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
Lunar sight-seeing trips and orbiting space hotels are within reach, moon walking astronaut Edwin"Buzz" Aldrin said last week, b
Lunar sight-seeing trips and orbiting space hotels are within reach, moon walking astronaut Edwin"Buzz" Aldrin said last week, b
admin
2010-01-18
41
问题
Lunar sight-seeing trips and orbiting space hotels are within reach, moon walking astronaut Edwin"Buzz" Aldrin said last week, but some who favor space tourism worried about its "giggle factor". Astronomers have known for years that a source of intense energy emissions lies at the center of the Milky Way Galaxy, obscured from view by vast clouds of dust and gas. In February, 1992, researchers at the Max Planck Institute in Garching, Germany, reported evidence that the mysterious energy source is a gigantic black hole.
Observations have shown that many strong energy sources lie at the heart of the Milky Way. One of them, called Sagittarius A, is thought to be the actual center of the Galaxy, the point about which the great spiral of stars rotates. Sagittarius A is a powerful emitter of radio waves and X-rays.
Astronomers have considered two possible explanations for the identity of Sagittarius A. They theorized that it is either a compact duster of normal stars or a super-massive black hole containing as much as a million or more suns. The German scientists reported that they found strong evidence in support of the black hole explanation.
The astronomers used a new telescope high in the Andes Mountains of Chile to obtain the sharpest images ever made of the region around Sagittarius A. The image shows that Sagittarius A is a single, small object rather than a duster of stars.
The researchers also found that a bubble of gas is expanding outward from Sagittarius A. This expanding gas is similar in temperate, density, and composition to the jets of gas that astronomers have observed flow hag away from the centers of many other galaxies. Such jets are thought to be generated by accretion disks surrounding enormous black holes. Accretion disks are vast, swirling masses of gas and dust that give off titanic amounts of energy as they are sucked into the black hole. The similarity between the jets emitted by some galaxies and the gas bubble surrounding Sagittarius A supports the idea that Sagittarius A is a super-massive black hole.
Sagittarius A is ______.
选项
A、clearly a super-massive black hole
B、a compact cluster of normal stars
C、a single, small subject
D、still an issue of controversy
答案
D
解析
文章第三段指出,天文学家对于Sagittarius A的身份提出了两种可能的解释,而综观全文可知,尽管他们发现了一些用来证明Sagittarius A是黑洞的证据,但这毕竟在整个科学界尚未形成定论,因此[D]为正确答案。
转载请注明原文地址:https://jikaoti.com/ti/nx9YFFFM
0
专业英语八级
相关试题推荐
Peopleofdifferentfieldscametogetherforthesamedreamofbuildingasmartcity.
WhydoconservationistsinAustraliasupportthepolicyofkillingcats?
Whatcanwelearnabouttheonlineschoolaccordingtothepassage?
Whathavescientistsconcludedthroughstudiesovertheyears?
Everyhumanbeingisfallible;wemakemistakes.InAmericawhenamistakehasbeenmade,itisconsideredfittingfortheperso
Whenprehistoricmanarrivedinnewpartsoftheworld,somethingstrangehappenedtothelargeanimals:theysuddenlybecameex
A、Peopleeverywherehavebadheadachesduringtimeofforcefulwinds.B、Theweatherconditionsoftheatmospheregreatlyinfluen
Mostearthquakesoccurwithintheupper15milesoftheearth’ssurface.Butearthquakescananddooccuratalldepthstoabout
Listeningisoneofthefirstthingswelearntodoandoneofthethingswedomost.Theaveragepersonspends【C1】______ofthei
Listeningisoneofthefirstthingswelearntodoandoneofthethingswedomost.Theaveragepersonspends【C1】______ofthei
随机试题
狼疮性肾炎一般不表现为
房地产经纪机构购买业务保险,属于风险管理的()方法。
在监理招标的评标办法中,一般采取(),且报价所占比例较低。
施工总进度计划由()组织进行编制。
甲公司是一家制造类企业,全年平均开工250天。为生产产品,全年需要购买A材料250000件,该材料进货价格为150元/件,每次订货需支付运费、订单处理费等变动费用500元,材料年储存费率为10元/件。A材料平均交货时间为4天。该公司A材料满足经济订货基本
10+20+30+……+970+980+990+1000+990+980+970+……+30+20+10=()。
运输公司信息管理系统吐哈油田运输公司信息管理系统是天启软件股份有限公司历时一年潜心研制的企业级信息应用软件,本着高标准、高起点的理念,造就了高品质的吐哈运输公司管理信息系统。根据用户的实际要求,天启软件有限公司独创动态报表引擎设计,内置天启软件公司自主
一个人出现过分地、不合理地害怕外界客体或处境的现象,就有可能具有()的症状。
社会治安综合治理,是公安工作中党的领导、公安机关和政府部门三者有机结合的新形式,是公安工作党委领导的根本原则和群众路线在新形势下的新发展。()
设变量已正确定义并赋值,以下正确的表达式是
最新回复
(
0
)