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
Mercury, the planet nearest the sun, is difficult to observe from the Earth because it rises and sets within two hours of the su
Mercury, the planet nearest the sun, is difficult to observe from the Earth because it rises and sets within two hours of the su
admin
2015-01-30
53
问题
Mercury, the planet nearest the sun, is difficult to observe from the Earth because it rises and sets within two hours of the sun. Consequently, little was known about the planet until the Mariner 10 spacecraft made several flybys in 1974 and 1975.
Planetary scientists can estimate the age of a planet’s surface by the number of impact craters on it. In general, the older the surface, the more crates it has. Some regions on Mercury are heavily cratered, suggesting that they are very old surfaces that were probably formed about 4 billion years ago. Between these regions are areas of gently rolling plains that may have been smoothed by volcanic lava flows or by accumulated deposits of fine material ejected during impacts. These plains are also old enough to have accumulated a large number of impact craters. Elsewhere on the planet are smooth, flat plains that are probably younger and volcanic in origin. These plains have relatively few impact craters. Sometime between the formation of the intercrater plains and the formation of the smooth plains, the whole planet may have shrunk as it cooled, causing the crust to buckle and form the long, steep cliffs called scarps.
The largest impact basin on Mercury has a diameter of about 800 miles and is surrounded by mountains that rise to heights of about 1.2 miles. The crater was probably created by the impact of a large planetesimal when Mercury was forming. On the opposite side of the planet is an area of hilly, linear terrain that probably resulted from seismic waves caused by the same impact.
Like other airless, solid bodies in the solar system, the entire surface of Mercury is covered with a layer of rubble called regolith, which is composed of material, ranging from dust to boulders, that was scattered when impact craters were formed. This debris was in turn broken up and redistributed by subsequent impacts.
Mercury is very dense and has a magnetic field that is about 1 percent as strong as the Earth’s. This suggests the existence of a planetary core composed of iron and nickel and constituting about 40 percent of the planet’s volume. The surface gravity is about one-third as strong as the Earth’s, and a thin atmosphere surrounds the planet. Radar images taken of Mercury in 1991 show what are considered to be large ice patches at the planet’s north pole.
Directions: Complete the following sentences with information given in the passage in a maximum of 10 words for each blank.
The layer of rubble covering Mercury is called______.
选项
答案
regolith
解析
转载请注明原文地址:https://kaotiyun.com/show/FaVK777K
本试题收录于:
C类竞赛(非英语专业本科)题库大学生英语竞赛(NECCS)分类
0
C类竞赛(非英语专业本科)
大学生英语竞赛(NECCS)
相关试题推荐
Whichofthefollowingitalicizedpartsisusedasanobjectcomplement(宾语补足语)?
Youwillseetoitthateverythingisreadybeforetheguestsarrive.Theunderlinedpartmeans________.
A、Hewasafraidthewomanfelldownthemountain.B、Hewasafraidthewomanwasangrywithhim.C、Hewasafraidthewomantookh
(1)Menandwomentendtochoosedifferentcareerpaths,andresearchershaveidentifiedthisasthebiggestreasonmenmakemor
Itwasduringsummerbreaksthatwefirsttastethesatisfactionof________workintomoney.
believeapparentwillingmakethreeItisafairlycommon【16】______inBritainthatmenthesedaysdomorehous
Certainbirdsare,moreoftenthannot,consideredbadluck,orevenfrightening,asignofimpendingdeath.Allovertheworld,
Thesubjectofthislectureishorology,thescienceofmeasuringtime.The【D1】______hascomealongwaysinceancienttimes.It
Thesubjectofthislectureishorology,thescienceofmeasuringtime.The【D1】______hascomealongwaysinceancienttimes.It
【B1】______Manyofthesecustomsincludestoriesandbeliefsrelatedtocreatures,realormagical,takingtheteeth.InAsia,fo
随机试题
自然派
可用阴阳互根互用关系说明的有
下列哪种疾病触诊语颤消失
乙型脑炎病毒下列哪项描述不正确
按照《建设项目环境保护管理条例》的规定,建设单位应当在( )报批环评文件。
某商品原报单价为:CIFC2%NewYorkUSD3000/MT,外商要求将佣金率提高至5%,在保持我方净收入不变的情况下,应如何报价?(保留两位小数)
我国政府明令禁止进口的货物包括:列入由国务院对外贸易主管部门或由其会同国务院有关部门制定的《禁止进口货物目录》的商品和国家有关法律、法规明令禁止进口的商品以及其他各种原因停止进口的商品。请指出以下哪些属于国家禁止进口的货物:
公民、法人和其他组织对()不服,不能申请劳动保障行政复议。
体内有性质明确、部位具体的异常知觉,属于()。
Justlikechildren,deeroftencrossBritishroadstogettotheotherside.Butthecostisthedeer’slife.Atnight,【S1】____
最新回复
(
0
)