首页
登录
职称英语
Astronomy: The Auroras[img]2012q1/ct_etoefm_etoeflistz_0535_20121[/img] [br] Wha
Astronomy: The Auroras[img]2012q1/ct_etoefm_etoeflistz_0535_20121[/img] [br] Wha
游客
2025-02-08
3
管理
问题
Astronomy: The Auroras
[br] What colors are commonly seen in the auroras? Click on two answers.
W: For centuries, people have told stories to explain the moving lights in the night sky—the curtains of greenish-white light with pink fringe. People described these lights as the breath of the Earth, powerful spirits, or angel light. An early twentiethcentury explorer wrote about the "bloody red" and "ghostly green" lights. These lights, of course, are the aurora borealis—the northern lights—and, in the south, the aurora australis. Most of the time they’re greenish-yellow, but sometimes they take colors from violet to red. The auroras can be seen at any time of the year, with the right atmospheric conditions. They’re most often seen near the North and South Poles, during times of maximum solar activity. The closer to the North or South Pole you are, the better you can see the lights.
The auroras occur in the ionosphere. The ionosphere is the layer of the upper atmosphere where high energy solar radiation strips electrons from oxygen and nitrogen atoms, and leaves them as positively charged ions. The auroras are the result of a complex interaction between the solar wind and the Earth’s magnetic field. Here’s what happens. The sun’s heat charges the particles in the solar wind, a stream of electrically charged subatomic particles that continually emanates from the sun. As the solar wind approaches Earth, it’s deflected by Earth’s magnetic field and diverted north and south toward the magnetic poles. The interaction between the solar wind and the magnetosphere generates beams of electrons. These electrons collide with atoms and molecules within the ionosphere near Earth’s magnetic poles. The collisions rip apart molecules and excite atoms. Thus, oxygen and nitrogen atoms in the ionosphere become "excited, "or ionized. The auroras happen when these ionized atoms return to their normal state from their excited, energized states. The ions combine with free electrons—as they do so, they emit radiation. Part of this radiation is visible light: the aurora borealis and aurora australis.
Yes, Simon?
M: Uh ... it sounds kind of like electricity.
W: Yes, that’s right. The auroras are an electrical phenomenon. As you know, an electrical generator has two components: a conductor and a magnetic field. To generate electricity, the conductor has to move across the field to produce a force. With the auroras, the conductor is the solar wind carrying a stream of charged particles.
M: So, what happens is, when, uh, when the charged particles reach Earth’s magnetic field, they, uh, move along in the field towards the north and south magnetic poles.
W: Exactly. And then the particles collide with gases in the atmosphere—oxygen and nitrogen—and the oxygen and nitrogen atoms get excited. And then, when the particles get de-excited and return to their normal state, they emit the auroras by releasing energy in the form of light. Oxygen releases either dark red or ghostly green. Nitrogen emits rosy pink or magenta. The activity of the auroras varies with the sun’s activity. When the sun is quiet, the auroras can be seen only in a small area. When the sun is active, however, the aurora borealis can be seen across southern Canada and the northern United States.
选项
A、Orange
B、Red
C、Green
D、Brown
答案
BC
解析
Red and green are commonly seen in the auroras. The professor says An early twentieth- century explorer wrote about the "bloody red" and "ghostly green" lights; Most of the time they’re greenish-yellow, but sometimes they take colors from violet to red. (2.2)
转载请注明原文地址:https://tihaiku.com/zcyy/3948320.html
相关试题推荐
Conversation:CampusNewspaper[img]2012q1/ct_etoefm_etoeflistz_0529_20121[/img]
Conversation:CampusNewspaper[img]2012q1/ct_etoefm_etoeflistz_0529_20121[/img]
Conversation:CampusNewspaper[img]2012q1/ct_etoefm_etoeflistz_0529_20121[/img]
[img]2012q1/ct_etoefm_etoefwritea_1919_20121[/img]Integrate
[img]2012q1/ct_etoefm_etoefspeakc_1404_20121[/img]Nowlistentopartofal
[img]2012q1/ct_etoefm_etoefspeakc_1403_20121[/img]Nowlistentoashortcon
"HistoryClass"[img]2012q1/ct_etoefm_etoeflistz_1619_20121[/img][br]Whydoest
"HistoryClass"[img]2012q1/ct_etoefm_etoeflistz_1619_20121[/img][br]Whatdoes
"HistoryClass"[img]2012q1/ct_etoefm_etoeflistz_1619_20121[/img][br]Whatisth
"BiologyClass"[img]2012q1/ct_etoefm_etoeflistz_1612_20121[/img][br]Whydoest
随机试题
Thestatementcompletelylaidbareits______forworldconquest.A、admirationB、
Haveyoueverreceived______ofwhathashappenedtoher?A、thewordB、wordsC、w
A.轻度皮肤黏膜出血伴骨髓增生减低,雄激素治疗有效 B.血小板数量减少伴巨核细
护士在准备注射用物时发现治疗盘内有一些碘渍,应选用何种溶液除去碘渍A.戊二醛溶液
下列事项须由股东大会以特别决议通过的是()。A.董事会和监事会成员的报酬和支
根据信托财产运用方式的不同,信托业务可以分为()。A.资金信托 B.财产信托
燥邪致病多从A.以上都不是 B.经络而入 C.腠理而入 D.皮毛而入 E
左边给定的是纸盒外表面的展开图,右边哪一项能由它折叠而成?请把它找出来: A.
商业、旅游、娱乐等经营性用地可用招标出让国有土地使用权方式来获取土地使用权。
下列施工合同中,属于可撤销合同的有( )。A.施工合同订立时,工程款支付条款显
最新回复
(
0
)