我们能在太阳的死亡中幸存下来吗？：英语精读讲义

The Sun is around 4.5 billion years old

太阳大约有45亿岁了

and just like you and I, 短語搭配

它和你我一样，

it's aging.

也在逐渐衰老。

In just over a billion years,

再过十亿多年，

the Sun will have expanded so much 語法

太阳将膨胀到如此之大，

that the heat will begin to melt

其热量将开始熔化

the Earth's surface.

地球表面。

So,

那么，

is there any way 語法

有没有什么办法

us Earthlings can avoid

能让我们地球人躲过

this detrimental event?

这场灾难呢？

Can we save ourselves 短語搭配

我们能拯救自己，

from the Sun's ultimate death?

逃过太阳最终的死亡吗？

Sure,

当然，

none of us will be here,

我们谁也活不到那时候，

assuming we don't find the secret 語法

除非我们能找到

to everlasting life,

永生的秘密，

but at the billion year mark, 短語搭配

但到十亿年这个节点，

the Sun will have used up 短語動詞

太阳将耗尽

the hydrogen fuel in its core,

其核心中的氢燃料，

forcing it to burn at its surface. 語法

迫使它转而在表面燃烧。

The increased radiation will boil away 短語動詞

增强的辐射会蒸干

all of the water on Earth,

地球上的所有水，

creating an international desert.

让整个世界变成一片沙漠。

Flash forward about 5 billion years 表達脈絡

再快进大约50亿年，

and the swelling Sun will begin

不断膨胀的太阳将开始

literally melting mountains

真正把群山熔化，

with most, if not all life on Earth, 短語搭配

届时，地球上的生命即使没有全部，

now extinct.

也已大多灭绝。

Around 7.5 billion years,

大约75亿年后，

the expanding Sun,

持续膨胀的太阳

now a red giant, 文化背景

此时已成为一颗红巨星，

will engulf the Earth entirely.

会将地球彻底吞没。

Sounds bleak. 語氣意圖

听起来前景惨淡。

So, can we avoid this hot mess? 習語

那么，我们能躲过这场炽热浩劫吗？

It turns out our best bet 講解

事实证明，我们最有希望的办法

lies in something called gravity assist,

在于一种叫作“引力助推”的技术，

a technique we've been using for years 語法

多年来我们一直在使用它，

only to launch spacecrafts

但仅用于发射航天器，

throughout our solar system.

让它们穿行于太阳系。

Anytime a spacecraft or satellite

每当航天器或卫星

comes in close proximity to a planet, 短語搭配

靠近一颗行星时，

gravity grabs hold. 習語

引力就会将它抓住。

And if the spacecraft arrives

如果航天器

at the perfect angle,

以恰到好处的角度接近，

it's able to use some

它就能借用

of the planet's velocity

这颗行星的一部分速度，

to catapult it further into space. 用詞

将自己弹射到更远的太空。

This extra energy comes

这部分额外能量

from the planet's own energy of motion

来自行星自身

around the Sun.

绕太阳运行的动能。

But as Newton famously said,

但正如牛顿的名言：

to every action, 文化背景

每一个作用力，

there is an equal and opposite reaction.

都有一个大小相等、方向相反的反作用力。

As the spacecraft uses

当航天器利用

the Earth's gravity to speed

地球引力加速

up and move towards Earth,

并飞向地球时，

the planet will ever so slightly slow down 短語搭配

地球也会极其轻微地减速，

and move towards the spacecraft.

并朝航天器移动。

Of course,

当然，

the spacecraft's mass is so small

相比之下，航天器的质量太小，

comparatively that it gets launched

所以它会被弹射出去

incredibly far

极其遥远的距离，

while the planet experiences little change.

而行星几乎不会发生变化。

But if we were to increase 語法

但如果我们增大

the spacecraft's size or use an asteroid,

航天器的尺寸，或改用一颗小行星，

we could potentially move

就有可能把

the Earth's orbit away from the Sun.

地球轨道推得离太阳更远。

This would take millions of years

这需要数百万年，

and involve large objects

还得让大型天体

coming just close enough 語法

以刚刚好的距离靠近，

to not collide with Earth.

又不至于撞上地球。

But hey,

不过，

we've got a billion year head start. 習語

我们可是有十亿年的准备时间。

It may seem far fetched, 用詞

这听起来也许很不切实际，

but it's already happening.

但这种事已经在发生了。

On October 9th, 2013,

2013年10月9日，

Earth will be used to gravity assist 文化背景

地球将通过引力助推

a spacecraft called Juno,

一艘名为“朱诺号”的航天器，

which is on its way to Jupiter. 短語搭配

它正飞往木星。

As Juno flies within 559 km of us,

当“朱诺号”飞到距地球不到559千米处时，

it will use Earth's gravity as a slingshot 習語

它会把地球引力当作弹弓，

to boost its velocity 短語搭配

将自身速度提高

by 7.3 km per second.

每秒7.3千米。

Meanwhile,

与此同时，

Earth will have been moved by a fraction. 語法

地球也会发生极其微小的位移。

Juno will later arrive at Jupiter in 2016,

之后，“朱诺号”将于2016年抵达木星，

where it will study

在那里研究

the interior of the planet

这颗行星的内部，

and help to unveil

并帮助揭开

many new spectacular mysteries

许多全新而惊人的谜团。

of our solar system.

这些谜团就隐藏在我们的太阳系中。

In order to move the Earth 語法

为了移动地球，

within our billion year timeline,

并把时间控制在十亿年内，

we would need approximately one encounter 語法

我们大约需要进行一次交会，

every 6,000 years

频率为每6000年一次，

using an object with a mass

所用天体的质量

of approximately 10 to the 19 kg. 用詞

约为10的19次方千克。

That's 19 zeros,

也就是1后面有19个零，

somewhere around the size 短語搭配

大小大致相当于

of a 100 km wide asteroid.

一颗宽100千米的小行星。

In between passes,

每两次交会之间，

the asteroid would slingshot around the Sun,

这颗小行星会借太阳进行引力弹射，

fly out to Jupiter,

飞向木星，

and then be gravity assisted back to Earth,

再借助引力返回地球，

like one long version 表達脈絡

就像一场超长版的

of catch between planets.

行星间抛接球。

Over millions of years,

数百万年下来，

this would move the Earth

这会把地球移到

to a comfortable 225 million km orbit

一条舒适的2.25亿千米轨道上，

out from the Sun.

远离太阳。

And while it is feasible, 語法

尽管这个方案可行，

even with today's technology,

甚至用今天的技术就能做到，

it doesn't come without risks. 短語搭配

但它并非没有风险。

For one, 表達脈絡

首先，

we may lose the Moon,

我们可能会失去月球，

which could ultimately create

最终可能由此引发

some extreme weather patterns.

一些极端天气模式。

Not to mention, 表達脈絡

更别提，

the Earth's spin may increase,

地球的自转可能会加快，

making days only hours long. 語法

让一天只剩几个小时。

The surrounding planets,

周围的行星，

like our new neighbor Mars,

比如我们的新邻居火星，

would likely have their own orbits destabilized. 語法

其自身轨道也很可能变得不稳定。

And,

而且，

you know, 語氣意圖

你懂的，

the asteroid could come plummeting 短語搭配

小行星还可能意外地

into Earth by accident.

一头撞向地球。

But perhaps these are the risks 表達脈絡

但或许，这些正是

we need to take

我们必须承担的风险，

to give our descendants, the planet,

好让我们的后代、这颗星球

and all life on it

以及星球上的所有生命

a few extra billion years.

多拥有几十亿年的时光。

Got a burning question you want answered? 習語

有迫切想知道答案的问题吗？

Ask it in the comments

请在评论区提问，

or on Facebook and Twitter.

或到Facebook和Twitter上告诉我们。

And if you want to learn more about Juno,

如果你想进一步了解“朱诺号”，

check out its awesome interactive website

不妨看看它超棒的互动网站，

we've linked in the description.

链接就在视频简介中。

Special thanks to NASA

特别感谢NASA

for inspiring and supporting this episode.

为本期视频带来灵感并提供支持。

And subscribe

别忘了订阅，

for more weekly science videos.

每周观看更多科学视频。