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Flying Through Every Planet In Our Solar System · Boring Science

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  Speaker 1: Tonight, we're going to embark on an impossible journey. A
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  voyage that no human has ever completed, and perhaps never will.
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  We're going to fly through every single planet in our
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  solar system. Not past them, not around them, but straight
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  through their clouds, their storms, their crushing atmospheres, and their
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  mysterious cores. It's a journey that would destroy any spacecraft
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  we've ever built. a trip that defies the laws of
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  physics as we know them. But here, in this quiet moment,
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  we can let our imagination carry us where no rocket
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  ever could. Before we begin this cosmic adventure, feel free
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  to comment your time and location below. It's always amazing
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  to see when and where we're all watching from, or
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  gently drifting off. The visuals are here for you, but
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  there's absolutely no problem if you doze off midway through
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  the video. Feel free to close your eyes, breathe deep,
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  and let your mind soar through the solar system at
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  whatever speed feels right. I would love and encourage you
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  to watch until the end to experience every world we'll visit,
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  but if sleep finds you somewhere between Venus and Saturn,
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  that's perfectly fine too. If you find comfort in these
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  gentle explorations of space, I'd be grateful if you'd consider
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  subscribing and liking this video. It helps the algorithm find
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  more curious minds like us who wonder what it would
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  be like to touch the face of Jupiter or fall
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  through the rings of Saturn. Let's begin our impossible voyage.
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  We're going to start close to home and work our
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  way outward visiting each planet in order from the sun.
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  Some of these worlds will welcome us with gentle breezes.
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  Others will try to crush us, burn us, freeze us,
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  or tear us apart with winds faster than sound. But tonight,
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  we're invincible travelers, immune to heat and cold, pressure and radiation,
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  free to explore every layer of every world in our
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  solar system. Our first destination sits closest to the sun
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  baked in radiation, spinning slowly through space with a surface
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  that tells stories older than life on Earth. This is Mercury,
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  the smallest planet in our solar system, and one of
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  the most extreme places you could ever visit. As we approach,
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  the first thing that strikes you is how utterly alone
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  it looks. No moons orbit this world. No rings grace
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  its equator. Just a grey, cratered sphere that looks remarkably
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  like our own moon, only somehow more ancient, more weathered,
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  more scarred by billions of years of cosmic bombardment. We
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  begin our descent toward the surface, and immediately the temperature
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  starts to climb. The daytime side of Mercury reaches temperatures
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  of 430 degrees Celsius, hot enough to melt lead, hot
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  enough to make zinc boil away into vapour. But Mercury
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  has a secret. Because it rotates so slowly, taking 59
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  Earth days to complete a single spin, and because it
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  has virtually no atmosphere to distribute heat, the night side
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  plunges to minus 180 degrees Celsius. It's a world of
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  impossible extremes, where standing in sunlight would incinerate you while
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  standing in shadow would freeze you solid. As we pass
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  through the thin wisps of what Mercury calls an atmosphere,
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  we barely notice it. This isn't really an atmosphere in
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  any meaningful sense. It's what scientists call an exosphere, so
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  thin that atoms here, potassium, bits of oxygen, rarely collide
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  with each other. There's sodium and hydrogen, all of it
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  captured temporarily from the solar wind before being blown away
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  again into space. The total mass of Mercury's entire atmosphere
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  wouldn't fill a large swimming pool on Earth. We continue downward,
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  approaching the surface, and the landscape becomes clearer. Vast impact
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  basins stretch across the horizon. The Caloris Basin, one of
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  the largest impact craters in the entire solar system, spreads
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  out beneath us like a frozen sea of ancient violence.
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  When the asteroid or comet that created this basin struck
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  Mercury billions of years ago, the impact was so powerful
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  that it sent shockwaves completely through the planet, creating strange
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  rippled terrain on the exact opposite side of the world.
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  Imagine an impact so violent that the entire planet rang
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  like a bell, the surface buckling and cracking from the
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  force transmitted through thousands of kilometres of solid rock. We
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  descend through the surface now, passing through layers of rock
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  and metal that tell the story of Mercury's formation. Unlike Earth,
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  Mercury has an enormous iron core that takes up about
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  three quarters of the planet's diameter. This core is partially
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  molten even today, generating a weak magnetic field that creates
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  a tiny protective bubble around the planet. As we sink
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  deeper into Mercury, the pressure builds and the composition changes,
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  The outer layers are mostly silicate rock, similar to Earth's
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  crust and mantle. But as we approach the core, iron
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  becomes dominant. The core itself is a mystery that scientists
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  are still trying to understand. It's far larger than it
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  should be for a planet this size. One theory suggests
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  that Mercury was once much bigger, perhaps similar in composition
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  to Earth. But a catastrophic collision early in its history
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  stripped away much of its rocky outer layers, leaving behind
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  a world that's mostly metal. Another theory proposes that intense
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  solar radiation in the early solar system vaporized the lighter elements,
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  leaving Mercury with its current metal-rich composition. We pass through
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  the solid outer core and enter the liquid inner regions,
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  where temperatures reach several thousand degrees. Here, convection currents of
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  molten iron generate Mercury's weak magnetic field. about 1% as
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  strong as Earth's, but still enough to deflect some of
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  the solar wind. At the very centre, we might find
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  a solid inner core, similar to Earth's, where the pressure
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  is so immense that iron freezes despite the incredible heat.
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  Emerging from the other side of Mercury, we take one
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  last look at this scorched world. Despite being the closest
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  planet to the Sun, Mercury isn't the hottest planet in
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  the solar system. That distinction belongs to our next destination,
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  a world wrapped in a toxic atmosphere so thick it
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  creates temperatures that exceed even Mercury's sunlit surface. We leave
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  Mercury behind and travel inward toward the Sun, then outward
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  again to our second planet. Venus appears before us like
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  a pale yellow jewel, completely shrouded in clouds. From space,
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  Venus is beautiful. reflecting more sunlight than any other planet,
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  shining brightly enough to cast shadows on Earth. But this
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  beauty is deceiving. Venus is perhaps the most hostile environment
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  in our solar system, a hellscape hidden beneath those innocent-looking clouds.
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  As we approach, we can see the clouds rotating around
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  the planet much faster than the planet itself rotates. Venus
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  has the slowest rotation of any planet. taking 243 Earth
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  days to complete one spin, but the upper atmosphere whips
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  around the planet in just four days, driven by winds
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  reaching 300 kilometers per hour. This phenomenon, called super rotation,
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  is still not fully understood by scientists. We begin our
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  descent into the cloud tops, and immediately we understand why
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  Venus is so difficult to explore. The clouds aren't made
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  of water vapour like Earth's clouds. They're made of sulfuric acid.
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  Concentrated sulfuric acid droplets that would dissolve most materials on contact.
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  These clouds form a layer roughly 20 euring the surface
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  from kilometres thick, completely ob-sc view. No sunlight penetrates these
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  clouds' invisible wavelengths. Any solar panels would be useless here.
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  The cloud deck is illuminated by a dim orange glow,
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  creating a perpetual twilight that never changes. As we descend deeper,
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  the temperature and pressure begin to rise dramatically. The atmosphere
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  of Venus is 96% carbon dioxide, creating the most extreme
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  greenhouse effect known in our solar system. The carbon dioxide
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  traps heat so efficiently that surface temperatures reach 470 degrees Celsius.
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  hot enough to melt lead, hot enough to make some
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  metals glow red-hot. And unlike Mercury, where you could escape
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  the heat by moving into shadow, Venus maintains this temperature
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  day and night, at the equator and at the poles.
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  The thick atmosphere distributes heat so effectively that temperature variation
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  across the entire planet are minimal. We continue sinking through
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  layer after layer of atmosphere. The pressure builds steadily. At
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  10 kilometres above the surface, the pressure is already equal
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  to Earth's sea level. At 5 kilometres the time we
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  reach the surface, the It's doubled. By atmospheric pressure is
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  92 times greater than Earth's, equivalent to being one kilometre
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  deep in Earth's oceans. This pressure is enough to crush
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  most submarines. It's enough to make carbon dioxide behave almost
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  like a liquid, rather than a gas. The surface of
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  Venus finally becomes visible, illuminated by that strange orange glow
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  filtered through 60 kilometres of dense atmosphere. The landscape is
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  unlike anything on Earth. Vast volcanic plains stretch to the horizon,
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  covered in frozen lava flows. Enormous shield volcanoes rise from
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  the surface, some of them larger than any volcano on Earth.
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  Martmons towers 8km above the surrounding plains, and unlike Earth's volcanoes,
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  which are shaped by plate tectonics and erosion, Venus' volcanoes
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  tell a different story. Venus has no plate tectonics as
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  we understand them. The entire surface appears to be a
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  single solid shell. And every few hundred million years, the
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  entire planet seems to resurface itself through massive volcanic eruptions.
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  The current surface is relatively young, perhaps only 500 million
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  years old, suggesting that at some point in Venus' recent past,
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  the entire planet was covered in molten lava. Why this
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  happens is still debated. Perhaps heat builds up beneath the
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  solid crust until the pressure becomes too great and the
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  entire surface breaks apart and melts. Perhaps there are cycles
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  of volcanism we don't yet understand. We sink through the
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  surface now, passing through layers of volcanic rock. The composition
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  is similar to Earth's basalt, rich in iron and magnesium.
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  As we descend, we pass through what might be Venus's
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  crust and mantle. Without plate tectonics, Venus's interior structure is
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  probably simpler than Earth's, without the complex layering created by
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  subduction zones and continental drift. The mantle is likely a
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  thick layer of silicate rock, solid near the surface, but
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  gradually becoming more plastic and flowing at depth. Deeper still,
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  we approach Venus's core, Scientists believe Venus has an iron
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  core similar to Earth's, though probably without the internal structure
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  of separate solid and liquid regions. Venus has no magnetic field,
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  which suggests either that its core is completely solid, completely liquid,
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  or that it rotates too slowly to generate the convection
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  currents necessary for a magnetic dynamo. The core temperature might
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  reach 5000 degrees Celsius, and the pressure could exceed three
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  million times Earth's atmospheric pressure. Emerging on the far side
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  of Venus, we look back at this toxic world with
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  a mixture of fascination and relief. Venus is a cautionary
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  tale of what can happen when a planet's climate spirals
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  out of control. Scientists believe Venus might once have had
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  oceans like Earth, but a runaway greenhouse effect evaporated them
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  billions of years ago leaving behind the inferno we see today.
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  Our next destination is home. Earth, the only planet we
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  know that harbors life, the only world in the universe
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  where you can breathe the air and drink the water
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  and watch clouds drift peacefully across a blue sky. As
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  we approach from space, Earth looks impossibly beautiful. The blue
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  of the oceans, the white of the clouds, the brown
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  and green of the continents, all of it swirling together
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  in patterns that change by the hour. From space, you
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  can see weather systems forming, hurricanes spinning, the Terminator line
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  dividing day from night, sweeping across the surface. We begin
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  our descent, and unlike Mercury and Venus, Earth greets us
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  with a thick but breathable atmosphere. The air is mostly
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  nitrogen and oxygen, with just enough carbon dioxide to keep
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  the planet warm, but not so much that it creates
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  a runaway greenhouse effect. The temperature at the surface averages
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  15 degrees Celsius, perfect for liquid water to exist. As
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  we pass through the upper atmosphere, we feel the thin
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  wisps of air gradually thickening. The mesosphere surrounds us now.
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  Where temperatures drop to their lowest point in Earth's atmosphere,
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  cold enough that water vapour freezes into ice crystals, creating
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  the strange glowing clouds called noctilucent clouds. These clouds are
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  so high and so thin that they're invisible during the day,
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  but at twilight they catch the sun's rays long after sunset,
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  shimmering like silver threads against the darkening sky. We continue
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  downward through the stratosphere, where ozone molecules absorb ultraviolet radiation
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  from the sun, protecting all life below from harmful rays
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  that would otherwise sterilize the surface. This layer is warmer
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  than the mesosphere above it, precisely because of this absorption,
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  creating a temperature inversion that helps keep weather confined to
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  the lower atmosphere. Without this ozone shield, Earth would be
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  as barren as Mars, as lifeless as Venus. The troposphere
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  welcomes us next, the layer where all of Earth's weather happens.
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  Here we pass through towering cumulonimbus clouds that stretch from
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  near the surface all the way to the stratosphere. Lightning
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  flashes within these massive storm systems, transferring energy between the
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  clouds and the ground in brilliant arcs of electricity. The
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  air here is thick and moist, carrying water vapour that
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  will fall as rain, feeding rivers and lakes and forests below.
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  As we approach the surface, The diversity of earth becomes overwhelming.
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  Mountain ranges thrust upward from the crust. The Himalayas still
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  rising as the Indian plate crashes into the Eurasian plate.
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  Deep ocean trenches plunge downward, the Mariana Trench reaching nearly
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  11 kilometres beneath the waves. Deserts spread across continents. Rainforests
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  pulse with life. Ice caps gleam white at the poles.
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  This is a world shaped by plate tectonics, by flowing water,
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  by life itself, all working together to create an ever-changing
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  surface unlike anything else we've seen. We descend through the
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  ocean now, passing through layers of water that grow darker
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  and colder with depth. Sunlight penetrates only the first 200 meters,
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  creating the euphotic zone where photosynthesis can occur. Below this,
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  the Twilight Zone stretches down to a thousand meters, where
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  strange bioluminescent creatures create their own light in the darkness.
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  Deeper still, the Midnight Zone holds mysteries we're only beginning
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  to understand. Creatures adapted to crushing pressures and eternal darkness.
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  The ocean floor spreads beneath us, and we sink through
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  it into Earth's crust. Unlike Venus, Earth's crust is broken
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  into massive plates that slide over the partially molten mantle below.
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  At mid-ocean ridges, new crust forms as magma wells up
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  from below. At subduction zones, old crust slides beneath continental plates,
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  melting and recycling back into the mantle. This constant motion,
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  this endless recycling of Earth's surface, has shaped our planet
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  for billions of years. We pass through the crust and
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  enter the mantle, a layer of hot rock that flows
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  like taffy over geological timescales. The upper mantle is solid
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  but plastic, flowing in vast convection currents that drive plate
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  tectonics at the surface. Deeper in the mantle, the pressure
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  becomes so intense that the crystal structure of minerals changes,
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  becoming denser, packing more efficiently. The lower mantle extends down
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  nearly 3,000 kilometers, gradually increasing in temperature and pressure until
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  we reach the boundary with the core. The outer core
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  greets us with liquid iron and nickel, flowing in massive
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  currents that generate Earth's magnetic field. This magnetic field extends
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  far out into space, creating a protective bubble called the
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  magnetosphere that deflects most of the solar wind. preventing our
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  atmosphere from being stripped away like Mars' atmosphere was billions
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  of years ago. Without this magnetic field, Earth would be uninhabitable,
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  the surface bombarded by radiation. The atmosphere... slowly leaking into space.
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  We sink through the outer core, feeling the temperature rise
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  to nearly 5,000 degrees Celsius, as hot as the surface
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  of the sun. The pressure here is immense, millions of
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  times greater than at the surface. Finally, we reach the
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  inner core, a solid sphere of iron and nickel, kept
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  solid by pressure so intense it overcomes the extreme heat.
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  This inner core rotates slightly faster than the rest of
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  the planet, creating complex interactions with the outer core that
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  scientists are still working to understand. Emerging on the far
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  side of Earth, we take one last look at our
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  home world, the thin blue line of atmosphere. The white
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  swirl of clouds, the deep blue of the oceans, all
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  of it precious beyond measure. Earth is the only place
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  in the universe we know of where you could exist
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  without a spacesuit, where you could breathe deeply and feel
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  rain on your face and watch a sunset paint the
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  sky in colours that no other world can match. But
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  our journey continues outward. Our next destination is the red
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  planet Mars, a world that once might have been as
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  hospitable as Earth but lost its atmosphere billions of years ago,
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  leaving behind a cold desert where ancient riverbeds cut through
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  rust-coloured rock. As we approach Mars, the first thing that
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  strikes you is how small it is. Mars has roughly
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  half the diameter of Earth, giving it only about one-tenth
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  of Earth's mass. From space, it appears distinctly red. coloured
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  by iron oxide dust that covers much of the surface.
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  We begin our descent through Mars' thin atmosphere, and immediately
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  we notice how different it is from Earth's protective blanket
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  of air. The atmospheric pressure at the surface is less
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  than 1% of Earth's sea level pressure, so thin that
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  liquid water cannot exist on the surface. It would either
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  freeze or boil away depending on the temperature. The atmosphere
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  is mostly carbon dioxide, with traces of nitrogen and argon,
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  but there's so little of it that it provides almost
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  no greenhouse warming. Surface temperatures average minus 60 degrees Celsius,
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  though they can rise above freezing at the equator during
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  summer days. As we descend, dust devils swirl across the
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  surface below us, visible even from high altitude. These towering
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  vortices of dust can reach several kilometres high, created by
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  the sun heating the ground unevenly. During certain seasons, dust
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  storms can grow to engulf the entire planet, turning day
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  into twilight and lasting for months. The dust is fine,
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  almost like talcum powder, and it gets into everything, coating
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  every surface, filling every crevice. the surface of Mars spreads
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  out beneath us, a landscape of contrasts. The northern hemisphere
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  is mostly smooth lowland plains, ancient ocean basins that might
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  once have held vast seas of liquid water billions of
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  years ago. The southern hemisphere is heavily cratered highland terrain,
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  similar to the lunar highlands, preserving impacts from the early
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  solar system. The boundary between these regions is one of
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  the most dramatic elevation changes in the solar system, a
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  cliff that stretches around nearly half the planet. We pass
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  over Olympus Mons, the largest volcano in the solar system,
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  a shield volcano so massive it would cover the entire
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  state of Arizona. It rises 21 kilometers above the surrounding plains,
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  nearly two and a half times the height of Mount Everest,
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  with a base 600 kilometers across. The summit holds a
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  caldera 85 kilometres wide, large enough to swallow the city
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  of Paris. This volcano was built over billions of years
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  by countless eruptions, each one adding another layer of lava
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  to the growing mountain. Nearby, the Tharsis region holds three
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  other massive volcanoes, all of them extinct now, all of
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  them testament to a time when Mars was geologically active.
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  But unlike Earth, Mars has no plate tectonics. These volcanoes
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  formed over hot spots in the mantle and stayed in place,
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  growing larger and larger over geological time. On Earth, plate
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  tectonics would have moved the volcanic islands away from their
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  hot spots, creating chains like Hawaii. On Mars, the lack
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  of plate movement allowed single volcanoes to grow to enormous size.
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  We descend toward Valles Marineris, a canyon system so vast
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  it makes Earth's Grand Canyon look like a small scratch.
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  This enormous rift stretches over 4,000 kilometers across the Martian surface,
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  roughly one-fifth of the planet's circumference. In places, it's 7
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  kilometers deep and 200 kilometers wide. If Valles Marineris were
• 25:15
  on Earth, it would stretch from New York to Los Angeles.
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  The canyon was probably formed billions of years ago when
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  the Tharsis region was uplifting, stretching and cracking the crust,
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  like pulling apart a piece of bread dough. We fly
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  along the canyon floor, passing through layers of rock that
• 25:32
  record billions of years of Martian history. Ancient river channels
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  cut through the canyon walls, evidence of a time when
• 25:41
  liquid water flowed across Mars. Some of these channels are enormous,
• 25:46
  suggesting catastrophic floods that dwarfed anything Earth has ever experienced.
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  Scientists believe that underground ice might have melted suddenly, perhaps
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  from volcanic heat, releasing vast quantities of water that carved
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  these massive channels in a matter of days or weeks.
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  We continue our descent, sinking through the surface into Mars' crust.
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  The crust is thicker than Earth's, perhaps 50 kilometers thick
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  on average, composed mostly of volcanic basalt in the lowlands
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  and older, more complex rock in the highlands. Unlike Earth,
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  Mars' crust is a single solid shell, no plates sliding
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  and colliding, no constant recycling of rock. This means the
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  surface preserves features billions of years old, a geological record
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  that goes back to the very beginning of the solar system.
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  As we sink deeper, we pass through the mantles thick
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  layer of silicate rock similar to Earth's mantle, but cooler
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  and more rigid. Mars cooled faster than Earth because of
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  its smaller size, and the mantle no longer flows in
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  the convection currents that drive plate tectonics on Earth. The
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  lack of internal heat also means Mars has no active
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  volcanism anymore, no magnetic field generated by a liquid core.
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  The planet is geologically dead, frozen in time. We approach
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  the core, and here scientists face a mystery. Mars once
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  had a strong magnetic field, evidence preserved in magnetised rocks
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  in the ancient southern highlands. But the field disappeared roughly
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  4 billion years ago. The core is probably made of
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  iron and nickel, like Earth's core, but it must be
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  either completely solid or completely liquid. unable to generate the
• 27:45
  convection currents needed for a magnetic dynamo. Some scientists think
• 27:49
  the core might be partially liquid, but not convecting because
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  it's too cold, or because it contains too much sulfur,
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  which lowers its melting point. The core extends roughly half
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  of Mars' radius, smaller proportionally than Earth's core. The temperature
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  at the center might reach only 2,000 degrees Celsius, much
• 28:12
  cooler than Earth's core. The pressure is also much lower,
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  perhaps only a few hundred thousand times atmospheric pressure, rather
• 28:21
  than the millions of atmospheres at Earth's core. We pass
• 28:25
  through the core and emerge on the far side, leaving
• 28:28
  behind this ancient world that tells the story of what
• 28:32
  happens when a planet loses its atmosphere and its magnetic field.
• 28:37
  Mars is a world of lost potential, a planet that
• 28:41
  might have developed life billions of years ago when it
• 28:44
  had liquid water on its surface, a thicker atmosphere, a
• 28:49
  warmer climate. But without plate tectonics to recycle carbon dioxide,
• 28:55
  without a magnetic field to protect its atmosphere from the
• 28:58
  solar wind, Mars gradually lost its atmosphere to space. The
• 29:04
  water froze or escaped, the climate grew cold. and whatever
• 29:09
  chance Mars had for life slowly disappeared. Our journey continues
• 29:13
  outward now, past the asteroid belt, toward the giant planets
• 29:17
  that dominate the outer solar system. Our next destination is Jupiter,
• 29:24
  a world so massive that all the other planets in
• 29:27
  the solar system could fit inside it with room to spare.
• 29:31
  From a distance, Jupiter appears as a massive globe banded
• 29:35
  with clouds, the great red spot visible as a rust-colored
• 29:40
  oval larger than Earth itself. As we approach Jupiter, the
• 29:44
  sheer scale of this gas giant becomes overwhelming. This isn't
• 29:49
  a planet like the rocky worlds we've visited. This is
• 29:52
  something entirely different, a world with no surface to land on,
• 29:57
  no solid ground to walk across. Jupiter is essentially a
• 30:01
  massive ball of hydrogen and helium, compressed by its own
• 30:06
  gravity into layers that grow stranger and more exotic the
• 30:10
  deeper we descend. The journey to Jupiter takes us past
• 30:14
  its retinue of moons, dozens of them, each a world
• 30:18
  unto itself. We catch glimpses of Io, its surface painted
• 30:23
  in yellows and oranges, the most volcanically active body in
• 30:28
  the entire solar system. We see Europa, wrapped in a
• 30:32
  shell of ice that might hide a liquid ocean beneath.
• 30:36
  An ocean that could potentially harbour life. Ganymede looms large,
• 30:42
  bigger than the planet Mercury, with its own magnetic field.
• 30:47
  Callisto appears ancient and cratered, its surface unchanged for billions
• 30:52
  of years. But we're not stopping at these moons. We're
• 30:56
  heading straight into Jupiter itself, The outer edges of Jupiter's
• 31:00
  atmosphere greet us first, so tenuous that it's hard to
• 31:04
  say exactly where space ends and the planet begins. But
• 31:08
  soon we're enveloped in clouds, and the first thing that
• 31:11
  strikes you is the colour. Bands of white and brown
• 31:15
  and tan stretch horizontally around the planet, each band a
• 31:20
  river of wind flowing at different speeds. These bands are
• 31:25
  organised by latitude, with zones of rising gas appearing bright white,
• 31:31
  and belts of descending gas appearing darker brown and red.
• 31:36
  The winds here are ferocious, reaching speeds of 600 km
• 31:41
  per hour in some regions. These aren't temporary weather systems
• 31:44
  like hurricanes on Earth. These are permanent features of Jupiter's atmosphere,
• 31:49
  driven by the planet's rapid rotation. Jupiter spins once every
• 31:53
  10 hours, faster than any other planet in the solar system,
• 31:57
  And this rapid rotation creates powerful forces that organise the
• 32:01
  atmosphere into these distinct bands. We descend deeper, and the
• 32:06
  Great Red Spot looms before us. A storm system that
• 32:10
  has raged for at least 300 years, possibly much longer.
• 32:16
  This anti-cyclonic storm is so large you could fit two
• 32:20
  or three Earths inside it. The winds at its edges
• 32:24
  reach speeds of 400 km per hour. swirling around a
• 32:28
  high-pressure centre. The reddish colour comes from complex organic molecules
• 32:33
  created by ultraviolet light from the sun. Though the exact
• 32:37
  chemistry is still not fully understood, we plunge into the storm,
• 32:42
  and the turbulence is incredible. Updrafts and downdrafts create violent
• 32:48
  vertical motion. Lightning flashes illuminate the clouds from within, bolts
• 32:53
  of electricity far more powerful than anything on Earth. The
• 32:57
  storm extends deep into Jupiter's atmosphere, perhaps hundreds of kilometres down,
• 33:03
  driven by heat rising from the planet's interior. This is
• 33:07
  weather on a scale that makes Earth's hurricanes look like
• 33:09
  gentle breezes. As we continue our descent, the temperature and
• 33:14
  pressure begin to rise dramatically. The thin upper clouds give
• 33:19
  way to thicker layers. Ammonia ice crystals form the highest clouds,
• 33:24
  creating those white zones we saw from above. Below them,
• 33:29
  ammonium hydrosulfide clouds form a darker layer. Deeper still, water
• 33:35
  clouds form, though we can only infer their existence because
• 33:39
  we can't see this deep into Jupiter's atmosphere from the outside.
• 33:43
  The pressure builds steadily as we sink. At 100 kilometres
• 33:48
  below the cloud tops, the atmospheric pressure equals Earth's sea
• 33:53
  level pressure. At 200 kilometres, it's doubled. The temperature rises too,
• 33:59
  reaching comfortable room temperature at certain depths, creating a layer
• 34:04
  where the pressure and temperature would theoretically allow humans to exist,
• 34:09
  if only there were something to stand on. But there isn't.
• 34:13
  There's just more and more atmosphere pressing down from above.
• 34:18
  We continue sinking, and around 1,000 kilometers deep, something remarkable happens.
• 34:26
  The pressure becomes so intense that hydrogen begins to behave differently.
• 34:31
  Under normal conditions, hydrogen is a gas, with individual molecules
• 34:36
  bouncing around freely. But under extreme pressure, those molecules are
• 34:42
  forced closer and closer together until they start to form
• 34:45
  a liquid. We're entering Jupiter's liquid hydrogen ocean, a sea
• 34:50
  with no surface, no waves, just an endless expanse of
• 34:54
  liquid hydrogen that extends thousands of kilometres down. The transition
• 35:00
  from gas to liquid isn't sharp like water boiling on
• 35:03
  a stove. Instead, it's gradual, a continuous change as the
• 35:09
  pressure increases, the density slowly increases, the viscosity changes, and
• 35:15
  eventually you're swimming through liquid rather than flying through gas.
• 35:21
  This liquid hydrogen ocean is one of the strangest features
• 35:25
  of Jupiter, a sea that exists nowhere on Earth, because
• 35:30
  we can't create the pressures necessary to liquefy hydrogen under
• 35:34
  these conditions. We sink deeper still, thousands of kilometers into
• 35:39
  Jupiter's interior, and the pressure continues to build. At around 20,000
• 35:45
  kilometers deep, we reach a pressure of 2 million Earth atmospheres. Here,
• 35:52
  something even stranger occurs. The pressure is so immense that
• 35:56
  hydrogen is forced into a state that doesn't exist anywhere
• 36:00
  else in the solar system except in the cores of
• 36:03
  the other giant planets. The electrons are stripped away from
• 36:07
  the hydrogen atoms, creating a fluid that conducts electricity like
• 36:11
  a metal. This is metallic hydrogen, a substance that scientists
• 36:17
  have tried to create in laboratories on Earth. but have
• 36:21
  only managed to produce for microseconds before it explodes. This
• 36:26
  metallic hydrogen ocean extends for thousands of kilometers, and it's
• 36:31
  here that Jupiter's powerful magnetic field is generated. Electric currents
• 36:37
  flowing through this metallic hydrogen create a magnetic field 14
• 36:42
  times stronger than Earth's, extending millions of kilometers into space.
• 36:47
  This magnetic field traps charged particles from the solar wind
• 36:51
  creating radiation belts so intense they would kill an unprotected
• 36:56
  human in minutes. It's this magnetic field that creates Jupiter's
• 37:01
  spectacular auroras, glowing ribbons of light at the poles far
• 37:06
  more powerful than Earth's northern and southern lights. We continue
• 37:11
  our descent through the metallic hydrogen, feeling the temperature climb
• 37:16
  to 10,000 degrees Celsius, as hot as the surface of
• 37:20
  the sun. The pressure here exceeds 40 million Earth atmospheres,
• 37:25
  crushing beyond anything we can truly comprehend. And yet we
• 37:29
  continue deeper, toward Jupiter's core, the mysterious heart of this
• 37:34
  giant world. Scientists have debated for decades about what lies
• 37:39
  at Jupiter's centre. Early models suggested a small rocky core,
• 37:44
  perhaps 10 to 15 times Earth's mass, made of heavy
• 37:48
  elements that sank to the centre during Jupiter's formation. More
• 37:52
  recent data from the Juno spacecraft suggests something more complex,
• 37:57
  possibly a diluted core where rock and metallic hydrogen are
• 38:01
  mixed together, or perhaps no distinct core at all, just
• 38:05
  a gradual transition to denser materials. As we approach the centre,
• 38:11
  we might find a region enriched in heavy elements like iron,
• 38:14
  silicon and oxygen, but not formed into a solid ball
• 38:18
  the way Earth's core is. The temperature here could reach 30,000
• 38:23
  degrees Celsius, and the pressure might exceed 50 million Earth atmospheres.
• 38:29
  The conditions are so extreme that our understanding of how
• 38:33
  matter behaves breaks down. We're in a realm where quantum
• 38:37
  effects become important, where the normal rules of chemistry and
• 38:42
  physics need to be reconsidered. Emerging from the other side
• 38:46
  of Jupiter, we look back at this magnificent giant, A
• 38:50
  world that contains more mass than all the other planets combined.
• 38:55
  A world whose gravity shaped the entire solar system. Jupiter's
• 39:00
  powerful gravitational field has acted as both protector and destroyer.
• 39:06
  It has flung countless comets and asteroids out of the
• 39:08
  solar system, or crashed them into the sun, protecting the
• 39:13
  inner rocky planets from bombardment. but it has also prevented
• 39:17
  the formation of another planet in the asteroid belt. Its
• 39:21
  gravity stirring up the region so much that planetesimals could
• 39:25
  never coalesce into a larger world. We leave Jupiter behind
• 39:29
  and continue outward to Saturn, the jewelled planet, the crown
• 39:34
  of the solar system. From a distance, Saturn appears serene,
• 39:39
  wrapped in its famous rings that extend hundreds of thousands
• 39:42
  of kilometres, but are less than a kilometre thick in
• 39:45
  most places. These rings aren't solid. They're made of countless
• 39:51
  individual chunks of ice and rock, ranging from particles smaller
• 39:56
  than a grain of sand to boulders the size of houses,
• 40:00
  all orbiting Saturn in a flat disk. As we approach,
• 40:04
  the rings become more detailed. We can see gaps in
• 40:07
  the rings, divisions carved by the gravitational influence of Saturn's
• 40:12
  many moons. The Cassini Division is the largest gap, a
• 40:17
  region 4,000 kilometers wide, where the rings thin out dramatically.
• 40:22
  The Enki Gap is narrower, only 300 kilometers wide, kept
• 40:28
  clear by a small moon called Pan that orbits within
• 40:32
  the gap, sweeping up particles like a cosmic vacuum cleaner.
• 40:37
  We pass through the rings, and the experience is otherworldly.
• 40:42
  Chunks of ice tumble around us, each one reflecting sunlight,
• 40:47
  creating a glittering field of frozen debris. Some pieces are
• 40:52
  pure ice, white as snow. Others are dirty ice, stained
• 40:58
  by rocky impurities. The rings aren't uniform. They're divided into
• 41:02
  thousands of narrow ringlets, each one slightly different in composition
• 41:07
  and density, creating a structure as complex as a vinyl
• 41:12
  record when viewed up close. But we're not here to
• 41:15
  explore the rings. We're diving into Saturn itself, and as
• 41:20
  we approach the cloud tops, we see a world similar
• 41:23
  to Jupiter, but somehow more subdued, more elegant. The bands
• 41:28
  are there, the zones and belts organised by latitude, but
• 41:33
  they're hazier, less distinct. The colours are more muted, pale
• 41:39
  yellows and creams and tans. There's no great red spot
• 41:43
  on Saturn. though there are occasional massive storms that erupt
• 41:47
  and encircle the entire planet in bands of white clouds.
• 41:51
  We descend through the upper atmosphere, and immediately we notice
• 41:55
  how cold it is. Saturn is nearly twice as far
• 41:59
  from the Sun as Jupiter, and it receives only about
• 42:02
  one-fourth as much sunlight. The cloud tops are frigid, minus
• 42:08
  140 degrees Celsius. The atmosphere is similar to Jupiter's, mostly
• 42:13
  hydrogen and helium with traces of methane and ammonia, but
• 42:17
  the colder temperatures mean the clouds form at different altitudes,
• 42:21
  creating Saturn's distinctive hazy appearance. As we sink deeper, the
• 42:28
  pattern is familiar from Jupiter. The pressure and temperature rise.
• 42:33
  Ammonia ice clouds give way to ammonium hydrosulfide clouds and
• 42:38
  then water ice clouds. The winds are powerful here too.
• 42:43
  reaching 1800 km per hour at the equator, even faster
• 42:47
  than Jupiter's winds. These super-rotating winds create a hexagonal pattern
• 42:54
  at Saturn's north pole, a bizarre geometric formation that has
• 42:59
  existed for decades. Each side of the hexagon is wider
• 43:04
  than Earth's diameter, and the mechanism that creates and maintains
• 43:08
  this shape is still not fully understood. We continue our
• 43:12
  descent through Saturn's atmosphere, and around 1,000 kilometers deep, we
• 43:18
  enter the liquid hydrogen ocean, just as we did on Jupiter.
• 43:23
  The transition is gradual, the gas becoming denser and denser,
• 43:28
  until it's clearly a liquid. We sink through thousands of
• 43:33
  kilometers of this liquid hydrogen, the pressure building, the temperature rising.
• 43:39
  At around 30,000 kilometers deep, we reach the metallic hydrogen layer,
• 43:45
  where hydrogen conducts electricity and generates Saturn's magnetic field. Saturn's
• 43:52
  magnetic field is weaker than Jupiter's, only about 20 times
• 43:56
  stronger than Earth's field, but it's still powerful enough to
• 44:01
  create magnificent auroras at the poles. These auroras are visible
• 44:06
  in ultraviolet light, glowing ribbons that dance across the polar regions.
• 44:12
  energised by particles from the solar wind and from Saturn's
• 44:15
  moon Enceladus, which spews water vapour into space from geysers
• 44:21
  at its south pole. We continue through the metallic hydrogen,
• 44:26
  feeling the temperature climb to 15,000 degrees Celsius. The pressure
• 44:31
  here exceeds 60 million Earth atmospheres. And somewhere deep within Saturn,
• 44:37
  perhaps at the very centre, there might be a core
• 44:41
  of heavy elements, rock and metal compressed to unimaginable densities.
• 44:47
  Or perhaps, like Jupiter, Saturn has a diluted core, a
• 44:53
  fuzzy boundary, where heavy elements gradually give way to metallic hydrogen.
• 44:58
  The core, if it exists as a distinct entity, might
• 45:02
  be 10 to 20 times Earth's mass, but spread over
• 45:06
  a region larger than Earth itself, The temperature at the
• 45:09
  centre could reach 20,000 degrees Celsius, and the pressure might
• 45:13
  approach 80 million Earth atmospheres. We're at the limit of
• 45:18
  what our current physics can reliably predict. The behaviour of
• 45:22
  matter under these conditions is still an active area of research,
• 45:25
  with scientists using powerful computers to simulate the quantum interactions
• 45:30
  of atoms under extreme pressure and temperature. Emerging from Saturn,
• 45:35
  we take a moment to appreciate what we've just experienced.
• 45:39
  These gas giants, Jupiter and Saturn, represent a different class
• 45:44
  of planet entirely from the rocky worlds of the inner
• 45:47
  solar system. They're mostly hydrogen and helium, the same elements
• 45:52
  that make up the sun, and in a sense they're
• 45:55
  failed stars. Worlds that didn't quite gather enough mass to
• 45:59
  ignite nuclear fusion in their cores. If Jupiter had been
• 46:03
  about 80 times more massive, it would have become a star.
• 46:08
  and our solar system would have been a binary star
• 46:11
  system with two suns. But our journey isn't over. We
• 46:15
  continue outward to the ice giants Uranus and Neptune, worlds
• 46:19
  that are smaller than Jupiter and Saturn, but still enormous
• 46:22
  compared to Earth. These planets have a different composition, with
• 46:27
  much more water, methane and ammonia mixed with their hydrogen
• 46:31
  and helium. They're colder, stranger. and in some ways even
• 46:36
  more mysterious than the gas giants we've just visited. Uranus
• 46:40
  appears before us, a pale blue-green sphere tipped on its side.
• 46:46
  Unlike every other planet, which spins roughly upright, Uranus rotates
• 46:50
  on its side, its axis tilted 98 degrees. This means
• 46:55
  that for part of its 84-year orbit around the Sun,
• 46:59
  one pole points directly at the Sun, while the other
• 47:02
  pole faces eternal darkness. Then, 42 years later, the situation reverses.
• 47:11
  This strange tilt was probably caused by a massive collision
• 47:15
  early in Uranus' history, an impact so violent it knocked
• 47:19
  the entire planet over. As we approach, we see that
• 47:24
  Uranus is remarkably bland compared to Jupiter and Saturn. There
• 47:29
  are few visible cloud features, just a smooth blue-green disc.
• 47:35
  The colour comes from methane in the upper atmosphere, which
• 47:38
  absorbs red light and reflects blue and green. The lack
• 47:43
  of visible features doesn't mean Uranus is inactive. It just
• 47:48
  means that whatever weather systems exist are hidden beneath thick
• 47:53
  layers of haze. We begin our descent and the upper
• 47:58
  atmosphere is incredibly cold, minus 220 degrees Celsius, the coldest
• 48:05
  planetary atmosphere in the solar system. The atmosphere is mostly
• 48:09
  hydrogen and helium, but with a much higher proportion of
• 48:13
  methane than Jupiter or Saturn. As we descend, the temperature
• 48:18
  slowly rises, but Uranus generates very little internal heat compared
• 48:23
  to the other giant planets. While Jupiter and Saturn radiate
• 48:27
  more heat than they receive from the Sun, Uranus radiates
• 48:31
  almost nothing, making it colder than it should be at
• 48:35
  this distance from the Sun. We pass through the relatively
• 48:39
  thin atmospheric layer, only a few thousand kilometers deep, and
• 48:44
  enter a realm that scientists call the mantle, though it's
• 48:48
  nothing like Earth's rocky mantle. This is a hot, dense
• 48:53
  fluid made of water, methane, and ammonia, compressed to enormous pressures.
• 49:00
  Under these conditions, water doesn't behave like the liquid we're
• 49:03
  familiar with. It's a superionic ice, a bizarre state where
• 49:08
  oxygen atoms are locked in a solid crystal lattice, while
• 49:13
  hydrogen ions flow freely through that lattice, conducting electricity. This
• 49:18
  superionic iso extends for thousands of kilometres, and it's thought
• 49:24
  to be the source of Uranus's magnetic field. But that
• 49:28
  magnetic field is strange, tilted 60 degrees from the planet's
• 49:33
  rotation axis, and offset from the centre. The field wobbles
• 49:39
  wildly as Uranus rotates, creating a corkscrew shape that's unlike
• 49:43
  any other planetary magnetic field in the solar system. We
• 49:47
  sink deeper through this exotic ocean, passing through regions where
• 49:51
  the pressure exceeds 2 million Earth atmospheres and the temperature
• 49:55
  climbs to 5,000 degrees Celsius. And at the very centre
• 49:59
  of Uranus, there might be a small rocky core, perhaps
• 50:03
  half an Earth mass of iron and silicate rock. compressed
• 50:07
  to incredible densities. Or perhaps there's no distinct core at all,
• 50:13
  just a gradual transition to denser materials. Emerging from Uranus,
• 50:18
  we continue outward to our final destination, Neptune, the most
• 50:22
  distant planet in our solar system since Pluto's reclassification. Neptune
• 50:28
  appears as a deeper, richer blue than Uranus, coloured by methane,
• 50:33
  but somehow more vibrant, more alive. As we approach, we
• 50:38
  immediately see that Neptune is far more active than Uranus,
• 50:42
  despite being farther from the Sun and receiving even less sunlight.
• 50:47
  Great dark spots appear in Neptune's atmosphere, massive storm systems
• 50:51
  similar to Jupiter's Great Red Spot. White clouds of methane
• 50:55
  ice float high above the main cloud deck, casting shadows
• 50:59
  on the layers below. Wind speeds here are the fastest
• 51:03
  in the solar system, reaching 2,000 km per hour, faster
• 51:07
  than the speed of sound on Earth. How Neptune generates
• 51:12
  enough energy to drive these incredible winds is still a mystery,
• 51:16
  because like Uranus, Neptune should be too cold and too
• 51:20
  far from the Sun to have such active weather. We
• 51:24
  descend into Neptune's atmosphere, and the structure is similar to Uranus.
• 51:28
  A relatively thin atmospheric layer gives way to a deep
• 51:32
  ocean of superionic ice, a mixture of water, methane, and
• 51:37
  ammonia compressed to exotic states. Neptune's magnetic field is also
• 51:43
  tilted and offset, creating a complex field structure that wobbles
• 51:48
  as the planet rotates. And deep within Neptune, there might
• 51:53
  be a rocky core, perhaps slightly larger than Uranus's core,
• 51:58
  compressed to unimaginable densities by the weight of the entire
• 52:02
  planet pressing down from above. As we emerge from Neptune
• 52:07
  and look back at the eight worlds we've visited, the
• 52:10
  diversity is staggering. From the scorched surface of Mercury to
• 52:16
  the frozen depths of Neptune, from the toxic clouds of
• 52:19
  Venus to the metallic hydrogen oceans of Jupiter, each planet
• 52:24
  tells a unique story about how worlds form and evolve.
• 52:29
  Our solar system is a laboratory of planetary science. showing
• 52:33
  us the full range of possibilities that exist when gas
• 52:37
  and dust collapse under gravity to form new worlds. But
• 52:41
  there's something humbling about this journey too. We've travelled through
• 52:45
  planets that would instantly destroy any spacecraft we could build.
• 52:49
  We've experienced temperatures that would vaporise steel, and pressures that
• 52:53
  would crush diamonds. We've seen storms that have raged for centuries,
• 52:59
  and magnetic fields that could scramble electronics from millions of
• 53:03
  kilometers away. The solar system is beautiful, but it's also hostile,
• 53:09
  a reminder that Earth's gentle climate and breathable atmosphere are
• 53:14
  precious beyond measure. As we drift away from Neptune, the
• 53:18
  solar system spreads out before us like a cosmic map,
• 53:22
  each planet now a memory etched into our consciousness. The
• 53:26
  journey we've taken tonight exists only in imagination, yet it
• 53:30
  reveals truths about our cosmic neighbourhood that telescopes and spacecraft
• 53:36
  have spent decades uncovering. We've touched worlds that no human
• 53:41
  hand will ever reach, descended through atmospheres that would dissolve
• 53:45
  our bodies in seconds, and witnessed the alien beauty of
• 53:49
  planets that challenge everything we thought we knew about how
• 53:53
  worlds should behave. Think about what we've experienced together. Mercury
• 53:58
  taught us about extremes, how a world can bake and
• 54:02
  freeze on the same day, how ancient impacts can ring
• 54:05
  a planet like a bell. Venus showed us the dangers
• 54:09
  of runaway climate change, a cautionary tale written in sulfuric
• 54:14
  acid clouds and temperatures hot enough to melt lead. Earth
• 54:19
  reminded us of the miracle of life. the delicate balance
• 54:23
  of conditions that allow liquid water and breathable air, and
• 54:27
  all the complexity that emerges from those simple ingredients. Mars
• 54:33
  whispered stories of lost potential, of rivers that once flowed
• 54:37
  and atmospheres that escaped to space. Jupiter overwhelmed us with
• 54:43
  its scale, a world so massive it shapes the orbits
• 54:47
  of everything around it, a planet that's almost a star
• 54:50
  but not quite. Saturn dazzled us with its rings, those
• 54:55
  impossibly thin disks of ice and rock that encircle the
• 54:59
  planet like a cosmic halo. Uranus surprised us by lying
• 55:04
  on its side, a world knocked askew by some ancient violence.
• 55:09
  And Neptune, distant and deep blue, showed us that even
• 55:14
  in the cold outer reaches of the solar system, winds
• 55:18
  can howl faster than sound. But here's what makes this
• 55:21
  journey truly remarkable. Everything we've described, every detail about temperatures
• 55:27
  and pressures and compositions, comes from real data gathered by
• 55:31
  real spacecraft and real telescopes operated by real humans who
• 55:36
  dedicated their lives to understanding these distant worlds. The Mariner
• 55:41
  missions flew past Mercury and Venus in the 1960s and 70s,
• 55:46
  sending back the first close-up images of those scorched and
• 55:49
  shrouded worlds. The Viking landers touched down on Mars in 1976,
• 55:56
  analysing Martian soil and searching for signs of life. Voyager
• 56:01
  1 and 2 performed their grand tour of the outer
• 56:04
  planets in the late 70s and 80s, flying past Jupiter, Saturn,
• 56:10
  Uranus and Neptune. sending back images that transformed these distant
• 56:15
  lights into real places with weather and moons and mysteries.
• 56:21
  The Galileo spacecraft orbited Jupiter for eight years, diving into
• 56:27
  its atmosphere in a final suicide mission that revealed new
• 56:31
  layers of complexity. Cassini spent 13 years at Saturn, discovering
• 56:37
  geysers on Enceladus. and lakes of liquid methane on Titan
• 56:41
  before plunging into Saturn's atmosphere in 2017. These missions, these
• 56:47
  robotic explorers, have been our eyes and ears in places
• 56:51
  we cannot go. They've measured temperatures with thermometers, analysed atmospheres
• 56:58
  with spectrometers, mapped magnetic fields with magnetometers. Every fact we've
• 57:04
  shared tonight represents years of work by teams of scientists
• 57:09
  and engineers who built these spacecraft, launched them on rockets,
• 57:14
  guided them across billions of kilometres of space, and decoded
• 57:18
  the radio signals they sent back to Earth. And yet,
• 57:22
  despite all this knowledge, mysteries remain. We still don't fully
• 57:27
  understand Jupiter's core, or why Neptune is so much more
• 57:31
  active than Uranus. We don't know exactly how Saturn's hexagonal
• 57:37
  storm maintains its shape or what creates the super-rotating winds
• 57:41
  on Venus. We haven't definitively answered whether Mars ever had
• 57:45
  life or whether Europa's subsurface ocean could harbour living organisms today.
• 57:51
  The solar system keeps surprising us, revealing new puzzles even
• 57:56
  as we solve old ones. This is what makes planetary
• 58:00
  science so captivating. Every mission answers some questions, but raises
• 58:06
  new ones. Every new telescope reveals details we couldn't see before,
• 58:12
  details that don't quite fit our models, details that force
• 58:15
  us to rethink our assumptions. The solar system is a
• 58:20
  dynamic place, constantly changing on timescales, from seconds to billions
• 58:26
  of years, and we're privileged to live in an era
• 58:29
  when we can study it up close. Consider the human
• 58:32
  element of all this. When we sent Voyager past Neptune
• 58:36
  in 1989, the spacecraft was navigating by starlight, using its
• 58:41
  cameras to photograph distant stars and calculate its position. The
• 58:47
  radio signals took four hours to travel from Neptune back
• 58:51
  to Earth, so controllers couldn't steer the spacecraft in real time.
• 58:56
  They had to program everything in advance, trusting that their
• 59:00
  calculations were correct. hoping that nothing unexpected would go wrong.
• 59:05
  And it worked. Voyager 2 flew through Neptune's system exactly
• 59:10
  as planned, discovering new moons and rings and capturing images
• 59:15
  of a world no one had ever seen up close before.
• 59:18
  That mission happened over three decades ago, and Voyager is
• 59:22
  still sending data back to Earth, now exploring interstellar space
• 59:26
  beyond the influence of the sun. It carries a golden
• 59:30
  record with sounds and images from Earth, a message to
• 59:34
  any alien civilization that might someday find it drifting through
• 59:38
  the galaxy. That record includes greetings in dozens of languages,
• 59:44
  music from different cultures, photographs of people and places, and
• 59:50
  natural wonders. It's a time capsule from humanity, a reminder
• 59:56
  that we exist, that we wonder about the universe, that
• 1:00:01
  we dream of making contact with other minds among the stars.
• 1:00:06
  The Golden Record also reminds us of something important. We're
• 1:00:10
  not just passive observers of the universe. We're participants in
• 1:00:15
  a cosmic story that began with the Big Bang and
• 1:00:18
  will continue long after our sun burns out. The atoms
• 1:00:22
  in our bodies were forged in ancient stars that exploded
• 1:00:26
  billions of years ago, The iron in our blood, the
• 1:00:30
  calcium in our bones, the oxygen we breathe, all of
• 1:00:34
  it came from stellar furnaces that converted hydrogen into heavier
• 1:00:38
  elements through nuclear fusion. We are literally made of stardust,
• 1:00:44
  temporary arrangements of matter that have somehow become aware of
• 1:00:48
  their own existence. This awareness, this consciousness... allows us to
• 1:00:54
  appreciate the beauty and complexity of the solar system in
• 1:00:59
  ways that purely physical processes cannot. A storm on Jupiter
• 1:01:04
  doesn't know it's beautiful. The rings of Saturn don't marvel
• 1:01:07
  at their own delicate structure. But we do. We look
• 1:01:12
  at images from spacecraft and feel wonder. We study the
• 1:01:16
  data and piece together stories about how these worlds formed
• 1:01:19
  and evolved. We imagine what it would be like to
• 1:01:22
  float through Jupiter's clouds or stand on the surface of
• 1:01:26
  Mars watching the sun set in a butterscotch sky. And tonight,
• 1:01:31
  we've taken that imagination one step further. We've done the impossible,
• 1:01:38
  descending through every planet, experiencing conditions that would kill us instantly,
• 1:01:44
  seeing things that no camera could ever capture. This journey
• 1:01:48
  exists only in our minds. but that doesn't make it
• 1:01:52
  less valuable. Imagination is how we explore possibilities, how we
• 1:01:58
  test ideas, how we dream of futures that don't exist yet.
• 1:02:03
  Every spacecraft that's ever flown to another planet started as
• 1:02:06
  an imagination, an idea in someone's mind that gradually took
• 1:02:10
  shape as drawings and models, and finally as real hardware
• 1:02:15
  that could survive launch and navigate through space. The engineers
• 1:02:20
  who designed these missions had to imagine all the things
• 1:02:23
  that could go wrong. What if a solar panel doesn't deploy?
• 1:02:27
  What if the radio antenna gets stuck? What if the
• 1:02:31
  thrusters misfire or the computer crashes or a micrometeorite punches
• 1:02:35
  a hole in a fuel tank? They had to think
• 1:02:39
  through every possible failure mode and design backup systems and redundancies.
• 1:02:45
  They had to imagine success too. picturing the spacecraft arriving
• 1:02:50
  at its destination, executing its observations, sending data across millions
• 1:02:57
  or billions of kilometres back to Earth. This kind of
• 1:03:00
  systematic imagination, this ability to envision complex systems and predict
• 1:03:06
  how they'll behave, is what allows us to explore the
• 1:03:09
  solar system without leaving Earth. We send robots to do
• 1:03:14
  the exploring for us, Machines that can withstand radiation and
• 1:03:19
  extreme temperatures and crushing pressures that would destroy biological organisms.
• 1:03:26
  These robots are our proxies, our representatives in hostile environments,
• 1:03:32
  gathering data that we analyse to build understanding. But robots
• 1:03:37
  have limitations. They can only measure what they're designed to measure.
• 1:03:41
  They can only go where we send them. they can't
• 1:03:44
  improvise or adapt the way a human explorer could. That's
• 1:03:48
  why some people dream of sending humans to Mars, of
• 1:03:51
  establishing permanent bases on the moon, of someday building spacecraft
• 1:03:56
  that could take people to the outer planets. These dreams
• 1:04:00
  face enormous challenges, technical and financial and biological. The radiation
• 1:04:06
  exposure alone would be life-threatening. The psychological effects of spending
• 1:04:11
  years in a cramped spacecraft millions of kilometres from home
• 1:04:14
  would test anyone's sanity. And yet, the dream persists. There's
• 1:04:20
  something deeply human about wanting to go places ourselves. To
• 1:04:25
  see things with our own eyes, rather than through cameras.
• 1:04:29
  To touch alien soil with our own hands, rather than
• 1:04:32
  through robotic manipulators. Maybe future generations will develop technologies that
• 1:04:38
  make such journeys possible. Maybe they'll find ways to protect
• 1:04:42
  astronauts from radiation, to generate artificial gravity, to recycle air
• 1:04:47
  and water and grow food in space. Maybe they'll build
• 1:04:51
  fusion rockets or antimatter drives or some propulsion system we
• 1:04:54
  haven't imagined yet that could cut travel times from years
• 1:04:58
  to months or weeks. Or maybe humans will never physically
• 1:05:02
  visit the outer planets. Maybe we'll always explore through proxies,
• 1:05:06
  through increasingly sophisticated robots and artificial intelligence systems that can
• 1:05:12
  make decisions autonomously. Maybe virtual reality will become so convincing
• 1:05:18
  that experiencing another planet through a robot's sensors will feel
• 1:05:23
  as real as being there in person. The technology is
• 1:05:27
  already moving in that direction. Scientists can put on VR
• 1:05:31
  headsets and walk across the surface of Mars using data
• 1:05:35
  from rovers, experiencing the landscape in three dimensions, feeling almost
• 1:05:41
  as if they're really there. These technologies blur the line
• 1:05:45
  between physical and virtual exploration. When you're immersed in a
• 1:05:50
  high-fidelity simulation of Jupiter's atmosphere, watching lightning flash in the
• 1:05:56
  clouds around you, feeling the turbulence of updrafts and downdrafts,
• 1:06:01
  hearing the roar of winds, is that experience fundamentally different
• 1:06:06
  from being there physically. Your body is safe on Earth,
• 1:06:11
  but your consciousness is engaged with another world, processing information,
• 1:06:16
  forming memories, experiencing wonder. In some sense, you are exploring Jupiter,
• 1:06:24
  even if your physical body never leaves the ground. This
• 1:06:27
  raises philosophical questions about the nature of experience and presence,
• 1:06:32
  What does it mean to visit a place? Does it
• 1:06:34
  require physical proximity? Or is it enough to gather information
• 1:06:38
  about that place through sensors and reconstruct it in your mind?
• 1:06:43
  When you look at a photograph of Saturn's rings, you're
• 1:06:46
  seeing light that reflected off those rings, travelled across the
• 1:06:51
  solar system, was captured by a spacecraft's camera, converted to
• 1:06:57
  digital data, transmitted to Earth, processed by computers and displayed
• 1:07:03
  on a screen. The light that enters your eyes is
• 1:07:07
  not the same light that bounced off Saturn's rings, yet
• 1:07:10
  somehow you feel connected to that distant place. This chain
• 1:07:15
  of information transfer is what allows us to know anything
• 1:07:18
  about the universe beyond our immediate surroundings. We're always interpreting signals,
• 1:07:24
  whether it's light from distant galaxies or radio waves from spacecraft,
• 1:07:29
  or seismic waves travelling through Earth's interior. We never experience
• 1:07:35
  reality directly. We experience our brain's interpretation of signals received
• 1:07:41
  through our senses. In that sense, all experience is virtual,
• 1:07:46
  a mental model constructed from incomplete information. But some models
• 1:07:51
  are more accurate than others. The scientific method gives us
• 1:07:56
  tools for testing our models against reality, for distinguishing between
• 1:08:01
  accurate representations and wishful thinking. When multiple independent lines of
• 1:08:07
  evidence all point to the same conclusion, we can be
• 1:08:10
  confident that our model reflects something real about the universe.
• 1:08:15
  The composition of Jupiter's atmosphere isn't just speculation. It's based
• 1:08:20
  on spectroscopy, on measurements from the Galileo probe, on theoretical
• 1:08:26
  calculations that match observations. The model might not be perfect,
• 1:08:30
  but it's grounded in data, refined through decades of study.
• 1:08:35
  This accumulation of knowledge is one of humanity's greatest achievements.
• 1:08:40
  Each generation builds on the work of previous generations, adding
• 1:08:44
  new observations, refining theories, correcting errors. The process is gradual,
• 1:08:52
  sometimes frustratingly slow, but it's reliable. The knowledge we have
• 1:08:57
  about the solar system today is vastly more detailed and
• 1:09:01
  accurate than what we knew 50 years ago. And 50
• 1:09:05
  years from now, our descendants will know even more. They'll
• 1:09:09
  have visited places we can only imagine, answered questions we
• 1:09:14
  haven't thought to ask, discovered phenomena that will surprise and
• 1:09:18
  delight them. and they'll still have mysteries to solve. The
• 1:09:22
  universe is vast and complex, and there's no reason to
• 1:09:25
  think we'll ever reach a point where we understand everything.
• 1:09:29
  There will always be new frontiers, new questions, new challenges
• 1:09:34
  that push the limits of our knowledge and technology. That's
• 1:09:38
  not a failure. It's a feature. The universe is interesting
• 1:09:43
  precisely because it's not simple, because it rewards curiosity with
• 1:09:47
  endless discoveries, As we conclude our journey through the solar system,
• 1:09:52
  it's worth reflecting on what we've learned. Not just facts
• 1:09:56
  about planetary atmospheres and core compositions, but something deeper about
• 1:10:01
  the nature of exploration itself. We've seen that the solar
• 1:10:05
  system is diverse beyond imagination, that each planet has its
• 1:10:10
  own personality, its own story to tell. We've recognized that
• 1:10:15
  human curiosity drives us to explore even when there's no
• 1:10:20
  immediate practical benefit. That we build spacecraft and telescopes because
• 1:10:25
  we want to know what's out there, because we can't
• 1:10:27
  help but wonder. We've acknowledged the limitations of our current
• 1:10:31
  technology while dreaming of future advances that might overcome those limitations.
• 1:10:38
  We've appreciated the work of thousands of scientists and engineers
• 1:10:42
  who've dedicated their careers to expanding human knowledge. And we've experienced,
• 1:10:47
  if only in imagination, the humbling realization that Earth is special,
• 1:10:54
  that our planet's combination of conditions suitable for life is
• 1:10:58
  rare and precious, that we should protect and cherish this
• 1:11:02
  world that gave rise to us. The journey through every
• 1:11:05
  planet has taken us from the scorching surface of Mercury
• 1:11:09
  to the frozen depths of Neptune, through atmospheres thick and thin,
• 1:11:14
  through oceans of liquid hydrogen and superionic ice, through cores
• 1:11:19
  of metal compressed to impossible densities. We've experienced conditions that
• 1:11:24
  span thousands of degrees in temperature and millions of atmospheres
• 1:11:29
  in pressure. We've seen weather systems that dwarf anything on
• 1:11:32
  Earth and magnetic fields that stretch millions of kilometers into space.
• 1:11:37
  And through it all, we've carried with us the knowledge
• 1:11:39
  that this journey, while impossible in reality, represents real places
• 1:11:44
  that exist right now, orbiting the same sun that warms
• 1:11:49
  our faces on Earth. Those planets are out there, spinning
• 1:11:53
  through space, their atmospheres churning, their cores cooling, their surfaces
• 1:11:59
  being slowly reshaped by impacts and volcanism and the patient
• 1:12:04
  work of geological time. They don't care that we exist.
• 1:12:09
  They don't notice our spacecraft or our telescopes or our curiosity.
• 1:12:14
  They simply are, following the laws of physics, moving through
• 1:12:18
  their orbits, existing as they have for billions of years
• 1:12:22
  and will continue to exist for billions more. But we care,
• 1:12:28
  we notice, we wonder, and that makes all the difference.
• 1:12:32
  The universe doesn't need us to observe it. but observation
• 1:12:36
  gives meaning to existence in a way that pure physical
• 1:12:39
  processes cannot. When we look at Saturn's rings and feel awe,
• 1:12:44
  we're adding something to the universe that wasn't there before,
• 1:12:47
  a subjective experience, a moment of consciousness appreciating beauty. These
• 1:12:53
  moments are fleeting, lasting only as long as we do,
• 1:12:57
  but they're real, and they matter, at least to us.
• 1:13:01
  So as you prepare to drift off to sleep tonight,
• 1:13:04
  Carried gently by the rhythm of your breathing, remember that
• 1:13:07
  you've travelled farther than any human has ever gone. You've
• 1:13:12
  descended through worlds that would destroy spacecraft in seconds. You've
• 1:13:16
  witnessed phenomena that challenge our understanding of physics. You've imagined
• 1:13:21
  the unimaginable and made it feel real, if only for
• 1:13:25
  a moment. The solar system is vast and strange and beautiful,
• 1:13:30
  and you wonders tonight. Jupiter's great red spot will keep swirling.
• 1:13:36
  Saturn's rings will keep orbiting. Neptune's winds will keep howling
• 1:13:41
  through that deep blue atmosphere. And somewhere, a spacecraft will
• 1:13:46
  keep transmitting data across the vast emptiness of space, adding
• 1:13:50
  new details to our understanding, answering old questions and raising
• 1:13:55
  new ones. The journey continues, not just for spacecraft and scientists,
• 1:14:02
  but for anyone who looks up at the night sky
• 1:14:05
  and wonders what's out there. Every time you see a
• 1:14:09
  bright point of light moving against the stars, you might
• 1:14:12
  be seeing Jupiter, or Saturn, or Mars. Those aren't just lights.
• 1:14:19
  They're worlds, places with landscapes and weather, and histories that
• 1:14:23
  stretch back billions of years. And now you know a
• 1:14:27
  little more about what they're really like, about what makes
• 1:14:31
  each one unique, about the incredible diversity that exists in
• 1:14:35
  our cosmic neighbourhood, fly through every planet in our solar system.
• 1:14:40
  Sleep finds us in different ways, sometimes gradually like the
• 1:14:44
  fading of daylight, other times suddenly like a switch being flipped.
• 1:14:49
  But wherever you are right now, whatever time it is
• 1:14:51
  in your corner of the world, you've journeyed through impossible
• 1:14:55
  distances tonight. You've touched the face of worlds that exist
• 1:15:00
  only as points of light in our telescopes, transform them
• 1:15:04
  from distant abstractions into places with texture and depth and character.
• 1:15:12
  There's something profound about understanding scale. When we say Jupiter
• 1:15:16
  is 300 times more massive than Earth, the number doesn't
• 1:15:19
  capture the reality. But when you imagine descending through layer
• 1:15:23
  after layer of atmosphere, sinking through thousands of kilometres of
• 1:15:28
  liquid hydrogen, falling through metallic hydrogen oceans that conduct electricity
• 1:15:33
  like copper wire, suddenly that mass becomes tangible. You feel
• 1:15:38
  it pressing down from every direction, that enormous weight of
• 1:15:42
  a world so large it almost became a star. The
• 1:15:47
  same applies to temperature. Saying Venus is 470 degrees Celsius
• 1:15:53
  tells you it's hot, but imagining the surface glowing dull
• 1:15:57
  red Hot enough that certain metals would puddle on the
• 1:16:00
  ground like water. Hot enough that lead would boil away
• 1:16:05
  into vapour. That makes it real. These aren't just numbers
• 1:16:10
  in a textbook. They're conditions that exist right now on
• 1:16:14
  an actual world you could point to in the sky,
• 1:16:16
  and pressure. The crushing weight of 92 Earth atmospheres at
• 1:16:22
  Venus' surface seems abstract, until you picture yourself a kilometer
• 1:16:27
  underwater on Earth, feeling that same pressure, knowing that going
• 1:16:32
  deeper would only make it worse. Then, multiply that by
• 1:16:36
  the descent through Jupiter, where pressures reach millions of atmospheres,
• 1:16:42
  where the very nature of matter changes, where hydrogen stops
• 1:16:46
  being a gas and becomes liquid, then stops being an
• 1:16:51
  insulator and becomes a conductor of electricity. These extreme conditions
• 1:16:57
  teach us something important about Earth. Our planet sits in
• 1:17:01
  what scientists call the habitable zone, that narrow range of
• 1:17:07
  distances from the sun where temperatures allow liquid water to
• 1:17:11
  exist on the surface. Too close, like Venus, and water
• 1:17:16
  boils away. Too far, like Mars, and water freezes solid.
• 1:17:20
  But it's not just about distance. Venus is roughly the
• 1:17:24
  same size as Earth, made of similar materials, yet its
• 1:17:28
  climate spiralled into a runaway greenhouse effect that created the
• 1:17:32
  hellscape we see today. What made Earth different? Partly luck,
• 1:17:38
  partly the right combination of factors that kept our climate
• 1:17:42
  stable for billions of years. We have plate tectonics that
• 1:17:46
  recycles carbon dioxide, preventing too much from building up in
• 1:17:51
  the atmosphere. We have a large moon, that stabilizes our
• 1:17:55
  axial tilt, preventing wild climate swings. We have Jupiter acting
• 1:18:02
  as a cosmic vacuum cleaner, its powerful gravity deflecting or
• 1:18:07
  capturing asteroids and comets that might otherwise bombard the inner
• 1:18:12
  solar system. All these factors working together created conditions where
• 1:18:18
  life could emerge and persist. Simple single-celled organisms appeared on
• 1:18:24
  Earth within a few hundred million years of the planet's formation,
• 1:18:28
  remarkably quickly in geological terms. Those simple cells eventually evolved
• 1:18:34
  into the incredible diversity of life we see today, from
• 1:18:38
  bacteria to blue whales, from microscopic plankton to towering redwood trees.
• 1:18:45
  And somewhere along that evolutionary path, consciousness emerged, the ability
• 1:18:50
  to observe and question and wonder about the universe. That
• 1:18:55
  consciousness allows you to do what you've done tonight, to
• 1:18:58
  imagine yourself flying through planets, experiencing conditions no living thing
• 1:19:04
  could survive, gathering knowledge about worlds you'll never physically visit,
• 1:19:10
  This ability to learn about distant places through observation and reasoning,
• 1:19:15
  to build mental models of reality that extend far beyond
• 1:19:19
  direct experience, is perhaps the most remarkable feature of human cognition.
• 1:19:25
  Consider what it takes to understand Jupiter's interior structure. Nobody
• 1:19:29
  has drilled into Jupiter's core. We can't sample the metallic
• 1:19:33
  hydrogen directly or measure its properties in a laboratory. Yet
• 1:19:38
  we can deduce what must be there based on Jupiter's mass,
• 1:19:42
  its gravitational field, its rotation rate, its magnetic field. We
• 1:19:47
  can run computer simulations that model how matter behaves under
• 1:19:51
  extreme pressure and temperature. We can compare our predictions to
• 1:19:56
  observations and refine our models until they match what we see.
• 1:20:02
  This process of scientific inference has revealed truths about the
• 1:20:06
  universe that would have seemed like magic to our ancestors.
• 1:20:11
  They looked at Jupiter and saw a bright wandering star,
• 1:20:15
  important for astrology perhaps, but fundamentally mysterious. We look at
• 1:20:20
  Jupiter and see a world with specific composition, structure and history.
• 1:20:26
  We understand how it formed from the same cloud of
• 1:20:28
  gas and dust that created the sun. We know why
• 1:20:32
  it has moons and rings. We can predict its future
• 1:20:35
  evolution over billions of years. Yet even with all this knowledge,
• 1:20:40
  Jupiter retains its mystery. The Great Red Spot has persisted
• 1:20:45
  for centuries, but we still don't fully understand what sustains it,
• 1:20:50
  why it hasn't dissipated like storms on Earth do. The
• 1:20:54
  precise structure of Jupiter's core remains uncertain. with recent data
• 1:21:00
  suggesting it might be fuzzy or diluted rather than a
• 1:21:04
  distinct solid ball. The planet generates more heat than it
• 1:21:08
  receives from the Sun, but the exact mechanisms driving this
• 1:21:13
  internal heat engine are still being researched. These remaining mysteries
• 1:21:17
  aren't failures of science. They're invitations to deeper understanding, puzzles
• 1:21:23
  that motivate the next generation of missions and observations. The
• 1:21:28
  Juno spacecraft currently orbiting Jupiter is designed specifically to answer
• 1:21:33
  some of these questions, mapping the planet's gravitational and magnetic
• 1:21:37
  fields with unprecedented precision, peering beneath the cloud tops with
• 1:21:42
  instruments that can see through the thick atmosphere. Each planet
• 1:21:47
  we visited tonight has similar mysteries waiting to be solved.
• 1:21:52
  Mercury's enormous iron core suggests something dramatic happened during its formation.
• 1:21:59
  But we don't know exactly what. Venus lost its water
• 1:22:02
  billions of years ago, but we don't know if it
• 1:22:05
  ever had oceans like Earth, or if the water was
• 1:22:08
  delivered later and then lost. Mars clearly had liquid water
• 1:22:13
  flowing on its surface in the past, carving massive channels
• 1:22:16
  and possibly filling ancient ocean basins. but we don't know
• 1:22:20
  how long that water persisted or where it all went.
• 1:22:24
  The ice giants Uranus and Neptune present their own puzzles.
• 1:22:29
  Why is Uranus so much less active than Neptune despite
• 1:22:32
  receiving more sunlight? What knocked Uranus onto its side? Why
• 1:22:38
  do both planets have such strangely tilted and offset magnetic fields?
• 1:22:43
  The Voyager flybys gave us our only close-up look at
• 1:22:47
  these worlds. brief snapshots taken during quick passes that lasted
• 1:22:52
  just days. We need new missions to return to the
• 1:22:55
  ice giants, to orbit them, and study them over complete
• 1:22:59
  seasonal cycles. These future missions will build on the legacy
• 1:23:04
  of exploration that began in the early space age. The
• 1:23:08
  first spacecraft to visit another planet was Mariner 2, which
• 1:23:12
  flew past Venus in 1962. That mission lasted only 42
• 1:23:16
  minutes at closest approach. but it revolutionized our understanding of Venus,
• 1:23:21
  revealing the planet's extreme surface temperature and confirming that the
• 1:23:25
  thick atmosphere was mostly carbon dioxide. Every mission since then
• 1:23:30
  has added layers of detail, transforming Venus from a mysterious,
• 1:23:35
  shrouded world into a place we can describe with scientific precision.
• 1:23:40
  The same pattern holds for every planet. Our first glimpses
• 1:23:44
  were blurry and incomplete, raising more questions than they answered
• 1:23:49
  But each subsequent mission brought clearer images, better data, deeper understanding.
• 1:23:55
  The Mariner missions gave way to Viking and Voyager. Those
• 1:23:59
  gave way to Galileo and Cassini and Juno and New Horizons.
• 1:24:04
  Each generation of spacecraft carried more sophisticated instruments, capable of
• 1:24:09
  measuring things their predecessors couldn't detect. And the pace of
• 1:24:13
  discovery continues accelerating. In the past decade, We've orbited Mercury
• 1:24:20
  with the Messenger spacecraft, studied Saturn's moons in detail with Cassini,
• 1:24:25
  flown past Pluto with New Horizons, and begun long-term observation
• 1:24:31
  of Jupiter with Juno. Future missions, planned or under development,
• 1:24:37
  will return samples from Mars, explore Europa's subsurface ocean, visit
• 1:24:43
  Neptune and Uranus, and continue pushing the boundaries of what
• 1:24:47
  we know about our solar system. But space exploration isn't
• 1:24:52
  just about accumulating facts. It's about changing perspective, about seeing
• 1:24:57
  ourselves and our place in the universe differently. The famous
• 1:25:02
  Earthrise photograph, taken by Apollo 8 astronauts orbiting the moon,
• 1:25:07
  showed our planet as a fragile blue marble floating in
• 1:25:11
  the darkness of space. That image helped spark the environmental movement,
• 1:25:18
  making people realize that Earth's resources are finite, that we
• 1:25:24
  need to take care of our planet because it's the
• 1:25:27
  only one we have. Carl Sagan articulated this perspective beautifully
• 1:25:32
  when describing the pale blue dot photograph taken by Voyager
• 1:25:35
  1 from beyond Neptune's orbit. In that image, Earth appears
• 1:25:40
  as a tiny speck, less than a pixel, suspended in
• 1:25:44
  a beam of scattered sunlight. Sagan wrote about how that
• 1:25:48
  dot contains everyone you love, everyone you know, every human
• 1:25:52
  who ever lived, all playing out their dramas on that
• 1:25:56
  mote of dust suspended in a sunbeam. He urged us
• 1:26:00
  to cherish and preserve that pale blue dot, the only
• 1:26:04
  home we've ever known. This cosmic perspective doesn't diminish human experience,
• 1:26:10
  it enriches it. Knowing that we're inhabitants of one planet
• 1:26:14
  among many, one solar system among billions, one galaxy among trillions,
• 1:26:21
  doesn't make our lives less meaningful. It makes them more precious.
• 1:26:26
  We're conscious beings capable of understanding our place in this
• 1:26:30
  vast cosmos, of appreciating beauty and creating meaning in a
• 1:26:35
  universe that's otherwise indifferent to our existence. The journey through
• 1:26:41
  every planet reminds us of both our smallness and our significance.
• 1:26:46
  We're tiny compared to Jupiter, fragile compared to Venus' crushing atmosphere,
• 1:26:53
  brief compared to the billions of years these worlds have existed.
• 1:26:57
  Yet we're the ones asking questions, building spacecraft, analysing data,
• 1:27:03
  piecing together the story of how the solar system formed
• 1:27:07
  and evolved. We're the universe becoming aware of itself, matter
• 1:27:13
  organized in such a way that it can contemplate its
• 1:27:16
  own existence. This self-awareness comes with responsibility. We're the only
• 1:27:23
  species on Earth capable of understanding the threats facing our planet,
• 1:27:28
  from climate change to asteroid impacts to the eventual death
• 1:27:33
  of our sun billions of years in the future. We're
• 1:27:37
  also the only species capable of doing anything about those threats.
• 1:27:41
  The knowledge we gain from studying other planets isn't just
• 1:27:44
  academically interesting. It's practically important for understanding how planetary climates work,
• 1:27:51
  how magnetic fields protect atmospheres, how impacts shape surfaces. Venus
• 1:27:57
  teaches us about runaway greenhouse effects. Mars shows us what
• 1:28:01
  happens when a planet loses its magnetic field and atmosphere.
• 1:28:06
  Jupiter demonstrates how gravitational interactions can stabilize or destabilize entire
• 1:28:13
  planetary systems. Every world we study adds to our understanding
• 1:28:18
  of how planets work in general, including our own. This
• 1:28:22
  knowledge might prove crucial for humanity's long-term survival. Some people
• 1:28:27
  argue that we should focus on solving Earth's problems before
• 1:28:31
  spending resources on space exploration. but this represents a false choice.
• 1:28:37
  The same technologies that enable space exploration often have terrestrial applications.
• 1:28:45
  Satellites monitor Earth's climate, track storms, enable global communications. Planetary
• 1:28:53
  science helps us understand climate change. Materials developed for spacecraft
• 1:28:59
  find uses in everyday products. The challenge of keeping astronauts
• 1:29:03
  alive in hostile environments drives innovations in recycling, life support
• 1:29:09
  and sustainable living. More fundamentally, exploration is part of what
• 1:29:14
  makes us human. Our ancestors didn't need to cross oceans
• 1:29:18
  or climb mountains or explore polar regions, but they did anyway,
• 1:29:22
  driven by curiosity and the desire to see what was
• 1:29:25
  beyond the horizon. That same impulse drives space exploration today.
• 1:29:32
  We explore because we can, because we're curious, because the
• 1:29:36
  universe is fascinating and we want to understand it better.
• 1:29:40
  And there's a practical argument too. Eventually, Earth will become uninhabitable.
• 1:29:46
  The sun grows brighter over time as it ages, and
• 1:29:49
  in about a billion years, Earth's oceans will boil away.
• 1:29:53
  Long before that, we might face catastrophic asteroid impacts or
• 1:29:57
  supervolcano eruptions or other existential threats. Having the capability to
• 1:30:03
  live elsewhere, whether on other planets or in space habitats,
• 1:30:08
  provides insurance against extinction. It's the ultimate backup plan for humanity.
• 1:30:14
  This long-term thinking requires patience. We won't colonise Mars in
• 1:30:19
  the next decade or build cities on Europa in this century.
• 1:30:23
  But we can take steps in that direction, learning how
• 1:30:26
  to live off Earth, developing technologies that will be needed
• 1:30:30
  for permanent settlement, inspiring young people to pursue careers in
• 1:30:34
  science and engineering. Every mission to another planet, every robot
• 1:30:39
  we send to explore distant worlds, moves us closer to
• 1:30:43
  a future where humanity is no longer confined to a
• 1:30:46
  single planet. That future might seem like science fiction. But
• 1:30:50
  so did the idea of walking on the moon until
• 1:30:53
  we actually did it. So did the concept of sending
• 1:30:57
  spacecraft to every planet in the solar system until Voyager
• 1:31:01
  made it reality. So did the notion of landing rovers
• 1:31:04
  on Mars and driving them around for years until spirit
• 1:31:08
  and opportunity and curiosity and perseverance proved it was possible.
• 1:31:15
  What seems impossible today might become routine tomorrow. given enough
• 1:31:20
  time and effort and ingenuity. As you settle deeper into rest,
• 1:31:25
  your breathing slowing, your thoughts drifting, remember that you've touched
• 1:31:29
  infinity tonight. You've experienced worlds beyond imagining, descended through atmospheres
• 1:31:35
  that would tear apart any machine we could build, witnessed
• 1:31:39
  beauty and violence on scales that dwarf anything on earth.
• 1:31:44
  These worlds exist independent of our observations, spinning through space
• 1:31:49
  according to physical laws. But your awareness of them adds
• 1:31:53
  something new to the universe. A moment of consciousness appreciating
• 1:31:58
  the vast diversity of creation. The solar system will continue
• 1:32:02
  its ancient dance long after you and everyone you know
• 1:32:05
  has returned to dust. Jupiter will keep rotating every 10 hours.
• 1:32:11
  Saturn's rings will keep orbiting, though they're gradually falling into
• 1:32:15
  the planet. and might disappear in a few hundred million years.
• 1:32:20
  Uranus will keep rolling along its tilted axis. Neptune's winds
• 1:32:25
  will keep howling. Mercury will keep baking and freezing. Venus
• 1:32:30
  will keep crushing and burning. Mars will keep dreaming of
• 1:32:34
  the water it lost. Earth will keep spinning, its inhabitants
• 1:32:38
  hopefully learning to take better care of their precious home.
• 1:32:42
  And somewhere out there, beyond the planets, Beyond the Kuiper
• 1:32:46
  belt where Pluto orbits, beyond the scattered disk of icy bodies,
• 1:32:51
  beyond the Oort cloud that marks the true edge of
• 1:32:54
  the Sun's gravitational influence, the Voyager spacecraft continue their journey
• 1:32:59
  into interstellar space. They're still transmitting data, still functioning after
• 1:33:05
  more than four decades in space, still carrying those golden
• 1:33:09
  records with messages from Earth. Someday, billions of years from now,
• 1:33:15
  Long after the sun has swelled into a red giant
• 1:33:18
  and consumed the inner planets. Long after it's shed its
• 1:33:22
  outer layers and faded to a white dwarf. Long after
• 1:33:26
  the solar system as we know it has ceased to exist.
• 1:33:29
  Those golden records might still be out there, drifting through
• 1:33:34
  the galaxy. They'll be the last remnants of our civilization,
• 1:33:40
  archaeological artifacts from a species that looked up at the
• 1:33:44
  stars and wondered what was out there, that built machines
• 1:33:49
  to explore places they couldn't go themselves, that imagined flying
• 1:33:53
  through every planet and then actually sent robots to see
• 1:33:57
  if they were right. That's the legacy of the journey
• 1:34:00
  we've taken tonight. Not just knowledge about planetary atmospheres and
• 1:34:04
  core compositions, but something deeper about who we are as
• 1:34:08
  a species, about our curiosity and creativity and determination to
• 1:34:14
  understand the universe we inhabit. We're explorers by nature, driven
• 1:34:20
  to see what's beyond the next hill, the next ocean,
• 1:34:23
  the next planet. That drive has taken us from caves
• 1:34:27
  to cities to the moon, and someday it might take
• 1:34:30
  us to the stars. But for now, for tonight, it's
• 1:34:35
  enough to have travelled in imagination through every planet in
• 1:34:38
  our solar system. You've experienced more than most people ever will.
• 1:34:43
  journeying to places that exist only as data and images
• 1:34:46
  and scientific models. You've made those distant worlds feel real,
• 1:34:51
  if only for a moment, transforming numbers and facts into
• 1:34:55
  visceral experience. That's the power of imagination combined with knowledge,
• 1:35:01
  the ability to construct mental realities that feel as vivid
• 1:35:05
  as anything you could touch. So rest now, knowing you've
• 1:35:10
  accomplished something remarkable. You've flown through Mercury's scorched landscape and
• 1:35:16
  Venus' toxic clouds. You've breathed Earth's gentle atmosphere and walked
• 1:35:22
  Mars' rusty deserts. You've descended through Jupiter's endless storms and
• 1:35:28
  Saturn's elegant haze. You've experienced Uranus' strange sideways rotation and
• 1:35:34
  Neptune's fierce winds. You've touched every world in our cosmic neighbourhood,
• 1:35:40
  gathering them into your consciousness like precious stones, each one unique,
• 1:35:45
  each one beautiful in its own way. The journey ends
• 1:35:49
  where it began, here in this quiet moment, wherever you are,
• 1:35:54
  whatever time it is. The planets will still be there tomorrow,
• 1:35:59
  waiting for the next generation of explorers, the next wave
• 1:36:03
  of missions. the next person who looks up at the
• 1:36:07
  night sky and wonders what it would be like to
• 1:36:10
  visit those distant lights. And maybe someday, centuries or millennia
• 1:36:15
  from now, humans will actually fly through those planets, not
• 1:36:20
  in imagination, but in reality, using technologies we haven't invented yet,
• 1:36:26
  driven by the same curiosity that motivated tonight's journey. Until then,
• 1:36:32
  we explore through our minds and our machines, Gathering knowledge
• 1:36:36
  piece by piece, building understanding gradually, always reaching toward mysteries
• 1:36:42
  just beyond our grasp. That reaching defines us as much
• 1:36:46
  as anything. That refusal to accept ignorance when knowledge is possible.
• 1:36:52
  That determination to understand even when understanding is difficult. We're
• 1:36:58
  the species that figured out how to split atoms and
• 1:37:01
  sequence genomes and send messages across the solar system at
• 1:37:05
  the speed of light. We're the ones who imagined flying
• 1:37:08
  through planets and then did the math to figure out
• 1:37:11
  what we'd actually experience if we could. Sweet dreams, cosmic traveler.
• 1:37:17
  May your rest be as peaceful as the silence between
• 1:37:20
  the stars, as gentle as the solar wind pushing outward
• 1:37:24
  from the sun, as deep as the cores of the
• 1:37:27
  planets you've visited tonight. The universe continues its eternal motion
• 1:37:32
  around you, indifferent to your presence, yet somehow made more
• 1:37:37
  complete by your awareness of it. You are stardust that
• 1:37:42
  learned to wonder, atoms that somehow became conscious, a temporary
• 1:37:47
  pattern in the cosmic dance that will someday dissolve back
• 1:37:51
  into the elements from which it came. But while you exist,
• 1:37:55
  while consciousness flickers in your neurons and thoughts flow through
• 1:37:58
  your mind, you carry with you the knowledge of worlds
• 1:38:01
  beyond your own. You've touched the solar system tonight in
• 1:38:06
  ways that matter, ways that connect you to the grand
• 1:38:10
  story of exploration and discovery that defines our species. Rest
• 1:38:15
  now in that knowledge, secure in the understanding that you're
• 1:38:18
  part of something larger than yourself, a civilization that looks
• 1:38:22
  outward and asks questions and seeks answers among the planets
• 1:38:25
  and stars. The journey through every planet is complete. The
• 1:38:30
  solar system has revealed its secrets, at least the ones
• 1:38:33
  we currently understand, but the universe holds infinitely more mysteries,
• 1:38:39
  more worlds orbiting other stars, more galaxies beyond our own,
• 1:38:44
  more questions waiting for curious minds to ask them. Tonight,
• 1:38:50
  you've explored eight planets. Tomorrow, who knows what discoveries await?
• 1:38:56
  What new missions will launch? What new data will arrive
• 1:39:00
  from distant spacecraft? What new understanding will emerge from scientists
• 1:39:05
  analysing observations and running simulations? The adventure continues, not just
• 1:39:12
  in space, but here on Earth, in laboratories and universities
• 1:39:16
  and observatories, in the minds of people who dedicate their
• 1:39:20
  lives to understanding the cosmos. And it continues in moments
• 1:39:24
  like this, when someone takes the time to imagine what
• 1:39:27
  it would be like to fly through every planet, to
• 1:39:31
  experience the impossible, to transform scientific knowledge into vivid mental
• 1:39:36
  imagery that makes distant worlds feel close and real and meaningful.
• 1:39:43
  Thank you for taking this journey. Thank you for letting
• 1:39:47
  your imagination soar through the solar system, for caring enough
• 1:39:51
  about these distant worlds to spend time learning about them.
• 1:39:56
  The universe is vast and ancient and mostly empty, but
• 1:40:01
  it's also filled with wonders beyond counting, and you've experienced
• 1:40:05
  a few of them tonight. May that experience stay with you,
• 1:40:09
  enriching your understanding of our place in the cosmos, reminding
• 1:40:13
  you that we inhabit one small world among many, precious
• 1:40:18
  and fragile and worth protecting. Good night, explorer. May your
• 1:40:24
  dreams take you to places even more distant and strange
• 1:40:28
  than the planets we visited, and when you wake, may
• 1:40:32
  you carry with you a sense of wonder about the
• 1:40:34
  universe and our place in it, a reminder that we're
• 1:40:39
  surrounded by mysteries and beauty. on scales, both cosmic and intimate.
• 1:40:46
  The solar system is your backyard, the stars your distant neighbours,
• 1:40:52
  the universe your home. Never stop wondering, never stop exploring,
• 1:40:58
  never stop looking up at the night sky and asking
• 1:41:01
  what's out there. The planets are waiting. The solar system
• 1:41:05
  stretches out in the darkness, each world spinning in its
• 1:41:08
  appointed path following the same choreography it's performed for billions
• 1:41:12
  of years. But our journey isn't quite finished. There's one
• 1:41:17
  more perspective we need to consider, one final way to
• 1:41:21
  understand what we've experienced tonight. Because flying through these planets,
• 1:41:26
  descending through their atmospheres and cores, teaches us something that
• 1:41:31
  goes beyond planetary science. It reveals patterns, connections, Threads that
• 1:41:38
  tie these worlds together into a single coherent story. Think
• 1:41:42
  about the journey from inner to outer solar system. We
• 1:41:46
  started with Mercury, small and dense, mostly metal, baked by
• 1:41:51
  the nearby sun. Then Venus, similar in size to Earth
• 1:41:55
  but wrapped in a runaway greenhouse nightmare. Earth itself, the
• 1:42:00
  blue jewel, the only world we know that harbours life. Mars,
• 1:42:06
  cold and dry. holding onto memories of when it was
• 1:42:09
  warm and wet. These four worlds share something fundamental. They're rocky,
• 1:42:16
  they have solid surfaces you could theoretically stand on. They
• 1:42:21
  formed in the hot inner regions of the solar nebula,
• 1:42:24
  where metals and silicates could condense, while lighter elements were
• 1:42:28
  blown away by the young sun's radiation. But then we
• 1:42:32
  crossed an invisible boundary in space, moving beyond the frost line,
• 1:42:36
  that distance from the Sun where temperatures dropped low enough
• 1:42:39
  for water ice and other volatile compounds to freeze solid
• 1:42:43
  during the solar system's formation. Beyond that line, planets could
• 1:42:48
  grow much larger because there was simply more material available.
• 1:42:53
  Ice and gas were far more abundant than rock and metal,
• 1:42:58
  and gravity could gather enormous quantities of these lighter materials
• 1:43:02
  into massive worlds. Jupiter and Saturn. The gas giants are
• 1:43:07
  fundamentally different from the inner planets. They're mostly hydrogen and helium,
• 1:43:12
  the same elements that make up the sun itself. They're
• 1:43:16
  failed stars in a sense, worlds that gathered enough material
• 1:43:20
  to become enormous but not quite enough to ignite nuclear
• 1:43:23
  fusion in their cores. If Jupiter had been about 80
• 1:43:27
  times more massive, it would have become a brown dwarf,
• 1:43:30
  capable of fusing deuterium. If it had been about 1300
• 1:43:35
  times more massive, it would have become a true star,
• 1:43:39
  fusing hydrogen and bathing the solar system in light from
• 1:43:43
  two suns instead of one. The ice giants Uranus and
• 1:43:48
  Neptune represent yet another category. They're smaller than the gas giants,
• 1:43:54
  but still enormous compared to Earth. Their composition is different too,
• 1:43:59
  with much higher proportions of water, methane, and ammonia mixed
• 1:44:04
  with their hydrogen and helium. These compounds were abundant in
• 1:44:09
  the cold outer regions where these planets formed, and they
• 1:44:13
  give Uranus and Neptune their distinctive blue-green colours and their
• 1:44:17
  exotic internal structures with those superionic ice layers. This progression
• 1:44:23
  from rocky worlds to gas giants to ice giants isn't random.
• 1:44:28
  It's a direct consequence of how planetary systems form from
• 1:44:31
  disks of gas and dust orbiting young stars. The temperature
• 1:44:36
  gradient in the disk determines what materials can condense at
• 1:44:39
  different distances. The density of material determines how quickly planets
• 1:44:44
  can grow. The timing of the young star's radiation determines
• 1:44:49
  when the remaining gas gets blown away, ending the growth
• 1:44:52
  of gas giant planets. Every planetary system probably follows similar patterns,
• 1:44:59
  though the details vary depending on the mass of the star,
• 1:45:03
  the composition of the initial nebula, and random factors like
• 1:45:07
  where large planets migrate to after they form. Our solar
• 1:45:12
  system is just one example of how these formation processes
• 1:45:16
  play out. Astronomers have discovered thousands of exoplanets around other stars,
• 1:45:22
  and they show incredible diversity. There are hot Jupiters, gas
• 1:45:28
  giants that orbit closer to their stars than Mercury orbits
• 1:45:32
  our Sun. Their atmosphere is heated to thousands of degrees.
• 1:45:37
  There are super-Earths, rocky planets larger than Earth but smaller
• 1:45:42
  than Neptune, a category that doesn't exist in our solar system.
• 1:45:47
  There are planets orbiting binary star systems, experiencing double sunrises.
• 1:45:54
  There are rogue planets that don't orbit any star at all,
• 1:45:58
  ejected from their birth systems to wander the galaxy alone.
• 1:46:04
  Each of these worlds would offer its own impossible journey
• 1:46:07
  if we could fly through them. Imagine descending through a
• 1:46:10
  hot Jupiter's atmosphere, feeling temperatures climb to rival the surface
• 1:46:15
  of some stars. Imagine exploring a super-Earth with several times
• 1:46:21
  Earth's mass where gravity would crush you long before you
• 1:46:24
  reached the surface. Imagine a planet orbiting a red dwarf star,
• 1:46:30
  tidally locked, so one side always faces the star, while
• 1:46:35
  the other side faces eternal darkness. The only habitable zone,
• 1:46:40
  a narrow ring of twilight between eternal day and eternal night.
• 1:46:46
  The diversity of planets in the universe probably exceeds anything
• 1:46:49
  we've imagined so far, There might be carbon planets where
• 1:46:53
  diamond forms deep underground. There might be ocean worlds covered
• 1:46:57
  entirely by liquid water hundreds of kilometers deep. There might
• 1:47:01
  be planets with atmospheres of silicon vapor or clouds of
• 1:47:05
  molten iron rain. The universe is vast, and the possible
• 1:47:10
  combinations of temperature, pressure, composition, and gravity create environments we
• 1:47:16
  haven't begun to explore. But tonight, We focused on the
• 1:47:20
  eight planets we know best, the worlds that share our sun,
• 1:47:25
  that formed from the same cloud of gas and dust
• 1:47:29
  that created Earth. These are our siblings in a sense,
• 1:47:33
  born from the same parent nebula, shaped by the same
• 1:47:38
  physical laws, connected by the same gravitational architecture. Understanding them
• 1:47:44
  helps us understand ourselves, helps us see Earth not as
• 1:47:48
  the centre of creation but as one example of what
• 1:47:51
  planets can be. This perspective, this cosmic humility, is perhaps
• 1:47:57
  the greatest gift that planetary exploration offers. It's easy to
• 1:48:02
  think of Earth as special, unique, the only world that matters.
• 1:48:07
  And in one sense, that's true. Earth is the only
• 1:48:12
  planet we know that supports life. It's the only world
• 1:48:16
  where you can breathe the air and drink the water
• 1:48:19
  and watch sunsets that paint the sky in colours that
• 1:48:23
  exist nowhere else. But Earth is also just another planet,
• 1:48:28
  following the same laws of physics that govern Mercury and
• 1:48:31
  Jupiter and Neptune. We're not separate from the universe, we're
• 1:48:35
  part of it. The elements in our bodies came from
• 1:48:39
  stars that died billions of years ago. The water in
• 1:48:44
  our cells might have arrived on comets from the outer
• 1:48:46
  solar system. The oxygen we breathe was produced by ancient
• 1:48:51
  bacteria that transformed Earth's atmosphere from carbon dioxide to the
• 1:48:57
  nitrogen-oxygen mixture we depend on today. We exist because of
• 1:49:02
  a chain of cosmic accidents stretching back to the Big Bang.
• 1:49:07
  each link necessary, each moment building on what came before.
• 1:49:12
  Flying through every planet reminds us of this interconnectedness. The
• 1:49:17
  iron in Mercury's core might have originated in the same
• 1:49:21
  supernova explosion that created the iron in Earth's core. The
• 1:49:25
  hydrogen in Jupiter's atmosphere was forged in the first moments
• 1:49:29
  after the Big Bang, making it literally the oldest matter
• 1:49:33
  in the solar system. The methane ice on Neptune came
• 1:49:37
  from the same organic compounds that eventually led to life
• 1:49:40
  on Earth. We are all made of the same stuff,
• 1:49:44
  just arranged differently, shaped by different environments, following different evolutionary paths.
• 1:49:52
  And yet, despite these connections, each planet has developed its
• 1:49:56
  own character, its own personality almost. Mercury is the scarred veteran.
• 1:50:03
  bearing the wounds of billions of years of impacts with
• 1:50:06
  stoic endurance. Venus is the toxic beauty, gorgeous from a
• 1:50:12
  distance but deadly up close. Earth is the nurturing parent,
• 1:50:17
  providing everything life needs to flourish. Mars is the melancholy dreamer,
• 1:50:23
  remembering better days when rivers flowed and rain fell. Jupiter
• 1:50:28
  is the jovial giant, dominating the solar system with its
• 1:50:32
  mass and energy, Saturn is the elegant aristocrat, adorned with
• 1:50:37
  rings that sparkle in reflected sunlight. Uranus is the eccentric loner,
• 1:50:44
  tipped on its side, marching to its own rhythm. Neptune
• 1:50:48
  is the distant sage, cold and blue and endlessly mysterious.
• 1:50:53
  These characterizations are metaphors, of course, projections of human traits
• 1:50:58
  onto inhuman objects. Planets don't have emotions or personalities. They're
• 1:51:04
  spheres of rock and gas following orbital mechanics, shaped by
• 1:51:09
  gravity and thermodynamics and fluid dynamics. But we can't help
• 1:51:13
  anthropomorphizing them, giving them qualities that make them easier to
• 1:51:17
  relate to, easier to remember, easier to care about. And
• 1:51:21
  maybe that's not entirely wrong. Maybe seeing planets as characters
• 1:51:26
  in a cosmic drama helps us understand them better, helps
• 1:51:30
  us remember their distinctive features, helps us appreciate the narrative
• 1:51:34
  arc of how they formed and evolved. Because there is
• 1:51:39
  a story here, a genuine narrative with a beginning, middle
• 1:51:43
  and ongoing development. The solar system began as a cloud
• 1:51:48
  of gas and dust, remnants from previous generations of stars.
• 1:51:53
  Gravity caused that cloud to collapse, forming the sun at
• 1:51:57
  the centre and a disk of material around it. Within
• 1:52:02
  that disk, dust grains stuck together, building larger and larger clumps.
• 1:52:08
  These clumps collided and merged, growing into planetesimals, then protoplanets,
• 1:52:14
  then full-fledged planets. The process took millions of years, a
• 1:52:19
  violent chaotic period when impacts were common, and the young
• 1:52:24
  solar system was still finding its final configuration. Some of
• 1:52:28
  those impacts were catastrophic. The collision that created Earth's moon
• 1:52:34
  probably involved a Mars-sized object slamming into the proto-Earth, blasting
• 1:52:40
  debris into orbit that eventually coalesced into the moon. The
• 1:52:45
  impact that knocked Uranus onto its side must have been
• 1:52:48
  similarly violent, delivering so much angular momentum that the planet's
• 1:52:53
  rotation axis tilted by 98 degrees. Other impacts shaped crater-scarred
• 1:52:58
  surfaces created the enormous basins we see on Mercury and Mars,
• 1:53:04
  ejected material that became moons or rings around the giant planets. Gradually,
• 1:53:10
  over hundreds of millions of years, the solar system settled
• 1:53:14
  into relative stability. The planets cleared their orbital paths of debris.
• 1:53:21
  The gas in the inner solar system was blown away
• 1:53:24
  by solar radiation, ending the growth of the rocky planets.
• 1:53:30
  Jupiter and Saturn migrated inward and then back outward, their
• 1:53:34
  gravitational interactions reshaping the distribution of smaller bodies. The late
• 1:53:40
  heavy bombardment, a period of intense impacts about 4 billion
• 1:53:45
  years ago, scarred the surfaces of the inner planets and moons,
• 1:53:49
  before finally subsiding as the remaining debris was cleared away.
• 1:53:54
  Since then, the solar system has been relatively quiet. Planets
• 1:53:58
  orbit in their established paths. Occasional comets or asteroids still
• 1:54:03
  impact planets and moons, but nothing like the chaos of
• 1:54:06
  the early period. The sun slowly brightens as it ages,
• 1:54:11
  gradually warming the inner planets over billions of years. Jupiter
• 1:54:16
  and Saturn continue their gravitational dance, their orbits shifting slightly
• 1:54:22
  over time. The solar system is dynamic, always changing. but
• 1:54:27
  the changes now happen on timescales of millions or billions
• 1:54:32
  of years, rather than thousands. This long-term stability has allowed
• 1:54:38
  life to develop on Earth. If Jupiter's orbit was significantly different,
• 1:54:43
  it might have destabilized Earth's orbit, causing wild swings in
• 1:54:47
  climate that would have prevented complex life from evolving. If
• 1:54:52
  the late heavy bombardment had continued longer, It might have
• 1:54:55
  sterilized Earth's surface repeatedly, never giving life a chance to
• 1:55:00
  gain a foothold. If Earth was slightly closer to the
• 1:55:04
  Sun like Venus, or slightly farther away like Mars, liquid
• 1:55:09
  water might not have been stable on the surface. The
• 1:55:12
  conditions that allowed life to emerge and persist on Earth
• 1:55:16
  required a remarkable combination of factors, many of them related
• 1:55:20
  to the structure and history of the solar system as
• 1:55:23
  a whole. We're here not just because Earth is in
• 1:55:26
  the habitable zone, but because Jupiter protected us from excessive bombardment,
• 1:55:31
  because the moon stabilized our axial tilt, because plate tectonics
• 1:55:37
  recycled carbon dioxide and prevented runaway climate change, because a
• 1:55:43
  magnetic field generated by our liquid iron core deflected the
• 1:55:47
  solar wind and prevented our atmosphere from being stripped away.
• 1:55:52
  All of these factors working together created a stable environment
• 1:55:56
  where simple cells could evolve into complex organisms, where multicellular
• 1:56:01
  life could develop, where intelligence could eventually emerge. And now
• 1:56:07
  that intelligence looks outward, studying the planets that share our
• 1:56:11
  solar system, trying to understand how we fit into the
• 1:56:16
  larger cosmic story. We're the universe examining itself, matter that
• 1:56:21
  has become conscious and curious, temporary arrangements of atoms that
• 1:56:26
  somehow developed the capacity to wonder about their own origins.
• 1:56:30
  This self-reflective quality, this ability to study ourselves and our
• 1:56:35
  environment and ask deep questions about existence, might be the
• 1:56:39
  rarest thing in the universe. Life itself might be common,
• 1:56:44
  scattered across countless planets orbiting distant stars, but intelligent life
• 1:56:50
  capable of building telescopes and spacecraft and mathematical models of
• 1:56:55
  planetary interiors that might be exceedingly rare. We might be
• 1:57:01
  alone in the galaxy, the only conscious observers in a vast,
• 1:57:05
  sterile cosmos. Or there might be others, civilizations on planets
• 1:57:10
  we can't yet detect, looking up at their own skies
• 1:57:14
  and wondering if anyone else is out there. We don't know.
• 1:57:17
  We're searching, listening for radio signals from other civilizations, analysing
• 1:57:22
  the atmospheres of exoplanets for biosignatures that might indicate life.
• 1:57:27
  But so far, we've found nothing. The universe seems silent,
• 1:57:32
  empty of other voices, other minds, other explorers like us.
• 1:57:38
  This silence is called the Fermi Paradox, the apparent contradiction
• 1:57:43
  between the high probability of extraterrestrial civilisations and the complete
• 1:57:48
  lack of evidence for them. Where is everybody? Maybe we're
• 1:57:52
  the first, the earliest civilization to develop in our galaxy,
• 1:57:57
  with others yet to come. Maybe intelligence is incredibly rare,
• 1:58:01
  requiring such specific conditions that it almost never emerges. Maybe
• 1:58:07
  civilizations tend to destroy themselves shortly after developing advanced technology,
• 1:58:12
  through nuclear war or environmental collapse or artificial intelligence gone wrong.
• 1:58:18
  Maybe they're out there, but too far away for us
• 1:58:21
  to detect, separated by distances so vast that communication is impossible.
• 1:58:27
  Maybe they exist but have no interest in reaching out,
• 1:58:30
  content to observe without interfering. We don't have answers to
• 1:58:34
  these questions yet, but the search continues, and every planet
• 1:58:39
  we study, every moon we explore, adds to our understanding
• 1:58:44
  of where life might emerge and what conditions it requires.
• 1:58:49
  Europa's subsurface ocean makes it a candidate for life in
• 1:58:53
  our own solar system. Enceladus has geysers of liquid water
• 1:58:57
  erupting from its south pole, suggesting another potential habitat. Titan
• 1:59:03
  has lakes of liquid methane on its surface, and a
• 1:59:07
  thick nitrogen atmosphere that might support exotic forms of chemistry.
• 1:59:13
  Even Venus, despite its hostile surface conditions, might have habitable
• 1:59:19
  layers in its upper atmosphere where temperatures and pressures are
• 1:59:22
  more moderate. The search for life beyond Earth is one
• 1:59:26
  of the great scientific quests of our time, comparable to
• 1:59:29
  the search for the structure of DNA or the hunt
• 1:59:32
  for the Higgs boson. Finding even simple microbial life on
• 1:59:37
  another world would transform our understanding of biology and our
• 1:59:41
  place in the universe. It would tell us that life
• 1:59:45
  is not unique to Earth, that the same chemistry that
• 1:59:49
  created cells here can create cells elsewhere. that the universe
• 1:59:55
  might be teeming with living things at various stages of
• 1:59:58
  complexity and development. But even if we never find life
• 2:00:03
  beyond Earth, the journey of exploration itself has value. Learning
• 2:00:09
  about other planets helps us understand our own world better.
• 2:00:14
  Studying Venus' runaway greenhouse effect informs our understanding of climate change.
• 2:00:20
  Analysing Mars' lost atmosphere teaches us about the importance of
• 2:00:24
  magnetic fields. Observing Jupiter's complex weather systems reveals principles of
• 2:00:31
  atmospheric dynamics. Every mission, every observation, every new piece of
• 2:00:36
  data contributes to a larger understanding of how planets work.
• 2:00:41
  And there's something beautiful about that accumulation of knowledge, that
• 2:00:45
  gradual building of understanding through careful observation and rigorous analysis.
• 2:00:52
  Science is a collaborative endeavour spanning generations, with each researcher
• 2:00:58
  adding their small contribution to a growing body of knowledge.
• 2:01:03
  The work started by Galileo pointing his telescope at Jupiter,
• 2:01:07
  and discovering its moons continues today, with spacecraft orbiting that
• 2:01:12
  giant planet, measuring its magnetic field and peering into its depths.
• 2:01:18
  The observations made by early astronomers counting craters on the
• 2:01:22
  moon led eventually to spacecraft landing on Mars and driving
• 2:01:27
  across its surface. This continuity, this connection between past and
• 2:01:32
  present and future, gives scientific exploration a quality almost like storytelling.
• 2:01:39
  Each generation inherits the knowledge of previous generations and adds
• 2:01:42
  to it, passing along an ever more detailed understanding of
• 2:01:46
  the cosmos. The story isn't finished. It might never be finished.
• 2:01:51
  There will always be new questions to ask, new mysteries
• 2:01:54
  to investigate, new frontiers to explore. That's part of what
• 2:01:59
  makes science exciting. You're never done. There's always more to learn.
• 2:02:04
  And tonight, you've participated in that ongoing story. By imagining
• 2:02:10
  flying through every planet, By learning about their compositions and
• 2:02:14
  structures and histories, you've engaged with centuries of accumulated knowledge.
• 2:02:20
  You've stood on the shoulders of giants, from Copernicus, who
• 2:02:24
  realised Earth wasn't the centre of the universe, to Newton,
• 2:02:28
  who discovered the laws of gravity and motion, to Einstein,
• 2:02:32
  who showed that space and time are intertwined. to the
• 2:02:36
  countless scientists and engineers who've built and operated the missions
• 2:02:41
  that revealed these worlds to us. Your journey tonight connects
• 2:02:45
  you to all of them, makes you part of that
• 2:02:48
  long chain of curious minds reaching toward understanding. The fact
• 2:02:53
  that you've spent time learning about distant planets, imagining what
• 2:02:57
  they're like, caring enough to follow this journey to its conclusion,
• 2:03:02
  that says something important about human nature. We're explorers by instinct,
• 2:03:08
  driven to learn and discover, and push beyond known boundaries.
• 2:03:14
  That drive has taken us from caves to cities, from
• 2:03:17
  walking to flying, from Earth to the moon and beyond.
• 2:03:22
  Where that drive will take us in the future remains
• 2:03:25
  to be seen. Maybe we'll establish permanent bases on Mars,
• 2:03:30
  creating a backup for humanity in case something catastrophic happens
• 2:03:34
  to Earth. Maybe we'll mine asteroids for resources, accessing the
• 2:03:39
  vast mineral wealth of the solar system. Maybe we'll build
• 2:03:44
  space habitats, artificial worlds, where people can live without depending
• 2:03:49
  on planetary surfaces. Maybe we'll develop new propulsion systems that
• 2:03:55
  make travel to the outer planets feasible for humans. Maybe
• 2:03:59
  we'll detect signals from alien civilizations and make contact with
• 2:04:03
  other intelligent beings, or maybe none of those things will happen.
• 2:04:08
  Maybe we'll remain confined to Earth, looking outward but never leaving,
• 2:04:12
  studying the universe through telescopes and robotic proxies. Maybe we'll
• 2:04:17
  face challenges that prevent us from expanding into space, economic
• 2:04:22
  or political or environmental constraints that keep us grounded. Maybe
• 2:04:27
  humanity's future lies here on Earth, focusing on taking better
• 2:04:31
  care of our home planet rather than reaching for others.
• 2:04:34
  We don't know what the future holds, but we can
• 2:04:37
  make choices that influence that future. Choices about how we
• 2:04:42
  allocate resources, what we prioritise, what kind of civilisation we
• 2:04:47
  want to build. Do we want to be a species
• 2:04:50
  that explores and reaches outward? Or do we want to
• 2:04:53
  focus inward, solving problems here before venturing elsewhere? There's no
• 2:04:59
  obviously right answer. Both approaches have merit. Both require difficult
• 2:05:05
  trade-offs and careful consideration of competing values. What's certain is
• 2:05:10
  that the knowledge we gain from studying other planets has
• 2:05:13
  value regardless of whether we ever send humans to visit them.
• 2:05:18
  Understanding how planetary climates work helps us address climate change
• 2:05:23
  on Earth. Learning how magnetic fields protect atmospheres informs our
• 2:05:27
  understanding of space weather and radiation hazards. Studying the geology
• 2:05:33
  of other worlds reveals principles that apply to Earth as well.
• 2:05:39
  The technology developed for space missions often finds applications in medicine, communications, materials,
• 2:05:47
  science and other fields. So the investment in planetary exploration
• 2:05:53
  pays dividends even beyond the direct scientific returns. It drives innovation,
• 2:05:58
  inspires young people to pursue careers in science and engineering,
• 2:06:02
  provides a shared sense of purpose and achievement that transcends
• 2:06:06
  national boundaries. When Voyager flew past Neptune, people around the
• 2:06:11
  world watched in wonder. When rovers land on Mars, the
• 2:06:15
  images are shared globally. Space exploration is one of the
• 2:06:19
  few human endeavours that brings people together rather than dividing them.
• 2:06:25
  And on a personal level, Learning about other worlds expands
• 2:06:29
  your perspective in ways that are hard to quantify but
• 2:06:32
  deeply meaningful. Knowing that Saturn's rings are made of countless
• 2:06:36
  chunks of ice orbiting in a flat disk adds beauty
• 2:06:40
  to those images from spacecraft. Understanding that Jupiter's great red
• 2:06:45
  spot is a storm larger than Earth makes that oval
• 2:06:49
  in photographs more impressive. Realising that the surface of Venus
• 2:06:54
  is hot enough to melt lead gives weight to those
• 2:06:57
  radar maps that peer through the clouds. Each fact you learn,
• 2:07:02
  each concept you understand, enriches your experience of the universe.
• 2:07:08
  You're not just looking at pictures of distant planets. You're
• 2:07:12
  seeing worlds with histories and structures and processes that you
• 2:07:16
  can comprehend. That comprehension transforms abstract images into places that
• 2:07:23
  feel almost real, Destinations you could imagine visiting, if only
• 2:07:29
  the technology existed and the physics allowed it. We've travelled
• 2:07:34
  together through eight worlds tonight, from Mercury's scorched craters to
• 2:07:39
  Neptune's howling winds. Each planet revealed its secrets, layer by layer,
• 2:07:46
  atmosphere to core, showing us the incredible diversity our solar
• 2:07:51
  system contains. But more than facts and figures, more than
• 2:07:56
  temperatures and pressures. This journey has given us something precious,
• 2:08:01
  perspective on our place in this vast cosmic neighbourhood. The
• 2:08:05
  planets will continue spinning long after you've drifted off to sleep.
• 2:08:09
  They'll be there tomorrow, waiting under the same stars that
• 2:08:13
  have watched over Earth since before humans walked upright. And
• 2:08:18
  maybe someday, Generations from now, someone will actually fly through
• 2:08:23
  these worlds, not in imagination, but in reality, carrying forward
• 2:08:29
  the curiosity that brought you here tonight. Until then, rest well,
• 2:08:35
  cosmic explorer. The universe keeps dancing, and you've been part
• 2:08:40
  of something beautiful. I hope you had an amazing time
• 2:08:43
  with me here at Boring Science. I will see you
• 2:08:46
  tomorrow as always. Until then, Stay curious. Keep wondering. This
• 2:08:52
  is Boring Science, signing off. Cheers.