stayscience fictionLi,The fate of the earthIt’s terrible, not byBlack hole phagocytosis, is byAsteroid Impacts 。

Although I know it isliterary works, but my heart is still for the earthPinched a sweat。

But astronomers say these areMay happenYes, for example现stay, there is only oneRed dwarfstay向我们靠近。

Astronomers believe that it will entersolar systemarriveOort cloud , upsetOriginal system, bringing a series of changes.

This isWhich oneRed dwarf？它会对earth造成什么influence？ What should we doanswer？ Astronomers mentionedOort cloud Where is it?

让我们深入宇宙，看看这颗快速奔向solar system的Red dwarf，现stay留给我们的时间，还有1.5 million years！

This isWhich oneRed dwarf？

First of all, let’s meetRed dwarf, it isfixed starA kind of,qualityNot more than the sunhalf，volumeMaybeSmallerYes.

At the same time, it is also in the universeThe largest number的fixed star，占据fixed star总量的70%。

Red dwarf的Very low brightness, some evenInvisible to the naked eyeYes, we must rely onAstronomical telescope。

也就是说我们看到的漫天星空中，几乎没有Red dwarf的figure。

This is因为Red dwarfvolume太小So the abovehydrogen atomFusion intensity完全比不上太阳这样的fixed star, it的表面温度也只有2500-5000K。

不过这样也有一个好处，Red dwarf的lifeExtremely long, can achieveTens of billions of years。

最老的Red dwarf可能Same age as the universe。

这颗奔向solar system的Red dwarf叫做Gliese710, located inSerpent，quality约为太阳的half，距离solar system约63 light years。

根据天文学家的观察, it正stay做Self motion, speed per second3.4 km。

为何一颗fixed star会朝着另一颗fixed starFlying?

这就不得不提到，我们对于fixed star有一个misunderstanding，那就是fixed star也是会revolutionof太阳等fixed star正stay围绕the galaxycore的一个天体revolution，速度achieve了每秒220 kmFor a period of up to250million years。

stay这个过程中，一些小型fixed star会出现“Lost”Phenomenon of. That is, by其他大型fixed stargravitation的influence，偏离了自己的revolution轨道。

Gliese710 is such a oneget lost的Red dwarf，stay不知道经历了什么gravitationBack, towardssolar systemCome at a gallop.

现stay它距离solar system还比较远，因此奔来的Not fast，等它越来越靠近solar system之后，就会stay太阳的gravitationlowerAccelerate approach。

一个太阳half大的fixed star奔向solar system，我们最关心的就是, it会不会And the earthCollision？ On this point, we candon ‘t worry, ititself不会And the earthCollision。

但是，stay它的influencelower，Other celestial bodies会不会撞上earth，那就不是我们说了算of

它会对earth造成什么influence？

这颗Red dwarfGliese710stay进入solar system后，会stayOort cloud Stay for a while.

Oort cloud 是天文学家们假设认为的solar systemboundary, there iscometHometown of, there are many moreUnknown celestial body。

Gliese710的quality对于太阳来说Very small，可是对于solar system的Other celestial bodiesFor example,Particularly large，足以stayOort cloud 内Make waves。

首先就是, it会改变Oort cloud 的structureThat originally surrounded the suncomet轨道Change, one part will run around it, and the other part will rush toplanets。

届时，八个行星都免不了lower一场“comet雨”。

It doesn’t matter to other planets, but it doesearth来说就难Yes.

1994，一颗comet撞击了Jupiter, resulting in impact crater diameterTens of thousands of kilometers, if it wasearth，earth将面临一场Catastrophe。

这还只是一颗comet，而Gliese710What caused is“comet雨”，撞向earth的comet是One after another, in groupsof

On that day, maybe human beings will understanddinosaur当年的处境Yes.

comet的主要成分不是岩石，而是Solid water, solidmethane等, it们arriveearth后会melt, changeearth的水量and大气中的methane含量。

methane是一种Flammable gas，被撞击后的earth会陷入Sea of fire, you can see beautiful pictures every day“Fireworks”。

methane燃烧会消耗earth的oxygen, increasecarbon dioxide的含量，earth很有可能一夜之间Burned into Venus。

到时候的earth上全是carbon dioxide, it们会让earth陷入严重的greenhouse effect。

天文学家们推测，这场comet撞击，很有可能会摧毁earth长久以来的oxygen系统，让earth再次回到Anaerobic or hypoxic的时代，earth的生命可能不会It’s over, may return onceBefore evolution, once again reduced toLower organismForm of.

as forhuman beings，作为食物链顶端的物种，会成为earth版本更newvictim。

也就是说，当Gliese710进入solar system之后，一切都会Change occurs，solar systemWill alsoReshuffle cards。

Gliese710有可能stayOort cloud 建立一个Own system, absorbing nebula and Kuiper Belt objects to itsgravitation范围, become anewfixed star系。

这样它就会and太阳展开Fierce competitionTo compete for celestial bodies“Fight openly and secretly”。

When the competition reaches about 5billion years, the sun has finished its ownMain sequence star, startexpand, devour the nearest to itself4 planets。

而Red dwarfGliese710的lifeFar more than the sun, and finally the sun will be alive“Boil to death”。

The burning sun turned intoWhite dwarf，Red dwarf还是那个Red dwarf, butsolar system不存stay了，只剩lower了属于Galaxy of gliese710。

那么我们human beings就真的没有办法deal withGliese710Is it?

human beings应该怎样answer？

according toGliese710现stay的Speed and distance, it进入solar systemOort cloud 的时间还有大约1.5 million years，human beings如果那个时候还没有Extinction, should have enteredHigher civilizationYes.

according tohuman beings目前的Development speed, reachFirst class civilizationAbout100 to 200 years。

achieveFour levels of civilization的human beings，拥有了Interstellar shuttleAbility to goEvery corner of the universe。

这个时候的solar system就不是我们The only home，可能human beings都不staysolar systemYes.

So what happened has无法influence到human beings，我们会stay宇宙的Another corner观看earth的“Fireworks”。

Gliese710对于现stay的human beings来说是InvincibleYes, but for1.5 million years后的human beingsFor example,一切还是unknown number。

它的到来对于earthFor example,实stay是Too far awayYes!

But astronomers have repeatedly mentionedOort cloud It has attracted everyone’s attention. What is thisWhat zone, why is there no information about it at presentdataAnd?

Oort cloud Where is it?

Oort cloud 是天文学家们假想的一个Spherical cloud shaped object, covering the wholesolar system，是solar system的boundary。

之所以没有它更多的data，是因为我们的detector, has not yet entered the setNebula space。

目前飞得最远的两个detector，Voyager oneand二号, just exploredKuiper belt，飞越了狭义上的solar system。

想要真正离开solar system，就必须飞越Oort cloud 。

算上Oort cloud ，solar system的直径可能有大约4 light years。

Oort cloud 最厚的地方可能有1 light year, Voyager 1 needs about300 years的时间才能arrive，而穿越它需要越30000 years。

天文学家们推测，Oort cloud 是当初solar systemResidue after birth，被遗落stayOutermost layer，包裹着solar system，同时也为solar system提供着protect。

Oort cloud 中存stay很多天体, because it’s far from the sunToo far。 Most of them areSolid water, organic matterOf which the most well-known iscometYes.

Oort cloud 还有可能是earth上的水Hometown of。

有一种假说就是，earth的水是comet撞击带来的，甚至这些comet还携带着earth最初的生命。

如果这个假说成立，那么Oort cloud 里可能存stay生命, butToo cold了, it们处于Sleep state。

The arrival of gliese710 will bringquantity of heat, maybe there will beset up a separate kitchen, formingnew生命。

What will happen in the future? It’s still aunknown number，Red dwarf的到来也无法阻止我们The pace of exploring the universe。