of gas that slowly fell together under
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  Speaker 1: its own gravity. The process has something in common with
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  Speaker 1: the broad idea of how stars form, although Jupiter never
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  Speaker 1: gathered enough mass to become a star. And this possibility
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  Speaker 1: changes the question. If Jupiter began mainly as a collapsing
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  Speaker 1: cloud … Then perhaps there was never a small, compact
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  Speaker 1: centre waiting beneath all that gas. Perhaps the interior began
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  Speaker 1: in a much more complicated way. Perhaps the materials inside
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  Speaker 1: Jupiter were mixed together from the beginning. Two possibilities. Two
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  Speaker 1: very different beginnings. In one, a heavy centre comes first,
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  Speaker 1: and the gas gathers around it. In the other, a
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  Speaker 1: vast cloud gathers itself together, becoming a planet through its
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  Speaker 1: own gravity. And somewhere between those two possibilities lies the
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  Speaker 1: Jupiter that exists today. You can imagine both versions slowly,
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  Speaker 1: without needing to decide which one feels more natural. A
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  Speaker 1: tiny seed gathering everything around it, or a huge cloud
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  Speaker 1: slowly folding inward. Both are quiet processes. Both take enormous
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  Speaker 1: amounts of time, and both lead toward the same enormous planet.
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  Speaker 1: But there is something difficult about testing these ideas. You
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  Speaker 1: cannot simply look at Jupiter and see its history. The
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  Speaker 1: clouds do not carry a label telling you where they
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  Speaker 1: came from. The storms do not reveal whether Jupiter began
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  Speaker 1: with a rocky centre. And the enormous mass of the
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  Speaker 1: planet does not, by itself, tell you how all that
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  Speaker 1: material first gathered together. To understand Jupiter's beginning, scientists need
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  Speaker 1: clues from inside Jupiter itself. And for a very long time,
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  Speaker 1: those clues remained hidden. Then, in the summer of 1994,
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  Speaker 1: something unusual happened. A comet came toward Jupiter. It was
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  Speaker 1: not a spacecraft. It was not a scientific instrument. It
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  Speaker 1: was simply another ancient object moving through the solar system.
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  Speaker 1: But Jupiter's gravity was so strong that the comet could
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  Speaker 1: not remain whole. Slowly, the enormous pull of Jupiter began
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  Speaker 1: to stretch it apart. the comet separated into many pieces,
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  Speaker 1: and suddenly, this distant world had become the setting for
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  Speaker 1: one of the most remarkable natural experiments ever observed. The
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  Speaker 1: fragments were going to fall toward Jupiter, scientists on Earth
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  Speaker 1: prepared to watch, and somewhere in the darkness, a spacecraft
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  Speaker 1: was already on its way. Galileo was travelling toward Jupiter.
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  Speaker 1: It had not been sent there for this particular event.
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  Speaker 1: And yet, by an extraordinary coincidence, it would be in
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  Speaker 1: the right place at the right time. The giant planet
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  Speaker 1: that had hidden its interior for billions of years was
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  Speaker 1: about to be disturbed by a chain of impacts. For
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  Speaker 1: a brief moment, its clouds would brighten, material would rise
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  Speaker 1: above the atmosphere, and the quiet surface we thought we
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  Speaker 1: knew would reveal just a little more of what was
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  Speaker 1: happening underneath. You can let that image remain for a while,
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  Speaker 1: a vast planet turning slowly in darkness. while fragments of
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  Speaker 1: an ancient comet drift toward it, and somewhere nearby, a
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  Speaker 1: small spacecraft waits silently for what Jupiter is about to show.
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  Speaker 1: For a while, you remain with the young solar system,
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  Speaker 1: where Jupiter is still only a growing possibility, gathering material
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  Speaker 1: in the darkness. Then, very slowly, time begins to move
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  Speaker 1: forward again, the Sun becomes familiar, The planets settle into
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  Speaker 1: their long journeys. Jupiter grows into the enormous world you know.
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  Speaker 1: And for billions of years it simply turns there, surrounded
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  Speaker 1: by clouds, keeping most of its interior hidden. From Earth,
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  Speaker 1: you can watch it. You can follow its movement across
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  Speaker 1: the night. You can point a telescope toward those pale
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  Speaker 1: bands and distant storms. But the deepest parts remain out
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  Speaker 1: of sight. Then, in the summer of 1994, Something unusual
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  Speaker 1: came drifting toward Jupiter. It was a comet. Its name
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  Speaker 1: was Shoemaker-Levy 9. It had travelled through the solar system
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  Speaker 1: carrying frozen material and rock, moving quietly through the darkness,
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  Speaker 1: until Jupiter's enormous gravity began to pull it closer. And
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  Speaker 1: Jupiter's gravity was not gentle with the comet. As the
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  Speaker 1: comet approached, the planet's immense gravitational pull stretched it apart.
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  Speaker 1: One object became many. The comet broke into a long
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  Speaker 1: chain of fragments, each piece following a similar path toward Jupiter.
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  Speaker 1: The largest fragments were still a few kilometres across, while
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  Speaker 1: others were much smaller. You can imagine them as a
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  Speaker 1: quiet procession of dark pieces moving through space, all slowly
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  Speaker 1: approaching the same enormous planet. Scientists realised what was about
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  Speaker 1: to happen. The fragments were going to collide with Jupiter.
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  Speaker 1: And because events like this are extremely uncommon, astronomers around
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  Speaker 1: the world prepared to watch. The Hubble Space Telescope was ready.
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  Speaker 1: Telescopes on Earth were ready. But there was a problem.
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  Speaker 1: The fragments were going to strike the far side of Jupiter,
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  Speaker 1: hidden from direct view from Earth. It seemed that the
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  Speaker 1: most interesting part of the event might happen when nobody
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  Speaker 1: could see it. And then there was Galileo. the spacecraft
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  Speaker 1: named after the astronomer who had first observed Jupiter through
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  Speaker 1: a telescope, was already travelling toward the planet. Galileo had
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  Speaker 1: been launched years earlier, long before anyone knew that this
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  Speaker 1: comet would arrive, and somehow its journey had placed it
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  Speaker 1: in a remarkable position. It would have a view that
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  Speaker 1: Earth could not have. So Jupiter continued turning, the fragments
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  Speaker 1: continued falling, and over several days piece after piece disappeared
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  Speaker 1: into the planet's atmosphere. There were 21 major impacts. Each
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  Speaker 1: one briefly disturbed the enormous cloud layers. Some of the
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  Speaker 1: largest fragments released extraordinary amounts of energy. The exact numbers
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  Speaker 1: are difficult to imagine, and you do not need to
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  Speaker 1: imagine them. It is enough to picture a distant world
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  Speaker 1: suddenly marked by flashes and rising clouds of material, while
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  Speaker 1: the planet itself continued turning quietly beneath the event. Hubble
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  Speaker 1: watched the aftermath as Jupiter rotated. Dark marks appeared in
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  Speaker 1: the clouds. Huge plumes of material rose upward. Some of
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  Speaker 1: those traces remained visible for months. And then Galileo approached.
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  Speaker 1: The spacecraft was able to observe the impacts directly, seeing
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  Speaker 1: something that could never be seen from Earth in quite
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  Speaker 1: the same way. For a brief moment, Jupiter had been disturbed.
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  Speaker 1: Material from beneath the visible cloud layer had been carried upward.
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  Speaker 1: The planet had, in a sense, opened a small window
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  Speaker 1: into itself. Not a perfect window, not a clear view
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  Speaker 1: all the way to the centre, but enough to remind
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  Speaker 1: scientists that the beautiful clouds they had been studying for
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  Speaker 1: centuries were were only the outermost part of a much
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  Speaker 1: deeper world. And among Galileo's observations was something especially interesting, water,
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  Speaker 1: a surprisingly large amount of it. That discovery added another
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  Speaker 1: quiet question to the growing collection of questions surrounding Jupiter.
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  Speaker 1: Why was there so much water? What did it tell
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  Speaker 1: us about the material from which Jupiter had formed? And
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  Speaker 1: what might that water mean for everything beneath the clouds?
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  Speaker 1: The answer was not immediately clear, but sometimes a scientific
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  Speaker 1: discovery does not close a door. Sometimes it simply opens
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  Speaker 1: another one. Galileo had helped us look more closely at Jupiter,
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  Speaker 1: and now scientists wanted a spacecraft designed specifically to understand
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  Speaker 1: the planet's interior, its enormous magnetic environment, and the clues
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  Speaker 1: hidden inside its gravity. That spacecraft would be Juno. Juno
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  Speaker 1: was launched in 2011, arrived at Jupiter in 2016, beginning
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  Speaker 1: a new stage in our attempt to understand the giant planet.
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  Speaker 1: You can imagine Juno arriving after all those earlier observations.
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  Speaker 1: Pioneer had shown us Jupiter from close range. Voyager had
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  Speaker 1: shown us its moving clouds and storms. Galileo had entered
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  Speaker 1: the story during the extraordinary comet impacts and had sampled
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  Speaker 1: the atmosphere directly, and now Juno was preparing to look
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  Speaker 1: at Jupiter in another way, not simply through a camera,
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  Speaker 1: not simply by watching its clouds, but by listening to
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  Speaker 1: the planet's gravity, its magnetic field, and the subtle movements
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  Speaker 1: that could reveal what was hidden underneath. The picture was
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  Speaker 1: beginning to change. For a long time, Jupiter had been
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  Speaker 1: easy to describe. A giant planet. A gas giant. A
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  Speaker 1: world covered in clouds. But the closer we looked, the
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  Speaker 1: less complete that description became. The clouds were only the
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  Speaker 1: outer layer, and beneath them the material was becoming denser,
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  Speaker 1: the pressure was becoming stronger, the temperature was rising, water
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  Speaker 1: and ammonia were moving through strange layers of atmosphere, storms
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  Speaker 1: were reaching deeper than their gentle appearance suggested, and somewhere
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  Speaker 1: below all of this Hydrogen itself would begin to behave
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  Speaker 1: in a way that is almost impossible to imagine from
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  Speaker 1: the quiet surface of Earth. So you can remain here
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  Speaker 1: for another moment, floating above Jupiter. The comet has already passed.
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  Speaker 1: The dark marks are slowly fading. Galileo has continued onward.
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  Speaker 1: Juno has arrived. And the planet is turning beneath you
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  Speaker 1: as calmly as before. Nothing about Jupiter looks different from
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  Speaker 1: this distance. The bands still drift around the enormous sphere.
• 23:02
  Speaker 1: The clouds still gather and separate. The storms still move.
• 23:06
  Speaker 1: But now you know that the clouds are not the
• 23:09
  Speaker 1: planet itself. They are only the beginning. And as your
• 23:13
  Speaker 1: attention slowly follows them downward, the bright upper atmosphere begins
• 23:17
  Speaker 1: to fade into deeper layers, where the pressure of the
• 23:20
  Speaker 1: entire world above you begins to make its presence known.
• 23:25
  Speaker 1: The farther down you drift, the warmer it becomes. and
• 23:28
  Speaker 1: the hydrogen, still familiar in name, is about to become
• 23:32
  Speaker 1: something very different. You are still floating above Jupiter. The
• 23:39
  Speaker 1: planet turns slowly beneath you, carrying its pale bands and
• 23:43
  Speaker 1: enormous storms through the darkness. From this distance, the clouds
• 23:48
  Speaker 1: seem almost smooth. They stretch around the planet in long
• 23:52
  Speaker 1: horizontal ribbons, some bright, some darker, moving in different directions.
• 23:58
  Speaker 1: crossing one another, without ever becoming still. But if you
• 24:02
  Speaker 1: drift closer, the smoothness begins to disappear. The clouds are
• 24:06
  Speaker 1: not a painted surface, they are a moving atmosphere, filled
• 24:10
  Speaker 1: with tiny particles, droplets, crystals, gases and currents that rise
• 24:16
  Speaker 1: and fall through one another. And the first thing you
• 24:19
  Speaker 1: notice is how cold the upper atmosphere can become. High
• 24:23
  Speaker 1: above the deeper layers, temperatures can fall far below freezing.
• 24:28
  Speaker 1: The clouds you see from space are made from different
• 24:30
  Speaker 1: materials at different depths, and among them are compounds containing
• 24:35
  Speaker 1: ammonia and other substances that give Jupiter some of its
• 24:39
  Speaker 1: familiar colours. Farther down, water becomes more important. You can
• 24:45
  Speaker 1: imagine the atmosphere not as a single cloud, but as
• 24:48
  Speaker 1: many quiet layers, one resting beneath another. A bright cloud here,
• 24:53
  Speaker 1: a darker region there, a deeper layer here, where water
• 24:56
  Speaker 1: becomes more abundant, and all of it moving slowly around
• 25:00
  Speaker 1: the planet. You do not need to picture a sharp
• 25:03
  Speaker 1: boundary between one layer and another. Jupiter is not built
• 25:07
  Speaker 1: like a stack of perfectly separated sheets. The changes happen gradually.
• 25:12
  Speaker 1: The deeper you drift, the warmer and denser the surrounding
• 25:16
  Speaker 1: material becomes. Water and ammonia can also behave in unusual
• 25:21
  Speaker 1: ways inside these cold, turbulent clouds. In some regions, ammonia
• 25:26
  Speaker 1: can mix with water and help keep the water from
• 25:29
  Speaker 1: freezing as easily as it otherwise might. The result can
• 25:33
  Speaker 1: be something that feels unfamiliar if you are thinking only
• 25:37
  Speaker 1: in terms of Earth. Instead of ordinary rain falling from
• 25:40
  Speaker 1: an ordinary cloud, you can imagine a slow mixture of droplets,
• 25:45
  Speaker 1: ice crystals and slushy material moving through the atmosphere. Some
• 25:50
  Speaker 1: particles fall, some melt, some evaporate. some are carried upward again.
• 25:56
  Speaker 1: The cycle continues quietly inside the enormous atmosphere. And sometimes,
• 26:02
  Speaker 1: these tiny movements become electrical. Water droplets and ice particles
• 26:07
  Speaker 1: move through the clouds, colliding and separating, allowing electrical charges
• 26:12
  Speaker 1: to gather. Eventually, the difference becomes large enough for lightning
• 26:17
  Speaker 1: to occur. You might imagine being somewhere deep inside one
• 26:21
  Speaker 1: of these clouds, surrounded by darkness, with only occasional flashes
• 26:26
  Speaker 1: illuminating the surrounding material. There is no need to imagine
• 26:30
  Speaker 1: the sound as a sudden explosion. Instead, think of the
• 26:34
  Speaker 1: storm from very far away, a faint glow, then darkness again,
• 26:39
  Speaker 1: another distant glow, and beneath all of it, the clouds
• 26:43
  Speaker 1: continue moving. Jupiter's lightning can be extraordinarily powerful, but the
• 26:48
  Speaker 1: process itself begins with very small things. tiny particles moving
• 26:53
  Speaker 1: through a vast atmosphere. This is one of the quiet
• 26:57
  Speaker 1: patterns that repeats throughout Jupiter. Small things, enormous consequences, a droplet,
• 27:04
  Speaker 1: an ice crystal, a little movement, and eventually a flash
• 27:08
  Speaker 1: of light across a storm larger than an entire planet.
• 27:12
  Speaker 1: Far away from you now, the great red spot slowly turns.
• 27:17
  Speaker 1: You have probably seen it before in photographs. a reddish
• 27:21
  Speaker 1: oval surrounded by pale clouds, looking almost like a mark
• 27:25
  Speaker 1: painted onto Jupiter. But it is not a mark. It
• 27:29
  Speaker 1: is a storm, and it is much deeper than it appears.
• 27:33
  Speaker 1: Measurements from the Juno spacecraft have shown that the Great
• 27:37
  Speaker 1: Red Spot extends hundreds of kilometres beneath the visible cloud tops.
• 27:42
  Speaker 1: So when you look at it from above, you are
• 27:45
  Speaker 1: not seeing the whole storm, you are seeing its uppermost expression.
• 27:50
  Speaker 1: The visible colour is only part of the story. Sunlight
• 27:54
  Speaker 1: interacts with chemicals high in the atmosphere, changing the appearance
• 27:58
  Speaker 1: of particles suspended within the storm and contributing to its
• 28:03
  Speaker 1: reddish colour. But the storm itself reaches downward. Far beneath
• 28:07
  Speaker 1: the familiar oval shape, the atmosphere continues, the clouds become denser,
• 28:13
  Speaker 1: the pressure increases, and the gentle movement you can see
• 28:16
  Speaker 1: from space continues into regions you cannot see at all.
• 28:21
  Speaker 1: For a moment, you can imagine following the great red
• 28:24
  Speaker 1: spot downward. You begin above the clouds, where sunlight is
• 28:28
  Speaker 1: still present. Then you move deeper. The light becomes softer.
• 28:33
  Speaker 1: The surrounding atmosphere becomes thicker. The storm is no longer
• 28:37
  Speaker 1: simply something you can look at. It becomes something you
• 28:40
  Speaker 1: are passing through. And this is where Jupiter begins to
• 28:44
  Speaker 1: feel very different from Earth. On Earth, when you look
• 28:47
  Speaker 1: at a planet from space, you can usually identify where
• 28:50
  Speaker 1: the atmosphere ends and the solid world begins. There is
• 28:54
  Speaker 1: a surface beneath the clouds. There is land. There is ocean.
• 28:59
  Speaker 1: There is somewhere to stand. Jupiter offers no such simple boundary.
• 29:03
  Speaker 1: The clouds are only the visible beginning. And compared with
• 29:07
  Speaker 1: the enormous size of the planet, that visible weather layer
• 29:10
  Speaker 1: is surprisingly thin. The uploaded source describes the main ammonia
• 29:15
  Speaker 1: and water cloud region as roughly 50 kilometres deep, an
• 29:20
  Speaker 1: almost delicate layer compared with the enormous world beneath it.
• 29:24
  Speaker 1: So you can imagine Jupiter now as something much larger
• 29:27
  Speaker 1: than the image you see in a telescope, a thin,
• 29:31
  Speaker 1: restless layer of weather wrapped around a vast interior, and
• 29:35
  Speaker 1: you are slowly passing through that layer. The colours begin
• 29:39
  Speaker 1: to fade. The familiar clouds become less distinct. The sunlight
• 29:44
  Speaker 1: becomes more distant. The pressure around you grows stronger. You
• 29:48
  Speaker 1: continue downward, not because you need to reach anything, but
• 29:52
  Speaker 1: simply because the planet itself seems to invite you deeper.
• 29:56
  Speaker 1: Below the clouds, there is no sudden doorway. No line
• 30:00
  Speaker 1: painted across the atmosphere. Only a gradual change. More pressure.
• 30:06
  Speaker 1: More warmth. More density. The hydrogen around you is still
• 30:10
  Speaker 1: a gas in these upper regions. But farther down, the
• 30:14
  Speaker 1: weight of everything above you becomes enormous. The hydrogen is
• 30:18
  Speaker 1: pressed closer and closer together. And slowly, almost imperceptibly, the
• 30:24
  Speaker 1: familiar gas begins to behave differently. You are leaving behind
• 30:28
  Speaker 1: the Jupiter that photographs can show you. The Jupiter of
• 30:32
  Speaker 1: stripes and clouds. The Jupiter of lightning and storms. The
• 30:36
  Speaker 1: Jupiter that appears so simple from a great distance. And
• 30:41
  Speaker 1: beneath it, another Jupiter is waiting. A darker Jupiter. A
• 30:45
  Speaker 1: warmer Jupiter. A denser Jupiter. A world in which the
• 30:50
  Speaker 1: most common element begins to lose its familiar form. As
• 30:54
  Speaker 1: you drift deeper, there is less and less to see.
• 30:57
  Speaker 1: but there is more and more to feel in the
• 31:00
  Speaker 1: changing pressure around you, and somewhere below the clouds, hydrogen
• 31:04
  Speaker 1: is beginning its slow transformation. It is becoming something that,
• 31:09
  Speaker 1: on Earth, you would normally associate with an entirely different world,
• 31:14
  Speaker 1: something liquid. You have already passed through Jupiter's clouds. The
• 31:21
  Speaker 1: bright colours have faded behind you. The distant sunlight is
• 31:25
  Speaker 1: becoming softer. and the familiar patterns of the atmosphere are
• 31:29
  Speaker 1: beginning to disappear. There is no clear moment when you
• 31:32
  Speaker 1: leave the clouds behind. Nothing opens beneath you. There is
• 31:37
  Speaker 1: no doorway. You simply continue downward. And as you descend,
• 31:42
  Speaker 1: something begins to change. The space around you becomes denser.
• 31:46
  Speaker 1: The pressure grows. The temperature rises. There is more material
• 31:51
  Speaker 1: above you now, pressing inward beneath the enormous weight of Jupiter.
• 31:56
  Speaker 1: At first, the change is difficult to notice. The hydrogen
• 32:00
  Speaker 1: surrounding you is still behaving like a gas. It is
• 32:04
  Speaker 1: moving freely, spreading through the space around you. But Jupiter
• 32:09
  Speaker 1: is very large, and all that material above you has weight.
• 32:14
  Speaker 1: The deeper you go, the more that weight becomes part
• 32:17
  Speaker 1: of your surroundings. You might imagine descending into an ocean
• 32:21
  Speaker 1: on Earth. At the surface, the water feels light. A
• 32:25
  Speaker 1: little farther down, the pressure begins to increase. Deeper still,
• 32:30
  Speaker 1: the weight of the water above you becomes noticeable. Now
• 32:34
  Speaker 1: imagine replacing that ocean with an entire planet. Not an
• 32:38
  Speaker 1: ocean covering a planet, but a planet made largely from
• 32:42
  Speaker 1: material that gradually becomes more fluid and more tightly packed
• 32:47
  Speaker 1: as you descend. That is the strange world beneath Jupiter's clouds.
• 32:52
  Speaker 1: The pressure continues to rise. The temperature continues to rise,
• 32:57
  Speaker 1: and hydrogen, which is normally a very light gas, begins
• 33:02
  Speaker 1: to behave differently. It becomes harder and harder to think
• 33:06
  Speaker 1: of the material around you as ordinary gas. The molecules
• 33:11
  Speaker 1: are being pushed closer together, the hydrogen becomes denser, and eventually,
• 33:16
  Speaker 1: in the deeper regions of Jupiter, it behaves as a liquid.
• 33:20
  Speaker 1: This is one of the simplest ways to understand why
• 33:23
  Speaker 1: Jupiter is not quite what it first appears to be.
• 33:26
  Speaker 1: From far away, Jupiter looks like a giant ball of gas.
• 33:31
  Speaker 1: But deep inside, much of that hydrogen is not behaving
• 33:34
  Speaker 1: like the thin gas surrounding you here on Earth. It
• 33:37
  Speaker 1: is compressed into an enormous fluid region. You can imagine
• 33:41
  Speaker 1: a vast ocean, but an ocean without a shoreline, an
• 33:45
  Speaker 1: ocean without waves reaching a beach. an ocean with no
• 33:49
  Speaker 1: surface you could stand upon, just an immense region of
• 33:53
  Speaker 1: hydrogen becoming increasingly dense as it slowly surrounds you. NASA
• 33:58
  Speaker 1: describes Jupiter's interior as becoming progressively denser with depth, with
• 34:03
  Speaker 1: hydrogen transitioning from gas into a liquid-like state under the
• 34:08
  Speaker 1: enormous pressure, and the deeper you drift, the stranger this
• 34:13
  Speaker 1: ocean becomes. On Earth, Hydrogen is usually associated with a
• 34:17
  Speaker 1: very cold environment when you think of it as a liquid.
• 34:21
  Speaker 1: Liquid hydrogen is something that requires extremely low temperatures here.
• 34:26
  Speaker 1: But Jupiter is different. Deep inside this planet, the pressure
• 34:31
  Speaker 1: is so immense that hydrogen can exist as a dense
• 34:34
  Speaker 1: fluid even while the temperature is extraordinarily high. It is
• 34:39
  Speaker 1: one of those quiet contradictions that makes Jupiter so fascinating,
• 34:43
  Speaker 1: cold and hot. gas and liquid, familiar and unfamiliar. The
• 34:49
  Speaker 1: same element you can imagine as an almost weightless gas
• 34:53
  Speaker 1: can become part of an enormous liquid interior. You do
• 34:56
  Speaker 1: not need to picture a dramatic transformation. There is no
• 35:00
  Speaker 1: sudden flash, no sharp boundary. The change happens gradually. The
• 35:05
  Speaker 1: deeper you move, the more crowded the hydrogen becomes. The
• 35:09
  Speaker 1: pressure grows stronger, the temperature rises, and slowly the The
• 35:14
  Speaker 1: material begins to behave less like a gas and more
• 35:17
  Speaker 1: like a fluid. This gradual change is important. There is
• 35:22
  Speaker 1: no ordinary ocean surface inside Jupiter. There is no exact
• 35:26
  Speaker 1: line saying, here the atmosphere ends and here the ocean begins. Instead,
• 35:33
  Speaker 1: Jupiter changes continuously. Gas becomes denser. Dense gas begins to
• 35:39
  Speaker 1: behave more like a fluid. The fluid becomes more compressed.
• 35:43
  Speaker 1: And deeper still, another transformation waits. But for now, you
• 35:49
  Speaker 1: can remain inside this immense liquid region. Imagine yourself floating there.
• 35:55
  Speaker 1: There is no floor beneath you, no ceiling above, no horizon,
• 36:00
  Speaker 1: only darkness and a slowly moving fluid surrounding you in
• 36:05
  Speaker 1: every direction. The hydrogen itself is almost impossible to visualise.
• 36:10
  Speaker 1: You cannot see it as a blue ocean. It has
• 36:13
  Speaker 1: no familiar colour. It is simply matter, packed tightly together
• 36:18
  Speaker 1: beneath the enormous weight of the planet. And yet, in
• 36:21
  Speaker 1: this quiet way, you have reached something extraordinary. You are
• 36:26
  Speaker 1: no longer imagining Jupiter as a ball of gas. You
• 36:29
  Speaker 1: are inside a world where hydrogen has become a liquid.
• 36:33
  Speaker 1: The source material describes this liquid hydrogen region as extending
• 36:37
  Speaker 1: for roughly 20,000 kilometres, an immense depth that is difficult
• 36:42
  Speaker 1: to compare with anything familiar on Earth. You can let
• 36:46
  Speaker 1: that scale become abstract. You do not need to picture
• 36:50
  Speaker 1: the entire distance. Just imagine continuing downward for a very
• 36:54
  Speaker 1: long time, still deeper, still warmer, still denser, and still
• 37:00
  Speaker 1: surrounded by hydrogen. The planet above you is enormous. The
• 37:05
  Speaker 1: planet around you is enormous. And the deeper you travel,
• 37:09
  Speaker 1: the more you begin to realise that Jupiter is not
• 37:13
  Speaker 1: really divided into simple layers, like a fruit with a skin,
• 37:17
  Speaker 1: flesh and seed. Its interior is more gradual than that,
• 37:22
  Speaker 1: more blended, more fluid. The atmosphere becomes a deeper atmosphere.
• 37:28
  Speaker 1: The gas becomes a denser fluid, the fluid becomes something
• 37:32
  Speaker 1: even stranger, and eventually the pressure becomes so strong that
• 37:37
  Speaker 1: the electrons within the hydrogen are able to move much
• 37:39
  Speaker 1: more freely. This is where the word metal begins to
• 37:44
  Speaker 1: enter the story, but not yet. For now, you can
• 37:48
  Speaker 1: simply remain here, drifting inside Jupiter's vast liquid interior. The
• 37:53
  Speaker 1: clouds are far above you, the great red spot is
• 37:56
  Speaker 1: far above you, the sunlight is far above you, and
• 38:00
  Speaker 1: beneath you the planet continues. There is no sound, Only
• 38:05
  Speaker 1: the imagined feeling of slow movement through an immense fluid.
• 38:10
  Speaker 1: The deeper you go, the less Jupiter resembles the planet
• 38:13
  Speaker 1: you saw from space. And perhaps that is the most
• 38:16
  Speaker 1: beautiful part. The planet has not changed. Only your perspective
• 38:20
  Speaker 1: has changed. From far away, it was a striped world
• 38:24
  Speaker 1: of clouds. A little deeper, it became a world of storms.
• 38:28
  Speaker 1: Deeper still, it became an ocean. And now... As you
• 38:32
  Speaker 1: continue downward through that silent ocean, the hydrogen is approaching
• 38:37
  Speaker 1: a state that seems almost impossible to imagine, a state
• 38:40
  Speaker 1: where the lightest element begins to behave like something much heavier,
• 38:45
  Speaker 1: like a metal, and somewhere in that deep, quiet darkness,
• 38:49
  Speaker 1: the invisible currents of Jupiter are beginning to awaken. You
• 38:56
  Speaker 1: are still drifting inside Jupiter. The clouds are now unimaginably
• 39:00
  Speaker 1: far above you. The sunlight has disappeared completely, and there
• 39:04
  Speaker 1: is no longer any familiar sense of sky. Around you,
• 39:08
  Speaker 1: hydrogen fills the darkness. It is dense, warm, and slowly moving,
• 39:15
  Speaker 1: pressed together by the immense weight of everything above. You
• 39:18
  Speaker 1: continue downward. There is no sudden change. The planet does
• 39:22
  Speaker 1: not announce that you have entered a new region. Instead,
• 39:26
  Speaker 1: the pressure simply continues to increase. The temperature continues to rise,
• 39:31
  Speaker 1: and the hydrogen continues to become more tightly packed. If
• 39:35
  Speaker 1: you could somehow observe the tiny particles around you, you
• 39:39
  Speaker 1: would find that they are no longer behaving quite like
• 39:42
  Speaker 1: the hydrogen gas you know. The deeper you travel, the
• 39:46
  Speaker 1: more unusual the material becomes, and eventually, another quiet transformation begins.
• 39:53
  Speaker 1: The hydrogen starts to behave like a metal. This does
• 39:57
  Speaker 1: not mean that it becomes a solid piece of metal.
• 40:00
  Speaker 1: There is no hidden floor of silver or iron waiting
• 40:03
  Speaker 1: beneath you. There is no metallic surface. Instead, the hydrogen
• 40:08
  Speaker 1: remains a fluid. But under the enormous pressure inside Jupiter,
• 40:13
  Speaker 1: the electrons associated with the hydrogen can move much more freely.
• 40:18
  Speaker 1: And that changes everything. You can imagine the difference very gently.
• 40:23
  Speaker 1: In ordinary hydrogen, the electrons are more closely tied to
• 40:27
  Speaker 1: their atoms. But under the immense pressure deep inside Jupiter,
• 40:32
  Speaker 1: the material becomes compressed so strongly that those electrons can
• 40:37
  Speaker 1: move through the surrounding fluid more easily. The result is
• 40:41
  Speaker 1: a strange liquid that can conduct electricity. Scientists call this
• 40:45
  Speaker 1: metallic hydrogen. You only need to remember the name if
• 40:49
  Speaker 1: you want to. The important image is simpler. You are
• 40:53
  Speaker 1: drifting through a vast ocean that can carry electricity. An
• 40:57
  Speaker 1: ocean made not of water, but of hydrogen. A silent,
• 41:01
  Speaker 1: invisible ocean moving deep inside a planet. And this strange
• 41:05
  Speaker 1: property helps explain one of Jupiter's most remarkable features. Its
• 41:10
  Speaker 1: enormous magnetic field. You cannot see a magnetic field directly.
• 41:16
  Speaker 1: There is no glowing shell around Jupiter. no visible boundary.
• 41:21
  Speaker 1: But the magnetic field extends far beyond the clouds, reaching
• 41:25
  Speaker 1: outward into space, and much of the story begins deep inside.
• 41:30
  Speaker 1: Jupiter rotates very quickly. As the planet turns, the conducting
• 41:35
  Speaker 1: fluid inside it also moves. That movement, combined with the
• 41:39
  Speaker 1: electrical conductivity of metallic hydrogen, allows powerful electrical currents to develop.
• 41:46
  Speaker 1: Those currents help generate Jupiter's magnetic field. So something happening
• 41:50
  Speaker 1: in darkness, thousands of kilometres beneath the clouds, reaches outward
• 41:55
  Speaker 1: across an enormous region of space. You can let that
• 41:58
  Speaker 1: connection settle gently in your mind. Deep inside the planet,
• 42:03
  Speaker 1: hydrogen flows. The hydrogen can carry electricity. The planet turns,
• 42:09
  Speaker 1: electrical currents develop, and a magnetic field grows around the world.
• 42:14
  Speaker 1: Nothing dramatic needs to happen. There is no single moment
• 42:17
  Speaker 1: when the magnetic field suddenly appears. It is more like
• 42:21
  Speaker 1: a slow, continuous process that has been taking place for
• 42:25
  Speaker 1: an unimaginably long time. Jupiter turns, the fluid moves, the
• 42:30
  Speaker 1: currents continue, and the invisible magnetic environment remains around the planet.
• 42:37
  Speaker 1: From Earth, we can never see the metallic hydrogen directly.
• 42:41
  Speaker 1: We cannot simply look through Jupiter's clouds and watch the
• 42:45
  Speaker 1: fluid moving inside. Instead, scientists study the effects. They observe
• 42:51
  Speaker 1: Jupiter's magnetic field. They measure tiny changes in its gravity.
• 42:56
  Speaker 1: They study how the spacecraft moves as it passes around
• 42:59
  Speaker 1: the planet. And from these subtle clues, they begin to
• 43:03
  Speaker 1: reconstruct the hidden world below. It is almost like listening
• 43:08
  Speaker 1: to a distant instrument through a closed door. You cannot
• 43:12
  Speaker 1: see what is happening inside, but you can hear the consequences.
• 43:16
  Speaker 1: Juno became especially important for this reason. Its measurements allowed
• 43:21
  Speaker 1: scientists to investigate Jupiter's interior in ways that earlier spacecraft
• 43:26
  Speaker 1: could not. The spacecraft did not need to drill into Jupiter.
• 43:31
  Speaker 1: It did not need to land, it simply travelled around
• 43:33
  Speaker 1: the planet, carefully measuring the subtle effects of Jupiter's enormous
• 43:38
  Speaker 1: mass and magnetic environment. And from those measurements came a
• 43:42
  Speaker 1: surprising realisation. The interior of Jupiter did not seem to
• 43:47
  Speaker 1: match the simplest picture. For a long time, it was
• 43:50
  Speaker 1: easy to imagine a giant planet with a small, dense centre.
• 43:54
  Speaker 1: A compact core. Something solid and heavy hidden beneath the
• 43:59
  Speaker 1: immense layers of hydrogen. But Jupiter was beginning to suggest
• 44:03
  Speaker 1: something different. The deeper scientists looked, the less comfortable the
• 44:07
  Speaker 1: simple picture became. The metallic hydrogen region itself appeared to
• 44:12
  Speaker 1: be part of a much more complicated interior, and somewhere
• 44:16
  Speaker 1: beneath it, the centre of Jupiter might not have a
• 44:19
  Speaker 1: sharp edge. It might not be a neat ball. It
• 44:23
  Speaker 1: might not even be easy to say exactly where the
• 44:26
  Speaker 1: core begins. You can remain here for a moment, drifting
• 44:30
  Speaker 1: through this strange metallic ocean. There is no light, no sound,
• 44:35
  Speaker 1: no visible metal. only an immense fluid moving slowly beneath
• 44:40
  Speaker 1: the weight of an entire planet. Above you are the clouds.
• 44:44
  Speaker 1: Far above them is the sunlight. Around you is hydrogen,
• 44:49
  Speaker 1: but this is no longer ordinary hydrogen. It is dense,
• 44:53
  Speaker 1: it is hot, it can conduct electricity, and its slow
• 44:57
  Speaker 1: movement helps create a magnetic field that stretches far beyond
• 45:01
  Speaker 1: the planet itself. The invisible and the visible are quietly connected.
• 45:06
  Speaker 1: A storm in the clouds. A current deep inside. A
• 45:10
  Speaker 1: magnetic field reaching into space. All part of the same world.
• 45:16
  Speaker 1: And perhaps this is what makes Jupiter so difficult to picture.
• 45:20
  Speaker 1: The farther you travel inward, the less useful ordinary words become. Gas. Liquid. Metal. Core.
• 45:29
  Speaker 1: Each word gives you a small piece of the picture,
• 45:31
  Speaker 1: but none of them describes the entire interior. the material
• 45:35
  Speaker 1: does not arrange itself into perfectly separate layers. The changes
• 45:40
  Speaker 1: are gradual, the boundaries are blurred, and as you drift deeper,
• 45:44
  Speaker 1: the hydrogen begins to mix with heavier material, rock, metal,
• 45:50
  Speaker 1: elements gathered long ago when Jupiter was forming. They may
• 45:53
  Speaker 1: not remain neatly separated, they may be spread through a
• 45:57
  Speaker 1: broad region. The deeper you go, the more the old
• 46:00
  Speaker 1: picture begins to dissolve, and eventually, you reach the quietest
• 46:05
  Speaker 1: mystery of all. The place we call Jupiter's core may
• 46:09
  Speaker 1: not really look like a traditional core. It may be
• 46:12
  Speaker 1: something broader, something more diffuse, something that fades gradually into
• 46:18
  Speaker 1: the metallic hydrogen around it. So you continue drifting downward,
• 46:22
  Speaker 1: the magnetic field continues to surround the planet, the metallic
• 46:26
  Speaker 1: fluid continues to move, and somewhere beneath this vast electric
• 46:31
  Speaker 1: ocean The centre of Jupiter waits in a form that
• 46:34
  Speaker 1: may be far softer, far wider, and far less clearly
• 46:38
  Speaker 1: defined than anyone once imagined. You have drifted through Jupiter's clouds.
• 46:46
  Speaker 1: You have passed into its immense liquid interior. And now,
• 46:50
  Speaker 1: far below the familiar atmosphere, you are approaching the deepest
• 46:54
  Speaker 1: region of the planet. The metallic hydrogen still surrounds you.
• 46:59
  Speaker 1: It is dense, warm. and slowly moving. The pressure is immense.
• 47:04
  Speaker 1: There is no sunlight here. There is no horizon. There
• 47:08
  Speaker 1: is only the quiet interior of a world that has
• 47:11
  Speaker 1: been turning through space for billions of years. And somewhere
• 47:15
  Speaker 1: below you is what we call Jupiter's core. At least,
• 47:19
  Speaker 1: that is the word we use. For a long time,
• 47:23
  Speaker 1: scientists imagined this core as something fairly simple. A compact,
• 47:28
  Speaker 1: dense object, hidden at the very centre of the planet.
• 47:32
  Speaker 1: You could picture it as a small heavy ball, surrounded
• 47:35
  Speaker 1: by layer after layer of hydrogen, rock, metal, heavy material
• 47:42
  Speaker 1: gathered together at the beginning of Jupiter's life. Above it,
• 47:46
  Speaker 1: an enormous ocean of hydrogen. The picture was neat, the
• 47:50
  Speaker 1: centre was solid, the surrounding material was fluid, and somewhere
• 47:54
  Speaker 1: between them there was a clear boundary. It was an
• 47:58
  Speaker 1: understandable picture, but Jupiter did not seem to agree with it.
• 48:02
  Speaker 1: As scientists studied the planet more carefully, especially through measurements
• 48:07
  Speaker 1: made by the Juno spacecraft, the interior began to look
• 48:11
  Speaker 1: less like a series of clean layers and more like
• 48:14
  Speaker 1: something that had been gently stirred together. The core appeared
• 48:18
  Speaker 1: to be much more spread out than expected, not a
• 48:21
  Speaker 1: small sharply defined ball, something broader, something softer at its edges.
• 48:28
  Speaker 1: something that gradually blends into the surrounding material. Scientists sometimes
• 48:33
  Speaker 1: describe this as a fuzzy core. The word sounds almost playful.
• 48:38
  Speaker 1: But beneath the name is a very strange idea. The
• 48:42
  Speaker 1: boundary between the deep metallic hydrogen and the heavier material
• 48:47
  Speaker 1: at Jupiter's centre may not be a simple line. Instead,
• 48:51
  Speaker 1: the materials may overlap. They may gradually become more concentrated
• 48:56
  Speaker 1: as you move inward. rock and metal may be mixed
• 48:59
  Speaker 1: into the surrounding fluid. The centre may be less like
• 49:03
  Speaker 1: a stone hidden inside an ocean, and more like a
• 49:06
  Speaker 1: dense mixture whose ingredients become increasingly concentrated toward the middle.
• 49:11
  Speaker 1: The uploaded source describes this region as extending across roughly
• 49:15
  Speaker 1: half of Jupiter's radius, and compares it to a dense
• 49:19
  Speaker 1: mixture of liquid, rock and metal, without a sharp boundary
• 49:23
  Speaker 1: between the different forms of matter. You can imagine a
• 49:26
  Speaker 1: bowl of thick soup. At first, the image may seem
• 49:30
  Speaker 1: almost too ordinary for something happening inside Jupiter, but imagine
• 49:35
  Speaker 1: that the soup has no surface. Imagine that it fills
• 49:38
  Speaker 1: an enormous part of the planet. Imagine that heavier ingredients
• 49:43
  Speaker 1: slowly become more common as you move toward the centre,
• 49:47
  Speaker 1: while the surrounding fluid gradually changes along with them. There
• 49:52
  Speaker 1: is no clean place where you can point and say,
• 49:55
  Speaker 1: here is the core. Instead, there is a region, a
• 49:59
  Speaker 1: gradual transition, a quiet blending. And this creates another question.
• 50:05
  Speaker 1: Why would Jupiter have such a strange centre? One possibility
• 50:09
  Speaker 1: reaches back to the very beginning of the solar system.
• 50:12
  Speaker 1: Perhaps Jupiter once experienced a collision of extraordinary size. Imagine
• 50:17
  Speaker 1: the young Jupiter, still forming, surrounded by other growing worlds.
• 50:22
  Speaker 1: In the same early solar system, there may have been
• 50:25
  Speaker 1: large rocky bodies moving through the darkness. One hypothesis suggests
• 50:30
  Speaker 1: that a rocky planet, potentially many times more massive than Earth,
• 50:35
  Speaker 1: could have collided with the young Jupiter. You do not
• 50:38
  Speaker 1: need to picture the collision as an explosion in the
• 50:41
  Speaker 1: usual sense. Instead, imagine two enormous young worlds meeting, while
• 50:47
  Speaker 1: everything around them is still unfinished. The energy would be immense.
• 50:52
  Speaker 1: Material from Jupiter's original centre could have been scattered outward.
• 50:56
  Speaker 1: Rock and metal that had once been concentrated in one
• 50:59
  Speaker 1: place could have been mixed into the surrounding hydrogens. The
• 51:03
  Speaker 1: result could have been a diluted, spread-out core, a fuzzy centre.
• 51:08
  Speaker 1: It is an intriguing possibility. It could explain why Jupiter's
• 51:12
  Speaker 1: deepest region looks different from the simple compact core scientists
• 51:16
  Speaker 1: once expected. It might even help explain some aspects of
• 51:20
  Speaker 1: Jupiter's enormous growth. But there is a quiet problem. A
• 51:25
  Speaker 1: possibility is not the same as an answer. Scientists have
• 51:29
  Speaker 1: tried to recreate such enormous collisions using computer simulations. They
• 51:34
  Speaker 1: allow virtual worlds of different sizes and compositions to meet
• 51:38
  Speaker 1: a young Jupiter under different conditions. And in some simulations
• 51:43
  Speaker 1: something interesting happens. The collision can indeed produce a fuzzy core.
• 51:49
  Speaker 1: The heavy material spreads outward. The neat central structure becomes disturbed.
• 51:54
  Speaker 1: For a moment The young Jupiter looks remarkably similar to
• 51:58
  Speaker 1: the Jupiter we think we see today. But then another
• 52:01
  Speaker 1: process begins. The mixed material tends to settle. Gravity continues
• 52:06
  Speaker 1: pulling heavier material inward. Over time, the diffuse core can
• 52:11
  Speaker 1: begin moving toward a more compact arrangement again. The fuzzy
• 52:15
  Speaker 1: centre starts becoming less fuzzy. And this leaves the collision
• 52:19
  Speaker 1: idea with an unanswered question. If a giant impact created
• 52:23
  Speaker 1: the fuzzy core, Why has the core remained diffuse for
• 52:27
  Speaker 1: so long? Why has Jupiter not simply allowed gravity to
• 52:31
  Speaker 1: gather the heavier material back toward the centre? The simulations
• 52:35
  Speaker 1: do not provide a final answer. They give us a possibility,
• 52:39
  Speaker 1: a possible beginning, but not a complete history. And so
• 52:43
  Speaker 1: you remain here, deep inside Jupiter, surrounded by a world
• 52:48
  Speaker 1: that refuses to become simple. Above you is metallic hydrogen.
• 52:52
  Speaker 1: Below you is the diffuse region we call the core,
• 52:56
  Speaker 1: but there is no obvious line separating one from the other.
• 53:00
  Speaker 1: The farther inward you drift, the more concentrated the heavy
• 53:03
  Speaker 1: material becomes. Yet the transition remains gradual. You cannot point
• 53:08
  Speaker 1: to one moment and say that you have crossed into
• 53:11
  Speaker 1: the core. You simply continue inward, and perhaps that is
• 53:15
  Speaker 1: the most beautiful part of the mystery. Jupiter does not
• 53:18
  Speaker 1: seem to care about the neat categories we use to
• 53:21
  Speaker 1: describe it, Gas, liquid, metal, core. These words are useful,
• 53:28
  Speaker 1: but the planet itself is more complicated. Nature does not
• 53:31
  Speaker 1: always draw sharp boundaries. Sometimes one state slowly becomes another.
• 53:37
  Speaker 1: Sometimes materials mix. Sometimes the history of a world remains
• 53:42
  Speaker 1: written in a structure that we can measure, but not
• 53:45
  Speaker 1: completely explain. And perhaps the fuzzy core is exactly that,
• 53:50
  Speaker 1: a memory. a quiet trace of Jupiter's earliest history. Maybe
• 53:54
  Speaker 1: it remembers an ancient collision. Maybe it formed through a
• 53:58
  Speaker 1: more complicated process during Jupiter's birth. Maybe diffuse cores are
• 54:03
  Speaker 1: not unusual at all. Perhaps other giant planets have them too,
• 54:08
  Speaker 1: waiting beneath their own clouds. We simply do not yet know.
• 54:12
  Speaker 1: You have reached the deepest place in this journey, but
• 54:15
  Speaker 1: there is still no final answer waiting beneath you. Only
• 54:19
  Speaker 1: a broad, mysterious centre. A planet that began billions of
• 54:23
  Speaker 1: years ago, still carrying traces of that beginning inside itself.
• 54:28
  Speaker 1: And as you slowly let yourself drift back upward through
• 54:31
  Speaker 1: the metallic hydrogen, one thought can remain behind you in
• 54:35
  Speaker 1: the darkness. We know what Jupiter looks like. We know
• 54:38
  Speaker 1: something about what it is made of. But we still
• 54:41
  Speaker 1: do not completely know how it became this way. And
• 54:45
  Speaker 1: perhaps that unanswered question is what makes the enormous planet
• 54:49
  Speaker 1: above you feel a little more alive, a little more mysterious,
• 54:53
  Speaker 1: and a little more beautiful in the quiet darkness. You
• 55:00
  Speaker 1: have reached the deepest part of Jupiter that this quiet
• 55:03
  Speaker 1: journey can take you. Around you, the darkness is almost complete.
• 55:07
  Speaker 1: The metallic hydrogen continues its slow movement. Farther inward, heavy
• 55:12
  Speaker 1: material becomes increasingly concentrated. and somewhere within that broad, diffuse
• 55:18
  Speaker 1: region is the place we call Jupiter's core. But perhaps
• 55:22
  Speaker 1: now the word core feels a little different. At the
• 55:25
  Speaker 1: beginning of this journey, you might have imagined a small,
• 55:28
  Speaker 1: solid centre, something like a stone hidden inside an enormous planet.
• 55:34
  Speaker 1: A simple centre, a clear boundary, a beginning and an end.
• 55:39
  Speaker 1: Now the picture is softer. The deeper material may be
• 55:42
  Speaker 1: spread across a much larger region. Rock, metal, and surrounding
• 55:46
  Speaker 1: fluid may blend together. There may be no simple line
• 55:50
  Speaker 1: where one layer suddenly becomes another, and the reason for
• 55:54
  Speaker 1: this strange structure remains uncertain. The possibility of an ancient
• 55:58
  Speaker 1: collision is still there, perhaps a very large rocky world
• 56:02
  Speaker 1: once crossed paths with young Jupiter. Perhaps the impact disturbed
• 56:07
  Speaker 1: the heavy material gathering at its centre. Perhaps it scattered
• 56:10
  Speaker 1: that material outward and left Jupiter with the diffuse interior
• 56:14
  Speaker 1: we see today. But the computer simulations leave us with
• 56:17
  Speaker 1: another quiet question. The simulations can create a fuzzy centre
• 56:22
  Speaker 1: after a giant collision. Yet the mixed material tends to
• 56:26
  Speaker 1: settle again. Gravity keeps working. Heavy material slowly moves inward.
• 56:32
  Speaker 1: The diffuse structure begins to become more compact, and so
• 56:36
  Speaker 1: the collision may be part of the story without being
• 56:39
  Speaker 1: the whole story. there may be something about Jupiter's early
• 56:43
  Speaker 1: history that we still do not understand. Perhaps its formation
• 56:48
  Speaker 1: was more complicated than either of the simple pictures we
• 56:51
  Speaker 1: imagined earlier. Perhaps the original material was mixed from the beginning.
• 56:56
  Speaker 1: Perhaps Jupiter grew through processes that we have not yet
• 57:00
  Speaker 1: completely reconstructed. Or perhaps the fuzzy centre is not strange
• 57:05
  Speaker 1: at all. Perhaps this is simply how giant planets work.
• 57:09
  Speaker 1: That possibility is especially interesting, because we have spent most
• 57:13
  Speaker 1: of this journey talking about Jupiter. But Jupiter is not
• 57:17
  Speaker 1: the only giant planet in our solar system. There is Saturn.
• 57:21
  Speaker 1: Farther away, there are the ice giants, Uranus and Neptune.
• 57:27
  Speaker 1: And beyond our solar system, there are enormous numbers of
• 57:30
  Speaker 1: planets orbiting other stars. Some of them are much larger
• 57:33
  Speaker 1: than Earth. Some are close to their stars. Some are
• 57:37
  Speaker 1: extremely cold. Some are called hot Jupiters because they resemble
• 57:42
  Speaker 1: Jupiter in size while orbiting very close to their stars.
• 57:46
  Speaker 1: But we have not yet been able to look inside
• 57:48
  Speaker 1: most of these distant worlds. So we do not know
• 57:51
  Speaker 1: whether Jupiter's diffuse centre is something unusual, or whether it
• 57:56
  Speaker 1: is simply one example of a much more common planetary interior.
• 58:00
  Speaker 1: That is one of the quiet questions Jupiter leaves behind.
• 58:04
  Speaker 1: Is Jupiter strange? Or are we only beginning to discover
• 58:08
  Speaker 1: what giant planets are really like? You can let that
• 58:11
  Speaker 1: question drift through the darkness without trying to answer it,
• 58:15
  Speaker 1: because science does not always move by replacing every mystery
• 58:19
  Speaker 1: with a fact. Sometimes it moves by discovering that an
• 58:22
  Speaker 1: old question was much larger than anyone realised. Pioneer 11
• 58:27
  Speaker 1: gave us one of our first close looks at Jupiter.
• 58:31
  Speaker 1: Voyager 1 showed us the planet as a living world
• 58:34
  Speaker 1: of moving clouds and enormous storms. Galileo gave us a
• 58:39
  Speaker 1: remarkable view during the arrival of Shoemaker-Levy 9 and found
• 58:44
  Speaker 1: unexpected water in the atmosphere. Then Juno arrived, carrying instruments
• 58:49
  Speaker 1: designed to listen more carefully to the hidden structure of
• 58:53
  Speaker 1: the planet. Each spacecraft gave us something new, and each
• 58:57
  Speaker 1: one made Jupiter a little more complicated. That is perhaps
• 59:01
  Speaker 1: the most interesting pattern of all. The first images showed
• 59:05
  Speaker 1: us the clouds. Then we discovered what was beneath the clouds.
• 59:10
  Speaker 1: Then we discovered the liquid hydrogen. Then metallic hydrogen. Then
• 59:15
  Speaker 1: the enormous magnetic field connected to that hidden fluid. Then
• 59:20
  Speaker 1: the strange diffuse centre. And after all of that, one
• 59:24
  Speaker 1: question remains. How did Jupiter become this way? The source
• 59:28
  Speaker 1: material describes this uncertainty directly. Despite the spacecraft and observations
• 59:34
  Speaker 1: that have transformed our understanding, scientists still do not have
• 59:38
  Speaker 1: a clear explanation for how Jupiter acquired its unusual interior.
• 59:44
  Speaker 1: You can slowly begin drifting upward now, not because the
• 59:47
  Speaker 1: journey has to end quickly, simply because you have spent
• 59:51
  Speaker 1: enough time in the deepest darkness. The metallic hydrogen surrounds you.
• 59:56
  Speaker 1: You begin moving through it slowly, The pressure gradually becomes lighter.
• 1:00:01
  Speaker 1: The fluid becomes less dense. Far above you, somewhere beyond
• 1:00:05
  Speaker 1: thousands of kilometres of material, the clouds are waiting. You
• 1:00:09
  Speaker 1: continue upward. The invisible magnetic field remains around the planet.
• 1:00:15
  Speaker 1: The great currents continue moving deep below. The core remains
• 1:00:19
  Speaker 1: where it has always been, holding its unanswered history. And eventually,
• 1:00:25
  Speaker 1: the darkness begins to soften. The upper layers are becoming closer.
• 1:00:30
  Speaker 1: The clouds begin to return, first as a distant suggestion,
• 1:00:34
  Speaker 1: then as faint layers, then as broad bands of pale
• 1:00:38
  Speaker 1: colour moving around the enormous planet. You rise through the
• 1:00:42
  Speaker 1: atmosphere and once again see the familiar Jupiter. The great
• 1:00:46
  Speaker 1: red spot is turning. Lightning is quietly appearing inside distant clouds.
• 1:00:52
  Speaker 1: Water and ammonia are moving through the atmosphere. The planet
• 1:00:56
  Speaker 1: looks almost exactly as it did when you first arrived,
• 1:01:00
  Speaker 1: but now you know that the familiar image is incomplete.
• 1:01:03
  Speaker 1: The clouds are only the outermost expression of a much
• 1:01:07
  Speaker 1: deeper world. Beneath them is an immense fluid interior. Deeper
• 1:01:12
  Speaker 1: still is metallic hydrogen, carrying electrical currents through the darkness.
• 1:01:17
  Speaker 1: And farther down is a strange centre whose boundaries are
• 1:01:20
  Speaker 1: difficult to draw, so perhaps Jupiter was never simply a
• 1:01:24
  Speaker 1: giant ball of gas. Perhaps it was always something more subtle,
• 1:01:29
  Speaker 1: a world of gradual transitions, a world without a simple surface,
• 1:01:34
  Speaker 1: a world where the lightest element can become a dense
• 1:01:36
  Speaker 1: liquid and then a conducting metallic fluid, a world whose
• 1:01:41
  Speaker 1: centre may be less like a solid heart and more
• 1:01:44
  Speaker 1: like a slowly blended memory of its earliest history. And
• 1:01:47
  Speaker 1: perhaps that is why Jupiter remains so fascinating. Not because
• 1:01:52
  Speaker 1: we know everything about it, but because every time we
• 1:01:55
  Speaker 1: look more closely, There is another quiet layer beneath what
• 1:01:58
  Speaker 1: we thought we understood. You are now above the clouds again.
• 1:02:03
  Speaker 1: Jupiter is below you. The planet is turning slowly in
• 1:02:06
  Speaker 1: the darkness. There is nothing left for you to solve tonight.
• 1:02:10
  Speaker 1: You do not need to decide how Jupiter formed. You
• 1:02:14
  Speaker 1: do not need to decide whether the collision happened. You
• 1:02:17
  Speaker 1: do not need to know whether other giant planets carry
• 1:02:20
  Speaker 1: the same strange interior. Those questions can remain there, deep
• 1:02:25
  Speaker 1: inside the planet. waiting for another spacecraft, another observation, another
• 1:02:30
  Speaker 1: generation of scientists. For now, you can simply watch Jupiter turn.
• 1:02:36
  Speaker 1: The clouds continue moving, the storms continue circling, the hidden
• 1:02:41
  Speaker 1: hydrogen continues flowing, and somewhere beneath all of it, the
• 1:02:45
  Speaker 1: mystery remains quiet. Perhaps Jupiter has an answer. Perhaps it
• 1:02:50
  Speaker 1: has several. Perhaps the planet itself is simply carrying the
• 1:02:54
  Speaker 1: history of its birth in a language we are still
• 1:02:57
  Speaker 1: learning how to read. And while Jupiter continues turning through
• 1:03:01
  Speaker 1: the darkness, you can let your attention become lighter, the
• 1:03:05
  Speaker 1: distant clouds becoming softer, the enormous planet slowly becoming smaller
• 1:03:11
  Speaker 1: in your imagination, until it is once again only a
• 1:03:15
  Speaker 1: quiet point of light, drifting peacefully through the night. And so,
• 1:03:22
  Speaker 1: after drifting through Jupiter's clouds, you can slowly let the
• 1:03:26
  Speaker 1: journey become quieter. The enormous planet is still turning beneath you,
• 1:03:31
  Speaker 1: wrapped in its pale bands of cloud, its distant storms
• 1:03:35
  Speaker 1: moving gently through the darkness. The great red spot continues
• 1:03:40
  Speaker 1: its slow rotation. Far below those familiar clouds, liquid hydrogen
• 1:03:45
  Speaker 1: continues to flow. Deeper still, Metallic hydrogen moves through the
• 1:03:50
  Speaker 1: immense pressure of the planet, carrying invisible electrical currents that
• 1:03:54
  Speaker 1: help sustain Jupiter's enormous magnetic field. And somewhere farther down,
• 1:04:00
  Speaker 1: hidden beneath thousands of kilometres of dense material, the fuzzy
• 1:04:04
  Speaker 1: core remains. A strange centre without a perfectly clear boundary,
• 1:04:09
  Speaker 1: perhaps shaped by the earliest moments of Jupiter's formation, perhaps
• 1:04:14
  Speaker 1: altered by an ancient collision. Perhaps formed through a process
• 1:04:18
  Speaker 1: we have not yet completely understood. You do not need
• 1:04:21
  Speaker 1: to solve that mystery tonight. You do not need to
• 1:04:25
  Speaker 1: decide how Jupiter was born. You can simply let the
• 1:04:28
  Speaker 1: questions remain where they are, quietly resting inside the planet.
• 1:04:33
  Speaker 1: Perhaps one day we will understand its beginning. Perhaps another
• 1:04:37
  Speaker 1: spacecraft will discover another clue. Perhaps Jupiter will reveal that
• 1:04:42
  Speaker 1: its interior is even stranger than we imagined. But for now,
• 1:04:47
  Speaker 1: you can leave those questions drifting in the darkness. You
• 1:04:51
  Speaker 1: are safe. There is nothing to do, nothing to remember,
• 1:04:55
  Speaker 1: nothing to figure out. Just listen and drift. Above Jupiter,
• 1:05:01
  Speaker 1: the stars remain still. The planet continues its enormous journey
• 1:05:05
  Speaker 1: around the sun. Its clouds continue moving. Its storms continue turning.
• 1:05:12
  Speaker 1: Its hidden ocean continues flowing beneath the clouds. invisible from
• 1:05:16
  Speaker 1: the distant surface, and the universe continues around it, vast
• 1:05:21
  Speaker 1: and quiet. You can imagine Jupiter becoming smaller now, slowly
• 1:05:26
  Speaker 1: receding into the darkness, its familiar bands becoming softer, its
• 1:05:30
  Speaker 1: great red spot becoming only a tiny warm-coloured mark, and
• 1:05:35
  Speaker 1: eventually the whole planet becoming a distant point beneath the
• 1:05:38
  Speaker 1: endless night. Jupiter will keep turning while you sleep. The
• 1:05:42
  Speaker 1: hydrogen will keep flowing, The magnetic field will continue stretching
• 1:05:47
  Speaker 1: silently through space, and somewhere deep inside that enormous world,
• 1:05:51
  Speaker 1: the mystery will remain, quiet, unhurried, waiting. So you can
• 1:05:57
  Speaker 1: let your breathing become slow, let your body become heavy,
• 1:06:01
  Speaker 1: let your thoughts become softer. There is nothing else you
• 1:06:05
  Speaker 1: need to follow, nothing else you need to understand, just
• 1:06:08
  Speaker 1: the quiet image of a giant planet drifting through space.
• 1:06:13
  Speaker 1: carrying its ancient secrets beneath layers of clouds and darkness.
• 1:06:17
  Speaker 1: And as Jupiter continues turning far away, you can slowly
• 1:06:21
  Speaker 1: drift somewhere quieter still, somewhere beyond the clouds, beyond the storms,
• 1:06:27
  Speaker 1: beyond the metallic ocean, into the soft darkness where there
• 1:06:31
  Speaker 1: is nothing left to discover tonight. Rest well. Jupiter will
• 1:06:35
  Speaker 1: keep turning. The stars will keep shining. and the universe
• 1:06:39
  Speaker 1: will continue carrying everything gently through the darkness while you sleep.