首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
How many things can you see in the night sky? A lot! On a clear night you might see the Moon, some planets,and thousands of spar
How many things can you see in the night sky? A lot! On a clear night you might see the Moon, some planets,and thousands of spar
admin
2013-01-29
87
问题
How many things can you see in the night sky? A lot! On a clear night you might see the Moon, some planets,and thousands of sparkling stars.
You can see even more with a telescope. You might see stars where before you only saw dark space. You might see that many stars look larger than others. You might see that some stars that look white are really red or blue. With bigger and bigger telescopes you can see more and more objects in the sky. And you can see those objects in more and more details.
But scientists believe there are some things in the sky that we will never see. We won’t see them with the biggest telescope in the world, on the clearest night of the year. That’s because they’re invisible. They’re the mysterious dead stars called black holes.
You might find it hard to imagine that stars die. After all,our Sun is a star. Year after year we see it up in the sky burning brightly,giving us heat and light. The Sun certainly doesn’t seem to be getting old or weak. But stars do burn out and die after billions of years.
As a star’s gases burn,they give off light and heat. But when the gas runs out,the star stops burning and begins to die.
As the star cools,the outer layers of the star pull in toward the center. The star squashes into a smaller and smaller ball. If the star was very small, the star ends up as a cold, dark ball called a black dwarf. If the star was very big, it keeps squashing inward until it’s packed together tighter than anything in the universe.
Imagine if the each were crushed until it was the size of a tiny marble. That’s how tightly this dead star, a black hole is packed. What pulls the star in toward its center with such power? It’s the same force that pulls you down when you jump—the force called gravity. A black hole is so tightly packed that its gravity sucks in everything—even light. The light from black hole can never come back to your eyes. That’s why you see nothing but blackness.
So the next time you stare up at the night sky,remember: there’s more in the sky than meets the eyes! Scattered in the silent darkness are black holes—the great mystery of space.
Why can’t you see light when you look at a black hole?
选项
A、Because most black holes are so far away.
B、Because the gravity of a black hole is so strong that it sucks the light inward.
C、Because as the star’s gases burn, it stops giving off heat and light.
D、Because as a star cools, its outer layers pull in toward its center.
答案
B
解析
题目问:当你看到一个黑洞时,为什么你不能见到光?倒数第二段“A black hole is so tightly packed that its gravity sucks in everything——even light.The light from black hole Can never come back to your eyes.That’s why you see noting but blackness.”通过这段话可知,黑洞是如此的紧凑,以至于它的重力吸收一切东西。甚至是光。黑洞里的光永远也到不了你的眼睛里。这就是你为什么看到一片漆黑的原因。所以,答案是A。
转载请注明原文地址:https://kaotiyun.com/show/Q01O777K
0
考博英语
相关试题推荐
Mostpeoplewhotravellongdistancecomplainofjetlag.Jetlagmakesbusinesstravelerslessproductiveandmoreprone【21】makin
Mostpeoplewhotravellongdistancecomplainofjetlag.Jetlagmakesbusinesstravelerslessproductiveandmoreprone【21】makin
Mostpeoplewhotravellongdistancecomplainofjetlag.Jetlagmakesbusinesstravelerslessproductiveandmoreprone【21】makin
Throughouthistorymanhashadtoacceptthefactthatalllivingthingsmustdie,butpeoplenowlivelongerthanthey【51】Yet,
Today,ahigh-levelfinancemanagerisjustaslikelytobeacasual-looking21-year-oldasabaldingexecutive.Theyhavealle
Punditswhowanttosoundjudiciousarefondofwarmingagainstgeneralizing.Eachcountryisdifferent,theysay,andnoonest
ThementalhealthmovementintheUnitedStatesbeganwithaperiodofconsiderableenlightenment.DorotheaDixwasshockedtof
Thereare______differencesbetweentheoryandpractice.
Punditswhowanttosoundjudiciousarefondofwarningagainstgeneralizing.Eachcountryisdifferent,theysay,andnoonest
Recentlysome______incidentsinvolvingmistreatmentofnewimmigrantsandethnicgroupshaveoccurredinsomeEuropeancountries
随机试题
A.腹会阴联合直肠癌根治术B.经腹腔直肠癌切除术C.经腹腔直肠癌切除、近端造口、远端封闭手术D.乙状结肠造口术直肠癌块下缘距肛门10cm的患者,原则上适用
用硫酸镁缓解子痫惊厥时,给药途径应当是
正常分娩胎膜破裂的时间一般是在
企业采用购买通用会计软件方式配备会计软件时,软件安全保密性强,用户只能执行软件功能,不能访问和修改源程序。()
乙公司是一家上市公司,适用的企业所得税税率为25%,该公司要求的最低报酬率为10%。目前甲公司面临A、B两个投资方案的决策。资料如下:资料一:A、B两个方案有关投资的数据资料如下表所示:假设两个方案原始投资均是在0时点一次性投入,立即投产经营,均采用
关于注册会计师接受委托前的沟通,下列说法中正确的是()。
回忆材料的中间部分识记效果较差,其原因可能有()
下列不属于我国国家主席职权的是()。
HermanMelvillecalledhisfriendNathanielHawthorne______inAmericanLiterature.
A、TheUnitedStates.B、Iran.C、TheUnitedArabEmirates.D、Notmentioned.D推理题。eyshlisteninga结尾处说到,伊朗责怪是美国埋了地雷,可BBC驻该地区的eyshlist
最新回复
(
0
)