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from the drama of our planets origins
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and the birth of our solar system comes
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one of the most startling revelations of
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modern science
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the solar system we see today quiet
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stable was once a battlefield
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[Applause]
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newborn planets blasted through space
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competing for stable circularized orbits
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inside a grunge style mosh pit of gas
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and dust for those that find the right
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balance the prize is survival for the
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rest world shattering destruction a new
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look at the chaos of creation and a
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frightening possibility in our distant
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future
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[Music]
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Mars
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[Music]
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the Curiosity rover is searching for
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clues about the origins of the Red
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Planet it confirms the presence of
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oxygen and nitrogen isotopes hidden in
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the rocks and soil we use isotopes to
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try to figure out the history of planets
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partly because they are immune to many
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of the changes the chemical changes that
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occur when you have things like
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collisions and so forth isotopes the
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relative abundances of these isotopes
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are like fingerprints curiosity confirms
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a unique mix of isotope fingerprints the
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isotopes indicate that Mars formed
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elsewhere in the solar system and moved
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into our neighborhood our solar system
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is full of oddities pointing to an
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imperfect birth and a malformed
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evolution all of our planets go around
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the Sun in the same direction that the
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Sun is spinning this is the same
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direction that the clouds within our
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original nebula began to rotate six
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planets spin around their poles in the
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same direction for them the Sun rises in
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the east
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and sets in the west
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yet two planets spin the opposite
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direction for Venus and Uranus the Sun
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rises in the West and sets in the east
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Uranus not only has a retrograde spin it
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rolls on its side like a bowling ball at
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Neptune the icy moon Triton orbits
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backwards opposite from the direction of
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Neptune spin do these planets spin
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backwards because they were rocked by
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Titanic collisions in the past so we see
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evidence in the architecture of the
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solar system for not only collisions
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like Earth's moon and the fact that
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Venus is is rotating in the wrong
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direction and you're innocent sightings
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before all these things are attributed
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to collisions we also see in the
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asteroid belt and in the Kuiper belt the
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outer asteroid belt if you like we see
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that the orbits of these things look
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like they've been disturbed closer to
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home our own earth has an inexplicable
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23 and 1/2 degree tilt it's spin axis is
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radically misaligned from its magnetic
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pole and our moon is comparatively large
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for a planet our size
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now a new theory may be able to explain
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many of these oddities it is called the
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grand tack hypothesis
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four and a half to five billion years
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ago a gas giant planet arose inside a
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primordial disk of gas and dust
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Jupiter didn't just form where it is but
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formed then moved inward towards the Sun
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as it spirals toward the Sun Jupiter
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herds asteroids and rubble
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[Music]
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Jupiter's natural tendency is to drift
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in slowly through this debris field but
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that it's to traveling around
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the inner solar system is also thick
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with gas and dust the birth of our
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planetary system is well underway
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numerous worlds are born in this region
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including the earth primordial skies are
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ruled by chaos
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Jupiter's approach destabilizes these
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planets their orbits decay into wildly
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swinging ellipses
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some are tossed out others fall into the
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Sun their numbers are unknowable these
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are ghost worlds from a bygone age
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Jupiter just causes all heck to break
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out in the solar system and all that
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debris in the outer solar system gets
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flung inward towards the inner solar
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system and it was a busy time in the
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very early solar system and since we are
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colliding with each other all the time
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and then it stopped
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Jupiter's invasion of the inner solar
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system is mysteriously halted the planet
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makes a turn or n sailors parlance a
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grand tack lurking behind Jupiter is a
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second gas giant Saturn so as Jupiter
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was migrating inward Saturn was
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following it and growing and as Saturn
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was growing it came to have a size that
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it had a gravitational impact on Jupiter
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which became more important than the
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gravitational interaction between the
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gaseous disc and Jupiter
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they reverse direction and in a sense
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you can think of Saturn and Jupiter
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feeding off one another and moving back
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out gravity tugs each passing planet
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this transfers orbital energy from one
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world to another all you have to do is
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exert a very subtle little periodic
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force at the right time and you can have
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amazing changes in the motion of the
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object you're pushing on once enough
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energy has been transferred the planets
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synchronize their orbits they are said
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to be in a resonance for planets
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resonances are achieved and maintained
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through the mutual push and pull of
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gravity through the fabric of space
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there a key factor in the continuing
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evolution of our solar system this
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effect can be duplicated in the lab we
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have ten metronomes here set up on a
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swinging platform they have little
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weights on pendulums here but they've
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all been set at the same frequency and
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I'm going to try to start them as best I
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can completely out of phase randomly so
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their oscillation is going to transfer
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energy by the swinging of this plastic
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sheet to the other metronomes that are
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out of phase to get into phase with the
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majority it's inevitable that there's
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going to be some majority group which
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starts out swinging more or less
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together and they are eventually going
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to win out
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aha
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maybe in this corner I see four that are
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pretty closely synced yes now it's more
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like five six they have one that's
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almost completely out of phase every
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time the majority hits a beat it's going
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to give a little impulse a little push
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to the platform and that push is
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transferred to the metronome that's not
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in sync because the platform you can
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actually see this platform vibrating
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back and forth in sync with the majority
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of these metronomes working on this one
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pretty close to resonance right now as
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the metronomes achieve resonance it's
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important to notice how the platform
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shakes now it doesn't have to just be
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the force that's being transmitted by
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the plastic platform it could be a force
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at a great distance for example the
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force of gravity just these small little
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seemingly insignificant pushes building
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up over multiple cycles can have
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dramatic energy transfer that is how
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planets do it like the metronomes the
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two gas giants form a resonance
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we don't know exactly how long that took
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but we have some fiducial marks for
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timing in the solar system formation and
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that means that the grand tack had to
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have occurred relatively quickly
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talking hundreds of thousands of years
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perhaps two million years the two
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planets retreat until they've reached
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their current positions the sequence of
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planets as we find them today is based
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on Jupiter and Saturn's orbits
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the planets eventually achieve a
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sequencing that many students learn
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through a mnemonic such as my very
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educated mother just served us nine
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pizzas was there a time when the
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mnemonic was scrambled seems very likely
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the answers yes not to mention a lot of
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additional letters were probably in
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there as well
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Jupiter's Menace of the inner solar
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system is finally over
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if Saturn had not formed at the right
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time in the sufficient size Jupiter
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would have continued migrating in
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throwing out objects unfortunate objects
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in the inner solar system and ending up
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very close to the Sun where it would
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stay yes the earth would be gone or the
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earth would have had it a terrifying
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encounter with Jupiter and would have
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been it had its orbit changed
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dramatically too gosh knows what
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there is mounting evidence that earth
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had a terrifying visitor not Jupiter but
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another world fail
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FEA was essentially another proto-earth
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where there were a number of these
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objects flying around and day it took
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time to grow just like the earth did
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they probably had rather similar
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histories and for one reason or another
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the orbit of theta was perturbed such
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that it collided with the earth
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saya was this planet everybody that was
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roughly the size of Mars and through
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this collision a lot of particles were
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ejected probably completely destroyed we
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don't really know how much of saya was
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preserved earth is rocked off its axis
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its surface liquefied
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chunks of Earth's mantle are shoved into
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space
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as a planetary body FEA ceases to exist
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its remains are absorbed by the earth
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and intermingled with the debris field a
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new planetary body is formed the moon
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further evidence is found in rock
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samples from the Apollo moon landings
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Lisi is a sample from the moon if you
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can sit this was collected by the Apollo
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15 mission moon rocks contain isotopes
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identical to those found on earth when
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the moon arose it is first covered with
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a magma ocean people imagine the you
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know magma ocean to be like this
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magnetic chamber I am describing but at
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the surface and covering a whole planet
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I see it as this ocean like the Pacific
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but this has to be like completely
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magnetic orange and like probably like
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flexing around and probably moving
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conditions in the lunar magma are as
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hellish as we can imagine
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but a microscopic treasure forms in the
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magma crystal zircons these are the same
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gemstones used in jewelry but the
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zircons and the apollo moonrocks
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yield a different treasure so the zircon
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are very important because we know they
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crystallize in this union magma ocean we
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know roughly when they crystallize in
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the renal that motion so they are one of
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these old piece of the Moon that we are
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looking for one of these old piece that
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we can use to to date the origin of the
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Moon zircons not only give the age of
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the Moon they set a specific date for
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the collision
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the edge of the moon is 4.51 billion
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years old
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4.5 1 billion years ago fááá becomes
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part of earth and forms the moon but the
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story is not over space probes measure
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the moon
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slipping 3.8 centimeters further away
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each year one day the moon will break
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free when that day comes there will be
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no more tides no more romantic moonlit
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nights could planetary orbits be
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inherently unstable could the chaos of
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planetary migration return oh Tremont's
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Observatory France it's here that a
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discovery from a faraway star gives one
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of the biggest revelations about our own
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solar system the story begins when Swiss
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astronomers DDA quello and michelle Maor
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noticed something unusual about a star
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50 light-years away in the constellation
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of Pegasus everything about this star is
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ordinary a main-sequence midlife yellow
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dwarf just like our Sun but with one
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strange difference the star at Pegasus
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51 is rocking back and forth
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it's a weird anomaly astronomers have
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never seen before they check their
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instruments everything is working
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including their new spectrograph a
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00:17:49,519 --> 00:17:56,089
device that splits the starlight from
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Pegasus into rainbow colors hidden
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inside the colors are patterns of lines
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by tracking the day-to-day movement of
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these lines astronomers make a startling
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discovery
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Pegasus 51 has a planet but no one has
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ever seen a world like this it's half
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the mass of Jupiter yet it's extremely
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close to its star nine times closer than
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mercury is to the Sun the planet at 51
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Pegasus must be inside the corona
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broiling and temperatures over a million
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degrees Fahrenheit soon another planet
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is found around another star and then
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another and another
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astronomers have now confirmed over 3700
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exoplanets beyond our solar system
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nearly all of them are Jupiter class
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planets grazing their host star there a
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new previously unknown type called hot
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Jupiters
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they're so numerous hot Jupiters
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challenged theories about the origins of
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planetary systems it's very difficult to
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make a planet close to the star because
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there isn't enough mass to build a giant
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planet very close to the star and
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there's gravitational frustrations for
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trying to build a planet very close to
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start astronomy is shaken with a new
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revelation
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planets do not stay put where they're
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born when they're big enough they
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migrate it's a process called planetary
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migration and yet our own solar system
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00:19:43,538 --> 00:19:56,679
has no hot Jupiter astronomers realize
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00:19:53,409 --> 00:19:59,500
the Jupiter in our solar system was once
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on the move as well but its migration
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was halted by a resonance with Saturn
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Pegasus 51 shows where a planet lands
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when its migration is not blocked the
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strongest evidence for the grand tak
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hypothesis comes not from our solar
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system but from exo world's charted
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around other stars planetary migration
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is a universal concept we see it
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evidence of it out there in extrasolar
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planets other solar systems there's no
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00:20:31,659 --> 00:20:35,720
reason why planet migration shouldn't
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have operated in our own solar system
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[Music]
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the New Horizons probe finds evidence
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00:20:47,440 --> 00:20:51,929
for roving planets within our solar
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system
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while charting ancient craters on Pluto
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and on the surfaces of its moons
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the science team discovered many craters
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are the same age this suggests that they
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were formed by a single event even way
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out here tiny Pluto was smashed by a
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wandering planet the Pluto catastrophe
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may be related to other planetary
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migrations in the outer solar system
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[Music]
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it was noticed that the exact orbits of
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the giant planets particularly the outer
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giant planets the icy planets Uranus and
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Neptune can be explained by their
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migration outward there's a point in
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time about 3.8 billion years ago or a
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year nasa neptune trait and it's because
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of what some of these mean motion
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resonance interactions that we were
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talking about earlier so this mean
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motion resonance involving Jupiter and
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Saturn and so forth just causes all heck
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to break out in the solar system you're
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innocent Neptune all of a sudden in 3.8
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million years they they literally swap
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places and all that debris in the outer
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solar system gets flung inward towards
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the inner solar system the disruption in
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the outer solar system causes a new wave
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of violence astronomers call this epoch
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the late heavy bombardment
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much of the cratering we see on our moon
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today is from this period
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it may be possible that swapping orbits
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with Uranus is how Neptune got its moon
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today the epic of planetary migration
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appears to be over the solar system
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seems stable but what does the future
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hold computer simulations reveal what
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may be the greatest threat to the solar
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system in over 4 billion years it comes
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from a very special relationship between
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Jupiter and Mercury Mercury's orbit is
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slowly perturbed thanks to a subtle but
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constant gravitational nudge from
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Jupiter a new resonance like the one
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between Saturn and Jupiter that saved
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the inner solar system is forming
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between Jupiter and Mercury in 2001
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computer models for the solar system
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were run 2,500 times they plug in the
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positions and the orbits of all the
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planets in the solar system in a
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computer and they just rillette it run
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through time through millions of years
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hundreds of millions of years billions
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of years to find out whether or not
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these orbits are stable change the
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location of one planet say mercury by
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one millimeter and you find that that
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00:24:09,410 --> 00:24:15,800
change will give completely different
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predictions about where everything is
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going to be millions of years in the
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future
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[Music]
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to see how quickly and easily things can
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change we have only to go back to our
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metronomes all I have to do is stop this
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platform from moving so that cannot
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swing freely now there's no way for the
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metronomes to influence each other
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they're good metronomes but they're not
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perfect they can't be going at exactly
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the same frequency in the same phase and
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they're just going to fall apart because
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they have no way of forcing the others
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to go to resonance
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the same applies to planets any small
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change can disrupt their harmony or
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restore it now that the platform is free
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to swing again it can again transfer
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energy and sync them up just like we saw
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it the first time scientists want to
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understand the consequences of a
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destabilized planet mercury in one case
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mercury leaves the solar system the loss
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of its gravitational pull disrupts the
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balance of both Venus and the earth
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Earth and Venus swap orbits
441
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the superheated atmosphere of Venus cool
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massive rains pour onto the face of the
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desert planet oceans arise the land
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00:25:52,980 --> 00:26:00,819
cools and the air thins even the remains
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of an ancient visitor begin to cool off
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[Music]
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Venus becomes like Earth but the reverse
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happens to the earth as Earth settles
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into Venus's orbit temperatures rise the
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00:26:19,559 --> 00:26:29,159
air becomes unbreathable glaciers melt
451
00:26:24,410 --> 00:26:32,250
oceans boil the Sun looms larger in the
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00:26:29,160 --> 00:26:37,470
sky only to be obscured by a thickening
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00:26:32,250 --> 00:26:42,269
cloud cover suffering will be great but
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brief the entire four billion year
455
00:26:42,269 --> 00:26:48,289
pageant of life is cooked in a matter of
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days
457
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complete and utter destruction and
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elimination of all life on earth not
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judging in that higher life much talking
460
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about civilization but everything a
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sterilization of the planet is something
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that I would want to think about a bit
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sterilized uninhabitable and quiet there
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is another possibility
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equally dark and apocalyptic
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a runaway mercury is deflected by the
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gravity of Venus and barrels toward the
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earth it may be a frightening encore to
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the opening act of our solar system
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the equilibrium of the ages is over
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if this scenario is correct mercury
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crashes into the earth just as fááá did
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four billion years ago the question is
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could it happen today
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or is it a fate far away in the future
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at a time when mankind itself is but a
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distant memory
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the problem is that even with a perfect
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computer that understands all of the
480
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laws of motion perfectly not just
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gravity but all the other subtle forces
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that go into it you cannot give it
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accurate enough initial information
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about the locations the masses the sizes
485
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the speeds of all of the objects in the
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solar system
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odds are we may never see such a
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calamity and yet among the billions of
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stars in our galaxy how many worlds are
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on the move
how many will share this faint
36573
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