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
95
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://kaotiyun.com/show/JTvO777K
0
专业英语八级
相关试题推荐
WhyisCaliforniacalledtheGoldenState?
Wastingwoodisaseriousprobleminconservingtheresources,whicharedistributedunevenlyandaffectedbyothernaturalfact
WhydoconservationistsinAustraliasupportthepolicyofkillingcats?
The5thWorldInternetConferenceattractedabout1,500participantsfrom76countriesandregionsintheworld.
HowmuchofthePalaceMuseumremainedclosedtothepublicin2012?
DeclanMayes,PresidentoftheMusicBuyersAssociation,isfuriousatarecentannouncementbytherecordingindustryregarding
Intheinformationtechnologyindustry,itiswidelyacknowledgedthathowwellITdepartmentsofthefuturecanfulfilltheirb
Everyhumanbeingisfallible;wemakemistakes.InAmericawhenamistakehasbeenmade,itisconsideredfittingfortheperso
我们在线课程是对那些刚刚登记的学生公开的,它包括了学生学习中需要的所有东西。我们的学生既喜欢它的质量也喜欢它的便捷。这句话不是很难,里面的单词也比较简单,如果能把第一句话听懂,差不多就没什么问题了。enrollment:登记的学生,报名的学生。
随机试题
隐睾的病理形态中,以下哪项是错误的?
张某与李某为邻居。一日张某回家路过李某家,见李妻独自一人在家收拾衣服,遂起歹念,便破门而入,将其推倒在院内柴堆上欲行强奸,李妻大声呼救。刚好民警王某下班路过听到,王某表明身份后,喝令张某住手。张某掏出随身携带的匕首袭击王某,刺伤王某胸部,王某倒地。张某仍持
教师在一次活动中提出的通过活动计划或教案体现的目标是()
下列哪一个不是异烟肼的不良反应
下丘脑属于
(2011年单项选择第39题)在工商谈判的收局阶段,为促成成交,可以采用结果比较法。下列做法中,属于结果比较法的是()。
刑法第267条规定:“抢夺公私财物;数额较大的,处3年以下有期徒刑、拘役或者管制,并处或者单处罚金…”甲抢夺数额较大的财物构成犯罪,对甲适用上述规定处罚,可能正确的处罚是:
下列四条地形起伏曲线中,()曲线与下图中的Ⅰ-l剖面最为对应。
设{an},{bn},{cn}均为非负数列,且cn=∞,则().
Thecomprehensionpassagesonthiscoursearedesignedtohelpyouincreaseyourspeed.Ahigherreadingrate,withnolossofc
最新回复
(
0
)