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I want to talk to you about something

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kind of big.

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We'll start here.

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Sixty-five million years ago --

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(Laughter)

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the dinosaurs had a bad day.

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(Laughter)

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A chunk of rock six miles across,

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moving something like 50 times
the speed of a rifle bullet,

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slammed into the Earth.

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It released its energy all at once,

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and it was an explosion
that was mind-numbing.

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If you took every
nuclear weapon ever built

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at the height of the Cold War,

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lumped them together,

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and blew them up at the same time,

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that would be one one-millionth
of the energy released at that moment.

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The dinosaurs had a really bad day.

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OK?

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Now, a six-mile-wide rock is very large.

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We all live here in Boulder.

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If you look out your window
and see Longs Peak --

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you're probably familiar with it --

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now, scoop up Longs Peak
and put it out in space.

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Take ... Meeker, Mt. Meeker.

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Lump that in there,
and put that in space as well.

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And Mt. Everest. And K2.

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And the Indian peaks.

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Then you're starting to get an idea
of how much rock we're talking about, OK?

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We know it was that big

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because of the impact it had
and the crater it left.

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It hit in what we now know
as Yucatan, the Gulf of Mexico.

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You can see here,
there's the Yucatan Peninsula,

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if you recognize Cozumel
off the east coast there.

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Here is how big of a crater was left.

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It was huge.

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To give you a sense
of the scale ... there you go.

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The scale here is 50 miles on top,
a hundred kilometers on the bottom.

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This thing was 300 kilometers
across -- 200 miles --

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an enormous crater that excavated
out vast amounts of earth

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that splashed around the globe
and set fires all over the planet,

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threw up enough dust to block out the sun.

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It wiped out 75 percent
of all species on Earth.

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Now, not all asteroids are that big.

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Some of them are smaller.

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Here is one that came in

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over the United States in October of 1992.

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It came in on a Friday night.

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Why is that important?

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Because back then, video cameras
were just starting to become popular,

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and parents would bring them
to their kids' football games

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to film their kids playing football.

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And since this came in on a Friday,

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they were able to get this great footage
of this thing breaking up

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as it came in over West Virginia,
Maryland, Pennsylvania and New Jersey

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until it did that

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to a car in New York.

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(Laughter)

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Now, this is not a 200-mile-wide crater,

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but then again, you can see the rock,
which is sitting right here,

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about the size of a football,

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that hit that car and did that damage.

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Now, this thing was probably
about the size of a school bus

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when it first came in.

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It broke up through atmospheric pressure,

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it crumbled, and then
the pieces fell apart

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and did some damage.

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Now, you wouldn't want that falling
on your foot or your head,

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because it would do that to it.

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That would be bad.

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But it won't wipe out, you know,
all life on Earth, so that's fine.

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But it turns out, you don't need
something six miles across

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to do a lot of damage.

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There is a median point
between tiny rock and gigantic rock,

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and in fact, if any of you
have ever been to near Winslow, Arizona,

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there is a crater in the desert
there that is so iconic

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that it is actually
called "Meteor Crater."

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To give you a sense of scale,
this is about a mile wide.

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If you look up at the top,
that's a parking lot,

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and those are recreational
vehicles right there.

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So it's about a mile across,
600 feet deep.

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The object that formed this
was probably about 30 to 50 yards across,

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so roughly the size
of Macky Auditorium here.

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It came in at speeds that were tremendous,

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slammed into the ground, blew up,

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and exploded with the energy of roughly
a 20-megaton nuclear bomb --

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a very hefty bomb.

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This was 50,000 years ago,

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so it may have wiped out
a few buffalo or antelope,

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or something like that out in the desert,

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but it probably would not have caused
global devastation.

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It turns out that these things
don't have to hit the ground

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to do a lot of damage.

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Now, in 1908, over Siberia,
near the Tunguska region --

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for those of you who are Dan Aykroyd fans
and saw "Ghostbusters,"

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when he talked about the greatest
cross-dimensional rift

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since the Siberia blast of 1909,

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where he got the date
wrong, but that's OK.

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(Laughter)

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It was 1908. That's fine.
I can live with that.

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(Laughter)

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Another rock came
into the Earth's atmosphere

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and this one blew up above the ground,

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several miles up
above the surface of the Earth.

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The heat from the explosion
set fire to the forest below it,

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and then the shock wave came down
and knocked down trees

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for hundreds of square miles.

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This did a huge amount of damage.

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And again, this was a rock
probably roughly the size

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of this auditorium that we're sitting in.

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In Meteor Crater, it was made of metal,

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and metal is much tougher,
so it made it to the ground.

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The one over Tunguska
was probably made of rock,

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and that's much more crumbly,
so it blew up in the air.

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Either way, these are tremendous
explosions -- 20 megatons.

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Now, when these things blow up,

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they're not going to do
global ecological damage.

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They're not going to do
something like the dinosaur killer did.

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They're just not big enough.

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But they will do global economic damage,

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because they don't have
to hit, necessarily,

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to do this kind of damage.

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They don't have to do global devastation.

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If one of these things were to hit
pretty much anywhere,

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it would cause a panic.

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But if it came over a city,
an important city --

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not that any city
is more important than others,

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but some of them we depend on more
on the global economic basis --

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that could do a huge amount of damage
to us as a civilization.

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So, now that I've scared
the crap out of you --

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(Laughter)

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what can we do about this?

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This is a potential threat.

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Let me note that we have not had
a giant impact like the dinosaur killer

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for 65 million years.

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They're very rare.

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The smaller ones happen more often,

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but probably on the order of a millennium,

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every few centuries
or every few thousand years.

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But it's still something to be aware of.

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Well, what do we do about them?

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The first thing
we have to do is find them.

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This is an image of an asteroid
that passed us in 2009.

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It's right here.

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But you can see that it's extremely faint.

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I don't know if you can see that
in the back row.

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These are just stars.

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This is a rock
that was about 30 yards across,

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so roughly the size of the ones
that blew up over Tunguska

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and hit Arizona 50,000 years ago.

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These things are faint.

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They're hard to see,
and the sky is really big.

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We have to find these things first.

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Well, the good news is,
we're looking for them.

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NASA has devoted money to this;

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the National Science Foundation
and other countries

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are interested in doing this.

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We're building telescopes
that are looking for the threat.

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That's a great first step.
But what's the second step?

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The second step is if we see one heading
toward us, we have to stop it.

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What do we do?

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You've probably heard
about the asteroid Apophis.

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If you haven't yet, you will.

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If you've heard about the Mayan
2012 apocalypse,

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you're going to hear about Apophis,

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because you're keyed in
to all the doomsday networks, anyway.

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(Laughter)

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Apophis is an asteroid
that was discovered in 2004.

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It's roughly 250 [meters] across,
so it's pretty big --

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bigger than a football stadium.

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And it's going to pass
by the Earth in April of 2029.

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And it's going to pass us so close

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that it's actually going to come
underneath our weather satellites.

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The Earth's gravity is going to bend
the orbit of this thing so much

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that if it's just right,

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if it passes through this region of space,

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this kidney-bean-shaped region
called the keyhole,

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the Earth's gravity will bend it
just enough that seven years later,

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on April 13 -- which is a Friday,
I'll note -- in the year 2036 --

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(Laughter)

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you can't plan that kind of stuff --

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(Laughter)

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Apophis is going to hit us.

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And it's 250 meters across,
so it would do unbelievable damage.

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The good news is that the odds of it
actually passing through this keyhole

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and hitting us next go-around
are one in a million, roughly --

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very, very low odds.

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So I personally am not lying awake
at night worrying about this at all.

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I don't think Apophis is a problem.

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In fact, Apophis
is a blessing in disguise,

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because it woke us up
to the dangers of these things.

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This thing was discovered
just a few years ago

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and could hit us a few years from now.

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It won't, but it gives us a chance
to study these kinds of asteroids.

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We didn't really necessarily understand
these keyholes, and now we do,

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and it turns out that's really important,

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because how do you stop
an asteroid like this?

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Well, let me ask you:

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What happens if you're standing
in the road and a car's headed for you?

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What do you do?

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You do this. Right?
Move, and the car goes past you.

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But we can't move the Earth,
at least not easily,

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but we can move a small asteroid.

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And it turns out, we've even done it.

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In the year 2005, NASA launched
a probe called Deep Impact,

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which slammed a piece of itself
into the nucleus of a comet.

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Comets are very much like asteroids.

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The purpose wasn't to push it
out of the way;

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the purpose was to make a crater
to excavate the material

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and see what was underneath
the surface of this comet,

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which we learned quite a bit about.

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We did move the comet a little tiny bit --

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not very much, but that wasn't the point.

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However, think about this:

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This thing is orbiting the Sun
at 10, 20 miles per second.

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We shot a space probe
at it and hit it, OK?

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Imagine how hard that must be,
and we did it.

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That means we can do it again.

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If we see an asteroid that's coming
toward us, headed right for us,

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and we have two years to go?

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Boom! We hit it.

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You know, if you watch the movies --

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(Laughter)

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you might think:

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Why don't we use a nuclear weapon?

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Well, you can try that,
but the problem is timing.

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Shoot a nuclear weapon at this thing,

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you have to blow it up
within a few milliseconds of tolerance,

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or else you'll miss it.

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And there are a lot of other problems
with that; it's very hard to do.

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But just hitting something?
That's pretty easy.

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I think even NASA can do that,
and proved that they can.

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00:10:02,747 --> 00:10:03,756
(Laughter)

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The problem is, if you hit this asteroid,
you've changed the orbit,

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you measure the orbit,

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then you find out, oh yeah,
we just pushed it into a keyhole,

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and now it's going to hit us
in three years.

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Well, my opinion is: fine!

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It's not hitting us in six months --

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that's good.

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Now we have three years
to do something else.

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And you can hit it again.

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That's kind of ham-fisted;

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you might just push it
into a third keyhole or whatever,

245
00:10:26,903 --> 00:10:28,076
so you don't do that.

246
00:10:28,100 --> 00:10:29,271
And this is the part --

247
00:10:29,766 --> 00:10:31,066
it's the part I just love.

248
00:10:31,090 --> 00:10:33,705
(Laughter)

249
00:10:33,729 --> 00:10:38,187
After the big macho "Grr ... bam!
We're gonna hit this thing in the face,"

250
00:10:38,211 --> 00:10:41,009
then we bring in the velvet gloves.

251
00:10:41,033 --> 00:10:42,876
(Laughter)

252
00:10:42,900 --> 00:10:45,789
There's a group of scientists
and engineers and astronauts,

253
00:10:45,813 --> 00:10:48,246
and they call themselves
The B612 Foundation.

254
00:10:48,270 --> 00:10:50,616
For those of you who've read
"The Little Prince,"

255
00:10:50,640 --> 00:10:52,608
you understand that reference, I hope --

256
00:10:52,632 --> 00:10:55,087
the little prince lived
on an asteroid called B612.

257
00:10:55,111 --> 00:10:58,823
These are smart guys -- men and women --
astronauts, like I said, engineers.

258
00:10:58,847 --> 00:11:02,107
Rusty Schweickart, who was an Apollo 9
astronaut, is on this.

259
00:11:02,131 --> 00:11:04,250
Dan Durda, my friend who made this image,

260
00:11:04,274 --> 00:11:08,181
works here at Southwest Research Institute
in Boulder, on Walnut Street.

261
00:11:08,205 --> 00:11:09,740
He created this image for this.

262
00:11:09,764 --> 00:11:12,418
He's actually one of the astronomers
who works for them.

263
00:11:12,442 --> 00:11:15,045
If we see an asteroid
that's going to hit the Earth

264
00:11:15,069 --> 00:11:16,782
and we have enough time,

265
00:11:16,806 --> 00:11:19,161
we can hit it to move it
into a better orbit.

266
00:11:19,185 --> 00:11:23,986
But then what we do is launch a probe
that has to weigh a ton or two.

267
00:11:24,010 --> 00:11:26,996
It doesn't have to be huge --
a couple of tons, not that big --

268
00:11:27,020 --> 00:11:28,733
and you park it near the asteroid.

269
00:11:28,757 --> 00:11:32,088
You don't land on it, because these things
are tumbling end over end.

270
00:11:32,112 --> 00:11:33,708
It's very hard to land on them.

271
00:11:33,732 --> 00:11:34,894
Instead you get near it.

272
00:11:34,918 --> 00:11:37,142
The gravity of the asteroid
pulls on the probe,

273
00:11:37,166 --> 00:11:39,190
and the probe
has a couple of tons of mass.

274
00:11:39,214 --> 00:11:40,947
It has a little tiny bit of gravity,

275
00:11:40,971 --> 00:11:44,200
but it's enough
that it can pull the asteroid,

276
00:11:44,224 --> 00:11:45,849
and you have your rocket set up --

277
00:11:45,873 --> 00:11:48,742
you can barely see it here,
but there's rocket plumes --

278
00:11:48,766 --> 00:11:52,140
and these guys are connected
by their own gravity,

279
00:11:52,164 --> 00:11:55,712
and if you move the probe
very slowly -- very, very gently,

280
00:11:55,736 --> 00:12:00,759
you can very easily finesse that rock
into a safe orbit.

281
00:12:00,783 --> 00:12:03,908
You can even put in orbit
around the Earth where we could mine it,

282
00:12:03,932 --> 00:12:06,726
although that's a whole other thing;
I won't go into that.

283
00:12:06,750 --> 00:12:07,777
(Laughter)

284
00:12:07,801 --> 00:12:09,553
But we'd be rich!

285
00:12:09,577 --> 00:12:15,011
(Laughter)

286
00:12:15,035 --> 00:12:17,059
So think about this, right?

287
00:12:17,745 --> 00:12:21,033
There are these giant rocks flying
out there, and they're hitting us,

288
00:12:21,057 --> 00:12:22,579
and they're doing damage to us.

289
00:12:22,603 --> 00:12:24,412
But we've figured out how to do this,

290
00:12:24,436 --> 00:12:26,653
and all the pieces
are in place to do this.

291
00:12:26,677 --> 00:12:29,878
We have astronomers
with telescopes, looking for them.

292
00:12:29,902 --> 00:12:32,173
We have very, very smart people,

293
00:12:32,197 --> 00:12:35,589
who are concerned about this
and figuring out how to fix the problem,

294
00:12:35,613 --> 00:12:37,445
and we have the technology to do this.

295
00:12:37,469 --> 00:12:39,671
This probe actually can't use
chemical rockets.

296
00:12:39,695 --> 00:12:42,353
Chemical rockets provide
too much thrust, too much push.

297
00:12:42,377 --> 00:12:43,939
The probe would just shoot away.

298
00:12:43,963 --> 00:12:46,014
We invented something called an ion drive,

299
00:12:46,038 --> 00:12:48,592
which is a very, very,
very low-thrust engine.

300
00:12:48,616 --> 00:12:51,925
It generates the force a piece of paper
would have on your hand --

301
00:12:51,949 --> 00:12:55,913
incredibly light, but it can run
for months and years,

302
00:12:55,937 --> 00:12:58,267
providing that very gentle push.

303
00:12:58,291 --> 00:13:00,880
If anybody here is a fan
of the original "Star Trek,"

304
00:13:00,904 --> 00:13:03,699
they ran across an alien ship
that had an ion drive,

305
00:13:03,723 --> 00:13:06,415
and Spock said, "They're very
technically sophisticated.

306
00:13:06,439 --> 00:13:08,940
They're a hundred years
ahead of us with this drive."

307
00:13:08,964 --> 00:13:10,510
Yeah, we have an ion drive now.

308
00:13:10,534 --> 00:13:13,516
We don't have the Enterprise,
but we've got an ion drive now.

309
00:13:13,540 --> 00:13:15,486
(Laughter)

310
00:13:15,510 --> 00:13:17,626
(Applause)

311
00:13:17,650 --> 00:13:18,876
Spock.

312
00:13:18,900 --> 00:13:21,032
(Laughter)

313
00:13:21,056 --> 00:13:22,253
So ...

314
00:13:23,788 --> 00:13:25,432
That's the difference --

315
00:13:25,456 --> 00:13:28,393
that's the difference
between us and the dinosaurs.

316
00:13:28,417 --> 00:13:29,859
This happened to them.

317
00:13:30,638 --> 00:13:32,453
It doesn't have to happen to us.

318
00:13:32,477 --> 00:13:35,635
The difference
between the dinosaurs and us

319
00:13:35,659 --> 00:13:37,774
is that we have a space program

320
00:13:37,798 --> 00:13:39,520
and we can vote,

321
00:13:39,544 --> 00:13:41,876
and so we can change our future.

322
00:13:41,900 --> 00:13:43,537
(Laughter)

323
00:13:43,561 --> 00:13:45,653
We have the ability to change our future.

324
00:13:45,677 --> 00:13:47,654
Sixty-five million years from now,

325
00:13:47,678 --> 00:13:51,582
we don't have to have our bones
collecting dust in a museum.

326
00:13:51,606 --> 00:13:52,774
Thank you very much.

327
00:13:52,798 --> 00:13:55,804
(Applause)