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
For 150 years scientists have tried to determine the solar constant, the amount of solar constant energy that reaches the Earth.
For 150 years scientists have tried to determine the solar constant, the amount of solar constant energy that reaches the Earth.
admin
2017-06-30
77
问题
For 150 years scientists have tried to determine the solar constant, the amount of solar constant energy that reaches the Earth. Yet, even in the most cloud-free regions of the planet, the solar constant cannot be measured precisely. Gas molecules and dust particles in the atmosphere absorb and scatter sunlight and prevent some wavelengths of the light from ever reaching the ground.
With the advent of satellites, however, scientists have finally been able to measure the Sun’s output without being impeded by the Earth’s atmosphere. Solar Max, a satellite from the National Aeronautics and Space Administration(NASA), has been measuring the Sun’s output since February 1980. Although a malfunction in the satellite’s control system limited its observation for a few years, the satellite was repaired in orbit by astronauts from the space-shuttle in 1984. Max’s observations indicate that the solar constant is not really constant after all. The satellite’s instruments have detected frequent, small variations in the Sun’s energy output, generally amounting to no more than 0. 05 percent of the Sun’s mean energy output and lasting from a few days to a few weeks. Scientists believe these fluctuations coincide with the appearance and disappearance of large groups of sunspots on the Sun’s disk. Sunspots are relatively dark regions on the Sun’s surface that have strong magnetic fields and a temperature about 2, 000 degrees Fahrenheit cooler than the rest of the Sun’s surface. Particularly large fluctuations in the solar constant have coincided with sightings of large sunspot groups. In 1980, for example, Solar Max’s instruments registered 0. 3 percent drop in the solar energy reaching the Earth. At that time a sunspot group covered about 0. 6 percent of the solar disk, an area 20 times larger than the Earth’s surface.
Long-term variations in the solar constant are more difficult to determine. Although Solar Max’s data have indicated a slow and steady decline in the Sun’s output, some scientists have thought that the satellite’s aging detectors might have become less sensitive over the years, thus falsely indicating a drop in the solar constant. This possibility was dismissed, however, by comparing Solar Max’s observations with data from a similar instrument operating on NASA’s Nimbus 7 weather satellite since 1978.
Why did scientists think that Solar Max might be giving unreliable information?
选项
A、Solar Max did not work for the first few years.
B、Solar Max’s instruments were getting old.
C、The space shuttle could not fix Solar Max’s instruments.
D、Nimbus 7 interfered with Solar Max’s detectors.
答案
B
解析
细节题。答案在第二段thought the satellite’s(Solar Max)aging detectorsmight have less sensitive over the years.”科学家认为不可靠是因为他们认为这颗卫星的探测器老化了,测量不准,因此答案选B。
转载请注明原文地址:https://kaotiyun.com/show/vSFO777K
0
考博英语
相关试题推荐
Thegovernmentistryingtodosomethingto_____betterunderstandingbetweenthetwocountries.
Clonaid,acompanyassociatedbyagroupthatbelievesextraterrestrialscreatedmankind,announcedFridaythatithadproduced
Herremarks____acompletedisregardforhumanrights.
Asaresultofthestrike,theGovernmentisurgingpeopletobe______withelectricity.
AfricanAmericanwomen’ssearchforsocietalacceptanceoftenencompassesstrugglebetweennaturalandsociallyconstructedidea
Whenitcomestotheslowingeconomy,EllenSperoisn’tbitinghernailsjustyet.Butthe47-year-oldmanicuristisn’tcutting,
Inthe2006filmversionofTheDevilWearsPrada,MirandaPriestly,playedbyMerylStreep,scoldherunattractiveassistantfo
Supposeyougointoafruiterer’sshop,wantinganapple-youtakeupone,andonbitingityoufinditissour;youlookatit,
Supposeyougointoafruiterer’sshop,wantinganapple-youtakeupone,andonbitingityoufinditissour;youlookatit,
随机试题
浅Ⅱ度烧伤,若无感染等并发症,通常愈合时间为【】
A.不可逆性抑制B.竞争性抑制C.非竞争性抑制D.反竞争性抑制抑制剂与酶活性中心上的必需基团以共价键结合,属于
患者因左上侧切牙冠折,要求做烤瓷修复灌注印模的烤瓷修复工作模型材料应选用
足三阳经在下胰的分布规律是()
A、抗精神病作用B、镇吐作用C、体温调节失灵D、锥体外系反应E、催乳素分泌增加氯丙嗪抑制下丘脑体温调节中枢可以引起()
中国进行百团大战时,欧洲战场正在进行()。
莱文森考察稳定期与转折期的标准是
下列关于全国人民代表大会代表法律地位的表述,错误的是()。
[*]
•Lookatthenotesbelow.•Someinformationismissing.•Youwillhearanengineeringmanagergivingasecretarysomeinforma
最新回复
(
0
)