中间图

Or
阅读RC-15478 (第3/3题) Time Cost00:00
收藏
该题平均耗时:2m43s,平均正确率:51.2% 添加做题笔记

Before the age of space exploration, astronomers assumed that the Moon's core was smaller than the Earth’s, in both relative and absolute terms – the radius of the Earth's core is 55 percent of the overall radius of the Earth and the core's mass is 32 percent of the Earth's overall mass – but they had no way to verify this. Two sets of data gathered by Lunar Prospector have now given astronomers the ability to determine that the Moon's core accounts for 20 percent of the Moon's radius and for a mere 2 percent of its overall mass.

First, scientists measured minute, relatively rapid variations in the wavelength of radio signals from Lunar Prospector as the craft moved towards or away from the Earth. Using these variations, scientists accurately determined even slight changes in the craft's velocity while the craft orbited the Moon, changes resulting from inconsistency in the gravitational pull of the Moon on the craft. The data were used to create a "gravity map" of both near and far sides of the Moon, highlighting new details of the distribution of the Moon's internal mass. Scientists thus determined that the Moon has a small, metallic core, which, if composed mostly of iron, has a radius of approximately 350 kilometers. The second method involved examining the faint magnetic field generated within the Moon itself by the Moon's monthly passage through the tail of the Earth's magnetosphere. This approach confirmed the results obtained through examination of the gravity map.

The size and composition of the Moon's core have serious implications for our understanding of the Moon's origins. If the Moon and Earth developed as distinct entities, the sizes of their cores should be more comparable. In actuality, it seems that the Moon was once part of the Earth and broke away at an early stage in the Earth's evolution, perhaps due to a major asteroid impact that could have loosened a chunk of iron, allowing it to form the core around which the Moon eventually coalesced. Alternatively, according to fission theory, the early Earth may have spun so rapidly that it ejected a quantity of material by so-called centrifugal force, material that later coalesced by mutual gravitational attraction into the Moon.

According to the passage, the magnetic field within the Moon’s core

  • 分析A选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析B选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析C选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析D选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析E选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
暂无雷哥网文字解析
当前还没有完善解析,欢迎在这里提交你的解答,等待老师审核~

题目讨论 3条评论)

用户头像
提交
  • 用户头像
    680461elv

    注意提问的对象!confirm“gravity map”的是这个研究方法,而不是月球内部重力场。
    0 0 回复 2022-05-24 15:13:26
  • 用户头像
    230503fjuks

    inconsistencies in radio signal wavelength就是gravity map,但是confirm的是通过gravity map研究得到的结论而不是gravity map本身
    1 0 回复 2020-05-06 17:44:25
  • 用户头像
    730以上

    定位原文:The second method involved examining the faint magnetic field generated within the Moon itself by the Moon's monthly passage through the tail of the Earth's magnetosphere.也就是说月亮通过地球的磁层尾端的时候月球被磁化了有了磁场。
    0 0 回复 2018-06-17 21:18:24
    本题信息

    2m43s

    平均耗时

    51.2%

    平均正确率

    • 题目来源1:Manhattan

    该题由网友i2zZvD提供 上传GMAT题

    • 手机注册
    • 邮箱注册
    登录>







    关闭图标

    标题图

    • 图标

      知识库学习

      GMAT语法、逻辑、阅读、数学各单项备考知识点学习及测验
    • 图标

      在线做题

      包含GMAT各单项必考知识点题目、OG/PREP/GWD/雷哥讲义题目、难度650/680/700/730题库题目练习及题目解析
    • 图标

      在线模考

      语文套题/数学套题/全套仿真模考,包含GWD/PERP/精选模考等上百套套题模考
    • 图标

      在线测评

      适合5种不同基础的GMAT学员,测评后可自动出具分数报告及复习计划指导
    • 图标

      资料下载

      GMAT必备备考资料下载、鸡精下载、课程课件等免费下载
    • 图标

      课程学习

      注册会员后,可在GMAT课程区,选择免费直播课程及公开课程进行在线学习
    ×
    请你选择你要查看的模考成绩单
    立即开通 暂不开通
    加载图片
    网络异常