首页
登录
职称英语
For 150 years scientists have tried to determine the solar constant, the amo
For 150 years scientists have tried to determine the solar constant, the amo
游客
2025-04-02
12
管理
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. [br] The attempt to describe the solar constant can best be described as______.
选项
A、an ongoing research effort
B、a question that can never be answered
C、an issue that has been resolved
D、historically interesting, but irrelevant to contemporary concerns
答案
A
解析
细节题。从文章的表述我们可以知道虽然并没有取得很大的突破,科学家们仍然在努力,并且这种研究是有意义的。因而排除A选项“仍在努力中”是正确答案。
转载请注明原文地址:https://tihaiku.com/zcyy/4023603.html
相关试题推荐
Scientistsnowtendtoagreethatthenoiselevelforpotentialhearingloss
Scientistsnowtendtoagreethatthenoiselevelforpotentialhearingloss
Scientistsnowtendtoagreethatthenoiselevelforpotentialhearingloss
Scientistsgenerallyholdthatlanguagehasbeensolonginusethatthelength
Awayfromtheirprofession,scientistsareinherentlynomorehonestorethicalt
____scientistshaveobservedincreasedpollutioninthewatersupply.A、LateB、La
Theworkintheofficewas______byaconstantstreamofvisitors.A、confusedB、ha
Thestormwas______andchangedcourseconstantlyatseaatthattime.A、chasteB、
【T1】Determinedtomakeitonhisown,Bushdidnottellhisfatherthathew
Scientistsnowtendtoagreethatthenoiselevelforpotentialhearingloss
随机试题
[originaltext]WelcometotheinformationlineoftheStateInvestmentSociety.
Themainpurposeofthepassageistoshow______.[br]Howhasthejobofthes
男性,52岁,重度肥胖,血压高,心、肾功能尚好,减体重的速度应控制在()
对胎儿进行防电磁保护,使他们能免受这些不良因素的伤害,顺利地来到人间,这是为了保
下列叙述中,正确的是()。A.CPU能直接读取硬盘上的数据 B.CPU能直
下列关于证券价格指数的说法错误的是()。A.常见的证券价格指数有股票价格指数和
D每一行中含有“B”字母的图形在下一行中旋转180°,注意第一行圆中有B,旋转180°后,位置变化看不出来。故答案为D。
产品组合中产品项目的总数是()。A:产品组合的宽度 B:产品组合的长度 C:
下列哪些项可用作接地极?()A.建筑物地下混凝土基础结构中的钢筋 B.埋地排
银行存款日记账是由出纳人员根据填制完毕的银行存款收、付款凭证,逐日逐笔根据经济业
最新回复
(
0
)