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SUB BY : DENI AUROR@
https://aurorarental.blogspot.com/
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All across our solar system,
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scientists are discovering thrilling new worlds,
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dwarf planets.
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They may be small, but they're full of riddles,
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oceans of subterranean water,
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ice volcanoes, and vanishing mountains.
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The whole idea that dwarf planets are small
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and insignificant and boring
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has just been shattered in the last few years.
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Dwarf planets defy many of the rules
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we thought governed our solar system.
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Dwarf planets are very interesting bodies
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scientifically,
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but beyond that, they tell us something
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about the origin of our own world.
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Believe it or not, they may harbor life.
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Dwarf planets are rattling the cages of scientists
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and shaking up our understanding of how the universe works.
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They may have fed the early planets
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and even seeded them with the precursors of life.
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Dwarf planets just may be the most important objects
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in the solar system.
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Our solar system has eight confirmed major planets,
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but we're discovering many other small worlds
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called dwarf planets.
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We used to think they were just dull lumps of rock,
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but the more we study them,
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the more shocking and intriguing they become.
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Naively, I would expect these objects
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to not be terribly dynamic.
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They're probably just, you know, airless, rocky, icy worlds,
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and they're just sitting there,
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and what we're finding out is that that is not true at all.
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There is all kinds of stuff going on.
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They're full worlds with really interesting geology
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and interesting histories
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that can tell us a lot about the solar system.
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Scientists believe there may be
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hundreds of dwarf planets in our solar system.
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So far, we've only identified six.
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Five of them... Pluto, with its moon, Charon;
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red-colored Sedna;
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bright, distant Eris;
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makemake, and bean-shaped Haumea...
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All live billions of miles from the Sun,
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out beyond Neptune in the Kuiper belt.
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They're just the tip of the iceberg.
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There are probably many, many more dwarf worlds
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that are out there waiting to be discovered.
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The sixth dwarf planet, Ceres,
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lives in the inner solar system.
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It orbits around 260 million miles from earth
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in the asteroid belt.
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The asteroid belt is a region of the solar system
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between Mars and Jupiter,
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and this is where most of the asteroids are.
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This is rubble
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left over from the formation of the solar system.
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In early years of the solar system,
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small rocks collided with one another, stuck together,
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and built the rocky inner planets.
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Dwarf planets grew in the same way.
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Ceres was actually starting to get pretty big.
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It was on its way to becoming a planet
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before it stopped growing, and that makes it
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stand head and shoulders above everything else there.
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So why is Ceres called a dwarf planet and not a planet?
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To be a planet, it must tick off three cosmic boxes.
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First, it needs to be a sphere.
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Second, it needs to orbit the Sun and not another body.
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Third, it needs to clear its orbital area of orbital debris.
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Ceres ticks just two of the boxes.
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It is a sphere, but a small one...
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Only 600 miles across.
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That's the size of Texas.
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It orbits the Sun, but it hasn't cleared its path of debris.
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It's surrounded by asteroids,
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so it misses out on being a planet.
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Even though we call these objects dwarf planets,
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small and dwarf does not equal insignificant.
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But being small does have its problems.
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When the molten core of a young dwarf planet cools,
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so does the heat engine that drives geologic activity.
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Ceres, we thought, would basically be a big, dead rock.
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It's a small body.
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It should have cooled off long ago.
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Nothing very interesting is going on,
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and when we actually got out to Ceres,
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nothing could have been further from the truth.
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March 2015, NASA's dawn probe arrives at Ceres.
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As the dawn spacecraft pulled up to Ceres,
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we saw the craters and the surface that we expected to see,
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and then all of a sudden,
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something totally mysterious rotated into view.
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One of the craters had two bright spots,
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almost like two eyes staring right back at us.
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It was such a puzzle to the science community
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because what are these doing here?
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Are they ice? It looks very fresh.
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What on earth could it be?
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Scientists find over 100
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of these mysterious white spots.
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The largest is in a 50-mile-wide crater called Occator.
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They are, unexpectedly,
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made up of a substance we find on earth...
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Sodium carbonate, a kind of salt.
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We believe the salts on Ceres
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as actually very young.
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We think they're as young as 4 million years old,
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and that's basically like yesterday in terms of geology.
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And that is super weird, right?
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That's happening not on sort of on a geologic era.
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It's happening now, today.
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What could cause patches of salt
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on a world long-presumed dead?
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Planetary geologist Jani Radebaugh believes a clue
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might be found at mono lake in California.
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All right, I'm here looking at this beautiful lake
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off in the distance
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and standing on massive white deposits.
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These white deposits used to be a part of this lake,
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at one point.
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The lake had dissolved a lot of the materials in it,
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and then as it receded, it left behind the materials,
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as it evaporated away,
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and these things are, you know, salts.
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They're kind of granular in texture,
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and just to make sure, we taste it
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and yeah, sure enough, it's salty.
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The salt at lake mono
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crystallizes as the water evaporates,
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the only way it can form.
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The researchers believe the same process
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is taking place on Ceres.
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This means there must be liquid water beneath the surface...
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...but how, out in the deep freeze of the asteroid belt?
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These bright spots are located in the centers of craters.
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They're located around cracks in the surface,
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and that is telling us that this material
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is coming from under the surface and welling up onto it.
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Absolutely nobody expected there to be liquid water
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beneath the surface of Ceres.
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We cannot explain what is keeping that water warm.
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On some moons,
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gravitational tugging keeps the interiors warm,
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but Ceres is not really near anything else that's very large.
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So the amazing thing is that we may not even understand
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how rocky planets work.
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There may be another source of energy,
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another mechanism for heating the interior
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that we haven't even discovered yet.
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To find out how Ceres has liquid water,
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we have to rewind the clock 4.6 billion years.
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Debris left over from the formation of the Sun
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slams together to form the dwarf planets.
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As they take shape, the heavier, rocky material
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sinks to the center and forms a hot, molten core.
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Slushy water-ice floats to the top.
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For a while, it stays liquid, but once the core cools,
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it freezes and forms the solid mantel and crust.
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That surface should still be solid,
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so the salt patches remain a perplexing mystery.
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We still haven't answered the question,
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"how could there actually still be liquid water on Ceres?"
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That's still a hard question to answer.
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One way this could happen is if it's not actually pure water,
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if you've mixed it with something else.
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Some scientists have proposed
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that a salty ocean lies beneath the surface.
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The high concentration of salt
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lowers the freezing point of the water, keeping it liquid.
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When asteroid impacts fracture the crust,
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this salty water oozes up from below.
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The liquid swiftly evaporates, but the salt remains,
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leaving a brilliant white spot on the surface.
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In fact, I'm willing to bet
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there could be water coming up now,
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bringing salts up to the surface,
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evaporating away into space,
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and that means liquid water is very close
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to the surface of Ceres right now.
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Ceres has an even more startling card up its sleeve.
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Recent research suggests that it's an immigrant.
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It didn't form anywhere near the asteroid belt.
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Ceres may have been born
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alongside hundreds of other dwarf planets,
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many billions of miles away from the Sun.
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So how did it get here?
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Most of the dwarf planets we've discovered
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lie far out in the solar system beyond the orbit of Neptune,
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but Ceres orbits between Mars and Jupiter
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in the asteroid belt.
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But its location isn't the only hint
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Ceres might be an interloper.
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Normally, celestial objects are made of the same materials
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as the other bodies in their neighborhoods,
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but that's not the case with Ceres.
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The asteroid belt is mostly made up of dry, rocky bodies
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composed of the same heavy elements
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that form the rocky inner planets.
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Ceres is very different.
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Ceres is essentially an icy world, right?
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It's made out ices instead of rocks,
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and so that's kind of weird, considering where it is.
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The ice on Ceres also contains chemical compounds
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that in the early years of the solar system,
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didn't exist in the asteroid belt.
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The more we learned about Ceres,
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the more mysterious it became.
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One of the things is that Ceres has quite a lot
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of ammonia on it, and we don't find ammonia
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anywhere near the inner part of the solar system.
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But we do find it in the outer solar system.
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We've detected ammonia on Pluto, its moon Charon,
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and out in the frozen Kuiper belt,
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where we find the other dwarf planets.
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We think that the origin of that ammonia
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would've had to be in a very cold part of the solar system,
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colder than where we find Ceres today.
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But how an icy dwarf planet with ammonia
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came to inhabit a place where ammonia can't form...
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That's a huge puzzle.
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This suggests to us that Ceres
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perhaps formed in the outer solar system
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and then migrated inwards
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to its present location in the asteroid belt.
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We used to think
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that planetary orbits were completely immutable,
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that they simply ran like clockwork
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and they didn't move around.
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Now we know that that's not the case.
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In the early stages of planet formation,
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planets move around through the gaseous disc
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that encircles the young sun,
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much like rafts that are pushed around by ocean currents.
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Ceres' ammonia suggests that dwarf planets
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rafted around on the cosmic ocean
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along with the young planets.
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Ceres is sort of a smoking gun that solar systems
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are much more dynamic, much more dramatic than we know.
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There's mounting evidence
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that Ceres formed farther out in the solar system
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and something brought this little world in.
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What could possibly have done that?
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The answer is the planet Jupiter.
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After it first formed,
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the giant planet migrated in towards the Sun.
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Its massive gravity disrupted the orbits of other bodies
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in the solar system, including that of Ceres.
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The solar system formed out of a disc of gas and dust,
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and as Jupiter formed,
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it would've been plowing through this material.
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And if it plows through that material,
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it's experiencing drag.
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As it was losing energy, it would start to move in
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toward the Sun relatively slowly.
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Ceres formed in the outer edges of the solar system.
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It was dislodged from the Kuiper belt
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and yanked inwards by the migration of Jupiter,
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and when Jupiter stopped migrating, so did Ceres.
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It settled into a new, stable orbit in the asteroid belt.
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Once you realize
265
00:14:56,280 --> 00:14:58,550
that something that strange and dramatic can happen,
266
00:14:58,550 --> 00:15:00,810
that a dwarf planet can form far out in the solar system
267
00:15:00,820 --> 00:15:02,220
and be brought in,
268
00:15:02,220 --> 00:15:04,950
it makes you wonder how many times that happened before.
269
00:15:04,950 --> 00:15:07,490
Could there have been other generations of dwarf planets
270
00:15:07,490 --> 00:15:09,090
that got thrown in towards the Sun
271
00:15:09,090 --> 00:15:11,490
or maybe were thrown out of the solar system entirely?
272
00:15:17,030 --> 00:15:20,170
Scientists believe that squadrons of rocks
273
00:15:20,170 --> 00:15:21,900
and icy dwarf planets
274
00:15:21,900 --> 00:15:24,910
may have hurdled into the solar system.
275
00:15:24,910 --> 00:15:26,710
Hundreds set out.
276
00:15:26,710 --> 00:15:28,980
Only one survived.
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00:15:28,980 --> 00:15:31,250
If there was a population
278
00:15:31,250 --> 00:15:32,710
of small dwarf planets
279
00:15:32,710 --> 00:15:35,320
in the outer solar system that migrated inwards,
280
00:15:35,320 --> 00:15:39,050
Ceres might be the sole survivor, the only one left.
281
00:15:39,060 --> 00:15:41,660
So if Ceres settled into its new home
282
00:15:41,660 --> 00:15:43,120
in the asteroid belt,
283
00:15:43,130 --> 00:15:46,860
where are the rest of the icy worlds and the water on them?
284
00:15:46,860 --> 00:15:49,000
The idea that Ceres may have moved in
285
00:15:49,000 --> 00:15:50,730
from the outer solar system is interesting,
286
00:15:50,730 --> 00:15:52,600
but why should it be important to you?
287
00:15:52,600 --> 00:15:55,670
And incredibly, the answer might be inside your own body
288
00:15:55,670 --> 00:15:56,870
right now.
289
00:15:56,870 --> 00:15:58,740
For the longest time, we've wondered
290
00:15:58,740 --> 00:16:01,540
where did the majority of earth's water come from?
291
00:16:01,540 --> 00:16:03,280
When you think about where the earth is,
292
00:16:03,280 --> 00:16:04,810
how close it is to the Sun,
293
00:16:04,810 --> 00:16:06,480
there shouldn't have been any water here.
294
00:16:09,820 --> 00:16:11,890
Understanding the evolution of Ceres,
295
00:16:11,890 --> 00:16:16,020
from where it formed to where we find it today,
296
00:16:16,030 --> 00:16:18,960
could also lead us to understand how the earth can end up
297
00:16:18,960 --> 00:16:21,760
with more water than we would otherwise expect.
298
00:16:21,760 --> 00:16:23,830
When the earth formed,
299
00:16:23,830 --> 00:16:26,630
it was too hot for water to exist on the surface.
300
00:16:26,640 --> 00:16:29,840
Perhaps the squadrons of dwarf planets
301
00:16:29,840 --> 00:16:31,510
broke up on their journey,
302
00:16:31,510 --> 00:16:35,380
showering earth with water-rich lumps of rock,
303
00:16:35,380 --> 00:16:38,240
enough to fill earth's oceans.
304
00:16:38,250 --> 00:16:41,250
Amazingly, when we study the chemistry of water,
305
00:16:41,250 --> 00:16:44,990
the best match is that the water in your body right now
306
00:16:44,990 --> 00:16:46,990
came from asteroids themselves,
307
00:16:46,990 --> 00:16:49,520
asteroids and dwarf planets that rained down
308
00:16:49,530 --> 00:16:52,730
and hit the earth over billions of years.
309
00:16:52,730 --> 00:16:56,530
Dwarf planets may have brought something else.
310
00:16:56,530 --> 00:17:00,670
February 2017, scientists announce
311
00:17:00,670 --> 00:17:03,540
the discovery of organic materials
312
00:17:03,540 --> 00:17:05,410
on the surface of Ceres.
313
00:17:05,410 --> 00:17:07,540
On earth, life uses water
314
00:17:07,540 --> 00:17:10,340
and organic chemistry, carbon-based molecules.
315
00:17:10,350 --> 00:17:12,810
The intriguing thing about the dwarf planets
316
00:17:12,810 --> 00:17:14,420
is that they have both of those.
317
00:17:14,420 --> 00:17:16,620
Pluto and Ceres have organic molecules.
318
00:17:16,620 --> 00:17:18,620
There's liquid water below the surface.
319
00:17:18,620 --> 00:17:21,290
There's a source of energy that warms the interior.
320
00:17:21,290 --> 00:17:24,160
It is not at all impossible that somewhere under
321
00:17:24,160 --> 00:17:27,760
these cold, icy surfaces, there could be life.
322
00:17:27,760 --> 00:17:30,900
Could other dwarf planets host life, too?
323
00:17:30,900 --> 00:17:36,040
Sedna and makemake both have red-colored patches.
324
00:17:36,040 --> 00:17:38,970
The color comes from something called tholins,
325
00:17:38,970 --> 00:17:43,440
organic molecules that could be a precursor to life.
326
00:17:43,450 --> 00:17:46,310
Based on all the interesting chemistry they're doing,
327
00:17:46,320 --> 00:17:48,180
these dwarf planets could be like
328
00:17:48,180 --> 00:17:49,550
the test tubes of the solar system.
329
00:17:53,460 --> 00:17:57,120
If there are small bodies strewn all about the solar system
330
00:17:57,130 --> 00:17:59,990
that had liquid water or ice,
331
00:18:00,000 --> 00:18:02,460
it could possibly serve as an Incubator for life,
332
00:18:02,460 --> 00:18:04,000
just holding on to it,
333
00:18:04,000 --> 00:18:06,470
ready to crash into another body and seed it.
334
00:18:06,470 --> 00:18:08,670
The habitable zone now extends
335
00:18:08,670 --> 00:18:10,000
to the entire solar system.
336
00:18:10,010 --> 00:18:13,070
It really expands... It greatly expands...
337
00:18:13,080 --> 00:18:15,940
The stage for the play of life in the entire galaxy.
338
00:18:15,950 --> 00:18:19,350
Maybe we have dwarf planets to thank
339
00:18:19,350 --> 00:18:20,910
for our very existence.
340
00:18:20,920 --> 00:18:24,480
All of a sudden, the smallest bodies in our solar system
341
00:18:24,490 --> 00:18:26,820
have become some of the most interesting things
342
00:18:26,820 --> 00:18:28,160
we've ever seen.
343
00:18:28,160 --> 00:18:32,030
The idea of migrating dwarf planets
344
00:18:32,030 --> 00:18:35,500
opens up some intriguing scenarios,
345
00:18:35,500 --> 00:18:39,370
including one really out-there possibility.
346
00:18:39,370 --> 00:18:42,500
Some of that water and organic material
347
00:18:42,510 --> 00:18:45,240
may not be from our solar system.
348
00:19:05,330 --> 00:19:08,930
The more we learn about dwarf planets,
349
00:19:08,930 --> 00:19:11,000
the more they surprise us.
350
00:19:20,210 --> 00:19:22,210
But there's one dwarf planet
351
00:19:22,210 --> 00:19:24,880
whose very existence is a mystery.
352
00:19:24,880 --> 00:19:29,550
It's called Sedna, and no one is quite sure
353
00:19:29,550 --> 00:19:32,350
what it's doing in our solar system.
354
00:19:32,350 --> 00:19:35,960
Sedna may have my vote for the single most peculiar object
355
00:19:35,960 --> 00:19:38,160
in the entire solar system.
356
00:19:38,160 --> 00:19:41,830
Here, we have a world which is about 1,000 miles wide,
357
00:19:41,830 --> 00:19:47,300
but it is way far out in the solar system, way past Neptune.
358
00:19:49,570 --> 00:19:51,570
Sedna is the most distant object
359
00:19:51,570 --> 00:19:54,370
we've identified in our solar system.
360
00:19:54,380 --> 00:19:56,110
Standing on the surface of Sedna,
361
00:19:56,110 --> 00:19:58,380
looking back at the solar system,
362
00:19:58,380 --> 00:20:01,110
the Sun would look like a really bright star,
363
00:20:01,120 --> 00:20:03,520
but not much more than a really bright star.
364
00:20:06,660 --> 00:20:08,660
Just like Pluto,
365
00:20:08,660 --> 00:20:12,330
Sedna has a strange, elliptical orbit.
366
00:20:12,330 --> 00:20:16,400
The difference is, Sedna travels from 7 billion
367
00:20:16,400 --> 00:20:19,530
to 93 billion miles from the Sun,
368
00:20:19,530 --> 00:20:24,000
and unlike Pluto, its orbit can't be explained
369
00:20:24,010 --> 00:20:26,340
by its close proximity to Neptune.
370
00:20:29,680 --> 00:20:32,350
The weird thing about Sedna is its orbit.
371
00:20:32,350 --> 00:20:34,380
How could it have gotten that elliptical
372
00:20:34,380 --> 00:20:37,750
when it's that far away from any of the major planets?
373
00:20:37,750 --> 00:20:40,020
If you have an object that's close enough to Neptune,
374
00:20:40,020 --> 00:20:42,020
Neptune's gravity can affect its orbit
375
00:20:42,020 --> 00:20:44,020
and swing it into an elliptical orbit.
376
00:20:44,030 --> 00:20:47,430
The problem is, Sedna never gets that close to Neptune.
377
00:20:47,430 --> 00:20:48,830
It doesn't get anywhere near close enough
378
00:20:48,830 --> 00:20:50,230
to be in that kind of orbit,
379
00:20:50,230 --> 00:20:53,630
and that means that something else is going on out there.
380
00:20:58,440 --> 00:21:00,710
Sedna cannot be explained
381
00:21:00,710 --> 00:21:02,380
using objects that we know.
382
00:21:02,380 --> 00:21:04,180
Everything else, we can understand
383
00:21:04,180 --> 00:21:06,110
why its where it is based on, you know,
384
00:21:06,120 --> 00:21:08,720
the eight planets and many, many other small bodies.
385
00:21:08,720 --> 00:21:10,780
Sedna cannot be explained by that,
386
00:21:10,790 --> 00:21:13,390
and, you know, that's the sign of a good mystery.
387
00:21:13,390 --> 00:21:15,720
Something else must have happened.
388
00:21:18,390 --> 00:21:20,790
Looking at models for how you can change
389
00:21:20,800 --> 00:21:22,800
the orbits of objects, there's almost no way
390
00:21:22,800 --> 00:21:25,530
Sedna could've formed in our solar system,
391
00:21:25,530 --> 00:21:28,670
and then had its orbit change so that it's that elliptical
392
00:21:28,670 --> 00:21:30,600
and goes that far out from the Sun.
393
00:21:30,610 --> 00:21:35,280
And that means maybe... Maybe... it didn't form here.
394
00:21:35,280 --> 00:21:37,210
It may be an alien world.
395
00:21:50,020 --> 00:21:52,230
How could our solar system
396
00:21:52,230 --> 00:21:55,960
have snagged an alien world?
397
00:21:55,960 --> 00:21:58,700
Long ago, it turns out our sun
398
00:21:58,700 --> 00:22:03,370
may have rubbed cosmic shoulders with other stars.
399
00:22:03,370 --> 00:22:07,910
It was born in a stellar nursery...
400
00:22:07,910 --> 00:22:10,710
Close to many other embryonic stars.
401
00:22:12,720 --> 00:22:16,320
So if the Sun was born in a very dense neighborhood,
402
00:22:16,320 --> 00:22:18,180
whereby a lot of other stars
403
00:22:18,190 --> 00:22:20,250
were forming at the same time in the same region,
404
00:22:20,260 --> 00:22:23,190
it is absolutely possible that material could be exchanged
405
00:22:23,190 --> 00:22:26,130
between these stars as they're forming planets.
406
00:22:26,130 --> 00:22:29,000
Sedna may have formed just like any other object
407
00:22:29,000 --> 00:22:31,800
around another star... In a nice, circular orbit
408
00:22:31,800 --> 00:22:35,070
out past the main planets of that alien solar system,
409
00:22:35,070 --> 00:22:37,670
but if that star got close enough to the Sun,
410
00:22:37,670 --> 00:22:42,410
our gravity may have been able to lift Sedna out and steal it.
411
00:22:46,550 --> 00:22:49,280
It's possible that other dwarf planets
412
00:22:49,280 --> 00:22:52,220
were abducted from other systems
413
00:22:52,220 --> 00:22:56,420
and that these alien worlds carried alien water
414
00:22:56,430 --> 00:23:01,160
and even alien organic materials to the inner planets.
415
00:23:03,970 --> 00:23:06,900
It's so tempting to think that we understand something
416
00:23:06,900 --> 00:23:09,700
as basic as our own solar system, our own home.
417
00:23:09,700 --> 00:23:11,700
When you discover something like Sedna,
418
00:23:11,710 --> 00:23:14,640
you realize there could be a lot out there that we haven't seen.
419
00:23:14,640 --> 00:23:16,980
There are objects that are small like Sedna
420
00:23:16,980 --> 00:23:18,380
that are just so far away
421
00:23:18,380 --> 00:23:20,650
that they're beyond our limit to detect them,
422
00:23:20,650 --> 00:23:24,120
so there could be hundreds, thousands, tens of thousands
423
00:23:24,120 --> 00:23:27,050
of objects out there, new parts of our solar system
424
00:23:27,060 --> 00:23:28,920
that are still waiting to be discovered.
425
00:23:31,390 --> 00:23:33,990
Our understanding of the solar system
426
00:23:34,000 --> 00:23:35,400
is changing radically.
427
00:23:35,400 --> 00:23:39,070
Newly explored dwarf planets stun us,
428
00:23:39,070 --> 00:23:43,940
and even the most famous one, Pluto, reveals new secrets...
429
00:23:46,340 --> 00:23:48,340
...making us ask,
430
00:23:48,340 --> 00:23:53,280
could these worlds be as active...
431
00:23:53,280 --> 00:23:56,080
And alive as our own?
432
00:24:11,100 --> 00:24:13,770
Dwarf planets all over the solar system
433
00:24:13,770 --> 00:24:17,100
are revealing hidden lives.
434
00:24:17,110 --> 00:24:20,770
In the asteroid belt, salt on the surface of Ceres
435
00:24:20,780 --> 00:24:24,980
suggests liquid water beneath the surface.
436
00:24:24,980 --> 00:24:27,710
Farther out, the new horizons mission
437
00:24:27,720 --> 00:24:31,790
found subsurface oceans on Pluto.
438
00:24:31,790 --> 00:24:33,790
We used to think that water could only exist
439
00:24:33,790 --> 00:24:35,190
in this Goldilocks zone,
440
00:24:35,190 --> 00:24:37,460
where it's not so hot that the water boils off
441
00:24:37,460 --> 00:24:39,660
and it's not so cold that it freezes,
442
00:24:39,660 --> 00:24:41,790
but that's not the case anymore.
443
00:24:41,800 --> 00:24:43,800
We look around, and we find water
444
00:24:43,800 --> 00:24:46,870
in the most unexpected places in our own solar system.
445
00:24:46,870 --> 00:24:49,140
This is kind of a revelation
446
00:24:49,140 --> 00:24:50,470
of modern planetary science
447
00:24:50,470 --> 00:24:52,810
that so many of these worlds in the outer solar system
448
00:24:52,810 --> 00:24:55,680
may have subsurface oceans of liquid water.
449
00:24:55,680 --> 00:24:58,680
It kind of boggles the mind to see how far we've come
450
00:24:58,680 --> 00:24:59,880
in our understanding
451
00:24:59,880 --> 00:25:03,280
of the interior structures of these worlds.
452
00:25:03,290 --> 00:25:06,820
Finding liquid water so far from the Sun
453
00:25:06,820 --> 00:25:08,960
left scientists stunned...
454
00:25:10,960 --> 00:25:13,760
...and the surprises keep on coming
455
00:25:13,760 --> 00:25:17,960
as we study these distant worlds up close.
456
00:25:17,970 --> 00:25:22,300
Makemake, 2/3 the size of Pluto.
457
00:25:22,300 --> 00:25:28,110
Its surface is covered in ethane and methane ice.
458
00:25:28,110 --> 00:25:32,310
The methane is frozen into 1/2-inch-sized ice grains.
459
00:25:32,310 --> 00:25:37,980
It reacts with sunlight, forming organic molecules call tholins.
460
00:25:37,990 --> 00:25:41,050
These color the planet red-brown.
461
00:25:43,390 --> 00:25:46,130
Farther out lies Eris.
462
00:25:46,130 --> 00:25:48,530
It's 9 billion miles from the Sun,
463
00:25:48,530 --> 00:25:50,260
and its surface temperature...
464
00:25:50,260 --> 00:25:55,330
About 400 degrees Fahrenheit below zero.
465
00:25:55,340 --> 00:25:57,940
Eris is an absolutely tantalizing object.
466
00:25:57,940 --> 00:25:59,940
We really don't know much about it at all.
467
00:25:59,940 --> 00:26:02,340
It should be very similar to Pluto,
468
00:26:02,340 --> 00:26:03,680
but one of the things we notice
469
00:26:03,680 --> 00:26:05,810
is that Pluto's surface is kind of patchy.
470
00:26:05,810 --> 00:26:07,610
There are areas that are very bright,
471
00:26:07,620 --> 00:26:10,080
but also areas that are quite dark.
472
00:26:10,090 --> 00:26:13,750
Eris, on the other hand, seems to be almost entirely bright.
473
00:26:18,030 --> 00:26:20,490
Eris is one of the shiniest objects
474
00:26:20,500 --> 00:26:21,630
in the solar system,
475
00:26:21,630 --> 00:26:25,570
reflecting 96% of the light that hits it.
476
00:26:25,570 --> 00:26:27,300
Scientists wondered why.
477
00:26:27,300 --> 00:26:33,310
A clue comes from its near neighbor, Pluto.
478
00:26:33,310 --> 00:26:38,710
When new horizons flew past, it spotted something strange.
479
00:26:38,710 --> 00:26:42,250
One of the funny little details is that as we flew over Pluto,
480
00:26:42,250 --> 00:26:43,580
we realized that there were things
481
00:26:43,590 --> 00:26:46,120
that looked a lot like sand dunes down there.
482
00:26:46,120 --> 00:26:48,250
Now, that may not sound incredibly exotic.
483
00:26:48,260 --> 00:26:51,120
You know, what's very interesting about a sand dune?
484
00:26:51,130 --> 00:26:53,990
Sand dunes may sound dull,
485
00:26:54,000 --> 00:26:58,530
but they can reveal a lot about the mechanics of a planet.
486
00:26:58,530 --> 00:27:01,070
Unlike the dunes we know and love on the earth
487
00:27:01,070 --> 00:27:02,870
that are made of sand, the dunes on Pluto
488
00:27:02,870 --> 00:27:05,140
are made entirely of particles of ice.
489
00:27:07,940 --> 00:27:12,610
There's only one thing that can build dunes... wind.
490
00:27:14,820 --> 00:27:17,750
Dunes are like a visual representation of the wind
491
00:27:17,750 --> 00:27:21,020
that's moving across the valley and carrying the sands with it
492
00:27:21,020 --> 00:27:24,490
and depositing it into these big, beautiful dune forms.
493
00:27:26,360 --> 00:27:28,360
Our planet is large enough
494
00:27:28,360 --> 00:27:30,900
to hold on to an atmosphere.
495
00:27:30,900 --> 00:27:35,370
Air, warmed by the Sun, rises.
496
00:27:35,370 --> 00:27:39,910
Fresh air rushes in underneath, generating winds.
497
00:27:39,910 --> 00:27:43,040
Pluto is so small and so far from the Sun,
498
00:27:43,050 --> 00:27:47,910
it shouldn't have an atmosphere or wind or dunes.
499
00:27:47,920 --> 00:27:49,050
The problem Pluto has,
500
00:27:49,050 --> 00:27:51,180
like other small bodies in the solar system,
501
00:27:51,190 --> 00:27:53,590
is that it's really hard for it to hold on to an atmosphere.
502
00:27:53,590 --> 00:27:55,120
It's just too small.
503
00:27:55,120 --> 00:27:59,530
The very thin, light atmospheric gases basically just escape.
504
00:27:59,530 --> 00:28:02,130
Neither Haumea nor makemake
505
00:28:02,130 --> 00:28:05,330
have detectable atmospheres,
506
00:28:05,330 --> 00:28:08,540
but when new horizons looked back at Pluto
507
00:28:08,540 --> 00:28:12,140
as the dwarf planet passed in front of the Sun,
508
00:28:12,140 --> 00:28:17,740
scientists spotted a thin haze of gas.
509
00:28:17,750 --> 00:28:20,950
Turns out, Pluto has an atmosphere.
510
00:28:24,150 --> 00:28:26,750
But this atmosphere is temporary
511
00:28:26,760 --> 00:28:30,420
because Pluto's orbit is elliptical.
512
00:28:30,420 --> 00:28:32,560
Some of the time, it's far from the Sun.
513
00:28:32,560 --> 00:28:35,630
Other times, it's much closer and warmer,
514
00:28:35,630 --> 00:28:38,630
creating a kind of winter and summer.
515
00:28:40,970 --> 00:28:43,370
Pluto's atmosphere depends on the season.
516
00:28:43,370 --> 00:28:45,570
In the summer, it's warm enough to have an atmosphere,
517
00:28:45,570 --> 00:28:49,980
and in the winter, that atmosphere freezes out.
518
00:28:49,980 --> 00:28:52,310
Over the course of just a single orbit around the Sun,
519
00:28:52,310 --> 00:28:53,980
the surfaces of these dwarf planets
520
00:28:53,980 --> 00:28:55,720
may change significantly,
521
00:28:55,720 --> 00:28:57,650
condensing and coding out atmosphere
522
00:28:57,650 --> 00:28:59,450
when they're far from the Sun,
523
00:28:59,450 --> 00:29:01,790
having that atmosphere revolatilize
524
00:29:01,790 --> 00:29:06,390
and redistribute the surface when they're closer to the Sun.
525
00:29:06,390 --> 00:29:09,260
Pluto is currently in its summer phase.
526
00:29:09,260 --> 00:29:12,200
The extra heat during the long super summer
527
00:29:12,200 --> 00:29:16,470
evaporates some of the nitrogen ice on the surface,
528
00:29:16,470 --> 00:29:20,410
creating a thin, wispy atmosphere.
529
00:29:20,410 --> 00:29:22,080
It turns out that even though
530
00:29:22,080 --> 00:29:25,480
the atmosphere of Pluto is very thin, there is wind.
531
00:29:25,480 --> 00:29:28,480
It's really light, but there's just enough wind
532
00:29:28,480 --> 00:29:33,020
to be able to carry particles with it once they start moving.
533
00:29:33,020 --> 00:29:35,020
The seasonal cycle
534
00:29:35,020 --> 00:29:39,230
could help explain Eris' brightness.
535
00:29:39,230 --> 00:29:42,300
Eris is three times further away from the Sun
536
00:29:42,300 --> 00:29:43,430
than Pluto is,
537
00:29:43,430 --> 00:29:44,960
but when you put a nitrogen atmosphere
538
00:29:44,970 --> 00:29:46,700
three times further away,
539
00:29:46,700 --> 00:29:50,100
that nitrogen freezes solid to the surface.
540
00:29:50,110 --> 00:29:52,040
Eris could be an indicator
541
00:29:52,040 --> 00:29:54,370
of what Pluto looks like when it enters its winter.
542
00:29:54,380 --> 00:29:57,980
The gases will freeze, and it'll become even more reflective.
543
00:29:59,980 --> 00:30:01,510
In winter,
544
00:30:01,520 --> 00:30:05,580
Pluto's dunes will be locked in place...
545
00:30:05,590 --> 00:30:07,990
Frozen on the surface,
546
00:30:07,990 --> 00:30:12,990
unlike the icy features of another dwarf planet
547
00:30:12,990 --> 00:30:16,400
and the case of the vanishing volcanoes.
548
00:30:34,350 --> 00:30:37,280
From afar, the dwarf planet Ceres
549
00:30:37,290 --> 00:30:39,220
looks uniform and dull...
550
00:30:41,420 --> 00:30:46,490
...but up close, one huge feature comes into view.
551
00:30:46,490 --> 00:30:48,290
One of the strangest objects that we saw
552
00:30:48,300 --> 00:30:50,430
when we began to map the surface of Ceres
553
00:30:50,430 --> 00:30:54,230
was something called Ahuna Mons.
554
00:30:54,240 --> 00:30:58,300
Now, this was a strange, jutting hill, very, very sharp sides,
555
00:30:58,310 --> 00:31:01,640
and it didn't match any of the other terrain on Ceres.
556
00:31:01,640 --> 00:31:06,450
Ahuna Mons is a very peculiar feature on Ceres.
557
00:31:06,450 --> 00:31:09,720
This is a mountain that is standing three miles high,
558
00:31:09,720 --> 00:31:11,320
and there's nothing else like it
559
00:31:11,320 --> 00:31:14,720
on the entire surface of Ceres.
560
00:31:14,720 --> 00:31:18,990
Ahuna Mons dominates the landscape of Ceres.
561
00:31:18,990 --> 00:31:21,930
With its steep sides and enormous height,
562
00:31:21,930 --> 00:31:24,800
it looks a lot like volcanoes on earth,
563
00:31:24,800 --> 00:31:28,330
but earth is still geologically active.
564
00:31:28,340 --> 00:31:33,410
Ceres is so small, its molten core should be frozen solid.
565
00:31:37,880 --> 00:31:40,010
Planetary scientist Nina Lanza
566
00:31:40,010 --> 00:31:43,150
heads to one of the most volcanically active places
567
00:31:43,150 --> 00:31:44,950
on earth... Iceland.
568
00:31:47,290 --> 00:31:50,220
She has a drone's-eye view of mount Helgafell,
569
00:31:50,230 --> 00:31:53,830
a volcano similar in shape to Ahuna Mons.
570
00:31:56,160 --> 00:31:59,700
So this volcano is what's called a rhyolitic dome,
571
00:31:59,700 --> 00:32:02,500
and so it's a type of lava
572
00:32:02,500 --> 00:32:05,770
that kind of gets squeezed out through fissures,
573
00:32:05,770 --> 00:32:10,440
and then forms this kind of blobby dome feature
574
00:32:10,450 --> 00:32:13,980
that gets pushed up by the magma coming up from beneath.
575
00:32:16,320 --> 00:32:19,590
On earth, red-hot magma bubbles slowly
576
00:32:19,590 --> 00:32:23,660
out of cracks in the surface, building a steep-sided volcano.
577
00:32:25,860 --> 00:32:28,660
But dwarf planets like Ceres are too small
578
00:32:28,660 --> 00:32:32,600
to have a hot core of molten rock to power volcanism.
579
00:32:34,940 --> 00:32:37,700
There isn't molten rock on these smaller worlds
580
00:32:37,710 --> 00:32:38,940
that have a lot of ice on them.
581
00:32:38,940 --> 00:32:42,780
Instead, what's molten is water under the surface,
582
00:32:42,780 --> 00:32:45,210
and if the water can work its way up through cracks
583
00:32:45,210 --> 00:32:48,350
and erupt out in the surface, you get a volcano.
584
00:32:48,350 --> 00:32:51,880
But it's a cold-water volcano.
585
00:32:51,890 --> 00:32:55,960
We call these cryovolcanoes.
586
00:32:55,960 --> 00:32:58,160
Liquid water squeezes up
587
00:32:58,160 --> 00:33:00,630
through fissures in the surface.
588
00:33:00,630 --> 00:33:04,900
It quickly freezes, building the mountain.
589
00:33:04,900 --> 00:33:09,170
This volcano, you can see that it's a pretty young feature,
590
00:33:09,170 --> 00:33:11,840
and it's not very eroded.
591
00:33:11,840 --> 00:33:15,640
We expect on earth that wind and water
592
00:33:15,640 --> 00:33:18,110
will slowly erode this mountain away.
593
00:33:18,110 --> 00:33:20,110
With no wind or weather
594
00:33:20,110 --> 00:33:24,050
to erode Ceres' cryovolcanoes, once created,
595
00:33:24,050 --> 00:33:26,120
they should remain on the surface
596
00:33:26,120 --> 00:33:29,790
for billions of years.
597
00:33:29,790 --> 00:33:31,960
Ahuna Mons is very strange
598
00:33:31,960 --> 00:33:34,730
because it's the only tall mountain on Ceres.
599
00:33:34,730 --> 00:33:35,930
Why should that be?
600
00:33:35,930 --> 00:33:38,460
You don't typically get just one of something.
601
00:33:38,470 --> 00:33:40,930
You should have dozens of them, and, in fact,
602
00:33:40,940 --> 00:33:44,800
Ceres may have had quite a few cryovolcanoes in the past,
603
00:33:44,810 --> 00:33:47,340
but they're all gone today.
604
00:33:47,340 --> 00:33:48,810
Just to put that into perspective,
605
00:33:48,810 --> 00:33:51,880
imagine if this is the only mountain on earth.
606
00:33:51,880 --> 00:33:53,410
Why would there only be one mountain?
607
00:33:53,420 --> 00:33:54,610
What would that mean?
608
00:33:54,620 --> 00:33:56,680
This leads us to ask the question, you know,
609
00:33:56,680 --> 00:34:01,150
are the volcanoes on Ceres disappearing?
610
00:34:01,160 --> 00:34:03,890
The idea that volcanoes are vanishing...
611
00:34:03,890 --> 00:34:06,630
It just sounds totally science fiction,
612
00:34:06,630 --> 00:34:08,560
and really, not realistic at all.
613
00:34:08,560 --> 00:34:10,900
Of course, volcanoes can't just vanish,
614
00:34:10,900 --> 00:34:13,500
but actually, in the right context,
615
00:34:13,500 --> 00:34:15,970
in certain scenarios, they actually can.
616
00:34:17,910 --> 00:34:20,910
The key to this magic trick... Gravity.
617
00:34:20,910 --> 00:34:22,910
It can flatten solid matter.
618
00:34:22,910 --> 00:34:24,980
How quickly depends on
619
00:34:24,980 --> 00:34:28,750
the structural composition of the material.
620
00:34:28,750 --> 00:34:30,980
If you want to build a sand castle on the beach,
621
00:34:30,990 --> 00:34:32,250
you can't use dry sand.
622
00:34:32,250 --> 00:34:33,520
It doesn't stick together,
623
00:34:33,520 --> 00:34:35,320
so you want to mix a little bit of water in there
624
00:34:35,320 --> 00:34:37,260
so that when you make the structure,
625
00:34:37,260 --> 00:34:38,720
it holds together,
626
00:34:38,730 --> 00:34:41,930
but if you mix in too much water, it just dribbles away.
627
00:34:41,930 --> 00:34:43,660
It viscously relaxes.
628
00:34:43,670 --> 00:34:45,760
It slumps.
629
00:34:45,770 --> 00:34:48,730
Even Iceland's rock volcanoes
630
00:34:48,740 --> 00:34:52,210
are slowly slumping under their own weight.
631
00:34:52,210 --> 00:34:54,470
Strange as it is to imagine this,
632
00:34:54,480 --> 00:34:56,210
it turns out the mountain behind me
633
00:34:56,210 --> 00:35:00,210
is actually slowly relaxing back down.
634
00:35:00,220 --> 00:35:01,950
It's just happening very slowly,
635
00:35:01,950 --> 00:35:05,950
not on a time scale that we can directly observe.
636
00:35:05,950 --> 00:35:09,820
It may be that there were many cryovolcanoes
637
00:35:09,820 --> 00:35:11,090
on the surface of Ceres.
638
00:35:11,090 --> 00:35:14,830
They no longer show any trace of their existence...
639
00:35:14,830 --> 00:35:17,030
So if we waited around a little bit longer
640
00:35:17,030 --> 00:35:19,230
until all of Ahuna Mons had slowly relaxed
641
00:35:19,230 --> 00:35:23,640
back into the planet, we'd see no trace of it, either.
642
00:35:23,640 --> 00:35:27,970
Maybe Ahuna Mons hasn't always stood alone.
643
00:35:27,980 --> 00:35:31,580
Maybe it's just the last of its kind.
644
00:35:31,580 --> 00:35:34,980
Ceres continues to confound our expectations,
645
00:35:34,980 --> 00:35:37,450
and there are still many mysteries
646
00:35:37,450 --> 00:35:39,990
with the other dwarf planets to be solved,
647
00:35:39,990 --> 00:35:42,990
such as how they got their moons
648
00:35:42,990 --> 00:35:46,330
and why Pluto lies on its side.
649
00:36:04,580 --> 00:36:06,610
Just like their larger cousins,
650
00:36:06,610 --> 00:36:11,020
dwarf planets often have orbiting satellites.
651
00:36:11,020 --> 00:36:16,160
We now realize that all of the largest dwarf planets
652
00:36:16,160 --> 00:36:18,360
have moons around them, have a moon.
653
00:36:18,360 --> 00:36:20,560
Most of them have one. Haumea has two.
654
00:36:20,560 --> 00:36:23,900
Pluto has five.
655
00:36:23,900 --> 00:36:25,960
Four billion years ago,
656
00:36:25,970 --> 00:36:28,570
the young solar system was chaotic,
657
00:36:28,570 --> 00:36:31,570
filled with small bodies orbiting the Sun.
658
00:36:33,710 --> 00:36:39,310
One hit the infant earth, forming the moon.
659
00:36:39,310 --> 00:36:44,250
Smash-ups like these happened throughout the solar system.
660
00:36:44,250 --> 00:36:48,590
The dwarf planet Haumea formed from an explosive collision
661
00:36:48,590 --> 00:36:52,390
between two larger objects...
662
00:36:52,390 --> 00:36:57,400
Which may account for its unusual bean-like shape.
663
00:36:57,400 --> 00:37:01,470
All the dwarf planets suffered huge impacts.
664
00:37:01,470 --> 00:37:03,400
Haumea had this big one that left it spinning.
665
00:37:03,400 --> 00:37:05,970
Eris has a tiny moon, presumably from a giant impact.
666
00:37:05,970 --> 00:37:07,470
Makemake has one.
667
00:37:07,470 --> 00:37:11,940
All these biggest objects have these tiny fragments of moons
668
00:37:11,950 --> 00:37:14,750
showing us their history of just getting battered
669
00:37:14,750 --> 00:37:18,620
and pieces being knocked off everywhere.
670
00:37:18,620 --> 00:37:21,550
Most dwarf planets' moons are tiny,
671
00:37:21,560 --> 00:37:24,760
not much bigger than asteroids,
672
00:37:24,760 --> 00:37:27,760
but one moon is very different...
673
00:37:27,760 --> 00:37:31,230
Pluto's moon, Charon.
674
00:37:31,230 --> 00:37:36,640
Pluto's moon is, if anything, weirder than Pluto itself.
675
00:37:36,640 --> 00:37:37,840
It's Frankenstein's moon.
676
00:37:37,840 --> 00:37:39,710
It looks like somebody tore a moon apart
677
00:37:39,710 --> 00:37:42,240
and then just kind of slapdashed it back together.
678
00:37:42,240 --> 00:37:43,840
One hemisphere is smooth.
679
00:37:43,840 --> 00:37:45,440
One is very rugged.
680
00:37:45,450 --> 00:37:49,050
It's got a canyon that's like a notched carved out of the side.
681
00:37:49,050 --> 00:37:52,850
It is really bizarre.
682
00:37:52,850 --> 00:37:55,320
An impact may have formed Charon
683
00:37:55,320 --> 00:37:57,590
and left it tied to Pluto
684
00:37:57,590 --> 00:38:00,130
in an oddly codependent relationship.
685
00:38:00,130 --> 00:38:01,930
In some ways, you can think of
686
00:38:01,930 --> 00:38:05,060
the Pluto-Charon system as almost a binary planet.
687
00:38:05,070 --> 00:38:07,130
There is no other planet in the solar system
688
00:38:07,130 --> 00:38:11,740
where the moon is so large in proportion to it and so close.
689
00:38:11,740 --> 00:38:13,740
Like other binary objects,
690
00:38:13,740 --> 00:38:18,680
Pluto and Charon orbit around a central gravitational point.
691
00:38:18,680 --> 00:38:21,280
Locked in this gravitational dance,
692
00:38:21,280 --> 00:38:26,220
Pluto and Charon always show each other the same face.
693
00:38:26,220 --> 00:38:28,820
One of the really interesting things about Pluto and Charon
694
00:38:28,820 --> 00:38:30,960
is that they're what we call tidally locked.
695
00:38:30,960 --> 00:38:32,420
When Pluto and Charon formed,
696
00:38:32,430 --> 00:38:34,830
they were probably both rotating on their own axes,
697
00:38:34,830 --> 00:38:37,430
but the two worlds actually slowed down their rotation
698
00:38:37,430 --> 00:38:39,030
and locked together,
699
00:38:39,030 --> 00:38:43,840
with one side constantly facing the other as they orbit around.
700
00:38:43,840 --> 00:38:46,840
But Pluto's rotation is tipped over
701
00:38:46,840 --> 00:38:49,180
like a top spinning on its side,
702
00:38:49,180 --> 00:38:55,310
so Charon's orbit around Pluto is also tipped over.
703
00:38:55,320 --> 00:38:57,920
Almost every planet in the solar system has an orbital axis
704
00:38:57,920 --> 00:39:00,120
that points in roughly the same direction.
705
00:39:00,120 --> 00:39:03,920
Pluto's is tilted down about 120 degrees.
706
00:39:03,930 --> 00:39:05,720
Scientists have long wondered
707
00:39:05,730 --> 00:39:07,990
what caused this disparity.
708
00:39:08,000 --> 00:39:10,200
Did Charon pull Pluto over?
709
00:39:10,200 --> 00:39:14,930
Or is the tilt a result of the impact that formed Charon?
710
00:39:14,940 --> 00:39:17,540
A clue was revealed when new horizons
711
00:39:17,540 --> 00:39:21,670
sent back images of Pluto's heart.
712
00:39:21,680 --> 00:39:23,740
One of the more endearing features of Pluto
713
00:39:23,750 --> 00:39:26,280
as the new horizon's probe approached it
714
00:39:26,280 --> 00:39:28,850
was a gigantic heart-shaped region
715
00:39:28,850 --> 00:39:32,950
on the side of Pluto facing the spacecraft.
716
00:39:32,950 --> 00:39:37,090
Sputnik Planitia, a bright, white heart
717
00:39:37,090 --> 00:39:40,960
against Pluto's dark, pockmarked surface.
718
00:39:40,960 --> 00:39:44,960
When we got closeups of this, it was completely fascinating.
719
00:39:47,440 --> 00:39:49,100
I gasped out loud.
720
00:39:49,100 --> 00:39:51,900
This is how shocking this was, and I remember saying,
721
00:39:51,910 --> 00:39:54,310
"oh, my gosh. There are no craters there!"
722
00:39:54,310 --> 00:39:57,510
It is smooth, like it's a frozen-over lake.
723
00:39:57,510 --> 00:39:59,510
This is indicative of something liquid,
724
00:39:59,510 --> 00:40:01,980
something flowing under the surface of Pluto,
725
00:40:01,980 --> 00:40:06,050
and what we're seeing is the top, frozen layer of it.
726
00:40:06,050 --> 00:40:07,990
There are even convection cells
727
00:40:07,990 --> 00:40:11,060
where the ice appears to be warming and spreading out.
728
00:40:11,060 --> 00:40:14,330
That suggests that underneath, there's a source of energy,
729
00:40:14,330 --> 00:40:18,200
and amazingly, there may even be a huge basin of liquid water
730
00:40:18,200 --> 00:40:20,130
under that ice.
731
00:40:20,130 --> 00:40:23,270
Sputnik Planitia may hide a giant,
732
00:40:23,270 --> 00:40:26,540
subterranean ocean of liquid water.
733
00:40:26,540 --> 00:40:31,340
It's also a gigantic scar on Pluto's surface.
734
00:40:31,350 --> 00:40:34,410
Most likely, given the shape and size,
735
00:40:34,420 --> 00:40:37,280
Sputnik Planitia was formed in a giant impact.
736
00:40:37,280 --> 00:40:40,020
Something smacked into Pluto.
737
00:40:40,020 --> 00:40:42,690
Could the combination of subsurface water
738
00:40:42,690 --> 00:40:46,760
and an impact account for Pluto's unusual tilt?
739
00:40:46,760 --> 00:40:49,160
One theory suggests that an object
740
00:40:49,160 --> 00:40:51,760
smashed into the top of Pluto.
741
00:40:51,770 --> 00:40:54,370
The impact shattered the surface,
742
00:40:54,370 --> 00:40:57,300
and water oozed up to fill the crater.
743
00:40:59,710 --> 00:41:02,770
The liquid water knocked Pluto off balance,
744
00:41:02,780 --> 00:41:05,580
and the gravitational dance with Charon
745
00:41:05,580 --> 00:41:10,380
spun this heavy heart out to the opposite side.
746
00:41:10,380 --> 00:41:13,390
One idea is that Sputnik Planitia formed where it is
747
00:41:13,390 --> 00:41:15,590
because ices can accumulate in the floor
748
00:41:15,590 --> 00:41:18,590
of a giant impact base.
749
00:41:18,590 --> 00:41:22,130
But it's not yet certain whether that's actually the case or not.
750
00:41:25,070 --> 00:41:28,800
Dwarf planets, once thought to be dead lumps,
751
00:41:28,800 --> 00:41:31,400
have come alive with mysteries.
752
00:41:31,410 --> 00:41:34,070
They've challenged all our assumptions,
753
00:41:34,070 --> 00:41:37,210
and yet, we've barely scratched the surface
754
00:41:37,210 --> 00:41:39,610
of these perplexing worlds.
755
00:41:39,610 --> 00:41:42,350
There are many more dwarf planets to discover,
756
00:41:42,350 --> 00:41:46,890
and who knows what surprises they may have in store?
757
00:41:46,890 --> 00:41:49,090
We don't know the final count of dwarf planets
758
00:41:49,090 --> 00:41:50,760
because we're still finding them,
759
00:41:50,760 --> 00:41:53,560
but I think that there are probably somewhere
760
00:41:53,560 --> 00:41:57,900
between 100 and 200 dwarf planets out past Pluto.
761
00:41:57,900 --> 00:42:00,170
There are probably many, many more as you go
762
00:42:00,170 --> 00:42:02,700
even further out in the solar system.
763
00:42:02,700 --> 00:42:05,840
Dwarf planets are, perhaps, the most interesting objects
764
00:42:05,840 --> 00:42:07,440
we've found in the solar system.
765
00:42:07,440 --> 00:42:10,040
They're diverse. They're geologically active.
766
00:42:10,040 --> 00:42:11,840
They contain liquid water.
767
00:42:11,850 --> 00:42:13,250
Just because they're small,
768
00:42:13,250 --> 00:42:14,980
that doesn't mean they're insignificant
769
00:42:14,980 --> 00:42:16,250
or they should be ignored.
770
00:42:16,250 --> 00:42:18,050
They are where it's at.
771
00:42:18,050 --> 00:42:20,990
For me, that is just the best, the most exciting.
772
00:42:20,990 --> 00:42:23,320
We have all of these new worlds to study
773
00:42:23,320 --> 00:42:27,390
that we didn't even dream existed just a few years ago.
774
00:42:27,400 --> 00:42:28,530
That's science.
61592
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