kind of big.

我想和你們談談一件

We'll start here.

稱得上大的事情。

Sixty-five million years ago --

我們從這裡開始吧。

(Laughter)

六千五百萬年前

the dinosaurs had a bad day.

恐龍群過了相當糟糕的一天。

(Laughter)

（笑）

A chunk of rock six miles across,

一塊六英里的巨石,

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

以比子彈還快

slammed into the Earth.

50倍的速度

It released its energy all at once,

撞向了地球。

and it was an explosion that was mind-numbing.

它立刻就釋放了巨大的能量,

If you took every nuclear weapon ever built

那次爆炸真的可謂

at the height of the Cold War,

是無法想像。

lumped them together,

假如你把冷戰期間

and blew them up at the same time,

所製造的所有核武器

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

綁在一起

The dinosaurs had a really bad day.

同時起爆,

OK?

所釋放的能量

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

只有那時的一百萬分之一。

We all live here in Boulder.

恐龍真的是很倒楣啊。

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

明白麼?

you're probably familiar with it --

一個半徑六千米的巨石是相當大。

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

現在我們正居住在博爾德。

Take ... Meeker, Mt. Meeker.

假如你往窗外看,

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

你會看到你應該很熟悉的郎二峰。

And Mt. Everest. And K2.

好, 現在把它挖出來

And the Indian peaks.

丟到宇宙去。

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

好,順便帶上米克峰, 把它們綁在一起

We know it was that big

也丟到宇宙去,

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

再加上珠峰 和 k2,

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

還有印第安峰。

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

現在你就肯定在想

if you recognize Cozumel off the east coast there.

這石頭到底有多大啊?

Here is how big of a crater was left.

我們根據它留下來的彈坑

It was huge.

和所造成的衝擊斷定它十分巨大。

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

它在我們現在稱為尤卡坦半島

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

墨西哥灣的地方撞上了地球。

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

你可以看到這就是

an enormous crater that excavated out vast amounts of earth

尤卡坦半島, 假如你知道可租米爾島

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

的話, 它就在離里東海岸不遠處。

threw up enough dust to block out the sun.

這就是當時留下的隕石坑。

It wiped out 75 percent of all species on Earth.

十分的巨大。給你幾個具體的數據,

Now, not all asteroids are that big.

這裡的比例尺是

Some of them are smaller.

一格等於50英里, 兩個

Here is one that came in

100英里。那傢伙就有

over the United States in October of 1992.

300千米寬-- 即是200英里--

It came in on a Friday night.

一個巨大的坑

Why is that important?

把地球上一大塊土地砸了出來,

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

然後散開到全球, 並引起遍及世界範圍的火災,

and parents would bring them to their kids' football games

掀起的塵埃足以遮蓋天日。

to film their kids playing football.

還順帶毀滅了

And since this came in on a Friday,

地球上四分之三的物種。

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

但是, 並不是所有的天體都那麼大。

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

有些會小很多。

until it did that

我們這裡就會說道一個

to a car in New York.

在1992年10月

(Laughter)

抵達美國的這個小傢伙。

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

它在星期五下午入境。

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

但是爲什麽這是很重要呢?

about the size of a football,

因為當時攝影機

that hit that car and did that damage.

剛剛流行, 人們會隨身帶著它,

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

家長也會帶著它,

when it first came in.

爲了拍下他們的孩子在參加的

It broke up through atmospheric pressure,

足球比賽。那恰好隕石是在星期五到來,

it crumbled, and then the pieces fell apart

家長們就如此能把

and did some damage.

它是如何一遍粉碎一遍抵達美國的情形拍下來,

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

途徑西佛吉尼亞州, 馬里蘭州, 賓夕法尼亞州

because it would do that to it.

和新澤西州, 最終這樣

That would be bad.

跌在紐約的一輛汽車上。

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

（笑聲）

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

這不是一個200英里寬的坑,

to do a lot of damage.

但是你是可以在圖片的右邊

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

看到那隕石

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

有足球那般大的跌下,

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

造成導致那車的損壞。

that it is actually called "Meteor Crater."

那傢伙在剛進入地球時

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

估計有一輛校車那麼大。

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

在大氣的摩擦下它才

and those are recreational vehicles right there.

分解破散成小碎塊

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

然後造成一些毀壞。

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

同時, 你肯定也不會希望它打到你的腳

so roughly the size of Macky Auditorium here.

或你的頭, 因為這是可能的。

It came in at speeds that were tremendous,

那將會很糟糕。

slammed into the ground, blew up,

但它顯然不能毀掉地球上所有生命,

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

所以這還好。但是它同時警戒了我們,

a very hefty bomb.

我們並不需要6英里寬的石頭

This was 50,000 years ago,

就可以造成破壞。

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

在小隕石和大隕石件有一個

or something like that out in the desert,

中間值的傢伙,

but it probably would not have caused global devastation.

假如你們當中有人去過亞利桑那州溫士盧,

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

在那的沙漠裏面有一個隕石坑

to do a lot of damage.

非常具有代表性, 以至可稱為流星坑。

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

給點具體數據, 那坑應該有一英里寬。

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

假如從上往下看應該就是個停車場,

when he talked about the greatest cross-dimensional rift

在那邊停的就是幾輛旅遊車。

since the Siberia blast of 1909,

一英里寬, 六百英尺深。

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

造成這個坑的小行星估計有

(Laughter)

30到50碼寬,

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

大概就和麥基會堂差不多。

(Laughter)

它以極大的速度

Another rock came into the Earth's atmosphere

砸向地面, 並且爆炸,

and this one blew up above the ground,

威力大概和

several miles up above the surface of the Earth.

2000萬頓氫彈差不多--

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

重量級的大炸彈。

and then the shock wave came down and knocked down trees

那應該是在50000年前發生,

for hundreds of square miles.

當時可能毀滅了數隻水牛或羚羊,

This did a huge amount of damage.

或沙漠內這一類的的物種,

And again, this was a rock probably roughly the size

但是它肯定是沒有

of this auditorium that we're sitting in.

造成世界性的破壞。

In Meteor Crater, it was made of metal,

事實證明了小行星並不一定要

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

撞上了地球才會帶來很多災難。

The one over Tunguska was probably made of rock,

在1908年, 近西伯利亞

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

通古斯地區--你們當中有些人可能

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

是丹阿卡羅德迷很和看過〈捉鬼特工隊〉,

Now, when these things blow up,

在他的故事裡所描述到在1909

they're not going to do global ecological damage.

在西伯利亞巨大的次元裂縫, 就是我們要說的,

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

即使他把日期弄錯了, 但沒問題。（笑聲）

They're just not big enough.

那是1908年的事, 但我是無所謂的。

But they will do global economic damage,

（笑聲）

because they don't have to hit, necessarily,

又有一顆隕石造訪了地球,

to do this kind of damage.

但在離地球還有幾英里距離的

They don't have to do global devastation.

地方爆炸了。

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

爆炸所產生的熱量

it would cause a panic.

點燃了下面的森林, 衝擊波

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

震到了幾百平方米的

not that any city is more important than others,

樹, 厲害嗎？

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

這傢伙造成了不小的毀壞。

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

同樣的, 這石頭估計

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

也應該和我們的這所禮堂差不多大。

(Laughter)

不同的是, 流行坑的那個是鐵質的,

what can we do about this?

很牢固的綁在一起,

This is a potential threat.

所以才能撞到地面。

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

這個在通古斯的可能是

for 65 million years.

石質的有些鬆散

They're very rare.

所以在空中就爆炸了。

The smaller ones happen more often,

無論如何, 同樣的, 龐大的2000萬頓氫彈。

but probably on the order of a millennium,

當這些東西爆炸時,

every few centuries or every few thousand years.

它們不會造成全世界範圍的生態破壞。

But it's still something to be aware of.

不是像滅種恐龍

Well, what do we do about them?

那樣的大破壞。

The first thing we have to do is find them.

因為它們不夠大。

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

但是它們可能造成世界性的金融破壞,

It's right here.

因為它們並不用碰撞,

But you can see that it's extremely faint.

便能造成這種的毀壞。

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

它們不用造成全球性的破壞。

These are just stars.

因為不論那石頭落在了哪裡,

This is a rock that was about 30 yards across,

哪裡都會引起恐慌。

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

但是假若它撞向了一個重要的城市--

and hit Arizona 50,000 years ago.

不是說某一個城市比另一個重要,

These things are faint.

但是在全球經濟下

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

我們有某些比較需要的城市--

We have to find these things first.

作為一個文明社會我們肯定

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

會遭受巨大的毀壞。

NASA has devoted money to this;

好, 我已把你們嚇出尿來...

the National Science Foundation and other countries

(笑聲)

are interested in doing this.

但是我們面對這又能做些什麽呢?

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

這是一個潛在的危機。

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

我想強調的是我們已經有6500萬年

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

沒有遭到過像恐龍殺手那次一樣

What do we do?

巨大的破壞。因為這些例實在是太罕見。

You've probably heard about the asteroid Apophis.

許多規模較小的撞擊卻是經常發生的,

If you haven't yet, you will.

但是一般間隔

If you've heard about the Mayan 2012 apocalypse,

是不會超過幾個世紀或幾千年的,

you're going to hear about Apophis,

因此我們還是要關注它們。

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

但是我們又能做些什麽?

(Laughter)

首先當然是找到它們啦。

Apophis is an asteroid that was discovered in 2004.

這是在2009年經過美國的

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

小行星。

bigger than a football stadium.

就是這個。

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

你可以看到它十分微小。

And it's going to pass us so close

在這一連串的黑點,

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

說不定你們在後排看不到。看似像其他星星。

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

這石頭大概有30碼寬,

that if it's just right,

大概和在5萬年前通古斯和亞利桑那州

if it passes through this region of space,

爆炸的小行星差不多大。

this kidney-bean-shaped region called the keyhole,

小行星相對于巨大的天空很小。

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

所以我們要找到它們還是有難度的。

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

所以第一步要找到這些東西。

(Laughter)

呵呵, 好消息是我們已經找到它們。

you can't plan that kind of stuff --

NASA 在這方面投了相當的錢。

(Laughter)

國家自然科學基金委員會和其他國家

Apophis is going to hit us.

對這個項目都很感興趣。

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

爲了觀察這些危機我們

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

製造了一系列望遠鏡。這是非常偉大的第一步,

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

但是下一步又是什麽呢? 第二部

very, very low odds.

當然是在發現它們靠近我們時

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

把它們停下來。 如何做到呢?

I don't think Apophis is a problem.

你可能聽說過小行星

In fact, Apophis is a blessing in disguise,

阿婆菲斯。假如你沒聽過你肯定將會聽說到的。

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

假如你知道瑪雅的2012天啟,

This thing was discovered just a few years ago

你就肯定會知道阿婆菲斯,

and could hit us a few years from now.

因為你對世界末日的關鍵互聯網

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

有所關於。

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

阿婆菲斯是在2004年被發現的小行星。

and it turns out that's really important,

有250碼那麼寬,

because how do you stop an asteroid like this?

所以這夥計有點大--

Well, let me ask you:

和一個足球場差不多--

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

而且會在2029年四月經過地球。

What do you do?

並且會以很近的距離經過我們,

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

準確來說比天氣衛星

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

還要低一點。

but we can move a small asteroid.

地球的引力將會大大地彎曲它的

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

軌道, 倘若恰好,

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

便能穿過這個區域,

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

這個四季豆一樣形狀的

Comets are very much like asteroids.

叫做關鍵孔區域的地方, 那麼地球的引力

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

就能足夠彎曲它的軌道, 然後再7年後的

the purpose was to make a crater to excavate the material

四月13日, 星期五, 不得不提,

and see what was underneath the surface of this comet,

是2036年... (笑聲)

which we learned quite a bit about.

-- 這不是巧合哦（黑色星期五）--

We did move the comet a little tiny bit --

阿婆菲斯將會撞擊到地球。

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

並且那250碼的身姿

However, think about this:

肯定會造成不小的傷害。

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

但是有好消息的是它穿過

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

這個關鍵區域的可能性

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

和在下一次回歸時撞上我們的幾率是

That means we can do it again.

100萬分之一, 很小很小的幾率,

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

所以我個人是肯定不會爲了擔心它而睡不著覺。

and we have two years to go?

我認為阿婆菲斯的存在對我們並不壞。

Boom! We hit it.

而是一個變相的好事,

You know, if you watch the movies --

它讓我們察覺到了

(Laughter)

原來還有這樣的危機存在。

you might think:

它僅僅是在幾年前被發現,

Why don't we use a nuclear weapon?

然後有可能在幾年後撞上我們。

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

但是它不會, 而且讓我們得到了

Shoot a nuclear weapon at this thing,

一個去學習這些小行星的機會。我們之前

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

是並沒有去研究這些關鍵孔的,

or else you'll miss it.

但是我們現在明白, 並且知道了

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