百科知識視頻之煎蛋小學堂45 世界末日，人類如何自保？

The sun is around 4.5 billion years old.And just like you and I,it's aging,In just over a billion years,the sun will expand it so much that the heat will begin to melt the earth's surface,So,is there any way as earth things can avoid this detrimental event?Can we save ourselves from the sun's ultimate death?

太陽已有大約45億歲了。正如你我一樣 它也在衰老。在10億年后 它將變得巨大 它帶來的熱量會融化地球表面。地球生物怎么才能躲過這次致命的打擊?在太陽消亡時我們能否自保?

Sure,none of us would be here,assuming we don't find the secret to everlasting life.but at the billion year mark,the sun will have used up the hydrogen fuel in its core,forcing it to burn at its surface.The increase radiation will boil away all of the water on earth,creating an international desert.

當然 如果沒發(fā)現(xiàn)長生不老的秘訣 我們活不到那時候。但十億年后 太陽將會耗盡其內(nèi)核所有的氫燃料，迫使其在表面燃燒。不斷增強的輻射會蒸發(fā)干地球上所有的水分，造出洲際沙漠。

Flash foward about 5 billion years,and the swelling sun will bigin literally melting mountains with most,if not all life on earth,now extinct.Around 7.5 billion years,the expanding sun,now a red giant,will engulf the earth entirely,Sounds bleak,so can we avoid this hot mass?

再向后50億年 巨大的太陽開始將融化山脈 而地球上絕大多數(shù)生物早已滅絕。75億年后 不斷膨脹的太陽已成紅巨星，并將完全吞噬地球。聽起來很嚇人 那我們能躲過這團熱球嗎?

It turns out,our best bet lies something called gravity assist.a technique we have been using for years only to launch space craft through our solar system.Any time a space craft or satellite comes in close proximity to a planet,Cravity grabs hold.And if the spacecraft arrives at the perfect angle,it's able to use some of the planet velocity to catapult it further into space.This extra energy comes from the planet's own enery of motion around the sun.

實際上 我們最有利的賭注在于引力助推。一種多年來 我們只用在向太陽系內(nèi)發(fā)射航天器的技術(shù)。當飛行器或衛(wèi)星靠近行星時，重力會抓住它。如果飛行器的角度剛好合適，它可以利用行星的速度將自身推到宇宙更遠。多余的能量來自于行星繞太陽旋轉(zhuǎn)時自身的動能。

But as Newton famously said,To every action,there's an equal and opposite reaction.As the spacecraft uses the earth's gravity to speed up and move towards the earth,the planet will ever so slighty slow down and move toward the spacecraft.Of course,the spacecraft's mass is so small comparatively that it gets launched incredibly far while the planet experience little change.

但正如牛頓所言 每個作用力都存在與之大小相等 方向相反的反作用力。當飛行器利用地球引力加速 向地球靠近時，地球的速度會略有下降 并向飛行器靠近一點。當然 相比之下飛行器的質(zhì)量太小 以至于衛(wèi)星可被發(fā)射到極遠處 而行星卻絲毫未變。

But,if we were to increase the spacecraft's size,or use an asteroid,we could potentially move the earth's orbit away from the sun.This would take millions of years and involve large objects coming just close enough to not collide with earth.But,hey,we're got a billions years ahead start.It may seem far fetched,but it's already happening.

但是 如果能讓飛行器變大 或者利用小行星，我們就可以讓地球軌道遠離太陽。這需要數(shù)百萬年時間，并得讓足夠大的物體離地球夠近 卻不能撞到地球。但是 我們還有好幾十億年時間呢。看上去很遙遠 但這已經(jīng)在發(fā)生了。

On Oct,9,2013,earth will be used up to gravity assist a spacecraft called Juno which is on its way to Jupiter,As Juno flies within 559 km of us,it will use earth's gravity as the slingshot to boost its velocity by 7.3km/s.Meanwhile,earth will have been moved by a fraction.Juno will later arrive at Jupiter in 2016,where it will study the interior of the planet and help to unveil many new spectacular mysteries of our solar system.

在2013年10月9日 地球?qū)橐活w名叫“Juno"的航天器做引力助推 后者正向木星前進。當Juno飛到距我們559千米處時，地球引力將是它的彈力 它將借此加速到7.3km/s。與此同時 地球僅被移動了一點點。Juno將在2016年抵達木星。在那里 它會研究行星的內(nèi)部 并幫助我們揭秘關(guān)于太陽系的諸多精彩謎題。

In order to move the earth within our billion year's time line,we would need approximately one encounter every 6000 years,using an object with a mass of approximately 10^19 kilograms.That's 0000,0000,0000,0000,000.Some are around the size of 100 kilometer wide asteroids,In between passes,the asteroid would slingshot around the sun,fly up to Jupiter and be gravity assisted back to the earth.Like one long version of catch between planets.

為了在這十億年間移動地球，我們大約得每6000年一次 用一個質(zhì)量大約為10^19千克的物體。就是0000，0000，0000，0000，000.某些直徑100千米的小行星差不多的東西。在中間穿過時 小行星繞太陽繞太陽加速，飛到火星 之后又被引力助推回地球。正如長距版的星際拋球。

Over millions of years,this would move the earth to a comfortable 225 million km orbit out from the sun.While it is feasible,even with today's technology,it doesn't come without risks.For one,we may lose the moon,which could ultimately create some extreme weather patterns.Not to mention,the earth's spin may increase,making days only hours long,The surrounding planets like our new neighbors,Mars,would likely have their own orbits disstabilized.

幾百萬年后 地球?qū)⒁虼硕苿拥桨踩嚯x 距太陽 2.25億公里的軌道。而即使計劃可行 憑借今天的科技 這種方式仍有風險。其一 我們會失去月亮。這終將導致某些極端天氣模式。更不用說地球自轉(zhuǎn)的速度也將加快 每天都只有幾小時。我們周圍的新鄰居 如火星，他們的軌道會變的不穩(wěn)定。

You know,the asteroid could come plummeting into earth by accident.But perhaps these other risks we need to take to give our decedents,the planet,and all life on it,a few extra billions of years.

你知道 小行星也會偶然間砸向地球表面。不過 我們可能得把這些風險留給我們的子孫了 一顆行星 其上所有的生命 還有幾十億年。