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
The spectacular aurora light displays that appear in Earth’s atmosphere around the north and south magnetic poles were once myst
The spectacular aurora light displays that appear in Earth’s atmosphere around the north and south magnetic poles were once myst
admin
2019-08-27
92
问题
The spectacular aurora light displays that appear in Earth’s atmosphere around the north and south magnetic poles were once mysterious phenomena. Now, scientists have data from satellites and ground-based observations from which we know that the aurora brilliance is an immense electrical discharge similar to that occurring in a neon sign.
To understand the cause of auroras, first picture the Earth enclosed by its magnetosphere, a huge region created by the Earth’s magnetic field. Outside the magnetosphere, blasting toward the earth is the solar wind, a swiftly moving plasma of ionized gases with its own magnetic filed. Charged particles in this solar wind speed earthward along the solar wind’s magnetic lines of force with a spiraling motion. The Earth’s magnetosphere is a barrier to the solar winds, and forces the charged particles of the solar wind to flow around the magnetosphere itself. But in the polar regions, the magnetic lines of force of the Earth and of the solar wind bunch together. Here many of the solar wind’s charged particles break through the magnetosphere and enter Earth’s magnetic field. They then spiral back and forth between the Earth’s magnetic poles very rapidly. In the polar regions, electrons from the solar wind ionize and excite the atoms and molecules of the upper atmosphere, causing them to emit aurora radiations of visible light.
The colours of an aurora depend on the atoms emitting them. The dominant greenish white light comes from low energy excitation of oxygen atoms. During huge magnetic storms oxygen atoms also undergo high energy excitation and emit crimson light. Excited nitrogen atoms contribute bands of colour varying from blue to violet. Viewed from outer space, auroras can be seen as dimly glowing belts wrapped around each of the Earth’s magnetic poles. Each aurora hangs like a curtain of light stretching over the polar regions and into the higher latitudes. When the solar flares that result in magnetic storms and aurora activity are very intense, aurora displays may extend as far as the southern regions of the United States.
Studies of auroras have given physicists new information about the behavior of plasmas, which has helped to explain the nature of outer space and is being applied in attempts to harness energy from the fusion of atoms.
The passage supports which of the following statements about scientists’ understanding of auroras?
选项
A、Before advances in technology, including satellites, scientists knew little about auroras.
B、New knowledge about the fusion of atoms allowed scientists to learn more about auroras.
C、Scientists cannot explain the cause of the different colours in auroras.
D、Until scientists learn more about plasma physics, little knowledge about auroras will be available.
答案
A
解析
本题细节定位于第一段第一和第二句话“The spectacular aurora light displays that appear in Earth’s atmosphere…were once mysterious phenomena.Now, scientists have data from satellites and ground-based observations…in a neon sign”。由此可知,在地球南北磁极周围的大气层中出现的极光曾经是神秘的现象。如今,科学家们己经从卫星和地面观测得到的数据了解了这种现象。据此可知,在包括卫星在内的科技进步之前,科学家对极光现象所知甚少,因此选择A。
转载请注明原文地址:https://kaotiyun.com/show/gbTO777K
0
考博英语
相关试题推荐
Hiddenhotelcostscanbeasourceoffrustrationtothefrugaltraveler.
Duringrecentyearswehaveheardmuchabout"race":howthisracedoescertainthingsandthatracebelievescertainthingsand
Forme,scientificknowledgeisdividedintomathematicalsciences,naturalsciencesorsciencesdealingwiththenaturalworld(
Tocallsomeonebird-brainedinEnglishmeansyouthinkthatpersonissillyorstupid.Butwillthisdescriptionsoondisappear
Tocallsomeonebird-brainedinEnglishmeansyouthinkthatpersonissillyorstupid.Butwillthisdescriptionsoondisappear
Sincetheearlynineties,thetrendinmostbusinesshadbeentowardon-demand,always-availableproductsandservicesthatsuit
Ateacherissomeonewhocommunicatesinformationorskillsothatsomeoneelsemaylearn.Parentsarethe【C1】______teachers.Ju
Althoughwomenclustertohimlikemothsaroundaflame,heisnone______happierforit.
IndustrialproductionmanagerscoordinatetheresourcesandactivitiesrequiredtoproducemillionsofgoodseveryyearintheU
Oneofthemostdifficultaspectsofdecidingwhethercurrentclimaticeventsrevealevidenceoftheimpactofhumanactivities
随机试题
国有土地使用权终止的情形有()。
一马耳下局部出现疼痛、肿胀及增温,触之敏感。病马流涎、食欲减退、吞咽困难。根据上述症状,该病最可能是
心胸烦热,口渴面赤,口舌生疮者,治疗应选用
某政府投资项目,主要分为建筑工程、安装工程和装修工程3部分,项目投资为5000万元,其中,估价为80万元的设备由招标人采购。招标文件中,招标人对投标有关时限的规定如下:(1)投标截止时间为自招标文件停止出售之日起第15日上午9时整;
【背景资料】某机电安装公司承包了一造纸车间的机电安装工程,包括属于本车间的槽罐制作安装任务(含有两台碳钢压力容器)。合同规定,除工艺设备外的所有材料均由施工单位采购,拖延工期要重罚,对于文明施工也提出了具体要求。由于工期特别紧张,业主要求土建基础
背景材料:桌市政工程项目施工合同价为560万元,合同工期为6个月。施工合同规定如下:(1)开工前业主向施工单位支付合同价20%的预付款。(2)业主自第一个月起,从施工单位的应得工程款中按10%的比例扣留保留金,保留金限额暂定为合同价的5%,保留金到第
关于绩效贡献分析,下列说法正确的是()。
ABC公司下设A、B两个投资中心,没有持有金融资产,A投资中心的平均经营资产为700万元,平均经营负债为350万元,部门投资报酬率为20%;B投资中心的部门投资报酬率为22%,剩余收益为105万元,平均经营负债为320万元;ABC公司对A中心要求的平均最低
建立在清楚的逻辑基础上,并使它的决策方法和决策过程有固定的规律可循,可事先规定明确规则的决策足()。
将E―R图转换为关系模式时,实体和联系都可以表示为()。
最新回复
(
0
)