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Male narrator: In the beginning,
there was darkness,
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and then, bang,
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giving birth to an endless
expanding existence
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of time, space, and matter.
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Every day, new discoveries
are unlocking the mysterious,
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the mind-blowing,
the deadly secrets
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of a place we call
The Universe.
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The numbers of the universe
boggle the human mind.
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- In the observable part
of the universe,
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there is something like
100 billion galaxies,
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each with billions of stars.
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- The Andromeda Galaxy is about
2.5 million light-years away.
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- The Earth is orbiting the Sun
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at a speed
of about 66,000 miles per hour.
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Narrator: Most of us give up
even trying to comprehend
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such titanic sizes, distances,
and speeds.
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But are there ways
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to bring the sweep of the cosmos
down to Earth
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TO help us understand how big,
how far, and how fast?
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Planet Earth,
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for all its wide expanses,
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deep seas,
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and massive mountains,
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amounts to a speck of dust
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when stacked up against
the immensity of the cosmos.
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- The observable universe
contains of order
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100 billion galaxies.
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And then each galaxy,
like the Milky Way,
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contains of order
100 billion stars.
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- The numbers quickly get up
into the millions
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and then the billions
and even the trillions.
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And by then, we've really lost
all sense
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of what that really means.
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Narrator: The human mind
is finely tuned
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to deal with the scale
of day-to-day experience.
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The brain can understand
traveling 50 miles in a day.
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But what about 500,0007?
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And a person may know
what it's like
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to move at 100 miles per hour.
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But what about 100 million?
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- Numbers like millions
and billions
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and certainly trillions
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are very hard for most people
to imagine,
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because, frankly, most of us
don't have billions
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or trillions of anything.
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Narrator: So how can we
ever know the universe
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if our brains can't really
comprehend its massive scale?
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- Doing scale models
of objects in the universe
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is really helpful,
because it brings them down
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to sizes that we can imagine,
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that we do see in our normal,
everyday lives.
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Narrator:
We can start by cutting
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the biggest players
of the night sky—
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Planets, stars, and galaxies—
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Down to an earthly scale.
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There are two ways
to evaluate size.
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We can measure dimensions—
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Meaning height,
length, and width—
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Or calculate bulk,
also known as mass.
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Bigger doesn't always mean
more massive.
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- Let's say a balloon has
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the same volume
as a bowling ball.
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But the bowling ball has
more mass
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because it's denser.
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It's just got more mass crammed
into that same volume.
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Narrator: To help get a grasp
on some of the immense masses
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floating around our universe,
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astronomer Laura Danly visits
a monster truck rally...
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a place where objects of hugely
differing masses often collide.
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- We've got everything
from a small toy truck
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to the giant monster truck...
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and that gives us
a range of mass
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that will help us understand
how massive things are
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in our solar system
compared to each other
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and how massive our own Sun is
compared to some other stars.
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Narrator: We begin
the comparison with Jupiter,
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known as the king of planets,
and for good reason.
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Its mass amounts to more than
4 octillion pounds.
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That's a 4
followed by 27 zeros.
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Put another way, it would take
more than 300 Earths
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to match Jupiter's mass.
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But even that is measly
when compared to the Sun.
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- The Sun is by far
the most massive thing
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in our solar system.
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It's about 1,000 times
more massive than Jupiter,
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the biggest planet.
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Well, by comparison, this car
behind me is about 3,000 pounds,
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and this little toy truck is
about 3 pounds.
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So that's
about the same difference
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between the Sun and Jupiter.
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Narrator:
It's a crushing difference,
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as 3,000 pounds
make perfectly clear.
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But remember, this is
a monster truck rally,
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and the junk car
representing our Sun
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may regret picking on
little Jupiter.
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- The Sun is the most massive
object in our solar system,
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but it's not the most massive
star in the galaxy.
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There are a lot of stars
more massive than the Sun.
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Narrator: To envision
the disparity between the Sun
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and a more massive star...
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let's keep the 3,000-pound
junk car as the Sun
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and put it up against
a 10,000-pound monster truck
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representing a star
some 75 light-years away.
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- The difference between
the monster truck and the car
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is about the same difference
as a star called Regulus—
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The bright star
right in the middle of Leo,
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about 3 1/2 times as massive
as our Sun.
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Narrator: Three times more
massive may not seem like much,
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but don't forget we're now
pitting galactic giants
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against each other.
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[engine revs]
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- Well, that was quite a shock.
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But as you can see, three times
the mass difference
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makes a difference.
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If we could somehow bring
Regulus here
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and have it sit on top
of the Sun,
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that's about
the same comparison.
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Narrator: But even
monster truck-sized Regulus
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can't stack up
to the immense mass
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of the true titans
of the universe.
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- The most massive star we know
orbits around the Milky Way—
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A little companion galaxy called
the Large Magellanic Cloud—
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In the middle of a nebula called
the Tarantula Nebula.
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That star has a kind of
boring name—R136a—
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But it's still
a very massive star.
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Narrator. R136a is a young star
about a million years old.
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Its surface temperature is
70,000 degrees,
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about 7 times hotter
than our Sun.
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Before 2010,
stars were thought to form
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no bigger than 150 times
the mass of the Sun.
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But new discoveries
have doubled that limit.
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- We think R136a
is probably about 250,
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maybe as much as 300 times
the mass of our Sun.
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Narrator: To represent
this massive star,
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you need
a truly monstrous truck.
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This monster
is 100 times heavier.
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But extreme mass also comes
in small packages,
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where density takes
the force of gravity
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into radical territory.
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The greatest massive
bang for the buck
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we can see in the universe
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comes from a stellar object
known as a neutron star.
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A neutron star is the leftover
core of a supernova explosion,
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with its mass packed
astoundingly tight.
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- It's got 1 1/2 times
all of the mass of our Sun
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crammed into a volume
of about 10 miles across.
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If you crammed one monster truck
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down into the size
of a sugar cube,
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that would not be anywhere close
to as dense as a neutron star.
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I'd need
10 million monster trucks
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crashed down into the size
of a sugar cube.
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Narrator: Stack these 10 million
monster-truck sugar cubes
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ten miles high and wide,
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and you've got yourself
a neutron star.
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- Neutron stars are just
bizarrely extreme objects.
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If you were to try to land
on a neutron star,
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it would be
absolutely impossible,
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because you would find that
on the neutron star,
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you weigh about 5 billion times
more than you do here on Earth.
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Narrator:
But mass isn't everything
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when it comes to finding out
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just how big
the biggest stars can be.
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The universe is also filled
with titans
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that take up
unimaginable amounts of space.
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Some of the tiny pinpricks
of light we see from Earth
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are actually stars big enough to
swallow our entire solar system.
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Can the human mind
even comprehend
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the largest star in the galaxy?
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We're bringing the sizes,
speeds, and distances
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of our vast universe
down to a scale
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the human mind can comprehend.
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The biggest thing
in our solar system by far
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is the Sun.
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In terms of sheer mass,
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it weighs over 300,000 times
more than the Earth.
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But in terms of volume,
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it's also the solar system's
physically largest object,
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at 870,000 miles across.
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- So the Sun is really big
compared to the Earth.
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It's 109 times as wide
as the Earth.
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That actually means
that over a million Earths
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could fit inside the volume
of the Sun.
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It's really big.
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Narrator: But as enormous as
the Sun is in earthly terms,
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our home star seems puny
when stacked against
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our galaxy's lineup
of stellar mammoths.
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With strange names taken
from history and science,
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they push the envelope
of what it means to be a star.
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Consider them in turn:
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Vega...
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Bellatrix...
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Epsilon Can is Major is...
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Dubhe...
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Aldebaran...
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and finally,
the super-enormous Betelguese...
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and VY Can is Major is.
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- Oh, wow.
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Narrator:
Astronomer Alex Filippenko
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attempts to bring them
down to Earth
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in an airplane hangar.
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- We're here
in this airport hangar today
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in order to try to illustrate
the relative sizes of stars,
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in particular big stars.
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We're going to inflate
some balloons,
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and even some really big
weather balloons,
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and show them in comparison
with the Sun,
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which we've scaled down
to the size of a bowling ball.
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[air hissing]
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Narrator: The bowling-ball Sun
is 8 1/2 inches across,
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which would make the Earth
no bigger than a tiny bead.
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- My two assistants are
balloon experts.
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They know how to inflate
balloons with helium
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and tie them off,
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and they know how much
to inflate them.
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00:12:27,537 --> 00:12:29,747
So they're going to inflate
these different balloons
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to different sizes.
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Narrator:
Inflating the balloons
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will take us
on a scaled-down tour
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of the Sun's big, bigger,
and biggest brothers.
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First stop: the star Vega.
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Located
in the constellation Lyra,
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Vega is one
of the five brightest stars
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in the night sky.
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It glows blue-white because
it burns hotter than our Sun.
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00:13:02,072 --> 00:13:05,366
- Okay, so I've got
my bowling-ball Sun here.
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Guys, how big is this balloon?
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00:13:06,952 --> 00:13:09,663
- Let's check it out.
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00:13:09,663 --> 00:13:11,414
It's about 2 feet.
- Right about 2 feet.
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- 2 feet, so that's—that's
about 2 1/2 times the size
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of the bowling ball.
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So that's like the star Vega.
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It's a bluish white star,
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25 light-years away,
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very bright star in the sky.
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Narrator: Next up is Bellatrix,
a star in Orion the Hunter...
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the brightest constellation
in the sky.
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Well-known stars pinpoint
its torso and belt.
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00:13:36,732 --> 00:13:40,944
Another blue giant, Bellatrix is
at Orion's right shoulder
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and shines 240 light-years away.
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- So here's a bigger balloon.
What's its size?
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00:13:47,743 --> 00:13:50,328
- This is 4 feet.
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00:13:50,329 --> 00:13:52,831
- 4 feet, so that's about
5 1/2 times the size
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00:13:52,831 --> 00:13:55,291
of my bowling ball—
my Sun.
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00:13:55,292 --> 00:13:59,754
So this is a bigger star.
It's kind of like Bellatrix.
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Narrator: Bigger than Bellatrix
is the hot blue star Adhara,
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00:14:04,926 --> 00:14:09,055
also known as
Epsilon Can is Major is.
247
00:14:09,056 --> 00:14:12,851
Can is Major is a constellation
whose name translates
248
00:14:12,851 --> 00:14:16,104
as "the great dog."
249
00:14:16,104 --> 00:14:18,981
- Wow, now here's a big star,
huh?
250
00:14:18,982 --> 00:14:21,317
- This one is 12 feet.
251
00:14:21,318 --> 00:14:25,155
- This thing is 17 times wider
than the Sun.
252
00:14:25,155 --> 00:14:27,782
That's kind of like the star
Epsilon Can is Major is
253
00:14:27,783 --> 00:14:29,659
in the constellation
Can is Major.
254
00:14:29,659 --> 00:14:32,286
That's the same constellation
that Sirius is in.
255
00:14:32,287 --> 00:14:33,997
Sirius is the brightest star
in the sky,
256
00:14:33,997 --> 00:14:37,917
but Epsilon Can is Major is is
430 light-years away.
257
00:14:37,918 --> 00:14:40,378
If it were at the same distance
as Sirius,
258
00:14:40,379 --> 00:14:44,508
it would appear
15 times brighter.
259
00:14:44,508 --> 00:14:49,008
Narrator: Almost twice as big as
Epsilon Can is Major is is Dubhe,
260
00:14:49,012 --> 00:14:52,765
a giant star on the lip
of the Big Dipper,
261
00:14:52,766 --> 00:14:56,186
120 light-years away.
262
00:14:56,186 --> 00:14:57,812
- Wow, cool.
263
00:14:57,813 --> 00:14:59,856
Well, here I see
an even bigger balloon.
264
00:14:59,856 --> 00:15:01,607
What's its diameter?
265
00:15:01,608 --> 00:15:02,775
- Let's see.
266
00:15:02,776 --> 00:15:05,028
21 feet.
- 21 feet.
267
00:15:05,028 --> 00:15:08,489
So that's about 30
of my bowling-ball Suns.
268
00:15:08,490 --> 00:15:11,034
In fact, that's about the size
of the star Dubhe.
269
00:15:11,034 --> 00:15:14,328
That star Dubhe is different
from the others that we've seen.
270
00:15:14,329 --> 00:15:16,039
It's what's called a red giant.
271
00:15:16,039 --> 00:15:17,707
It's got kind of
an orange color.
272
00:15:17,707 --> 00:15:21,377
It's cooler than the blue-white
ones that we've seen previously.
273
00:15:21,378 --> 00:15:25,878
Narrator. Amazingly, stars come
in larger sizes still.
274
00:15:26,133 --> 00:15:28,343
And even an airplane hangar
275
00:15:28,343 --> 00:15:31,095
isn't big enough
to contain them.
276
00:15:31,096 --> 00:15:33,640
Here's where we have to place
Aldebaran,
277
00:15:33,640 --> 00:15:37,560
a monster star known
since ancient times
278
00:15:37,561 --> 00:15:42,061
and once thought to be a sign
of riches and honor.
279
00:15:42,357 --> 00:15:44,525
- This balloon is
about 32 feet across.
280
00:15:44,526 --> 00:15:47,862
Now, that's roughly 45 times
bigger than this bowling ball
281
00:15:47,863 --> 00:15:49,656
which represents our Sun.
282
00:15:49,656 --> 00:15:53,534
Now, this balloon then is about
the size of the star Aldebaran,
283
00:15:53,535 --> 00:15:56,287
a red giant in Taurus the Bull.
284
00:15:56,288 --> 00:15:58,748
It's about 65 light-years away,
285
00:15:58,748 --> 00:16:03,127
and its true color is
roughly orange.
286
00:16:03,128 --> 00:16:05,880
Narrator. Now even the biggest
balloons fall short
287
00:16:05,881 --> 00:16:10,381
in representing the size
of the galaxy's biggest stars.
288
00:16:11,094 --> 00:16:15,348
Betelgeuse, for instance,
is another star in Orion.
289
00:16:15,348 --> 00:16:17,933
650 light-years away,
290
00:16:17,934 --> 00:16:22,434
it is a thousand times
the size of the Sun.
291
00:16:22,731 --> 00:16:27,231
- Betelgeuse is so large
that its radius would extend
292
00:16:27,235 --> 00:16:29,487
roughly to the orbit of Jupiter.
293
00:16:29,488 --> 00:16:33,700
So if Betelgeuse was actually
in the solar system,
294
00:16:33,700 --> 00:16:34,867
then all of the eight planets
295
00:16:34,868 --> 00:16:36,786
would be completely
either destroyed
296
00:16:36,786 --> 00:16:40,164
or totally too hot
to be habitable.
297
00:16:40,165 --> 00:16:41,791
Narrator:
But the largest known star
298
00:16:41,791 --> 00:16:46,291
is a beast by the name
of VY Can is Major is.
299
00:16:47,214 --> 00:16:49,132
By some estimates,
it extends
300
00:16:49,132 --> 00:16:53,632
to 2,000 times the diameter
of our Sun.
301
00:16:55,555 --> 00:16:58,140
- That is a truly
gargantuan star.
302
00:16:58,141 --> 00:17:00,143
If there were
a commercial airplane
303
00:17:00,143 --> 00:17:03,146
flying just outside
VY Can is Major is,
304
00:17:03,146 --> 00:17:07,646
it would take it about
1,200 years to fully circle it.
305
00:17:07,984 --> 00:17:10,945
Narrator. Any object
on this enormous scale
306
00:17:10,946 --> 00:17:14,783
seems truly alien
to the human mind...
307
00:17:14,783 --> 00:17:17,786
an intimidating answer
to the "how big" question
308
00:17:17,786 --> 00:17:20,163
about the universe.
309
00:17:20,163 --> 00:17:24,000
No less discomforting is
"how far?"
310
00:17:24,000 --> 00:17:28,500
Because distances between
planets, stars, and galaxies
311
00:17:28,588 --> 00:17:33,088
stretch beyond
all human experience.
312
00:17:34,010 --> 00:17:36,512
- So a really great way
of bringing it home
313
00:17:36,513 --> 00:17:41,013
is to scale everything down
to a more human scale.
314
00:17:41,351 --> 00:17:44,479
We're better at understanding
the relative sizes of things
315
00:17:44,479 --> 00:17:47,523
than abstract absolute numbers.
316
00:17:47,524 --> 00:17:50,693
Narrator: Take the Moon.
317
00:17:50,694 --> 00:17:55,194
It lies a little less than
250,000 miles from Earth.
318
00:17:56,032 --> 00:17:59,493
You might think this isn't
all that far.
319
00:17:59,494 --> 00:18:01,787
Well, think again.
320
00:18:01,788 --> 00:18:03,498
- Imagine if I shrank the Earth
321
00:18:03,498 --> 00:18:05,833
down to about the size
of a basketball.
322
00:18:05,834 --> 00:18:09,629
So if the Earth was about
the size of this object here,
323
00:18:09,629 --> 00:18:11,797
I would actually have
the Moon be
324
00:18:11,798 --> 00:18:13,883
about the size
of this tennis ball.
325
00:18:13,883 --> 00:18:15,926
So the next question
you might ask is,
326
00:18:15,927 --> 00:18:18,846
"Given the relative sizes
of these things,
327
00:18:18,847 --> 00:18:21,558
how far apart are they
going to be from each other?"
328
00:18:21,558 --> 00:18:23,893
To show you, I'm actually going
to need some help.
329
00:18:23,893 --> 00:18:26,729
So Johnny is actually going
to hold the Earth for me
330
00:18:26,730 --> 00:18:29,524
while I actually take the Moon
and measure out
331
00:18:29,524 --> 00:18:31,275
how far away it needs to be.
332
00:18:31,276 --> 00:18:34,404
So here goes.
333
00:18:34,404 --> 00:18:37,532
1 foot, 2 feet...
334
00:18:37,532 --> 00:18:42,032
all the way back,
we're already at 10 feet.
335
00:18:42,162 --> 00:18:44,581
Probably go even more.
336
00:18:44,581 --> 00:18:45,707
It's already past 15.
337
00:18:45,707 --> 00:18:48,167
We've got to go much further.
338
00:18:48,168 --> 00:18:51,546
And here we are at 21 feet.
339
00:18:51,546 --> 00:18:55,424
That's actually how far away
the Moon is from the Earth
340
00:18:55,425 --> 00:18:57,718
in our scale model.
341
00:18:57,719 --> 00:19:00,638
Narrator: At 239,000 miles,
342
00:19:00,639 --> 00:19:04,726
the Earth-Moon distance
has now become familiar to us,
343
00:19:04,726 --> 00:19:08,730
because of Apollo missions
to the Moon.
344
00:19:08,730 --> 00:19:11,357
This is one of the few
astronomical spans
345
00:19:11,358 --> 00:19:14,402
we can readily understand.
346
00:19:14,402 --> 00:19:16,987
In six manned moon landings,
347
00:19:16,988 --> 00:19:18,447
we learned that the travel time
348
00:19:18,448 --> 00:19:21,284
was a little more
than three days.
349
00:19:21,284 --> 00:19:23,744
And the lunar commute
has become a part
350
00:19:23,745 --> 00:19:25,872
of our collective knowledge.
351
00:19:25,872 --> 00:19:27,290
- Engine stop.
352
00:19:27,290 --> 00:19:30,918
Okay, Houston,
the Challenger has landed.
353
00:19:30,919 --> 00:19:32,295
Narrator:
But beyond the Moon,
354
00:19:32,295 --> 00:19:36,048
the solar system extends
to distances so vast,
355
00:19:36,049 --> 00:19:40,053
again, our limited minds
aren't really up to the task.
356
00:19:40,053 --> 00:19:42,805
But what would happen
if we literally brought
357
00:19:42,806 --> 00:19:46,392
all the planets down to Earth?
358
00:19:53,066 --> 00:19:57,566
Narrator: It can be overwhelming
to consider how big, how far,
359
00:19:57,987 --> 00:20:02,157
and how fast everything is
in our universe.
360
00:20:02,158 --> 00:20:04,535
Even in our solar system,
361
00:20:04,536 --> 00:20:08,790
the distances are almost
unimaginably vast.
362
00:20:08,790 --> 00:20:11,250
That's why we're shrinking
our solar system
363
00:20:11,251 --> 00:20:15,672
and bringing it down to Earth.
364
00:20:15,672 --> 00:20:20,172
- Imagine if we took
the 870,000 miles
365
00:20:21,845 --> 00:20:23,513
of diameter of the Sun
366
00:20:23,513 --> 00:20:26,849
and shrank it down
to the size of a bowling ball.
367
00:20:26,850 --> 00:20:28,518
What would that do
to the planets?
368
00:20:28,518 --> 00:20:33,018
Well, we'd have to shrink them
down to sizes that we have here.
369
00:20:34,691 --> 00:20:37,527
So we have the eight planets
of the solar system lined out,
370
00:20:37,527 --> 00:20:41,906
starting with Mercury
all the way out to Neptune.
371
00:20:41,906 --> 00:20:45,618
So in this scale model,
our Earth, our home,
372
00:20:45,618 --> 00:20:48,203
is this tiny little bead,
373
00:20:48,204 --> 00:20:51,874
while the Sun is
this bowling ball.
374
00:20:51,875 --> 00:20:54,002
Narrator: These bead
and marble planets
375
00:20:54,002 --> 00:20:56,713
may be to scale
with the bowling ball Sun,
376
00:20:56,713 --> 00:21:01,213
but the distances
between them aren't.
377
00:21:01,217 --> 00:21:04,762
To demonstrate that,
physicist Clifford Johnson
378
00:21:04,763 --> 00:21:08,057
is going to walk the length
of this miniature solar system
379
00:21:08,057 --> 00:21:11,852
laid out along a runway.
380
00:21:11,853 --> 00:21:14,438
- I have Johnny here,
who's going to help me measure
381
00:21:14,439 --> 00:21:17,066
the distances
with this surveyor's wheel.
382
00:21:17,066 --> 00:21:18,942
Okay, so let's go and explore
the solar system.
383
00:21:18,943 --> 00:21:21,195
- All right, let's do it.
384
00:21:21,196 --> 00:21:24,866
Narrator. Each foot
in this scaled-down solar system
385
00:21:24,866 --> 00:21:26,742
represents 1 million miles
386
00:21:26,743 --> 00:21:29,245
in the distances
between the planets.
387
00:21:29,245 --> 00:21:32,748
[wheel clacking rhythmically]
388
00:21:32,749 --> 00:21:34,375
- And here we are at Mercury.
389
00:21:34,375 --> 00:21:36,335
- And that's 36 feet.
390
00:21:36,336 --> 00:21:39,505
- In reality, it's actually
about 36 million miles
391
00:21:39,506 --> 00:21:44,006
away from the Sun.
392
00:21:44,010 --> 00:21:46,554
It's amazing just how far
393
00:21:46,554 --> 00:21:48,931
the very first planet
of the solar system is
394
00:21:48,932 --> 00:21:50,767
from the Sun.
395
00:21:50,767 --> 00:21:52,685
So now let's go on
to the second planet.
396
00:21:52,685 --> 00:21:55,104
- Here we go.
397
00:22:00,527 --> 00:22:02,445
- So here we are at Venus.
398
00:22:02,445 --> 00:22:04,530
- And that's 67 feet.
399
00:22:04,531 --> 00:22:06,574
- So this bead
representing Venus
400
00:22:06,574 --> 00:22:11,074
is about twice as far
from the Sun as Mercury is.
401
00:22:11,788 --> 00:22:16,288
It's actually, in reality,
about 67 million miles away.
402
00:22:17,544 --> 00:22:19,629
[clacking of wheeled gauge]
403
00:22:19,629 --> 00:22:21,672
And here we are at the Earth.
404
00:22:21,673 --> 00:22:24,133
- And that's 93 feet.
405
00:22:24,133 --> 00:22:27,719
- We have the Earth here
represented by this marble.
406
00:22:27,720 --> 00:22:31,432
And, in fact,
it's, in reality,
407
00:22:31,432 --> 00:22:34,268
93 million miles away
from the Sun.
408
00:22:34,269 --> 00:22:38,769
The way the bowling ball looks
in terms of the size from here
409
00:22:39,148 --> 00:22:42,651
is about the size
the Sun appears in our sky.
410
00:22:42,652 --> 00:22:46,072
We have this blue bead
representing the Earth.
411
00:22:46,072 --> 00:22:47,907
And about 2 1/2 inches away,
412
00:22:47,907 --> 00:22:51,493
we have a much smaller bead
representing the Moon.
413
00:22:51,494 --> 00:22:53,829
Narrator. Remember
that on a different scale,
414
00:22:53,830 --> 00:22:56,374
with Earth the size
of a basketball,
415
00:22:56,374 --> 00:22:59,335
the Moon was 21 feet away.
416
00:22:59,335 --> 00:23:02,171
To bring the whole solar system
into the picture,
417
00:23:02,171 --> 00:23:05,048
we've had to scale down
the Earth-Moon distance
418
00:23:05,049 --> 00:23:07,342
to mere inches.
419
00:23:07,343 --> 00:23:09,803
- This tiny distance
between the Earth and Moon
420
00:23:09,804 --> 00:23:14,304
is the limit so far
of manned exploration of space.
421
00:23:16,561 --> 00:23:20,106
Hopefully, we'll do a lot better
in the years to come.
422
00:23:20,106 --> 00:23:21,816
Narrator:
On our runway,
423
00:23:21,816 --> 00:23:25,152
Mars orbits
another 49 feet away,
424
00:23:25,153 --> 00:23:29,653
or almost 142 million miles
from the Sun.
425
00:23:31,200 --> 00:23:35,700
The distances beyond Mars are
about to get much, much larger.
426
00:23:41,127 --> 00:23:42,795
- Here we are—Jupiter.
427
00:23:42,795 --> 00:23:46,089
- We're at 484 feet
from the Sun.
428
00:23:46,090 --> 00:23:50,590
- That's actually three times
as far from the Sun as Mars is.
429
00:23:50,929 --> 00:23:54,682
Narrator: With all this space
between these tiny marbles,
430
00:23:54,682 --> 00:23:59,144
it's a wonder we can see
the planets from Earth at all.
431
00:23:59,145 --> 00:24:03,315
- It tells us that the Sun is
incredibly bright
432
00:24:03,316 --> 00:24:06,319
so that the light from the Sun
can go out to these bodies,
433
00:24:06,319 --> 00:24:07,486
reflect off them,
434
00:24:07,487 --> 00:24:09,071
and then come back
to here on Earth
435
00:24:09,072 --> 00:24:10,907
for us to see them.
436
00:24:10,907 --> 00:24:13,576
Okay, onwards and outwards
to Saturn.
437
00:24:13,576 --> 00:24:16,912
- All right, here we go.
438
00:24:16,913 --> 00:24:18,915
Narrator:
Our two space explorers
439
00:24:18,915 --> 00:24:23,415
find Saturn 886 feet
from the Sun.
440
00:24:23,670 --> 00:24:25,922
- In fact, Saturn,
441
00:24:25,922 --> 00:24:29,926
at 886 million miles away
from the Sun,
442
00:24:29,926 --> 00:24:32,637
is almost twice the distance
from the Sun
443
00:24:32,637 --> 00:24:34,722
that Jupiter is from the Sun.
444
00:24:34,722 --> 00:24:36,682
So we've come
a huge extra distance,
445
00:24:36,683 --> 00:24:40,937
and we're not even done
with the solar system yet.
446
00:24:40,937 --> 00:24:44,899
Narrator: At 1,800 feet,
the scaled orbit of Uranus
447
00:24:44,899 --> 00:24:48,277
stands twice as far as Saturn,
448
00:24:48,277 --> 00:24:52,777
1.8 billion miles from the Sun.
449
00:24:53,491 --> 00:24:56,452
- I can hardly see
the Sun back there.
450
00:24:56,452 --> 00:24:59,997
And I can actually hardly see
Neptune in the distance,
451
00:24:59,998 --> 00:25:02,792
which is our next stop
on our journey.
452
00:25:02,792 --> 00:25:05,628
Shall we go?
- Let's go.
453
00:25:09,799 --> 00:25:11,842
- Jeez, that's far.
-Yep.
454
00:25:11,843 --> 00:25:16,055
- [laughs]
455
00:25:16,055 --> 00:25:18,557
And here we are—Neptune-
456
00:25:18,558 --> 00:25:19,642
the last of the planets.
457
00:25:19,642 --> 00:25:23,479
- 2,798 feet from our Sun.
458
00:25:23,479 --> 00:25:26,690
- That from our model translates
into the real-world distance
459
00:25:26,691 --> 00:25:28,859
of almost 3 billion miles
460
00:25:28,860 --> 00:25:31,612
that Neptune is away
from the Sun.
461
00:25:31,612 --> 00:25:35,198
This far out,
a planet takes a long time
462
00:25:35,199 --> 00:25:37,201
to do an orbit around the Sun.
463
00:25:37,201 --> 00:25:41,701
The Neptunian year is about
165 of our Earth years.
464
00:25:42,915 --> 00:25:46,835
In fact, only one of those
Neptunian years has passed
465
00:25:46,836 --> 00:25:49,004
since Neptune
was actually discovered.
466
00:25:49,005 --> 00:25:51,507
Narrator:
Viewed on this scale,
467
00:25:51,507 --> 00:25:56,007
it's a wonder the Sun's gravity
has any effect at all.
468
00:25:57,847 --> 00:26:02,347
And there's still more to
the solar system beyond Neptune,
469
00:26:02,602 --> 00:26:06,522
including smaller bodies,
like Pluto...
470
00:26:06,522 --> 00:26:09,066
and then,
nearly a light-year away,
471
00:26:09,067 --> 00:26:13,567
clouds of dark icy comets.
472
00:26:15,031 --> 00:26:18,284
If the space between the planets
in our solar system
473
00:26:18,284 --> 00:26:21,036
strains human comprehension,
474
00:26:21,037 --> 00:26:24,999
then the vast distances
between stars and galaxies
475
00:26:24,999 --> 00:26:28,502
totally overwhelms it.
476
00:26:28,503 --> 00:26:32,048
That astronomers even know
how far away stars are
477
00:26:32,048 --> 00:26:36,135
is a mystery to Nora
from Brooklyn, New York,
478
00:26:36,135 --> 00:26:39,972
who wants to...
479
00:26:45,228 --> 00:26:47,730
- Nora, that's actually
a pretty complex question.
480
00:26:47,730 --> 00:26:49,857
For the most nearby stars,
481
00:26:49,857 --> 00:26:53,485
we look at how their positions
in the sky change with time
482
00:26:53,486 --> 00:26:55,738
as Earth orbits the Sun.
483
00:26:55,738 --> 00:26:59,491
For more distant stars,
or stars in other galaxies,
484
00:26:59,492 --> 00:27:02,077
we measure how bright
they appear to be,
485
00:27:02,078 --> 00:27:04,413
compare that
with their known power,
486
00:27:04,413 --> 00:27:07,332
and thus determine
their distance.
487
00:27:09,752 --> 00:27:13,338
Narrator: They are distances
so immense that "how big"
488
00:27:13,339 --> 00:27:16,508
and "how far" are questions
to challenge
489
00:27:16,509 --> 00:27:20,095
anyone's power of comprehension.
490
00:27:20,096 --> 00:27:22,473
But the magnitudes
of the universe
491
00:27:22,473 --> 00:27:25,934
also extend to speed.
492
00:27:25,935 --> 00:27:29,104
What scientists have discovered
is that the universe
493
00:27:29,105 --> 00:27:31,774
is a super-velocity racetrack
494
00:27:31,774 --> 00:27:36,274
where even giant planets move
faster than speeding bullets.
495
00:27:39,866 --> 00:27:44,366
We've seen how big
and how far things are in space.
496
00:27:45,079 --> 00:27:48,665
Now we're going to see how fast.
497
00:27:48,666 --> 00:27:50,959
To do that, first,
we have to understand
498
00:27:50,960 --> 00:27:55,460
the celestial measuring stick
known as the light-year.
499
00:27:55,631 --> 00:27:57,174
Just like it sounds,
500
00:27:57,175 --> 00:28:01,675
one light-year is the distance
light travels in one year.
501
00:28:01,679 --> 00:28:05,516
That amounts
to about 6 trillion miles.
502
00:28:05,516 --> 00:28:07,226
But that doesn't help us
understand
503
00:28:07,226 --> 00:28:11,396
how fast light speed itself is.
504
00:28:11,397 --> 00:28:13,148
- The speed of light is
really fast—
505
00:28:13,149 --> 00:28:16,193
About 186,000 miles per second.
506
00:28:16,194 --> 00:28:18,905
Now that's hard to conceive
without an example.
507
00:28:18,905 --> 00:28:21,449
Imagine light were bouncing
back and forth
508
00:28:21,449 --> 00:28:23,492
between Los Angeles
and New York.
509
00:28:23,492 --> 00:28:27,992
It could do 38 back-and-forth
bounces in one second.
510
00:28:30,333 --> 00:28:32,668
Narrator: In an effort
to chase down the concept
511
00:28:32,668 --> 00:28:34,503
of the speed of light,
512
00:28:34,503 --> 00:28:36,296
astronomer Greg Laughlin
513
00:28:36,297 --> 00:28:39,008
teams with firearms expert
Michael Voigt
514
00:28:39,008 --> 00:28:43,220
to demonstrate some of the
fastest moving objects on Earth.
515
00:28:43,221 --> 00:28:44,972
[gunshot]
516
00:28:44,972 --> 00:28:48,475
- The way we're going to do that
is to compare the speed of light
517
00:28:48,476 --> 00:28:51,020
to the speed of something that's
really fast here on Earth,
518
00:28:51,020 --> 00:28:52,688
which are bullets.
519
00:28:54,857 --> 00:28:57,109
- We've got a target downrange,
so when it hits it,
520
00:28:57,109 --> 00:28:58,902
you'll hear that ding
on the end of it.
521
00:28:58,903 --> 00:29:01,530
And you can kind of see how long
that actually takes.
522
00:29:01,530 --> 00:29:03,323
This is a .204 Ruger.
523
00:29:03,324 --> 00:29:05,534
This is the fastest
commercial cartridge
524
00:29:05,534 --> 00:29:06,868
on the planet right now.
525
00:29:11,165 --> 00:29:13,709
- We've got a 300-yard travel,
526
00:29:13,709 --> 00:29:15,877
so I'm really going to try
to get a sense
527
00:29:15,878 --> 00:29:17,212
of the time that it takes
528
00:29:17,213 --> 00:29:20,216
for that bullet
to travel downrange.
529
00:29:20,216 --> 00:29:21,383
So let's see how that works.
530
00:29:21,384 --> 00:29:22,426
[gunshot]
531
00:29:22,426 --> 00:29:23,510
- Nice shot.
532
00:29:23,511 --> 00:29:24,553
[gunshot]
533
00:29:24,553 --> 00:29:26,304
- Boy, I couldn't get any sense.
534
00:29:26,305 --> 00:29:27,889
As soon as I pulled
the trigger—boom—
535
00:29:27,890 --> 00:29:29,057
It hit the target.
536
00:29:29,058 --> 00:29:31,685
No sense at all
of the travel time.
537
00:29:31,686 --> 00:29:34,605
[gunshots]
538
00:29:34,605 --> 00:29:36,189
Narrator:
Because it's so difficult
539
00:29:36,190 --> 00:29:40,569
for the human senses to perceive
the speed of these bullets,
540
00:29:40,569 --> 00:29:44,239
Mike sets up a highly accurate
timing device
541
00:29:44,240 --> 00:29:46,784
known as a chronograph.
542
00:29:46,784 --> 00:29:49,620
- So this is the unit
that the timer's actually in.
543
00:29:49,620 --> 00:29:51,413
Inside, it's got a clock.
544
00:29:51,414 --> 00:29:53,416
- Okay, it looks like
the chronograph's ready here.
545
00:29:53,416 --> 00:29:54,708
- All right.
546
00:29:54,709 --> 00:29:56,252
Let's put a couple rounds
through here,
547
00:29:56,252 --> 00:29:58,254
and we'll see how fast
this ammo goes.
548
00:30:04,302 --> 00:30:05,720
And what do we have?
549
00:30:05,720 --> 00:30:09,265
- Wow, so that was 4,297 feet
per second.
550
00:30:09,265 --> 00:30:13,394
So that's about 3,000 miles
per hour.
551
00:30:13,394 --> 00:30:15,062
- Pretty quick.
- Pretty quick.
552
00:30:15,062 --> 00:30:16,772
It's a little less than a mile
per second.
553
00:30:16,772 --> 00:30:19,232
That's roughly four times
the speed of sound.
554
00:30:19,233 --> 00:30:21,944
So, I mean, I'm impressed.
555
00:30:21,944 --> 00:30:25,280
But that pales in comparison
to the speed of light.
556
00:30:25,281 --> 00:30:27,950
In the time that it took
for those bullets to go
557
00:30:27,950 --> 00:30:29,451
from the muzzle of the gun
558
00:30:29,452 --> 00:30:31,370
all the way downrange
to hit the target,
559
00:30:31,370 --> 00:30:33,663
during that time,
light has enough time
560
00:30:33,664 --> 00:30:35,624
to go all the way around
the surface of the Earth
561
00:30:35,624 --> 00:30:38,293
from Los Angeles to Paris
and then back
562
00:30:38,294 --> 00:30:41,797
in that same amount of time.
563
00:30:41,797 --> 00:30:45,759
Narrator. Moving at
670 million miles per hour,
564
00:30:45,760 --> 00:30:50,260
light completely demolishes
any earthly experience of speed.
565
00:30:51,140 --> 00:30:53,559
- That really doesn't mean
very much to me,
566
00:30:53,559 --> 00:30:56,645
because the whole distance
of 670 million miles
567
00:30:56,645 --> 00:30:58,730
is much larger
than any kind of distances
568
00:30:58,731 --> 00:31:03,231
that we normally deal here
with on Earth.
569
00:31:03,486 --> 00:31:06,447
Narrator: The speed of light
and the speed of our world
570
00:31:06,447 --> 00:31:08,699
are so vastly far apart,
571
00:31:08,699 --> 00:31:12,160
we have to take light
and slow it down
572
00:31:12,161 --> 00:31:15,539
to really understand
the difference.
573
00:31:15,539 --> 00:31:19,543
For that, we go back
to the speeding bullet.
574
00:31:19,543 --> 00:31:21,419
At 3,000 miles per hour,
575
00:31:21,420 --> 00:31:25,048
we can barely perceive
its speed.
576
00:31:25,049 --> 00:31:28,510
If light moved no faster than
a speeding bullet,
577
00:31:28,511 --> 00:31:30,846
what would happen
to the world around us
578
00:31:30,846 --> 00:31:34,975
if we slowed it down
by the same amount?
579
00:31:34,975 --> 00:31:37,310
For example, a commercial jet
580
00:31:37,311 --> 00:31:40,814
travels roughly 600 miles
an hour.
581
00:31:40,815 --> 00:31:44,819
So assuming the bullet
represents the speed of light,
582
00:31:44,819 --> 00:31:47,488
how slow would the jet look?
583
00:31:47,488 --> 00:31:49,406
- At the scale
where the speed of light is
584
00:31:49,407 --> 00:31:51,033
3,000 miles per hour,
585
00:31:51,033 --> 00:31:53,827
then that commercial jet
is crawling along
586
00:31:53,828 --> 00:31:55,454
so that it would take
an entire minute
587
00:31:55,454 --> 00:31:59,954
to travel 3 inches.
588
00:32:00,376 --> 00:32:04,004
Narrator: An F-15
can reach mach M.5.
589
00:32:04,004 --> 00:32:07,716
That's over 1,500 miles
per hour.
590
00:32:07,716 --> 00:32:10,176
But on this slow-light scale,
591
00:32:10,177 --> 00:32:14,677
an F-15 needs a full minute
to move 7 inches.
592
00:32:16,684 --> 00:32:19,728
And what about speeding bullets
themselves?
593
00:32:19,728 --> 00:32:24,228
How slow do they look
on this slow-light scale?
594
00:32:24,733 --> 00:32:27,068
[gunshot]
595
00:32:27,069 --> 00:32:29,321
- If we go up to those
high-speed rifle bullets,
596
00:32:29,321 --> 00:32:32,073
then they're making it just
a little bit more than a foot,
597
00:32:32,074 --> 00:32:35,077
about 13 inches
over the course of one minute
598
00:32:35,077 --> 00:32:38,914
at the scale
where the 3,000 miles per hour
599
00:32:38,914 --> 00:32:41,708
is the actual speed of light.
600
00:32:41,709 --> 00:32:43,293
Narrator:
In the real world,
601
00:32:43,294 --> 00:32:47,794
a snail moves
more than twice as fast.
602
00:32:49,383 --> 00:32:52,344
As it turns out,
much of the cosmos
603
00:32:52,344 --> 00:32:56,844
is zipping around at speeds
we can't really comprehend.
604
00:32:59,268 --> 00:33:01,687
- Motion is actually
the normal state of affairs
605
00:33:01,687 --> 00:33:03,063
in the universe.
606
00:33:03,063 --> 00:33:04,606
We may think
we're standing still—
607
00:33:04,607 --> 00:33:06,442
And we are,
relative to the ground—
608
00:33:06,442 --> 00:33:08,527
But Earth is orbiting the Sun,
609
00:33:08,527 --> 00:33:11,279
the Sun is orbiting around
the center of our galaxy,
610
00:33:11,280 --> 00:33:15,780
our galaxy is orbiting around
in our local group of galaxies.
611
00:33:16,619 --> 00:33:18,621
Narrator: And all
of these objects are moving
612
00:33:18,621 --> 00:33:23,121
at very high speeds.
613
00:33:23,167 --> 00:33:24,793
- The Earth is orbiting the Sun
614
00:33:24,793 --> 00:33:29,214
at a speed of about 66,000 miles
per hour.
615
00:33:29,215 --> 00:33:32,593
That's enough to take you
around the Earth more than twice
616
00:33:32,593 --> 00:33:35,637
in a single hour.
617
00:33:35,638 --> 00:33:38,682
Narrator: Our Sun is rushing
around the Milky Way center
618
00:33:38,682 --> 00:33:42,811
at 483,000 miles per hour.
619
00:33:42,811 --> 00:33:45,939
And the Milky Way itself
is flying through space
620
00:33:45,940 --> 00:33:50,440
at 1.3 million miles per hour.
621
00:33:50,736 --> 00:33:55,236
But the speed of light is still
over 600 times faster.
622
00:33:57,326 --> 00:33:59,494
The simple fact remains,
623
00:33:59,495 --> 00:34:01,747
we live in slow motion
624
00:34:01,747 --> 00:34:05,375
compared to the nature
of the cosmos.
625
00:34:05,376 --> 00:34:07,336
Modern technology doesn't travel
626
00:34:07,336 --> 00:34:10,630
anywhere near
the speed of light.
627
00:34:10,631 --> 00:34:13,800
- If we travel, say,
at commercial-jet speed,
628
00:34:13,801 --> 00:34:17,763
which is a million times slower
than the speed of light,
629
00:34:17,763 --> 00:34:20,015
then it's going to take us
of order 4 million years
630
00:34:20,015 --> 00:34:24,515
to traverse that distance
to the closest stars to the Sun.
631
00:34:27,439 --> 00:34:30,233
Narrator: If it takes more years
to reach the nearest star
632
00:34:30,234 --> 00:34:33,362
than the human race has existed,
633
00:34:33,362 --> 00:34:36,406
how can any person
ever really understand
634
00:34:36,407 --> 00:34:39,201
the size of our own galaxy?
635
00:34:43,497 --> 00:34:46,750
By downsizing
the biggest planets and stars
636
00:34:46,750 --> 00:34:48,376
and the velocity of light speed
637
00:34:48,377 --> 00:34:51,546
to the level
of human experience,
638
00:34:51,547 --> 00:34:53,465
we can finally begin
to understand
639
00:34:53,465 --> 00:34:57,552
some of the scales
of outer space.
640
00:34:57,553 --> 00:34:59,805
But is there a way
to do the same
641
00:34:59,805 --> 00:35:03,058
for the distances
between the stars...
642
00:35:03,058 --> 00:35:07,558
distances that utterly dwarf
the human imagination?
643
00:35:08,564 --> 00:35:11,108
Although scientists measure
the enormous distance
644
00:35:11,108 --> 00:35:13,985
between stars in light-years,
645
00:35:13,986 --> 00:35:16,488
those numbers
barely help us grasp
646
00:35:16,488 --> 00:35:20,408
the expansive nature
of the galactic landscape.
647
00:35:20,409 --> 00:35:24,909
So let's shrink everything down
to a scale where one light-year
648
00:35:24,913 --> 00:35:27,582
equals one mile.
649
00:35:27,583 --> 00:35:30,043
On that scale,
our Sun shrinks down
650
00:35:30,044 --> 00:35:33,756
to the size of a sand grain.
651
00:35:33,756 --> 00:35:37,134
- We've calculated
just how many sand grains,
652
00:35:37,134 --> 00:35:38,844
or how many stars,
653
00:35:38,844 --> 00:35:41,263
would fill
our own Milky Way Galaxy.
654
00:35:41,263 --> 00:35:43,306
And the number of stars
in the Milky Way
655
00:35:43,307 --> 00:35:47,807
is about the same as the number
of sand grains in this chest.
656
00:35:48,437 --> 00:35:49,771
Narrator: If you're counting,
657
00:35:49,772 --> 00:35:54,109
that's more than
100 billion stars.
658
00:35:54,109 --> 00:35:57,153
If one light-year
equals one mile,
659
00:35:57,154 --> 00:35:59,614
where is the nearest star?
660
00:35:59,615 --> 00:36:00,824
From the vantage point
661
00:36:00,824 --> 00:36:03,493
of the Griffith Observatory
in Los Angeles,
662
00:36:03,494 --> 00:36:06,121
where astronomer
Laura Danly works,
663
00:36:06,121 --> 00:36:09,749
the nearest sand grain
would end up in Hollywood,
664
00:36:09,750 --> 00:36:13,587
4 miles away.
665
00:36:13,587 --> 00:36:15,380
To help pinpoint sand grains
666
00:36:15,381 --> 00:36:18,801
positioned four miles apart
in a dense city,
667
00:36:18,801 --> 00:36:20,886
we'll use mirrors
to flash sunlight
668
00:36:20,886 --> 00:36:23,889
back and forth between them.
669
00:36:23,889 --> 00:36:25,849
- So Aaron and Johnny
have mirrors,
670
00:36:25,849 --> 00:36:28,977
and they're going to reflect
sunlight to help us see
671
00:36:28,977 --> 00:36:31,562
just how far away it is
to the nearest star.
672
00:36:31,563 --> 00:36:36,063
So I need to get a few stars to
take off to Hollywood with me.
673
00:36:37,111 --> 00:36:38,112
That should do.
674
00:36:38,112 --> 00:36:39,571
So, Stan, Aaron, are you ready?
675
00:36:39,571 --> 00:36:40,738
You're going to be the Sun
676
00:36:40,739 --> 00:36:42,615
staying here
at Griffith Observatory.
677
00:36:42,616 --> 00:36:44,242
Johnny and I are headed out
to Hollywood.
678
00:36:44,243 --> 00:36:45,244
You all set?
679
00:36:45,244 --> 00:36:46,286
- Let's do it.
680
00:36:46,286 --> 00:36:49,122
- All right, let's go.
681
00:36:49,123 --> 00:36:52,000
Narrator: The nearest
celestial neighbor to our Sun
682
00:36:52,000 --> 00:36:56,500
isn't a single star
but rather a grouping of three.
683
00:36:57,172 --> 00:37:00,633
Two of them—
Alpha Centauri A and B—
684
00:37:00,634 --> 00:37:02,010
Orbit each other
685
00:37:02,010 --> 00:37:05,596
and are about the same size
as our Sun.
686
00:37:05,597 --> 00:37:09,809
The third, Proxima Centauri,
is a red dwarf star,
687
00:37:09,810 --> 00:37:14,310
dim and only about 10%
as massive as its siblings.
688
00:37:22,865 --> 00:37:24,825
- I'm here on a rooftop
in Hollywood,
689
00:37:24,825 --> 00:37:27,118
about four miles away
from Griffith Observatory
690
00:37:27,119 --> 00:37:28,745
there in the background.
691
00:37:28,746 --> 00:37:31,248
I have in my hand
a bag full of stars.
692
00:37:31,248 --> 00:37:34,793
I'm going to take out
three sand grains—
693
00:37:34,793 --> 00:37:37,045
One, two, three—
694
00:37:37,045 --> 00:37:38,588
Throw the rest away—
695
00:37:38,589 --> 00:37:41,341
That represent
our nearest stars.
696
00:37:41,341 --> 00:37:44,677
Proxima Centauri is actually
the closest star to Earth.
697
00:37:44,678 --> 00:37:46,221
And on the scale
of this analogy,
698
00:37:46,221 --> 00:37:47,889
it's about 70 feet behind me,
699
00:37:47,890 --> 00:37:49,892
so we'll just toss
Proxima Centauri
700
00:37:49,892 --> 00:37:51,393
to its proper place.
701
00:37:51,393 --> 00:37:55,397
Alpha Centauri A
and Alpha Centauri B
702
00:37:55,397 --> 00:37:58,525
on this scale might be
about two feet apart,
703
00:37:58,525 --> 00:38:03,025
while our Sun is four miles away
at Griffith Observatory.
704
00:38:04,448 --> 00:38:06,241
Narrator: From here,
705
00:38:06,241 --> 00:38:08,618
the sand grain
representing our Sun
706
00:38:08,619 --> 00:38:11,705
will be impossible to spot.
707
00:38:11,705 --> 00:38:15,250
This is where the mirrors
come in.
708
00:38:15,250 --> 00:38:16,918
- Here we are at Alpha Centauri,
709
00:38:16,919 --> 00:38:19,254
but now we have to find
our own Sun.
710
00:38:19,254 --> 00:38:23,754
Let's see if we can't get them
to show us the Sun.
711
00:38:24,259 --> 00:38:25,593
[cell phone rings]
712
00:38:25,594 --> 00:38:27,262
- Hello, it's Stan.
713
00:38:27,262 --> 00:38:29,681
- Hey, Stan,
we can't see the Sun.
714
00:38:29,681 --> 00:38:31,724
You want to send us
a little sunlight our way?
715
00:38:31,725 --> 00:38:36,225
- Okay, Sun's coming your way.
716
00:38:36,605 --> 00:38:38,732
- Can't see it yet.
717
00:38:38,732 --> 00:38:41,985
Uh, there.
That was a good one, yeah.
718
00:38:41,985 --> 00:38:43,111
Nice and bright.
719
00:38:43,111 --> 00:38:44,821
Wow, look at that.
720
00:38:44,822 --> 00:38:46,949
That's incredible.
721
00:38:46,949 --> 00:38:49,034
Okay, Stan,
we're going to show you
722
00:38:49,034 --> 00:38:52,871
the light of Alpha Centauri now.
723
00:38:52,871 --> 00:38:54,122
- Yes, yes.
There it is.
724
00:38:54,122 --> 00:38:55,623
Yep, we saw it.
725
00:38:55,624 --> 00:38:56,958
- They got it.
- Awesome.
726
00:38:56,959 --> 00:39:01,088
- He sees Alpha Centauri.
727
00:39:01,088 --> 00:39:03,632
Narrator: In our region
of the Milky Way Galaxy,
728
00:39:03,632 --> 00:39:06,509
the typical distance
between stars
729
00:39:06,510 --> 00:39:10,597
ranges from three to five
light-years.
730
00:39:10,597 --> 00:39:14,142
With stars the size
of sand grains,
731
00:39:14,142 --> 00:39:18,642
we could fit about 20 in a city
like Los Angeles.
732
00:39:19,147 --> 00:39:23,568
But if more stars crowded
any closer to Earth,
733
00:39:23,569 --> 00:39:26,446
our cosmic neighborhood
would become hazardous
734
00:39:26,446 --> 00:39:28,656
to life as we know it.
735
00:39:28,657 --> 00:39:30,784
[explosion rumbling]
736
00:39:30,784 --> 00:39:32,202
- Supernova going off,
737
00:39:32,202 --> 00:39:35,705
which would really cook
the atmosphere.
738
00:39:35,706 --> 00:39:40,168
And if another star were to pass
too close to the Sun,
739
00:39:40,168 --> 00:39:43,212
then the planetary orbits
would be badly perturbed.
740
00:39:43,213 --> 00:39:44,839
Planets could even be lost
from the Sun
741
00:39:44,840 --> 00:39:47,592
and sent out
into interstellar space.
742
00:39:47,593 --> 00:39:50,137
It's really true that if we
didn't have these vast amounts
743
00:39:50,137 --> 00:39:52,139
of real estate
between the stars,
744
00:39:52,139 --> 00:39:56,101
we likely wouldn't even be here.
745
00:39:56,101 --> 00:39:59,187
Narrator: Cutting down the
distance light travels in a year
746
00:39:59,187 --> 00:40:02,690
helps put stars
in a clearer context.
747
00:40:02,691 --> 00:40:05,402
But can we do the same
to grapple with
748
00:40:05,402 --> 00:40:07,695
the practically infinite
dimensions
749
00:40:07,696 --> 00:40:11,282
of the universe itself?
750
00:40:11,283 --> 00:40:15,783
The Milky Way spans
100,000 light-years across.
751
00:40:15,871 --> 00:40:20,371
And the next galaxy over is
really, really far away.
752
00:40:21,627 --> 00:40:23,795
- The distance to the nearest
galaxy like our own—
753
00:40:23,795 --> 00:40:26,380
The nearest spiral galaxy,
the Andromeda Galaxy—
754
00:40:26,381 --> 00:40:29,217
Is about 2.5 million
light-years away.
755
00:40:29,217 --> 00:40:31,886
That's about almost 25 times
756
00:40:31,887 --> 00:40:34,097
the size
of the Milky Way itself.
757
00:40:34,097 --> 00:40:36,849
So if you lined up
25 Milky Ways end on end,
758
00:40:36,850 --> 00:40:40,812
that would stretch
to the Andromeda Galaxy.
759
00:40:40,812 --> 00:40:44,315
Narrator: It might be clearer
to scale things down some more
760
00:40:44,316 --> 00:40:47,068
and imagine galaxies
as urban centers
761
00:40:47,069 --> 00:40:50,781
spread out
across the United States.
762
00:40:50,781 --> 00:40:52,866
- Sometimes galaxies are
referred to as star cities,
763
00:40:52,866 --> 00:40:55,535
and that's
a pretty good analogy.
764
00:40:55,535 --> 00:40:57,912
Narrator: If we envision
the Milky Way Galaxy
765
00:40:57,913 --> 00:41:01,124
at the size of the Los Angeles
metropolitan area,
766
00:41:01,124 --> 00:41:03,918
roughly 100 miles wide,
767
00:41:03,919 --> 00:41:07,297
then Andromeda would be
in New York.
768
00:41:07,297 --> 00:41:09,173
In between
would be other members
769
00:41:09,174 --> 00:41:13,674
of what astronomers call
the "local group” of galaxies.
770
00:41:14,388 --> 00:41:16,765
- There's basically two major
players in the local group.
771
00:41:16,765 --> 00:41:18,933
There's our galaxy—
the Milky Way Galaxy—
772
00:41:18,934 --> 00:41:21,102
And there's
the Andromeda Galaxy.
773
00:41:21,103 --> 00:41:24,940
There's another smaller
spiral galaxy knows as M33.
774
00:41:24,940 --> 00:41:27,442
And then we also have
these dwarf galaxies,
775
00:41:27,442 --> 00:41:31,942
which contain 100 million stars,
sometimes even fewer.
776
00:41:32,114 --> 00:41:34,199
Narrator:
But even the vast distances
777
00:41:34,199 --> 00:41:37,035
that separate members
of the local group
778
00:41:37,035 --> 00:41:41,039
won't be enough to save
our home galaxy.
779
00:41:41,039 --> 00:41:45,293
- Andromeda and M33 are both
headed toward the Milky Way,
780
00:41:45,293 --> 00:41:47,628
to the point where,
in a few billion years from now,
781
00:41:47,629 --> 00:41:50,173
they're going to have
a close encounter.
782
00:41:50,173 --> 00:41:54,673
Narrator: On a cosmic scale,
the collision seems violent.
783
00:41:54,678 --> 00:41:57,430
But in fact,
the stars in the galaxies
784
00:41:57,431 --> 00:41:59,891
are so widely spaced,
785
00:41:59,891 --> 00:42:04,391
they will weave past each other,
largely undisturbed.
786
00:42:04,771 --> 00:42:07,023
If humans survive that long,
787
00:42:07,024 --> 00:42:10,777
they'll hardly notice it
here on Earth.
788
00:42:10,777 --> 00:42:12,653
- And a few billion years
after that,
789
00:42:12,654 --> 00:42:15,239
they'll have merged
into a single galaxy.
790
00:42:15,240 --> 00:42:17,825
Narrator. The Milky Way
as we know it
791
00:42:17,826 --> 00:42:21,788
will cease to exist.
792
00:42:21,788 --> 00:42:24,081
Until that time comes, though,
793
00:42:24,082 --> 00:42:27,502
the distances between
even the nearest galaxies
794
00:42:27,502 --> 00:42:31,839
of the local group
remain beyond our grasp.
795
00:42:31,840 --> 00:42:35,969
And our galactic neighbors
represent only a small sliver
796
00:42:35,969 --> 00:42:39,263
of our immense cosmos.
797
00:42:39,264 --> 00:42:41,224
- In the observable part
of the universe,
798
00:42:41,224 --> 00:42:44,727
there's something like
100 billion galaxies,
799
00:42:44,728 --> 00:42:47,772
each with billions of stars.
800
00:42:47,773 --> 00:42:50,650
Narrator: If galaxies
were spaced out
801
00:42:50,650 --> 00:42:54,862
like urban centers
throughout the United States,
802
00:42:54,863 --> 00:42:58,867
then to approximate the size
of the observable universe,
803
00:42:58,867 --> 00:43:01,286
the country
would have to be large enough
804
00:43:01,286 --> 00:43:05,707
to wrap around the Earth
about 500 times.
805
00:43:10,128 --> 00:43:12,880
Shrinking the universe
down to human scale
806
00:43:12,881 --> 00:43:16,009
may help us comprehend its size,
807
00:43:16,009 --> 00:43:20,509
but reality, of course,
doesn't work that way.
808
00:43:20,680 --> 00:43:22,348
- The vastness of the universe
809
00:43:22,349 --> 00:43:24,351
sometimes makes us feel
really small.
810
00:43:24,351 --> 00:43:26,227
We're small compared
to the solar system,
811
00:43:26,228 --> 00:43:28,146
small compared to our galaxy,
812
00:43:28,146 --> 00:43:29,897
compared to the universe
as a whole.
813
00:43:29,898 --> 00:43:33,067
But in some ways, I think
we're not insignificant,
814
00:43:33,068 --> 00:43:36,446
because we're the only creatures
we know of
815
00:43:36,446 --> 00:43:39,991
that have the advanced minds
and curiosity and intellect
816
00:43:39,991 --> 00:43:41,742
to think about the universe.
817
00:43:41,743 --> 00:43:45,747
In a sense, we are the way
in which the universe has found
818
00:43:45,747 --> 00:43:48,833
to know itself.
819
00:43:48,834 --> 00:43:50,377
Narrator: And so that must mean
820
00:43:50,377 --> 00:43:53,588
the universe is finally starting
to figure out
821
00:43:53,588 --> 00:43:58,088
how awe-inspiringly vast
it truly is.
64506
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