宇宙（2007）

So far,
目前为止
our journey through the seven wonders
我们已经领略了太阳系
of the Solar System has taken us
七大奇观之中的
to the geysers of Enceladus,
土卫二间歇冰泉
the Rings of Saturn
土星环
and the Great Red Spot on Jupiter.
以及木星大红斑
Now, we continue to travel through the fourth of our wonders,
现在 我们继续探索太阳系第四大奇观
the Asteroid Belt.
小行星带
This band of leftover debris has even made it to the big screen,
这些远古遗物曾被搬上大银幕
and the rocks Hollywood is obsessed with the most
最令好莱坞着迷的
are those that escape the Asteroid Belt
是那些脱离小行星带
and head for planet Earth.
撞击地球的天外陨石
Near-Earth Objects or NEOs
近地天体是指
are cosmic rocks like asteroids or comets,
几乎每天都光临地球的
which strike Earth almost every day.
外太空岩石 例如小行星或者彗星
We're really very interested in Near-Earth Objects,
我们确实对近地天体很感兴趣
objects that pass across the orbit of the Earth around the sun
关注那些穿过地球公转轨道的天体
because occasionally they can and do collide with the Earth,
因为它们撞击地球的几率非常大
and if they're big enough they can cause vast destruction here on Earth.
如果足够大 则可能对地球造成大面♥积♥破坏
On April 14, 2010,
2010年4月14日
cameras caught sight of a 3-foot fiery asteroid
有镜头捕捉到一直径三英尺的小行星
streaming over the Midwestern United States.
从美国中西部天空呼啸划过
Fortunately, the cosmic rock broke into tiny pieces
幸运的是 在它撞到地面前
before hitting the ground.
就已碎裂成小块
But in the past,
但在过去
large asteroid impacts have created gigantic craters,
小行星撞击曾形成巨大陨坑
and even triggered mass extinction events
甚至导致了大规模物种灭绝
like the Chicxulub asteroid that killed off the dinosaurs.
比如导致恐龙灭绝的希克苏鲁伯小行星
Over the last billions of years,
在过去的十多亿年中
Earth has been hit many times by asteroids of various sizes.
地球被大小不一的小行星撞击过无数次
The impact that occurred roughly 65 million years ago
大约6.5亿年前
that perhaps wiped out the dinosaurs
一颗直径大约大约六英里的的小行星
was an example of something that was about six miles across
撞向了今日墨西哥的区域
that slammed into, what is now Mexico,
促使恐龙灭亡
and caused huge global ramifications for the Earth.
对全球造成了难以想象的影响
A number of new space surveys are currently tracking
目前 一系列最新太空研究
all Near-Earth Objects
正在追踪
that are large enough to destroy a modern city,
所有足以摧毁一座现代城市的近地天体
or even worse, ignite a global catastrophe.
其中一些甚至会导致全球性大灾难
We know of most of the objects that are larger than a mile
我们已经追踪了所有直径超过一英里
that can intersect the Earth's orbit,
而且运行轨道可能与地球相交的天体
and so the effort now is going in to
现在的目标是
finding these sort of stadium-sized objects,
定位那些体育场大小的天体
that while not completely devastating to the entire Earth,
虽然不足以毁灭地球
would be a huge deal if they hit the Earth.
但仍会对地球造成巨大影响
As we leave behind the Asteroid Belt,
我们将小行星带留在身后
we chart a course to the next of our seven wonders,
驶向七大奇迹的下一站
number three...
第三奇观
Olympus Mons.
火星奥林帕斯山
the largest volcano in the Solar System.
太阳系中最大的火山
As we approach the planet mars,
离火星越来越近
we immediately catch sight of this mammoth mountain.
这座硕大无朋的山体立刻吸引了我们的注意
The base of it is about almost 350 miles across,
山体底部直径大约350英里
that's, as though, the base of the mountain
这段距离相当于
were from Los Angeles to San Francisco.
从洛杉矶到旧金山
So even though it's so high,
所以虽然海拔很高
the slope is very gradual.
但是坡度很平缓
You would barely know you were climbing a mountain.
你几乎无法察觉自己在爬山
It's not like a steep volcano,
它不是陡峭的火山
It's just... It's a smooth, low slope,
坡度很平缓
but it just goes on forever.
但是仿佛没有尽头
Olympus Mons is located in the Tharsis Bulge,
奥林帕斯山位于塔尔西斯高地
a region on the red planet that's home to other massive volcanoes.
在那一地区还许多其他大型火山
If you climb the 13 miles to its summit,
如果你爬上13英里高的山顶
you could take in a view of the very edge of the Martian atmosphere.
你可以看到火星大气的边缘
Olympus Mons is several times higher than the highest mountains on Earth,
奥林帕斯山比地球最高峰高出许多倍
and its base is hundreds of miles across.
而山体底部更是方圆几百英里
And it's been formed over the last billions of years
在过去的数十亿年间
by eruption after eruption after eruption,
经过一次又一次的火山喷发
which has slowly surfaced it with successive layers of lava.
由无数层的岩浆堆积而成
100 million years ago, hot lava rivers poured down from its peak
一亿年前 滚烫的岩浆从山顶喷涌而出
to cover millions of square miles of the red planet.
覆盖了几百万平方英里的火星地表
Today Olympus Mons is 100 times
坐落于夏威夷岛的莫纳罗亚山
the volume of Earth's largest volcano, Mauna Loa,
是地球上最大的火山
located on the big island of Hawaii.
如今的奥林帕斯山体积是它的100倍
Olympus Mons got so much larger than anything here,
奥林帕斯山比地球上的一切都大许多
for, well, a number of reasons.
原因有许多
One is certainly, there was just a lot of volcanic activity.
有一点是肯定的 那里有很多的火山运动
A second is that mare's gravity is much lower.
其二则是那里的重力小很多
You weigh a lot less on mars.
你在火星上的体重会轻许多
So as the mountain built up, it didn't compact back down.
所以随着山体的增高 它不会塌方
It was able to build up to a pretty huge volcano without collapsing.
火山可以堆积得很高而不崩塌
The third and perhaps most important reason
第三点
why Olympus Mons is so huge
也许是其如此巨大最重要的原因
is that mars doesn't have plate tectonics,
火星上没有板块构造
the movement of crustal plates
不像地球
that rest on top of the molten interior of bodies, such as Earth.
熔融状地幔上方的地壳会发生运动
Olympus Mons grew to such a big size
奥林帕斯山体积可以增长到如此巨大
because of the lack of tectonic motions on mars.
因为火星上没有板块运动
The hot spot from which the lava, the magma, emerged
岩浆喷涌而出的地点
remained at one location,
始终不变
allowing more and more material to build up
这就可以堆积起越来越大山体
and create a super mountain, a super volcano.
形成一座超级火山
Mars is now presumed to be geologically inactive.
火星现在被认为处于地质不活跃期
But is the volcanic beast really dead
但是那火山猛兽是真的已死
or merely a sleeping giant?
抑或仅仅还在休眠
The European Space Agency's Mars Express Mission recently captured
欧洲航♥天♥局的火星快车号♥日前捕捉到了
the highest resolution images ever taken of the planet's lava flows.
有史以来分辨率最高的岩浆流图象
Some flows date back 115 million years,
有些可以追溯到一亿多年前
but others are only 2 million years old,
但还有一些仅有200万年历史
and on geologic time scales that's very recent,
以地质时间刻度来看那是很短的时间
which suggests there still may be some volcanic activity.
也就意味着现在也许还有火山喷发
If we look at the surface of Olympus Mons,
如果看看奥林帕斯山表面
we see especially that there are lava flows,
我们能看到有一些岩浆流之上
which have very few craters on them.
几乎没有陨石坑
And so, we know that those lava flows are
于是我们知道 这些岩浆流
perhaps 10s-20 million years old at the oldest.
最老也不错一两千万年
But the eruptive activity has been going on
但是喷发运动一直在继续
until the relatively recent past,
如果不是一直延续到了今天
if not right up until the present day.
那也是不久之前才停止的
Olympus Mons may have once produced vast amounts of lava,
奥林帕斯山也许曾经产生过大量的岩浆
but its hellish heat paled in comparison
但那地狱烈焰般的热度
to the current temperatures
与我们太阳系七大奇观
of number two on our countdown
榜上第二名相比
of the seven incredible wonders of our Solar System.
则是小巫见大巫了
This may look like a ball of flames.
它远看像是个大火球
But its surface is an ocean
其表面是温度高达一万度
Of 10,000-degree plasma
等离子海洋
with waves, winds
伴随着大风巨浪
and massive eruptions
以及大规模喷发
as explosive as a billion tons of TNT.
堪比十亿吨♥TNT炸♥药♥同时爆♥炸♥
Our next wonder of the Solar System
下一个将要探究的太阳系奇观
has been Earth's best friend and foe.
既是地球的朋友 又是最大敌人
It's bathed our planet with heat and energy,
它用光和热笼罩着我们的星球
But it's also blasted us with potentially deadly
但其释放的致命高能粒子波
highly energetic particles and waves.
也会伤害到我们
We now navigate around number two:
我们继续探索第二奇观
the sizzling surface of the sun.
极热的太阳表面
The surface of the sun is really quite chaotic.
太阳表面相当杂乱无序
It's always boiling and bubbling.
它持续沸腾 不断冒泡